Flexible Structure Research Articles

Sliding and rocking response of a flexible structure on a rigid block using floating frame of reference formulation

Sliding and rocking response of a flexible structure on a rigid block using floating frame of reference formulation

Challenges, Benefits, and Motivations in Paraphrasing: Insights from Marine and Fisheries EFL Students

This study explores the challenges, motivations, and benefits of paraphrasing for Marine and Fisheries EFL students, aiming to uncover factors that impact their ability to rephrase academic texts. Using a descriptive qualitative approach, data were collected through field notes and semi-structured interviews with 15 purposively sampled students. The findings reveal that students face significant challenges in paraphrasing due to limited vocabulary, difficulties in sentence restructuring, and low self-confidence. Some students perceive English proficiency as less relevant to their future careers, reducing motivation to enhance their language skills. However, regular paraphrasing practice was found to provide valuable benefits, including vocabulary expansion, improved understanding of sentence structures, and increased confidence in handling technical content. These outcomes underscore the potential of paraphrasing exercises to support academic skill-building and professional readiness in specialized fields. The study suggests the need for targeted pedagogical strategies that emphasize vocabulary development, structural flexibility, and confidence-building. These findings contribute to the understanding of paraphrasing in EFL contexts and offer practical recommendations for enhancing students’ language skills in discipline-specific academic environments.

Challenges and Strategies for the Sustainable Architectural Education in the Context of Post-Urbanization and Climate Change

The transformation of urbanization patterns due to the pandemic and climate change have significantly reshaped construction market demands, presenting substantial challenges to current architectural education (AE) models. In order to address these challenges and propose effective reform strategies, this study utilizes questionnaires and expert interviews to gather perspectives from architecture students and professionals in a Chinese university. The findings highlight three main issues in AE: (1) misalignment between talent development stages and educational goals; (2) slow updates to curriculum content, leading to lagging behind the needs of times; and (3) inadequate integration of curriculum design with practical application, coupled with excessively lengthy academic programs. To address these challenges, the study proposes the strategies: (1) adopting multi-objective and multi-track approaches for educational goals; (2) reducing length of programs and implementing flexible academic structures; and (3) developing curricula that integrate knowledge with practice. This research offers valuable insights for reforming architectural education within the framework of sustainable development, emphasizing the need for educational goals, curriculum, and cultivation system to evolve to meet the demands of modern practice and development.

Molecular mechanism underlying effect of D93 and D289 protonation states on inhibitor-BACE1 binding: exploration from multiple independent Gaussian accelerated molecular dynamics and deep learning

ABSTRACT BACE1 has been regarded as an essential drug design target for treating Alzheimer’s disease (AD). Multiple independent Gaussian accelerated molecular dynamics simulations (GaMD), deep learning (DL), and molecular mechanics general Born surface area (MM-GBSA) method are integrated to elucidate the molecular mechanism underlying the effect of D93 and D289 protonation on binding of inhibitors OV6 and 4B2 to BACE1. The GaMD trajectory-based DL successfully identifies significant function domains. Dynamic analysis shows that the protonation of D93 and D289 strongly affects the structural flexibility and dynamic behaviour of BACE1. Free energy landscapes indicate that inhibitor-bound BACE1s have more conformational states in the protonated states than the wild-type (WT) BACE1, and show more binding poses of inhibitors. Binding affinities calculated using the MM-GBSA method indicate that the protonation of D93 and D289 highly disturbs the binding ability of inhibitors to BACE1. In addition, the protonation of two residues significantly affects the hydrogen bonding interactions (HBIs) of OV6 and 4B2 with BACE1, altering their binding activity to BACE1. The binding hot spots of BACE1 recognized by residue-based free energy estimations provide rational targeting sites for drug design towards BACE1. This study is anticipated to provide theoretical aids for drug development towards treatment of AD.

Dynamic response of rock landslides and avalanche debris flows impacting flexible barriers based on shaking table tests

Flexible barrier structures are commonly installed in mountainous regions to resist the impact effects of rock avalanches. Without reliable physical data, the study of rock landslide initiation and the impact mechanism of avalanche debris flow under seismic excitation remains poorly understood. In this study, a model of rock slope-flexible barrier system was developed to simulate seismic slope failure behavior and debris flow impact on flexible barriers. Seismic waves in shaking table tests were triaxially loaded to effectively simulate actual seismic responses. The results indicate that the response of the Acceleration Amplification Factor (AAF) is closely associated with seismic damage and deformation within the overlying rock layers and differential propagation of seismic energy on either side of the shear band triggers rockslide initiation. Furthermore, the progressive failure mode of modeled slopes under multiple seismic events is slip-compression cracking failure. Crushing spreading at the intersection of the cracking and slip surfaces is the source of the loose fractured rock mass. Finally, this paper examines the impact patterns and dynamic responses of large individual blocks and loose fractured deposits on flexible barriers. Large blocks cause localized strong acceleration in the steel wire nets, increasing the risk of local damage, whereas loose deposits tend to induce overall seismic deformation and instability of the supporting structure. The natural seismic damage mechanisms of the barrier structure are revealed. It is recommended that flexible barrier structures in earthquake-prone mountainous areas incorporate a reasonable footing design to ensure the columns can deflect out-of-plane in response to seismic activity.

A data density-based measure of dexterity for continuum robots and its comparative study

Abstract Continuum robot-based surgical systems are becoming an effective tool for minimally invasive surgery. A flexible, dexterous, and compact robot structure is suitable for carrying out complex surgical operations. In this paper, we propose performance metrics for dexterity based on data density. Data density at a point in the workspace is higher if the number of reachable points is higher, with a unique configuration lying in a small square box around a point. The computation of these metrics is performed with forward kinematics using the Monte Carlo method and, hence, is computationally efficient. The data density at a particular point is a measure of dexterity at that point. In contrast, the dexterity distribution property index is a measure of how well dexterity is distributed across the workspace according to desired criteria. We compare the dexterity distribution property index across the workspace with the dexterity index based on the dexterous solid angle and manipulability-based approach. A comparative study reveals that the proposed method is simple and straightforward because it uses only the position of the reachable point as the input parameter. The method can quantify and compare the performance of different geometric designs of hyper-redundant and multisegment continuum robots based on dexterity.

TRANSFORMASI DIGITAL DAN PENGARUHNYA TERHADAP BUDAYA ORGANISASI: TINJAUAN LITERATUR SISTEMATIS

Digital transformation has become a global phenomenon reshaping how organizations in Indonesia operate and compete. This study aims to analyze the impact of digital transformation on organizational culture through a systematic literature review (SLR), focusing on aspects of collaboration, structural flexibility, resistance to change, and value adaptation. The results indicate that digital transformation enhances collaboration and flexibility within organizations, fostering better cross-departmental communication and responsiveness to market changes. However, resistance to change emerges as a significant challenge, particularly among employees concerned about their roles. Adapting organizational values towards a more open and innovative culture also requires continuous support from leadership. In conclusion, the success of digital transformation depends on a holistic and comprehensive change management approach. This study provides guidance for organizations to design cultural strategies that support the sustainability of digital transformation in Indonesia.

Deep Eutectic Solvents for Next-generation Cyclodextrin Science

Abstract In cyclodextrin science, water has been almost exclusively employed as solvent, and this imposes non-negligible limitations to the scope of applications. Accordingly, deep eutectic solvents, constructed from hydrogen-bonding donors and acceptors, have been attracting much interest as important substitutes of water. This review comprehensively covers chemical and physicochemical features of cyclodextrins in these eco-friendly solvents. In one category, cyclodextrins or their derivatives are dissolved as solutes in conventional deep eutectic solvents. All of α-, β-, and γ-cyclodextrins efficiently form inclusion complexes with various guest molecules, exactly as observed in water. Notably, chemically modified cyclodextrins (e.g., 2-hydroxypropyl-cyclodextrins) form still more stable inclusion complexes than native cyclodextrins. Alternatively, deep eutectic solvents are prepared by combining cyclodextrins with other hydrogen-bonding components. The cyclodextrin units in these mixtures also form inclusion complexes with guest molecules. It has been proposed that enhanced flexibility of cylindrical structures of cyclodextrins allows effective induced-fit to stabilize inclusion complexes. The applications of these systems widely range from catalysis for organic synthesis to extraction, analysis, pharmaceutics, and many other fields. High solubilities of CDs and various chemicals in these solvents guarantee high productivity of target transformation, and unprecedentedly novel functions are promising for these unique systems.

Enhancing CO2/N2 and CO2/CH4 Separation Properties of PES/SAPO-34 Membranes Using Choline Chloride-Based Deep Eutectic Solvents as Additives

CO2 separation is an important environmental method mainly used in reducing CO2 emissions to mitigate anthropogenic climate change. The use of mixed-matrix membranes (MMMs) arrives as a possible answer, combining the high selectivity of inorganic membranes with high permeability of organic membranes. However, the combination of these materials is challenging due to their opposing nature, leading to poor interactions between polymeric matrix and inorganic fillers. Many additives have been tested to reduce interfacial voids, some of which showed potential in dealing with compatibility problems, but most of them lack further studies and optimization. Deep eutectic solvents (DESs) have emerged as IL substitutes since they are cheaper and environmentally friendly. Choline chloride-based deep eutectic solvents were studied as additives in polyethersulfone (PES)/SAPO-34 membranes to improve CO2 permeability and CO2/N2 and CO2/CH4 selectivity. SAPO-34 crystals of 150 nm with a high surface area and microporosity were synthesized using dry-gel methodology. The PES/SAPO-34 membranes were optimized following previous work and used in a defined composition, using 5 or 10 w/w% of DES during membrane preparation. All MMMs were characterized by their ideal gas permeability using N2 and CO2 pure gasses. Selected membranes were also tested using CH4 pure gas. The results presented that 5 w/w%, in polymer mass, of ChCl–glycerol presented the best result over the synthesized membranes. An increase of 200% in CO2 permeability maintains the CO2/N2 selectivity for the non-modified PES/SAPO-34 membrane. A CO2/CH4 selectivity of 89.7 was obtained in PES/SAPO-34/ChCl-glycerol membranes containing 5 w/w% of this DES, which is an outstanding ideal separation performance for MMMs when compared to other results in the literature. FTIR analysis reiterates the presence of glycerol in the membranes prepared. Dynamic Mechanical Thermal Analysis (DMTA) shows that the addition of 5 w/w% of DES does not impact the membrane flexibility or polymer structure. However, in concentrations higher than 10 w/w%, the inclusion of DES could lead to high membrane rigidification without impacting the overall thermal resistance. SEM analysis of DES-enhanced membranes presented asymmetric final membranes and reaffirmed the results obtained in DMTA about rigidified structures and lower zeolite–polymer interaction with higher concentrations of DES.

Performance Prediction of High-Entropy Perovskites La0.8Sr0.2MnxCoyFezO3 with Automated High-Throughput Characterization of Combinatorial Libraries and Machine Learning.

Perovskite oxides form a large family of materials with applications across various fields, owing to their structural and chemical flexibility. Efficient exploration of this extensive compositional space is now achievable through automated high-throughput experimentation combined with machine learning. In this study, we investigate the composition-structure-performance relationships of high-entropy La0.8Sr0.2MnxCoyFezO3±𝞭 perovskite oxides (0 < x, y, z <1; x+y+z≈1) for application as oxygen electrodes in Solid Oxide Cells. Following the deposition of a continuous compositional map using thin-film combinatorial pulsed laser deposition, compositional, structural, and performance properties are characterized using six different techniques with mapping capabilities. Random forests effectively model electrochemical performance, consistently identifying Fe-rich oxides as optimal compounds with the lowest area-specific resistance values for oxygen electrodes at 700 °C. Additionally, the models identify a statistical correlation between oxygen sublattice distortion-derived from spectral analysis of Raman-active modes-and enhanced performance.

Organizational Rigidity and Demands: A Qualitative Study on Nursing Work in Complex Organizations

Background/Objectives: The nursing work environment is a critical element in healthcare delivery and a strong predictor of both patient and nurse outcomes. Understanding the complexity and multifaceted nature of this environment is essential for improving nursing practices and optimizing healthcare systems. This study aimed to gain insights into the perceived characteristics of the nursing work environment, considering it as a complex and multifaceted system. Methods: A qualitative research approach was employed, involving 42 semi-structured interviews with 43 nurses and managers from academic, teaching, and general hospitals in The Netherlands. Data were collected between July 2020 and August 2021 through convenience sampling. Thematic coding was conducted to identify key patterns and themes. Results: The findings revealed that nurses demonstrated flexibility and a strong commitment to high-quality care, despite grappling with rigorous organizational tasks and processes. Four key themes emerged: (1) direct patient care as a standard feature of nursing work; (2) nurses’ flexibility for hospital productivity; (3) interdependencies, which decrease autonomous nursing practices; and (4) organizational structures that determine how nurses can shape their work. Nurses found it difficult to balance direct care with broader tasks due to organizational rigidity, revealing a gap between ideal nursing practices and daily reality. Conclusions: This study highlighted the challenges within the nursing work environment, particularly in balancing direct care with organizational demands. Addressing this gap between ideal nursing practice and reality requires a systems approach. This includes autonomous practices, supportive management, and flexible structures, allowing nurses to shape their work and enhance job satisfaction and care quality.

Molecular Evolution and Adaptation Strategies in Marine Ciliates: An Inspiration for Cold-Adapted Enzyme Engineering and Drug Binding Analysis

In the present review, we summarize genome mining of genomic data obtained from the psychrophilic Antarctic marine ciliate Euplotes focardii and its evolutionary-close mesophilic cosmopolitan counterpart E. crassus. This analysis highlights adaptation strategies that are unique to the Antarctic ciliate, including antioxidant gene duplication and distinctive substitutions that may play roles in increased drug binding affinity and enzyme reaction rate in cold environments. Enzymes from psychrophiles are usually characterized by high activities and reaction rates at low temperatures compared with their counterparts from mesophiles and thermophiles. As a rule, catalyst cold activity derives from an increased structural flexibility that may lead to protein denaturation in response to temperature fluctuation. Molecular thermolability has been a major drawback of using macromolecules from psychrophiles in industrial applications. Here, we report a case study in which the role of peculiar amino acid substitution in cold adaptation is demonstrated by site-directed mutagenesis. Combined with a rational design approach, these substitutions can be used for site-directed mutagenesis to obtain cold-active catalysts that are structurally stable. Furthermore, molecular docking analysis of β-tubulin isotypes extrapolated from E. focardii and E. crassus genomes allowed us to obtain additional insight on the taxol binding site and drug affinity. E. focardii genome mining and the comparison with the mesophilic sibling counterpart can be used as an inspiration for molecular engineering for medical and industrial applications.

Organic-Inorganic Hybrid Perovskite for Ferroelectric Catalysis.

Organic-inorganic hybrid perovskite ferroelectric has gained significant attention for its structural flexibility and diversity. They can directly utilize metal nodes and organic groups as active sites in catalysis. Additionally, their ferroelectric polarization occurs around these active sites, significantly enhancing catalytic activity and demonstrating immense potential for applications. However, their catalytic applications remain underexplored. This work marks the first utilization of the molecular perovskite ferroelectric [3,3-difluorocyclobutylammonium]2CuCl4 (Cu-DFCBA) as a catalyst for alkane oxidation. Under ultrasonic stimulation, it achieved a remarkable turnover number as high as 2402. Compared to inorganic ferroelectrics like lithium niobate (LiNbO3), the molecular ferroelectric exhibited a 1200-fold increase in catalytic activity. This highlights Cu-DFCBA's robust ferroelectric properties and underscores the vast potential of molecular ferroelectrics in catalysis, guiding future system designs.

Unique structural attributes of the PSI-NDH supercomplex in Physcomitrium patens.

Cyclic electron transport around photosystem I (PSI) is essential for the protection of the photosynthetic apparatus in plants under diverse light conditions. This process is primarily mediated by Proton Gradient Regulation 5 protein/Proton Gradient Regulation 5-like photosynthetic phenotype 1 protein (PGR5/PGRL1) and NADH dehydrogenase-like complex (NDH). In angiosperms, NDH interacts with two PSI complexes through distinct monomeric antennae, LHCA5 and LHCA6, which is crucial for its higher stability under variable light conditions. This interaction represents an advanced evolutionary stage and offers limited insight into the origin of the PSI-NDH supercomplex in evolutionarily older organisms. In contrast, the moss Physcomitrium patens (Pp), which retains the lhca5 gene but lacks the lhca6, offers a glimpse into an earlier evolutionary stage of the PSI-NDH supercomplex. Here we present structural evidence of the Pp PSI-NDH supercomplex formation by single particle electron microscopy, demonstrating the unique ability of Pp to bind a single PSI in two different configurations. One configuration closely resembles the angiosperm model, whereas the other exhibits a novel PSI orientation, rotated clockwise. This structural flexibility in Pp is presumably enabled by the variable incorporation of LHCA5 within PSI and is indicative of an early evolutionary adaptation that allowed for greater diversity at the PSI-NDH interface. Our findings suggest that this variability was reduced as the structural complexity of the NDH complex increased in vascular plants, primarily angiosperms. This study not only clarifies the evolutionary development of PSI-NDH supercomplexes but also highlights the dynamic nature of the adaptive mechanisms of plant photosynthesis.

Free‐Standing Ultrathin Films of 2D Perovskite for Light‐Emitting Devices Operating at Strong Coupling Regime

AbstractA novel and cost‐effective method for producing free‐standing polyimide films that support a layer of 2D polycrystalline perovskite is presented. This flexible structure can be easily transferred to different substrates of various sizes and roughness, as demonstrated by depositing it on a small dielectric mirror. The experiments confirm that the presence of polyimide thin film does not affect the optical properties of the 2D perovskite, maintaining its integrity under both ambient and cryogenic conditions. Furthermore, the flexible 2D perovskite within an optical microcavity, achieving strong light‐matter coupling at room temperature is successfully embedded. The findings not only extend the frontiers of flexible optoelectronics but also emphasize its importance in improving high‐performance light‐emitting devices.

Influence of Cataract Causing Mutations on αA-Crystallin: A Computational Approach.

The αA-crystallin protein plays a vital role in maintaining the refractive index and transparency of the eye lens. Significant clinical studies have emerged as the αA-crystallin is prone to aggregation, resulting in the formation of cataracts with varied etiologies due to mutations. This work aims to comprehend the structural and functional role of cataract-causing mutations in αA-crystallin, particularly at N-Terminal and α-Crystallin Domains, using in-silico approaches including molecular dynamics simulation. About 19 mutants of αA-crystallin along with native structure were simulated for 100 ns and the post-simulations analyses reveal pronounced dynamics of αA-crystallin due to the enhanced structure flexibility as its native compactness was lost and is witnessed mainly by the mutants R12L, R21L, R21Q, R54L, R65Q, R116C and R116H. It is observed that αA-crystallin discloses the NTD motions as the dominant one and the same was endorsed by the linear variation between Rg and the center-of-mass of αA-crystallin. Interestingly, such enhanced dynamics of αA-crystallin mutants associated with the structure flexibility is internally modulated by the dynamic exchange of secondary structure elements β-sheets and coils (R2 = 0.619) during simulation. Besides, the observed pronounced dynamics of dimer interface region (β3-L6-β4 segment) of ACD along with CTD dynamics also gains importance. Particularly, the highly dynamic mutants are also characterized by enhanced non-covalent and hydrophobic interactions which renders detrimental effects towards its stability, and favours possible protein unfolding mechanisms. Overall, this study highlights the mutation-mediated structural distortions in αA-crystallin and demands the need for further potential development of inhibitors against cataract formation.

Competition & UV254 projection in odorants vs natural organic matter adsorption onto activated carbon surfaces: Is the chemistry right?

Powdered activated carbon (PAC) adsorption remains an indispensable method for addressing odor problems in drinking water. While natural organic matter (NOM) is ubiquitous and competes strongly in deteriorating odorant adsorption capacity, it can also serve as a promising indicator for predicting odorant adsorption through online measurement. However, the impact of PAC surface chemistry on NOM competition and feasibility of prediction across various adsorbents are not well understood. Here, we examined the role of PAC properties (pore structure and surface chemistry) in the competitive adsorption between odorants and NOM components, aligned with the applicability assessment of using NOM optical properties for odorant adsorption projection across various PAC samples. Chemical oxidation and thermal treatment achieved considerable changes in surface functional group composition, alongside minimal changes in pore structure, of two typical PAC products with microporous/mesoporous pore characteristics. The effect of NOM interference on the reduction of odorant adsorption exhibited a similar level regardless of the PACs with different pore structure (average pore size of 1.7 nm vs. 4.2 nm). Surface modification increased the equilibrium adsorption capacity (qe50) of odorants by 15.1% to 146.4% (thermal treatment) or decreased by -81.3% to -34.1% (chemical oxidation), respectively, but minimal changes in odorant-NOM selectivity. For various odorants, hydrophobicity (log D) influenced the adsorption capacity while the structural flexibility (reflected by the rotatable bonds) affected the vulnerability of odorant adsorption to NOM competition. It was found for the first time that four-parameter Richards model (RMSE = 2.6%) is superior to the linear model (RMSE = 12.5%) or logarithmic model (RMSE = 77.6%) to describe the S-shape UV254 projection curves associated with odorant adsorption on PAC. Moreover, the feasibility was confirmed to use UV254 projection curves of pristine PAC fitted with the Richard model to predict the odorant adsorption on surface-modified PAC in two different surface waters (RMSE 9.2% and 7.4%, respectively). This study provides insight into the role of PAC surface chemistry and pore characteristics in odorant adsorption in NOM-containing waters and enhances the feasibility of the NOM surrogate model for odorant monitor and control during PAC adsorption.

Hyperspectral and multispectral images fusion based on pyramid swin transformer

Remote sensing image fusion aims to generate a high spatial resolution hyperspectral image (HR-HSI) by integrating a low spatial resolution hyperspectral image (LR-HSI) and a high spatial resolution multispectral image (HR-MSI). While Convolutional Neural Networks (CNNs) have been widely employed in addressing the HSI-MSI fusion problem, their limited receptive field poses challenges in capturing global relationships within the feature maps. On the other hand, the computational complexity of Transformers hinders their application, especially in dealing with high-dimensional data like hyperspectral images (HSIs). To overcome this challenge, we propose an HSI-MSI fusion method based on the Pyramid Swin Transformer (PSTF). The pyramid design of the PSTF effectively extracts multi-scale information from images. The Spatial-Spectral Crossed Attention (SSCA) module, comprising the Cross Spatial Attention (CSA) and the Spectral Feature Integration (SFI) modules. The CSA module employs a cross-shaped self-attention mechanism, providing greater modeling flexibility for different spatial scales and non-local structures compared to traditional convolutional layers. Meanwhile, the SFI module introduces a global memory block (MB) to select the most relevant low-rank spectral vectors, integrating global spectral information with local spatial–spectral correlation to better extract and preserve spectral information. Additionally, the Separate Feature Extraction (SFE) module enhances the network’s ability to represent image features by independently processing positive and negative parts of shallow features, thus capturing details and structures more effectively and preventing the vanishing gradient problem. Compared with the state-of-the-art (SOTA) methods, experimental results demonstrate the effectiveness of the PSTF method.

Monomer unfolding of a bacterial ESCRT-III superfamily member is coupled to oligomer disassembly.

The inner membrane associated protein of 30 kDa (IM30), a member of the endosomal sorting complex required for transport (ESCRT-III) superfamily, is crucially involved in the biogenesis and maintenance of thylakoid membranes in cyanobacteria and chloroplasts. In solution, IM30 assembles into various large oligomeric barrel- or tube-like structures, whereas upon membrane binding it forms large, flat carpet structures. Dynamic localization of the protein in solution, to membranes and changes of the oligomeric states are crucial for its in vivo function. ESCRT-III proteins are known to form oligomeric structures that are dynamically assembled from monomeric/smaller oligomeric proteins, and thus these smaller building blocks must be assembled sequentially in a highly orchestrated manner, a still poorly understood process. The impact of IM30 oligomerization on function remains difficult to study due to its high intrinsic tendency to homo-oligomerize. Here, we used molecular dynamics simulations to investigate the stability of individual helices in IM30 and identified unstable regions that may provide structural flexibility. Urea-mediated disassembly of the IM30 barrel structures was spectroscopically monitored, as well as changes in the protein's tertiary and secondary structure. The experimental data were finally compared to a three-state model that describes oligomer disassembly and monomer unfolding. In this study, we identified a highly stable conserved structural core of ESCRT-III proteins and discuss the advantages of having flexible intermediate structures and their putative relevance for ESCRT-III proteins.

The Platform trial In COVID-19 vaccine priming and BOOsting (PICOBOO) booster vaccination substudy protocol

BackgroundCoronavirus-2019 (COVID-19) vaccination in Australia commenced in February 2021. The first vaccines recommended for use were AZD1222 and BNT162b2, both delivered as a two-dose primary schedule. In the absence of sustained immunity following immunisation, recommendations for booster vaccination have followed. It is likely that periodic boosting will be necessary for at least some Australians, but it is unknown what the optimal booster vaccines and schedules are or for whom vaccination should be recommended.MethodsThe Platform Trial In COVID-19 priming and BOOsting (PICOBOO) is a multi-site, multi-arm, randomised, Bayesian adaptive platform trial evaluating different booster vaccine interventions in immunocompetent children and adults, stratified by their primary vaccination schedule and age. Participants are randomised to receive one of three licensed COVID-19 booster vaccines available for use in Australia. PICOBOO aims to generate evidence about the immunogenicity, reactogenicity, and cross-protection of different booster vaccine strategies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its variants/subvariants. The protocol structure specifying PICOBOO is modular and hierarchical. We have previously published the PICOBOO core (master) protocol. Here, we detail the substudy protocol which outlines the study processes which are specific to PICOBOO participants enrolled in the booster vaccination substudy.DiscussionPICOBOO is an adaptive platform trial evaluating different COVID-19 booster vaccination strategies to generate evidence to inform immunisation practice and policy. The modular and flexible protocol structure is intended to enable investigators to respond with agility to new research questions as they arise, such as immunogenicity targeting emergent virus variants, and the immunogenicity and reactogenicity of new vaccines as they become available for use.Trial registrationAustralian and New Zealand Clinical Trials Register ACTRN12622000238774; registered on 10/02/2022. Protocol V8.0_23112023.