Building Components Research Articles

Upscaling bio-based products: poplar and hemp for soil and building circular synergies

Abstract The paper illustrates the rationale of an ongoing research aimed at identifying innovative applications for poplar- and hemp-based products in constructive systems, focusing on load-bearing poplar plywood elements and hemp blocks and panels for the building envelope. The underlying approach extends the circular-based perspective from the building component scale to the territorial and economic one, adopting a context-wise approach. The potential of these renewable materials is examined beyond the application to reversible building systems, to depict their comprehensive contribution to a carbon-neutral region by examining the links with the local territorial management and a potential short supply chain. The contribution describes poplar and hemp agricultural productions, connecting their outputs to several economic sector. After addressing the environmental benefits, the two cultivations produce in terms of climate change mitigation and adaptation, among which carbon uptake, it contextualises poplar- and hemp-based products within current bio-based solutions in the building sector, exploring possible applications in new and existing constructions through circular constructive systems. The results discussion outlines the sustainable multiscale synergies supported by poplar- and hemp-based building products within the research perimeter.

Comprehensive analysis of thermal performance and low-grade energy charging efficiency of pipe-embedded building envelopes enhanced with single-level tree-shaped fin structures

Pipe-embedded walls (CnPWs) are structural and energy composite building components that can resist external disturbances by forming stealth thermal shielding layers. To tackle the mismatch between the heat charging rate and heat diffusion rate during energy charging processes, as well as the unsatisfactory robustness of stealth thermal shielding layers, the single-level tree-shaped metal finnd pipe-embedded walls (TfPWs) are proposed. To verify the effectiveness of TfPWs and obtain dynamic performances, a simulation study is conducted on 8 risk variables in 4 pairs through the validated numerical model. Results showed that the improved design was effective in obtaining more robust thermal shielding layers in auxiliary energy supply mode, the effect gained prominence as both the injection temperature and pipe spacing were augmented. In room heat load reduction mode, favorable benefits arise when pipe spacing exceeds 400 mm. The maximum increase rate of total injected energy under different reduction ratios of external insulation layer was 11.83%–31.91 %, while the maximum extra total heat loss was 5.33 %. Secondly, the trunk fins and branch fins played different roles in minimizing the excessive heat accumulation surrounding pipes, and the vertical and horizontal sizes of heat accumulation region mainly increased with the increase in trunk fin size and branch fin size respectively. Meanwhile, the utilization efficiency of fin material was higher when trunk fin size was smaller, and parameter combinations with trunk fin size of 0.2b and branch fin size of 0.4a/0.6a could achieve a better balance between material input and performance increase. Thirdly, the improvement effect of single left branch fin schemes was close to that of double branch fin schemes and significantly better than that of single right branch fin schemes. It was recommended to use single left branch fin schemes with an inclination angle of 60°. Finally, even if the reduction ratio of external insulation layer in different cities increased to 80 %, the inside surface temperature of TfPWs was still greater than room air. Taking CnPWs with standard external insulation layer as references, the TfPWs applied in Harbin, Beijing, and Shanghai could achieve similar or better results even when the reduction ratio of external insulation layer increased to 60 %, while TfPWs applied in Guangzhou could exhibit better performance even when the reduction ratio of external insulation layer increases to 80 %.

Demountable structures: evaluation of a circular design approach through life cycle assessment

Abstract The demand to reduce the use of raw materials, construction waste, and the negative environmental impacts of the construction sector is constantly increasing. New circular design strategies, such as Design for Disassembly, are intended to meet these challenges. Furthermore, circular strategies facilitate the easy and quick replacement of building components during end-of-life phases, as well as the efficient and waste-free deconstruction of entire buildings for subsequent reuse. However, building structures developed according to these strategies can have a higher environmental burden in the production or use phase of their life cycle. To confirm the actual environmental benefits of circular constructions, the paper utilizes the Life Cycle Assessment (LCA) method as a vital tool for the environmental evaluation of circular structures. As a case study, fully demountable and conventional masonry building façade systems with insulation are analyzed through a cradle-to-cradle approach over 2 life cycles. Several End-of-Life scenarios, as well as reuse and the benefits it provides, were considered during the assessment. Examining eight environmental indicators, the comparative analysis of linear and circular facade design approaches in the chosen case studies provides insights into efficient and environmentally friendly solutions.

The Impact of 3D Printing Technology on the Improvement of External Wall Thermal Efficiency—An Experimental Study

Three-dimensional printing technology continues to evolve, enabling new applications in manufacturing. Extensive research in the field of biomimetics underscores the significant impact of the internal geometry of building envelopes on their thermal performance. Although 3D printing holds great promise for improving thermal efficiency in construction, its full potential has yet to be realized, and the thermal performance of printed building components remains unexplored. The aim of this paper is to experimentally examine the thermal insulation characteristics of prototype cellular materials created using 3D additive manufacturing technologies (SLS and DLP). This study concentrates on exploring advanced thermal insulation solutions that could enhance the energy efficiency of buildings, cooling systems, appliances, or equipment. To this end, virtual models of sandwich composites with an open-cell foam core modeled after a Kelvin cell were created. They were characterized by a constant porosity of 0.95 and a pore diameter of the inner core of the composites of 6 mm. The independent variables included the different material from which the composites were made, the non-uniform number of layers in the composite (one, two, three, and five layers) and the total thickness of the composite (20, 40, 60, 80, and 100 mm). The impact of three independent parameters defining the prototype composite on its thermal insulation properties was assessed, including the heat flux (q) and the heat transfer coefficient (U). According to the experimental tests, a five-layer composite with a thickness of 100 mm made of soybean oil-based resin obtained the lowest coefficient with a value of U = 0.147 W/m2·K.

Out-BREAK!: An IDWeek 2023 Escape Room to Break Out of the Educational Mold.

An escape room is a cooperative game that has been adapted into medical education and major academic conferences. We describe the design, development, and implementation of an educational ID-themed escape room activity entitled "Out-BREAK!" at an international conference, IDWeek 2023. An anonymous survey was conducted to collect demographic data, assess participant satisfaction with the escape room puzzles, and gauge participant interest in game-based learning. Thirty escape room sessions were held over 3 days and included 201 participants. Escape room survey respondents (n = 132) were younger and more likely to be trainees compared with in-person IDWeek attendants. Among 131 responses, all respondents enjoyed the experience and would recommend the escape room activity to friends. Survey respondents enjoyed the puzzle solving (93%), medical content (92%), and team building (79%) components. Only 35% of the respondents had ever previously participated in game-based learning; 95% thought the escape room was a valuable teaching method. Among the 72 survey respondents involved in medical education, almost all (90%) said they were interested in incorporating escape rooms into medical education. The Out-BREAK! escape room at IDWeek 2023 was successfully implemented and well received. Despite only a third of participants having prior experience with game-based learning, almost all respondents perceived the escape room to be an effective teaching method.

LCA and economic cradle-to-gate analysis on the reuse of a temporary building.

In recent decades, the significant negative environmental impacts of the construction industry have caused a lot of concern, especially from the large number of temporary buildings required for mega projects. Reusing building components can help reduce pollution and preserve resources, but the economic and environmental effects are not well understood. This study has addressed the economic and environmental effects of reusing temporary building elements using life cycle assessment (LCA). The product system and functional unit in the current study is an office building equipment workshop with an area of 80 m2 and the system boundary is from cradle to gate. Life cycle assessment was accomplished using Simapro software and several life cycle assessment methods such as CML-la Baseline, BEES + , and IPCC was used to verify the results. The findings show that reusing disassembled building parts can reduce environmental damage by 79% and environmental damage costs by 77%. These results are important for construction managers seeking to make sustainable decisions that minimize environmental harm. Future research should expand the system boundary to include the entire building life cycle and apply the methodology to a wider range of building types and climates. Developing design guidelines for disassembly and reuse would also help promote sustainable construction practices. Overall, this study provides a robust framework for assessing the environmental and economic impacts of reusing building components, which is crucial for achieving sustainable development in the construction industry.

Parameters and barriers affecting the marketability of energy efficient residential buildings: a case study in Turkey

ABSTRACT The data indicate that merely improving energy efficiency within energy-efficient buildings (EEBs) is insufficient to significantly reduce the energy demand of the building sector. To achieve substantial reductions, strategies must also focus on increasing the number of EEBs within the existing building stock. However, research in this area remains limited. Therefore, this study aims to explore the current market demand and barriers for EEBs, examine the impact of various design decisions on housing prices, identify the factors influencing the marketability of residential buildings, and analyze customer purchasing decisions in Turkey (Türkiye). For this purpose, a comprehensive literature review was first made. It was observed that factors such as macroeconomic conditions, sales price, housing opportunities, location, brand, customer demographics, energy efficiency, housing features, and aesthetics were frequently discussed in the literature. Based on the literature review and preliminary study results, among other factors, aesthetic appreciation is considered the most applicable design strategy, and windows and balconies are identified as building components that can simultaneously affect energy efficiency, marketability, and aesthetics. Then, as a preliminary study to determine major marketing strategies, the housing marketing strategies were surveyed and analyzed from the real estate sector in different cities as provided in the advertisements posted on their websites. Furthermore, a comprehensive e-mail survey was conducted with 351 different real estate companies amongst 22 cities of Türkiye. Based on the findings, enhancing architectural designs could potentially elevate the perceived value of energy-efficient homes by up to 18% among consumers and this can increase the marketability.

Enhancing energy dissipation in mortar utilizing recycled brick fine aggregate impregnated with polymer emulsion under uniaxial cyclic load

Optimizing the damping properties of materials can enhance the energy dissipation capacity of structures and mitigate the negative effects of dynamic loads on building components. This study investigated the effects of the polymer emulsion-impregnated recycled brick fine aggregate (PRBFA) replacement rate, emulsion-impregnation treatment method, and emulsion solid content on the dynamic damping properties of PRBFA-prepared mortar (PBM). Combined with microscopic tests, the enhanced damping mechanism of PBM was discussed. The results show that under the same stress amplitude, the equivalent damping ratio and loss modulus of PBM increase with the PRBFA replacement rate and emulsion solid content. The drying treatment of PRBFA demonstrates superior damping characteristics of PBM, with the equivalent damping ratio and loss modulus increased by 84.9%–129.4 % and 71.0%–117.2 %, respectively, compared to those of PBM with undried PRBFA. The damping enhancement of PBM is attributed to the weak interface between the aggregate and cement matrix, which facilitates slippage and friction. The damping layer formed between the high viscoelastic emulsion and the aggregate, or between the emulsion and the cement matrix, is conducive to energy dissipation. The optimal PRBFA replacement rate for balancing the mechanical and damping properties of PBM is between 38% and 60 %.

Bi-YOLO: A novel object detection network and dataset for components of China heritage buildings

Amidst China's rapid urbanization, the preservation of cultural heritage amidst transformational rural redevelopment has emerged as a critical concern. This paper introduces a novel object detection network Bi-YOLO and dataset tailored to recognize components of China heritage buildings. Leveraging advancements in the specific dataset and object detection algorithms, the proposed tool offers a promising avenue for automating the identification and cataloging of traditional architectural elements essential for adaptive reuse projects. Through a case study, we demonstrate the practical application and efficacy of the proposed tool in facilitating rural building renovation endeavors. Ultimately, this research contributes to the discourse on sustainable development and cultural preservation by offering innovative methodologies for the adaptive reuse of traditional dwelling, thereby bridging the gap between traditional architectural research and cutting-edge deep learning techniques.

Development of a Generative Design System for 3D-Printed Houses in Chile

Three dimensional-printing construction is an emerging technology with significant potential for faster building execution and more precise, controllable designs. This technology utilizes material deposition managed by computer data, enabling additive construction of shapes. This research aims to develop a generative design system for 3D-printed houses in Chile, addressing the country’s growing demand for housing across diverse geographical locations and social groups, also present in other parts of the world. The development process involves synthesizing the external form features of existing Chilean houses and analyzing prototypes of 3D-printed houses worldwide to establish a set of geometric characteristics suitable for 3D-printed homes in Chile. A procedure is then outlined to create design alternatives using parametric programming on a BIM platform, followed by toolpath development for printing the building components. Various models are generated to demonstrate housing shapes’ versatility and adaptability to Chilean contexts and 3D-printed construction methods. Finally, a detailed design is created and printed to construct a housing prototype, testing the entire digital workflow. This experience highlights the variety of 3D-printed housing shapes that can be developed while assessing their feasibility for the Chilean context. This research complements the flexible design capabilities of 3D printing construction, resulting in buildings better suited to various locations and occupancy needs.

Additive manufacturing of interlocking glass masonry units

AbstractIn comparison to traditional glass casting, glass additive manufacturing (AM) presents an opportunity to increase design flexibility and reduce tooling costs for the production of highly variable geometries. While the latter has been extensively explored for masonry units, there is minimal research on the former for its viability to produce structural building components. This paper encompasses design, manufacturing, and experimental testing to assess the feasibility of using glass AM to produce interlocking masonry units for the construction industry. The glass 3D printer employed in this study is capable of printing a maximum volume of 32.5 $$\times $$ × 32.5 $$\times $$ × 38 cm–suitable for producing full-size masonry units. As part of this work, we discuss how to adapt design guidelines for glass AM to produce interlocking units. To evaluate fabrication ease and structural performance, three fabrication methods, Fully Hollow, Print-Cast, and Fully Printed, are compared. To compare the accuracy, repeatability, and structural capacity of each masonry unit, geometric analysis, surface roughness, and mechanical testing is conducted. Results varied by fabrication method, with average strength ranging from 3.64$$-$$ - 42.3 MPa for initial fracture and 64.0–118 MPa for ultimate strength. Accuracy in print dimensions was less than 1 mm with a standard deviation of 0.14–1.6 mm. Results demonstrated that Fully Hollow masonry units provide a more immediate path to implementation, while Fully Printed units have the potential to provide an entirely glass, transparent, and circular building component fabrication method.

A review of complex window-glazing systems for building energy saving and daylight comfort: Glazing technologies and their building performance prediction

The increasing energy consumption and detrimental CO2 emissions contributing to global warming underscore the urgent necessity for energy conservation, especially within buildings. Among different building components, fenestration plays a pivotal role as it accounts for the majority of heat transfer across the building envelope. This emphasises the significance of window-glazing technologies in enhancing their thermal performance. Furthermore, window-glazing systems can lead to overheating issues, particularly in summer, and glare issues, especially in winter. These challenges have spurred the development of various advanced glazing systems. This paper provides a comprehensive review of these advanced glazing technologies based on their functionalities and working principles, with a focus on parameters such as U-value, solar heat gain coefficient and visible transmittance. Among these technologies, vacuum and aerogel glazing systems exhibit superior thermal insulation properties, with U-values below 1 W/m2 K, making them suitable for heating-dominated climates. Smart window systems, such as electrochromic windows, are ideal for cooling-dominated climates due to their low solar heat gain coefficient (0.09–0.47) and visible transmittance (0.02–0.62). Photovoltaic window systems not only provide effective thermal insulation and solar shading but also produce additional power for on-site use. Some of these glazing systems feature complex structures, which present challenges when integrating them into existing building simulation software to assess their impact on building performance. Therefore, this paper also examines techniques for conducting energy and daylight performance simulations for buildings that make use of complex window systems. Ultimately, the authors propose an approach to characterise the thermal, optical and electrical properties of a complex photovoltaic window system within existing building simulation software, such as EnergyPlus. This approach facilitates a thorough investigation into the effects of complex window systems on building energy efficiency and indoor comfort.

Psychological Interventions and Those With Elements of Positive Psychology for Child and Youth Mental Health During the COVID-19 Pandemic: Literature Review, Lessons Learned, and Areas for Future Knowledge Dissemination.

There was a marked decline in child and teenage mental health worldwide during the pandemic, with increasing prevalence of depression, anxiety, and suicide. Research indicates that positive psychological interventions may be beneficial for mental health. The aims of this review were to evaluate positive psychological interventions for child and youth mental health implemented during the COVID-19 pandemic and assess overall effectiveness for mental health and knowledge. We undertook a literature search of PubMed, MEDLINE, and Google Scholar for all eligible studies on digital and hybrid in-person psychological interventions for youth mental health during the COVID-19 pandemic. A particular emphasis was placed on positive psychological interventions or interventions that had components of positive psychology, including gratitude, acceptance, positive emotions, or resilience building. A total of 41 interventions were included in this review. Most of the interventions were digital. Overall, most of the interventions assisted with one or more mental health or psychological indicators, such as depression, anxiety, posttraumatic stress disorder, stress, and resilience. However, findings were mixed when it came to targeting both depression and anxiety together. The interventions that promoted youth mental health most often had a range of diverse positive psychology components and were evidence based. Not all studies measured changes in mindfulness. Few studies examined knowledge acquired on mental health self-care, managing mental health problems, knowledge of positive psychological techniques, mindfulness knowledge, or mental health self-efficacy. Diverse multicomponent interventions appear to assist with youth mental health overall, although their effects on both depression and anxiety are less clear. There is also a need for more research on knowledge gains to determine whether the interventions improved knowledge on mental health-supportive behaviors, which may be sustained beyond the intervention. Finally, more studies need to evaluate whether the interventions assisted with increasing self-efficacy for practicing positive psychological techniques as well as changes in mindfulness levels. Future studies should not only assess effectiveness for mental health outcomes but also assess knowledge translation, with valid measures of knowledge and self-efficacy for mental health-supportive behaviors and positive psychological skills acquired (eg, the ability to practice mindfulness).

Environmental savings from concrete reuse: examining the limitations and optimal practices for cutting thresholds of concrete building components for reuse

Abstract Concrete, a widely used construction material, presents both opportunities and challenges for promoting environmentally responsible practices. This research focuses on the concept of concrete reuse as a sustainable strategy, examining the limitations of cutting dimensions. To investigate the greenhouse gas (GHG) emissions associated with preparing concrete for reuse, a mathematical model was developed considering several factors, such as transportation emissions, energy used in cutting, and the effects of varying cutting performance and energy sources. By incorporating real-life data and connecting with industrial practices, this study establishes a screening standard to determine the minimum cutting size for concrete reuse. The results indicate that the ratio of transportation distances for the reuse case versus the new production of concrete case has an influence on the minimum cutting size for concrete reuse. Moreover, the cutting size itself significantly impacts the overall GHG emissions of the reuse strategy. We offer practical insights for industry stakeholders to optimize concrete reuse practices and effectively reduce GHG emissions. As further research explores cost-effectiveness and on-site case studies, the potential for large-scale implementation of concrete reuse has become increasingly promising. Thus, concrete reuse has emerged as a viable and effective approach to sustainable construction, provided that the minimum cutting dimensions are carefully considered.

A comprehensive benchmark dataset for the validation of building component heat, air, and moisture (HAM) models

A comprehensive benchmark dataset for the validation of building component heat, air, and moisture (HAM) models

Investigation of local buckling behavior of web perforated plain channel stub columns

As a sustainable material, cold-formed steel (CFS) is increasingly popular in structural components of buildings and industrial storage racks. The plain channel sections having a flange stiffened web element and unstiffened flange elements are prominently used as compression members in CFS systems. These elements are likely to undergo local buckling under compressive loading. The openings or closely spaced perforations along the longitudinal direction of the web for serviceability requirements on buildings and beam level adjustment requirements on storage racks lead to additional complications to the local buckling. Although the Effective Width Method and Direct Strength Method rationally cover the buckling behavior of plain channel sections, the influence of height-to-width ratio with perforations is not effectively accounted for in the design. Limited research details are available in the literature for the web perforations of lipped channels or rack sections. However, these sections do not have unstiffened flanges, where the unstiffened flanges can be more vulnerable to local buckling, e.g., plain channels. The web perforations also make the web more vulnerable to local buckling. This article examines the local buckling behavior of plain channel sections with the influence of web perforations through systematic experimental and comprehensive numerical studies. The influencing parameters of the cross-section geometry are assessed through the principal component analysis (PCA) to understand its correlation with local buckling. The PCA results shed light on mandatory parameters for the elastic critical local buckling load calculation and/or nominal local buckling strength prediction of the plain channel section.

Numerical modelling of global/local mechanisms and sensitivity analysis for the seismic vulnerability assessment of glass curtain walls

Façades represent complex and vulnerable components for buildings, due to the intrinsic fragility and brittleness of glass, and require specific design and calculation tools, both for ordinary and extreme design loads. In this context, the availability of consolidated and strategic modelling strategies is of utmost importance for structural safety considerations and optimal decisions. In this paper, the attention is focused on the assessment of different modelling strategies for the global and local behaviour analysis of Glass Curtain Walls (GCWs) under in-plane seismic loads. Benefits and limitations are discussed for a more refined (but expensive, “MREF”) and a simplified (and computationally efficient, but weak in capturing local phenomena, “MSIMP”) model assemblies developed in ABAQUS and SAP2000, respectively. Careful consideration is given for typical mechanisms, local responses, key performance indicators for the façade components (i.e., stress and deformation peaks) for a reference GCW under monotonic and cyclic loads, as well as for major effects due to general input parameters (i.e., contact mechanisms, clearance, friction, bare frame features, secondary components, etc.), based on a parametric sensitivity investigation. The parametric comparative results are critically discussed, with the support of an experimental prototype test from literature, and the most influencing parameters are emphasized, to improve and facilitate the development of further design and modelling optimization strategies.

Strengthening of Vaccine-Preventable Disease (VPD) Surveillance to Enhance National Health Capacity and Security: Perspective from India.

The Government of India, in collaboration with the World Health Organization (WHO), established the National Polio Surveillance Project (NPSP) in 1997 and initiated acute flaccid paralysis (AFP) surveillance to achieve the goal of polio eradication. The WHO South-East Asia Region, comprising of 11 countries, including India, was certified as polio-free in March 2014. India was also validated to have eliminated maternal and neonatal tetanus in May 2015. Over the years, the surveillance of other vaccine-preventable diseases (VPDs) was integrated with AFP surveillance in the country. Outbreak-based measles-rubella (MR) surveillance was initiated in 2005 using AFP surveillance as a platform, case-based fever-rash (FR) surveillance started in 2021 as one of the strategies to achieve measles and rubella elimination in the country. The surveillance of diphtheria, pertussis, and neonatal tetanus was integrated with AFP surveillance in a phased manner during 2015-2022. The surveillance system for VPDs in India, supported by a laboratory network of 10 polio laboratories, 28 measles-rubella laboratories, and 20 diphtheria-pertussis laboratories, has enhanced the national health capacity and security. The setting up and expansion of the surveillance system in the country involved the important component of capacity building of personnel on various components of surveillance, including case identification, case investigation, sample collection and shipment, data analysis and public health response. These capacities have been used effectively during other emergencies, such as the recent COVID-19 pandemic, as well as during outbreaks of other diseases and natural calamities.

A synergetic self-sealing model for cement-based composite using granular expansive agent and crystalline admixture

The autogenous self-sealing model has been researched in previous work, which could help to characterize the self-sealing process with crystalline products. The model outcome was presented in the form of leakage water flow, which demonstrates the self-sealing capacity or the recovery of watertightness. While in the research area of cement-based material self-sealing, the expansive agent cannot be neglectable, for example the superabsorbent polymer (SAP). Especially for the building components exposed to free water, an efficient water flow blockage after cracking is crucial to ensure stable service. Hence in this study, the self-sealing process of a granular expansive agent inside the crack of cement-based material was simulated. The model outputs were compared with experimental results to verify the reliability. Additionally, the autogenous self-sealing model was incorporated into this model to simulate the “crystallization-expansion” synergetic self-sealing. The contribution of crystalline product and expanded EA to water flow blockage were compared during the crystallizing process. Overall, this model is of great use to evaluate the role of expansive agent on water flow blockage after the cement-based material cracking in hydraulic engineering or engineering components exposed to water.

Unlocking the nutritional potential: amino acid profile of eight Indian food fishes and their role in meeting recommended dietary allowances

IntroductionProteins and amino acids, as vital biomolecules, are not only part of key metabolic pathways in the body but are also essential for tissue repair, enzyme function, and hormone regulation. They also serve as building blocks for the formation of signaling molecules, such as neurotransmitters and catecholamines. Additionally, amino acids are the primary building components of proteins. Fish serves as a vital source of high-quality animal protein and amino acids, playing a crucial role in supporting human nutrition.MethodsHigh-performance liquid chromatography (HPLC) using fluorescence detector was employed to investigated the amino acid content of eight food fishes from diverse aquatic habitats.ResultsThe study revealed that the small indigenous fish (SIF) Systomus sarana and the marine fish Sardinella melanura were rich sources of all essential amino acids. Furthermore, estuarine fish like Pisodonophis boro can be recommended for specific amino acids like arginine, histidine, leucine, and valine, while Setipinna phasa is suggested for cysteine.DiscussionThese recommendations rely on the possible contribution of these fishes to the Recommended Dietary Allowance (RDA) regarding each nutrient. The insights gained from this study could be utilized as recommendations to meet amino acid requirement using fish as a natural supplement.