Structural Elements Research Articles

OpenFold: retraining AlphaFold2 yields new insights into its learning mechanisms and capacity for generalization.

AlphaFold2 revolutionized structural biology with the ability to predict protein structures with exceptionally high accuracy. Its implementation, however, lacks the code and data required to train new models. These are necessary to (1) tackle new tasks, like protein-ligand complex structure prediction, (2) investigate the process by which the model learns and (3) assess the model's capacity to generalize to unseen regions of fold space. Here we report OpenFold, a fast, memory efficient and trainable implementation of AlphaFold2. We train OpenFold from scratch, matching the accuracy of AlphaFold2. Having established parity, we find that OpenFold is remarkably robust at generalizing even when the size and diversity of its training set is deliberately limited, including near-complete elisions of classes of secondary structure elements. By analyzing intermediate structures produced during training, we also gain insights into the hierarchical manner in which OpenFold learns to fold. In sum, our studies demonstrate the power and utility of OpenFold, which we believe will prove to be a crucial resource for the protein modeling community.

Benzamide Trimethoprim Derivatives as Human Dihydrofolate Reductase Inhibitors—Molecular Modeling and In Vitro Activity Study

Human dihydrofolate reductase (hDHFR) is an essential cellular enzyme, and inhibiting its activity is a promising strategy for cancer therapy. We have chosen the trimethoprim molecule (TMP) as a model compound in our search for a new class of hDHFR inhibitors. We incorporated an amide bond, a structural element typical of netropsin, a ligand that binds selectively in the minor groove of DNA, into the molecules of TMP analogs. In this work, we present previously obtained and evaluated eleven benzamides (JW1–JW8; MB1, MB3-MB4). Recently, these compounds were specifically projected as potential inhibitors of the enzymes acetylcholinesterase (AChE) and β-secretase (BACE1). JW8 was most active against AChE, with an inhibitory concentration of AChE IC50 = 0.056 µM, while the IC50 for donepezil was 0.046 µM. This compound was also the most active against the BACE1 enzyme. The IC50 value was 9.01 µM compared to that for quercetin, with IC50 = 4.89 µM. All the benzamides were active against hDHFR, with IC50 values ranging from 4.72 to 20.17 µM, and showed activity greater than TMP (55.26 µM). Quantitative results identified the derivatives JW2 and JW8 as the most promising. A molecular modeling study demonstrates that JW2 interacts strongly with the key residue Gly-117, while JW8 interacts strongly with Asn-64 and Arg-70. Furthermore, JW2 and JW8 demonstrate the ability to stabilize the hDHFR enzyme, despite forming fewer hydrogen bonds with the protein compared to reference ligands. It can be concluded that this class of compounds certainly holds great promise for good active leads in medicinal chemistry.

The relationship between conctere composition and structural stability in case of fire

A series of disasters caused by fire have made engineers aware that understanding the consequences of fire is essential, as human lives depend on it, and it can also cause significant material damage. The structural integrity of structures during and after a fire, including their stability, can be better ensured if we accurately understand the effects of fire. Of course, the effects of fire do not always lead to significant damage, but in many cases they do. Fire protection is intended, on the one hand, to ensure that buildings remain stable under fire for a certain period, which is necessary to enable occupants to escape safely and, on the other hand, to minimize damage to building structures. The concrete composition, i.e., the structure's microstructure, significantly influences the stability of reinforced concrete structures in the event of fire or heat. In the case of concrete, in addition to changes in the internal material structure in the event of fire, spalling has also appeared recently, largely due to the denser concrete structure. In summary, the higher strength of concrete and the concomitant change in the test strength will lead to spalling, which will have a major impact on the stability of structures under fire. Both small-element (fiber efficiency, aggregate efficiency) and large-element tests have been carried out to verify this. The small-element tests were carried out in an electric furnace to monitor possible concrete surface delamination and strength loss. The small-element tests can be used to select concrete compositions for the large-element tests. Based on their experimental results, an increase in the fire resistance limit of a structural element can be achieved by reducing the delamination of the concrete surface when plastic fibers are added to the concrete. However, if a further increase in the fire resistance limit is required, a change in the type of cement or a modification of the supplementary material may be necessary to increase the residual strength value. Overall, the microstructure of concrete has a significant impact on the stability of structures in the event of a fire.

ASSESSING THE IMPACT OF ENGINEERED WOOD PRODUCTS ON SUSTAINABLE CONSTRUCTION: A COMPARATIVE STUDY WITH CONVENTIONAL CONCRETE BUILDING METHODS

Renewable-sourced EWPs offer enhanced dimensional stability, durability, and mechanical properties, facilitating larger and more complex structural elements, and contributing to faster construction times and better energy performance. The research investigates the feasibility and effectiveness of Engineered Wood Products (EWPs) as sustainable building materials in the construction sector by a comparison of their cost, performance, and environmental impact against conventional concrete. The research emphasises the importance of innovative design, recycling, and waste reduction in fostering sustainable construction methods that satisfy the demands of present and future generations while conserving energy. However, there are negative environmental impacts linked to the production of concrete, such as habitat destruction, atmospheric emissions, and waste generation. The research adopted a web-based survey to gather quantitative data from construction experts. The Relative Importance Index (RII) was adopted to analyze the respondents' perceptions of the benefits of EWP and concrete negative effects. The results of the research reflect respondents' significant preference for EWPs and are consistent with their outstanding environmental qualities. In conclusion, this paper argues that EWPs possess the potential to effectively revolutionise the construction industry by minimising its carbon footprint and encouraging sustainable construction practices that are required for addressing the expectations of both the present and the future.

Phytochemical evaluation of Ziziphus mucronata and Xysmalobium undulutum towards the discovery and development of anti-malarial drugs

BackgroundThe development of resistance by Plasmodium falciparum is a burdening hazard that continues to undermine the strides made to alleviate malaria. As such, there is an increasing need to find new alternative strategies. This study evaluated and validated 2 medicinal plants used in traditional medicine to treat malaria.MethodsInspired by their ethnobotanical reputation of being effective against malaria, Ziziphus mucronata and Xysmalobium undulutum were collected and sequentially extracted using hexane (HEX), ethyl acetate (ETA), Dichloromethane (DCM) and methanol (MTL). The resulting crude extracts were screened for their anti-malarial and cytotoxic potential using the parasite lactate dehydrogenase (pLDH) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, respectively. This was followed by isolating the active compounds from the DCM extract of Z. mucronata using silica gel chromatography and structural elucidation using spectroscopic techniques (NMR: 1H, 12C, and DEPT). The active compounds were then targeted against P. falciparum heat shock protein 70–1 (PfHsp70-1) using Autodock Vina, followed by in vitro validation assays using ultraviolet–visible (UV–VIS) spectroscopy and the malate dehydrogenase (MDH) chaperone activity assay.ResultsThe extracts except those of methanol displayed anti-malarial potential with varying IC50 values, Z. mucronata HEX (11.69 ± 3.84 µg/mL), ETA (7.25 ± 1.41 µg/mL), DCM (5.49 ± 0.03 µg/mL), and X. undulutum HEX (4.9 ± 0.037 µg/mL), ETA (17.46 ± 0.024 µg/mL) and DCM (19.27 ± 0.492 µg/mL). The extracts exhibited minimal cytotoxicity except for the ETA and DCM of Z. mucronata with CC50 values of 10.96 and 10.01 µg/mL, respectively. Isolation and structural characterization of the active compounds from the DCM extracts revealed that betulinic acid (19.95 ± 1.53 µg/mL) and lupeol (7.56 ± 2.03 µg/mL) were responsible for the anti-malarial activity and had no considerable cytotoxicity (CC50 > µg/mL). Molecular docking suggested strong binding between PfHsp70-1, betulinic acid (− 6.8 kcal/mol), and lupeol (− 6.9 kcal/mol). Meanwhile, the in vitro validation assays revealed the disruption of the protein structural elements and chaperone function.ConclusionThis study proves that X undulutum and Z. mucronata have anti-malarial potential and that betulinic acid and lupeol are responsible for the activity seen on Z. mucronata. They also make a case for guided purification of new phytochemicals in the other extracts and support the notion of considering medicinal plants to discover new anti-malarials.

Criteria for granting access by an EU member state to a severely ill patient to an unauthorized medicine

The article focuses attention on the fact that a structural element of everyone's subjective legal right to medical care is the right to access to a medicinal product. It is emphasized that the Covid-19 pandemic, the increase in the spectrum of incurable diseases and the number of patients suffering from them, Russia's aggression against Ukraine, the consequences of which are an increase in the number of military personnel and civilians who need the use of medicinal products created using the latest technologies, but which (medicines) are still not allowed in the state, the integration of Ukraine with the EU became the factors that actualized the discussion of scientists and practitioners on the issue of the conditions that must be observed by the EU member state in order to apply the provisions of Article 1. 5 of Directive 2001/83/EC of the European Parliament and of the Council on the Community Code regarding medicinal products intended for human use, the exception is to provide an EU member state with access to a patient to a medicinal product not authorized by the competent authorities of such a member state and thereby fulfill its obligation to provide everyone's constitutional right to medical care. The conditions that must be observed by the EU member state in order to apply the provisions of Article 1. 5 of the Exclusion Directives - for an EU member state to provide a patient with access to a medicinal product that is not authorized by the competent authorities of such a member state: 1) the presence of a norm of national law that allows the supply of a medicinal product for which a permit was not granted; 2) the goal is to meet the special needs of a specific seriously ill patient (private interest) and ensure the protection of public health (public interest); 3) be due to the absence on the national market of any authorized medicinal product - the equivalent of an unauthorized medicinal product; 4) delivery is made in response to a bona fide order on one's own initiative; 5) supply is carried out according to the prescription in accordance with the specifications of the authorized medical worker; 6) an unauthorized medicinal product is prescribed for use by a specific patient under his direct personal responsibility. The signs of the patient's special needs are highlighted: 1) the specific situation of the patient's state of health and the course of his illness; 2) medical reasoning, which is justified; 3) the patient's need for a certain medicinal product. The grounds for an unregistered medicinal product to be prescribed by a doctor are: the doctor's therapeutic considerations; results of research, analyzes of the patient. In a situation where there are authorized medicinal products on the market of an EU member state - analogues of prohibited medicinal products - the import of unauthorized medicinal products can be qualified as an act of non-fulfillment by the EU member state of its obligations, provided for in Article 1. 6 Directives.

C(sp)-C(sp) Lever-Based Targets of Orientational Chirality: Design and Asymmetric Synthesis

In this study, the design and asymmetric synthesis of a series of chiral targets of orientational chirality were conducted by taking advantage of N-sulfinylimine-assisted nucleophilic addition and modified Sonogashira catalytic coupling systems. Orientational isomers were controlled completely using alkynyl/alkynyl levers [C(sp)-C(sp) axis] with absolute configuration assignment determined by X-ray structural analysis. The key structural element of the resulting orientational chirality is uniquely characterized by remote through-space blocking. Forty examples of multi-step synthesis were performed, with modest to good yields and excellent orientational selectivity. Several chiral orientational amino targets are attached with scaffolds of natural and medicinal products, showing potential pharmaceutical and medical applications in the future.

Crop Phenology Estimation in Rice Fields Using Sentinel-1 GRD SAR Data and Machine Learning-Aided Particle Filtering Approach

Abstract. Monitoring crop phenology is essential for managing field disasters, protecting the environment, and making decisions about agricultural productivity. Because of its high timeliness, high resolution, great penetration, and sensitivity to specific structural elements, synthetic aperture radar (SAR) is a valuable technique for crop phenology estimation. Particle filtering (PF) belongs to the family of dynamical approach and has the ability to predict crop phenology with SAR data in real time. The observation equation is a key factor affecting the accuracy of particle filtering estimation and depends on fitting. Compared to the common polynomial fitting (POLY), machine learning methods can automatically learn features and handle complex data structures, offering greater flexibility and generalization capabilities. Therefore, incorporating two ensemble learning algorithms consisting of support vector machine regression (SVR), random forest regression (RFR), respectively, we proposed two machine learning-aided particle filtering approaches (PF-SVR, PF-RFR) to estimate crop phenology. One year of time-series Sentinel-1 GRD SAR data in 2017 covering rice fields in Sevilla region in Spain was used for establishing the observation and prediction equations, and the other year of data in 2018 was used for validating the prediction accuracy of PF methods. Four polarization features (VV, VH, VH/VV and Radar Vegetation Index (RVI)) were exploited as the observations in modeling. Experimental results reveals that the machine learning-aided methods are superior than the PF-POLY method. The PF-SVR exhibited better performance than the PF-RFR and PF-POLY methods. The optimal outcome from PF-SVR yielded a root-mean-square error (RMSE) of 7.79, compared to 7.94 for PF-RFR and 9.1 for PF-POLY. Moreover, the results suggest that the RVI is generally more sensitive than other features to crop phenology and the performance of polarization features presented consistent among all methods, i.e., RVI＞VV＞VH＞VH/VV. Our findings offer valuable references for real-time crop phenology monitoring with SAR data.

Missing Landscapes: A Geohistory of Parkland Landscapes in Northwestern Morocco

Northwestern Morocco is characterized by highly anthropized landscapes under the combined effect of agricultural intensification, resource overexploitation, urbanization, and tourism, but also local reforestation. Reconstructing the recent changes in vegetation in the region of the lower valley of the Loukkos river near Larache and their relationship to the settlement history are particularly helpful for understanding the processes at work within the landscape construction. The geohistorical approach combines paleoenvironmental, documentary, and historical data. The last few centuries have seen the emergence of wooded stands, in which cork oaks are a structural element. As forests were retreating, parklands intended for agriculture, agroforestry, and herding, like the Spanish dehesa and Portuguese montado, began to emerge. Nearly all of them have disappeared today, but we can identify their legacy and evaluate their cultural significance through comparing them with their counterparts in the Iberian Peninsula, but also in other areas of Morocco. Their deep historical roots give this landscape an evolving heritage character that is directly linked to the communities’ lifestyles, culture, and history.

Decoding bovine coronavirus immune targets: an epitope informatics approach

Bovine coronavirus (BCoV) poses a significant threat to the global cattle industry, causing both respiratory and gastrointestinal infections in cattle populations. This necessitates the development of efficacious vaccines. While several inactivated and live BCoV vaccines exist, they are predominantly limited to calves. The immunization of adult cattle is imperative for BCoV infection control, as it curtails viral transmission to calves and ameliorates the impact of enteric and respiratory ailments across all age groups within the herd. This study presents an in silico methodology for devising a multiepitope vaccine targeting BCoV. The spike glycoprotein (S) and nucleocapsid (N) proteins, which are integral elements of the BCoV structure, play pivotal roles in the viral infection cycle and immune response. We constructed a remarkably effective multiepitope vaccine candidate specifically designed to combat the BCoV population. Using immunoinformatics technology, B-cell and T-cell epitopes were predicted and linked together using linkers and adjuvants to efficiently trigger both cellular and humoral immune responses in cattle. The in silico construct was characterized, and assessment of its physicochemical properties revealed the formation of a stable vaccine construct. After 3D modeling of the vaccine construct, molecular docking revealed a stable interaction with the bovine receptor bTLR4. Moreover, the viability of the vaccine’s high expression and simple purification was demonstrated by codon optimization and in silico cloning expression into the pET28a (+) vector. By applying immunoinformatics approaches, researchers aim to better understand the immune response to bovine coronavirus, discover potential targets for intervention, and facilitate the development of diagnostic tools and vaccines to mitigate the impact of this virus on cattle health and the livestock industry. We anticipate that the design will be useful as a preventive treatment for BCoV sickness in cattle, opening the door for further laboratory studies.

Leveraging Deep Learning for Automated Reconstruction of Indoor Unstructured Elements in Scan-to-BIM

Abstract. Achieving automatic 3D reconstruction for indoor scenes is extremely useful in the field of scene understanding. Building information modeling (BIM) models are essential for lowering project costs, assisting in building planning and renovations, as well as improving building management efficiency. However, nearly all current available scan-to-BIM approaches employ manual or semi-automatic methods. These approaches concentrate solely on significant structured objects, neglecting other unstructured elements such as furniture. The limitation arises from challenges in modeling incomplete point clouds of obstructed objects and capturing indoor scene details. Therefore, this research introduces an innovative and effective reconstruction framework based on deep learning semantic segmentation and model-driven techniques to address these limitations. The proposed framework utilizes wall segment recognition, feature extraction, opening detection, and automatic modeling to reconstruct 3D structured models of point clouds with different room layouts in both Manhattan and non-Manhattan architectures. Moreover, it provides 3D BIM models of actual unstructured elements by detecting objects, completing point clouds, establishing bounding boxes, determining type and orientation, and automatically generating 3D BIM models with a parametric algorithm implemented into the Revit software. We evaluated this framework using publicly available and locally generated point cloud datasets with varying furniture combinations and layout complexity. The results demonstrate the proposed framework's efficiency in reconstructing structured indoor elements, exhibiting completeness and geometric accuracy, and achieving precision and recall values greater than 98%. Furthermore, the generated unstructured 3D BIM models keep essential real-scene characteristics such as geometry, spatial locations, numerical aspects, various shapes, and orientations compared to literature methods.

Classification of Scientific Papers based on their Nature and Format

The effective categorization and classification of scientific papers based on their nature and format are vital due to the extensive volume of published scientific literature. This research endeavors to delve into the intricate realm of classifying scientific papers, concentrating on discerning categories such as dissertations, scientific articles, theses, and other pertinent types. By meticulously examining the unique attributes, objectives, and structural elements inherent in each paper type, this study aims to furnish researchers, students, and readers with a comprehensive comprehension of the diverse assortment of scientific papers and their idiosyncratic features. Moreover, this article deliberates upon the significance of accurate classification with regard to proficient literature retrieval, knowledge dissemination, and academic publication. Additionally, it scrutinizes the conceivable challenges and deliberations involved in formulating classification systems for scientific papers, encompassing the dynamic nature of scientific communication and the emergence of alternative formats such as preprints and data papers. By augmenting our grasp of scientific paper classification, this research contributes to the enhancement of accessibility, organization, and utilization of scientific knowledge.

Studies of Fractal Microstructure in Nanocarbon Polymer Composites

The in situ study of fractal microstructure in nanocarbon polymers is an actual task for their application and for the improvement in their functional properties. This article presents a visualization of the bulk structural features of the composites using pulsed acoustic microscopy and synchrotron X-ray microtomography. This article presents details of fractal structure formation using carbon particles of different sizes and shapes—exfoliated graphite, carbon platelets and nanotubes. Individual structural elements of the composite, i.e., conglomerations of the particles in the air capsule as well as their distribution in the composite volume, were observed at the micro- and nanoscale. We have considered the influence of particle architecture on the fractal formation and elastic properties of the composite. Acoustic and X-ray imaging results were compared to validate the carbon agglomeration.

Online self-disclosure: An interdisciplinary literature review of 10 years of research

The term “self-disclosure” refers to actions by which individuals reveal information about themselves. The interest in such conduct has resurged with the development of networked participatory technologies, which enable creation, dissemination, analysis, and use of large amounts of personal information, thereby increasingly augmenting the effect of online self-disclosure on disclosers and disclosees. This article reviews 309 empirical studies about online self-disclosure published between 2010 and 2020 and aggregates insights thereof into an overarching model describing the ways in which this socio-technical undertaking unfolds. The review shows that online self-disclosure research overwhelmingly focuses on the individual and de-emphasizes structural elements that influence these practices and their outcomes. Based on these findings, we propose a structurational framework centered on the dialectic relationship between individuals and structures involved in self-disclosure and affected by such behaviors. This approach provides a useful tool to address the recent transformations of self-disclosure and its implications in the wake of computer-mediated technological developments.

Development prospects for production of filtration equipment in the Russian Federation at the present stage

The article examines the challenges caused by changes in the global situation that the production of filtration equipment faced. The equipment is used for the petrochemical complex. The article assesses prospects for technological independence in the petrochemical complex, including the auxiliary market of filtration and separation equipment. The article provides a statistical analysis of the indicators of the Russian filtration sector and analyses the applied filtration and separation methods in a comparative manner. To determine the prospects of companies producing the corresponding equipment and its individual structural elements, the method of situational analysis was used, with the help of which the features of products manufactured at the present stage that influence the development of business in this economic segment are identified. With the method of economic forecasting, the perspective position of domestic manufacturers in the filtration market was determined. With consideration to the modern developments in the field of industry management and to the given basic concepts used in the management of western companies, the possible ways of introduction of advanced managerial decisions were proposed. It is done in order to improve the position of domestic producers, to develop business and to switch to a new level of product improvement, process optimisation, continuous development of companies’ approaches, and thus respond quickly to the emerging challenges.

Mechanistic Insights Behind the Self-Assembly of Human Insulin under the Influence of Surface-Engineered Gold Nanoparticles.

Elucidating the underlying principles of amyloid protein self-assembly at nanobio interfaces is extremely challenging due to the diversity in physicochemical properties of nanomaterials and their physical interactions with biological systems. It is, therefore, important to develop nanoscale materials with dynamic features and heterogeneities. In this work, through engineering of hierarchical polyethylene glycol (PEG) structures on gold nanoparticle (GNP) surfaces, tailored nanomaterials with different surface properties and conformations (GNPs-PEG) are created for modulating the self-assembly of a widely studied protein, insulin, under amyloidogenic conditions. Important biophysical studies including thioflavin T (ThT) binding, circular dichroism (CD), surface plasmon resonance (SPR), and atomic force microscopy (AFM) showed that higher-molecular weight GNPs-PEG triggered the formation of amyloid fibrils by promoting adsorption of proteins at nanoparticle surfaces and favoring primary nucleation rate. Moreover, the modulation of fibrillation kinetics reduces the overall toxicity of insulin oligomers and fibrils. In addition, the interaction between the PEG polymer and amyloidogenic insulin examined using MD simulations revealed major changes in the secondary structural elements of the B chain of insulin. The experimental findings provide molecular-level descriptions of how the PEGylated nanoparticle surface modulates protein adsorption and drives the self-assembly of insulin. This facile approach provides a new avenue for systematically altering the binding affinities on nanoscale surfaces by tailoring their topologies for examining adsorption-induced fibrillogenesis phenomena of amyloid proteins. Together, this study suggests the role of nanobio interfaces during surface-induced heterogeneous nucleation as a primary target for designing therapeutic interventions for amyloid-related neurodegenerative disorders.

Comparison Regarding the Carbon Footprint of Various Sustainable Seismic Consolidation Solutions for Romanian Orthodox Churches

In Romania, there are numerous Orthodox churches, many of which are historical monuments of great cultural value that have suffered multiple degradations over time due to various natural or man-made reasons. In a context that is currently increasingly focused on environmental protection, we aim to analyse the carbon footprint of several different consolidation proposals to an Orthodox church with structural deteriorations (and more) and the equivalent impact if a similar building were erected with new materials. The research is proposed to be a stepping stone for determining the sustainability of interventions for orthodox churches, as the existing literature is scarce when it comes to the emissions of these churches and there is no norm to prevent unsustainable interventions. The Orthodox Church “Sfintii Voievozi”, the subject of the analysis, is in the city of Tg. Jiu, Gorj County. The construction was documented to be between 1748 and 1764 and is a historical monument listed in the LMI GJ-II-m-A-09189 registry. The architectural solutions for the church and the structural elements that comprise the load-bearing system are presented. A detailed investigation was conducted to determine structural and non-structural degradations, specifying the main causes that have produced them. With regard to consolidation solutions, two options are presented and compared in this paper: Alternative I—minimal intervention and Alternative II—maximal intervention, both of which are reversible. The carbon footprint calculation was carried out for both options, determining the associated material consumption, and compared to the carbon footprint for the case of a new construction. In conclusion, the consolidation methods with a minimal degree of intervention is recommended as the “most environmentally friendly”, considering carbon emissions when comparing the options.

Diversifying de novo TIM barrels by hallucination.

De novo protein design expands the protein universe by creating new sequences to accomplish tailor-made enzymes in the future. A promising topology to implement diverse enzyme functions is the ubiquitous TIM-barrel fold. Since the initial de novo design of an idealized four-fold symmetric TIM barrel, the family of de novo TIM barrels is expanding rapidly. Despite this and in contrast to natural TIM barrels, these novel proteins lack cavities and structural elements essential for the incorporation of binding sites or enzymatic functions. In this work, we diversified a de novo TIM barrel by extending multiple βα-loops using constrained hallucination. Experimentally tested designs were found to be soluble upon expression in Escherichia coli and well-behaved. Biochemical characterization and crystal structures revealed successful extensions with defined α-helical structures. These diversified de novo TIM barrels provide a framework to explore a broad spectrum of functions based on the potential of natural TIM barrels.

SUBSTANTIATION OF THE PONTOON-CABLE BRIDGE STRUCTURE FROM THE TENSEGRITY CONCEPT POINT OF VIEW

Purpose. The purpose of this work is to conduct an analysis of the tensegrity concept implementation, as well as the study of already built structures and those that are currently being designed according to this principle. Also to determine main features and characteristics of tensegrity structures and to consider the previously proposed structure of the pontoon-cable bridge from the point of view of this concept. Based on the analyzed data, it is proposed to develop alternative designs of the pontoon-cable bridge. Methodology. Analysis of literary sources, data on constructed and designed bridges and other structures; analysis and synthesis of building structures elements. Findings. Based on the studied data, the main features of tensegrity, as well as the principles of numerical analysis of structures to calculate some quantitative indicators of such systems, were determined. Conclusions were made about the formal non-compliance of both the built bridges and other structures, as well as the pontoon-cable bridge with tensegrity concept. Based on the task of finding architectural forms of dome systems through cutting axisymmetric ones, an "antiderivative" symmetrical structure for a pontoon-cable bridge is proposed, which will meet the specified characteristics. Based on the study of existing cable and tensegrity structures, three alternative architectural forms for the pontoon-cable bridge were developed. Originality. Analysis of existing sources, including constructed and designed tensegrity bridges and other structures, was conducted. A summary about the feasibility and usefulness of this approach for a previously proposed pontoon-cable bridge has been made. It was concluded that, in the future, this bridge can be considered from the tensegrity point of view, provided that the introduction of some tolerances or auxiliary elements were made. Practical value. For the existing structure of the pontoon-cable bridge, after considering it from the tensegrity and other cable structures’ point of view, alternative forms are proposed that may have additional advantages for specific design or construction conditions.

Chitin Deacetylase Homologous Gene cda Contributes to Development and Aflatoxin Synthesis in Aspergillus flavus

The fungal cell wall serves as the primary interface between fungi and their external environment, providing protection and facilitating interactions with the surroundings. Chitin is a vital structural element in fungal cell wall. Chitin deacetylase (CDA) can transform chitin into chitosan through deacetylation, providing various biological functions across fungal species. Although this modification is widespread in fungi, the biological functions of CDA enzymes in Aspergillus flavus remain largely unexplored. In this study, we aimed to investigate the biofunctions of the CDA family in A. flavus. The A. flavus genome contains six annotated putative chitin deacetylases. We constructed knockout strains targeting each member of the CDA family, including Δcda1, Δcda2, Δcda3, Δcda4, Δcda5, and Δcda6. Functional analyses revealed that the deletion of CDA family members neither significantly affects the chitin content nor exhibits the expected chitin deacetylation function in A. flavus. However, the Δcda6 strain displayed distinct phenotypic characteristics compared to the wild-type (WT), including an increased conidia count, decreased mycelium production, heightened aflatoxin production, and impaired seed colonization. Subcellular localization experiments indicated the cellular localization of CDA6 protein within the cell wall of A. flavus filaments. Moreover, our findings highlight the significance of the CBD1 and CBD2 structural domains in mediating the functional role of the CDA6 protein. Overall, we analyzed the gene functions of CDA family in A. flavus, which contribute to a deeper understanding of the mechanisms underlying aflatoxin contamination and lay the groundwork for potential biocontrol strategies targeting A. flavus.