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Artykuły w czasopismach na temat "Scaffold based models"
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Massai, Diana, Francesco Pennella, Piergiorgio Gentile, Diego Gallo, Gianluca Ciardelli, Cristina Bignardi, Alberto Audenino i Umberto Morbiducci. "Image-Based Three-Dimensional Analysis to Characterize the Texture of Porous Scaffolds". BioMed Research International 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/161437.
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The aim of the present study is to characterize the microstructure of composite scaffolds for bone tissue regeneration containing different ratios of chitosan/gelatin blend and bioactive glasses. Starting from realistic 3D models of the scaffolds reconstructed from micro-CT images, the level of heterogeneity of scaffold architecture is evaluated performing a lacunarity analysis. The results demonstrate that the presence of the bioactive glass component affects not only macroscopic features such as porosity, but mainly scaffold microarchitecture giving rise to structural heterogeneity, which could have an impact on the local cell-scaffold interaction and scaffold performances. The adopted approach allows to investigate the scale-dependent pore distribution within the scaffold and the related structural heterogeneity features, providing a comprehensive characterization of the scaffold texture.
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Gao, Han Jun, Hao Yuan, Jian Qiang Xia, Hong Wei Li i Yi Du Zhang. "Design and Simulation of Ti6Al4V Cartilage Scaffold Based on Additive Manufacturing Technology". Materials Science Forum 1032 (maj 2021): 114–19. http://dx.doi.org/10.4028/www.scientific.net/msf.1032.114.
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The combination of additive manufacturing technology and cartilage tissue scaffold construction provides a new way for clinical treatment of cartilage injury. The high priority of the cartilage scaffold is closely related to the excellent biomechanical properties, fatigue life and medical performance. In this paper, three kinds of cartilage scaffolds are designed, and three-dimensional parametric geometric and numerical simulation models are established. Based on the simulation analysis and comparison of the three kinds of scaffolds, a scaffold model is finally determined. The porosity reaches 87.38%, the equivalent elastic modulus is 9.64Gpa, and it has permanent fatigue life in service environment. It concluded that the designed Ti6Al4V titanium alloy scaffold is suitable for cartilage transplantation.
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Farina, Erica, Dario Gastaldi, Francesco Baino, Enrica Vernè, Jonathan Massera, Gissur Orlygsson i Pasquale Vena. "Micro computed tomography based finite element models for elastic and strength properties of 3D printed glass scaffolds". Acta Mechanica Sinica 37, nr 2 (luty 2021): 292–306. http://dx.doi.org/10.1007/s10409-021-01065-3.
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Abstract In this study, the mechanical properties of glass scaffolds manufactured by robocasting are investigated through micro computed tomography ($$\mu -CT$$ μ - C T ) based finite element modeling. The scaffolds are obtained by printing fibers along two perpendicular directions on parallel layers with a $$90^\circ $$ 90 ∘ tilting between two adjacent layers. A parametric study is first presented with the purpose to assess the effect of the major design parameters on the elastic and strength properties of the scaffold; the mechanical properties of the 3D printed scaffolds are eventually estimated by using the $$\mu -CT$$ μ - C T data with the aim of assessing the effect of defects on the final geometry which are intrinsic in the manufacturing process. The macroscopic elastic modulus and strength of the scaffold are determined by simulating a uniaxial compressive test along the direction which is perpendicular to the layers of the printed fibers. An iterative approach has been used in order to determine the scaffold strength. A partial validation of the computational model has been obtained through comparison of the computed results with experimental values presented in [10] on a ceramic scaffold having the same geometry. All the results have been presented as non-dimensional values. The finite element analyses have shown which of the selected design parameters have the major effect on the stiffness and strength, being the porosity and fiber shifting between adjacent layers the most important ones. The analyses carried out on the basis of the $$\mu -CT$$ μ - C T data have shown elastic modulus and strength which are consistent with that found on ideal geometry at similar macroscopic porosity. Graphic Abstract In this work, elastic and strength properties of glass-ceramic Bone Tissue Engineering scaffolds manufactured by robocasting are investigated through micro-CT based finite element models. An incremental simulation using a multi-grid finite element solver has been implemented to perform a parametric study on the effect of the major geometrical parameters of the scaffold design as well as the effect. Eventually, the effect of the geometrical imperfections deriving from the 3D printing process has been investigated by means of micro-CT image-based models. The porosity and the shifting between adjacent layers play the dominant role in determing elasticity and strength of the scaffolds. The elastic and strength properties of 3D-printed real scaffold were assessed to be consistent those obtained from the idealized geometric models, at least for the subdomain used in this study.
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Damerau, Alexandra, Frank Buttgereit i Timo Gaber. "Optimization of a Tricalcium Phosphate-Based Bone Model Using Cell-Sheet Technology to Simulate Bone Disorders". Processes 10, nr 3 (11.03.2022): 550. http://dx.doi.org/10.3390/pr10030550.
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Bone diseases such as osteoporosis, delayed or impaired bone healing, and osteoarthritis still represent a social, financial, and personal burden for affected patients and society. Fully humanized in vitro 3D models of cancellous bone tissue are needed to develop new treatment strategies and meet patient-specific needs. Here, we demonstrate a successful cell-sheet-based process for optimized mesenchymal stromal cell (MSC) seeding on a β-tricalcium phosphate (TCP) scaffold to generate 3D models of cancellous bone tissue. Therefore, we seeded MSCs onto the β-TCP scaffold, induced osteogenic differentiation, and wrapped a single osteogenically induced MSC sheet around the pre-seeded scaffold. Comparing the wrapped with an unwrapped scaffold, we did not detect any differences in cell viability and structural integrity but a higher cell seeding rate with osteoid-like granular structures, an indicator of enhanced calcification. Finally, gene expression analysis showed a reduction in chondrogenic and adipogenic markers, but an increase in osteogenic markers in MSCs seeded on wrapped scaffolds. We conclude from these data that additional wrapping of pre-seeded scaffolds will provide a local niche that enhances osteogenic differentiation while repressing chondrogenic and adipogenic differentiation. This approach will eventually lead to optimized preclinical in vitro 3D models of cancellous bone tissue to develop new treatment strategies.
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Valdoz, Jonard Corpuz, Benjamin C. Johnson, Dallin J. Jacobs, Nicholas A. Franks, Ethan L. Dodson, Cecilia Sanders, Collin G. Cribbs i Pam M. Van Ry. "The ECM: To Scaffold, or Not to Scaffold, That Is the Question". International Journal of Molecular Sciences 22, nr 23 (24.11.2021): 12690. http://dx.doi.org/10.3390/ijms222312690.
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The extracellular matrix (ECM) has pleiotropic effects, ranging from cell adhesion to cell survival. In tissue engineering, the use of ECM and ECM-like scaffolds has separated the field into two distinct areas—scaffold-based and scaffold-free. Scaffold-free techniques are used in creating reproducible cell aggregates which have massive potential for high-throughput, reproducible drug screening and disease modeling. Though, the lack of ECM prevents certain cells from surviving and proliferating. Thus, tissue engineers use scaffolds to mimic the native ECM and produce organotypic models which show more reliability in disease modeling. However, scaffold-based techniques come at a trade-off of reproducibility and throughput. To bridge the tissue engineering dichotomy, we posit that finding novel ways to incorporate the ECM in scaffold-free cultures can synergize these two disparate techniques.
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Rojas-Rojas, Laura, María Laura Espinoza-Álvarez, Silvia Castro-Piedra, Andrea Ulloa-Fernández, Walter Vargas-Segura i Teodolito Guillén-Girón. "Muscle-like Scaffolds for Biomechanical Stimulation in a Custom-Built Bioreactor". Polymers 14, nr 24 (11.12.2022): 5427. http://dx.doi.org/10.3390/polym14245427.
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Tissue engineering aims to develop in-vitro substitutes of native tissues. One approach of tissue engineering relies on using bioreactors combined with biomimetic scaffolds to produce study models or in-vitro substitutes. Bioreactors provide control over environmental parameters, place and hold a scaffold under desired characteristics, and apply mechanical stimulation to scaffolds. Polymers are often used for fabricating tissue-engineering scaffolds. In this study, polycaprolactone (PCL) collagen-coated microfilament scaffolds were cell-seeded with C2C12 myoblasts; then, these were grown inside a custom-built bioreactor. Cell attachment and proliferation on the scaffolds were investigated. A loading pattern was used for mechanical stimulation of the cell-seeded scaffolds. Results showed that the microfilaments provided a suitable scaffold for myoblast anchorage and that the custom-built bioreactor provided a qualified environment for the survival of the myoblasts on the polymeric scaffold. This PCL-based microfilament scaffold located inside the bioreactor proved to be a promising structure for the study of skeletal muscle models and can be used for mechanical stimulation studies in tissue engineering applications.
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Basri, Hasan, Jimmy Deswidawansyah Nasution, Ardiyansyah Syahrom, Mohd Ayub Sulong, Amir Putra Md. Saad, Akbar Teguh Prakoso i Faisal Aminin. "The effect to flow rate characteristic on biodegradation of bone scaffold". Malaysian Journal of Fundamental and Applied Sciences 13, nr 4-2 (17.12.2017): 546–52. http://dx.doi.org/10.11113/mjfas.v13n4-2.843.
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This paper proposes an improved modeling approach for bone scaffolds biodegradation. In this study, the numerical analysis procedure and computer-based simulation were performed for the bone scaffolds with varying porosities in determining the wall shear stresses and the permeabilities along with their influences on the scaffolds biodegradation process while the bio-fluids flow through within followed with the change in the flow rates. Based on the experimental study by immersion testing from 0 to 72 hours of the time period, the specimens with different morphologies of the commercial bone scaffolds were collected into three groups samples of 30%, 41%, and 55% porosities. As the representative of the cancellous bone morphology, the morphological degradation was observed by using 3-D CAD scaffold models based on microcomputed tomography images. By applying the boundary conditions to the computational fluid dynamics (CFD) and the fluid-structure interaction (FSI) models, the wall shear stresses within the scaffolds due to fluid flow rates variation had been simulated and determined before and after degradation. The increase of fluid flow rates tends to raise the pressure drop for scaffold models with porosities lower than 50% before degradation. As the porosities increases, the pressure drop decreases with an increase in permeability within the scaffold. The flow rates have significant effects on scaffolds with higher pressure drops by introducing the wall shear stresses with the highest values and lower permeability. These findings indicate the importance of using accurate computational models to estimate shear stress and determine experimental conditions in perfusion bioreactors for tissue engineering more accurate results will be achieved to indicate the natural distributions of fluid flow velocity, wall shear stress, and pressure.
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Acevedo, Cristian A., Yusser Olguín, Nicole Orellana, Elizabeth Sánchez, Marzena Pepczynska i Javier Enrione. "Anatase Incorporation to Bioactive Scaffolds Based on Salmon Gelatin and Its Effects on Muscle Cell Growth". Polymers 12, nr 9 (28.08.2020): 1943. http://dx.doi.org/10.3390/polym12091943.
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The development of new polymer scaffolds is essential for tissue engineering and for culturing cells. The use of non-mammalian bioactive components to formulate these materials is an emerging field. In our previous work, a scaffold based on salmon gelatin was developed and tested in animal models to regenerate tissues effectively and safely. Here, the incorporation of anatase nanoparticles into this scaffold was formulated, studying the new composite structure by scanning electron microscopy, differential scanning calorimetry and dynamic mechanical analysis. The incorporation of anatase nanoparticles modified the scaffold microstructure by increasing the pore size from 208 to 239 µm and significantly changing the pore shape. The glass transition temperature changed from 46.9 to 55.8 °C, and an increase in the elastic modulus from 79.5 to 537.8 kPa was observed. The biocompatibility of the scaffolds was tested using C2C12 myoblasts, modulating their attachment and growth. The anatase nanoparticles modified the stiffness of the material, making it possible to increase the growth of myoblasts cultured onto scaffolds, which envisions their use in muscle tissue engineering.
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Peng, Liqing, Bin Zhang, Xujiang Luo, Bo Huang, Jian Zhou, Shuangpeng Jiang, Weimin Guo i in. "Small Ruminant Models for Articular Cartilage Regeneration by Scaffold-Based Tissue Engineering". Stem Cells International 2021 (6.12.2021): 1–14. http://dx.doi.org/10.1155/2021/5590479.
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Animal models play an important role in preclinical studies, especially in tissue engineering scaffolds for cartilage repair, which require large animal models to verify the safety and effectiveness for clinical use. The small ruminant models are most widely used in this field than other large animals because they are cost-effective, easy to raise, not to mention the fact that the aforementioned animal presents similar anatomical features to that of humans. This review discusses the experimental study of tissue engineering scaffolds for knee articular cartilage regeneration in small ruminant models. Firstly, the selection of these scaffold materials and the preparation process in vitro that have been already used in vivo are briefly reviewed. Moreover, the major factors influencing the rational design and the implementation as well as advantages and limitations of small ruminants are also demonstrated. As regards methodology, this paper applies principles and methods followed by most researchers in the process of experimental design and operation of this kind. By summarizing and comparing different therapeutic concepts, this paper offers suggestions aiming to increase the effectiveness of preclinical research using small ruminant models and improve the process of developing corresponding therapies.
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Zhou, Yang, Gillian Pereira, Yuanzhang Tang, Matthew James i Miqin Zhang. "3D Porous Scaffold-Based High-Throughput Platform for Cancer Drug Screening". Pharmaceutics 15, nr 6 (9.06.2023): 1691. http://dx.doi.org/10.3390/pharmaceutics15061691.
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Natural polymer-based porous scaffolds have been investigated to serve as three-dimensional (3D) tumor models for drug screening owing to their structural properties with better resemblance to human tumor microenvironments than two-dimensional (2D) cell cultures. In this study, a 3D chitosan–hyaluronic acid (CHA) composite porous scaffold with tunable pore size (60, 120 and 180 µm) was produced by freeze-drying and fabricated into a 96-array platform for high-throughput screening (HTS) of cancer therapeutics. We adopted a self-designed rapid dispensing system to handle the highly viscous CHA polymer mixture and achieved a fast and cost-effective large-batch production of the 3D HTS platform. In addition, the adjustable pore size of the scaffold can accommodate cancer cells from different sources to better mimic the in vivo malignancy. Three human glioblastoma multiforme (GBM) cell lines were tested on the scaffolds to reveal the influence of pore size on cell growth kinetics, tumor spheroid morphology, gene expression and dose-dependent drug response. Our results showed that the three GBM cell lines showed different trends of drug resistance on CHA scaffolds of varying pore size, which reflects the intertumoral heterogeneity across patients in clinical practice. Our results also demonstrated the necessity to have a tunable 3D porous scaffold for adapting the heterogeneous tumor to generate the optimal HTS outcomes. It was also found that CHA scaffolds can produce a uniform cellular response (CV < 0.15) and a wide drug screening window (Z′ > 0.5) on par with commercialized tissue culture plates, and therefore, can serve as a qualified HTS platform. This CHA scaffold-based HTS platform may provide an improved alternative to traditional 2D-cell-based HTS for future cancer study and novel drug discovery.
Rozprawy doktorskie na temat "Scaffold based models"
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Loira, Nicolas. "Scaffold-based Reconstruction Method for Genome-Scale Metabolic Models". Phd thesis, Université Sciences et Technologies - Bordeaux I, 2012. http://tel.archives-ouvertes.fr/tel-00678991.
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La compréhension des organismes vivant a été une quête pendant longtemps. Depuis les premiers progrès des derniers siècles, nous sommes arrivés jusqu'au point où des quantités massives de données et d'information sont constamment générées. Bien que, jusqu'au present la plupart du travail a été concentré sur la génération d'un catalogue d'éléments biologiques, ce n'est pas que récemment qu'un effort coordonné pour dé- couvrir les réseaux de relations entre ces parties a'été constaté. Nous sommes intereses à comprendre non pas seulement ces réseaux, mais aussi la façon dont, à partir de ses connexions, émergent des fonctions biologiques. Ce travail se concentre sur la découverte, la modélisation et l'exploitation d'un de ces réseaux : le métabolisme. Un réseau métabolique est un ensemble des réac- tions biochimiques interconnectées qui se produisent à l'intérieur, ou dans les limites d'une cellule vivante. Une nouvelle méthode de découverte, ou de reconstruction des réseaux métaboliques est proposée dans ce travail, avec une emphase particulière sur les organismes eucaryotes. Cette nouvelle méthode est divisée en deux parties : une nouvelle approche pour la modélisation de la reconstruction basée sur l'instanciation des éléments d'un modèle squelette existant, et une nouvelle méthode de réécriture d'association des gènes. Cette méthode en deux parties permet des reconstructions qui vont au-delà de la capacité des méthodes de l'état de l'art, permettant la reconstruction de modèles métaboliques des organismes eucaryotes, et fournissant une relation détaillée entre ses réactions et ses gènes, des connaissances cruciales pour des applications biotechnologies. Les méthodes de reconstruction développées dans ce travail, ont été complétées par un workflow itératif d'édition, de vérification et d'amélioration du modèle. Ce workflow a été implémenté dans un logiciel, appelé Pathtastic. Comme une étude de cas de la méthode développée et implémentée dans le pré- sent travail, le réseau métabolique de la levure oléagineuse Yarrowia lipolytica, connu comme contaminant alimentaire et utilisé pour la biorestauration et comme usine cellulaire, a été reconstruit. Une version préliminaire du modèle a été générée avec Pathtastic, laquelle a été améliorée par curation manuelle, à travers d'un travail avec des spécialistes dans le domaine de cette espèce. Les données expérimentales, obtenues à partir de la littérature, ont été utilisées pour évaluer la qualité du modèle produit. La méthode de reconstruction chez les eucaryotes, et le modèle reconstruit de Y. lipolytica peuvent être utiles pour les communautés scientifiques respectives, le premier comme un pas vers une meilleure reconstruction automatique des réseaux métaboliques, et le deuxième comme un soutien à la recherche, un outil pour des applications biotechnologiques et comme un étalon-or pour les reconstructions futures.
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Loira, Nicolas. "Scaffold-based reconstruction method of genome-scale metabolic models". Thesis, Bordeaux 1, 2012. http://www.theses.fr/2012BOR14484/document.
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La compréhension des organismes vivant a été une quête pendant longtemps. Depuisles premiers progrès des derniers siècles, nous sommes arrivés jusqu’au point où desquantités massives de données et d’information sont constamment générées. Bien que,jusqu’au présent la plupart du travail a été concentré sur la génération d’un catalogued’éléments biologiques, ce n’est pas que récemment qu’un effort coordonné pour découvrirles réseaux de relations entre ces parties a été constaté. Nous nous sommes intéressésà comprendre non pas seulement ces réseaux, mais aussi la façon dont, à partir de sesconnexions, émergent des fonctions biologiques.Ce travail se concentre sur la modélisation et l’exploitation d’un de ces réseaux :le métabolisme. Un réseau métabolique est un ensemble des réactions biochimiquesinterconnectées qui se produisent à l’intérieur, ou dans les proximité d’une cellulevivante. Une nouvelle méthode de découverte, ou de reconstruction des réseaux métaboliquesest proposée dans ce travail, avec une emphase particulière sur les organismeseucaryotes.Cette nouvelle méthode est divisée en deux parties : une nouvelle approche pour lamodélisation de la reconstruction basée sur l’instanciation des éléments d’un modèlesquelette existant, et une nouvelle méthode de réécriture d’association des gènes. Cetteméthode en deux parties permet des reconstructions qui vont au-delà de la capacitédes méthodes de l’état de l’art, permettant la reconstruction de modèles métaboliquesdes organismes eucaryotes, et fournissant une relation détaillée entre ses réactions etses gènes, des connaissances cruciales pour des applications biotechnologiques.Les méthodes de reconstruction développées dans ce travail, ont été complétéespar un workflow itératif d’édition, de vérification et d’amélioration du modèle. Ceworkflow a été implémenté dans un logiciel, appelé Pathtastic.Comme une étude de cas de la méthode développée et implémentée dans le présenttravail, le réseau métabolique de la levure oléagineuse Yarrowia lipolytica, connucomme contaminant alimentaire et utilisé pour la biorestauration et comme usinecellulaire, a été reconstruit. Une version préliminaire du modèle a été générée avecPathtastic, laquelle a été améliorée par curation manuelle, à travers d’un travail avecdes spécialistes dans le domaine de cette espèce. Les données expérimentales, obtenuesà partir de la littérature, ont été utilisées pour évaluer la qualité du modèle produit.La méthode de reconstruction chez les eucaryotes, et le modèle reconstruit deY. lipolytica peuvent être utiles pour les communautés scientifiques respectives, lepremier comme un pas vers une meilleure reconstruction automatique des réseauxmétaboliques, et le deuxième comme un soutien à la recherche, un outil pour desapplications biotechnologiques et comme un étalon-or pour les reconstructions futuresUnderstanding living organisms has been a quest for a long time. Since the advancesof the last centuries, we have arrived to a point where massive quantities of data andinformation are constantly generated. Even though most of the work so far has focusedon generating a parts catalog of biological elements, only recently have we seena coordinated effort to discover the networks of relationships between those parts. Notonly are we trying to understand these networks, but also the way in which, from theirconnections, emerge biological functions.This work focuses on the modeling and exploitation of one of those networks:metabolism. A metabolic network is a net of interconnected biochemical reactionsthat occur inside, or in the proximity of, a living cell. A new method of discovery, orreconstruction, of metabolic networks is proposed in this work, with special emphasison eukaryote organisms.This new method is divided in two parts: a novel approach to reconstruct metabolicmodels, based on instantiation of elements of an existing scaffold model, and a novelmethod of assigning gene associations to reactions. This two-parts method allows reconstructionsthat are beyond the capacity of the state-of-the-art methods, enablingthe reconstruction of metabolic models of eukaryotes, and providing a detailed relationshipbetween its reactions and genes, knowledge that is crucial for biotechnologicalapplications.The reconstruction methods developed for the present work were complementedwith an iterative workflow of model edition, verification and improvement. This workflowwas implemented as a software package, called Pathtastic.As a case study of the method developed and implemented in the present work,we reconstructed the metabolic network of the oleaginous yeast Yarrowia lipolytica,known as food contaminant and used for bioremediation and as a cell factory. A draftversion of the model was generated using Pathtastic, and further improved by manualcuration, working closely with specialists in that species. Experimental data, obtainedfrom the literature, were used to assess the quality of the produced model.Both, the method of reconstruction in eukaryotes, and the reconstructed model ofY. lipolytica can be useful for their respective research communities, the former as astep towards better automatic reconstructions of metabolic networks, and the latteras a support for research, a tool in biotechnological applications and a gold standardfor future reconstructions
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Patel, Kunal. "Stiffness Gradient Scaffolds as an In Vitro Model for Stem Cell Based Cardiac Cell Therapy". University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1386725736.
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Yong, Mostyn R. "Characterisation of Polycaprolatone-Based Scaffold Plus Recombinant Human Morphogenetic Protein - 2 (RHBMP-2) in an Ovine Thoracic Spine Model". Thesis, Queensland University of Technology, 2013. https://eprints.qut.edu.au/64093/1/Mostyn_Yong_Thesis.pdf.
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This thesis represents a step forward in the development of a pre-clinical model investigating a suitable substitute for host bone for use in human spinal fusion.
By way of an animal model, it examines the biological performance of a novel bone graft substitute comprised of a combination of a custom-designed biodegradable material and biologics.
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Whitney, G. Adam. "Characterization of the Frictional-Shear Damage Properties of Scaffold-Free Engineered Cartilage and Reduction of Damage Susceptibility by Upregulation of Collagen Content". Case Western Reserve University School of Graduate Studies / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=case1417470427.
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Maghdouri-White, Yas. "Mammary Epithelial Cells Cultured onto Non-Woven Nanofiber Electrospun Silk-Based Biomaterials to Engineer Breast Tissue Models". VCU Scholars Compass, 2014. http://scholarscompass.vcu.edu/etd/3358.
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Breast cancer is one of the most common types of cancer affecting women in the world today. To better understand breast cancer initiation and progression modeling biological tissue under physiological conditions is essential. Indeed, breast cancer involves complex interactions between mammary epithelial cells and the stroma, both extracellular matrix (ECM) and cells including adipocytes (fat tissue) and fibroblasts (connective tissue). Therefore, the engineering of in vitro three-dimensional (3D) systems of breast tissues allows a deeper understanding of the complex cell-cell and cell-ECM interactions involved during breast tissue development and cancer initiation and progression. Furthermore, such 3D systems may provide a viable alternative to investigate new drug or drug regimen and to model and monitor concurrent cellular processes during tumor growth and invasion. The development of suitable 3D in vitro models relies on the ability to mimic the microenvironment, the structure, and the functions of the breast tissue. Different approaches to develop a novel 3D breast model have been investigated. Most models use gel scaffolds, including Matrigel® and collagen to generate breast tissue-like structures. However, the physicochemical, mechanical, and geometrical properties of these scaffolds only partially meet the mechanical, physical, and chemical parameters of the breast tissue matrix. In the present studies, we investigated the overall hypothesis that electrospun SF-derived scaffolds promote mammary cell growth and the formation of mammary-like structures depending on the composition and/or coating of the scaffolds with ECM proteins. Through an extensive literature search (1) the importance of 3D modeling of tissues and organs in vivo, (2) 3D modeling of the mammary tissue and currently available models, (3) the properties and applications of SF in tissue modeling and regeneration were reviewed (Chapter 1). Our studies provide evidence of the effects of various concentrations (Chapter 2) of SF along with different electrospinning techniques (Chapter 3) on the structure of electrospun scaffolds and whether those scaffolds provide suitable microenvironments for mammary epithelial cells as determined by MCF10A cell attachment, viability, and structure formation. Further, we investigated the effects of the key ECM proteins collagen I (Chapter 4) and laminin (Chapter 5) used to blend or coat, respectively, SF scaffolds on the attachment, viability and structure formation of mammary epithelial cells. Our studies first highlight the mechanical and physical properties of the different SF-derived scaffolds through various SF concentrations and electrospinning techniques. Second, the biocompatibility of these SF electrospun scaffolds was defined based on MCF10A cell survival and adhesion. Third, our data indicate that scaffolds derived from blended and/or coated SF with collagen I also promoted human mammary cell survival and adhesion. Lastly, our observations suggest that on laminin-coated SF scaffolds MCF10A mammary cells, in the presence of lactogenic hormones, differentiated forming acinus-like structures. Overall, these studies provide evidence that SF electrospun scaffolds closely mimic the structure of the ECM fibers and allow many advantages such as; physical and chemical modification of the microenvironment by varying electrospinning parameters and addition of various proteins, hormones, and growth factors, respectively. Further, coating these SF scaffolds with essential ECM proteins, in particular laminin, promote cell-ECM interactions necessary for cell differentiation and formation of growth-arrested structures, through providing cell integrin binding sites and appropriate chemical cues.
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Piccirillo, Germano Pasquale. "Development of new in vitro models based on the use of electrospun scaffolds and their imaging by multiphoton microscopy coupled with fluorescence lifetime imaging microscopy". Doctoral thesis, Universita degli studi di Salerno, 2018. http://hdl.handle.net/10556/3021.
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2016 - 2017In this thesis, new possible applications of electrospun scaffolds are presented. Besides, the interaction of human dermal fibroblasts (HDFs) with the materials has been investigated using multiphoton microscopy (MPM) coupled with fluorescence lifetime imaging microscopy (FLIM), using a non-invasive, marker-free approach. In the first part of the thesis, pure poly-L-lactide (PLA) scaffolds were obtained and characterized as delivery systems for Diclofenac sodium salt (DCF) and a synthetically obtained prodrug of it for the treatment of actinic keratosis. The Diclofenac prodrug was obtained via solid phase peptide synthesis using a versatile, clean, high yielding procedure. Besides, the drug encapsulation and its release from the scaffold could be imaged using MPM. Moreover, when working with the unmodified DCF we were able to control the release profile by adding small amounts of dimethyl sulfoxide. The DCF-loaded scaffold was used as a delivery system to induce in vitro cell death in HDFs. The target cells were imaged using MPM coupled with FLIM, using a non-invasive, marker-free in vitro model to investigate drug effects. In the last part of the thesis, we produced and characterized different hybrid gelatin/PLA scaffolds. In this case, the goal was to obtain well-blended scaffolds with tunable properties, such as porosity, hydrophobicity and wettability... [edited by Author]
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Tetteh, Gifty. "Polyurethane-based scaffolds for bone tissue engineering : the role of hydroxyapatite particles, solvent combinations, electrospun fibre orientations, in vivo & in vitro characterisation, and particulate leached foams for creating 3-D bone models". Thesis, University of Sheffield, 2016. http://etheses.whiterose.ac.uk/16015/.
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While small bone defects heal spontaneously, critical size defects may exceed the body’s regenerative capabilities, and require the use of bone substitutes and implants. To date, in vitro and in vivo testing of implants remains the gold standard for rigorous mechanical stability and biological safety checks. Current 2D in vitro testing is limited by a lack of dynamic environment and an inability to investigate mechanical strength of the attachment between the bone-matrix and implant surface. 3D in vivo tests are also limited by differences in the behaviour and structure of human and animal cells, high costs and difficulty of replicating human ageing effects. The aim of this thesis is to develop biocompatible and osteoconductive polyurethane-based scaffolds with optimal mechanical and biological properties that can be used as 3D in vitro bone models for bone regeneration and implant testing. 17 Plain-PU and PU-HA scaffolds were fabricated from three different medical grade polyether-urethanes, namely, Z1A1, Z3A1 and Z9A1. The polymer’s ability to dissolve in graded concentrations of DMF/THF solvents was assessed as part of this study. Composite scaffolds containing nano or micro HA particles were fabricated in a ratio of 3 PU: 1 HA by doping PU solutions with HA particles. Electrospinning, freeze drying, freeze extraction and particulate leaching were the main fabrication techniques explored for creating scaffolds. Electrospun scaffolds with non-aligned fibres were spun at 300 rpm whilst those with aligned fibres were spun at 1300 rpm. Particulate leaching using NaCl particles optimized 3 novel fabrication protocols namely, the layer-by-layer, homogenized or physical-mixing techniques for creating highly porous PU-based constructs. Investigation of non-aligned electrospun scaffolds showed that the choice of solvents, on their own or in combination, strongly influences the final properties of solution, hence the fibre morphology of scaffolds. Reducing the amount of DMF contained in the solution, increased fibre diameter, eliminated beads in fibres and led to scaffolds with a more uniform morphology. Moreover, reducing the DMF solvent content led to lower tensile properties of electrospun scaffolds, whilst incorporation of nano and micro HA particles reinforced the mechanical properties of both aligned and non-aligned electrospun composites. RAMAN and FTIR spectroscopy confirmed the presence of HA in all composites. Xylenol orange staining showed that composite mHA scaffolds supported a higher percentage of mineral area coverage compared to plain-PU scaffolds. SHG imaging identified that collagen deposition appeared to be guided by the alignment of the scaffold fibres in the matrix deposited near to the fibres, but changed orientation with an increase in distance from the originally deposited layers. Layer-by-Layer particulate leached scaffolds made from all the three types of PU had a highly porous 3D structure. 3:1 PU:nano-HA composites had the highest Young’s Modulus and yield strength in the Layer-by-Layer group and there was no significant difference between the mechanical properties of 3:1 micro-HA composites and 2:1 micro-HA composites. A novel physical mixing fabrication protocol shortened fabrication time by about 90% and was used to mass produce particulate leached scaffolds in a shorter period of time. Physically mixed particulate leached scaffolds had an interesting and contrasting mechanical profile compared to previously fabricated scaffolds. Physically mixed PU scaffolds without HA had the highest mechanical properties in this group and the inclusion of neither nano, micro nor combined micro and nano-HA particles enhanced their mechanical properties. Similar to the Layer-by-Layer particulate leached scaffolds, the inclusion of HA particles in physically mixed PU-only scaffolds did not support a higher cell viability. Osteoid bone formation was present in only nHA composites by D7 of the in vivo studies, but present in all scaffolds after D45. Collagenous matrix deposition increased over the 56 day period in all scaffold types, however, this increase was more pronounced in PU-only scaffolds. Finally, mimicking push-out and pull-out tests by inserting titanium screws into particulate leached scaffolds, showed that inserting the screws during cell seeding is a better method than inserting them after a D28 culture period. PU-based scaffolds that serve as a novel biomimetic in vitro 3D bone model for testing of small orthopaedic implants have been developed.
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Ramalho, Pedro Alves Douteiro Cranfield. "Preliminary design of an Achilles tendon scaffold based on a simple model approach". Master's thesis, 2018. https://repositorio-aberto.up.pt/handle/10216/116468.
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Ramalho, Pedro Alves Douteiro Cranfield. "Preliminary design of an Achilles tendon scaffold based on a simple model approach". Dissertação, 2018. https://repositorio-aberto.up.pt/handle/10216/116468.
Pełny tekst źródłaKsiążki na temat "Scaffold based models"
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Duncan, Anthony, i Michel Janssen. Constructing Quantum Mechanics. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780198845478.001.0001.
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This is the first of two volumes on the genesis of quantum mechanics. It covers the key developments in the period 1900–1923 that provided the scaffold on which the arch of modern quantum mechanics was built in the period 1923–1927 (covered in the second volume). After tracing the early contributions by Planck, Einstein, and Bohr to the theories of black‐body radiation, specific heats, and spectroscopy, all showing the need for drastic changes to the physics of their day, the book tackles the efforts by Sommerfeld and others to provide a new theory, now known as the old quantum theory. After some striking initial successes (explaining the fine structure of hydrogen, X‐ray spectra, and the Stark effect), the old quantum theory ran into serious difficulties (failing to provide consistent models for helium and the Zeeman effect) and eventually gave way to matrix and wave mechanics. Constructing Quantum Mechanics is based on the best and latest scholarship in the field, to which the authors have made significant contributions themselves. It breaks new ground, especially in its treatment of the work of Sommerfeld and his associates, but also offers new perspectives on classic papers by Planck, Einstein, and Bohr. Throughout the book, the authors provide detailed reconstructions (at the level of an upper‐level undergraduate physics course) of the cental arguments and derivations of the physicists involved. All in all, Constructing Quantum Mechanics promises to take the place of older books as the standard source on the genesis of quantum mechanics.
Części książek na temat "Scaffold based models"
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Murphy, Catherine, Ciara Gallagher i Olga Piskareva. "Evaluation of miRNA Expression in 3D In Vitro Scaffold-Based Cancer Models". W Methods in Molecular Biology, 211–24. New York, NY: Springer US, 2022. http://dx.doi.org/10.1007/978-1-0716-2823-2_15.
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Gupta, Priyanka, i Eirini G. Velliou. "A Step-by-Step Methodological Guide for Developing Zonal Multicellular Scaffold-Based Pancreatic Cancer Models". W Methods in Molecular Biology, 221–29. New York, NY: Springer US, 2023. http://dx.doi.org/10.1007/978-1-0716-3056-3_13.
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Andrei, Oana, i Muffy Calder. "Trend-Based Analysis of a Population Model of the AKAP Scaffold Protein". W Lecture Notes in Computer Science, 1–25. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-35524-0_1.
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Fink, Maximilian C., Victoria Reitmeier, Matthias Siebeck, Frank Fischer i Martin R. Fischer. "Live and Video Simulations of Medical History-Taking: Theoretical Background, Design, Development, and Validation of a Learning Environment". W Learning to Diagnose with Simulations, 109–22. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-89147-3_9.
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AbstractHistory-taking is an essential diagnostic situation and has long been an important objective of medical education in European countries and beyond. Thus, the research project presented here investigates facilitating diagnostic competences in live and video history-taking simulations. In this chapter, the theoretical background and the design, development, and validation process of the learning environment for this research project are described. In the first section, an overview of history-taking models is provided, the concept of diagnostic competences for history-taking is specified, and a summary of research on simulation-based learning and assessment of history-taking is given. The second section reports on the creation of knowledge tests and the live and video simulations. In the third section, results from a pilot study and an expert workshop are disclosed and findings from a validation study are provided. These findings indicate that the created simulations and knowledge tests measure separate but related aspects of diagnostic competences reliably and validly and may be used for assessment. In the final section, a summary is provided and future questions for research are presented with a focus on the adaptivity of scaffolds and simulation-based learning from atypical cases.
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Brouwer, Jasperina, i Carlos A. de Matos Fernandes. "Using Stochastic Actor-Oriented Models to Explain Collaboration Intentionality as a Prerequisite for Peer Feedback and Learning in Networks". W The Power of Peer Learning, 103–20. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-29411-2_5.
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AbstractPeer feedback and collaboration intentionality (CI) are key prerequisites to advance in higher education. For learning, it is crucial that peers do not merely interact, but that students are willing to function as scaffolds by sharing their knowledge from different perspectives and asking each other for academic support. Peer feedback can only take place within a collaborative learning approach and when students are willing to initiate feedback relationships with their peers. Therefore, we analyze peer feedback networks (in terms of academic help and advice-seeking) and CI as an individual characteristic using an advanced statistical tool, namely stochastic actor-oriented models (SAOMs). In SAOMs, we control for selection and influence mechanisms. Selection comprises instances when feedback relations can be initiated based on CI, while influence builds upon existing feedback relations in affecting CI. One important selection mechanism is homophily, which means that individuals prefer to initiate a connection with someone else based on similarity in characteristics, attitudes, or behavior. In this chapter, we introduce this statistical technique within the higher education context and the added value for feedback research in education. We illustrate the SAOM methodology using two-wave peer feedback networks and CI data while controlling for gender and the Five-Factor Model personality traits. In this empirical example, we address the research question: To what extent does homophily of CI plays a role in selecting peers when seeking feedback and to what extent do feedback relationships influence CI? The SAOM shows an homophily effect, which implies that students preferentially seek feedback from others who are similar in CI. We also find an influence effect in which students who seek feedback from one another become more similar in terms of CI over time. Similarity in CI is driven by selection and influence mechanisms in peer feedback networks.
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Sharifpanah, Fatemeh, i Heinrich Sauer. "Stem Cell Spheroid-Based Sprout Assay in Three-Dimensional Fibrin Scaffold: A Novel In Vitro Model for the Study of Angiogenesis". W Methods in Molecular Biology, 179–89. New York, NY: Springer New York, 2016. http://dx.doi.org/10.1007/978-1-4939-3628-1_12.
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Shoushrah, Sarah Hani, Abla Alzagameem, Jonas Bergrath, Edda Tobiasch i Margit Schulze. "Lignin and Its Composites for Tissue Engineering". W Lignin-based Materials, 161–202. The Royal Society of Chemistry, 2023. http://dx.doi.org/10.1039/bk9781839167843-00161.
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Tissue engineering (TE) is a progressive field that aims to provide alternative treatments that bypass drawbacks of conventional medicine. The components of a tissue-engineered construct include commonly a scaffold and cells with or without biochemical molecules. The interactions between these components and the surrounding target tissue determine the success of the construct. Therefore, certain criteria must be met in scaffolds designed for clinical purposes. In this chapter, these criteria will be introduced. Focus is given to lignin, the second most abundant biopolymer on earth. Its availability, biocompatibility, antioxidant and antimicrobial activities, biodegradability, and mechanical properties have attracted the attention of researchers in many applications including biomedical applications. Recent efforts focus on the utilization of lignin as a sustainable building unit for the preparation of scaffold materials. In this chapter, the properties of lignin that contribute to its bioactivity, especially its antioxidant and antimicrobial properties, will be discussed. The benefits of using lignin compared to other materials will be highlighted, followed by addressing the criteria that should be met when designing a lignin-based scaffold. Also, possible cellular compositions of several targeted tissues will be introduced in the context of their natural characteristics within the respective tissue. Another focus will be the possible utilization of various stem cells and their secreted biomolecules for their feasibility as cell sources for scaffolds to be intended for TE. Understanding these tightly orchestrated systems provides an insight into suitable cellular models for testing newly fabricated scaffolds for future applications in clinical settings.
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Martinez-Garza, Mario M., Douglas B. Clark, Stephen S. Killingsworth i Deanne M. Adams. "Beyond Fun". W Advances in Game-Based Learning, 1–32. IGI Global, 2016. http://dx.doi.org/10.4018/978-1-4666-9629-7.ch001.
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A central goal of education involves helping students develop deep understandings of complex models at the heart of core learning goals. Interestingly, an analogous goal of commercial recreational digital games involves helping players develop deep understandings of the models at the heart of those games. Given that games can motivate players to engage voluntarily over extended periods of time in developing understandings of complex game models, one may ask whether and how one might foster similar engagement with educational concepts and models. Much fanfare has accompanied claims about games' potential for engagement and motivation, but many of those claims have focused on a shallow idea of “fun”. This chapter takes a deeper view of motivation and learning by employing Pintrich's synthesis of research on motivation to learn as a lens for examining (a) how popular game design conventions currently scaffold motivation to learn and (b) how game design conventions might be augmented to more effectively scaffold motivation to learn in the future.
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Barrowman, Carole, Patricia Lewis, John C. Savagian i Amy H. Shapiro. "Alverno Accelerate". W New Models of Higher Education: Unbundled, Rebundled, Customized, and DIY, 242–55. IGI Global, 2022. http://dx.doi.org/10.4018/978-1-6684-3809-1.ch012.
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With 50 years of experience in outcome-based, assessment-driven education, Alverno faculty understand the value of student-centered learning as the cornerstone of curriculum design and pedagogical practice. On the scaffold of the authors' experiences as senior faculty in Alverno's curriculum, this chapter explores how pedagogical and pragmatic considerations helped the Alverno Accelerate design team create a program that carefully considers its participants and puts the learner at the center of learning. Alverno Accelerate lets go of many of the canon principles of higher education, welcomes unbundled credits and work/life experiences, and collaborates with adult learners on their individual journeys to their bachelor's degree.
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Welch, Karla Conn, Uttama Lahiri, Zachary E. Warren i Nilanjan Sarkar. "A System to Measure Physiological Response During Social Interaction in VR for Children With ASD". W Computational Models for Biomedical Reasoning and Problem Solving, 1–33. IGI Global, 2019. http://dx.doi.org/10.4018/978-1-5225-7467-5.ch001.
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This chapter presents work aimed at investigating interactions between virtual reality (VR) and children with autism spectrum disorder (ASD) using physiological sensing of affective cues. The research objectives are two-fold: 1) develop VR-based social communication tasks and integrate them into the physiological signal acquisition module to enable the capture of one's physiological responses in a time-synchronized manner during participation in the task and 2) conduct a pilot usability study to evaluate a VR-based social interaction system that induces an affective response in ASD and typically developing (TD) individuals by using a physiology-based approach. Physiological results suggest there is a different physiological response in the body in relation to the reported level of the affective states. The preliminary results from a matched pair of participants could provide valuable information about specific affect-eliciting aspects of social communication, and this feedback could drive individualized interventions that scaffold skills and improve social wellbeing.
Streszczenia konferencji na temat "Scaffold based models"
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Almeida, Henrique A., i Paulo J. Bártolo. "Topological Shear Stress Optimisation of Micro-CT Based Scaffolds". W ASME 2014 12th Biennial Conference on Engineering Systems Design and Analysis. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/esda2014-20433.
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Additive manufacturing technologies are being used to fabricate scaffolds with controlled architecture for tissue engineering applications. These technologies combined with computer-aided design systems enable to produce three-dimensional structures layer-by-layer in a multitude of materials. Actual prediction of the effective mechanical properties of scaffolds produced by Additive manufacturing systems, is very important for tissue engineering applications. One of the existing computer based techniques for scaffold design is topological optimisation. The goal of topological optimisation is to find the best use of material for a body that is subjected to either a single load or a multiple load distribution. This paper proposes a topological optimisation scheme based on existing micro-CT data in order to obtain the ideal topological architectures of scaffolds, maximising its mechanical behaviour under shear stress solicitations. This approach is based on micro-CT data of real biological tissues to create the loading (shear stress) and constraint surfaces of the scaffold during the topological optimisation process. This particular topological optimisation scheme uses the surface boundaries to produce novel models with different characteristics, which are different from the initial micro-CT models. This approach enables to produce valid biomimetic scaffold topologies for tissue engineering applications.
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Bucklen, B., M. Wettergreen, M. Heinkenschloss i M. A. K. Liebschner. "Surface-Based Scaffold Design: A Mechanobiological Approach". W ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-81985.
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Despite recent need-based advances in orthopedic scaffold design, current implants are unsuitable as “total” scaffold replacements. Both mechanical requirements of stiffness/strength and biological stipulations dictating cellular behavior (attachment, differentiation) should be included. The amount of mechanical stimulation in the form of stresses, strains, and energies most suitable toward implant design is presently unknown. Additionally unknown is if whole-bone optimization goals such as uniform and non-uniform driving forces are applicable to a scaffold-bone interface. At the very least, scaffolds ready for implantation should exhibit mechanical distributions (dependent on loading type) on the surface within the typical mechanical usage window. Scaffold micro-architectures can be strategically shifted into that window. The overall goal of this study was to produce microarchitectures tailored to a more uniform mechanical distribution, while maintaining the morphological properties necessary to sustain its mechanical integrity. The mechanical adjustment stimuli investigated were von Mises stress, strain energy density, maximum principle strain, and volumetric strain. Scaffold models of a similar volume fraction were generated of three initial architectures (Rhombitruncated Cuboctahedron, hollow sphere, and trabecular-like bone cube) using high resolution voxel mapping. The resulting voxels were translated into finite element meshes and solved, with a specially written iterative solver created in Fortran90, under confined displacement boundary conditions. The result was verified against a commercial software. Once the mechanical distributions were identified one of two methods was chosen to alter the configuration of material in Cartesian space. The success of the alteration was judged through a diagnostic based on the histogram of mechanical values present on the surface of the micro-architecture. The first method used a compliant approach and, for the case of stress, reinforced locations on the surface with large stresses with extra material (strategically taken from the least stressed portions). The second method used a simulated annealing approach to randomly mutate the initial state in a “temperature” dependent manner. Results indicate that the mechanical distributions of the initial scaffold designs vary significantly. Additionally, the end state of the adjustment demonstrated anisotropy shifts toward the direction of loading. Moreover, the adjustment methods were found to be sensitive both to the mechanical parameter used for adjustment and the portion of the surface adjusted at each increment. In conclusion, scaffolds may be adjusted using a mechanical surface-based objective, as the surface of the scaffold is crucial toward its in vivo acceptance. This technique provides some mathematical specificity toward the whole of computer-aided tissue engineering.
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Starly, Binil, Lauren Shor, Wei Sun i Andrew Darling. "Space Filling Curves: Its Design and Fabrication for Extrusion Based SFF Systems". W ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-79742.
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Scaffolds with designed interior pore architecture, predefined porosity and a well interconnected predetermined network has been the most favored design approach for tissue engineering applications. Solid freeform fabrication technologies have provided the capability of fabricating tissue scaffolds with desired characteristics due to its integration with CAD enabled tools. However, currently the interior macro pore design of scaffolds have been limited to simple regular shapes of either squares or circles due to limited CAD capability. In this paper we seek to enhance the design of the scaffold architecture by using space filling curves within its interior space. The process involves: definition and characterization of space filling curves such as the Hilbert Curve and Sierpinski Curves, applying the principle of layered manufacturing to determine the scaffold individual layered process planes and layered contours; Feasibility studies applying the curve generators to sample models and the generation of fabrication planning instructions for extrusion based SFF systems is presented.
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Bawolin, Nahshon K., i Daniel X. B. Chen. "Elastic Property Monitoring by Radiation Force Impulse and Phase Contrast Imaging". W ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-86952.
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In tissue engineering, one promising methodology is the scaffold based approach, where an artificial construct is seeded with cells, which then proceed to organize and proliferate into new tissue. The scaffold then biodegrades, leaving behind the newly formed tissue that originally developed in the scaffold’s pores. The degradation behavior of the scaffold is critical to its performance during the treatment period, since the decline in scaffold mechanical properties influences the loading of the tissue developing in the scaffold pores, which is known to have an effect on cell behavior. To monitor the scaffold’s mechanical properties, soft scaffolds are deformed by the acoustic radiation force generated by an ultrasound source. Measuring the deflection the scaffold experiences from this ultrasound based radiation force is challenging, since the scaffold is surrounded by the living environment. In this paper, an in-vitro methodology is presented, proceeding from scaffold fabrication, scaffold imaging, image analysis, mathematical equations, and finally model implementation. The innovation comes from the author’s use of in-line phase contrast x-ray imaging at 20 KeV to characterize tissue scaffold deformation from ultrasound radiation forces, and the measured deformation is then compared with predictions given by the forward solution of a mathematical model.
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D’Amore, Antonio, John A. Stella, David E. Schmidt, William R. Wagner i Michael S. Sacks. "A Micro-Architectural Based Structural Model for Elastomeric Electrospun Scaffolds". W ASME 2010 First Global Congress on NanoEngineering for Medicine and Biology. ASMEDC, 2010. http://dx.doi.org/10.1115/nemb2010-13344.
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Interest in electrospun polymeric nano-microfibers for tissue engineering applications has rapidly grown during the last decade. In spite of this technique’s flexibility and ability to form complex fiber assemblies, additional studies are required to elucidate how the fibrous microstructure translates into specific tissue (or meso-scale) level mechanical behavior. Deterministic structural models can quantify how key structures contribute to the mechanical response as a function of bulk deformation across multiple scales, as well as provide a better understanding of cellular mechanical response to local micro-structural deformations. Our ultimate aim is to utilize such models to assist tissue engineering scaffold design. In the current work, we present a novel approach to automatically quantify key micro-architectural descriptors (fiber overlaps, connectivity, orientation, and diameter) from SEM images of electrospun poly (ester urethane) urea (PEUU) to recreate statistically equivalent scaffold mechanical models. An appropriate representative volume element (RVE) size was determined by quantifying the point of stabilization of the architectural descriptors over image areas of increasing size. Material models were then generated specifying: fiber overlap density, fiber orientation, connectivity and fiber diameter. Macro-meso mechanical response was predicted via FEM simulations.
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Parks, W. M., Y. B. Guo i K. A. Woodbury. "Modeling and Assessment of Porosity Effects on Mechanical Properties of Tissue Scaffolds". W ASME 2006 International Manufacturing Science and Engineering Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/msec2006-21040.
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Mechanical properties of scaffolds are important for fabricating engineered tissues. However, localized mechanical properties of scaffold cannot be directly obtained from experiments. This study provides a solid modeling approach to simulate mechanical behaviors of alginate scaffolds with different porosity. A scaffold micro-domain has been modeled as made of sub-units, arranged in a sphere-based pore architecture. An expression to calculate porosity was also derived for the scaffold architecture. Finite element simulations of compressing alginate scaffolds were performed to evaluate the effect of porosity on quasi-static mechanical behavior. The developed FEA model is capable of computing scaffold strength and predicting localized mechanical behavior without destructive materials testing.
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Dishowitz, Michael I., Miltiadis H. Zgonis, Jeremy J. Harris, Constance Ace i Louis J. Soslowsky. "Strength Retention of a New Microbial Cellulose Scaffold and Existing Collagen-Based Scaffolds After In Vivo Implantation in a Rabbit Model". W ASME 2009 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2009. http://dx.doi.org/10.1115/sbc2009-203619.
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Rotator cuff tendon tears often require large tensions for repair [1] and these tensions are associated with poor outcomes including rerupture [2]. To address this, repairs are often augmented with collagen-based scaffolds. Microbial cellulose, produced by A. xylinum as a laminar non-woven matrix, is another candidate for repair augmentation [3]. An ideal augmentation scaffold would shield the repair site from damaging loads as they change throughout the healing process. Although the initial mechanical properties of clinically used scaffolds have been well characterized [4–6], their mechanical behavior following implantation is not known. As a result, the role of these scaffolds throughout the healing process remains unknown. Therefore, the objective of this study is to characterize the mechanical behavior of existing collagen-based scaffolds and a new, microbial cellulose scaffold over time using an in vivo model. We hypothesize that: 1) collagen-based scaffolds will show decreased stiffness (1a) and suture pullout loads (1b) over time when compared to initial values while the microbial cellulose scaffold will not; and 2) the collagen-based scaffolds will have decreased stiffness (2a) and suture pullout loads (2b) when compared to the new, microbial cellulose scaffold at all timepoints.
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Zheng, Zhuoyuan, Zheng Liu, Pingfeng Wang i Yumeng Li. "Design of Three-Dimensional Bi-Continuous Silicon Based Electrode Materials for High Energy Density Batteries". W ASME 2022 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/detc2022-89652.
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Abstract Silicon-based anode is a promising candidate for next generation lithium-ion batteries (LIBs) with improved energy and power density. However, the practical application of Si anode is hindered by their major reliability issue that Si experiences significant volume change during its lithiation/delithiation cycles, leading to high stress, degradation, and pulverization of the anode. With the development of advanced electrode fabrication technologies, structured Si anodes with delicately designed architectures have been proposed. This study focuses on five triply periodic minimal surface (TPMS) based 3D bi-continuous porous Si anodes, which consist of the nano structured metal scaffolds and conformally coated Si layers and explores their lithiation-induced stresses via numerical methods. The multi-physics based finite element (FE) models are firstly built to simulate the deformation and stress of Si anodes during lithiation processes. Afterwards, the Gaussian Processes (GP) based surrogate model is developed to assist the design optimization of the Si anodes within the design space. It is found that, the inverse FCC and diamond surface-based Si anodes show better performances with the lowest stress concentration. In addition, with the decrease of Si phase volume fraction and increase of scaffold fraction, the stresses can be further reduced.
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Slaoui, Idriss, Makeda K. Stephenson, Huma Abdul Rauf, Douglas E. Dow i Sally S. Shady. "Stress Analysis of Bone Scaffold Designed for Segmental Bone Defects". W ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-53398.
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Segmental bone defects result in isolated bone fragments. These defects may be caused by trauma or disease and are a leading cause for orthopedic surgery. Segmental defects pose a challenge as they contain gaps between the ends of bones, which are too large for the regenerating tissue to naturally bridge and repair. A widely used clinical approach to repair such defects is the use of autografts that provide the essential bone growth features. However, autografts generate a secondary deficit in the region from which the graft was harvested. This grafting procedure may result in other complications, such as infections, inflammation, scarring, and bleeding. Synthetic bone scaffolding has been explored as a viable method of helping the body repair segmental bone defects. While synthetic bone scaffolding is a promising approach in orthopedic treatments, limitations exist. Bone is a complex organ with many cell types, emergent, anisotropic, mechanical properties and molecular interactions. Studies have shown that the inner geometries, such as pore size, play an integral role in bone regeneration, cell proliferation, differentiation and recovery. An architecturally-based approach in the design and fabrication of the scaffold may support the differentiation of complex bone tissues. This study developed and tested scaffold designs having different pore size and beam thickness. The designs were developed and simulated for compression and tension in SolidWorks. A hexagonal unit cell was the basis for scaffold design. In one experimental trial (Group 1), the offset of the layers was varied. In another experimental trial (Group 2), the ratio between pore size and beam thickness was varied while using the optimal offset from the former trial. The material for simulation was poly-L-lactic (PLA) acid. In the analysis of the simulation results, the optimal layer offset configuration of 100%,50% in the positive x-y direction showed the lowest stress distribution for both compression and tensile simulations compared to the other offset configurations analyzed. In the second trial of Group 2 models, two models with pore size to beam thickness ratios (7:1 and 8:1) demonstrated low stress distribution under the simulated physiological environments. These results suggest that both models can potentially have different applications in the repair of segmental bone defects.
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Nirmalanandhan, Victor S., Kirsten R. C. Kinneberg, Natalia Juncosa-Melvin, Heather M. Powell, Marepalli Rao, Steven T. Boyce i David L. Butler. "Evaluation of a Novel Scaffold Material for Tendon Tissue Engineering". W ASME 2007 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2007. http://dx.doi.org/10.1115/sbc2007-176294.
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Tissue engineering offers an attractive alternative to direct repair or reconstruction of soft tissue injuries. Tissue engineered constructs containing mesenchymal stem cells (MSCs) seeded in commercially available type I collagen sponges (P1076, Kensey Nash Corporation, Exton, PA) are currently being used within our laboratory to repair tendon injuries in rabbit models [1]. When introduced into the wound site, mechanically stimulated stem cell-collagen sponge constructs exhibit 50% greater maximum force and stiffness at 12 weeks compared to values for static controls [1]. However, these constructs often lack the maximum force sufficient to resist the peak in vivo forces acting on the repair site [2, 3]. Insufficient repair biomechanics can be attributed to the poor initial mechanical resistance provided by the collagen sponges to replace the function of the lost tendon before its degradation and replacement with new extracellular matrix. This current study seeks to identify a biologically-derived scaffold with improved mechanical integrity that could be used in stem cell-based tissue engineered constructs for tendon repair.
Raporty organizacyjne na temat "Scaffold based models"
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Matera, Carola. Incorporating Scaffolded Dialogic Reading Practice in Teacher Training: An Opportunity to Improve Instruction for Young Dual Language Learners in Transitional Kindergarten. Loyola Marymount University, 2015. http://dx.doi.org/10.15365/ceel.policy.4.
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Findings from a joint collaborative between the Center for Equity for English Learners (CEEL) at Loyola Marymount University and the Los Angeles Unified School District (LAUSD) to provide professional development and coaching to Transitional Kindergarten (TK) teachers on the Scaffolded Dialogic Reading (SDR) are presented in this policy brief. SDR is a method to enhance language skills through dialogue and research-based scaffolds between teachers and small groups of children mediated through repeated readings of storybooks. The purpose of this brief is to: 1) state the opportunity to ensure Dual Language Learner (DLL) support within California’s TK policy; 2) provide a synthesis of research findings; and 3) provide TK professional learning and policy recommendations that would allow for the inclusion of professional development on evidence-based practices purposefully integrated with DLL supports. Policy recommendations include: 1) utilize professional learning modules such as SDR in 24 ECE unit requirement for TK teachers; 2) include individuals with ECE and DLL expertise in the ECE Teacher Preparation Advisory Panel; and 3) allocate additional funds in the state budget for training on SDR, in-classroom support for TK teachers of DLLs, and evaluation of these efforts.
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Altstein, Miriam, i Ronald J. Nachman. Rational Design of Insect Control Agent Prototypes Based on Pyrokinin/PBAN Neuropeptide Antagonists. United States Department of Agriculture, sierpień 2013. http://dx.doi.org/10.32747/2013.7593398.bard.
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The general objective of this study was to develop rationally designed mimetic antagonists (and agonists) of the PK/PBAN Np class with enhanced bio-stability and bioavailability as prototypes for effective and environmentally friendly pest insect management agents. The PK/PBAN family is a multifunctional group of Nps that mediates key functions in insects (sex pheromone biosynthesis, cuticular melanization, myotropic activity, diapause and pupal development) and is, therefore, of high scientific and applied interest. The objectives of the current study were: (i) to identify an antagonist biophores (ii) to develop an arsenal of amphiphilic topically active PK/PBAN antagonists with an array of different time-release profiles based on the previously developed prototype analog; (iii) to develop rationally designed non-peptide SMLs based on the antagonist biophore determined in (i) and evaluate them in cloned receptor microplate binding assays and by pheromonotropic, melanotropic and pupariation in vivo assays. (iv) to clone PK/PBAN receptors (PK/PBAN-Rs) for further understanding of receptor-ligand interactions; (v) to develop microplate binding assays for screening the above SMLs. In the course of the granting period A series of amphiphilic PK/PBAN analogs based on a linear lead antagonist from the previous BARD grant was synthesized that incorporated a diverse array of hydrophobic groups (HR-Suc-A[dF]PRLa). Others were synthesized via the attachment of polyethylene glycol (PEG) polymers. A hydrophobic, biostablePK/PBAN/DH analog DH-2Abf-K prevented the onset of the protective state of diapause in H. zea pupae [EC50=7 pmol/larva] following injection into the preceding larval stage. It effectively induces the crop pest to commit a form of ‘ecological suicide’. Evaluation of a set of amphiphilic PK analogs with a diverse array of hydrophobic groups of the formula HR-Suc-FTPRLa led to the identification of analog T-63 (HR=Decyl) that increased the extent of diapause termination by a factor of 70% when applied topically to newly emerged pupae. Another biostablePK analog PK-Oic-1 featured anti-feedant and aphicidal properties that matched the potency of some commercial aphicides. Native PK showed no significant activity. The aphicidal effects were blocked by a new PEGylated PK antagonist analog PK-dF-PEG4, suggesting that the activity is mediated by a PK/PBAN receptor and therefore indicative of a novel and selective mode-of-action. Using a novel transPro mimetic motif (dihydroimidazole; ‘Jones’) developed in previous BARD-sponsored work, the first antagonist for the diapause hormone (DH), DH-Jo, was developed and shown to block over 50% of H. zea pupal diapause termination activity of native DH. This novel antagonist development strategy may be applicable to other invertebrate and vertebrate hormones that feature a transPro in the active core. The research identifies a critical component of the antagonist biophore for this PK/PBAN receptor subtype, i.e. a trans-oriented Pro. Additional work led to the molecular cloning and functional characterization of the DH receptor from H. zea, allowing for the discovery of three other DH antagonist analogs: Drosophila ETH, a β-AA analog, and a dF analog. The receptor experiments identified an agonist (DH-2Abf-dA) with a maximal response greater than native DH. ‘Deconvolution’ of a rationally-designed nonpeptide heterocyclic combinatorial library with a cyclic bis-guanidino (BG) scaffold led to discovery of several members that elicited activity in a pupariation acceleration assay, and one that also showed activity in an H. zea diapause termination assay, eliciting a maximal response of 90%. Molecular cloning and functional characterization of a CAP2b antidiuretic receptor from the kissing bug (R. prolixus) as well as the first CAP2b and PK receptors from a tick was also achieved. Notably, the PK/PBAN-like receptor from the cattle fever tick is unique among known PK/PBAN and CAP2b receptors in that it can interact with both ligand types, providing further evidence for an evolutionary relationship between these two NP families. In the course of the granting period we also managed to clone the PK/PBAN-R of H. peltigera, to express it and the S. littoralis-R Sf-9 cells and to evaluate their interaction with a variety of PK/PBAN ligands. In addition, three functional microplate assays in a HTS format have been developed: a cell-membrane competitive ligand binding assay; a Ca flux assay and a whole cell cAMP ELISA. The Ca flux assay has been used for receptor characterization due to its extremely high sensitivity. Computer homology studies were carried out to predict both receptor’s SAR and based on this analysis 8 mutants have been generated. The bioavailability of small linear antagonistic peptides has been evaluated and was found to be highly effective as sex pheromone biosynthesis inhibitors. The activity of 11 new amphiphilic analogs has also been evaluated. Unfortunately, due to a problem with the Heliothis moth colony we were unable to select those with pheromonotropic antagonistic activity and further check their bioavailability. Six peptides exhibited some melanotropic antagonistic activity but due to the low inhibitory effect the peptides were not further tested for bioavailability in S. littoralis larvae. Despite the fact that no new antagonistic peptides were discovered in the course of this granting period the results contribute to a better understanding of the interaction of the PK/PBAN family of Nps with their receptors, provided several HT assays for screening of libraries of various origin for presence of PK/PBAN-Ragonists and antagonists and provided important practical information for the further design of new, peptide-based insecticide prototypes aimed at the disruption of key neuroendocrine physiological functions in pest insects.
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Altstein, Miriam, i Ronald Nachman. Rationally designed insect neuropeptide agonists and antagonists: application for the characterization of the pyrokinin/Pban mechanisms of action in insects. United States Department of Agriculture, październik 2006. http://dx.doi.org/10.32747/2006.7587235.bard.
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The general objective of this BARD project focused on rationally designed insect neuropeptide (NP) agonists and antagonists, their application for the characterization of the mechanisms of action of the pyrokinin/PBAN (PK-PBAN) family and the development of biostable, bioavailable versions that can provide the basis for development of novel, environmentally-friendly pest insect control agents. The specific objectives of the study, as originally proposed, were to: (i) Test stimulatory potencies of rationally designed backbone cyclic (BBC) peptides on pheromonotropic, melanotropic, myotropic and pupariation activities; (ii) Test the inhibitory potencies of the BBC compounds on the above activities evoked either by synthetic peptides (PBAN, LPK, myotropin and pheromonotropin) or by the natural endogenous mechanism; (iii) Determine the bioavailability of the most potent BBC compounds that will be found in (ii); (iv) Design, synthesize and examine novel PK/PBAN analogs with enhanced bioavailability and receptor binding; (v) Design and synthesize ‘magic bullet’ analogs and examine their ability to selectively kill cells expressing the PK/PBAN receptor. To achieve these goals the agonistic and antagonistic activities/properties of rationally designed linear and BBC neuropeptide (NP) were thoroughly studied and the information obtained was further used for the design and synthesis of improved compounds toward the design of an insecticide prototype. The study revealed important information on the structure activity relationship (SAR) of agonistic/antagonistic peptides, including definitive identification of the orientation of the Pro residue as trans for agonist activity in 4 PK/PBANbioassays (pheromonotropic, pupariation, melanotropic, & hindgut contractile) and a PK-related CAP₂b bioassay (diuretic); indications that led to the identification of a novel scaffold to develop biostbiostable, bioavailable peptidomimetic PK/PBANagonists/antagonists. The work led to the development of an arsenal of PK/PBAN antagonists with a variety of selectivity profiles; whether between different PKbioassays, or within the same bioassay between different natural elicitors. Examples include selective and non-selective BBC and novel amphiphilic PK pheromonotropic and melanotropic antagonists some of which are capable of penetrating the moth cuticle in efficacious quantities. One of the latter analog group demonstrated unprecedented versatility in its ability to antagonize a broad spectrum of pheromonotropic elicitors. A novel, transPro mimetic motif was proposed & used to develop a strong, selective PK agonist of the melanotropic bioassay in moths. The first antagonist (pure) of PK-related CAP₂b diuresis in flies was developed using a cisPro mimetic motif; an indication that while a transPro orientation is associated with receptor agonism, a cisPro orientation is linked with an antagonist interaction. A novel, biostablePK analog, incorporating β-amino acids at key peptidase-susceptible sites, exhibited in vivo pheromonotropic activity that by far exceeded that of PBAN when applied topically. Direct analysis of neural tissue by state-of-the-art MALDI-TOF/TOF mass spectrometry was used to identify specific PK/PK-related peptides native to eight arthropod pest species [house (M. domestica), stable (S. calcitrans), horn (H. irritans) & flesh (N. bullata) flies; Southern cattle fever tick (B. microplus), European tick (I. ricinus), yellow fever mosquito (A. aegypti), & Southern Green Stink Bug (N. viridula)]; including the unprecedented identification of mass-identical Leu/Ile residues and the first identification of NPs from a tick or the CNS of Hemiptera. Evidence was obtained for the selection of Neb-PK-2 as the primary pupariation factor of the flesh fly (N. bullata) among native PK/PK-related candidates. The peptidomic techniques were also used to map the location of PK/PK-related NP in the nervous system of the model fly D. melanogaster. Knowledge of specific PK sequences can aid in the future design of species specific (or non-specific) NP agonists/antagonists. In addition, the study led to the first cloning of a PK/PBAN receptor from insect larvae (S. littoralis), providing the basis for SAR analysis for the future design of 2ⁿᵈgeneration selective and/or nonselective agonists/antagonists. Development of a microplate ligand binding assay using the PK/PBAN pheromone gland receptor was also carried out. The assay will enable screening, including high throughput, of various libraries (chemical, molecular & natural product) for the discovery of receptor specific agonists/antagonists. In summary, the body of work achieves several key milestones and brings us significantly closer to the development of novel, environmentally friendly pest insect management agents based on insect PK/PBANNPs capable of disrupting critical NP-regulated functions.