Bibliographies thématiques / Bio-aggregate

Sommaire

Articles de revues
Thèses
Livres
Chapitres de livres
Actes de conférences

Littérature scientifique sur le sujet « Bio-aggregate »

Auteur : Grafiati

Publié le 25 janvier 2025

Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres

Choisissez une source :

Consultez les listes thématiques d’articles de revues, de livres, de thèses, de rapports de conférences et d’autres sources académiques sur le sujet « Bio-aggregate ».

À côté de chaque source dans la liste de références il y a un bouton « Ajouter à la bibliographie ». Cliquez sur ce bouton, et nous générerons automatiquement la référence bibliographique pour la source choisie selon votre style de citation préféré : APA, MLA, Harvard, Vancouver, Chicago, etc.

Vous pouvez aussi télécharger le texte intégral de la publication scolaire au format pdf et consulter son résumé en ligne lorsque ces informations sont inclues dans les métadonnées.

Articles de revues sur le sujet "Bio-aggregate"

Ferreira, Saulo Rocha, Rodolfo Giacomim Mendes de Andrade, Gabriele Melo de Andrade, Olga Maria Oliveira de Araújo, Ricardo Tadeu Lopes, Eduardo de Moraes Rego Fairbairn, Thiago Melo Grabois et Neven Ukrainczyk. « Bond Behavior of a Bio-Aggregate Embedded in Cement-Based Matrix ». Materials 15, n^o 17 (5 septembre 2022) : 6151. http://dx.doi.org/10.3390/ma15176151.

Texte intégral

Résumé :

This paper investigates the bond behavior between a bio-aggregate and a cement-based matrix. The experimental evaluation comprised physical, chemical, image, and mechanical characterization of the bio-aggregate. The image analyses about the bio-aggregate’s outer structure provided first insights to understand the particularities of this newly proposed bio-aggregate for use in cementitious materials. A mineral aggregate (granitic rock), largely used as coarse aggregate in the Brazilian civil construction industry, was used as reference. The bond behavior of both aggregates was evaluated via pull-out tests. The results indicated that both aggregates presented a similar linear elastic branch up to each respective peak loads. The peak load magnitude of the mineral aggregate indicated a better chemical adhesion when compared to the bio-aggregate’s. The post-peak behavior, however, indicated a smoother softening branch for the bio-aggregate, corroborated by the microscopy image analyses. Although further investigation is required, the macaúba crushed endocarp was found to be a thriving bio-material to be used as bio-aggregate.

Styles APA, Harvard, Vancouver, ISO, etc.

Zhu, Lixia, Mengmeng Cao, Chengchen Sang, Tingxuan Li, Yanjun Zhang, Yunxia Chang et Lili Li. « Trichoderma Bio-Fertilizer Decreased C Mineralization in Aggregates on the Southern North China Plain ». Agriculture 12, n^o 7 (11 juillet 2022) : 1001. http://dx.doi.org/10.3390/agriculture12071001.

Texte intégral

Résumé :

Trichoderma bio-fertilizer is widely used to improve soil fertility and carbon (C) sequestration, but the mechanism for increasing C accumulation remains unclear. In this study, effects of Trichoderma bio-fertilizer on the mineralization of aggregate-associated organic C were investigated in a field experiment with five treatments (bio-fertilizer substitute 0 (CF), 10% (BF10), 20% (BF20), 30% (BF30) and 50% (BF50) chemical fertilizer nitrogen (N)). Aggregate fractions collected by the dry sieving method were used to determine mineralization dynamics of aggregate-associated organic C. The microbial community across aggregate fractions was detected by the phospholipid fatty acid (PLFA) method. The results indicated that Trichoderma bio-fertilizer increased organic C stock across aggregate fractions and bulk soil compared with CF. Cumulative mineralization of aggregate-associated organic C increased with the increasing bio-fertilizer application rate. However, the proportion of organic mineralized C was lower in the BF20 treatment except for <0.053 mm aggregate. Moreover, the PLFAs and fungal PLFA/bacterial PLFA first increased and then decreased with increasing bio-fertilizer application rates. Compared with CF, the increases of bacteria PLFA in >2 mm aggregate were 79.7%, 130.0%, 141.0% and 148.5% in BF10, BF20, BF30 and BF50, respectively. Similarly, the PLFAs in 0.25–2, 0.053–0.25 and <0.053 mm aggregates showed a similar trend to that in >2 mm aggregate. Bio-fertilizer increased the value of fungi PLFA/bacteria PLFA but decreased G+ PLFA/G− PLFA, and BF20 shared the greatest changes. Therefore, appropriate Trichoderma bio-fertilizer application was beneficial to improving soil micro-environment and minimizing risks of soil degradation.

Styles APA, Harvard, Vancouver, ISO, etc.

Huang, Gang, Ariane Abou-Chakra, Sandrine Geoffroy et Joseph Absi. « A Multi-Scale Numerical Simulation on Thermal Conductivity of Bio-Based Construction Materials ». Construction Materials 2, n^o 3 (4 juillet 2022) : 148–65. http://dx.doi.org/10.3390/constrmater2030011.

Texte intégral

Résumé :

Amid increasing concern about carbon emissions and ENERGY consumption in the building industry, bio-based construction materials are one of the solutions, especially considering their excellent thermal insulation. This study aims to develop a multi-scale numerical model to analyze the effect of microstructure on the thermal conductivity of a bio-based construction material. To achieve this, the size, shape, orientation, porosity, and water saturation of the bio-aggregate were considered in this study. The results show that the thermal conductivity of the bio-based material increases significantly and nonlinearly with water saturation, in contrast to the parallel thermal conductivity of the transversely isotropic bio-aggregate, which increases linearly. The thermal conductivity of the bio-based material shows an anisotropy in different directions and it obtains a maximum at water saturation of 0.4. Analysis of inclusions with different shapes shows that the thermal conductivity in the compaction direction is almost independent of the shape, but not in the direction perpendicular to the compaction. The finite element results show that the heat flow tends to transfer along the bio-aggregate rather than across it. These findings help to better understand the effect of microstructure on thermal conductivity and then promote the application of bio-based concrete as an insulation material in buildings.

Styles APA, Harvard, Vancouver, ISO, etc.

Amantino, Guilherme Miguel, Nicole Pagan Hasparyk, Francieli Tiecher et Romildo Dias Toledo Filho. « Assessment of bio-aggregate concretes’ properties with rice residue ». Journal of Building Engineering 52 (juillet 2022) : 104348. http://dx.doi.org/10.1016/j.jobe.2022.104348.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

da Silva, Bruno Tiago Angelo, et Suelly Helena de Araújo Barroso. « The Application of Soy Biodiesel in Bituminous Priming of Soil-Aggregate Layers of Low Traffic Volume Roads in the State of Ceara, Brazil ». Advanced Materials Research 875-877 (février 2014) : 115–25. http://dx.doi.org/10.4028/www.scientific.net/amr.875-877.115.

Texte intégral

Résumé :

This work investigates the potential of penetration, in terms of bituminous prime coat, of an asphalt mixture produced adding Soy Biodiesel [BIO] to the Asphalt Cement [AC] to be used in low traffic volume roads in the state of Ceara, Brazil. The main objective of this investigation was finding a less polluting alternative, by replacing kerosene, usually applied as diluent of AC in the traditional mixture CM-30. Therefore, a comparative study was made between the traditional binder [CM-30] and the proposed mixture [40% of Soy Biodiesel and 60% of AC 50/70], named as AC/BIO. Both tested binders were used in specimens made by the stabilization of a sandy soil, adding 50% and 60% of construction and demolition waste, resulting in two different soil-aggregate mixtures. The research considered some factors that influence the extent of penetration of the prime coat: moisture content of the base, type and volume of binder used and compaction energy. The characterization of the materials used in this research included tests such as the gradation of the aggregates, CBR and Resilient Modulus of the mixtures soil/aggregate, viscosity Saybolt-Furol and penetration of the binders (traditional and AC/BIO) in the samples of soil/aggregate. The results showed that the penetration potential of the AC/BIO mixture was similar to the CM-30 keeping the technical viability.

Styles APA, Harvard, Vancouver, ISO, etc.

Yew, M. K., M. C. Yew, J. H. Beh, L. H. Saw, Y. L. Lee, J. H. Lim et C Y T. « Fire resistance of lightweight foam concrete by incorporating lightweight bio-based aggregate ». IOP Conference Series : Earth and Environmental Science 920, n^o 1 (1 novembre 2021) : 012009. http://dx.doi.org/10.1088/1755-1315/920/1/012009.

Texte intégral

Résumé :

Abstract Concrete is widely used in the industry due to its effectiveness in terms of cost and strength. In this study, the introduction of bio-based aggregate as coarse aggregate in lightweight foam concrete will be investigated to find a better solution for fire incidents that are commonly happened. As such, lightweight foam concrete (LWFC) has been applied in many buildings especially in non-load bearing wall to enhance thermal conductivity, sound insulation and fire resistance. The aim of this research is to investigate the effect of incorporating bio-based aggregate namely oil palm shell (OPS) into lightweight form concrete in terms of strength properties and fire resistance. Three different concrete mix was designed containing different percentage of OPS aggregate replacement (0, 5, 10 and 15%). From the result, the compressive strength of the LWFC-CTR mixture had achieved the highest compressive strength at 28-day, which is recorded at 3.82 MPa. The fire resistance of LWFC-OPS 15% had showed a positive outcome with improvement by almost 23.5% compared to control mix at 15 minutes. Therefore, the major finding of this research is the incorporation of eco-friendly OPS aggregate has improved the fire resistance of lightweight foam concrete, which can be used as an alternative solution for non-load bearing walls.

Styles APA, Harvard, Vancouver, ISO, etc.

Peng, Yuanyuan, He Zhang, Jinshan Lian, Wen Zhang, Guihua Li et Jianfeng Zhang. « Combined Application of Organic Fertilizer with Microbial Inoculum Improved Aggregate Formation and Salt Leaching in a Secondary Salinized Soil ». Plants 12, n^o 16 (15 août 2023) : 2945. http://dx.doi.org/10.3390/plants12162945.

Texte intégral

Résumé :

Greenhouse vegetable production provides significant quantities of vegetables throughout the year and improves farmers’ income. However, over-fertilization with mineral fertilizer causes soil secondary salinization and decreases the stability of the soil structure. To improve aggregate formation and decrease salt accumulation in the soil profile, bio-organic fertilizers (Protaetia brevitarsis larvae frass with Bacillus amyloliticus and/or Trichoderma harziensis) were applied to partially substitute mineral fertilizer in a salinized vegetable soil. Soil nutrient condition, aggregate stability, and salt movement in the soil profile were measured in a greenhouse double-cucumber system. The results showed that soil organic matter (SOM), total nitrogen (TN), and available phosphorus (AP) increased significantly under bio-organic fertilizer treatments compared with control. Soil electrical conductivity (EC) and total salt content (TSC) decreased by 15.74–24.20% and 19.15–29.05%, respectively, with bio-organic fertilizers (p < 0.05). Cl−, NO3−, and SO42− content under double inoculation with B. amyloliticus and T. harziensis reduced by 31.19%, 26.30%, and 53.11%, respectively, compared to CK (p < 0.05). In addition, double inoculation was more efficient in reducing nitrate content in the soil profile than single inoculation. Soil microaggregates of 0.25–0.053 mm increased by 75.87–78.51% with bio-fertilizers compared with control, and double inoculation was the best for aggregate formation. In conclusion, the inoculation of plant-growth-promoting and salt-tolerant microorganisms with high humic acid larvae frass can alleviate salinization in vegetable soil, enhance soil nutrient content, and improve the soil structure.

Styles APA, Harvard, Vancouver, ISO, etc.

Khushnood, Rao Arsalan, Zarar Ali Qureshi, Nafeesa Shaheen et Sikandar Ali. « Bio-mineralized self-healing recycled aggregate concrete for sustainable infrastructure ». Science of The Total Environment 703 (février 2020) : 135007. http://dx.doi.org/10.1016/j.scitotenv.2019.135007.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Hariz, Samah, Fouad Ghomari et Brahim Touil. « Characterization of a bio-based concrete using virgin cork aggregate ». Journal of Building Materials and Structures 9, n^o 2 (29 décembre 2022) : 141–49. http://dx.doi.org/10.34118/jbms.v9i2.2780.

Texte intégral

Résumé :

The field of construction, like other field besides, faces new challenges, particularly that relating to reduction of the environmental impact and the improvement of the thermal and energy performances. To this end, the work presented in this article concerns bio-based concrete which complies with the new regulatory provisions inherent in cementitious materials. This is a concrete where 25% of the mineral volume is replaced by the same plant volume (male cork) in the dry state and immersed for 2 hours in water while adding 10% of filler. A first experimental campaign was carried out in the laboratory in order to identify the rheological behavior of the composite in the fresh state and the mechanical behavior in the hardened state. The results showed that this material can be used in many civil engineering applications.

Styles APA, Harvard, Vancouver, ISO, etc.

Bellei, Poliana, Fernanda Magalhães, Manuel Pereira, Isabel Torres, Runar Solstad et Inês Flores-Colen. « Innovative Thermal Renders Incorporating Oyster Shells for Sustainable Insulation ». Sustainability 15, n^o 22 (15 novembre 2023) : 15952. http://dx.doi.org/10.3390/su152215952.

Texte intégral

Résumé :

In accordance with current sustainable development objectives, it is intended to implement innovative and sustainable solutions at economic, environmental, and functional levels, boosting the construction sector to increasingly contribute to society. Expanded cork is an alternative to sand aggregate in improving the thermal insulating properties of renders. In addition, other materials can be incorporated as aggregates in an attempt to contribute to both the improvement of the physical characteristics that the render must fulfil as well as the improvement of thermal behaviour (if possible). In this sense, bio-based materials generated by the aquaculture sector, such as oyster shells, can contribute as a bio-based insulation material for thermal renders. In this study, thermal natural hydraulic lime mortars were produced from a mixture of expanded cork (EC) insulating aggregate and oyster shells (OSs). The percentages of replacing EC by OSs were 20, 30, 40, and 50%. The tests were carried out in fresh and hardened states. The studied mortars presented a thermal conductivity and compressive strength of 0.151 W/(m·K) and 0.63 MPa, respectively. The most interesting performance between thermal conductivity and compressive strength was for the composite with 50% of each bio-based material. The potential of incorporating oyster shells as a bio-based insulation material could contribute to a sustainable blue circular economy.

Styles APA, Harvard, Vancouver, ISO, etc.

Plus de sources

Thèses sur le sujet "Bio-aggregate"

Guidi, Claudia. « Soil organic carbon responses to forest expansion on mountain grasslands ». Doctoral thesis, country:DK, 2015. http://hdl.handle.net/10449/25091.

Texte intégral

Résumé :

Grassland abandonment followed by progressive forest expansion is the dominant land-use change in the European Alps. Contrasting trends in soil organic carbon (SOC) stocks have been reported for mountainous regions following forest expansion on grasslands. Moreover, its effects on SOC properties involved into long-term stability are largely unknown. The aim of this PhD thesis was to explore changes in: (i) SOC stocks; (ii) physical SOC fractions and their sensitivity to SOC changes; and (iii) labile carbon (C) in soil and fractions following forest expansion on mountain grasslands. A land-use gradient located in the Southern Alps (Italy) was examined, comprising managed grassland, two transitional phases in which grassland abandonment led to colonization by Picea abies (L.) Karst., and old forest dominated by Fagus sylvatica L. and P. abies. Organic and mineral soil layers were collected within three plots for each successional stage. Soil samples were fractionated according to: (i) aggregate size fractionation, separating aggregates through wet-sieving, and (ii) size-density fractionation, separating stable aggregates from particulate organic matter (POM) non-occluded within aggregates. Changes in labile soil C were assessed by analysis of carbohydrate monomers and by thermal analysis of soil and size-density fractions. Our study showed that mineral SOC stocks were lower in early-stage and old forest (-28% in the top 10 cm of mineral soil) than in managed and abandoned grassland. The SOC accumulation within the organic layers following forest establishment could not fully compensate the mineral SOC stock difference between forest and grassland successional stages. The dimension of aggregates assessed by aggregate size fractionation tended to increase, while SOC allocation to stable aggregates assessed by size-density fractionation decreased following conversion of grassland to forest (e.g from 81 to 59% in the 0-5 cm layer). Higher SOC allocation to POM fraction in the mineral soil, together with changed carbon distribution between mineral and organic soil layers, suggest an overall decrease in physical SOC protection and a concomitant shift to unprotected SOC fractions. The size-density fractions showed higher sensitivity to SOC changes than aggregate size fractions and therefore may be better suited for the detection of SOC changes. Carbohydrate and thermal analyses indicated higher shares of labile soil C in grassland abandoned since 10 years than in managed grassland and forest successional stages. Ratios of 6 microbially to plant-derived carbohydrates decreased from grassland to forest successional stages, and corresponded to decreased SOC allocation to stable aggregates. Forest expansion on mountain grasslands caused a decrease in SOC stocks within the mineral soil and in physically protected SOC fractions, which can be explained by lower accumulation of binding agents of microbial origin. This can have implications for the accumulation of atmospheric CO2 in soil and for the susceptibility of SOC to external disturbances such as management and environmental changes.

Styles APA, Harvard, Vancouver, ISO, etc.

Coulombe, Charles. « Développement de méthodes et d'outils bio-informatiques pour l'analyse de données génomiques ». Mémoire, Université de Sherbrooke, 2017. http://hdl.handle.net/11143/10519.

Texte intégral

Résumé :

Dans ce mémoire, je présenterai les outils que nous avons développés dans le cadre de ma maîtrise. Tout d'abord, je présenterai un outil d'analyse de données génomiques nommé Versatile Aggregrate Profiler (VAP). Ensuite, je présenterai un outil d'identification de profils agrégés similaires nommé vap_sim ainsi que la méthodologie utilisée afin d'obtenir un paramétrage adéquat de l'outil pouvant s'adapter assez facilement aux différents profils agrégés. Au troisième chapitre, je présenterai un outil de validation de formats génomiques nommé Genomic Format Validator (GFV) permettant d'identifier simplement et rapidement les erreurs de structure et de logique dans un fichier de données génomiques. Finalement, au dernier chapitre, je présenterai trois outils complémentaires à VAP.

Styles APA, Harvard, Vancouver, ISO, etc.

Rosa, Latapie Séverine. « Modélisation et optimisation des performances thermiques des matériaux bio et géosourcés par approche multi-échelle : apport à la valorisation d'une large gamme de co-produits agricoles ». Electronic Thesis or Diss., Université de Toulouse (2023-....), 2024. http://www.theses.fr/2024TLSES152.

Texte intégral

Résumé :

Face aux défis du 21° siècle, les questions énergétiques et environnementales sont au cœur des préoccupations de nos sociétés. Le secteur du bâtiment, parmi les plus impactants, doit s'emparer de cette réalité pour opérer une transition à la fois rapide, pertinente et durable. L'utilisation de matériaux de construction bio et géo-sourcés permet d'améliorer le confort intérieur et l'efficacité énergétique du bâti tout diminuant l'impact environnemental de la construction. Dans ce cadre, le béton de chanvre est une alternative prometteuse qui se développe depuis plusieurs années. Cependant, de nombreux co-produits agricoles -autres que la chènevotte- peuvent être valorisés dans les matériaux de construction. Ces derniers sont, de surcroît, largement disponibles grâce aux différentes cultures implantées localement (tournesol, colza, lin, ...). Toutefois, de nombreux freins expliquent l'assurabilité délicate de ces éco-matériaux, ce qui limite aujourd'hui leur utilisation à grande échelle à des fins d'isolation répartie. Leur comportement complexe, face aux variations de température et d'humidité relative, est probablement un des principaux verrous à lever. Ces travaux de thèse visent donc à mieux comprendre les phénomènes physiques qui s'opèrent dans ces matériaux, à les modéliser et à proposer des modèles de prédiction de leur comportement thermique. Ils s'appuient principalement sur des techniques d'homogénéisation analytique (Mori Tanaka et Double Inclusion) permettant de considérer la variabilité de la conductivité thermique sous les contraintes d'usage. La considération d'une échelle stratégique, celle de la particule végétale, permet une application étendue à une large gamme de co-produits agricoles. Ainsi, l'analyse multi-échelle proposée permet de prédire et d'optimiser le comportement thermo-hygrique de ces éco-matériaux avant même l'étape de fabrication et en appui des travaux expérimentaux. Ces travaux devraient favoriser l'émergence d'économies locales autour de matériaux de construction sains, efficaces et écologique. Ils constituent des leviers stratégiques à la réduction des émissions de gaz à effet de serre visée par le Pacte Vert pour l'Europe, d'ici 2030
The challenges of the 21st century require energy and environmental issues to be central concerns for society. The building sector, one of the most environmentally-impacting, must seize this opportunity to ensure a rapid, relevant and sustainable transition. The use of bio- and geo-based building materials allows improvements in indoor comfort and energy efficiency to be achieved, while reducing the building environmental impact. Hemp concrete is a promising alternative which has been developing for several years. However, many agricultural by-products - other than hemp shives - can be used in construction materials. Moreover, they are widely available thanks to the various local crops (sunflower, rapeseed, flax, etc.). Nevertheless, numerous obstacles explain the delicate insurability of these eco-materials, which currently limits their large-scale use for distributed insulation. Their complex behavior, when subjected to temperature and relative humidity variations, is probably one of the main obstacles to be overcome. The aim of this thesis work is therefore to gain a better understanding of the physical phenomena involved in these materials, to model them and to propose models for predicting their thermal behavior. It is mainly based on analytical homogenization techniques (Mori Tanaka and Double Inclusion) allowing the variability of thermal conductivity to be taken into account under use conditions. By considering a strategic scale, the plant particle one, it is possible to extend the approach to a wide range of agricultural co-products. The proposed multi-scale analysis enables the thermo-hygric behavior of these eco-materials to be predicted and optimized even before the manufacturing stage, and as a support for experimental work. This research is expected to encourage the emergence of local economies based on healthy, efficient and environmentally-friendly construction materials. They represent strategic levers in the reduction of greenhouse gas emissions targeted by the Green Pact for Europe between now and 2030

Styles APA, Harvard, Vancouver, ISO, etc.

MURRU, VALENTINA. « Comparative studies on the Silene mollissima aggregate (Caryophyllaceae) ». Doctoral thesis, Università degli Studi di Cagliari, 2017. http://hdl.handle.net/11584/248709.

Texte intégral

Résumé :

In this PhD thesis, a multidisciplinary approach was adopted to contribute to the knowledge of some taxa of the Silene mollissima aggregate and to provide useful information and data to support conservation measures. In Chapter I, a statistical classifier for the Tyrrhenian taxa of the S. mollissima aggregate (Silene badaroi, Silene ichnusae, Silene velutina, Silene oenotriae, Silene hicesiae), based on 132 morpho-colorimetric variables describing seed size, shape and color of seed, was tested at inter- and intra-specific levels. The performed analysis confirmed the systematic treatment at section and species level. At the population level both the presence of connections and high differentiation rates among populations were identified. In particular, the most differentiated populations, both for S. velutina and S. badaroi, were those at the edge of the species’ distribution area; indeed, seeds from populations of the core areas of distribution ranges were less different among each other. In Chapters II and III, relevant information was reported about phenology and ecological requirements of some Tyrrhenian (S. velutina, S. ichnusae and S. badaroi) and Ibero-Levantine species (Silene mollissima and Silene hifacensis) of the S. mollissima aggregate, providing germination and seedling growth protocols useful for their ex situ propagation and conservation. Seeds germination of the three Tyrrhenian species was improved by light and occurred with high percentages at the lowest tested temperatures (5-15°C) and under the alternating temperature regime (25/10 °C). Silene velutina and S. ichnusae seeds germinated until 300 mM NaCl, while S. badaroi up to 100 mM. Except for S. badaroi, salt did not affect seed viability and recovery. The addiction of KNO3 did not affect germination of the three species and their recovery under saline conditions. Seeds germination of the two Ibero-Levantine species was not affected by photoperiod. For both studied species seeds germination rates were higher at the lowest tested temperatures (10 and 15°C). The two species were able to germinate up to 250 mM NaCl, but inter-population differences were detected in the tolerance limit. The highest germination occurred in the non-saline control and decreased with increasing salinity. Silene mollissima and S. hifacensis seeds totally recovered their germination after the NaCl exposure. For both S. mollissima populations the increasing temperature promoted the seedling dry weight and the growth rate, while this pattern was observed only for one S. hifacensis population. In Chapter IV, by taking into account several environmental and population parameters, the microniche variation and the niche breadth dynamics, at local and regional scales, were investigated in Mediterranean islands of different size (large and small islands; LI and SI, respectively) for the Sardinian-Corsican endemic S. velutina. As regards SI populations, a realized niche characterized by harsh and homogeneous environments, with low disturbance levels and potentially low competition was detected, where the life-history strategy of populations was based more on the persistence of adult individuals than on recruitment of juveniles. In contrast, LI populations showed a highly heterogeneous ecological niche, characterized by higher levels of biodiversity, plant cover and the presence of woody vegetation. Such a realized niche on LI appeared to be even more diversified because of the presence of several disturbances to which populations seem to respond by the increase of juveniles and showing a more reliance on the regeneration niche. Concerning the niche breadth, at the regional scale wider niche were observed on LI, probably for the high spatial heterogeneity, which was positively correlated to island size. In contrast, at the local scale, SI showed a wider niche breadth which appears to be due to a release from competition.

Styles APA, Harvard, Vancouver, ISO, etc.

Cipollini, Elena <1975&gt. « Cystatin B and its EPM1 mutants are polymeric and aggregate prone in vivo ». Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2007. http://amsdottorato.unibo.it/405/1/CipolliniElena.pdf.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Fidelis, Natasha Siqueira. « Avaliação da reação tecidual frente aos cimentos MTA Branco Angelus®, MTA Bio e Sealepox RP : estudo microscópico em tecido subcutâneo de ratos ». Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/25/25138/tde-02072009-103945/.

Texte intégral

Résumé :

Biocompatibilidade é uma das principais propriedades que um cimento retrobturador deve possuir, para não provocar no hospedeiro reações tóxica e imunopatológica. Desta forma, a sucessão de experimentos que comprovem tal propriedade, é fundamental para o uso clínico desse material. O objetivo deste estudo foi comparar a reação tecidual frente ao MTA Branco Angelus®, MTA Bio Ângelus® e Sealepox RP. Para isso, foram utilizados 54 ratos Wistar albinos, que foram divididos em 3 grupos iguais. Os materiais foram implantados no tecido subcutâneo do dorso desses animais, dentro de tubos de polietileno. Como controle, todos os tubos tiveram uma de suas extremidades seladas com guta-percha. Os períodos experimentais analisados foram de 15, 30 e 60 dias após o procedimento cirúrgico, quando, então, os animais foram mortos. As amostras coletadas passaram pelo processamento histotécnico e foram feitos cortes de 5µm de espessura e coloração com hematoxilina e eosina. Os dados obtidos após a análise morfométrica foram submetidos à análise de variância a dois critérios (ANOVA) e teste de Kruskal-Wallis para comparação; a significância foi para p<0,05. Os resultados demonstraram que em todos os grupos e períodos houve um padrão de comportamento da reação inflamatória, ou seja, aos 15 dias havia uma densidade de volume de células inflamatórias maior, que foi decrescendo com o passar do tempo. Não houve diferença estatisticamente significante entre os materiais com relação a densidade de volume de células inflamatórias observadas. Com base na metodologia empregada e levando em conta suas limitações, pode-se concluir que todos os materiais testados são biocompatíveis.
Biocompatibility is one of the most important properties that a root-end filling material might have. Thus, experiments that prove this characteristic are very important. The purpose of this study was to compare the connective tissue reaction caused by MTA White Angelus, MTA Bio and Sealepox RP. Fifty-four Wistar albino rats were divided in three equal groups. The materials were implanted in subcutaneous connective tissue of the animals, into polyethylene tubes. As control group, gutta-percha was placed in one of the tubes border. The rats were sacrificed after 15, 30 and 60 days. Histologic samples were sectioned in 5µm thickness and stained with hematoxylin and eosin. ANOVA and Kruskal-Wallis tests were used for statistical analysis (p<0,05). The results showed that in all groups there was a standard result on the inflammatory infiltrate observed. The 15 days period showed a more severe response, which has been diminishing over time. There was no statistically significant difference between the materials with respect to the volume density of inflammatory cells observed. Based on the methodology used and taking into account its limitations, it can be concluded that all materials are biocompatible.

Styles APA, Harvard, Vancouver, ISO, etc.

Livres sur le sujet "Bio-aggregate"

Amziane, Sofiane, Laurent Arnaud et Noël Challamel, dir. Bio-aggregate-based Building Materials. Hoboken, NJ 07030 USA : John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118576809.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Arnaud, Laurent, et S. Amziane. Bio-Aggregate-Based Building Materials : Applications to Hemp Concretes. Wiley & Sons, Incorporated, John, 2013.

Trouver le texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Arnaud, Laurent, et Sofiane Amziane. Bio-Aggregate-based Building Materials : Applications to Hemp Concretes. Wiley & Sons, Incorporated, John, 2013.

Trouver le texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Arnaud, Laurent, et Sofiane Amziane. Bio-Aggregate-based Building Materials : Applications to Hemp Concretes. Wiley & Sons, Limited, John, 2013.

Trouver le texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Arnaud, Laurent, et Sofiane Amziane. Bio-Aggregate-based Building Materials : Applications to Hemp Concretes. Wiley & Sons, Incorporated, John, 2013.

Trouver le texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Arnaud, Laurent, et Sofiane Amziane. Bio-Aggregate-based Building Materials : Applications to Hemp Concretes. Wiley & Sons, Incorporated, John, 2013.

Trouver le texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Chapitres de livres sur le sujet "Bio-aggregate"

Nozahic, Vincent, et Sofiane Amziane. « Environmental, Economic and Social Context of Agro-Concretes ». Dans Bio-aggregate-based Building Materials, 1–26. Hoboken, NJ 07030 USA : John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118576809.ch1.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Picandet, Vincent. « Characterization of Plant-Based Aggregates ». Dans Bio-aggregate-based Building Materials, 27–74. Hoboken, NJ 07030 USA : John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118576809.ch2.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Escadeillas, Gilles, Camille Magniont, Sofiane Amziane et Vincent Nozahic. « Binders ». Dans Bio-aggregate-based Building Materials, 75–116. Hoboken, NJ 07030 USA : John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118576809.ch3.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Lanos, Christophe, Florence Collet, Gérard Lenain et Yves Hustache. « Formulation and Implementation ». Dans Bio-aggregate-based Building Materials, 117–52. Hoboken, NJ 07030 USA : John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118576809.ch4.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Arnaud, Laurent, Sofiane Amziane, Vincent Nozahic et Etiennec Gourlay. « Mechanical Behavior ». Dans Bio-aggregate-based Building Materials, 153–78. Hoboken, NJ 07030 USA : John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118576809.ch5.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Arnaud, Laurent, Driss Samri et Étienne Gourlay. « Hygrothermal Behavior of Hempcrete ». Dans Bio-aggregate-based Building Materials, 179–242. Hoboken, NJ 07030 USA : John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118576809.ch6.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Glé, Philippe, Emmanuel Gourdon et Laurent Arnaud. « Acoustical Properties of Hemp Concretes ». Dans Bio-aggregate-based Building Materials, 243–66. Hoboken, NJ 07030 USA : John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118576809.ch7.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Munoz, Philippe, et Didier Pipet. « Plant-Based Concretes in Structures : Structural Aspect - Addition of a Wooden Support to Absorb the Strain ». Dans Bio-aggregate-based Building Materials, 267–88. Hoboken, NJ 07030 USA : John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118576809.ch8.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Boutin, Marie-Pierre, et Cyril Flamin. « Examination of the Environmental Characteristics of a Banked Hempcrete Wall on a Wooden Skeleton, by Lifecycle Analysis : Feedback on the LCA Experiment from 2005 ». Dans Bio-aggregate-based Building Materials, 289–312. Hoboken, NJ 07030 USA : John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118576809.ch9.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Lanos, Christophe. « Bio-aggregate Based Building Materials Exposed to Fire ». Dans Bio-aggregates Based Building Materials, 149–65. Dordrecht : Springer Netherlands, 2017. http://dx.doi.org/10.1007/978-94-024-1031-0_7.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Actes de conférences sur le sujet "Bio-aggregate"

Lo Presti, Nicolò, Kamilia Abahri, Giovanni Castellazzi, Paolo Mengoli et Paolo Stabellini. « Experimental Investigation of Lightweight Mortars Based on Recycled Olive Kernel through Hygric and Mechanical Characterization ». Dans 2024 10th International Conference on Architecture, Materials and Construction & 2024 5th International Conference on Building Science, Technology and Sustainability, 27–32. Switzerland : Trans Tech Publications Ltd, 2025. https://doi.org/10.4028/p-z8fxbr.

Texte intégral

Résumé :

Bio-based building materials are now being widely explored by researchers to promote their effective use and reduce the environmental impact of building construction. Among these, mortars based on olive kernel aggregate, a waste product of the production of olive oil, can be effectively adopted for moderate load-bearing applications in buildings thanks to their lower density and thermal conductivity,compared to traditional sand-based mortars. Nevertheless, to date most of the researchers focused on mortars produced with a partial substitution of traditional sand with olive kernels and relatively high dosages of binder. In this work, mortars entirely based on olive kernel aggregate were produced employing limited dosages of binder. Mechanical, hygric properties and the density were evaluated on the hardened materials for different tested formulations. Results showed a high dependency of mechanical properties on the dosage of binder and demonstrated their employability for moderate load-bearing applications in buildings.

Styles APA, Harvard, Vancouver, ISO, etc.

Ratsimbazafy, Herinjaka Haga, Aurélie Laborel-Préneron, Camille Magniont et Philippe Evon. « Comprehensive Characterization of Agricultural By-Products for Bio-Aggregate Based Concrete ». Dans 4th International Conference on Bio-Based Building Materials. Switzerland : Trans Tech Publications Ltd, 2022. http://dx.doi.org/10.4028/www.scientific.net/cta.1.77.

Texte intégral

Résumé :

The valorization of available agricultural by-products is important for the development of bio-aggregate based concretes as eco-friendly solutions for building materials. However, their diversity requires to assess their potential of use in vegetal concretes. This study aims to propose simple and relevant multi-physical characterization methods for plant aggregates. Basic and complementary characterizations were carried out on hemp shiv as a reference plant aggregate, and nine by-products available in the South-West part of France, i.e., oleaginous flax shiv, sunflower pith and bark, coriander straw, wheat straw, wheat chaff, corn shuck, miscanthus stem and vine shoot. The basic characterizations performed were those recommended by the TC-RILEM 236 BBM, i.e., particle size distribution, bulk density, water absorption and thermal conductivity. Complementary characterizations have also been proposed, taking into account the possible environment of the binder and the vegetal concrete manufacturing method. The additional tests developed or adapted from previous research assess the following properties: the content of water-soluble compounds at pH 7 and 12, the dry density of plant aggregates compacted in wet state, the real water absorption after compaction and the compression behavior of these compacted aggregates. This complete characterization highlights the distinct behavior of the different agroresources and allows to correlate these characteristics to the use properties of hardened composites.

Styles APA, Harvard, Vancouver, ISO, etc.

Poluektova, Valentina Anatolyevna, Valentina Dmitryevna Mukhacheva et Julia Vladimirovna Denisova. « Polyfunctional modifier for bio-corrosion resistant high-performance fine-aggregate concretes ». Dans International Conference "Actual Issues of Mechanical Engineering" 2017 (AIME 2017). Paris, France : Atlantis Press, 2017. http://dx.doi.org/10.2991/aime-17.2017.101.

Texte intégral

Styles APA, Harvard, Vancouver, ISO, etc.

Ntimugura, Fabrice, Raffaele Vinai, Anna Harper et Pete Walker. « Experimental Investigation on Mechanical and Acoustic Performance of Miscanthus - Lime Composites ». Dans 4th International Conference on Bio-Based Building Materials. Switzerland : Trans Tech Publications Ltd, 2022. http://dx.doi.org/10.4028/www.scientific.net/cta.1.12.

Texte intégral

Résumé :

The environmental burdens attributable to buildings remain relatively high. The built environment is responsible for more than one-third of the global energy consumption and nearly 40% of global CO2 emissions. In the context of increasing the sustainability of the built environment, bio-based building materials have gained a growing interest for their application in building envelopes. Miscanthus giganteus (elephant grass) is a perennial, cost effective and sustainable source of fibres for the development of bio-composites. This experimental study evaluates mechanical and acoustic properties of miscanthus - lime composites for their potential use in renovations and new-build houses, in South West England. The impact of binder to aggregate mass ratio and density on compressive strength is investigated. Moreover, the effect of aggregate particle size on the acoustic performance of miscanthus - lime composites is presented. It is shown that the initial fresh density has little effect on compressive strength compared with that of binder content. The acoustic tests results show that the use of small size particles improves the acoustic performance of miscanthus - lime composites with recorded high transmission loss and sound absorption coefficient values.

Styles APA, Harvard, Vancouver, ISO, etc.

El Moussi, Youssef, Laurent Clerc et Jean-Charles Benezet. « Study of the Impact of Rice Straw Particle Size on the Mechanical and Thermal Properties of Straw Lime Concretes ». Dans 4th International Conference on Bio-Based Building Materials. Switzerland : Trans Tech Publications Ltd, 2022. http://dx.doi.org/10.4028/www.scientific.net/cta.1.361.

Texte intégral

Résumé :

The use of bio-based concretes performed with lignocellulosic aggregates constitute an interesting solution for reducing the energy consumption, greenhouse gas emissions and CO2 generated by the building sector. Indeed, bio-based materials could be used as an alternative of traditional materials such as expended polystyrene and mineral resources (e.g. glass and rock wools) for insulation. Furthermore, these bio-based concretes are known for their interesting insulation properties, indeed they allow to enhance thermal properties of buildings and enables moisture management which lead to design efficient building materials. For this purpose, bio-based concrete using rice straw as aggregate are studied in this present work. The impact of the characteristics of rice straw particle (particle size distribution, bulk density, and water absorption capacity, etc.) on both the mechanical and thermal properties of the bio-based concrete are investigated. Five formulations of rice straw concrete are examined, compared and then classified in terms of insulation properties and mechanical properties. The assessments are based on the measurement of density and thermal conductivity. The variation of compressive strength in function of the characteristics (mean particle length) of rice straw particle are assessed and discussed. The investigation covers also the porosity and density. Tests are also carried out on agricultural by-products with a view to highlight their chemical, physical and structural proprieties. The results show that the use of large particles with low water absorption capacity induce lighter concretes with the density between 339 and 505 kg/m3 and lead to a high compressive strength with a high mechanical deformability. Furthermore, it appears that an increase in the average length of rice straw particle lead to decrease of thermal conductivity of bio-based concretes. It varies from 0.062 to 0.085 W/(m.K).

Styles APA, Harvard, Vancouver, ISO, etc.

Meshram, Pawan Devidas, L. Natrayan, N. Balaji et Vinay Reddy. « Investigation of Mechanical and Thermal Properties of Bamboo Fiber Reinforced with Epoxidized Soybean Oil for Automotive Seat Bases ». Dans Automotive Technical Papers. 400 Commonwealth Drive, Warrendale, PA, United States : SAE International, 2024. http://dx.doi.org/10.4271/2024-01-5009.

Texte intégral

Résumé :

<div class="section abstract"><div class="htmlview paragraph">Bamboo fibers were used as reinforcement in hardened epoxy mixes altered with ethoxylated soybean oil (ESO) to enhance the mechanical and thermal qualities. Compared to a bio-based epoxy mix, the tensile strength and modulus of the laminate with 20% bamboo fiber were higher. During thermogravity analysis (TGA) evaluation, it was discovered that the rate of deterioration peak had been moved to a warmer temperature, indicating improved thermal durability of the aggregate over the base material. The dynamic mechanical evaluation of the bio-based composite anticipated increased storage modulus and greater glass transition temperatures. High fiber–matrix adherence was visible in scanning electron morphology (SEM). Measurements of the interfacial adhesion demonstrate the hydrophilicity of the bio-based reinforced composites. The binding and effective insemination of fibers is responsible for the fiber-reinforced composite’s durability. Higher rigidity and durability were generated because the lignocellulosic biomass adhered well to the low-viscosity resin. Moreover, research on adherence in composite materials reveals that the interfaces of composite materials with bamboo fibers are becoming more hydrophilic. Sufficient mechanical hardness, stiffness, and durability are realized for automobile and industrial purposes.</div></div>

Styles APA, Harvard, Vancouver, ISO, etc.

Ding, Houzhu, et Robert C. Chang. « Bioprinting of Liquid Hydrogel Precursors in a Support Bath by Analyzing Two Key Features : Cell Distribution and Shape Fidelity ». Dans ASME 2018 13th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/msec2018-6675.

Texte intégral

Résumé :

Microextrusion-based bioprinting within a support bath material is an emerging additive manufacturing technique for fabricating complex three-dimensional (3D) tissue constructs. However, there exists fundamental knowledge gaps in understanding the spatiotemporal mapping of cells within the bioprinted constructs and their shape fidelity when embedded in a support bath material. To address these questions, this paper advances quantitative analyses to systematically determine the spatial distribution for cell-laden filament-based tissue constructs as a function of the bio-ink properties. Also, optimal bio-ink formulations are investigated to fabricate complex 3D structures with superior shape integrity. Specifically, for a 1D filament printed in a support bath, cells suspended in low viscosity liquid hydrogel precursors are found to exhibit a characteristic non-uniform distribution as measured by a degree of separation (Ds) metric. In a 2D square wave pattern print, cells are observed to flow and aggregate downstream at certain positions along the in-plane print direction. In a 3D analysis, owing to the high cell density and gravity effects, a non-uniform cell distribution within a printed cylindrical structure is observed in the build direction. From the structural standpoint, the addition of CaCl2 to the support bath activates the hydrogel cross-linking process during printing, resulting in 3D prints with enhanced structural outcomes. This multidimensional print analysis provides evidence that, under the emerging bioprinting support bath paradigm, the printable parameter space can be extended to low viscosity liquid hydrogel precursor materials that can be systematically characterized and optimized for key process performance outcomes in cell distribution and shape fidelity.

Styles APA, Harvard, Vancouver, ISO, etc.

Burra, K. G., et A. K. Gupta. « Characteristics of Char From Co-Pyrolysis of Biomass and Plastic Waste ». Dans ASME 2018 Power Conference collocated with the ASME 2018 12th International Conference on Energy Sustainability and the ASME 2018 Nuclear Forum. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/power2018-7255.

Texte intégral

Résumé :

Development of alternative, clean and renewable energy production from different hydrocarbon materials helps to partially replace the limited resources of fossil fuels and also help reduce carbon emissions from fossil fuels that drives global warming. Biomass and bio-wastes are renewable and sustainable hydrocarbon resources, which can be used for energy and fuels production along with permanent disposal of plastic wastes. Landfills of wastes is unsustainable with additional problems of non-degradability and growing burden to the environment and society. Co-pyrolysis and co-gasification of biomass with different types of plastic wastes has shown to provide enhanced product yields and quality for syngas and liquid fuel production. To date, limited information is available on the understanding of chars produced from co-pyrolysis. The effect of co-pyrolysis on the type, quality and yield of chars produced is essential for efficient utilization of a wide variety of biomass, bio-waste and plastic waste resources. This paper provides information on the effect of plastic addition to the pyrolysis of biomass as well as the quality and quantity of char produced with different amounts of plastic waste added at different pyrolysis temperatures. TGA reactor was used for all these investigations and the quality of char produced was examined from the perspective of char combustion for energy production. Char is commonly produced as a by-product from pyrolysis and gasification reactors. Carbonization temperatures investigated were in the range of 573–773 K for 30 min using pinewood biomass, while recycled polyethylene terephthalate was used as plastic waste. The investigations revealed that chars produced from co-pyrolysis especially for carbonization temperature (Tc) of 673 K and above behaved completely differently than the chars produced from separate pyrolysis of biomass and plastic waste under the same pyrolysis conditions. These chars produced from co-pyrolysis were more uniform in their behavior in oxidation environment, with higher heat flow for almost similar quantities of chars during oxidation. This was conjectured to be from enhanced quality of chars produced having increased C content (from increased heavy aromatics and efficient loss of volatiles) during co-pyrolysis without any loss of char yield. The char yield was found to be equal or higher during co-pyrolysis compared to the weighted aggregate of individual pyrolysis. These investigations provided novel results on the behavior and capabilities of chars produced from co-pyrolysis of biomass and plastic wastes to provide a new avenue for the quality enhancement of bio-chars and efficient utilization of carbonaceous solid waste resources.

Styles APA, Harvard, Vancouver, ISO, etc.

Kwon, Jae-Sung, Sandeep Ravindranath, Aloke Kumar, Joseph Irudayaraj et Steven T. Wereley. « Application of an Optically Induced Electrokinetic Manipulation Technique on Live Bacteria ». Dans ASME 2010 International Mechanical Engineering Congress and Exposition. ASMEDC, 2010. http://dx.doi.org/10.1115/imece2010-39324.

Texte intégral

Résumé :

In this paper, we apply a recently demonstrated rapid electrokinetic patterning (REP) technique to Shewanella oneidensis MR-1 and confirm the application possibility of the technique on bio-materials. This technique utilizes a simple microfluidic chip with two indium tin oxide (ITO) coated parallel electrodes and requires the simultaneous application of AC electric field and the hologram provided from an infrared (1064 nm) laser, in order to control and aggregate particles onto electrodes. For the experimentation in this paper, Shewanella oneidensis MR-1 are cultured by green fluorescent protein (GFP) on Luria-Bertani (LB) agar plate and through sample pretreatment process, mid-log phase samples of the bacteria finally are obtained. As a result of applying REP technique to this bacteria sample, we could collect a lot of the bacteria onto ITO electrode surfaces rapidly and the bacteria cluster could be translated with the movement of laser focus position under uniform electric field. Also it was confirmed that there exists a particular frequency range, i.e. critical frequency for REP based bacteria cluster. We could find that under the application of REP technique, the ellipsoidal bacteria are reoriented with respect to electric field lines as electrical frequency increases up. Also the change in the vertical distance between the bacteria and the electrode surface with electrical voltages could be observed. These results show that the REP technique can be used to separate, sort and manipulate bioparticles like bacteria.

Styles APA, Harvard, Vancouver, ISO, etc.

Ding, Houzhu, Enyan Dai, Filippos Tourlomousis et Robert C. Chang. « A Methodology for Quantifying Cell Density and Distribution in Multidimensional Bioprinted Gelatin-Alginate Constructs ». Dans ASME 2017 12th International Manufacturing Science and Engineering Conference collocated with the JSME/ASME 2017 6th International Conference on Materials and Processing. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/msec2017-2853.

Texte intégral

Résumé :

Bioprinted tissue constructs are enabled by microextrusion-based co-printing of cells and hydrogel materials. In this paper, a gelatin-alginate hydrogel material formulation is implemented as the bio-ink towards a 3D cell-laden tissue construct. However, of fundamental importance during the printing process is the interplay between the various parameters that yield the final cell distribution and cell density at different dimensional scales. To investigate these effects, this study advances a multidimensional analytical framework to determine the spatial variations and temporal evolution of cell distribution and cell density within a bioprinted cell-laden construct. In the one dimensional (1D) analysis, the cell distribution and cross-sectional shape for a single printed fiber are observed to be dependent on the process temperature and material concentration parameters. This is illustrated by the reliable fabrication and image line profile analysis of the fiber prints. Round fiber prints with a measured width of 809.5±52.3 μm maintain dispersive cells with a degree of dispersion (Dd) at 96.8 % that can be achieved at high relative material viscosities under low temperature conditions (21 °C) or high material concentrations (10 % w/v gelatin). On the other hand, flat fiber prints with a measured width of 1102.2±63.6 μm coalesce cells towards the fiber midline with Dd = 76.3% that can be fabricated at low relative material viscosities under high temperature (24 °C) or low material concentrations (7.5 % w/v gelatin). In the 2D analysis, a printed grid structure yields differential cell distribution whereby differences in localized cell densities are observed between the strut and cross regions within the printed structure. At low relative viscosities, cells aggregate at the cross regions where two overlapping filaments fuse together, yielding a cell density ratio of 2.06±0.44 between the cross region and strut region. However, at high relative viscosities, the cell density ratio decreases to 0.96±0.03. In the 3D analysis, the cell density attributed to the different layers is studied as a function of printing time elapsed from the initial bio-ink formulation. Due to identifiable gravity and extrusion process-induced effects, the cell distribution within the original bio-ink cartridge or material reservoir is altered over time to yield initial quantitative increases in the cell density over the first several printed layers, followed by quantitative decreases in the subsequent printed layers. Finally, in the time-dependent analysis, the evolution of cell density and the emergence of material degradation effects is studied over a time course study. Variable initial cell densities (0.6 × 106 cells/ml, 1.0 × 106 cells/ml, and acellular control group) printed and cross-linked into cell-laden constructs for the 48 hr time course study exhibit a time-dependent increase in cell density owing to proliferation within the constructs that are presumed to accelerate the degradation rate.

Styles APA, Harvard, Vancouver, ISO, etc.

Nous offrons des réductions sur tous les plans premium pour les auteurs dont les œuvres sont incluses dans des sélections littéraires thématiques. Contactez-nous pour obtenir un code promo unique!