Journal articles on the topic 'Extrusion aggregate'
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Rushing, Todd S., Ghassan Al-Chaar, Brian Andrew Eick, Jedadiah Burroughs, Jameson Shannon, Lynette Barna, and Michael Case. "Investigation of concrete mixtures for additive construction." Rapid Prototyping Journal 23, no. 1 (January 16, 2017): 74–80. http://dx.doi.org/10.1108/rpj-09-2015-0124.
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Purpose This paper aims to qualify traditional concrete mixtures for large-scale material extrusion in an automated, additive manufacturing process or additive construction. Design/methodology/approach A robust and viable automated additive construction process must be developed that has the capability to construct full-scale, habitable structures using materials that are readily available near the location of the construction site. Accordingly, the applicability of conventional concrete mixtures for large-scale material extrusion in an additive construction process was investigated. A qualitative test was proposed in which concrete mixtures were forced through a modified clay extruder and evaluated on performance and potential to be suitable for nozzle extrusion typical of additive construction, or 3D printing with concrete. The concrete mixtures were further subjected to the standard drop table test for flow, and the results for the two tests were compared. Finally, the concrete mixtures were tested for setting time, compressive strength and flexural strength as final indicators for usefulness in large-scale construction. Findings Conventional concrete mixtures, typically with a high percentage of coarse aggregate, were found to be unsuitable for additive construction application due to clogging in the extruder. However, reducing the amount of coarse aggregate provided concrete mixtures that were promising for additive construction while still using materials that are generally available worldwide. Originality/value Much of the work performed in additive manufacturing processes on a construction scale using concrete focuses on unconventional concrete mixtures using synthetic aggregates or no coarse aggregate at all. This paper shows that a concrete mixture using conventional materials can be suitable for material extrusion in additive construction. The use of conventional materials will reduce costs and allow for additive construction to be used worldwide.
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Demiriz, Levent, and EbruHazar Bodrumlu. "Severe unintentional extrusion of mineral trioxide aggregate during apexification." Indian Journal of Dental Research 28, no. 3 (2017): 341. http://dx.doi.org/10.4103/ijdr.ijdr_365_16.
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MORI, AKIKO, and YASUNORI MATSUFUJI. "INFLUENCES OF FINE AGGREGATE GEOMETRY ON EXTRUSION CHARACTERISTICS OF MORTARS." Journal of Structural and Construction Engineering (Transactions of AIJ) 397 (1989): 12–18. http://dx.doi.org/10.3130/aijsx.397.0_12.
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El Cheikh, K., S. Rémond, N. Khalil, and G. Aouad. "Numerical and experimental studies of aggregate blocking in mortar extrusion." Construction and Building Materials 145 (August 2017): 452–63. http://dx.doi.org/10.1016/j.conbuildmat.2017.04.032.
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Demiriz, Levent, and Ebru Hazar Bodrumlu. "Retrospective Evaluation of Healing of Periapical Lesions after Unintentional Extrusion of Mineral Trioxide Aggregate." Journal of Applied Biomaterials & Functional Materials 15, no. 4 (January 2017): e382-e386. http://dx.doi.org/10.5301/jabfm.5000359.
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Background During the apexification procedure for teeth with open apices, mineral trioxide aggregate (MTA) may be unintentionally extruded. The aim of the present study was the retrospective evaluation of the healing of periapical lesions in permanent incisor teeth with open apices after the unintentional extrusion of MTA. Methods The clinical and radiographic records of 55 maxillary permanent central teeth treated by MTA apexification were evaluated. Filled teeth with unintentionally extruded MTA were selected as group 1 (n = 21), whereas the teeth with no MTA extrusion were selected as group 2 (n = 34). For each tooth, the clinical and radiographic records from a 3-year follow-up were investigated. Results Complete healing (CH) was observed in 19 teeth (90.4%) in group 1, whereas the same type of healing was observed in all 34 teeth (100%) in group 2 (p>0.05). At the 6-month follow-up appointment, 25 teeth (73.5%) showed CH in group 2, whereas 15 teeth (71.4%) showed CH at the 1-year follow-up in group 1 (p<0.001). At the end of the 3-year follow-up period, the amount of MTA extrusion was reduced in 17 teeth (85%) (p<0.05), whereas it was almost absent in 2 teeth (10%). Conclusions The unintentional extrusion of MTA does not prevent the healing of periapical lesions, but may be a delaying factor for periapical healing.
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Bartnicki, J. "Numerical Analysis of Rolling Extrusion Process of a Hollow Hub / Analiza Numeryczna Procesu Przepychania Obrotowego Piasty Drążonej." Archives of Metallurgy and Materials 57, no. 4 (December 1, 2012): 1137–42. http://dx.doi.org/10.2478/v10172-012-0127-z.
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This paper presents the results of numerical calculations of rolling extrusion process of a hollow hub. Simulations were made by means of software Deform 3D in three dimensional state of strain. Distributions of effective stress, effective strain and damage criterion in the rolled extruded product were analyzed. Verification of metal flow during process allowed to design tools for experimental verification in PO-2 laboratory rolling - extrusion aggregate. For these needs also process force parameters were calculated.
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Watanabe, Ikumu. "Two-Scale Finite Element Analysis of Equaled Channeling Angular Extrusion of Polycrystalline Metal." Materials Science Forum 783-786 (May 2014): 2713–19. http://dx.doi.org/10.4028/www.scientific.net/msf.783-786.2713.
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A two-scale finite element analysis method based on a micro-macro decoupled scheme is applied to an equaled channeling angular extrusion. At first, the macro-scale finite element analysis for one process of an equaled channeling angular extrusion is carried out with a non-liner explicit method to handle the contact and friction between die and bullet. Using the deformation history at a macroscopic material point in this process, the micro-scale finite element analysis is conducted for the multiple processes with a single crystal plasticity and a nonlinear implicit method. As the results, the deformation process of the polycrystalline aggregate during the equaled channeling angular extrusion is numerically reproduced.
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Nosrat, A., M. H. Nekoofar, B. Bolhari, and P. M. H. Dummer. "Unintentional extrusion of mineral trioxide aggregate: a report of three cases." International Endodontic Journal 45, no. 12 (June 30, 2012): 1165–76. http://dx.doi.org/10.1111/j.1365-2591.2012.02082.x.
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Bartnicki, Jarosław. "Numerical Analysis of Feed Rate Influence on Hollow Hub Shape during Rolling Extrusion Process." Key Engineering Materials 572 (September 2013): 323–26. http://dx.doi.org/10.4028/www.scientific.net/kem.572.323.
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This paper presents the results of numerical calculations of rolling extrusion process of a hollow hub. Due to the necessity of flanges manufacturing at both sides of the product, in the analyzed process of rolling extrusion, as additional tool limiting axial metal flow a rear bumper was implemented [1,. Numerical calculations of the hub forming process were conducted basing on finite element method, applying software Deform3D v.X in conditions of three dimensional state of strain. The obtained small shape faults, in the form of characteristic triangulation and small changes of the hub walls thickness, show that it is possible to conduct the further research works of experimental character, with the application of modernized aggregate for the rolling extrusion process PO-2.
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Volpe, Stelladriana, Andrea Petrella, Valentino Sangiorgio, Michele Notarnicola, and Francesco Fiorito. "Preparation and characterization of novel environmentally sustainable mortars based on magnesium potassium phosphate cement for additive manufacturing." AIMS Materials Science 8, no. 4 (2021): 640–58. http://dx.doi.org/10.3934/matersci.2021039.
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<abstract> <p>The "Digital Transition" of the building sector and in particular the concrete 3D printing is profoundly changing building technologies and construction processes. However, the materials engineering is still a challenge for the research of even more effective and performing 3D printable concrete. In this context, we analysed magnesium potassium phosphate cement (MKPC) performance as an innovative cementitious material in terms of sustainability and possibility of its use in extrusion-based 3D concrete printing (3DPC). Starting from common formulations present in literature, we discussed the relationship between water to binder ratio and workability in two different quantities of retarders. Some mix compositions were also prepared by replacing sand with rubber aggregates or glass aggregates with the aim of creating lightweight aggregate-based mortars. In addition, the fly ash (FA), a widely material used (but that will not be available in the next few years), was replaced with silica fume (SF). We found that two formulations (samples 2 and 7) show rheological requirements and compressive strengths at 90 min of respectively about 2 MPa and 3 MPa, which are deemed to be suitable for 3D printing processes. Moreover, in sample 7, the use of the expanded recycled glass as aggregate opens new possibilities for reducing the carbon footprint of the process.</p> </abstract>
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Xiaoxiang, Zhang, He Jianxin, Wei Peng, Huang Xin, Tian Huimin, and Chen Min. "Preparation and Properties of Nylon 6,6 Grafted Graphene Composites." Journal of Nanoscience and Nanotechnology 20, no. 3 (March 1, 2020): 1977–82. http://dx.doi.org/10.1166/jnn.2020.17347.
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Nylon 6,6 composite fiber containing grafted graphene (nylon 6,6-g-graphene) was prepared by nylon and graphene grafted with acyl chloride (graphene-COCl) through extrusion reaction. Graphene-COCl was prepared through acid-treated reacting, graphene with thionyl chloride functional group. The chemical structure of nylon 6,6-g-graphene obtained using reactive extrusion technique was characterized using Fourier transform infrared spectrometer. It was found that this kind of composite fiber has the characteristics of less amount of graphene and excellent mechanical properties and has certain application prospects. Nylon 6,6-g-graphene dispersed evenly in the Nylon composite. But pristine graphene exhibited aggregate structure when composite was produced by pristine graphene through reactive extrusion. The composite reinforcement was increased obviously with the increase content of grafted graphene. After examined, the nylon/nylon 6,6-g-graphene with a certain content grafted graphene composite exhibited high level of reinforcement, and mechanical properties were improved.
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Tezel, Bahar, Serdar Uysal, Melek Turgut, and Zafer Cehreli. "Inadvertent MTA Extrusion in an Immature Traumatized Permanent Incisor." Journal of Clinical Pediatric Dentistry 35, no. 2 (December 1, 2010): 145–48. http://dx.doi.org/10.17796/jcpd.35.2.92855564728x0mxq.
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This report describes the 24-month clinical and radiographic outcome of an unintentionally extruded mineral trioxide aggregate (MTA) apical plug. A 9 year old boy presented with a previously traumatized, immature central incisor; associated with a large periradicular lesion. During placement of MTA in the treatment of wide open apex, the material was inadvertently extruded into the periapical region upon a sudden movement of the child. No intervention was made, except for obturation of the remaining root canal two weeks later. The radiographic follow up at 12 and 24 months confirmed successful management through the non surgical approach, as evidenced by advanced healing of the periapical lesion and regeneration of the periradicular tissue in the absence of clinical symptoms.
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Nagmode, Pradnya S., Archana B. Satpute, Ankit V. Patel, and Pushpak L. Ladhe. "The Effect of Mineral Trioxide Aggregate on the Periapical Tissues after Unintentional Extrusion beyond the Apical Foramen." Case Reports in Dentistry 2016 (2016): 1–5. http://dx.doi.org/10.1155/2016/3590680.
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Introduction. Single-step apexification procedures using mineral trioxide aggregate (MTA) have been reported as favorable treatment options for teeth with an open apex, posing greater benefits compared to the other available medicaments. However, controlled apical placement of MTA is a challenging procedure to perform using orthograde approach. This case series describes the outcome of the unintentional extrusion of MTA into periradicular tissues during apexification, in three separate cases.Methods. Three adult patients reported to the Department of Conservative Dentistry and Endodontics for the management of maxillary incisors with open apices. After isolation, conventional access, and cleaning and shaping procedures, one-step MTA apexification was performed. On subsequent radiographs, a considerable amount of MTA was seen to be extruded in all the three cases.Results. During follow-up examination the teeth were seen to be asymptomatic in all cases and radiographically demonstrated repair of the periapical lesion.Conclusion. The results of these cases suggest that extrusion of MTA into the periapical tissues does not cause any detrimental effect, which could be attributed to the biologic properties of MTA.
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Bing, Li, Zhou Nan Qiao, Zhang Zhi Hong, and Luo Wei Hua. "Study on Mechanical Properties and Molecular Aggregate of the Dynamic Extrusion Polymer Filling System." Polymer-Plastics Technology and Engineering 46, no. 3 (March 8, 2007): 293–98. http://dx.doi.org/10.1080/03602550601155724.
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MORI, Akiko, and Akio BABA. "EFFECTS OF AGGREGATE SIZE ON PROCESS CONTROL OF PRODUCING CEMENTITIOUS MATERIALS UNDER EXTRUSION MOULDING." Journal of Structural and Construction Engineering (Transactions of AIJ) 62, no. 491 (1997): 1–7. http://dx.doi.org/10.3130/aijs.62.1_1.
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Chen, Yidong, Yunsheng Zhang, Bo Pang, Zhiyong Liu, and Guojian Liu. "Extrusion-based 3D printing concrete with coarse aggregate: Printability and direction-dependent mechanical performance." Construction and Building Materials 296 (August 2021): 123624. http://dx.doi.org/10.1016/j.conbuildmat.2021.123624.
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Lee, Ho Won, Young Seon Lee, and Seong Hoon Kang. "Microstructure Prediction during Hot Deformation Using New Dynamic Recrystallization Model and Finite Element Analysis." Key Engineering Materials 611-612 (May 2014): 483–88. http://dx.doi.org/10.4028/www.scientific.net/kem.611-612.483.
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In this study, dynamic recrystallization during nonisothermal hot deformation was numerically simulated by finite element analysis and new physically based dynamic recrystallization model. The dynamic recrystallization model was developed based on mean field approach by assuming grain aggregate as representative volume element. For each grain aggregate, changes of state variables such as dislocation density and grain size were calculated using three sub-models for work hardening, nucleation, and nucleus growth. The developed dynamic recrystallization model was validated by comparing with isothermal hot compression of pure copper. Finally, developed dynamic recrystallization model was combined with finite element method to predict the local changes of microstructure and average grain size during nonisothermal hot compression of pure copper and hot tube extrusion of austenitic stainless steel. The simulation results were in reasonably good agreement with experimentally determined microstructures.
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Bodhwani, Mohit A. "Mineral Trioxide Aggregate Apexification in a Nonvital Immature Central Incisor Tooth using an Internal Matrix." Journal of Contemporary Dentistry 4, no. 2 (2014): 113–17. http://dx.doi.org/10.5005/jp-journals-10031-1079.
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ABSTRACT Apexification is a method to induce a calcified barrier in a root with an open apex or the continued apical development of an incomplete root in teeth with necrotic pulp. Mineral trioxide aggregate (MTA) has shown immense potential as an apical plug to induce apexification. It is better than the traditionally used calcium hydroxide as it completes the procedure more quickly and effectively. The following case report stresses on the need of an internal matrix to avoid unwanted extrusion of MTA in the periapical tissues. The internal matrix used in this case report is calcium hydroxide. How to cite this article Bodhwani MA, Shenoy VU, Sumanthini MV. Mineral Trioxide Aggregate Apexification in a Nonvital Immature Central Incisor Tooth using an Internal Matrix. J Contemp Dent 2014;4(2):113-117.
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Cooper, Jason F., Ryan J. Guasp, Meghan Lee Arnold, Barth D. Grant, and Monica Driscoll. "Stress increases in exopher-mediated neuronal extrusion require lipid biosynthesis, FGF, and EGF RAS/MAPK signaling." Proceedings of the National Academy of Sciences 118, no. 36 (September 2, 2021): e2101410118. http://dx.doi.org/10.1073/pnas.2101410118.
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In human neurodegenerative diseases, neurons can transfer toxic protein aggregates to surrounding cells, promoting pathology via poorly understood mechanisms. In Caenorhabditis elegans, proteostressed neurons can expel neurotoxic proteins in large, membrane-bound vesicles called exophers. We investigated how specific stresses impact neuronal trash expulsion to show that neuronal exopher production can be markedly elevated by oxidative and osmotic stress. Unexpectedly, we also found that fasting dramatically increases exophergenesis. Mechanistic dissection focused on identifying nonautonomous factors that sense and activate the fasting-induced exopher response revealed that DAF16/FOXO-dependent and -independent processes are engaged. Fasting-induced exopher elevation requires the intestinal peptide transporter PEPT-1, lipid synthesis transcription factors Mediator complex MDT-15 and SBP-1/SREPB1, and fatty acid synthase FASN-1, implicating remotely initiated lipid signaling in neuronal trash elimination. A conserved fibroblast growth factor (FGF)/RAS/MAPK signaling pathway that acts downstream of, or in parallel to, lipid signaling also promotes fasting-induced neuronal exopher elevation. A germline-based epidermal growth factor (EGF) signal that acts through neurons is also required for exopher production. Our data define a nonautonomous network that links food availability changes to remote, and extreme, neuronal homeostasis responses relevant to aggregate transfer biology.
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Wagle, S., N. Joshi, and K. Prajapati. "Management of a non-vital immature tooth using MTA as an apical plug: Two case reports." Journal of Chitwan Medical College 5, no. 1 (March 31, 2015): 41–46. http://dx.doi.org/10.3126/jcmc.v5i1.12574.
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MTA appears to be a valid option for apexification with its main advantage being, the speed at which the treatment can be completed. A major problem in performing endodontics in immature teeth with necrotic pulp and wide open apices is obtaining an optimal seal of the root-canal system. Mineral Trioxide Aggregate (MTA), has been proposed as a potential material to create an apical plug at the end of the root-canal system, thus preventing the extrusion of filling materials.DOI: http://dx.doi.org/10.3126/jcmc.v5i1.12574
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Luo Jian, Yu, Tong Xin, and Wu Huang Yi. "Experimental Study on Acoustic Characteristics of Particle Breakage Under Combined Shear and Extrusion Load." Science of Advanced Materials 13, no. 5 (May 1, 2021): 846–56. http://dx.doi.org/10.1166/sam.2021.3945.
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The jaw crushing loading process is a typical loading process of combined shearing and extrusion. In this paper, by establishing a complete jaw crushing loading process, the sonic test method is used to determine and analyze the particle crushing law to explore acoustic characteristics of particle crushing under the combined action of shear and extrusion. A jaw crushing tester is used to simulate the jaw crushing process of sand aggregate specimens. A rock-soil sound wave detector is used to measure the sound speed, sound amplitude, and sound intensity during the simulated jaw crushing process. It is found that when the jaw angle variation range is 2.6°, the inlet-outlet ratio is 0.332 and the motor speed is 15 r/min, the sound velocity and the sound amplitude curves fluctuate more drastically and the sound intensity is higher. The crushing evaluation of the sand aggregate specimens, which have experienced crushing simulation, shows that when the jaw angle variation range is 3.0°, the inlet-outlet ratio is 0.332 and the motor speed is 33 r/min, higher crushing energy rate and crushing rate are achieved. Through the comparative analysis of each group’s acoustic parameters and crushing evaluations, it is found that both the acoustic parameters and the crushing evaluations reflect the crushing process, but they have similarities and differences. Therefore, to some extent, the acoustic parameters in the crushing process can be regarded as significant indicators for evaluating the crushing effect. This conclusion may be a reference for optimizing working parameters and structural parameters of crushing equipment.
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BABA, Akio, and Akiko MORI. "EFFECTS OF AGGREGATE SIZE ON FLEXURAL STRENGTH AND DENSIFICATION OF CEMENTITIOUS MATERIALS PRODUCED BY EXTRUSION MOULDING." Journal of Structural and Construction Engineering (Transactions of AIJ) 62, no. 494 (1997): 1–6. http://dx.doi.org/10.3130/aijs.62.1_4.
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Chang, Seok-Woo, Tae-Seok Oh, WooCheol Lee, Gary Shun-Pan Cheung, and Hyeon-Cheol Kim. "Long-term observation of the mineral trioxide aggregate extrusion into the periapical lesion: a case series." International Journal of Oral Science 5, no. 1 (April 2013): 54–57. http://dx.doi.org/10.1038/ijos.2013.16.
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Pawar, Ritesh Balasaheb, and Sumanthini V. Margsahayam. "Management of a Traumatized Open Apex Tooth with a Combination of Mineral Trioxide Aggregate Apical Plug and Platelet-rich Fibrin Apical Matrix." Journal of Contemporary Dentistry 6, no. 1 (2016): 57–62. http://dx.doi.org/10.5005/jp-journals-10031-1142.
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ABSTRACT The absence of a natural apical constriction in permanent tooth makes endodontic treatment a challenge. Traditionally, calcium hydroxide was used for inducing the formation of an apical barrier. Currently, mineral trioxide aggregate (MTA) has shown promising results for apexification procedures. In an open apex, it is imperative to limit the MTA placement within the confines of the root canal for predictable healing. The placement of an internal matrix may limit the extrusion to some extent. Many materials can be used as internal matrix such as collagen membrane, calcium sulphate, hydroxyapatite, freeze dried bone, and platelet-rich fibrin (PRF) among others. This case report presents a successful demonstration of the management of an open apex using MTA placed over an internal apical matrix of PRF. How to cite this article Pawar RB, Margsahayam SV, Shenoy VU, Shaikh SAH. Management of a Traumatized Open Apex Tooth with a Combination of Mineral Trioxide Aggregate Apical Plug and Platelet-rich Fibrin Apical Matrix. J Contemp Dent 2016;6(1):57-62.
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Smith, A. W. F., D. N. Crowther, P. J. Apps, and Philip B. Prangnell. "Ultra-Fine Grained High Carbon Steel by Innovative Deformation." Materials Science Forum 550 (July 2007): 301–6. http://dx.doi.org/10.4028/www.scientific.net/msf.550.301.
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It is well known that the refinement of grain size in metals leads to a significant improvement in specific mechanical properties. Processing schedules have been investigated aimed at producing an homogeneous ultra-fine ferrite and spheroidised carbide aggregate microstructure in high carbon (CMn) steels (0.6-1.2wt%C), via conventional ‘warm’ rolling and innovative Equal Channel Angular Extrusion (ECAE). Suitable deformation schedules were determined from dilatometry and thermo-mechanical Gleeble simulations. Evidence of an ultra-fine ferrite and carbide aggregate microstructure following ‘warm’ rolling was observed. A significant improvement in tensile strength, particularly proof stress was also noted in comparison to material deformed at higher temperatures. Concurrent ECAE experiments investigated microstructural evolution with incremental strain. Extensive analysis was carried out using various techniques, including high resolution Electron Back Scattered Diffraction (EBSD). Evidence of ferrite grain refinement was noted in a eutectoid composition steel. A sub-micron ferrite structure was observed following high strains (ε~3.33) and the mechanical properties exhibited a marked increase in tensile strength.
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Hudiyanti, Dwi, Tri Joko Raharjo, Narsito Narsito, and Sri Noegrohati. "INVESTIGATION ON THE MORPHOLOGY AND PROPERTIES OF AGGREGATE STRUCTURES OF NATURAL PHOSPHOLIPIDS IN AQUEOUS SYSTEM USING CRYO-TEM." Indonesian Journal of Chemistry 12, no. 1 (February 14, 2012): 57–61. http://dx.doi.org/10.22146/ijc.21372.
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Cryogenic transmission electron microscopy (Cryo-TEM) was used to investigate the aggregates morphology and properties of candle tree (Aleurites moluccana) endosperm, sesame (Sesamum indicum L. syn.) seeds, and coconut (Cocos nucifera) endosperm phospholipids in dilute aqueous system. The micrographs showed that candle tree phospholipids formed planar bilayer and cluster of vesicles with lipid droplets, while coconut and sesame phospholipids formed well-defined unilamellar vesicles. The vesicles size could be as small as 50 nm in diameter. Coconut phospholipids also showed a good bending ability. Formation of clusters of vesicles was also found in coconut phospholipids dispersion, but this cluster was easily broken by extrusion through a small pore membrane.
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Sambucci, Matteo, Danilo Marini, and Marco Valente. "Tire Recycled Rubber for More Eco-Sustainable Advanced Cementitious Aggregate." Recycling 5, no. 2 (May 11, 2020): 11. http://dx.doi.org/10.3390/recycling5020011.
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This research focused on using ground tire rubber (GTR) with different grain sizes as a replacement for the mineral aggregates used in a cement-based mixture suitable for extrusion-based Additive Manufacturing. The use of two types of GTR particles and the possibility to apply rubberized mixtures in advanced manufacturing technologies are the innovative aspects of this work. At the base of this strategy is the possibility of achieving cementitious aggregates, which would potentially be improved regarding some technological-engineering requirements (lightness, thermal-acoustic insulation, energy dissipation capacity, durability) and environmentally sustainable. The integration of waste tires into cement-based materials is a promising solution for the reuse and recycling of such industrial waste. In addition, this approach may involve a considerable reduction in the use of natural resources (sand, water, coarse mineral aggregates) needed for the building materials production. The purpose of the research was to investigate the effect of sand-GTR replacement on certain chemical-physical properties of mixtures (permeable porosity, surface wetness, and water sorptivity), closely related to material durability. Besides, the role of rubber on the printability properties of the fresh material was evaluated. GTR fillers do not alter the rheological properties of the cement material, which was properly extruded with better print quality than the reference mixture. Concerning chemical-physical characterization, the GTR powder-granules synergy promotes good compaction of the mixture, hinders the cracks propagation in the cement matrix, decreases the permeable porosity, improves the surface hydrophobicity and preserves optimal water permeability.
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Kato, Atsushi, Maiko Nishioka, Yoshihiro Sato, Etsuko Nagano, Riko Yamashita, Norihito Kimura, and Takehiko Taguchi. "STUDIES ON BOUND RUBBER OF CB BEFORE/AFTER VULCANIZATION OF ISOPRENE RUBBER." Rubber Chemistry and Technology 87, no. 3 (September 1, 2014): 471–85. http://dx.doi.org/10.5254/rct.14.86974.
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ABSTRACT The high abrasion furnace (HAF), fast extrusion furnace (FEF), and fine thermal (FT) loadings used in this study were adjusted to keep the carbon black (CB)–specific area of cetyl trimethyl ammonium bromide adsorption to 2490 m2g−1. Their polyisoprene (IR) compounds and vulcanizates were investigated. Regarding the dependence of the CB gel fraction (FCB gel) on the IR gel/CB weight ratio (WRIR/CB), the amount of CB in the CB gel increased with a larger CB aggregate size, whereas the amount of the IR gel decreased. With regard to the dependence of the activation energy (ΔE(T2)) of the spin–spin relaxation time (T2) on the CB aggregate size, an immobilized rubber layer around CB formed more easily in the order of FT < FEF < HAF. Moreover, it became clear from the relationship between WRIR/CB and ΔE(T2) that the amount of the IR gel in the CB gel increased with decreasing ΔE(T2). The unique ratio of the surface area to the volume of CB aggregates (SCB/VCB) was obtained from results of three-dimensional transmission electron microscopy observation. The dependence of the amount of dibutyl phthalate (DBP) adsorption and compressed DBP adsorption on SCB/VCB was approximately linear, which suggested that SCB/VCB was closely related to CB aggregates and CB agglomerates. The linear relationship seen between SCB/VCB and ΔE(T2) revealed that an immobilized rubber layer was present around CB. The dependence of (qCB/qIR)(WRIR/CB) on SCB/VCB was also investigated using the densities (ρIR and ρCB) of IR and CB. The slope (tirl) of their approximately linear relationship was about 3.9 nm, which almost agreed with the bound rubber thickness reported in the literature to date. It is also inferred that because the intercept (α), which reflects the change in the IR gel weight fraction, was about 0.04 (4%), the IR gel weight fraction changed very little between before and after vulcanization.
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Zareiyan, Babak, and Behrokh Khoshnevis. "Interlayer adhesion and strength of structures in Contour Crafting - Effects of aggregate size, extrusion rate, and layer thickness." Automation in Construction 81 (September 2017): 112–21. http://dx.doi.org/10.1016/j.autcon.2017.06.013.
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Ivanova, Irina, and Viktor Mechtcherine. "Effects of Volume Fraction and Surface Area of Aggregates on the Static Yield Stress and Structural Build-Up of Fresh Concrete." Materials 13, no. 7 (March 27, 2020): 1551. http://dx.doi.org/10.3390/ma13071551.
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With increasing interest in the use of additive manufacturing techniques in the construction industry, static rheological properties of fresh concrete have necessarily come into focus. In particular, the knowledge and control of static yield stress (SYS) and its development over time are crucial for mastering formwork-free construction, e.g., by means of layered extrusion. Furthermore, solid understanding of the influences of various concrete constituents on the initial SYS of the mixture and the structural build-up rate is required for purposeful material design. This contribution is concentrated on the effect of aggregates on these rheological parameters. The volume fraction of aggregates was varied in the range of 35% to 55% by volume under condition of constant total surface area of the particles. The total surface area per unit volume of cement paste was equal to 5.00, 7.25 and 10.00 m²/L, conditioned on the constant volume fraction of aggregates. Both variations were enabled by changing the particle size distributions of the aggregates while holding the cement paste composition constant for all concrete mixtures. To characterise the SYS and the structural build-up, constant shear rate tests with a vane-geometry rotational rheometer were performed. It was found that in the ranges under investigation the variation in volume fraction had a more pronounced effect on the static rheological properties of concrete than did the variation in surface area. An accurate mathematical description of the relationship between the initial SYS of concrete and the relative volume fraction of aggregate based on the Chateau–Ovarlez–Trung model was proposed. Challenges in deriving a similar relationship for the structural build-up rate of concrete were highlighted.
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Sumanthini, M. V., and Mausami A. Malgaonkar. "Management of non vital maxillary central incisors with open apex using Mineral Trioxide Aggregate apical plugs – Case report." Journal of Contemporary Dentistry 1, no. 2 (2011): 40–43. http://dx.doi.org/10.5005/jcd-1-2-40.
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Abstract The case report describes the treatment of maxillary central incisors with open apex, due to apical root resorption, as a consequence of trauma experienced three years earlier. Open apices pose a challenge during endodontic treatment. Several materials and methods have been widely studied and tried in the past. Obtaining an adequate apical seal is of paramount importance regardless of the material or technique used. In the present case the involved teeth were treated nonsurgically using white Mineral Trioxide Aggregate (MTA) as an artificial apical barrier. The treated teeth were asymptomatic and the follow up clinical and radiographic examination showed healing with apparent regeneration of periradicular tissues. Extrusion of MTA beyond the root end was not an obstacle in the healing process. MTA can be considered an effective material to treat infected open apex teeth with large periapical lesions.
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Goyal, Ayush, Vineeta Nikhil, and Padmanabh Jha. "Absorbable Suture as an Apical Matrix in Single Visit Apexification with Mineral Trioxide Aggregate." Case Reports in Dentistry 2016 (2016): 1–6. http://dx.doi.org/10.1155/2016/4505093.
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Several procedures have been recommended to induce the root end barrier formation in teeth with open apices. Conventional treatment for such cases will require many appointments with an average duration of 12.9 months. During this period, the root canal is susceptible to reinfection from around the provisional restoration, which may promote apical periodontitis and arrest of apical repair. Mineral trioxide aggregate (MTA) has been successfully used for one visit apexification wherein the root canal can be obturated within 24 hours after placement of MTA. Using a matrix prior to the placement of MTA avoids its extrusion, reduces leakage in the sealing material, and allows favorable response of the periapical tissues. This report presents a case of apexification where an absorbable suture was used as an apical matrix. Use of an absorbable suture circumvents all the problems associated with other conventional materials. Conclusion. Placement of the matrix made from the suture material is predictable and is easily positioned at the apex and the length can be adjusted as required. 10-month follow-up of the case shows resorbed matrix and bone healing in the periapical region. The patient was asymptomatic during the whole follow-up period and tooth exhibited mobility within physiologic limits and was functioning normally.
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Vespalec, Arnošt, Josef Novák, Alena Kohoutková, Petr Vosynek, Jan Podroužek, David Škaroupka, Tomáš Zikmund, Josef Kaiser, and David Paloušek. "Interface Behavior and Interface Tensile Strength of a Hardened Concrete Mixture with a Coarse Aggregate for Additive Manufacturing." Materials 13, no. 22 (November 15, 2020): 5147. http://dx.doi.org/10.3390/ma13225147.
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3D concrete printing technology (3DCP) is a relatively new technology that was first established in the 1990s. The main weakness of the technology is the interface strength between the extruded layers, which are deposited at different time intervals. Consequently, the interface strength is assumed to vary in relation to the time of concrete casting. The proposed experimental study investigated the behavior of a hardened concrete mixture containing coarse aggregates that were up to 8 mm in size, which is rather unusual for 3DCP technology. The resulting direct tensile strength at the layer interface was investigated for various time intervals of deposition from the initial mixing of concrete components. To better understand the material behavior at the layer interface area, computed tomography (CT) scanning was conducted, where the volumetric and area analysis enabled validation of the pore size and count distribution in accordance with the layer deposition process. The analyzed CT data related the macroscopic anisotropy and the resulting crack pattern to the temporal and spatial variability that is inherent to the additive manufacturing process at construction scales while providing additional insights into the porosity formation during the extrusion of the cementitious composite. The observed results contribute to previous investigations in this field by demonstrating the causal relationships, namely, how the interface strength development is determined by time, deposition process, and pore size distribution. Moreover, in regard to the printability of the proposed coarse aggregate mixture, the specific time interval is presented and its interplay with interface roughness and porosity is discussed.
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ZHANG, ZHIMIN, and BAOHONG ZHANG. "INFLUENCE OF T5 TREATMENT ON MICROSTRUCTURE AND PROPERTIES OF EXTRUDED ZK60 MAGNESIUM ALLOY." International Journal of Modern Physics B 23, no. 06n07 (March 20, 2009): 996–1001. http://dx.doi.org/10.1142/s0217979209060361.
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As-cast ZK60 magnesium alloy that has been treated by homogenizing was forward extruded at 380°C and different extrusion ratios. Half of the extruded samples were treated by T5 treatment (10 hours at 170°C). The microstructure and mechanical properties of extruded samples that have been treated by T5 treatment and not been treated by T5 treatment have been measured. Experimental results show that the T5 treatment of extruded ZK60 magnesium alloy will cause the tensile strength and hardness to increase in some sort, the yield strength to increase obviously, but elongation to decrease slightly. When ZK60 magnesium alloy is extruded at 380°C, the second phase, MgZn and a small quantity of MnZn 2, will precipitate, and the distribution of second phase is even and dispersed. After T5 treatment, the change of grain size is not obvious, but the quantity of precipitated phase obviously increases comparing with extruded samples, and some of the precipitated phase aggregate and grow.
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Laidmäe, Ivo, Andres Meos, Irja Alainezhad Kjærvik, Sveinung G. Ingebrigtsen, Nataša Škalko-Basnet, Kalle Kirsimäe, Tavo Romann, Urmas Joost, Vambola Kisand, and Karin Kogermann. "Electrospun Amphiphilic Nanofibers as Templates for In Situ Preparation of Chloramphenicol-Loaded Liposomes." Pharmaceutics 13, no. 11 (October 20, 2021): 1742. http://dx.doi.org/10.3390/pharmaceutics13111742.
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The hydration of phospholipids, electrospun into polymeric nanofibers and used as templates for liposome formation, offers pharmaceutical advantages as it avoids the storage of liposomes as aqueous dispersions. The objective of the present study was to electrospin and characterize amphiphilic nanofibers as templates for the preparation of antibiotic-loaded liposomes and compare this method with the conventional film-hydration method followed by extrusion. The comparison was based on particle size, encapsulation efficiency and drug-release behavior. Chloramphenicol (CAM) was used at different concentrations as a model antibacterial drug. Phosphatidylcoline (PC) with polyvinylpyrrolidone (PVP), using ethanol as a solvent, was found to be successful in fabricating the amphiphilic composite drug-loaded nanofibers as well as liposomes with both methods. The characterization of the nanofiber templates revealed that fiber diameter did not affect the liposome size. According to the optical microscopy results, the immediate hydration of phospholipids deposited on the amphiphilic nanofibers occurred within a few seconds, resulting in the formation of liposomes in water dispersions. The liposomes appeared to aggregate more readily in the concentrated than in the diluted solutions. The drug encapsulation efficiency for the fiber-hydrated liposomes varied between 14.9 and 28.1% and, for film-hydrated liposomes, between 22.0 and 77.1%, depending on the CAM concentrations and additional extrusion steps. The nanofiber hydration method was faster, as less steps were required for the in-situ liposome preparation than in the film-hydration method. The liposomes obtained using nanofiber hydration were smaller and more homogeneous than the conventional liposomes, but less drug was encapsulated.
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Chandra, Praveen, Sonali Roy, Archana Kumari, Ritika Agarwal, Pinki Bankoti, and Farah Ahmed. "Evaluation of healing of periapical tissue in permanent incisors with open apices after unintentional extrusion of mineral trioxide aggregate – A retrospective study." Journal of Pharmacy And Bioallied Sciences 13, no. 5 (2021): 97. http://dx.doi.org/10.4103/jpbs.jpbs_570_20.
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Weger, Daniel, and Christoph Gehlen. "Particle-Bed Binding by Selective Paste Intrusion—Strength and Durability of Printed Fine-Grain Concrete Members." Materials 14, no. 3 (January 27, 2021): 586. http://dx.doi.org/10.3390/ma14030586.
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The selective paste intrusion (SPI) describes a selective binding, additive manufacturing method. SPI bonds thin layers of aggregate by cement paste locally. Currently, SPI can achieve higher compressive strength, durability, and easier unpacking behavior compared to other selective binding methods suitable for the production of concrete structures. Particle-bed based methods not only achieve much higher surface resolutions than depositing (extrusion)-based additive manufacturing methods but also have no restrictions in freedom of form. However, the mechanical performance of SPI components strongly depends on the void content between the individual layers and thus the penetration behavior of the cement paste. This paper presents direction-dependent measurements of the strength and durability of SPI-printed components compared to casted specimens with the same mixing composition. The results show compressive strength values between 70 and 78 MPa after 7 d, flexural strength of 1/10 without reinforcement, a high freeze–thaw resistance, no detectable carbonation after 182 days of exposure under ambient CO2–conditions, and after 28 days under increased CO2 content of 2 vol % as well as low chloride penetration resistances. All tests showed in almost all cases no dependency on the layer orientation.
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Mendes, T. M., G. Morales, and P. J. Reis. "Use of basaltic waste as red ceramic raw material." Cerâmica 62, no. 362 (June 2016): 157–62. http://dx.doi.org/10.1590/0366-69132016623621955.
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Abstract Nowadays, environmental codes restrict the emission of particulate matters, which result in these residues being collected by plant filters. This basaltic waste came from construction aggregate plants located in the Metropolitan Region of Londrina (State of Paraná, Brazil). Initially, the basaltic waste was submitted to sieving (< 75 μm) and the powder obtained was characterized in terms of density and particle size distribution. The plasticity of ceramic mass containing 0%, 10%, 20%, 30%, 40% and 50% of basaltic waste was measured by Atterberg method. The chemical composition of ceramic formulations containing 0% and 20% of basaltic waste was determined by X-ray fluorescence. The prismatic samples were molded by extrusion and fired at 850 °C. The specimens were also tested to determine density, water absorption, drying and firing shrinkages, flexural strength, and Young's modulus. Microstructure evaluation was conducted by scanning electron microscopy, X-ray diffraction, and mercury intrusion porosimetry. Basaltic powder has similar physical and chemical characteristics when compared to other raw materials, and contributes to ceramic processing by reducing drying and firing shrinkage. Mechanical performance of mixtures containing basaltic powder is equivalent to mixtures without waste. Microstructural aspects such as pore size distribution were modified by basaltic powder; albite phase related to basaltic powder was identified by X-ray diffraction.
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Perez, Vanessa, Max E. Johansen, Wenche Jy, Larry Horstman, and Yeon S. Ahn. "Interaction Of Platelets With Red Cell-Derived Microparticles (RMP): RMP Increase Platelet Aggregate Size In a Shear-Dependent Manner." Blood 122, no. 21 (November 15, 2013): 3580. http://dx.doi.org/10.1182/blood.v122.21.3580.3580.
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Abstract Background Red cell microparticles (RMP) have come to recent attention as putative mediators of hemostasis. We reported that RMP improve hemostatic defect of blood samples of thrombocytopenia and thrombocytopathy and augment platelet function. To investigate possible mechanisms of this activity, we measured the effect of RMP on shear-dependent platelet adhesion and aggregation in whole blood. Methods RMP were produced by high-pressure extrusion of washed, packed RBC. The RMP produced in this way are similar to natural circulating RMP in phenotype and most functional assays. Blood was collected in citrate Vacutainers from normal healthy staff volunteers, and first 3 mL discarded to minimize artifact of platelet activation due to tissue factor. It was tested within 2 hours of drawing. Variable shearing rates were applied by a cone-and-plate device, the DiaMed Impact-R, which yields photomicrographs of objects adhering to the plate, and data including percent surface coverage (SC), number objects adhering (OBJ) per mm2, and mean aggregate size (AS) in μm2. Initially, 4μL of either RMP (1.0 x 108/μL) or saline were mixed with 126μL of whole blood obtained as above, and incubated in a microcentrifuge tube for 60s. The mixtures were pipetted to a well of the device and run at a selected shear rate (range 900s-1 to 2700s-1) for 2 minutes. Blood was then carefully drawn off and the wells were washed gently with deionized water. Wells were stained with May-Grünwald stain for 60s, and excess removed. When dry, micrographs of the well surfaces were taken. The most promising shear rates (1125 s-1, 1575s-1, 1800s-1, 2025s-1) were retested with higher numbers of RMP in the 130μL volume. Results Addition of RMP vs. saline (control) induced increased AS over a range of shear rates. For example, 4μL RMP (1x108/μL) running at 2250s-1 increased AS by 34.8%, from 59.2 ±25.1μm2 to 79.8 ±24.7μm2 (n=15, p=0.01). To investigate effect of RMP concentration at fixed shear rate of 1575s-1, we found that 8μL RMP induced increase of 12.0 μm2, 12μL RMP by 24.8 μm2, 16μL by 26.7 μm2, and 20μL by 26.3 μm2; p<0.05 and n=4 replicates for all. As seen by the trend, this effect on AS reached a plateau at 20 μL RMP. With fixed volume of RMP added and varying shear rate, we found the largest RMP-induced increase in AS occurred at 1125s-1 shear rate: 16μL of RMP increased aggregate size to 172% of control (from 41.3 ±10.2μm2 to 71.0 ±2.6μm2; n=3, p=0.02). With 1/4 as much RMP (4 μL), the peak effect occurred at 1125s-1. We did not observe any significant differences in SC at any shear rate or RMP volume. OBJ was generally lower as AS increased, but this did not reach significance. Conclusion/Discussion RMP increased the size of platelet aggregates under shear, indicating enhanced platelet adhesion by RMP. This effect varied with shear rate: larger amounts of RMP had maximum effect at lower shear rates; smaller amounts of RMP required higher shear to exert maximum effect. These effects are seen at physiologically relevant shear rates (200 - 2000s-1 or higher in pathology such as hypertension or valve defects). Due to the absence of endothelia from this model, high shear was required to induce maximum adhesion. Previous study has indicated the important role of GPIIb/IIIa in platelet adhesion and aggregate size under high shear [Varon, et al; Am Heart J, 1998]. We postulate that RMP may be acting in a GPIIb/IIIa dependent manner to enhance aggregate size. This was consistent with the findings that RMP-induced augmentation of platelet aggregation at relevant levels of ADP or AA concentrations in heparinized blood [Jy, et al; Thromb Haemost, in press]. We are continuing to investigate conditions affecting the interactions between RMP and platelets. Disclosures: No relevant conflicts of interest to declare.
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Jy, Wenche, Max E. Johansen, Carlos Bidot, Powei Chen, Lawrence L. Horstman, and Yeon S. Ahn. "Interaction of Red Cell Microparticles (RMP) with Platelets: Potential Role of RMP in Hemostasis and Thrombosis,." Blood 118, no. 21 (November 18, 2011): 3263. http://dx.doi.org/10.1182/blood.v118.21.3263.3263.
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Abstract Abstract 3263 Introduction: We previously reported data indicating that RMP are well suited for use as hemostatic agent for treating bleeding disorders (Jy et al, Hemophilia 17:4, 2011). Previous studies have shown that RMP can contribute to RBC-related thrombotic complications such as sickle cell disease and PNH. Microparticles (MP) derived from platelets (PMP), endothelia (EMP), and leukocytes (LMP) are believed to play a role in hemostasis and thrombosis. They can adhere to blood cells and endothelia, facilitating prothrombotic and proinflammatory reactions. However, less is known about interaction of RMP with cells and their potential role in hemostasis and thrombosis. Here we report evidence of interaction of RMP with platelets resulting in enhanced platelet aggregation and increased size of adherent platelet aggregates induced by shear stress. Methods: (i) RMP were prepared by high-pressure extrusion of washed RBC. (ii) Platelet aggregation was performed in a Chrono-log aggregometer. PRP (490 μL) was mixed with 10 μL of RMP (1 × 108 /mL final conc.) for 5 min, then low-dose activating agent (ADP 0.2 μM, or arachidonic acid (AA) 0.3 mM) was added. (iii) Shear-induced platelet adhesion was measured in a cone-and-well device (Diamed Impact-R). Whole blood was pre-incubated with RMP as above for 10 min, then subjected to various shear rates (900, 1800, 2700 sec−1) for 1 min. The adherent platelets were then washed, stained, and quantitated by image analyzer. (iv) RMP-platelet interaction employed 2-color flow cytometry. RMP-platelet conjugates were identified by co-expression of α-CD41-FITC and α-glycophrin A-PE, in both the free platelet and micro-aggregated platelet populations. Results: (1) Platelet aggregation: Addition of RMP to PRP did not induce platelet aggregation. However, RMP enhanced platelet aggregation induced by low-dose ADP or AA. Low-dose ADP alone induced a transient increase of aggregation peaking at 25–35% followed by slow disaggregation to 0–5% at 10 min; but in presence of RMP, a similar rate (slope) of aggregation was seen but peaking at 50–60% and disaggregation was abolished. Using AA, the RMP also potentiated aggregation from 20–30% to 50–60%. These results were obtained with heparinized PRP. Interestingly, when citrated PRP was used, the RMP effect was negligible. (2) Shear-induced platelet adhesion: At 1800 sec−1 shear rate, which approximates venous blood flow, addition of RMP increases the adhered mean aggregate size from 47 to 53 μm2 (p<0.03) but decreased the number of adhering objects from 1380 to 1242 (p<0.01). At lower (900 sec−1) or higher (2700 sec−1) rate, the RMP effects disappeared. (3) Two-color flow cytomrtry showed that RMP do not conjugate with single platelets but do with platelet micro-aggregates induced by ADP. When platelet micro-aggregates are diluted with PBS (1:10), they usually disaggregate rapidly (t1/2 = 10–15 min) but in presence of RMP, the rate of dissociation was much slower (t1/2 = 30–40 min). Conclusions: These results reveal that RMP can interact with weakly activated platelets to enhance platelet adhesion and aggregation and stabilize platelet aggregates. Since these effects were seen with heparinized but not with citrated blood, calcium may be a cofactor for this interaction. We suggest that RMP-platelet interaction could play a role in hemostasis, and that therapeutic RMP may improve hemostatic abnormality in thrombocytopenia and platelet dysfunction partly by this mechanism, augmenting the limited platelet function. Disclosures: No relevant conflicts of interest to declare.
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NOVAK, DMІTRIY, and KATERYNA MARYNIAKA. "РОЗРОБЛЕННЯ ПРОГРАМНОГО ЗАБЕЗПЕЧЕННЯ ДЛЯ ОЦІНЮВАННЯ ОДНОРІДНОСТІ РОЗПОДІЛУ НАПОВНЮВАЧА В ПОЛІМЕРНІЙ МАТРИЦІ." Technologies and Engineering, no. 6 (January 10, 2022): 37–44. http://dx.doi.org/10.30857/2786-5371.2021.6.4.
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Purpose. Creation of software for evaluating the uniformity of distribution of the filler in a polyethylene matrix.Methodology. Software development was carried out using the Python programming language and libraries: PIL, Numpy, Matplotlib, Xlsxwriter. The suitability of the developed software for use was determined by verifying it. During this verification, polyethylene compositions filled with colloidal graphite in the form of compressed films were evaluated. To obtain these compositions, we chose P6006AD grade polyethylene and C-1 colloidal graphite. Samples of polyethylene compositions were obtained in two stages: 1) obtaining a strand by extrusion; 2) additional mixing of the composition on a disc mixer and pressing the obtained compositions into a film.Findings. The software has been developed to assess the uniformity of the distribution of the filler in the polyethylene matrix. The data were established on the dependence of the coefficient of heterogeneity of polyethylene compositions on the content of colloidal graphite with use of the developed software. The increase in the content of the filler leads to a decrease in its heterogeneity. It is shown that this effect can be explained by the structuring of the filler in the polyethylene matrix. Despite the formation of aggregates in polyethylene compositions, a significant amount of small colloidal particles of graphite is located between the aggregate space. This leads to a certain leveling of the concentration in the film and reduces its inhomogeneity.Scientific novelty. The influence of the content of colloidal graphite on the homogeneity of polyethylene compositions is determined. It is shown that with an increase in the graphite content from 0 to 20% vol. the coefficient of heterogeneity of the composition decreases from 5.3% to 3.9%, which is due to the structuring of the filler in the polyethylene matrix.Practical value. Software that makes it possible to evaluate the uniformity of the distribution of filler particles in a polymer matrix, and can be used to study the quality of mixing of polymer composite materials has been developed.
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OLIVEIRA, Fernando Lara D., Caroline C. SANTA-ROSA, Bernardo Henrique Silva BAMBIRRA, Elen Marise Castro de OLIVEIRA, Lia Silva de CASTILHO, and Maria Elisa de Souza e. SILVA. "Root fracture in patient in the pre-liver transplantation phase." RGO - Revista Gaúcha de Odontologia 65, no. 2 (June 2017): 185–90. http://dx.doi.org/10.1590/1981-863720170002000153098.
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ABSTRACT Liver transplantation is the treatment of choice for end-stage liver disease patients, and offers them the possibility of returning to active and longer life. A dental evaluation before transplantation is a recommended prerequisite to avoid oral infections, which can worsen the patient’s overall situation. This case report refers to the root fracture of an anterior tooth in a patient who was undergoing dental treatment prior to liver transplantation. On clinical examination, the maxillary right central incisor (11) presented without color change, but with mobility in the buccolingual direction, slight flaring and extrusion, and fistula in the attached gingiva on the distal side of tooth 11. The patient reported that he had suffered a trauma in that region 30 years before. The radiographic examination showed a horizontal fracture of the middle third of the root, associated with bone damage, indicated by a radiolucent area at the distal surface of 11. The proposed treatment consisted of: scraping procedure and straightening of the distal surface, radical endodontic treatment of the coronal portion of the root, subsequent filling with Mineral Trioxide Aggregate and dental immobilization. The clinical and radiographic follow-up at three-monthly intervals allowed us to observe gradual regression of the lesion with bone formation, contributing to maintenance of the patient’s general and emotional health, preserving his smile and quality of life.
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Krulwich, T. A., J. Cheng, and A. A. Guffanti. "The role of monovalent cation/proton antiporters in Na(+)-resistance and pH homeostasis in Bacillus: an alkaliphile versus a neutralophile." Journal of Experimental Biology 196, no. 1 (November 1, 1994): 457–70. http://dx.doi.org/10.1242/jeb.196.1.457.
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Both neutralophilic Bacillus subtilis and alkaliphilic Bacillus firmus OF4 depend upon electrogenic Na+/H+ antiporters, which are energized by the gradients established by respiration-coupled proton extrusion, to achieve Na(+)-resistance and pH homeostasis when the external pH is very alkaline. The interplay of proton and sodium cycles is discussed. In B. subtilis, pH homeostasis, up to pH9, can be achieved using K+ when Na+ is unavailable or when the gene encoding the Na+/H+ antiporter that is involved in Na(+)-dependent pH homeostasis is disrupted. That gene is a member of the tetracycline efflux family of genes. A second gene, encoding a Na+/H+ antiporter that functions in Na(+)-resistance, has been identified, and candidates for the K+/H+ antiporter genes are under investigation. Aggregate Na+/H+ antiport activity in B. subtilis is as much as 10 times lower than in the alkaliphile, and the neutralophile cannot regulate its internal pH upon a shift to pH 10.5. Upon such a shift, there is a pronounced reduction in the generation of a primary electrochemical proton gradient. The alkaliphile, by contrast, maintains substantial driving forces and regulates its internal pH in an exclusively Na(+)-coupled manner upon shifts to either pH 8.7 or 10.5. One gene locus has been identified and a second locus has been inferred as encoding relevant antiporter activities.
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Ahn, Yeon S., Wenche Jy, Lawrence L. Horstman, Max E. Johansen, and Carlos Bidot. "Red Cell Microparticles (RMP) As Hemostatic Agent: Summary of Recent Advances." Blood 118, no. 21 (November 18, 2011): 2260. http://dx.doi.org/10.1182/blood.v118.21.2260.2260.
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Abstract Abstract 2260 Introduction: Microparticles (MP) derived from platelets (PMP), endothelia (EMP) and leukocytes (LMP) have received much attention as biomarkers in cardiovascular and inflammatory disorders. However MP derived from red cells (RMP) have been less well investigated. We previously presented evidence for the efficacy of RMP as a hemostatic agent in vivo and other effects such as on thrombin generation. Here we report data on in vitro proxies of hemostatic potential of RMP which further support its expected value as a hemostatic agent, and provide clues about mechanism of action. Methods: (i) RMP were produced by high-pressure extrusion of washed RBC. (ii) The effect of RMP on coagulation/clotting was assessed by thromboelastography (TEG) using whole blood or factor-deficient plasmas tested in presence vs. absence of added RMP (1×108/mL). Patient samples included those with coagulopathy, thrombocytopenia, thrombocytopathy. (iii) The effect of RMP on platelet aggregation was assessed by aggregometry (Chrono-Log). (iv) The effect of RMP on shear-induced platelet adhesion was by cone-and-well device (Diamed IMPACT-R) yielding measures of mean aggregate size (AS), percent surface coverage (SC) and number of objects (OBJ). Results: (1) RMP produced as above express procagulant phospholipids as judged by 20–30% of them binding annexin V. (2) RMP increased procoagulance in all factor-deficient plasmas tested (FII, V, VII, VIII, IX, X, XI, XII, XIII). The most pronounced effects were observed with FII, FVIII, FIX, FX deficiency, most markedly, FVIII and IX. RMP give significant correction for deficiencies as low as 5–10% normal levels. (3) RMP augmented platelet aggregation induced by low-dose ADP (0.2 μM) or arachidonic acid (0.3 mM). RMP largely eliminated dissociation of platelet aggregates after low-dose ADP. (4) At shear rate of 1800 sec−1, which approximates venous flow, aggregate size (AS) was significantly increased (p=0.02). (5) Using flow cytometry, RMP were observed to interact with platelet microaggregates expressing markers of activation, but not with free resting platelets. (6) RMP partly or completely corrected abnormal parameters seen on TEG in blood from patients with thrombocytopenia (aplastic anemia, ITP) as well as platelet dysfunctions induced by ASA or Plavix. It also improved or corrected abnormal parameters in coagulopathies such as hemophilia A with low inhibitor; and anticoagulant therapy with wafarin, LMWH, or Dabigatran. Summary/Discussion: (1) Increased procoagulance in all factor deficient plasma by RMP indicates that RMP provide anionic surface for clotting factors. Since this was most pronounced with FII, FVIII, FIX, and FX, and was strongest in FVIII, FIX, it appears that RMP have some specificity for assembly of tenase. (2) Correction of clotting abnormality in thrombocytopenia and platelet dysfunction by RMP suggests that RMP may provide additional catalytic surface for coagulation, as well as contributing modestly to clot strength. The latter effect may depend on presence of weakly activated platelets. (3) The increased maximum amplitude (MA) seen in TEG by RMP suggests that RMP may enhance platelet-fibrin interaction, increasing clot stability. Taken together, these data support the potential use of RMP as a universal hemostatic agent. Disclosures: No relevant conflicts of interest to declare.
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Lesovik, Valery S., Evgeny S. Glagolev, Michail Yu Elistratkin, Marina A. Pospelova, and Natalia I. Alfimova. "The Method of Creating and Measuring the Printability of Fine-Grained Concrete." Materials Science Forum 1017 (January 2021): 71–80. http://dx.doi.org/10.4028/www.scientific.net/msf.1017.71.
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One of the factors hindering the normal development of additive construction technologies is the lack of reasonable methods for evaluating the suitability of mixtures for printing. This makes it almost impossible to compare remotely the compositions of different developers, makes it difficult to develop equipment and regulatory documentation, without which it is impossible to complete industrial production. The paper considers the feasibility of introducing the concept of “printability” of compositions and “rheological technological index of mixtures” as a numerical indicator for its evaluation. The design of the device for determining the rheological technological index is described. The developed device has a low cost of production, is linked to standard equipment of construction laboratories and emulates the main types of effects on the mixture during the extrusion process. The effective method for ensuring the printability of fine-grained concretes is considered based on the joint use of traditional plasticizing additives with entrained agents – foaming agents for cellular concretes. The effect of these additives is realized at different scale levels (micro-and mesolevels (cement paste) – traditional superplasticizers; macro-level (fine aggregate) - entrained agents), which together provides high rheological technological indices and effectiveness of mixtures with increased amounts of sand, low W/C ratios and small dosages of these additives. The use of additional mineral or organic rheology modifiers that increase the cost of the mixture is not required in this case. The structural features and basic properties of the developed composites are studied, allowing making comparisons with the solutions of other developers, assessing the prospects of the proposed method of ensuring printability, and outlining directions for its further improvement.
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Amato, Mariana, Rocco Bochicchio, Giacomo Mele, Rosanna Labella, and Roberta Rossi. "Soil structure and stability in the spermosphere of myxosdiaspore chia (Salvia hispanica L.)." Soil Research 57, no. 6 (2019): 546. http://dx.doi.org/10.1071/sr18182.
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Mucilage produced by myxodiaspores has been mainly studied for its role in seed ecology. This work investigates changes due to mucilage in soil structure and stability in the spermosphere of the myxodiaspore crop chia (Salvia hispanica L.). In sandy-loam (S) repacked soil sown with chia and subjected to wetting–drying (DW), Computer Assisted X-ray micro tomography showed that extrusion of a mucilage capsule formed a pore of volume twice that of the seed, surrounded by a shell of particles with higher porosity and lower pore size than the bulk soil. In three soils (S; loam, L; and clay-loam, C) the aggregate stability index to wet sieving (Stw) decreased with one and two DW cycles. Application of 2% w/w mucilage increased Stw before and after DW, from 29% in C to more than 60-fold in S. Mucilage-amended samples after DW had higher or equal Stw compared with unamended soil before DW. Soil retained at the surface of hydrated diaspores exposed to water flow changed with soil texture (11.3, 90.5 and 91.7mg on each hydrated seed for S, L and C respectively) and chia genotype (6.7, 9.9 and 12.8mg per hydrated seed in BC and G8 long-day flowering mutants and commercial Black chia respectively). Our results showed that myxodiaspores affected soil structure by providing a microenvironment of altered porosity and high stability around the mucilage capsule extruded by the hydrated seed. This finding characterises a transient but crucial time of crop production around sowing when physical properties of soil surrounding seeds are relevant to stability, germination and plant–microorganism relations.
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Lesovik, Valery S., Evgeny S. Glagolev, Michail Yu Elistratkin, Marina A. Pospelova, and Natalia I. Alfimova. "The Method of Creating and Measuring the Printability of Fine-Grained Concrete." Materials Science Forum 1017 (January 2021): 71–80. http://dx.doi.org/10.4028/www.scientific.net/msf.1017.71.
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One of the factors hindering the normal development of additive construction technologies is the lack of reasonable methods for evaluating the suitability of mixtures for printing. This makes it almost impossible to compare remotely the compositions of different developers, makes it difficult to develop equipment and regulatory documentation, without which it is impossible to complete industrial production. The paper considers the feasibility of introducing the concept of “printability” of compositions and “rheological technological index of mixtures” as a numerical indicator for its evaluation. The design of the device for determining the rheological technological index is described. The developed device has a low cost of production, is linked to standard equipment of construction laboratories and emulates the main types of effects on the mixture during the extrusion process. The effective method for ensuring the printability of fine-grained concretes is considered based on the joint use of traditional plasticizing additives with entrained agents – foaming agents for cellular concretes. The effect of these additives is realized at different scale levels (micro-and mesolevels (cement paste) – traditional superplasticizers; macro-level (fine aggregate) - entrained agents), which together provides high rheological technological indices and effectiveness of mixtures with increased amounts of sand, low W/C ratios and small dosages of these additives. The use of additional mineral or organic rheology modifiers that increase the cost of the mixture is not required in this case. The structural features and basic properties of the developed composites are studied, allowing making comparisons with the solutions of other developers, assessing the prospects of the proposed method of ensuring printability, and outlining directions for its further improvement.
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Hemes, S., G. Desbois, J. L. Urai, M. De Craen, and M. Honty. "Variations in the morphology of porosity in the Boom Clay Formation: insights from 2D high resolution BIB-SEM imaging and Mercury injection Porosimetry." Netherlands Journal of Geosciences - Geologie en Mijnbouw 92, no. 4 (December 2013): 275–300. http://dx.doi.org/10.1017/s0016774600000214.
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AbstractBoom Clay is considered as one of the potential host rocks for the disposal of high level and/or long lived radioactive waste in a geological formation in Belgium (Mol study site, Mol-1 borehole) and the Netherlands. The direct characterisation of the pore space is essential to help understand the transport properties of radionuclides in argillaceous materials.This contribution aims to characterise and compare the morphology of the pore space in different Boom Clay samples, representing end-members with regard to mineralogy (i.e. clay content) and grain-size distribution of this formation. Broad ion beam (BIB) cross-sectioning is combined with SEM imaging of porosity and Mercury injection Porosimetry (MIP) to characterise the variability of the pore space in Boom Clay at the nm- to μm-scale within representative 2D areas and to relate microstructural observations to fluid flow properties of the bulk sample material. Segmented pores in 2D BIB surfaces are classified according to the mineralogy, generating representative datasets of up to 100,000 pores per cross-section.Results show total SEM-resolved porosities of 10-20% and different characteristic mineral phase internal pore morphologies and intra-phase porosities.Most of the nano-porosity resides in the clay matrix. In addition, in the silt-rich samples, larger inter-aggregate pores contribute to a major part of the resolved porosity. Pore-size distributions within the clay matrix suggest power-law behaviour of pore areas with exponents between 1.56-1.74. Mercury injection Porosimetry, with access to pore-throat diameters down to 3.6 nm, shows total interconnected porosities between 27-35 Vol.-%, and the observed hysteresis in the MIP intrusion vs. extrusion curves suggests relatively high pore-body to pore-throat ratios in Boom Clay. The difference between BIB-SEM visible and MIP measured porosities is explained by the resolution limit of the BIB-SEM method, as well as the limited size of the BIB-polished cross-section areas analysed. Compilation of the results provides a conceptual model of the pore network in fine- and coarse-grained samples of Boom Clay, where different mineral phases show characteristic internal porosities and pore morphologies and the overall pore space can be modelled based on the distribution of these mineral phases, as well as the grain-size distribution of the samples investigated.
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Liang, Raymond, Vijay Menon, Miao Lin, Roberta Nowak, Velia M. Fowler, Geoffrey Girnun, and Saghi Ghaffari. "Mitochondrial Regulation Is Essential for Erythroid Nuclear Clearance." Blood 132, Supplement 1 (November 29, 2018): 843. http://dx.doi.org/10.1182/blood-2018-99-120063.
Full textAbstract:
Abstract The terminal steps of red blood cell (RBC) generation involve an extensive cellular remodeling. This encompasses alterations of cellular content through five erythroblast stages that result in the expulsion of the nucleus (enucleation) followed by loss of mitochondria and all other organelles, and a transition to anaerobic glycolysis. Whether there is any link between the erythroid removal of the nucleus and the function of any other organelle including mitochondria remains unknown. Here we show that mitochondria are essential for nuclear clearance. We first demonstrate through high-throughput single-cell imaging and confocal microscopy that as mouse bone marrow erythroblasts mature (Gate 3: TER119+,CD44low, FSClow), mitochondria migrate to one end of the cell, aggregate and trail behind the nucleus as it extrudes from the cell, a prerequisite for enucleation to complete. We further show that mitochondrial localization behind the nucleus has similar kinetics as nuclear polarization. This process is also conserved in mouse fetal liver erythroid cells as well as in primary human CD34+-derived erythroblasts in culture. Notably, kinesin inhibition disrupts mitochondrial motility and localization and reduces significantly erythroblast enucleation rate in the absence of any impact on dynein or tubulin. These results suggest that mitochondria function as necessary chaperones during erythroblast enucleation. Furthermore, mitochondrial activity distinguishes erythroblasts on the verge of enucleation from others at the same erythroblast stage (Gate 3). We show that active mitochondrial respiration facilitates nuclear condensation and is required for nuclear extrusion. To our surprise however, metabolite profiling revealed that late-stage erythroblasts sustain mitochondrial metabolism and subsequent enucleation primarily through extracellular pyruvate but independently of glucose oxidation or anapleorotic reactions of amino acids. 13C-labeled metabolite tracing also confirmed pyruvate incorporation into mitochondria while glycolysis was minimal in orthochromatic erythroblasts. Thus, we provide evidence for the first time of a link between erythroid enucleation and mitochondrial metabolism. The process described establishes a model of mitochondrial compartmentalization within the cell for providing essential metabolites in a precise spatial and temporal manner. These findings are likely to improve the in vitro production of RBC and might be relevant to anemias of congenital mitochondrial disorders and aging. Disclosures No relevant conflicts of interest to declare.
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Ma, Wenjun, Baokun Qi, Rokayya Sami, Lianzhou Jiang, Yang Li, and Hui Wang. "Conformational and Functional Properties of Soybean Proteins Produced by Extrusion-Hydrolysis Approach." International Journal of Analytical Chemistry 2018 (2018): 1–11. http://dx.doi.org/10.1155/2018/9182508.
Full textAbstract:
The conformational and functional changes of soybean protein after a hybrid extrusion-hydrolysis method were evaluated. Three extrusion temperatures (60, 80, and 100°C) were used prior to enzymatic hydrolysis. The hydrolysis degrees, molecular weight profiles, solubilities, surface hydrophobicities, sulphydryl contents, disulfide bound, water holding capacity, emulsion, and foam properties of the protein isolated from the enzyme-hydrolyzed extruded soybeans were analyzed. It shows that extrusion caused significant changes in the hydrophobicity, molecular weight distribution, solubility, surface hydrophobicity, emulsification activity, and stability of the protein. The increase of molecular weights could be attributed to the formation of protein aggregates during extrusion. Extrusion and enzymatic hydrolysis led to a sharp increase in the number of disulfide bonds with a decrease of the sulphydryl group. The water holding capacity and the solubility of protein increased with the increase of extrusion temperature and hydrolysis time. Extrusion improved the emulsifying activity but reduced the emulsifying stability of the recovered proteins. Extrusion improved the foam capacity but reduced the foam stability of the proteins. The data demonstrated that the extrusion-hydrolysis treatment significantly altered the conformational and functional properties of soybean protein, which may be further optimized for the development of new soy protein ingredient with desired functional properties.