Environmental and energy conservation pressure has led to a dramatic increase in the need for economically feasible lightweight materials that can be better substitutes for non-biodegradable materials in reinforced composites. In this study, the mechanical and thermal properties of polyester resin composites hybridized with a blend of untreated and alkali treated sisal (Agave sisalana) and cattail (Typha angustifolia) fibers were evaluated. Composites were fabricated by a hand lay-up technique at an optimal hybrid fiber weight fraction of 20 wt% and a constant sisal/cattail fiber blend ratio of 75/25. Flexural, tensile, compressive and impact strengths and moduli, as well as thermal conductivity of the composites, were evaluated following ASTM and ISO test methods. Analytical results indicated that alkali pre-treatment of the fibers enhanced the mechanical properties of the hybrid polyester composites though only marginal differences were recorded in the thermal conductivity of the composites fabricated with treated and untreated fiber blends. Morphological examination revealed that the major failure modes were fiber pull-outs and fiber fracture in composites fabricated with untreated and treated fiber blends, respectively. The composites produced could find non-structural applications as ceiling boards, electronic and food packaging materials but their properties such as wettability, crystallinity, flammability and other thermal properties need to be further investigated.
{"title":"Effects of alkali treatment on the mechanical and thermal properties of sisal/cattail polyester commingled composites","authors":"Silas Mogaka Mbeche, Timothy Omara","doi":"10.7717/peerj-matsci.5","DOIUrl":"https://doi.org/10.7717/peerj-matsci.5","url":null,"abstract":"Environmental and energy conservation pressure has led to a dramatic increase in the need for economically feasible lightweight materials that can be better substitutes for non-biodegradable materials in reinforced composites. In this study, the mechanical and thermal properties of polyester resin composites hybridized with a blend of untreated and alkali treated sisal (Agave sisalana) and cattail (Typha angustifolia) fibers were evaluated. Composites were fabricated by a hand lay-up technique at an optimal hybrid fiber weight fraction of 20 wt% and a constant sisal/cattail fiber blend ratio of 75/25. Flexural, tensile, compressive and impact strengths and moduli, as well as thermal conductivity of the composites, were evaluated following ASTM and ISO test methods. Analytical results indicated that alkali pre-treatment of the fibers enhanced the mechanical properties of the hybrid polyester composites though only marginal differences were recorded in the thermal conductivity of the composites fabricated with treated and untreated fiber blends. Morphological examination revealed that the major failure modes were fiber pull-outs and fiber fracture in composites fabricated with untreated and treated fiber blends, respectively. The composites produced could find non-structural applications as ceiling boards, electronic and food packaging materials but their properties such as wettability, crystallinity, flammability and other thermal properties need to be further investigated.","PeriodicalId":219314,"journal":{"name":"PeerJ Materials Science","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124846139","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Liew Chien Go, D. Depan, W. Holmes, August A. Gallo, K. Knierim, Tre Bertrand, R. Hernandez
Extracellular polymeric substances (EPS) extracted from waste activated sludge (WAS) have previously shown its potential in corrosion inhibition. The aim of this study is to design a synthetic EPS formulation as a surrogate of natural WAS EPS to overcome the corrosion inhibition inconsistency in WAS EPS. The adsorption behavior of the designed inhibitor was studied by kinetic and thermodynamic analyses. Synthetic EPS is a bio-inspired material that was formulated based on the most typical chemical compositions of natural WAS EPS, that is, proteins, carbohydrates, humic substances, nucleic acids, and uronic acids, which was not optimized for corrosion inhibition performance. It is a mixture of glutamic acid, carboxymethylcellulose, humic acid, thymine, and alginic acid. Its corrosion inhibition performance was tested with carbon steel in 3.64% NaCl saturated with CO2, using the potentiodynamic polarization scanning technique. The resulted electrochemical parameters were used to evaluate the empirical corrosion kinetic and thermodynamic adsorption parameters. Addition of synthetic EPS showed significant decrease in corrosion rate as compared to the control. The inhibition efficiency improved with increasing inhibitor concentration and temperature. The optimum performance was 94% with 204 mg/L of inhibitor applied at 70 °C (343 K). The inhibition performance was controlled by both the concentration of inhibitor and temperature. Chemisorption of the inhibitor molecules contributed to the overall inhibition performance, reducing the contact of metal with the corrosive environment, thus, slowing down the overall corrosion rate.
{"title":"Kinetic and thermodynamic analyses of the corrosion inhibition of synthetic extracellular polymeric substances","authors":"Liew Chien Go, D. Depan, W. Holmes, August A. Gallo, K. Knierim, Tre Bertrand, R. Hernandez","doi":"10.7717/peerj-matsci.4","DOIUrl":"https://doi.org/10.7717/peerj-matsci.4","url":null,"abstract":"\u0000\u0000Extracellular polymeric substances (EPS) extracted from waste activated sludge (WAS) have previously shown its potential in corrosion inhibition. The aim of this study is to design a synthetic EPS formulation as a surrogate of natural WAS EPS to overcome the corrosion inhibition inconsistency in WAS EPS. The adsorption behavior of the designed inhibitor was studied by kinetic and thermodynamic analyses.\u0000\u0000\u0000\u0000Synthetic EPS is a bio-inspired material that was formulated based on the most typical chemical compositions of natural WAS EPS, that is, proteins, carbohydrates, humic substances, nucleic acids, and uronic acids, which was not optimized for corrosion inhibition performance. It is a mixture of glutamic acid, carboxymethylcellulose, humic acid, thymine, and alginic acid. Its corrosion inhibition performance was tested with carbon steel in 3.64% NaCl saturated with CO2, using the potentiodynamic polarization scanning technique. The resulted electrochemical parameters were used to evaluate the empirical corrosion kinetic and thermodynamic adsorption parameters.\u0000\u0000\u0000\u0000Addition of synthetic EPS showed significant decrease in corrosion rate as compared to the control. The inhibition efficiency improved with increasing inhibitor concentration and temperature. The optimum performance was 94% with 204 mg/L of inhibitor applied at 70 °C (343 K). The inhibition performance was controlled by both the concentration of inhibitor and temperature. Chemisorption of the inhibitor molecules contributed to the overall inhibition performance, reducing the contact of metal with the corrosive environment, thus, slowing down the overall corrosion rate.\u0000","PeriodicalId":219314,"journal":{"name":"PeerJ Materials Science","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123768383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-12-23DOI: 10.26434/chemrxiv.11388678.v1
Nicholas Marshall, Andrés Rodríguez
Cross-coupling at aryl halide thin films has been well-established as a technique for the surface-initiated Kumada catalyst transfer polymerization (SI-KCTP), used to produce covalently bound conjugated polymer thin films. In this work, we report that the spontaneous grafting of 4-iodobenzenediazonium tetrafluoroborate on gold substrates creates a durable iodoarene layer which is effective as a substrate for cross-coupling reactions including SI-KCTP. Using cyclic voltammetry of a surface-coupled ferrocene terminating agent, we have measured initiator surface coverage produced by oxidative addition of Pd(t-Bu3P)2 and estimated the rate constant of the termination reaction in the SI-KCTP system with 2-chloromagnesio-5-bromothiophene and Pd(t-Bu3P)2. We used this system to prepare uniform polythiophene thin films averaging 90 nm in thickness.
{"title":"Cross-coupling polymerization at iodophenyl thin films prepared by spontaneous grafting of a diazonium salt","authors":"Nicholas Marshall, Andrés Rodríguez","doi":"10.26434/chemrxiv.11388678.v1","DOIUrl":"https://doi.org/10.26434/chemrxiv.11388678.v1","url":null,"abstract":"Cross-coupling at aryl halide thin films has been well-established as a technique for the surface-initiated Kumada catalyst transfer polymerization (SI-KCTP), used to produce covalently bound conjugated polymer thin films. In this work, we report that the spontaneous grafting of 4-iodobenzenediazonium tetrafluoroborate on gold substrates creates a durable iodoarene layer which is effective as a substrate for cross-coupling reactions including SI-KCTP. Using cyclic voltammetry of a surface-coupled ferrocene terminating agent, we have measured initiator surface coverage produced by oxidative addition of Pd(t-Bu3P)2 and estimated the rate constant of the termination reaction in the SI-KCTP system with 2-chloromagnesio-5-bromothiophene and Pd(t-Bu3P)2. We used this system to prepare uniform polythiophene thin films averaging 90 nm in thickness.","PeriodicalId":219314,"journal":{"name":"PeerJ Materials Science","volume":" 5","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132124869","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
H. Ferreira, E. Lopes, José F. Malta, L. Ferreira, M. H. Casimiro, Luís F. Santos, Manuel F. C. Pereira, António Pereira Gonçalves
Vaesite, a nickel chalcogenide with NiS2 formula, has been synthetized and studied by theoretical and experimental methods. NiS2 was prepared by solid-state reaction under vacuum and densified by hot-pressing, at different consolidation conditions. Dense single-phase pellets (relative densities >94%) were obtained, without significant lattice distortions for different hot-pressing conditions. The thermal stability of NiS2 was studied by thermogravimetric analysis. Both as-synthetized and hot-pressed NiS2 have a single phase nature, although some hot-pressed samples had traces of the sulfur deficient phase, Ni1-xS (<1%vol), due to the strong desulfurization at T > 340 °C. The electronic band structure and density of states were calculated by Density Functional Theory (DFT), indicating a metallic behavior. However, the electronic transport measurements showed p-type semiconductivity for bulk NiS2, verifying its characteristic behavior has a Mott insulator. The consolidation conditions strongly influence the electronic properties, with the best room-temperature Seebeck coefficient, electrical resistivity and power factor being 182 µVK−1, 2,257 µΩ m and 14.1 µWK−2 m−1, respectively, pointing this compound as a good starting point for a new family of thermoelectric materials.
{"title":"Preparation, thermal stability and electrical transport properties of vaesite, NiS2","authors":"H. Ferreira, E. Lopes, José F. Malta, L. Ferreira, M. H. Casimiro, Luís F. Santos, Manuel F. C. Pereira, António Pereira Gonçalves","doi":"10.7717/PEERJ-MATSCI.2","DOIUrl":"https://doi.org/10.7717/PEERJ-MATSCI.2","url":null,"abstract":"Vaesite, a nickel chalcogenide with NiS2 formula, has been synthetized and studied by theoretical and experimental methods. NiS2 was prepared by solid-state reaction under vacuum and densified by hot-pressing, at different consolidation conditions. Dense single-phase pellets (relative densities >94%) were obtained, without significant lattice distortions for different hot-pressing conditions. The thermal stability of NiS2 was studied by thermogravimetric analysis. Both as-synthetized and hot-pressed NiS2 have a single phase nature, although some hot-pressed samples had traces of the sulfur deficient phase, Ni1-xS (<1%vol), due to the strong desulfurization at T > 340 °C. The electronic band structure and density of states were calculated by Density Functional Theory (DFT), indicating a metallic behavior. However, the electronic transport measurements showed p-type semiconductivity for bulk NiS2, verifying its characteristic behavior has a Mott insulator. The consolidation conditions strongly influence the electronic properties, with the best room-temperature Seebeck coefficient, electrical resistivity and power factor being 182 µVK−1, 2,257 µΩ m and 14.1 µWK−2 m−1, respectively, pointing this compound as a good starting point for a new family of thermoelectric materials.","PeriodicalId":219314,"journal":{"name":"PeerJ Materials Science","volume":"127 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128424348","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dominik M. Loy, P. Klein, R. Krzysztoń, Ulrich Lächelt, J. Rädler, E. Wagner
Therapeutic nucleic acids provide versatile treatment options for hereditary or acquired diseases. Ionic complexes with basic polymers are frequently used to facilitate nucleic acid’s transport to intracellular target sites. Usually, these polyplexes are prepared manually by mixing two components: polyanionic nucleic acids and polycations. However, parameters such as internal structure, size, polydispersity and surface charge of the complexes sensitively affect pharmaceutical efficiency. Hence a controlled assembly is of paramount importance in order to ensure high product quality. In the current study, we present a microfluidic platform for controlled, sequential formulation of polyplexes. We use oligo-amidoamines (termed “oligomers”) with precise molecular weight and defined structure due to their solid phase supported synthesis. The assembly of the polyplexes was performed in a microfluidic chip in two steps employing a design of two successive Y junctions: first, siRNA and core oligomers were assembled into core polyplexes. These core oligomers possess compacting, stabilizing, and endosomal escape mediating motifs. Second, new functional motifs were mixed to the core particles and integrated into the core polyplex. The iterative assembly formed multi-component polyplexes in a highly controlled manner and enabled us to investigate structure-function relationships. We chose nanoparticle shielding polyethylene glycol (PEG) and cell targeting folic acid (termed “PEG-ligands”) as functional components. The PEG-ligands were coupled to lipid anchor oligomers via strain promoted azide—alkyne click chemistry. The lipid anchors feature four cholanic acids for inserting various PEG-ligands into the core polyplex by non-covalent hydrophobic interactions. These core—lipid anchor—PEG-ligand polyplexes containing folate as cell binding ligand were used to determine the optimal PEG-ligand length for transfecting folate receptor-expressing KB cells in vitro. We found that polyplexes with 20 mol % PEG-ligands (relative to ncore oligomer) showed optimal siRNA mediated gene knock-down when containing defined PEG domains of in sum 24 and 36 ethylene oxide repetitions, 12 EOs each from the lipid anchor and 12 or 24 EOs from the PEG-ligand, respectively. These results confirm that transfection efficiency depends on the linker length and stoichiometry and are consistent with previous findings using core—PEG-ligand polyplexes formed by click modification of azide-containing core polyplexes with aforementioned PEG-ligands. Hence, successive microfluidic assembly might be a potentially powerful route to create defined multi-component polyplexes with reduced batch-to-batch variability.
{"title":"A microfluidic approach for sequential assembly of siRNA polyplexes with a defined structure-activity relationship","authors":"Dominik M. Loy, P. Klein, R. Krzysztoń, Ulrich Lächelt, J. Rädler, E. Wagner","doi":"10.7717/PEERJ-MATSCI.1","DOIUrl":"https://doi.org/10.7717/PEERJ-MATSCI.1","url":null,"abstract":"Therapeutic nucleic acids provide versatile treatment options for hereditary or acquired diseases. Ionic complexes with basic polymers are frequently used to facilitate nucleic acid’s transport to intracellular target sites. Usually, these polyplexes are prepared manually by mixing two components: polyanionic nucleic acids and polycations. However, parameters such as internal structure, size, polydispersity and surface charge of the complexes sensitively affect pharmaceutical efficiency. Hence a controlled assembly is of paramount importance in order to ensure high product quality. In the current study, we present a microfluidic platform for controlled, sequential formulation of polyplexes. We use oligo-amidoamines (termed “oligomers”) with precise molecular weight and defined structure due to their solid phase supported synthesis. The assembly of the polyplexes was performed in a microfluidic chip in two steps employing a design of two successive Y junctions: first, siRNA and core oligomers were assembled into core polyplexes. These core oligomers possess compacting, stabilizing, and endosomal escape mediating motifs. Second, new functional motifs were mixed to the core particles and integrated into the core polyplex. The iterative assembly formed multi-component polyplexes in a highly controlled manner and enabled us to investigate structure-function relationships. We chose nanoparticle shielding polyethylene glycol (PEG) and cell targeting folic acid (termed “PEG-ligands”) as functional components. The PEG-ligands were coupled to lipid anchor oligomers via strain promoted azide—alkyne click chemistry. The lipid anchors feature four cholanic acids for inserting various PEG-ligands into the core polyplex by non-covalent hydrophobic interactions. These core—lipid anchor—PEG-ligand polyplexes containing folate as cell binding ligand were used to determine the optimal PEG-ligand length for transfecting folate receptor-expressing KB cells in vitro. We found that polyplexes with 20 mol % PEG-ligands (relative to ncore oligomer) showed optimal siRNA mediated gene knock-down when containing defined PEG domains of in sum 24 and 36 ethylene oxide repetitions, 12 EOs each from the lipid anchor and 12 or 24 EOs from the PEG-ligand, respectively. These results confirm that transfection efficiency depends on the linker length and stoichiometry and are consistent with previous findings using core—PEG-ligand polyplexes formed by click modification of azide-containing core polyplexes with aforementioned PEG-ligands. Hence, successive microfluidic assembly might be a potentially powerful route to create defined multi-component polyplexes with reduced batch-to-batch variability.","PeriodicalId":219314,"journal":{"name":"PeerJ Materials Science","volume":"58 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122838852","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Saylor, Peter L. Wang, M. Bevelhimer, P. Lloyd, Jesse Goodwin, R. Laughter, David Young, Dustin Sterling, Paritosh Mhatre, C. Atkins, B. Post
Biomimetic model organisms could be useful surrogates for live animals in many applications if the models have sufficient biofidelity. One such application is for use in field and laboratory tests of fish mortality associated with passage through hydropower turbines. Laboratory trials suggest that blade strikes are especially injurious and often causes mortality when fish are struck by thinner blades moving at higher velocities. Dose-response relationships have been created from these data, but the exact relationship between fish mortality and the actual forces enacted on fish during simulated blade strike testing remains unknown. Here, we describe the methods used to create a prototype biomimetic model fish composed of ballistic gelatin and covered with a surrogate skin to better approximate the biomechanical properties of a fish body. Frozen fish were scanned with high-fidelity laser scanners, and a 3D-printed, reusable mold was created from which to cast our gelatin model. Computed tomography scan data, imaged directly or taken from online data repositories, were also successfully used to create CAD models for use in additive manufacturing of molds. One 3-axis accelerometer was embedded into the gelatin to compare accelerometer data to dose-response data from previous laboratory research on live fish. The resulting model (i.e., Gelfish) had a statistically indistinguishable tissue durometer to that of real fish tissue and preliminary blade strike impact testing suggested its overall flexibility was similar to that of live fish. Gelfish was designed with biofidelity as its guiding principle and our results suggest initial experimentation was successful. Future research will include replication of initial Gelfish test results, quantitative measurement of model flexibility relative to real fish, and inclusion of surrogate skeletal structures to enhance biofidelity. Use of more sophisticated sensors would also better quantify the physical forces of blade strike impact and help determine how said forces correlate with rates of mortality observed during tests on live fish.
{"title":"Creation of a prototype biomimetic fish to better understand impact trauma caused by hydropower turbine blade strikes","authors":"R. Saylor, Peter L. Wang, M. Bevelhimer, P. Lloyd, Jesse Goodwin, R. Laughter, David Young, Dustin Sterling, Paritosh Mhatre, C. Atkins, B. Post","doi":"10.7717/peerj-matsci.16","DOIUrl":"https://doi.org/10.7717/peerj-matsci.16","url":null,"abstract":"Biomimetic model organisms could be useful surrogates for live animals in many applications if the models have sufficient biofidelity. One such application is for use in field and laboratory tests of fish mortality associated with passage through hydropower turbines. Laboratory trials suggest that blade strikes are especially injurious and often causes mortality when fish are struck by thinner blades moving at higher velocities. Dose-response relationships have been created from these data, but the exact relationship between fish mortality and the actual forces enacted on fish during simulated blade strike testing remains unknown. Here, we describe the methods used to create a prototype biomimetic model fish composed of ballistic gelatin and covered with a surrogate skin to better approximate the biomechanical properties of a fish body. Frozen fish were scanned with high-fidelity laser scanners, and a 3D-printed, reusable mold was created from which to cast our gelatin model. Computed tomography scan data, imaged directly or taken from online data repositories, were also successfully used to create CAD models for use in additive manufacturing of molds. One 3-axis accelerometer was embedded into the gelatin to compare accelerometer data to dose-response data from previous laboratory research on live fish. The resulting model (i.e., Gelfish) had a statistically indistinguishable tissue durometer to that of real fish tissue and preliminary blade strike impact testing suggested its overall flexibility was similar to that of live fish. Gelfish was designed with biofidelity as its guiding principle and our results suggest initial experimentation was successful. Future research will include replication of initial Gelfish test results, quantitative measurement of model flexibility relative to real fish, and inclusion of surrogate skeletal structures to enhance biofidelity. Use of more sophisticated sensors would also better quantify the physical forces of blade strike impact and help determine how said forces correlate with rates of mortality observed during tests on live fish.","PeriodicalId":219314,"journal":{"name":"PeerJ Materials Science","volume":"562 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122641299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：