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Hyoun-ee Kim - One of the best experts on this subject based on the ideXlab platform.
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Novel Camphene/photopolymer solution as pore-forming agent for photocuring-assisted additive manufacturing of porous ceramics
Journal of the European Ceramic Society, 2021Co-Authors: Gyu-bin Choe, Young Hag Koh, Gyu-nam Kim, Hyun Soon Lee, Hyoun-ee KimAbstract:Abstract This study proposes Camphene/photopolymer solutions as a novel pore-forming agent for the photocuring-assisted additive manufacturing of porous ceramics. Unlike conventional techniques using molten Camphene, solid Camphene can be directly dissolved in the photocurable monomer hexanediol diacrylate (HDDA) at room temperature, which can then crystallize with a dendrite-like morphology based on phase separation at lower temperatures. This unique approach allows alumina suspensions to solidify at ―2 °C and then effectively be photopolymerized using a digital light processing engine, resulting in Camphene-rich crystals surrounded by photopolymerized alumina/HDDA walls. Sintered samples exhibited a highly porous structure, with the pores created after the removal of the Camphene-rich crystals. Two different pore sizes were obtained in the lower and upper regions of a single layer, due to a decrease in the solidification rate along the building direction, although their porosities were similar (∼ 52 vol%). The porous samples exhibited a compressive strength of ∼ 265 MPa.
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design and production of continuously gradient macro microporous calcium phosphate cap scaffolds using ceramic Camphene based 3d extrusion
Materials, 2017Co-Authors: Young Wook Moo, Young Hag Koh, Woo Youl Maeng, Hyoun-ee KimAbstract:This study proposes a new type of calcium phosphate (CaP) scaffolds with a continuously gradient macro/microporous structure using the ceramic/Camphene-based 3D extrusion process. Green filaments with a continuously gradient core/shell structure were successfully produced by extruding a bilayered feedrod comprised of a CaP/Camphene mixture lower part and a pure Camphene upper part. The extruded filaments were then deposited in a controlled manner to construct triangular prisms, followed by the assembly process for the production of CaP scaffolds with a gradient core/shell structure. In addition, a gradient microporous structure was created by heat-treating the green body at 43 °C to induce the overgrowth of Camphene dendrites in the CaP/Camphene walls. The produced CaP scaffold showed a highly macroporous structure within its inner core, where the size of macrochannels increased gradually with an increase in the distance from the outer shell, while relatively larger micropores were created in the outer shell.
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Design and Production of Continuously Gradient Macro/Microporous Calcium Phosphate (CaP) Scaffolds Using Ceramic/Camphene-Based 3D Extrusion.
Materials (Basel Switzerland), 2017Co-Authors: Min Kyung Ahn, Young Wook Moon, Young Hag Koh, Woo Youl Maeng, Hyoun-ee KimAbstract:This study proposes a new type of calcium phosphate (CaP) scaffolds with a continuously gradient macro/microporous structure using the ceramic/Camphene-based 3D extrusion process. Green filaments with a continuously gradient core/shell structure were successfully produced by extruding a bilayered feedrod comprised of a CaP/Camphene mixture lower part and a pure Camphene upper part. The extruded filaments were then deposited in a controlled manner to construct triangular prisms, followed by the assembly process for the production of CaP scaffolds with a gradient core/shell structure. In addition, a gradient microporous structure was created by heat-treating the green body at 43 °C to induce the overgrowth of Camphene dendrites in the CaP/Camphene walls. The produced CaP scaffold showed a highly macroporous structure within its inner core, where the size of macrochannels increased gradually with an increase in the distance from the outer shell, while relatively larger micropores were created in the outer shell.
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calcium phosphate ceramics with continuously gradient macrochannels using three dimensional extrusion of bilayered ceramic Camphene mixture pure Camphene feedrod
Ceramics International, 2016Co-Authors: Young Wook Moo, Young Hag Koh, Woo Youl Maeng, Hyoun-ee KimAbstract:Abstract We herein demonstrate a novel, versatile approach to produce calcium phosphate (CaP) ceramics with continuously gradient macrochannels using three-dimensional extrusion of a bilayered ceramic-Camphene mixture/pure Camphene feedrod. In this technique, the pure Camphene used as the upper part could be preferentially extruded because of the wall slip phenomenon. This enabled the formation of green filaments comprised of a Camphene core surrounded by a ceramic/Camphene shell, where the core/shell thickness ratio increased gradually as extrusion proceeded. CaP ceramics with continuously gradient macrochannels could be successfully produced by three-dimensionally depositing the extruded filaments layer-by-layer. With increasing the distance from the dense bottom layer, macrochannels created after the removal of the Camphene cores via freeze-drying became larger, while the CaP walls became thinner. The local porosity could increase gradually and continuously from the dense bottom and reach up to ~72 vol%.
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novel three dimensional extrusion of multilayered ceramic Camphene mixture for gradient porous ceramics
Journal of the American Ceramic Society, 2016Co-Authors: Ik Ju Choi, Young Hag Koh, Young Wook Moo, Hyoun-ee KimAbstract:This study proposes an innovative way of creating porous ceramics with a unique gradient porous structure using three-dimensional extrusion of a multilayered ceramic/Camphene feed rod, denoted as “3D-Exm”. This 3D-Exm technique utilizes the wall slip phenomenon during the extrusion process, which can create a gradient core/shell structure with a gradual change in the core/shell thickness ratio. In addition, the microstructure of ceramic filaments can be tuned through the use of the Camphene as a pore-forming agent. Porous alumina ceramics produced using a bilayered feed rod comprised of the alumina/Camphene mixtures with the relatively high (ϕH = 40 vol%) and low ceramic contents (ϕL = 10 vol%) showed a gradual change in porosity in the intermediate region between the relatively dense (porosity = ~3 vol%) and highly porous regions (porosity = ~85 vol%).
Young Hag Koh - One of the best experts on this subject based on the ideXlab platform.
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Novel Camphene/photopolymer solution as pore-forming agent for photocuring-assisted additive manufacturing of porous ceramics
Journal of the European Ceramic Society, 2021Co-Authors: Gyu-bin Choe, Young Hag Koh, Gyu-nam Kim, Hyun Soon Lee, Hyoun-ee KimAbstract:Abstract This study proposes Camphene/photopolymer solutions as a novel pore-forming agent for the photocuring-assisted additive manufacturing of porous ceramics. Unlike conventional techniques using molten Camphene, solid Camphene can be directly dissolved in the photocurable monomer hexanediol diacrylate (HDDA) at room temperature, which can then crystallize with a dendrite-like morphology based on phase separation at lower temperatures. This unique approach allows alumina suspensions to solidify at ―2 °C and then effectively be photopolymerized using a digital light processing engine, resulting in Camphene-rich crystals surrounded by photopolymerized alumina/HDDA walls. Sintered samples exhibited a highly porous structure, with the pores created after the removal of the Camphene-rich crystals. Two different pore sizes were obtained in the lower and upper regions of a single layer, due to a decrease in the solidification rate along the building direction, although their porosities were similar (∼ 52 vol%). The porous samples exhibited a compressive strength of ∼ 265 MPa.
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design and production of continuously gradient macro microporous calcium phosphate cap scaffolds using ceramic Camphene based 3d extrusion
Materials, 2017Co-Authors: Young Wook Moo, Young Hag Koh, Woo Youl Maeng, Hyoun-ee KimAbstract:This study proposes a new type of calcium phosphate (CaP) scaffolds with a continuously gradient macro/microporous structure using the ceramic/Camphene-based 3D extrusion process. Green filaments with a continuously gradient core/shell structure were successfully produced by extruding a bilayered feedrod comprised of a CaP/Camphene mixture lower part and a pure Camphene upper part. The extruded filaments were then deposited in a controlled manner to construct triangular prisms, followed by the assembly process for the production of CaP scaffolds with a gradient core/shell structure. In addition, a gradient microporous structure was created by heat-treating the green body at 43 °C to induce the overgrowth of Camphene dendrites in the CaP/Camphene walls. The produced CaP scaffold showed a highly macroporous structure within its inner core, where the size of macrochannels increased gradually with an increase in the distance from the outer shell, while relatively larger micropores were created in the outer shell.
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Design and Production of Continuously Gradient Macro/Microporous Calcium Phosphate (CaP) Scaffolds Using Ceramic/Camphene-Based 3D Extrusion.
Materials (Basel Switzerland), 2017Co-Authors: Min Kyung Ahn, Young Wook Moon, Young Hag Koh, Woo Youl Maeng, Hyoun-ee KimAbstract:This study proposes a new type of calcium phosphate (CaP) scaffolds with a continuously gradient macro/microporous structure using the ceramic/Camphene-based 3D extrusion process. Green filaments with a continuously gradient core/shell structure were successfully produced by extruding a bilayered feedrod comprised of a CaP/Camphene mixture lower part and a pure Camphene upper part. The extruded filaments were then deposited in a controlled manner to construct triangular prisms, followed by the assembly process for the production of CaP scaffolds with a gradient core/shell structure. In addition, a gradient microporous structure was created by heat-treating the green body at 43 °C to induce the overgrowth of Camphene dendrites in the CaP/Camphene walls. The produced CaP scaffold showed a highly macroporous structure within its inner core, where the size of macrochannels increased gradually with an increase in the distance from the outer shell, while relatively larger micropores were created in the outer shell.
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calcium phosphate ceramics with continuously gradient macrochannels using three dimensional extrusion of bilayered ceramic Camphene mixture pure Camphene feedrod
Ceramics International, 2016Co-Authors: Young Wook Moo, Young Hag Koh, Woo Youl Maeng, Hyoun-ee KimAbstract:Abstract We herein demonstrate a novel, versatile approach to produce calcium phosphate (CaP) ceramics with continuously gradient macrochannels using three-dimensional extrusion of a bilayered ceramic-Camphene mixture/pure Camphene feedrod. In this technique, the pure Camphene used as the upper part could be preferentially extruded because of the wall slip phenomenon. This enabled the formation of green filaments comprised of a Camphene core surrounded by a ceramic/Camphene shell, where the core/shell thickness ratio increased gradually as extrusion proceeded. CaP ceramics with continuously gradient macrochannels could be successfully produced by three-dimensionally depositing the extruded filaments layer-by-layer. With increasing the distance from the dense bottom layer, macrochannels created after the removal of the Camphene cores via freeze-drying became larger, while the CaP walls became thinner. The local porosity could increase gradually and continuously from the dense bottom and reach up to ~72 vol%.
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novel three dimensional extrusion of multilayered ceramic Camphene mixture for gradient porous ceramics
Journal of the American Ceramic Society, 2016Co-Authors: Ik Ju Choi, Young Hag Koh, Young Wook Moo, Hyoun-ee KimAbstract:This study proposes an innovative way of creating porous ceramics with a unique gradient porous structure using three-dimensional extrusion of a multilayered ceramic/Camphene feed rod, denoted as “3D-Exm”. This 3D-Exm technique utilizes the wall slip phenomenon during the extrusion process, which can create a gradient core/shell structure with a gradual change in the core/shell thickness ratio. In addition, the microstructure of ceramic filaments can be tuned through the use of the Camphene as a pore-forming agent. Porous alumina ceramics produced using a bilayered feed rod comprised of the alumina/Camphene mixtures with the relatively high (ϕH = 40 vol%) and low ceramic contents (ϕL = 10 vol%) showed a gradual change in porosity in the intermediate region between the relatively dense (porosity = ~3 vol%) and highly porous regions (porosity = ~85 vol%).
Young Wook Moon - One of the best experts on this subject based on the ideXlab platform.
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Design and Production of Continuously Gradient Macro/Microporous Calcium Phosphate (CaP) Scaffolds Using Ceramic/Camphene-Based 3D Extrusion.
Materials (Basel Switzerland), 2017Co-Authors: Min Kyung Ahn, Young Wook Moon, Young Hag Koh, Woo Youl Maeng, Hyoun-ee KimAbstract:This study proposes a new type of calcium phosphate (CaP) scaffolds with a continuously gradient macro/microporous structure using the ceramic/Camphene-based 3D extrusion process. Green filaments with a continuously gradient core/shell structure were successfully produced by extruding a bilayered feedrod comprised of a CaP/Camphene mixture lower part and a pure Camphene upper part. The extruded filaments were then deposited in a controlled manner to construct triangular prisms, followed by the assembly process for the production of CaP scaffolds with a gradient core/shell structure. In addition, a gradient microporous structure was created by heat-treating the green body at 43 °C to induce the overgrowth of Camphene dendrites in the CaP/Camphene walls. The produced CaP scaffold showed a highly macroporous structure within its inner core, where the size of macrochannels increased gradually with an increase in the distance from the outer shell, while relatively larger micropores were created in the outer shell.
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Novel Three-Dimensional Extrusion of Multilayered Ceramic/Camphene Mixture for Gradient Porous Ceramics
Journal of the American Ceramic Society, 2015Co-Authors: Ik Jun Choi, Young Wook Moon, Young Hag Koh, Hyoun-ee KimAbstract:This study proposes an innovative way of creating porous ceramics with a unique gradient porous structure using three-dimensional extrusion of a multilayered ceramic/Camphene feed rod, denoted as “3D-Exm”. This 3D-Exm technique utilizes the wall slip phenomenon during the extrusion process, which can create a gradient core/shell structure with a gradual change in the core/shell thickness ratio. In addition, the microstructure of ceramic filaments can be tuned through the use of the Camphene as a pore-forming agent. Porous alumina ceramics produced using a bilayered feed rod comprised of the alumina/Camphene mixtures with the relatively high (ϕH = 40 vol%) and low ceramic contents (ϕL = 10 vol%) showed a gradual change in porosity in the intermediate region between the relatively dense (porosity = ~3 vol%) and highly porous regions (porosity = ~85 vol%).
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Porous alumina ceramic scaffolds with biomimetic macro/micro-porous structure using three-dimensional (3-D) ceramic/Camphene-based extrusion
Ceramics International, 2015Co-Authors: Young Wook Moon, Ik Jun Choi, Young Hag Koh, Hyoun-ee KimAbstract:Abstract This study demonstrates the versatility of 3-dimensional ceramic/Camphene-based extrusion (3D-Ex) using a frozen alumina/Camphene body as a feedstock for the production of porous alumina scaffolds with a biomimetic macro/micro-porous structure. Three-dimensionally interconnected macropores were constructed through the deposition of frozen alumina/Camphene filaments at a stacking sequence of 0°/90°, while aligned micropores were created in alumina frameworks as the replica of Camphene dendrites that had been extensively elongated by the extrusion of a frozen alumina/Camphene body. The macro/micro-porous structure and compressive strength of porous alumina scaffolds could be tailored by adjusting initial alumina content in alumina/Camphene slurries.
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Macroporous alumina scaffolds consisting of highly microporous hollow filaments using three-dimensional ceramic/Camphene-based co-extrusion
Journal of the European Ceramic Society, 2015Co-Authors: Young Wook Moon, Ik Jun Choi, Young Hag Koh, Hyoun-ee KimAbstract:Abstract This study proposes a novel type of macroporous ceramic scaffolds, which are comprised of hollow tubular filaments with a highly microporous structure, using 3-dimensional ceramic/Camphene-based co-extrusion (3D-CoEx). The use of an initial feedrod, comprised of a Camphene core and an alumina/Camphene shell, enabled the construction of hollow tubular frameworks and micropores through the removal of the Camphene phase. The produced scaffolds showed 3-dimensionally interconnected macropores with dimensions of ∼250–300 μm × 400–550 μm, which were surrounded by hollow alumina filaments (∼500 μm in diameter) featuring a number of micropores (several tens of microns in size). This unique macro/micro-porous structure could achieve a combination of both the reasonably high compressive strength of ∼5.4 MPa and very high porosity of 86 vol%. In addition, the final mechanical properties and overall porosity of the porous alumina scaffolds could be fine-tuned by adjusting initial alumina content in the alumina/Camphene.
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three dimensional ceramic Camphene based coextrusion for unidirectionally macrochanneled alumina ceramics with controlled porous walls
Journal of the American Ceramic Society, 2014Co-Authors: Young Wook Moon, Kwan Ha Shin, Hyun Do JungAbstract:We report the utility of three-dimensional ceramic/Camphene-based coextrusion, newly developed in this study, for the production of unidirectionally macrochanneled alumina ceramics with three-dimensionally interconnected porous alumina walls. In this technique, a continuous ceramic/Camphene filament with a diameter of 1 mm, comprised of a pure Camphene core and a frozen alumina/Camphene shell, was produced by the coextrusion process and then deposited in a layer-by-layer sequence using a computer-controlled 3-axis moving table. Unidirectionally aligned macrochannels (~400 μm in diameter) and three-dimensionally interconnected pores (several tens of micrometers in size) in the alumina walls were created by removing the Camphene core and the Camphene dendrites formed in the alumina/Camphene region, respectively. The sample showed much higher compressive strength in the macrochannel direction than in the perpendicular direction. In addition, the compressive strength of the sample could increase with an increase in initial alumina content owing to a decrease in the total porosity.
Rodney Croteau - One of the best experts on this subject based on the ideXlab platform.
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monoterpene synthases from common sage salvia officinalis cdna isolation characterization and functional expression of sabinene synthase 1 8 cineole synthase and bornyl diphosphate synthase
Journal of Biological Chemistry, 1998Co-Authors: Mitchell L Wise, Thomas J Savage, Eva Katahira, Rodney CroteauAbstract:Abstract Common sage (Salvia officinalis) produces an extremely broad range of cyclic monoterpenes bearing diverse carbon skeletons, including members of thep-menthane (1,8-cineole), pinane (α- and β-pinene), thujane (isothujone), camphane (Camphene), and bornane (camphor) families. An homology-based polymerase chain reaction cloning strategy was developed and used to isolate the cDNAs encoding three multiproduct monoterpene synthases from this species that were functionally expressed in Escherichia coli. The heterologously expressed synthases produce (+)-bornyl diphosphate, 1,8-cineole, and (+)-sabinene, respectively, as their major products from geranyl diphosphate. The bornyl diphosphate synthase also produces significant amounts of (+)-α-pinene, (+)-Camphene, and (±)-limonene. The 1,8-cineole synthase produces significant amounts of (+)- and (−)-α-pinene, (+)- and (−)-β-pinene, myrcene and (+)-sabinene, and the (+)-sabinene synthase produces significant quantities of γ-terpinene and terpinolene. All three enzymes appear to be translated as preproteins bearing an amino-terminal plastid targeting sequence, consistent with the plastidial origin of monoterpenes in plants. Deduced sequence analysis and size exclusion chromatography indicate that the recombinant bornyl diphosphate synthase is a homodimer, whereas the other two recombinant enzymes are monomeric, consistent with the size and subunit architecture of their native enzyme counterparts. The distribution and stereochemistry of the products generated by the recombinant (+)-bornyl diphosphate synthase suggest that this enzyme might represent both (+)-bornyl diphosphate synthase and (+)-pinene synthase which were previously assumed to be distinct enzymes.
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Monoterpene Synthases from Common Sage (Salvia officinalis) cDNA ISOLATION, CHARACTERIZATION, AND FUNCTIONAL EXPRESSION OF (+)-SABINENE SYNTHASE, 1,8-CINEOLE SYNTHASE, AND (+)-BORNYL DIPHOSPHATE SYNTHASE
Journal of Biological Chemistry, 1998Co-Authors: Mitchell L Wise, Thomas J Savage, Eva Katahira, Rodney CroteauAbstract:Abstract Common sage (Salvia officinalis) produces an extremely broad range of cyclic monoterpenes bearing diverse carbon skeletons, including members of thep-menthane (1,8-cineole), pinane (α- and β-pinene), thujane (isothujone), camphane (Camphene), and bornane (camphor) families. An homology-based polymerase chain reaction cloning strategy was developed and used to isolate the cDNAs encoding three multiproduct monoterpene synthases from this species that were functionally expressed in Escherichia coli. The heterologously expressed synthases produce (+)-bornyl diphosphate, 1,8-cineole, and (+)-sabinene, respectively, as their major products from geranyl diphosphate. The bornyl diphosphate synthase also produces significant amounts of (+)-α-pinene, (+)-Camphene, and (±)-limonene. The 1,8-cineole synthase produces significant amounts of (+)- and (−)-α-pinene, (+)- and (−)-β-pinene, myrcene and (+)-sabinene, and the (+)-sabinene synthase produces significant quantities of γ-terpinene and terpinolene. All three enzymes appear to be translated as preproteins bearing an amino-terminal plastid targeting sequence, consistent with the plastidial origin of monoterpenes in plants. Deduced sequence analysis and size exclusion chromatography indicate that the recombinant bornyl diphosphate synthase is a homodimer, whereas the other two recombinant enzymes are monomeric, consistent with the size and subunit architecture of their native enzyme counterparts. The distribution and stereochemistry of the products generated by the recombinant (+)-bornyl diphosphate synthase suggest that this enzyme might represent both (+)-bornyl diphosphate synthase and (+)-pinene synthase which were previously assumed to be distinct enzymes.
Mustafa Gündüz - One of the best experts on this subject based on the ideXlab platform.
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Solid–liquid interfacial energy of Camphene
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 1999Co-Authors: B. Bayender, Necmettin Maraşlı, Emin Çadırlı, Mustafa GündüzAbstract:The Gibbs‐Thomson coefficient and the solid‐liquid interfacial energy for Camphene have been measured to be (8.5890.96) 10 8 K m and (4.4390.49)10 3 Jm 2 , respectively, by a direct method. The grain boundary energy of Camphene has also been calculated to be (8.3690.92)10 3 Jm 2 from the observed grain boundary groove shapes. © 1999 Elsevier Science S.A.
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solid liquid interfacial energy of Camphene
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 1999Co-Authors: B. Bayender, Necmettin Maraşlı, Emin Çadırlı, Mustafa GündüzAbstract:The Gibbs‐Thomson coefficient and the solid‐liquid interfacial energy for Camphene have been measured to be (8.5890.96) 10 8 K m and (4.4390.49)10 3 Jm 2 , respectively, by a direct method. The grain boundary energy of Camphene has also been calculated to be (8.3690.92)10 3 Jm 2 from the observed grain boundary groove shapes. © 1999 Elsevier Science S.A.