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Mahshid Kharaziha - One of the best experts on this subject based on the ideXlab platform.
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combinational processing of 3d printing and electrospinning of hierarchical poly lactic acid gelatin Forsterite scaffolds as a biocomposite mechanical and biological assessment
Materials & Design, 2017Co-Authors: Ehsan Foroozmehr, Saman Naghieh, Mohsen Badrossamay, Mahshid KharazihaAbstract:Abstract In this research, hierarchical scaffolds including poly(lactic acid) (PLA) micro struts and nanocomposite gelatin-Forsterite fibrous layers were developed using fused deposition modeling (FDM) and electrospinning (ES), respectively. Briefly, geometrically various groups of pure PLA scaffolds (interconnected pores of 230 to 390 μm) were fabricated using FDM technique. After mechanical evaluation, ES technique was utilized to develop gelatin-Forsterite nanofibrous layer. To study these scaffolds, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, and uniaxial compression tests were performed. Furthermore, bioactivity of the scaffolds was evaluated by immersing in the simulated body fluid and apatite formation on the surface of the scaffolds was investigated. Results depicted that elastic modulus of PLA/gelatin-Forsterite scaffolds, fabricated by a combinational approach, was significantly higher than that of pure one (about 52%). SEM images showed the formation of calcium phosphate-like precipitates on the surface of these scaffolds, confirming the effects of nanocomposite fibrous layer on the improved bioactivity of the scaffolds. Regarding the obtained biological as well as mechanical properties, the developed bio-composite scaffolds can be used as a biocompatible candidate for bone tissue regeneration.
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electrochemical and in vitro bioactivity of nanocomposite gelatin Forsterite coatings on aisi 316 l stainless steel
Progress in Organic Coatings, 2017Co-Authors: R Torkaman, Mahshid Kharaziha, Sorour Darvishi, M Jokar, Maryam KarbasiAbstract:Abstract AISI 316L stainless steel has been widely considered as implant materials in biomedical applications owing to its low cost and superior strength. However, its weak corrosion resistance due to the release of nickel, chromate and molybdenum ions as well as its inert nature limits its clinical application specifically long-standing performances. The aim of this study was to prepare and characterize gelatin-Forsterite (Mg2SiO4) nanocomposite coatings consisting of various amounts of Forsterite nanopowder (0, 1, 2.5 and 5 wt.%) on AISI 316L substrate in order to improve simultaneously corrosion resistance and in vitro bioactivity. Nanocomposite gelatin-Forsterite coatings were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy and X-ray diffraction. Furthermore, the bioactivity of gelatin-Forsterite coated specimens were evaluated via soaking in simulated body fluid (SBF) for 28 days at 37 °C. Results demonstrated the formation of crack-free and homogeneous coatings without any observable defect and pore. The surface roughness and adhesion strength of the coatings enhanced with increasing Forsterite content. Moreover, the corrosion evaluation considered by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) demonstrated that compered to unmodified AISI 316L substrate, the corrosion resistance of gelatin-Forsterite nanocomposite-coated substrates significantly improved. Moreover, nanocomposite coatings were able to persist severe localized corrosion in physiological solution indicating their long-term biostability. Moreover, the formation of bone-like apatite layer on the nanocomposite-coated samples was observed in SBF, which might be helpful to integrate with host tissue. Overall, it is anticipated that the novel proposed nanocomposite coatings of gelatin-Forsterite might be potentially useful for orthopedic implants.
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effects of surface modification on the mechanical and structural properties of nanofibrous poly e caprolactone Forsterite scaffold for tissue engineering applications
Materials Science and Engineering: C, 2013Co-Authors: Mahshid Kharaziha, M H Fathi, Hossein EdrisAbstract:Composite scaffolds consisting of polymers reinforced with ceramic nanoparticles are widely applied for hard tissue engineering. However, due to the incompatible polarity of ceramic nanoparticles with polymers, they tend to agglomerate in the polymer matrix which results in undesirable effects on the integral properties of composites. In this research, Forsterite (Mg2SiO4) nanoparticles was surface esterified by dodecyl alcohol and nanofibrous poly(e-caprolactone)(PCL)/modified Forsterite scaffolds were developed through electrospinning technique. The aim of this research was to investigate the properties of surface modified Forsterite nanopowder and PCL/modified Forsterite scaffolds, before and after hydrolytic treatment, as well as the cellular attachment and proliferation. Results demonstrated that surface modification of nanoparticles significantly enhanced the tensile strength and toughness of scaffolds upon 1.5- and 4-folds compared to unmodified samples, respectively, due to improved compatibility between matrix and filler. Hydrolytic treatment of scaffolds also modified the bioactivity and cellular attachment and proliferation due to greatly enhanced hydrophilicity of the Forsterite nanoparticles after this process compared to surface modified samples. Results suggested that surface modification of Forsterite nanopowder and hydrolytic treatment of the developed scaffolds were effective approaches to address the issues in the formation of composite fibers and resulted in development of bioactive composite scaffolds with ideal mechanical and structural properties for bone tissue engineering applications.
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preparation and characterization of polycaprolactone Forsterite nanocomposite porous scaffolds designed for bone tissue regeneration
Composites Science and Technology, 2012Co-Authors: Mani Diba, Mahshid Kharaziha, M H Fathi, Mazaher Gholipourmalekabadi, Ali SamadikuchaksaraeiAbstract:Abstract Biocomposite scaffolds made from polymers and bioceramics can provide the mechanical structure necessary for osteoinductivity in the growth of new bone. The aim of this research was to investigate the properties of a novel nanocomposite scaffold made from a combination of polycaprolactone (PCL) and Forsterite nanopowder which could find use in bone tissue engineering applications. The scaffold itself was fabricated by a method of solvent casting and particle leaching. The effect of Forsterite content on the mechanical properties, bioactivity, biodegradability, and cytotoxicity of the scaffolds was investigated. Significant improvement in the mechanical properties was observed in the nanocomposite scaffolds as compared to that seen in the pure PCL scaffolds. Bioactivity was also observed in the nanocomposite scaffolds, a trait which was not present in the pure PCL scaffolds. Biodegradation assay indicated that the addition of Forsterite nanopowder could modulate the degradation rate of PCL. In vitro tests of cytotoxicity and osteoblast proliferation showed that the nanocomposite scaffolds were non-cytotoxic, thereby allowing cells to adhere, grow, and proliferate on the surface of these scaffolds. The results obtained in this experiment suggest that the combination of PCL with Forsterite nanopowder can be used to form scaffolds suitable for use in bone tissue engineering. The exact material behavior required can be adjusted through variation of the ratio between PCL and Forsterite nanopowder used to form the scaffold.
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novel Forsterite polycaprolactone nanocomposite scaffold for tissue engineering applications
Materials Letters, 2011Co-Authors: Mani Diba, M H Fathi, Mahshid KharazihaAbstract:Abstract Novel highly porous nanocomposite scaffolds consisting of polycaprolactone (PCL) and Forsterite nanopowder were prepared by a solvent-casting/particle-leaching method. In addition, the effects of Forsterite nanopowder contents on the structure of the scaffolds were investigated to provide an appropriate composite for bone regenerative medicine. Results showed that the scaffolds exhibited high porosity (up to 92%) with open pores of 100–300 μm average diameters. This porosity increased with decreasing Forsterite nanopowder content. In addition, the pore walls contained numerous micropores. Microstructure studies showed that the pores were well distributed throughout the structures. Furthermore, the bioactive Forsterite nanoparticles were homogenously distributed within the PCL matrix of the scaffolds, which contained up to 30 wt.% Forsterite nanopowder. This porous structure with micropores provides the properties required for bone tissue engineering applications.
M H Fathi - One of the best experts on this subject based on the ideXlab platform.
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surface modification of stainless steel implants using nanostructured Forsterite mg2sio4 coating for biomaterial applications
Surface & Coatings Technology, 2015Co-Authors: Mitra Kheirkhah, M H Fathi, H R Salimijazi, Mehdi RazaviAbstract:Abstract The main aim of this research was the preparation of the Forsterite (Mg 2 SiO 4 ) coating on the surface of 316L stainless steel (316L SS) substrate. For this purpose, the nanostructured Forsterite was coated on the 316L SS substrate using the sol–gel dip coating technique. Structural characterization techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDX) were utilized to investigate the phase structure, morphology and elemental composition of the uncoated and coated samples. Corrosion properties of samples were studied using the electrochemical measurements in simulated body fluid (SBF). The in vitro bioactivity evaluation of the Forsterite coated samples was conducted by soaking the samples in the SBF at the temperature of 37 °C. The results showed that, a crack-free and homogeneous Forsterite coating with the crystallite size of around 40 nm was successfully achieved on the surface of 316L SS substrate. The corrosion current density of the Forsterite coated samples was lesser than that of the uncoated ones indicating the improvement of corrosion resistance of the metallic substrate using the Forsterite coating. Deposition of Ca and P-contained products on the surface of coated samples during the incubation in the SBF solution confirmed the bioactivity behavior of the Forsterite coated samples. Consequently, the 316L SS substrate coated with nanostructured Forsterite may be an appropriate selection for dental and orthopedic implant applications.
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effects of surface modification on the mechanical and structural properties of nanofibrous poly e caprolactone Forsterite scaffold for tissue engineering applications
Materials Science and Engineering: C, 2013Co-Authors: Mahshid Kharaziha, M H Fathi, Hossein EdrisAbstract:Composite scaffolds consisting of polymers reinforced with ceramic nanoparticles are widely applied for hard tissue engineering. However, due to the incompatible polarity of ceramic nanoparticles with polymers, they tend to agglomerate in the polymer matrix which results in undesirable effects on the integral properties of composites. In this research, Forsterite (Mg2SiO4) nanoparticles was surface esterified by dodecyl alcohol and nanofibrous poly(e-caprolactone)(PCL)/modified Forsterite scaffolds were developed through electrospinning technique. The aim of this research was to investigate the properties of surface modified Forsterite nanopowder and PCL/modified Forsterite scaffolds, before and after hydrolytic treatment, as well as the cellular attachment and proliferation. Results demonstrated that surface modification of nanoparticles significantly enhanced the tensile strength and toughness of scaffolds upon 1.5- and 4-folds compared to unmodified samples, respectively, due to improved compatibility between matrix and filler. Hydrolytic treatment of scaffolds also modified the bioactivity and cellular attachment and proliferation due to greatly enhanced hydrophilicity of the Forsterite nanoparticles after this process compared to surface modified samples. Results suggested that surface modification of Forsterite nanopowder and hydrolytic treatment of the developed scaffolds were effective approaches to address the issues in the formation of composite fibers and resulted in development of bioactive composite scaffolds with ideal mechanical and structural properties for bone tissue engineering applications.
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preparation and characterization of polycaprolactone Forsterite nanocomposite porous scaffolds designed for bone tissue regeneration
Composites Science and Technology, 2012Co-Authors: Mani Diba, Mahshid Kharaziha, M H Fathi, Mazaher Gholipourmalekabadi, Ali SamadikuchaksaraeiAbstract:Abstract Biocomposite scaffolds made from polymers and bioceramics can provide the mechanical structure necessary for osteoinductivity in the growth of new bone. The aim of this research was to investigate the properties of a novel nanocomposite scaffold made from a combination of polycaprolactone (PCL) and Forsterite nanopowder which could find use in bone tissue engineering applications. The scaffold itself was fabricated by a method of solvent casting and particle leaching. The effect of Forsterite content on the mechanical properties, bioactivity, biodegradability, and cytotoxicity of the scaffolds was investigated. Significant improvement in the mechanical properties was observed in the nanocomposite scaffolds as compared to that seen in the pure PCL scaffolds. Bioactivity was also observed in the nanocomposite scaffolds, a trait which was not present in the pure PCL scaffolds. Biodegradation assay indicated that the addition of Forsterite nanopowder could modulate the degradation rate of PCL. In vitro tests of cytotoxicity and osteoblast proliferation showed that the nanocomposite scaffolds were non-cytotoxic, thereby allowing cells to adhere, grow, and proliferate on the surface of these scaffolds. The results obtained in this experiment suggest that the combination of PCL with Forsterite nanopowder can be used to form scaffolds suitable for use in bone tissue engineering. The exact material behavior required can be adjusted through variation of the ratio between PCL and Forsterite nanopowder used to form the scaffold.
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novel Forsterite polycaprolactone nanocomposite scaffold for tissue engineering applications
Materials Letters, 2011Co-Authors: Mani Diba, M H Fathi, Mahshid KharazihaAbstract:Abstract Novel highly porous nanocomposite scaffolds consisting of polycaprolactone (PCL) and Forsterite nanopowder were prepared by a solvent-casting/particle-leaching method. In addition, the effects of Forsterite nanopowder contents on the structure of the scaffolds were investigated to provide an appropriate composite for bone regenerative medicine. Results showed that the scaffolds exhibited high porosity (up to 92%) with open pores of 100–300 μm average diameters. This porosity increased with decreasing Forsterite nanopowder content. In addition, the pore walls contained numerous micropores. Microstructure studies showed that the pores were well distributed throughout the structures. Furthermore, the bioactive Forsterite nanoparticles were homogenously distributed within the PCL matrix of the scaffolds, which contained up to 30 wt.% Forsterite nanopowder. This porous structure with micropores provides the properties required for bone tissue engineering applications.
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novel fabrication of Forsterite scaffold with improved mechanical properties
Journal of Alloys and Compounds, 2011Co-Authors: Hamed Ghomi, Mehran Jaberzadeh, M H FathiAbstract:Abstract In this study, the macroporous Forsterite scaffolds with highly interconnected spherical pores, with sizes ranged from 50 to 200 μm have been successfully fabricated via gelcasting method. The crystallite size of the Forsterite scaffolds was measured in the range 26–35 nm. Total porosity of different bodies sintered at different sintering temperatures was calculated in the range 81–86%, while open porosity ranges from 69 to 78%. The maximum values of compressive strength and elastic modulus of the prepared scaffolds were found to be about 2.43 MPa and 182 MPa, respectively, which are close to the lower limit of the compressive strength and elastic modulus of cancellous bone and the compressive strength is equal to the standard for a porous bioceramic bone implant (2.4 MPa). Transmission electron microscopy analyses showed that the particle sizes are smaller than 100 nm. In vitro test in the simulated body fluid proved the good bioactivity of the prepared scaffold. It seems that, the mentioned properties could make the Forsterite scaffold appropriate for tissue engineering applications, but cell culture and in vivo tests are needed for more confidence.
L B F M Waters - One of the best experts on this subject based on the ideXlab platform.
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the 69 μm Forsterite band in spectra of protoplanetary disks results from the herschel digit programme
Astronomy and Astrophysics, 2013Co-Authors: B Sturm, L B F M Waters, J Bouwman, Th Henning, Neal J Evans, E F Van Dishoeck, Joel D GreenAbstract:Context. We have analysed far-infrared spectra of 32 circumstellar disks around Herbig Ae/Be and T Tauri stars obtained within the Herschel key programme Dust, Ice and Gas in Time (DIGIT). The spectra were taken with the Photodetector Array Camera and Spectrometer (PACS) on board the Herschel Space Observatory. In this paper we focus on the detection and analysis of the 69 {$μ$}m emission band of the crystalline silicate Forsterite. Aims: This work aims at providing an overview of the 69 {$μ$}m Forsterite bands present in the DIGIT sample. We use characteristics of the emission band (peak position and FWHM) to derive the dust temperature and to constrain the iron content of the crystalline silicates. With this information, constraints can be placed on the spatial distribution of the Forsterite in the disk and the formation history of the crystalline grains. Methods: The 69 {$μ$}m Forsterite emission feature is analysed in terms of position and shape to derive the temperature and composition of the dust by comparison to laboratory spectra of that band. The PACS spectra are combined with existing Spitzer IRS spectra and we compare the presence and strength of the 69 {$μ$}m band to the Forsterite bands at shorter wavelengths. Results: A total of 32 disk sources have been observed. Out of these 32, 8 sources show a 69 {$μ$}m emission feature that can be attributed to Forsterite. With the exception of the T Tauri star AS 205, all of the detections are for disks associated with Herbig Ae/Be stars. Most of the Forsterite grains that give rise to the 69 {$μ$}m bands are found to be warm (~{}100-200 K) and iron-poor (less than ~{}2% iron). AB Aur is the only source where the emission cannot be fitted with iron-free Forsterite requiring approximately 3-4% of iron. Conclusions: Our findings support the hypothesis that the Forsterite grains form through an equilibrium condensation process at high temperatures. The large width of the emission band in some sources may indicate the presence of Forsterite reservoirs at different temperatures. The connection between the strength of the 69 and 33 {$μ$}m bands shows that at least part of the emission in these two bands originates fom the same dust grains. We further find that any model that can explain the PACS and the Spitzer IRS observations must take the effects of a wavelength dependent optical depth into account. We find weak indications of a correlation of the detection rate of the 69 {$μ$}m band with the spectral type of the host stars in our sample. However, the sample size is too small to obtain a definitive result. Appendix A is available in electronic form at http://www.aanda.org
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low abundance strong features window dressing crystalline Forsterite in the disk wall of hd 100546
Astronomy and Astrophysics, 2011Co-Authors: Gijs D Mulders, L B F M Waters, C Dominik, B Sturm, J Bouwman, M Min, A VerhoeffAbstract:Context. Forsterite is one of the crystalline dust species that is often observed in protoplanetary disks and solar system comets. Being absent in the interstellar medium, it must be produced during the disk lifetime. It can therefore serve as a tracer of dust processing and disk evolution, which can lead to a better understanding of the physical processes occurring in the disk, and possibly planet formation. However, the connection of these processes with the overall disk crystallinity remains unclear. Aims. We aim to characterize the Forsterite abundance and spatial distribution in the disk of the Herbig Be star HD 100546, to investigate if a connection exists with the large disk gap. Methods. We use a 2D radiative transfer code, MCMax, to model the circumstellar dust around HD 100546. We use VISIR Q-band imaging to probe the outer disk geometry and mid-infrared features to model the spatial distribution of Forsterite. The temperaturedependent shape of the 69 μm feature observed with Herschel ��� /PACS is used as a critical tool to constrain this distribution. Results. We find a crystalline mass fraction of 40–60%, located close to the disk wall between 13 and 20 AU, and possibly farther out at the disk surface. The Forsterite is in thermal contact with the other dust species. We put an upper limit on the iron content of Forsterite of 0.3%. Conclusions. Optical depth effects play a key role in explaining the observed Forsterite features, hiding warm Forsterite from view at short wavelengths. The disk wall acts as a showcase: it displays a localized high abundance of Forsterite, which gives rise to a high observed crystallinity, while the overall mass fraction of Forsterite is a factor of ten lower.
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low abundance strong features window dressing crystalline Forsterite in the disk wall of hd 100546
arXiv: Solar and Stellar Astrophysics, 2011Co-Authors: Gijs D Mulders, L B F M Waters, C Dominik, B Sturm, J Bouwman, M Min, A VerhoeffAbstract:Forsterite is one of the crystalline dust species that is often observed in protoplanetary disks and solar system comets. Being absent in the interstellar medium, it must be produced during the disk lifetime. It can therefore serve as a tracer of dust processing and disk evolution, which can lead to a better understanding of the physical processes occurring in the disk, and possibly planet formation. However, the connection of these processes with the overall disk crystallinity remains unclear. We aim to characterize the Forsterite abundance and spatial distribution in the disk of the Herbig Be star HD 100546, to investigate if a connection exists with the large disk gap. We use a 2D radiative transfer code, MCMax, to model the circumstellar dust around HD 100546. We use VISIR Q-band imaging to probe the outer disk geometry and mid-infrared features to model the spatial distribution of Forsterite. The temperature-dependent shape of the 69 micron feature observed with Herschel PACS is used as a critical tool to constrain this distribution. We find a crystalline mass fraction of 40 - 60 %, located close to the disk wall between 13 and 20 AU, and possibly farther out at the disk surface. The Forsterite is in thermal contact with the other dust species. We put an upper limit on the iron content of Forsterite of 0.3 %. Optical depth effects play a key role in explaining the observed Forsterite features, hiding warm Forsterite from view at short wavelengths. The disk wall acts as a showcase: it displays a localized high abundance of Forsterite, which gives rise to a high observed crystallinity, while the overall mass fraction of Forsterite is a factor of ten lower.
Gijs D Mulders - One of the best experts on this subject based on the ideXlab platform.
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low abundance strong features window dressing crystalline Forsterite in the disk wall of hd 100546
Astronomy and Astrophysics, 2011Co-Authors: Gijs D Mulders, L B F M Waters, C Dominik, B Sturm, J Bouwman, M Min, A VerhoeffAbstract:Context. Forsterite is one of the crystalline dust species that is often observed in protoplanetary disks and solar system comets. Being absent in the interstellar medium, it must be produced during the disk lifetime. It can therefore serve as a tracer of dust processing and disk evolution, which can lead to a better understanding of the physical processes occurring in the disk, and possibly planet formation. However, the connection of these processes with the overall disk crystallinity remains unclear. Aims. We aim to characterize the Forsterite abundance and spatial distribution in the disk of the Herbig Be star HD 100546, to investigate if a connection exists with the large disk gap. Methods. We use a 2D radiative transfer code, MCMax, to model the circumstellar dust around HD 100546. We use VISIR Q-band imaging to probe the outer disk geometry and mid-infrared features to model the spatial distribution of Forsterite. The temperaturedependent shape of the 69 μm feature observed with Herschel ��� /PACS is used as a critical tool to constrain this distribution. Results. We find a crystalline mass fraction of 40–60%, located close to the disk wall between 13 and 20 AU, and possibly farther out at the disk surface. The Forsterite is in thermal contact with the other dust species. We put an upper limit on the iron content of Forsterite of 0.3%. Conclusions. Optical depth effects play a key role in explaining the observed Forsterite features, hiding warm Forsterite from view at short wavelengths. The disk wall acts as a showcase: it displays a localized high abundance of Forsterite, which gives rise to a high observed crystallinity, while the overall mass fraction of Forsterite is a factor of ten lower.
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low abundance strong features window dressing crystalline Forsterite in the disk wall of hd 100546
arXiv: Solar and Stellar Astrophysics, 2011Co-Authors: Gijs D Mulders, L B F M Waters, C Dominik, B Sturm, J Bouwman, M Min, A VerhoeffAbstract:Forsterite is one of the crystalline dust species that is often observed in protoplanetary disks and solar system comets. Being absent in the interstellar medium, it must be produced during the disk lifetime. It can therefore serve as a tracer of dust processing and disk evolution, which can lead to a better understanding of the physical processes occurring in the disk, and possibly planet formation. However, the connection of these processes with the overall disk crystallinity remains unclear. We aim to characterize the Forsterite abundance and spatial distribution in the disk of the Herbig Be star HD 100546, to investigate if a connection exists with the large disk gap. We use a 2D radiative transfer code, MCMax, to model the circumstellar dust around HD 100546. We use VISIR Q-band imaging to probe the outer disk geometry and mid-infrared features to model the spatial distribution of Forsterite. The temperature-dependent shape of the 69 micron feature observed with Herschel PACS is used as a critical tool to constrain this distribution. We find a crystalline mass fraction of 40 - 60 %, located close to the disk wall between 13 and 20 AU, and possibly farther out at the disk surface. The Forsterite is in thermal contact with the other dust species. We put an upper limit on the iron content of Forsterite of 0.3 %. Optical depth effects play a key role in explaining the observed Forsterite features, hiding warm Forsterite from view at short wavelengths. The disk wall acts as a showcase: it displays a localized high abundance of Forsterite, which gives rise to a high observed crystallinity, while the overall mass fraction of Forsterite is a factor of ten lower.
A Verhoeff - One of the best experts on this subject based on the ideXlab platform.
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low abundance strong features window dressing crystalline Forsterite in the disk wall of hd 100546
Astronomy and Astrophysics, 2011Co-Authors: Gijs D Mulders, L B F M Waters, C Dominik, B Sturm, J Bouwman, M Min, A VerhoeffAbstract:Context. Forsterite is one of the crystalline dust species that is often observed in protoplanetary disks and solar system comets. Being absent in the interstellar medium, it must be produced during the disk lifetime. It can therefore serve as a tracer of dust processing and disk evolution, which can lead to a better understanding of the physical processes occurring in the disk, and possibly planet formation. However, the connection of these processes with the overall disk crystallinity remains unclear. Aims. We aim to characterize the Forsterite abundance and spatial distribution in the disk of the Herbig Be star HD 100546, to investigate if a connection exists with the large disk gap. Methods. We use a 2D radiative transfer code, MCMax, to model the circumstellar dust around HD 100546. We use VISIR Q-band imaging to probe the outer disk geometry and mid-infrared features to model the spatial distribution of Forsterite. The temperaturedependent shape of the 69 μm feature observed with Herschel ��� /PACS is used as a critical tool to constrain this distribution. Results. We find a crystalline mass fraction of 40–60%, located close to the disk wall between 13 and 20 AU, and possibly farther out at the disk surface. The Forsterite is in thermal contact with the other dust species. We put an upper limit on the iron content of Forsterite of 0.3%. Conclusions. Optical depth effects play a key role in explaining the observed Forsterite features, hiding warm Forsterite from view at short wavelengths. The disk wall acts as a showcase: it displays a localized high abundance of Forsterite, which gives rise to a high observed crystallinity, while the overall mass fraction of Forsterite is a factor of ten lower.
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low abundance strong features window dressing crystalline Forsterite in the disk wall of hd 100546
arXiv: Solar and Stellar Astrophysics, 2011Co-Authors: Gijs D Mulders, L B F M Waters, C Dominik, B Sturm, J Bouwman, M Min, A VerhoeffAbstract:Forsterite is one of the crystalline dust species that is often observed in protoplanetary disks and solar system comets. Being absent in the interstellar medium, it must be produced during the disk lifetime. It can therefore serve as a tracer of dust processing and disk evolution, which can lead to a better understanding of the physical processes occurring in the disk, and possibly planet formation. However, the connection of these processes with the overall disk crystallinity remains unclear. We aim to characterize the Forsterite abundance and spatial distribution in the disk of the Herbig Be star HD 100546, to investigate if a connection exists with the large disk gap. We use a 2D radiative transfer code, MCMax, to model the circumstellar dust around HD 100546. We use VISIR Q-band imaging to probe the outer disk geometry and mid-infrared features to model the spatial distribution of Forsterite. The temperature-dependent shape of the 69 micron feature observed with Herschel PACS is used as a critical tool to constrain this distribution. We find a crystalline mass fraction of 40 - 60 %, located close to the disk wall between 13 and 20 AU, and possibly farther out at the disk surface. The Forsterite is in thermal contact with the other dust species. We put an upper limit on the iron content of Forsterite of 0.3 %. Optical depth effects play a key role in explaining the observed Forsterite features, hiding warm Forsterite from view at short wavelengths. The disk wall acts as a showcase: it displays a localized high abundance of Forsterite, which gives rise to a high observed crystallinity, while the overall mass fraction of Forsterite is a factor of ten lower.