Hoang The - Academia.edu (original) (raw)
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Papers by Hoang The
PLoS ONE, 2013
The reconstruction of an auricle for congenital deformity or following trauma remains one of the ... more The reconstruction of an auricle for congenital deformity or following trauma remains one of the greatest challenges in reconstructive surgery. Tissue-engineered (TE) three-dimensional (3D) cartilage constructs have proven to be a promising option, but problems remain with regard to cell vitality in large cell constructs. The supply of nutrients and oxygen is limited because cultured cartilage is not vascular integrated due to missing perichondrium. The consequence is necrosis and thus a loss of form stability. The micro-surgical implantation of an arteriovenous loop represents a reliable technology for neovascularization, and thus vascular integration, of three-dimensional (3D) cultivated cell constructs. Auricular cartilage biopsies were obtained from 15 rabbits and seeded in 3D scaffolds made from polycaprolactone-based polyurethane in the shape and size of a human auricle. These cartilage cell constructs were implanted subcutaneously into a skin flap (1568 cm) and neovascularized by means of vascular loops implanted micro-surgically. They were then totally enhanced as 3D tissue and freely re-implanted in-situ through microsurgery. Neovascularization in the prefabricated flap and cultured cartilage construct was analyzed by microangiography. After explantation, the specimens were examined by histological and immunohistochemical methods. Cultivated 3D cartilage cell constructs with implanted vascular pedicle promoted the formation of engineered cartilaginous tissue within the scaffold in vivo. The auricles contained cartilage-specific extracellular matrix (ECM) components, such as GAGs and collagen even in the center oft the constructs. In contrast, in cultivated 3D cartilage cell constructs without vascular pedicle, ECM distribution was only detectable on the surface compared to constructs with vascular pedicle. We demonstrated, that the 3D flaps could be freely transplanted. On a microangiographic level it was evident that all the skin flaps and the implanted cultivated constructs were well neovascularized. The presented method is suggested as a promising alternative towards clinical application of engineered cartilaginous tissue for plastic and reconstructive surgery.
Multiple damage identification in beams using curvature mode shape has become a research focus of... more Multiple damage identification in beams using curvature mode shape has become a
research focus of increasing interest during the last few years. On this topic, most existing
studies address the sensitivity of curvature mode shape to multiple damage. A noticeable
deficiency of curvature mode shape, however, is its susceptibility to measurement
noise, easily impairing its advantage of sensitivity to multiple damage. To overcome this
drawback, the synergy between a wavelet transform (WT) and a Teager energy operator
(TEO) is explored, with the aim of ameliorating the curvature mode shape. The improved
curvature mode shape, termed the TEO-WT curvature mode shape, has inherent capabilities of immunity to noise and sensitivity to multiple damage. The efficacy of the
TEO-WT curvature mode shape is analytically verified by identifying multiple cracks
in cantilever beams, with particular emphasis on its ability to locate multiple damage in
noisy conditions; the applicability of the proposed curvature mode shape is experimentally validated by detecting multiple fairly thin slots in steel beams with mode shapes
acquired by a scanning laser vibrometer. The proposed curvature mode shape appears
sensitive to multiple damage and robust against noise, and therefore is well suited to
identification of multiple damage in beams in noisy environments.
This paper presents the comparison of several damage indicators to detect a damage in a railway b... more This paper presents the comparison of several damage indicators to detect a damage in a railway bridge. Two damage scenarios and one environmental effect are introduced to the structure. In this study, modal-based damage indicators are directly computed from the results of a numerical modal analysis while the wavelet-based indicators are based on the dynamic bridge response of train passage excitation. The artificially generated experimental data are extracted from numerical simulations of a train passage on the bridge using the finite element method with a Newmark time integration. The finite element model represents the EÜ Erfttalstraße, a bridge with 26.15m span width near Kerpen (Germany), which was extensively investigated in previous experimental campaigns. Based on experimentally obtained modal parameters the finite element model has been calibrated.
PLoS ONE, 2013
The reconstruction of an auricle for congenital deformity or following trauma remains one of the ... more The reconstruction of an auricle for congenital deformity or following trauma remains one of the greatest challenges in reconstructive surgery. Tissue-engineered (TE) three-dimensional (3D) cartilage constructs have proven to be a promising option, but problems remain with regard to cell vitality in large cell constructs. The supply of nutrients and oxygen is limited because cultured cartilage is not vascular integrated due to missing perichondrium. The consequence is necrosis and thus a loss of form stability. The micro-surgical implantation of an arteriovenous loop represents a reliable technology for neovascularization, and thus vascular integration, of three-dimensional (3D) cultivated cell constructs. Auricular cartilage biopsies were obtained from 15 rabbits and seeded in 3D scaffolds made from polycaprolactone-based polyurethane in the shape and size of a human auricle. These cartilage cell constructs were implanted subcutaneously into a skin flap (1568 cm) and neovascularized by means of vascular loops implanted micro-surgically. They were then totally enhanced as 3D tissue and freely re-implanted in-situ through microsurgery. Neovascularization in the prefabricated flap and cultured cartilage construct was analyzed by microangiography. After explantation, the specimens were examined by histological and immunohistochemical methods. Cultivated 3D cartilage cell constructs with implanted vascular pedicle promoted the formation of engineered cartilaginous tissue within the scaffold in vivo. The auricles contained cartilage-specific extracellular matrix (ECM) components, such as GAGs and collagen even in the center oft the constructs. In contrast, in cultivated 3D cartilage cell constructs without vascular pedicle, ECM distribution was only detectable on the surface compared to constructs with vascular pedicle. We demonstrated, that the 3D flaps could be freely transplanted. On a microangiographic level it was evident that all the skin flaps and the implanted cultivated constructs were well neovascularized. The presented method is suggested as a promising alternative towards clinical application of engineered cartilaginous tissue for plastic and reconstructive surgery.
Multiple damage identification in beams using curvature mode shape has become a research focus of... more Multiple damage identification in beams using curvature mode shape has become a
research focus of increasing interest during the last few years. On this topic, most existing
studies address the sensitivity of curvature mode shape to multiple damage. A noticeable
deficiency of curvature mode shape, however, is its susceptibility to measurement
noise, easily impairing its advantage of sensitivity to multiple damage. To overcome this
drawback, the synergy between a wavelet transform (WT) and a Teager energy operator
(TEO) is explored, with the aim of ameliorating the curvature mode shape. The improved
curvature mode shape, termed the TEO-WT curvature mode shape, has inherent capabilities of immunity to noise and sensitivity to multiple damage. The efficacy of the
TEO-WT curvature mode shape is analytically verified by identifying multiple cracks
in cantilever beams, with particular emphasis on its ability to locate multiple damage in
noisy conditions; the applicability of the proposed curvature mode shape is experimentally validated by detecting multiple fairly thin slots in steel beams with mode shapes
acquired by a scanning laser vibrometer. The proposed curvature mode shape appears
sensitive to multiple damage and robust against noise, and therefore is well suited to
identification of multiple damage in beams in noisy environments.
This paper presents the comparison of several damage indicators to detect a damage in a railway b... more This paper presents the comparison of several damage indicators to detect a damage in a railway bridge. Two damage scenarios and one environmental effect are introduced to the structure. In this study, modal-based damage indicators are directly computed from the results of a numerical modal analysis while the wavelet-based indicators are based on the dynamic bridge response of train passage excitation. The artificially generated experimental data are extracted from numerical simulations of a train passage on the bridge using the finite element method with a Newmark time integration. The finite element model represents the EÜ Erfttalstraße, a bridge with 26.15m span width near Kerpen (Germany), which was extensively investigated in previous experimental campaigns. Based on experimentally obtained modal parameters the finite element model has been calibrated.