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Your search keyword '"J. Boxleitner"' showing total 3 results
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3 results on '"J. Boxleitner"'

1. Fiber Orientation Effects in Fused Filament Fabrication of Air-Cooled Heat Exchangers

Author

Tom Mulholland, Natalie Rudolph, J. Boxleitner, Sebastian Goris, and Tim A. Osswald

Subjects
chemistry.chemical_classification, Materials science, 020502 materials, General Engineering, Fused filament fabrication, 02 engineering and technology, Polymer, 021001 nanoscience & nanotechnology, Thermal conductivity, 0205 materials engineering, chemistry, Polyamide, Heat exchanger, General Materials Science, Extrusion, Fiber, Composite material, 0210 nano-technology, Anisotropy
Abstract

Fused filament fabrication (FFF) is a type of additive manufacturing based on material extrusion that has long been considered a prototyping technology. However, the right application of material, process, and product can be used for manufacturing of end-use products, such as air-cooled heat exchangers made by adding fillers to the base polymer, enhancing the thermal conductivity. Fiber fillers lead to anisotropic thermal conductivity, which is governed by the process-induced fiber orientation. This article presents an experimental study on the microstructure-property relationship for carbon fiber-filled polyamide used in FFF. The fiber orientation is measured by micro-computed tomography, and the thermal conductivity of manufactured samples is measured. Although the thermal conductivity is raised by more than three times in the fiber orientation direction at a load of only 12 vol.%, the enhancement is low in the other directions, and this anisotropy, along with certain manufacturing restrictions, influences the final part performance.

Published
2018
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3. Bacterial Cellulose Shifts Transcriptome and Proteome of Cultured Endothelial Cells Towards Native Differentiation.

Author

Feil G, Horres R, Schulte J, Mack AF, Petzoldt S, Arnold C, Meng C, Jost L, Boxleitner J, Kiessling-Wolf N, Serbest E, Helm D, Kuster B, Hartmann I, Korff T, and Hahne H

Subjects
Cell Separation, Cells, Cultured, Cluster Analysis, Collagen pharmacology, Gene Expression Profiling, Human Umbilical Vein Endothelial Cells drug effects, Humans, Proteomics, RNA, Messenger genetics, RNA, Messenger metabolism, Cell Differentiation drug effects, Cellulose pharmacology, Human Umbilical Vein Endothelial Cells cytology, Human Umbilical Vein Endothelial Cells metabolism, Proteome metabolism, Transcriptome genetics
Abstract

Preserving the native phenotype of primary cells in vitro is a complex challenge. Recently, hydrogel-based cellular matrices have evolved as alternatives to conventional cell culture techniques. We developed a bacterial cellulose-based aqueous gel-like biomaterial, dubbed Xellulin, which mimics a cellular microenvironment and seems to maintain the native phenotype of cultured and primary cells. When applied to human umbilical vein endothelial cells (HUVEC), it allowed the continuous cultivation of cell monolayers for more than one year without degradation or dedifferentiation. To investigate the impact of Xellulin on the endothelial cell phenotype in detail, we applied quantitative transcriptomics and proteomics and compared the molecular makeup of native HUVEC, HUVEC on collagen-coated Xellulin and collagen-coated cell culture plastic (polystyrene).Statistical analysis of 12,475 transcripts and 7831 proteins unveiled massive quantitative differences of the compared transcriptomes and proteomes. K -means clustering followed by network analysis showed that HUVEC on plastic upregulate transcripts and proteins controlling proliferation, cell cycle and protein biosynthesis. In contrast, HUVEC on Xellulin maintained, by and large, the expression levels of genes supporting their native biological functions and signaling networks such as integrin, receptor tyrosine kinase MAP/ERK and PI3K signaling pathways, while decreasing the expression of proliferation associated proteins. Moreover, CD34-an endothelial cell differentiation marker usually lost early during cell culture - was re-expressed within 2 weeks on Xellulin but not on plastic. And HUVEC on Xellulin showed a significantly stronger functional responsiveness to a prototypic pro-inflammatory stimulus than HUVEC on plastic.Taken together, this is one of the most comprehensive transcriptomic and proteomic studies of native and propagated HUVEC, which underscores the importance of the morphology of the cellular microenvironment to regulate cellular differentiation, and demonstrates, for the first time, the potential of Xellulin as versatile tool promoting an in vivo -like phenotype in primary and propagated cell culture., (© 2017 by The American Society for Biochemistry and Molecular Biology, Inc.)

Published
2017
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