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Wolters H.H.,Muenster University Hospital | Heistermann H.P.,General and Visceral Surgery | Stppeler S.,Muenster University Hospital | Hierlemann H.,Institute of Textile Technology and Process Engineering | And 2 more authors.
Journal of Urology | Year: 2010

Purpose: Ureteral defect lesions are severe complications caused by iatrogenic lesions or trauma. For ureteral defect lesions elaborate surgical intervention is needed, such as autotransplantation or ureteral replacement with small bowel. Thus, we developed a new technique for ureteral defect reconstruction in a pig model using an autologous vein graft splinted by an endoluminal biodegradable poly-L-lactic acid stent (Institute of Textile Technology and Process Engineering, Denkendorf, Germany). Materials and Methods: In 42 pigs we removed the external jugular vein and used it as an autologous vein graft. After median laparotomy a 3 cm segment was resected from the proximal ureter and replaced by the vein with or without an endoluminal biodegradable poly-L-lactic acid stent. As controls, we used 14 pigs. We observed survival, kidney function, and neoureteral and kidney morphological changes for 7 days and for 6 months. Results: After 6 months the stent material was completely broken down and the vein graft was relined with urothelium. It resembled native ureter with cytokeratin-7 positive columnar epithelium and newly formed capillaries in the ureteral wall. All animals had normal kidney function without renal pelvis congestion. Conclusions: This new technique for ureteral defect reconstruction using an autologous vein graft and a biodegradable endoluminal stent is feasible. It is an interesting alternative in the clinic due to the preservation of physiological urine passage and the antireflux mechanism. © 2010 American Urological Association Education and Research, Inc.

Dastjerdi R.,University of Yazd | Montazer M.,Amirkabir University of Technology | Stegmaier T.,Institute of Textile Technology and Process Engineering | Moghadam M.B.,Allame Tabatabaee University
Colloids and Surfaces B: Biointerfaces | Year: 2012

Recently developing bioinspired super-hydrophobic surfaces to achieve self-cleaning properties has been driving numerous researches. However, hydrophilicity is one of the most important features of garment comfort. Therefore, accomplishing self-cleaning and stain repellency on hydrophilic surfaces would be a high topic of interest. This research is concerned with wettability mechanism; static and dynamic study of contact angle through water droplet absorption on the multiple scale nano-roughness covered by different weight ratio of oppositely charged inorganic nanoparticles and amino-functionalized polysiloxane. The results revealed that the second layer of the resin formed on the surface can show an amphiphilic hybrid block copolymer-like feature whose dual action can be intensified during water droplet absorption by the created multiple size nano-roughness. This unique structure can create a stain repellent but hydrophilic surface with exceptional advantages. The mechanism has been deeply discussed according to the evidence on droplet edge interfacial energy changes as a driving force to overcome meta-stable Cassie state on the multiple size nano-roughness with amphiphilic feature. A lotus-like nano-roughness has been also observed on the SEM micrographs. Based on a statistically approached experimental design, the effect of variant factors on droplet absorption time, static, advancing, receding contact angles and self-cleaning properties has been mathematically modeled according to the response surface methodology (RSM). © 2011 Elsevier B.V.

Kuppers S.,Institute of Textile Technology and Process Engineering | Thumm J.,Canyon Bicycles GmbH | Muller L.,Institute of Textile Technology and Process Engineering | Ewert D.,Institute of Textile Technology and Process Engineering | Gresser G.T.,Institute of Textile Technology and Process Engineering
Materials Science Forum | Year: 2015

In many areas of fiber composite technology there is a great need for a solution of how to manufacture nodal elements and/or ramifications with an optimized force flow process and by machine, i.e. economically. Examples are hubs of wind power plants, branch points in framework constructions in the building industry and air and space travel, the automotive industry, ramified vein prostheses in medical technology, or the connecting nodes of bicycle frames. Motivated by this, the potential of plant ramifications as a model for new compound fiber constructions was investigated. Ramified species with pronounced fiber matrix structure served, inter alia, as biological models. The PBG Freiburg examined tree-formed monocotyledons of the genera Dracaena and Freycinetia[1], the BTU Dresden column cacti of the genera Pilsocereus and Myrtillocactus [2]. The plants exhibit Y-shaped and T-shaped ramifications, whose angles resemble those of the ramified technical construction units that are to be optimised bionically. As the investigations confirm, the ramifications, which are nearly completely unexplored, are characterised by very interesting mechanical characteristics, like e.g. good-natured breaking behavior and good oscillation damping caused by high energy absorption, as well as a high lightweight construction potential. The results demonstrate the high potential for a successful technical transfer of the results of the proposed project. In this paper, three different types of braided branches are represented. Firstly, the aforementioned nature-inspired Y-junctions are shown. Secondly, a type of branch with a special braiding technique that allows branches with asymmetric design of the arms and a braiding technique for the automated production of loop connections is presented. © (2015) Trans Tech Publications, Switzerland.

Dastjerdi R.,University of Yazd | Montazer M.,Amirkabir University of Technology | Shahsavan S.,Tehran University of Medical Sciences | Bottcher H.,GMBU e.V. | And 2 more authors.
Colloids and Surfaces B: Biointerfaces | Year: 2013

This research has designed innovative Ag/TiO2 polysiloxane-shield nano-reactors on the PET fabric to develop novel durable bio-photocatalyst purifiers. To create these very fine nano-reactors, oppositely surface charged multiple size nanoparticles have been applied accompanied with a crosslinkable amino-functionalized polysiloxane (XPs) emulsion. Investigation of photocatalytic dye decolorization efficiency revealed a non-heterogeneous mechanism including an accelerated degradation of entrapped dye molecules into the structural polysiloxane-shield nano-reactors. In fact, dye molecules can be adsorbed by both Ag and XPs due to their electrostatic interactions and/or even via forming a complex with them especially with silver NPs. The absorbed dye and active oxygen species generated by TiO2 were entrapped by polysiloxane shelter and the presence of silver nanoparticles further attract the negative oxygen species closer to the adsorbed dye molecules. In this way, the dye molecules are in close contact with concentrated active oxygen species into the created nano-reactors. This provides an accelerated degradation of dye molecules. This non-heterogeneous mechanism has been detected on the sample containing all of the three components. Increasing the concentration of Ag and XPs accelerated the second step beginning with an enhanced rate. Further, the treated samples also showed an excellent antibacterial activity. © 2012 Elsevier B.V.

Buchmeiser M.R.,University of Stuttgart | Buchmeiser M.R.,Institute of Textile Chemistry and Chemical Fibers | Kammerer J.A.,University of Stuttgart | Naumann S.,University of Stuttgart | And 5 more authors.
Macromolecular Materials and Engineering | Year: 2015

Epoxy-based fiber-matrix composites based on a single-component curing system with pot times >>two weeks are described. Bisphenol-A-diglycidyl ether and hexahydrophthalic anhydride were used as epoxy matrix precursors; 1,3-dicyclohexyl-3,4,5,6-tetrahydropyrimidinium carboxylate (6Cy-CO2) was used as latent pre-catalyst. Glass fiber-reinforced epoxy resins were obtained both via thermal curing under air and under vacuum-assisted resin infusion conditions. The high quality of the resulting composites and the absence of any air inclusion were confirmed by DSC and x-ray tomography. Rheological and kinetic data revealed that the 6Cy-CO2-based systems allow for an advanced processing and outrival commercial amine-based hardeners in terms of speed of curing. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Brochhausen C.,Johannes Gutenberg University Mainz | Schmitt V.H.,Johannes Gutenberg University Mainz | Rajab T.K.,Harvard University | Planck C.N.E.,University of Tübingen | And 4 more authors.
Journal of Biomedical Materials Research - Part A | Year: 2011

Peritoneal adhesions remain a relevant clinical problem despite the currently available prophylactic barrier materials. So far, the physical separation of traumatized serosa areas using barriers represents the most important clinical strategy for adhesion prevention. However, the optimal material has not yet been found. Further optimization or pharmacological functionalization of these barriers could give an innovative input for peritoneal adhesion prevention. Therefore, a more complete understanding of pathogenesis is required. On the basis of the pathophysiology of adhesion formation the main barriers currently in clinical practice as well as new innovations are discussed in the present review. Physiologically, mesothelial cells play a decisive role in providing a frictionless gliding surface on the serosa. Adhesion formation results from a cascade of events and is regulated by a variety of cellular and humoral factors. The main clinically applied strategy for adhesion prevention is based on the use of liquid or solid adhesion barriers to separate physically any denuded tissue. Both animal and human trials have not yet been able to identify the optimal barrier to prevent adhesion formation in a sustainable way. Therefore, further developments are required for effective prevention of postoperative adhesion formation. To reach this goal the combination of structural modification and pharmacological functionalization of barrier materials should be addressed. Achieving this aim requires the interaction between basic research, materials science and clinical expertise. © 2011 Wiley Periodicals, Inc.

Brochhausen C.,Johannes Gutenberg University Mainz | Schmitt V.H.,Johannes Gutenberg University Mainz | Planck C.N.E.,University of Tübingen | Rajab T.K.,Harvard University | And 8 more authors.
Journal of Gastrointestinal Surgery | Year: 2012

Introduction: The formation of peritoneal adhesions still is a relevant clinical problem after abdominal surgery. Until today, the most important clinical strategies for adhesion prevention are accurate surgical technique and the physical separation of traumatized serosal areas. Despite a variety of barriers which are available in clinical use, the optimal material has not yet been found. Discussion: Mesothelial cells play a crucial physiological role in frictionless gliding of the serosa and the maintenance of an antiadhesive surface. The formation of postoperative adhesions results from a cascade of events and is regulated by various cellular and humoral factors. Therefore, optimization or functionalization of barrier materials by developments interacting with this cascade on a structural or pharmacological level could give an innovative input for future strategies in peritoneal adhesion prevention. For this purpose, the proper understanding of the formal pathogenesis of adhesion formation is essential. Based on the physiology of the serosa and the pathophysiology of adhesion formation, the available barriers in current clinical practice as well as new innovations are discussed in the present review. © 2012 The Society for Surgery of the Alimentary Tract.

Witt M.-U.,Institute of Textile Technology and Process Engineering | Milwich M.,Institute of Textile Technology and Process Engineering | Gresser G.T.,Institute of Textile Technology and Process Engineering | Hammer M.,Institute of Building Structures and Structural Design | Knippers J.,Institute of Building Structures and Structural Design
Materials Science Forum | Year: 2015

Fiber reinforced plastics, due to their good mechanical properties and simultaneously low density, are very attractive for many uses. They are also gaining more importance in the civil engineering applications. Bio composites based on sustainable raw materials are becoming much more attractive, especially in construction industry, due to their recyclability and eco balance benefits. In this paper, a method to develop a façade profile from regenerated viscose filament and bio resin system (PTP®) using pultrusion process is discussed. The PTP® resin system from Bio- Composites And More GmbH comprises of 60% epoxidized vegetable oil. The pultrusion process is optimized to reach 60 cm/min speed from the initial speed of 4 cm/min by modifying the resin mixture. Though the production speeds are below the industrial standards, economic production scale could be still reached. © (2015) Trans Tech Publications, Switzerland.

Haller N.,Ludwig Maximilians University of Munich | Hollweck T.,Ludwig Maximilians University of Munich | Thierfelder N.,Ludwig Maximilians University of Munich | Schulte J.,Ludwig Maximilians University of Munich | And 3 more authors.
ASAIO Journal | Year: 2013

Microcomputed tomography (μ-CT) is a nondestructive, high-resolution, three-dimensional method of analyzing objects. The aim of this study was to evaluate the feasibility of using μ-CT as a noninvasive method of evaluation for tissue-engineering applications. The polyurethane aortic heart valve scaffold was produced using a spraying technique. Cryopreserved/thawed homograft and biological heart valve were decellularized using a detergent mixture. Human endothelial cells and fibroblasts were derived from saphenous vein segments and were verified by immunocytochemistry. Heart valves were initially seeded with fibroblasts followed by colonization with endothelial cells. Scaffolds were scanned by a μ-CT scanner before and after decellularization as well as after cell seeding. Successful colonization was additionally determined by scanning electron microscopy (SEM) and immunohistochemistry (IHC). Microcomputed tomography accurately visualized the complex geometry of heart valves. Moreover, an increase in the total volume and wall thickness as well as a decrease in total surface was demonstrated after seeding. A confluent cell distribution on the heart valves after seeding was confirmed by SEM and IHC. We conclude that μ-CT is a new promising noninvasive method for qualitative and quantitative analysis of tissue-engineering processes. Copyright © 2013 by the American Society for Artificial Internal Organs.

Lehmann B.,Institute of Textile Technology and Process Engineering | Selvarayan S.K.,Institute of Textile Technology and Process Engineering | Ghomeshi R.,Institute of Textile Technology and Process Engineering | Gresser G.T.,Institute of Textile Technology and Process Engineering
Materials Science Forum | Year: 2015

Carbon fiber reinforced plastic (CFRP) was integrated with steel fibers in order to improve the toughness and to enhance the structural integrity during crash. An epoxy system with internal mold release was chosen as the matrix system. The steel fibers were either sandblasted or twisted to improve the fiber-matrix adhesion through a mechanical interlocking mechanism. The pull-out strength of surface modified steel fibers was doubled compared to the unmodified steel fibers. The steel fiber integration increased the maximum bending stress of the composites up to 20% whereas the strain to rupture reduced to 2.3%. The energy dissipation factor of the steel fiber integrated CFRPs was also reduced compared to CFRPs without steel fiber. An increase in fracture toughness for the CFRPs with steel fibers amounted to 17J. © (2015) Trans Tech Publications, Switzerland.

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