Low-level exposure of MRSA to octenidine dihydrochloride does not select for resistance

No abstract available

Ageing of acrylate-based resins for stereolithography: thermal and humidity ageing behaviour studies

Purpose - The purpose of this paper is to describe the ageing behaviour of acrylate-based resins for stereolithography (SL) technology using different test methods and to investigate these effects on polymers. Design/methodology/approach - Controlling the polymer degradation requires an understanding of many different phenomena, including the different chemical mechanisms underlying structural changes in polymer macromolecules, the influences of polymer morphology, the complexities of oxidation chemistry and the complex reaction pathways of polymer additives. Several ageing characterization experiments are given. Findings - The paper covers the ageing process analysis of acrylate-based polymers. An overview of the ageing behaviour is given, along with the bandwidth of material characteristics for a prolonged lifetime of this material class. Research limitations/implications - For research and development in the field of rapid prototyping (RP) materials data about ageing behaviour and environmental effects are crucial. The authors show possible methods for measuring these effects and discuss the consequences in material research using a recently developed biocompatible SL resin as an example. Practical implications - The study of the ageing behaviour of polymers is important for understanding their usability, storage, lifetime and recycling. The presented polymeric formulations are able to meet the growing demand for both soft and stiff manufacturing resin materials in the engineering and medical fields. Originality/value - The analysis of the ageing behaviour of polymer materials is an important issue for engineering applications, recycling of post-consumer plastic waste, as well as the use of polymers as biological implants and matrices for drug delivery and the lifetime of an article. The paper gives an overview of details involving ageing behaviour and their meaning for applications of acrylate-based SL resins and is therefore of high importance to people with interest in long-term behaviour and ageing of RP material

Towards palm-size autonomous helicopters

muFly EU project started in 2006 with the idea to build an autonomous micro helicopter, comparable in size and weight to a small bird. Several scientific and technological objectives were identified. This spanned from system-level integration, high efficiency micro-actuation, highly integrated micro vision sensors and IMUs and also low processing power navigation algorithms. This paper shows how most of these objectives were reached, describing the approach and the role of each partner during the whole project. The paper describes also the technological developments achieved like the 80 g, 17 cm micro robotic-helicopter, the 8 g omnidirectional and steady-state laser scanner, the uIMU, the highly efficient micro motors, the high power-density fuel-cell and the successful graph-based navigation algorithms

Mechanical properties and bioanalytical characterization for a novel non-toxic flexible photopolymer formulation class

We present herein a new class of resin formulations for stereolithography, named FlexSL, with a broad bandwidth of tunable mechanical properties. The novel polyether(meth)acrylate based material class has outstanding material characteristics in combination with the advantages of being a biocompatible (meth)acrylate based processing material. FlexSL shows very promising results in several initial biocompatibility tests. This emphasizes its non-toxic behavior in a biomedical environment, caused mainly by the (meth)acrylate based core components. A short overview of mechanical and processing properties will be given in the end. The herein presented novel FlexSL materials show a significant lower cytotoxicity in contrast to commercial applied acrylic stereolithography resins. Further biocompatibility tests according to ISO 10993 protocols are planned. On the one hand, there are technical applications for this material (e.g. flaps, tubes, hoses, cables, sealing parts, connectors and other technical rubber-like applications), and on the other hand, broad fields of potential biomedical applications in which the FlexSL materials can be beneficial are obvious. Especially these could be small series production of medical products with special flexible material requirements. In addition, the usage for individual soft hearing aid shells, intra-operative planning services and tools like intra-op cutting templates and sawing guides is very attractive. The possibility to modify the FlexSL resins also for high-resolution applications makes it possible to manufacture now very flexible micro-prototypes with outstanding material characteristics and very fine structures with a minimum resolution of 20 mym and a layer thickness of minimal 5 myrn. These resin formulations are applicable and adjustable to other stereolithographic equipment available on the market

Oxidative Tryptophan Metabolism in Renal Allograft Recipients: Increased Kynurenine Synthesis is Associated with Inflammation and OKT3 Therapy.

Serum concentrations of tryptophan (TRP) and kynurenine (KYN) were determined in renal allograft recipients (RAR) as an index of interferon-gamma-induced, indoleamine-dioxygenase-catalysed TRP degradation. Serum TRP and KYN in RAR during periods of stable graft function were typically within the normal range, however, the median values for serum KYN demonstrated significant increases 5-7 days prior to biopsy-confirmed acute rejection (1.6-fold, P less than 0.01) and on the day of biopsy (1.7-fold, P less than 0.001). Serum KYN was also markedly elevated in patients who contracted viral or Gram-negative bacterial infections in the absence of graft rejection. Serum KYN was not correlated with serum creatinine in RAR nor were serum TRP or KYN affected by antirejection therapy with high dose steroids. Retrospective analysis of intra-patient changes in serum KYN demonstrated that KYN monitoring was a useful adjunct to serum creatinine in the early detection of first acute rejection episodes. The first course of OKT3 therapy was associated with low serum TRP and significant increases in serum KYN (two- to three-fold) following the first three doses. The time course of these abnormalities corresponded to that over which many of the side effects of the OKT3 \u27first dose reaction\u27 have been reported to occur. Significant changes in serum KYN were not observed in patients receiving repeat courses of OKT3 therapy. Significant decreases in serum TRP and significant increases in serum KYN were both prevalent and frequent in RAR during the first two postoperative months.(ABSTRACT TRUNCATED AT 250 WORDS