Several 2-nitroalkyl polysaccharide ethers (from pullulan (1), guar (2), agarose (3), inulin (4), cellulose (5), Na-α-polyglucuronate (6) and hydroxyethyl cellulose (7)) were synthesized by reaction with 2-nitro-1-alkenes (2-nitro-1-propene and 2-nitro-1-butene) formed in situ from 2-nitroalkyl acetates. Moderate to high efficiencies are obtained in concentrated aqueous solution/suspension for addition to 1-4 and 7. Analysis of this new class of polysaccharide derivatives with the aid of labeled 2-nitropropyl-2-13C pullulan revealed that the nitrogroup is a mixture of the nitroalkane and nitronic acid tautomers. Grafting of nitroalkenes is observed and, to a lesser extent, additional reactions of the nitro group (formation of carbonyl, oxime and allyl groups) take place. Reduction of 2-nitroalkyl polysaccharide ethers with Na2S2O4or Na2S2O4/NaBH4leads to complex polysaccharide ethers. The products obtained are most likely mixtures of starting material, nitroso compounds, hydroxylamines, hydroxypropyl ethers and sulfamates.
LINK
Polymeren, waaronder plastics, kennen we allemaal uit ons dagelijks leven. Van de plastic draagtas tot computeronderdelen en kopjes. Allemaal worden deze polymeren vervaardigd uit aardolie en afgeleide producten. De producten zijn zeer nuttig en breed toepasbaar, mede door de gunstige eigenschappen zoals warmteweerbaarheid, stevigheid en waterdichtheid. Daarentegen kennen polymeren ook een keerzijde, zoals het niet of moeilijk afbreekbaar zijn in de natuurlijke omgeving en de nadelen van het gebruik van fossiele bronnen: hun eindigheid en de ongecontroleerde emissie van broeikasgassen die verband houdt met klimaatverandering. Dit is een zichtbaar probleem bij onder meer De Plasticsoep, waar geen of beperkte afbraak plaatsvindt van plastics in de oceaan. De zoektocht naar alternatieven is daarom volop aan de gang.
DOCUMENT
OBJECTIVES: To evaluate the clinical performance of partial glass-ceramic (IPS e.max Press) posterior restorations.MATERIALS AND METHODS: A total of 765 restorations in 158 patients were placed between 2008 and 2018 and evaluated in a prospective study during regular dental care visits between 2015 and 2018. The restorations were luted with a conventional photo-polymerized resin composite (HFO) in conjunction with an Immediate Dentin Sealing procedure (IDS). Intra-oral photographs and radiographs were made and evaluated using USPHS criteria.RESULTS: The mean observation time was 53.3 months (range 3-113 months). Three absolute failures occurred (tooth fractures, n = 2; apical re-infection, n = 1) all leading to the loss of the restored tooth. Repairable and salvageable failures occurred in 9 teeth (endodontic complications, n = 7; secondary caries, n = 1; debonding, n = 1). The survival and success rates according to Kaplan-Meier after 5 years cumulated to 99.6% and 98.6%, respectively. Location (premolar/molar and mandibula/maxilla), pre-restorative endodontic status (vital/devitalised) and extension of the indirect ceramic restoration (number of sides and cusps involved) did not significantly affect the cumulative success rate (log rank test, p > 0.05). The condition of the vast majority of the restorations remained unaffected for 5 years.CONCLUSIONS: Partial glass-ceramic posterior restorations (pressed lithium disilicate (IPS e.max press, Ivoclar Vivadent) luted by means of a conventional photo-polymerized resin composite in conjunction with the use of an IDS procedure have an excellent medium-term prognosis.CLINICAL RELEVANCE: Partial glass-ceramic posterior restorations can be considered as a highly reliable treatment option. Location and extension of the restoration and pre-restorative endodontic status do not affect success rate.
DOCUMENT
Currently the advances in the field of 3D printing are causing a revolution in the (bio-)medical field. With applications ranging from patient-specific anatomical models for surgical preparation to prosthetic limbs and even scaffolds for tissue engineering, the possibilities seem endless. Today, the most widely used method is FDM printing. However, there is still a limited range of biodegradable and biocompatible materials available. Moreover, printed implants like for instance cardiovascular stents require higher resolution than is possible to reach with FDM. High resolution is crucial to avoid e.g. bacterial growth and aid to mechanical strength of the implant. For this reason, it would be interesting to consider stereolithography as alternative to FDM for applications in the (bio-) medical field. Stereolithography uses photopolymerizable resins to make high resolution prints. Because the amount of commercially available resins is limited and hardly biocompatible, here we investigate the possibility of using acrylates and vinylesters in an effort to expand the existing arsenal of biocompatible resins. Mechanical properties are tailorable by varying the crosslink density and by varying the spacer length. To facilitate rapid production of high-resolution prints we use masked SLA (mSLA) as an alternative to conventional SLA. mSLA cures an entire layer at a time and therefore uses less time to complete a print than conventional SLA. Additionally, with mSLA it takes the same time to make 10 prints as it would to make only one. Several formulations were prepared and tested for printability and mechanical strength.
MULTIFILE
Within this research a smart textile based light sensor was developed and integrated into a technical demonstrator of a remote identification system. This sensor is based on polymeric optical fibers (POFs) which contain fluorescent dopants and allows a remote detection using an optical laser pulse for identification. A possible use case for this system is remote identification to avoid “friendly fire” incidents.The smart textile sensor can be integrated with a very low footprint in protective textiles or other equipment of the individual. Besides defense applications, the system could also be adopted for applications in which a safe, secure and fast remote identification is needed.
MULTIFILE
Sensor platforms can benefit from the incorporation of polymerbrushes since brushes can concentrate the analyte near the sensor surface. Brushesthat absorb acetone vapor are of particular interest since acetone is an importantmarker for biological processes. We present a simple procedure to synthesize acetoneresponsivepoly(methyl acrylate) brushes. Using spectroscopic ellipsometry, we showthat these brushes respond within seconds and swell by more than 30% when exposedto acetone vapor. Moreover, quartz crystal microbalance measurements demonstrate that the brushes can be exploited to increasethe acetone detection sensitivity of sensors by more than a factor 6. Surprisingly, we find that the swelling ratio of the brushes inacetone vapor is independent of the grafting density and the degree of polymerization of the polymers in the brush. This isqualitatively different from swelling of the same brushes in liquid environments, where the swelling ratio decreases for increasinggrafting densities. Yet, it indicates that the brushes are robust and reproducible candidates for implementation in vapor sensorsystems.
MULTIFILE
This chapter will introduce the circular economy (CE) and Cradle to Cradle (C2C) models of sustainable production. It will reflect on the key blockages to a meaningful sustainable production and how these could be overcome, particularly in the context of business education. The case study of the course for bachelor’s students within International Business Management Studies (IBMS), and at University College in The Netherlands will be discussed. These case studies will illustrate the opportunities as well as potential pitfalls of the closed loop production models. The results of case studies’ analysis show that there was a mismatch between expectations of the sponsor companies and those of students on the one hand and a mismatch between theory and practice on the other hand. Helpful directions for future research and teaching practice are outlined. https://www.springer.com/gp/book/9783319713113#aboutBook https://www.linkedin.com/in/helenkopnina/
MULTIFILE
In this article we investigate the change in wetting behavior of inkjet printed materials on either hydrophilic or hydrophobic plasma treated patterns, to determine the minimum obtainable track width using selective patterned μPlasma printing. For Hexamethyl-Disiloxane (HMDSO)/N2 plasma, a decrease in surface energy of approx. 44 mN/m was measured. This resulted in a change in contact angle for water from <10 up to 105 degrees, and from 32 up to 46 degrees for Diethyleneglycol-Dimethaclylate (DEGDMA). For both the nitrogen, air and HMDSO/N2 plasma single pixel wide track widths of approx. 320 μm were measured at a plasma print height of 50 μm. Combining hydrophilic pretreatment of the glass substrate, by UV/Ozone or air μPlasma printing, with hydrophobic HMDSO/N2 plasma, the smallest hydrophilic area found was in the order of 300 μm as well.
DOCUMENT
From teh UU repository: "Background: Oral immunotherapy (OIT) is a promising therapeutic approach to treat food allergic patients. However, there are some concerns regarding its safety and long-term efficacy. The use of non-digestible oligosaccharides might improve OIT efficacy since they are known to directly modulate intestinal epithelial and immune cells in addition to acting as prebiotics. Aim: To investigate whether a diet supplemented with plant-derived fructo-oligosaccharides (FOS) supports the efficacy of OIT in a murine cow's milk allergy model and to elucidate the potential mechanisms involved. Methods: After oral sensitization to the cow's milk protein whey, female C3H/HeOuJ mice were fed either a control diet or a diet supplemented with FOS (1% w/w) and received OIT (10 mg whey) 5 days a week for 3 weeks by gavage. Intradermal (i.d.) and intragastric (i.g.) challenges were performed to measure acute allergic symptoms and mast cell degranulation. Blood and organs were collected to measure antibody levels and T cell and dendritic cell populations. Spleen-derived T cell fractions (whole spleen-and CD25-depleted) were transferred to naive recipient mice to confirm the involvement of regulatory T cells (Tregs) in allergy protection induced by OIT + FOS. Results: OIT + FOS decreased acute allergic symptoms and mast cell degranulation upon challenge and prevented the challenge-induced increase in whey-specific IgE as observed in sensitized mice. Early induction of Tregs in the mesenteric lymph nodes (MLN) of OIT + FOS mice coincided with reduced T cell responsiveness in splenocyte cultures. CD25 depletion in OIT + FOS-derived splenocyte suspensions prior to transfer abolished protection against signs of anaphylaxis in recipients. OIT + FOS increased serum galectin-9 levels. No differences in short-chain fatty acid (SCFA) levels in the cecum were observed between the treatment groups. Concisely, FOS supplementation significantly improved OIT in the acute allergic skin response, %Foxp3+ Tregs and %LAP+ Th3 cells in MLN, and serum galectin-9 levels. Conclusion: FOS supplementation improved the efficacy of OIT in cow's milk allergic mice. Increased levels of Tregs in the MLN and abolished protection against signs of anaphylaxis upon transfer of CD25-depleted cell fractions, suggest a role for Foxp3+ Tregs in the protective effect of OIT + FOS. "
LINK
