154 research outputs found
Carbon nanoparticles in lateral flow methods to detect genes encoding virulence factors of Shiga toxin-producing Escherichia coli
No full textThe use of carbon nanoparticles is shown for the detection and identification of different Shiga toxin-producing Escherichia coli virulence factors (vt1, vt2, eae and ehxA) and a 16S control (specific for E. coli) based on the use of lateral flow strips (nucleic acid lateral flow immunoassay, NALFIA). Prior to the detection with NALFIA, a rapid amplification method with tagged primers was applied. In the evaluation of the optimised NALFIA strips, no cross-reactivity was found for any of the antibodies used. The limit of detection was higher than for quantitative PCR (q-PCR), in most cases between 10 4 and 10 5 colony forming units/mL or 0.1-0.9 ng/¿L DNA. NALFIA strips were applied to 48 isolates from cattle faeces, and results were compared to those achieved by q-PCR. E. coli virulence factors identified by NALFIA were in very good agreement with those observed in q-PCR, showing in most cases sensitivity and specificity values of 1.0 and an almost perfect agreement between both methods (kappa coefficient larger than 0.9). The results demonstrate that the screening method developed is reliable, cost-effective and user-friendly, and that the procedure is fast as the total time required is <1 h, which includes amplification. © 2010 The Author(s).This work was partially supported by the Generalitat Valenciana (BEST/2009/026), the Universidad Politecnica de Valencia (PAID-00-09-2837), and by the Dutch Ministry of Agriculture, Nature and Food Quality (KennisBasis 6 programme). The authors would like to thank Dr. Eva Moller Nielsen at the Danish Veterinary Institute (Copenhagen, Denmark) for providing E. coli control strains and Dr. Lutz Geue (Friedrich-Loeffler-Institut, Wusterhausen, Germany) and Dr. Dorte Dopfer (School of Veterinary Medicine, University of Wisconsin, Madison, WI, USA) for field isolates.Noguera Murray, PS.; Posthuma-Trumpie, G.; Van Tuil, M.; Van Der Wal, F.; De Boer, A.; Moers, A.; Van Amerongen, A. (2011). Carbon nanoparticles in lateral flow methods to detect genes encoding virulence factors of Shiga toxin-producing Escherichia coli. Analytical and Bioanalytical Chemistry. 399:831-838. https://doi.org/10.1007/s00216-010-4334-zS831838399Alocilja EC, Radke SM (2003) Biosens Bioelectron 18:841–846Lazcka O, Campo FJD, Muñoz FX (2007) Biosens Bioelectron 22:1205–1217Nataro JP, Kaper JB (1998) Clin Microbiol Rev 11:142–201Meng J, Doyle MP (1998) Bull Inst Pasteur 96:151–163Karmali MA, Gannon V, Sargeant JM (2010) Vet Microbiol 140:360–370de Boer E, Beumer RR (1999) Int J Food Microbiol 50:119–130Ivnitski D, Abdel-Hamid I, Atanasov P, Wilkins E (1999) Biosens Bioelectron 14:599–624Tokarskyy O, Marshall DL (2008) Food Microbiol 25:1–12Chemburu S, Wilkins E, Abdel-Hamid I (2005) Biosens Bioelectron 21:491–499Rule G, Montagna R, Durst R (1996) Clin Chem 42:1206–1209Ngom B, Guo Y, Wang X, Bi D (2010) Anal Bioanal Chem 397:1113–1135Posthuma-Trumpie GA, Korf J, van Amerongen A (2009) Anal Bioanal Chem 393:569–582Carter DJ, Cary RB (2007) Nucleic Acids Res 35:e74Kalogianni DP, Goura S, Aletras AJ, Christopoulos TK, Chanos MG, Christofidou M, Skoutelis A, Ioannou PC, Panagiotopoulos E (2007) Anal Biochem 361:169–175Litos IK, Ioannou PC, Christopoulos TK, Traeger-Synodinos J, Kanavakis E (2009) Biosens Bioelectron 24:3135–3139Blažková M, Koets M, Rauch P, van Amerongen A (2009) Eur Food Res Technol 229:867–874Mens PF, van Amerongen A, Sawa P, Kager PA, Schallig HD (2008) Diagn Microbiol Infect Dis 61:421–427Gordon J, Michel G (2008) Clin Chem 54:1250–1251Aldus CF, van Amerongen A, Ariens RM, Peck MW, Wichers JH, Wyatt GM (2003) J Appl Microbiol 95:380–389Capps KL, McLaughlin EM, Murray AW, Aldus CF, Wyatt GM, Peck MW, van Amerongen A, Ariens RM, Wichers JH, Baylis CL, Wareing DR, Bolton FJ (2004) J AOAC Int 87:68–77van Amerongen A, Koets M (2005) In: van Amerongen A, Barug D, Lauwaars M (eds) Rapid methods for biological and chemical contaminants in food and feed. Wageningen Academic Publishers, Wageningen, pp 105–216Moreira BG, You Y, Behlke MA, Owczarzy R (2005) Biochem Biophys Res Commun 327:473–484Nielsen EM, Andersen MT (2003) J Clin Microbiol 41:2884–2893Huijsdens XW, Linskens RK, Mak M, Meuwissen SGM, Vandenbroucke-Grauls CMJE, Savelkoul PHM (2002) J Clin Microbiol 40:4423–4427Koets M, Sander I, Bogdanovic J, Doekes G, van Amerongen A (2006) J Environ Monit 8:942–946van Amerongen A, Wichers JH, Berendsen LBJM, Timmermans AJM, Keizer GD, van Doorn AWJ, Bantjes A, van Gelder WMJ (1993) J Biotechnol 30:185–195O’Keeffe M, Crabbe P, Salden M, Wichers J, van Peteghem C, Kohen F, Pieraccini G, Moneti G (2003) J Immunol Methods 278:117–126Posthuma-Trumpie GA, Korf J, van Amerongen A (2008) Anal Bioanal Chem 392:1215–1223Chang LL, Shepherd D, Sun J, Ouellette D, Grant KL, Tang XC, Pikal MJ (2005) J Pharm Sci 94:1427–1444Geue L, Segura-Alvarez M, Conraths FJ, Kuczius T, Bockemuhl J, Karch H, Gallien P (2002) Epidemiol Infect 129:173–185Eurachem/CITAC (2003) EURACHEM/CITAC Guide: The expression of uncertainty in qualitative testing. LGC, Teddington, Middlesex, UK, p 22Ellison SLR, Fearn T (2005) Trac-Trends Anal Chem 24:468–476Gilchrist JM (2009) J Clin Microbiol 62:1045–1053Landis JR, Koch GG (1977) Biometrics 33:159–174Mackinnon A (2000) Comput Biol Med 30:127–134Mil’man BL, Konopel’ko LA (2004) J Anal Chem 59:1128–1141AOAC (2006) Final report and executive summaries from the AOAC International Presidential Task Force on best practices in microbiological methodology. AOAC International, Gaithersburg, Maryland, USA, p 20
Elektromechanisch gedrag van nitrilrubber: Een onderzoek naar de herkomst van elektrostrictie in rubbers
No full textMaterialen die elektromechanisch gedrag vertonen kunnen elektrische en mechanische energie in elkaar omzetten. Het verschijnsel dat een elektrisch veld een mechanische deformatie veroorzaakt wordt elektrostrictie genoemd. Elektrostrictie wordt veroorzaakt door Coulomb-aantrekking tussen gepolariseerde ladingen. In rubbers met een polaire zijgroep is recent een zeer groot elektrostrictie-effect gevonden door Binnendijk [ 27 ] en Van der Ven [ 30 ]. Zij vinden rekken tot tienden procent in middelmatig sterke velden. De elektrostrictie in nitrilrubber is in een statisch elektrisch veld onderzocht. Met een verplaatsingsopnemer is de rek ten gevolge van het veld bepaald. Er zijn experimenten uitgevoerd om het effect op verschillende tijdschalen en temperaturen te onderzoeken. Speciale aandacht is besteed aan het elektrode materiaal. De elektromechanische eigenschappen zijn gekoppeld aan de structuur, de elektrische ( diëlektrische constanten ) en de mechanische (elasticiteit en viscositeit) eigenschappen van het materiaal en de geometrie van het proefstuk. Er is gevonden dat de optredende elektrostrictie evenredig is met het kwadraat van de veldsterkte en dat het een hystereselus vertoont in semi-statische velden. Het effect is opgebouwd uit twee delen. Het eerste is klein en momentaan, het tweede is traag en sterk afhankelijk van de historie van het proefstuk. Er is gevonden det effect groter en sneller wordt bij hogere temperatuur. Door de combinatie van een warmtebehandeling en een elektrisch veld ( polen ) wordt het materiaal schoongeveegd. Er wordt gevonden dat de geleiding en het elektrostrictie-effect afnemen door het polen. Deze afname is definitief. Geconcludeerd is dat het eerste, kleine effect wordt veroorzaakt door moleculaire polarisatie en polarisatie van de nitrildipolen, het tweede door polarisatie van vrije ladingdragers aan grensvlakken ( Maxwell-Wagner effecten ) of door opbouw van ruimteladingswolken. De structuur bestaat uit een matrix van rubber met kristalletjes, waarschijnlijk is dit acrylonitril. De ruimteladingspolarisatie en de glasovergang van de acrylonitrilfase zijn gekoppeld. Mogelijk zijn de ruimteladingen in de glasfase ingevroren en komen vrij bij de glasovergangstemperatuur. Bij hogere temperatuur verdwijnt het elektrostrictie- effect door ruimteladingspolarisatie, waarschijnlijk doordat de elektroden de ladingen doorlaten of absorberen.Applied SciencesScheikundige Technologie en der MateriaalkundeTechnologie van Macromoleculaire Stoffe
Diëlektrische eigenschappen van vloeibaarkristallijne zijketenpolymeren: Literatuur scriptie
No full textZijketen LCP's zijn opgebouwd uit een polymeer met in de zijketens molekulen die een vloeibaarkristallijne fase kunnen vormen (deze noemt men mesogenen). De mesogenen zijn stijve molekulen met een groot dipoolmoment (bijvoorbeeld cyanobip¬henyl). De mesogenen kunnen onafhankelijk van de hoofdketen bewegen. Hierdoor zijn zijketen LCP's quasi hybride materialen. De polymere hoofdketen geeft het materiaal de visco-elastische eigenschappen van een polymeer en het stijve en polaire deel in de zijketen geeft het de eigenschappen van een laagmoleculair vloeibaarkristal. De vloeibaarkristallijne fase van LCP's treedt op boven het glaspunt van het polymeer. In deze fase zijn de zijketens geordend. De oriëntatie van de ordening is in de vloeibaarkristallijne fase van de meeste zijketen LCP's niet te beïnvloeden door uitwendige krachten. Maar vlak onder of op de overgangstemperatuur naar de isotrope vloeistof is de oriëntatie van de vloeibaarkristallijne fase te sturen door het materiaal langzaam af te koelen in een richtend elektrisch of magnetisch veld.Applied SciencesScheikunde en der MateriaalkundeTechnologie van Macromoleculaire Stoffe
Using Gate Leakage Conduction to Understand Positive Gate Bias Induced Threshold Voltage Shift in p-GaN Gate HEMTs
No full textThis work was supported in part by the "Center for the Semiconductor Technology Research" from the Featured Areas Research Center Program within the framework of the Higher Education Sprout Project by the Ministry of Education (MOE) in Taiwan, in part by the National Science and Technology Council (NSTC), Taiwan, under Grant 111-2634-F-A49-008 and Grant 111-2622-8-A49-018-SB, and in part by the Young Scholar Fellowship Program under Grant 111-2636-E-A49-012. The review of this article was arranged by Editor M. Meneghini. (Corresponding author: Tian-Li Wu.
Processing and Properties of Composites based on Thermotropic Liquid Crystalline Polymers and High Density Polyethylene
No full textThis research was concerned with the processing and properties of composites of high density polyethylene (HOPE) and thermotropic liquid crystalline polymers (TLCPs). Strands of HDPE reinforced with TLCPs were generated using a novel dual extruder mixing technique. It was shown that the strength and modulus of the strands improved with increased strand drawing. Post-processing of the blended strands was done by means of compression and injection molding. It was observed that when the fiber aspect ratio dropped, the composite mechanical properties decreased. When pregenerated fibrils were maintain\i during injection molding at temperatures above the matrix melting point, but below the TLCP melting point, microcomposites were obtained. Microcomposites generated at the lowest temperatures had higher tensile properties than found for in situ composites, and similar to glass reinforced HDPE. At 170° C the pregenerated fibers were no longer deformed during injection molding and high aspect ratio fibrils were maintained. The effect of fiber orientation and addition of a compatibilizer were also studied. This study shows it is possible to extrusion blend HOPE with TLCPs, and by optimizing the post-processing conditions, to obtain microcomposites with better properties than in situ composites.Applied SciencesScheikundige Technologie en MateriaalkundeTechnische Macromoleculaire Stoffe
Concept design of a foldable Cold Water pipe for a 10 MW OTEC installation
No full textOcean Thermal Energy Conversion (OTEC) has been heavily researched and developed over the last decade. However, no commercial scale for OTEC has been reached yet. OTEC is a clean and renewable source of energy which utilizes the seawater temperature difference between the upper and deep ocean layers to generate electricity. The heat exchangers and the cold water pipe design are considered to be the most challenging part. The cold water pipe is often stated to be the largest risk. The installation of the cold water pipe, the high investment costs of the cold water pipe and the large forces acting upon the cold water pipe are crucial factors for the future success of OTEC. In this thesis, a new kind of cold water pipe concept is introduced. The FLEX-hose concept consists of a thin sheet of nylon, supported by concrete rings and polyester cables. The total length of the foldable concept design is 1000 m. The nylon sheet is attached to the concrete rings and the cables are attached to the concrete rings. The cables run through the concrete rings and can be used during installation to lower the pipe. Deployment of the foldable pipe is expected to be relatively easy thereby lowering the installation costs. The Multi Criteria Analysis performed in this thesis show the FLEX-hose foldable concept to be attractive compared to a foldable spiral concept, a flexible composite concept, a rigid composite pipe and a HDPE pipe. However, the inclination angle occurring while pumping may not become significant, meaning above 7.5 degrees, since this will lead to lower energy efficiency. In addition, no current design is available on the market, meaning heavy research and development is needed for the foldable concept to succeed. Possible challenges for the FLEX-hose concept that have been established through this research include instability occurring due to buckling and a pressure drop becoming larger than 0.6 bar, thereby significantly reducing the net power of the OTEC plant. The maximum allowed angle of inclination of the sheet to stay below 0.6 bar is calculated to be 7.5 degrees at a flow speed of 2 m/s. During pumping a discharge of 20.000 kg/s is pumped through a thin walled pipe with a diameter of 3.5 m, which leads to a radial displacement of the nylon sheet. Collapse and too significant deformations of the thin walled sheet are prevented by applying 10 MN of pre-tension in the thin walled sheet. However, in order for the nylon sheet to stay in the linear elastic regime, the calculated wall thickness is 0.04 m, thereby making foldability questionable. A total of 200 concrete rings is present in the design, one every 5 m over the total length of 1000 m of the pipe. In addition, a large clump weight of 12 MN is needed at the bottom of the pipe. The total system weight of the foldable pipe with concrete rings is calculated to be 1840 mT, which could be installed by an offshore installation vessel. Finally, creep has also been established to be a challenge due to the life-time of 30 years for the cold water pipe. A synthetic plastic material such as nylon experiences relaxation of the material when stressed for a longer period of time, leading to large deformations.Offshore and Dredging Engineerin
Deformation and -theoretic Index Formulae on Boundary Groupoids
No full textBoundary groupoids were introduced by the second author, which can be used to model many analysis problems on singular spaces. In order to investigate index theory on boundary groupoids, we introduce the notion of {\em a deformation from the pair groupoid}.Under the assumption that a deformation from the pair groupoid exists for Lie groupoid , we construct explicitly a deformation index map relating the analytic index on and the index on the pair groupoid. We apply this map to boundary groupoids of the form , where is an exponential Lie group, to obtain index formulae for (fully) elliptic (pseudo)-differential operators on , with the aid of the index formula by M. J. Pflaum, H. Posthuma, and X. Tang. These results recover and generalize our previous results for renormalizable boundary groupoids via the method of renormalized trace
Ein gefährdetes Kulturgut: Neue Perspektiven für die Konservierung von Goldleder in den Niederlanden
No full textDas 17. und 18. Jahrhundert gilt als „Goldenes Zeitalter“ des Goldleders in den Nord- und Südniederlanden. Obwohl dieses Material einst ähnlich berühmt war wie die Delfter Keramik, ist unglücklicherweise viel davon verloren gegangen. Gründe dafür sind Renovierungen, Materialzersetzungen und fehlendes Wissen über konservatorische Behandlungsmöglichkeiten. Technische Kunstwissenschaftler, Restauratoren und Wissenschaftler arbeiten gemeinsam daran, diese Objekte und ihre kulturelle Bedeutung für zukünftige Generationen zu erhalten. The ‘Golden Age’ for gilt leather in the Northern and Southern Netherlands was in the 17th and 18th centuries. Unfortunately much of this material, even though it once had a similar fame to Delftware, has been lost through a variety of factors, including renovations, material degradation and limited knowledge in applying conservation treatments. The current generation of (technical) art historians, conservators and scientists are working together to ensure the preservation of these objects and their cultural meaning for future generations.Structural Integrity & Composite
Gilt Leather Artefacts: White Paper on Material Characterization and Improved Conservation Strategies within NICAS
No full textDue to its sensitivity, the conservation and upkeep of gilt leather isoften underestimated. It can sincerely be considered as endangeredcultural heritage. This publication describes the current state ofknowledge from the perspectives of Technical Art History, MaterialDynamics, Conservation and Diagnostics, and sets out researchdirections for 2017-2025
A new dynamic N2O reduction system based on Rh/ceria-zirconia: from mechanistic insight towards a practical application
No full textSimultaneous reduction of N2O in the presence of co-existing oxidants, especially NO, from industrial plants, is a challenging task. This study explores the applications of a hydrocarbon reduced Rh/Zr stabilized La doped ceria (Rh/CLZ) catalyst in N2O abatement from oxidant rich industrial exhaust streams e.g. NO, CO2, and O2. The reaction mechanism was studied by the temporal analysis of products. The obtained results revealed that hydrocarbon pretreatment led to the creation of ceria oxygen vacancies and the formation of carbon deposits on the Rh/CLZ catalyst surface. These ceria oxygen vacancies are the active sites for the selective reduction of N2O into N2, while the dissociated O atoms from N2O fill the ceria oxygen vacancies. The oxidation of the deposited carbon via the lattice ceria oxygen generates new ceria oxygen vacancies, thereby extending the catalytic cycle. The reduction of N2O over C3H6 reduced Rh/CLZ is a process combining oxygen vacancy healing and deposited carbon oxidation. The results obtained from fixed-bed reactor experiments demonstrated that the hydrocarbon reduced Rh/CLZ catalyst provided a unique and extraordinary N2O abatement performance in the presence of co-existing competing oxidants (reactivity order: N2O ∼ NO > O2 > CO2 ∼ H2O).ChemE/Catalysis Engineerin
- …
