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  • nanoparticles  (37)
  • biocompatibility  (35)
  • Technik allgemein  (72)
  • 1
    ISSN: 1572-8781
    Schlagwort(e): MPC ; BMA ; AMPS ; biocompatibility ; cellulose triacetate ; diffusion-limiting effect ; glucose sensor ; needle type ; glucose oxidase ; serum ; whole blood
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Technik allgemein
    Notizen: Abstract A multifunctional membrane with biocompatibility, diffusion-limiting effect, and the ability to curtail the responses of an H2O2 electrode to ascorbate and urate was prepared. It was composed of MB, AB, and CTA, where MB is the copolymer of 2-methacryloyloxyethyl phosphorylcholine (MPC) and n-butylmethacrylate (BMA), AB is the copolymer of acrylamide-2-methylpropane sulfonic acid (AMPS) and BMA, CTA is cellulose triacetate. Investigation of the biocompatibility of this membrane showed that, compared with CTA, relatively few platelets bound to it. The membrane was coated onto the working electrode of a needle-type glucose sensor on which immobilized glucose oxidase membrane has been coated. The sensor did not respond to ascorbate and urate at their concentration normally encountered in blood. Its response was not inhibited by metal ions in blood at usual concentration. The sensor exhibited superior thermostability in addition to a rapid response (〈90 seconds in batch operation), good reproducibility (RE〈5%), good stability (more than 36 hours continuously in heparinized whole blood), and a wide dynamic range (5–650 mg/dl glucose). The sensor was used to determine glucose in serum. The data obtained from the sensor showed good agreement with that from a clinical autoanalyzer (R=0.973).
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    ISSN: 1572-896X
    Schlagwort(e): nanoparticles ; thermal plasma ; nanostructural film ; particle deposition ; silicon carbide ; film hardness
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik , Technik allgemein
    Notizen: Abstract Nanostructured silicon carbide films have been deposited on molybdenum substrates by hypersonic plasma particle deposition. In this process a thermal plasma with injected reactants (SiCl4 and CH4) is expanded through a nozzle leading to the nucleation of ultrafine particles. Particles entrained in the supersonic flow are then inertially deposited in vacuum onto a temperature-controlled substrate, leading to the formation of a consolidated film. In the experiments reported, the deposition substrate temperature Ts has ranged from 250°C to 700°C, and the effect of Ts on film morphology, composition, and mechanical properties has been studied. Examination of the films by scanning electron microscopy has shown that the grain sizes in the films did not vary significantly with Ts. Micro-X-ray diffraction analysis of the deposits has shown that amorphous films are deposited at low Ts, while crystalline films are formed at high Ts. Rutherford backscattering spectrometry has indicated that the films are largely stoichiometric silicon carbide with small amounts of chlorine. The chlorine content decreases from 8% to 1.5% when the deposition temperature is raised from 450°C to 700°C. Nanoindentation and microindentation tests have been performed on as-deposited films to measure hardness, Young's modulus and to evaluate adhesion strength. The tests show that film adhesion, hardness and Young's modulus increase with increasing Ts. These results taken together demonstrate that in HPPD, as in vapor deposition processes, the substrate temperature may be used to control film properties, and that better quality films are obtained at higher substrate temperatures, i.e. Ts≈700°C.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    ISSN: 1572-896X
    Schlagwort(e): emulsion ; combustion ; ceramic ; nanoparticles ; synthesis ; barium titanate powder
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik , Technik allgemein
    Notizen: Abstract The emulsion combustion method (ECM), a novel powder production process, was originally developed to synthesize nano-structured metal-oxide powders. Metal ions in the aqueous droplets were rapidly oxidized by the combustion of the surrounding flammable liquid. The ECM achieved a small reaction field and a short reaction period to fabricate the submicron-sized hollow ceramic particles with extremely thin wall and chemically homogeneous ceramic powder. Alumina, zirconia, zirconia–ceria solid solutions and barium titanate were synthesized by the ECM process. Alumina and zirconia powders were characterized to be metastable in crystalline phase and hollow structure. The wall thickness of alumina was about 10 nm. The zirconia–ceria powders were found to be single-phase solid solutions for a wide composition range. These powders were characterized as equiaxed-shape, submicron-sized chemically homogeneous materials. The powder formation mechanism was investigated through the synthesis of barium titanate powder with different metal sources.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Journal of nanoparticle research 1 (1999), S. 267-276 
    ISSN: 1572-896X
    Schlagwort(e): nanoparticles ; microemulsions ; reaction engineering ; formation model ; simulation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik , Technik allgemein
    Notizen: Abstract Engineering aspects of the preparation of palladium nanoparticles in non-ionic w/o-microemulsions are examined. In order to achieve reproducible synthesis conditions a semi-batch reactor with a standardized design is used. Influences of the stirring rate and of different ways of concentration control on the product properties are observed. For reproducible synthesis it is important to establish appropriate and defined preparation conditions. Monodisperse palladium particles of around 5 nm size are obtained by adding the microemulsion containing the palladium salt at a constant feed rate to the precharged microemulsion containing the reducing agent. A quantitative kinetic model is proposed to describe particle formation in microemulsions. Unknown parameters of the model have been estimated by independent examinations or can be achieved by fitting to the experimental data.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Journal of nanoparticle research 1 (1999), S. 349-352 
    ISSN: 1572-896X
    Schlagwort(e): alcohol–aqueous salt solutions ; ZrO2 ; nanoparticles ; aging
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik , Technik allgemein
    Notizen: Abstract Parameters that influence ZrO2 (3-mol% Y2O3 stabilized) nanoparticles prepared by heating of alcohol–aqueous salt solutions were investigated. It revealed that the kind of alcohol used significantly affected the particle size and morphology of the as synthesized nano-ZrO2 powders. The ratio of alcohol to water (R/H) was also important to conduct the gelation process. The dispersion and sintering behavior of the powder could be optimized via aging. By carefully controlling the process, weakly agglomerated ZrO2 nanoparticles with an average particle size of 13-nm (TEM) were achieved. The classical DLVO theory was employed to clarify the effect of solvent on powder morphology, an aging mechanism was proposed as well.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Journal of nanoparticle research 1 (1999), S. 411-418 
    ISSN: 1572-896X
    Schlagwort(e): isopycnic centrifugation ; buoyant density ; drug delivery ; nanoparticles ; sucrose linear gradient
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik , Technik allgemein
    Notizen: Abstract The development of polymer nanoparticles as drug carriers requires numerous steps including several in vitro evaluations in cell cultures and biocompatibility. To perform these experiments, it is crucial to express the particle concentration as the number of particles per volume unit or as the particle surface area. Calculation of these suspension characteristics can be perfomed knowing the size and the density of the nanoparticles as well as the polymer concentration. While particle size and polymer concentration are parameters being determined routinely, this study proposes to measure the density of the nanoparticle drug carriers by isopycnic centrifugation using linear sucrose gradients. The method was found to be very reproducible and it presents the advantage of being applied on a small sample of nanoparticles.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    ISSN: 1572-896X
    Schlagwort(e): nanoparticles ; measurements ; instrumentation ; standards ; aerosols ; colloids
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik , Technik allgemein
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    ISSN: 1572-896X
    Schlagwort(e): nanoparticles ; pulse height analysis ; aerosol ; particle size ; condensation particle counter ; light scattering
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik , Technik allgemein
    Notizen: Abstract Several of the most common methods for measuring nanoparticle size distributions employ the ultrafine condensation particle counter (UCPC) for detection purposes. Among these methods, the pulse height analysis (PHA) technique, in which the optical response of the UCPC detector is related to initial particle diameter in the 3–10 nm range, prevails in applications where fast sampling is required or for which concentrations of nanoparticles are frequently very low. With the PHA technique, white light is required for particle illumination in order to obtain a monotonic relationship between initial particle diameter and optical response (pulse height). However, the popular, commercially available TSI Model 3025A UCPC employs a laser for particle detection. Here, we report on a novel white-light detection system developed for the 3025A UCPC that involves minimal alteration to the instrument and preserves normal counting operation. Performance is illustrated with pulse height spectra produced by differential mobility analyzer (DMA) – generated calibration aerosols in the 3–50 nm range.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Journal of nanoparticle research 2 (2000), S. 199-204 
    ISSN: 1572-896X
    Schlagwort(e): nanoscale heat transfer ; nanoparticles ; nanowires ; phonons ; superlattices ; thermal conductivity ; thin films ; microscale effects
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik , Technik allgemein
    Notizen: Abstract Heat conduction in nanostructures differs significantly from that in macrostructures because the characteristic length scales associated with heat carriers, i.e., the mean free path and the wavelength, are comparable to the characteristic length of nanostructures. In this communication, particularities associated with phonon heat conduction in nanostructures, the applicability of the Fourier law, and the implications of nanoscale heat transfer effects on nanotechnology are discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Journal of nanoparticle research 2 (2000), S. 183-190 
    ISSN: 1572-896X
    Schlagwort(e): superlattices ; colloidal particles ; Langmuir–Blodgett films ; electrostatic complexation ; air-water interface ; nanoparticles
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik , Technik allgemein
    Notizen: Abstract The formation of nanoparticle multilayer films by electrostatic immobilization of surface-modified colloidal particles at the air–water interface has been recently demonstrated by us. In this paper, we extend our study to show that multilayer assemblies consisting of metal particles of different chemical nature (hetero-colloidal particle superlattices) and size can be deposited by the versatile Langmuir–Blodgett technique. Multilayer films consisting of a different number of bilayers of gold and silver colloidal particles have been deposited and characterized using quartz crystal microgravimetry and UV–visible spectroscopy measurements. It is observed that while layer-by-layer deposition of the different colloidal particle assemblies is possible by this technique without a detectable variation in the cluster density in the different layers, a degree of post-deposition reorganization of the clusters occurs in the film. In addition to this aging behavior, the effect of different organic solvents on the reorganization process has also been studied.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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