Search results for "carrier"
showing 10 items of 1256 documents
Microfluidic Pumping by Micromolar Salt Concentrations
2017
An ion-exchange-resin-based microfluidic pump is introduced that utilizes trace amounts of ions to generate fluid flows. We show experimentally that our pump operates in almost deionized water for periods exceeding 24h and induces fluid flows of um/s over hundreds of um. This flow displays a far-field, power-law decay which is characteristic of two-dimensional (2D) flow when the system is strongly confined and of three-dimensional (3D) flow when it is not. Using theory and numerical calculations we demonstrate that our observations are consistent with electroosmotic pumping driven by umol/L ion concentrations in the sample cell that serve as 'fuel' to the pump. Our study thus reveals that t…
Effect of conductivity of hole injection layer on the performance of a blue light emitting solution processable OLED
2005
The performance of blue emitting OLED devices, using a polyspiro as blue light emitting polymer, were studied as a function of the conductivity of a novel hybrid hole injection material. The hole injection material is based on a polyarylamine using a molecular magnet as oxidant. The charge density and the luminance of the devices changed considerably with increasing conductivity of the hole injection layer. The change in device performance can be attributed to a change from a hole limited device to a balanced charge carrier device and eventually to an electron limited device. The performance of the optimized device configuration is significantly improved with respect to a device making use …
Loading of polymer nanocarriers: Factors, mechanisms and applications
2014
Abstract The progress in synthetic polymer chemistry has allowed the precise design of hybrid and multifunctional colloidal particles, which differ in type, size and shape, thus enhancing their possible applications as target-oriented carriers of low and high molar mass active species. This survey discusses the basic principles and factors, associated with the process of loading of polymeric nanoparticles. For the purpose of this review, the polymeric nano-carriers are divided into five most studied types: micelles, nanogels, capsules (incl. vesicles), dendrimers, and hybrid nanoparticles with porous cores. Factors influencing the loading are described and their importance discussed. An imp…
Synthesis and bio-functionalization of magnetic nanoparticles for medical diagnosis and treatment
2011
The synthesis of multifunctional magnetic nanoparticles (NPs) is a highly active area of current research located at the interface between materials science, biotechnology and medicine. By virtue of their unique physical properties magnetic nanoparticles are emerging as a new class of diagnostic probes for multimodal tracking and as contrast agents for MRI. Furthermore, they show great potential as carriers for targeted drug and gene delivery, since reactive agents, such as drug molecules or large biomolecules (including genes and antibodies), can easily be attached to their surface. On the other hand, the fate of the nanoparticles inside the body is mainly determined by the interactions wi…
REGULATION OF CATIONIC AMINO ACID TRANSPORT: The Story of the CAT-1 Transporter
2004
▪ Abstract The discovery of the function of the receptor for the ecotropic retrovirus as a membrane transporter for the essential amino acids lysine and arginine was a landmark finding in the field of molecular nutrition. This finding indicated that cationic amino acid transporters (CATs) act pathologically as viral receptors. The importance of this transporter was further supported by knockout mice that were not viable after birth. CAT-1 was the first amino acid transporter to be cloned; several other CATs were later characterized biochemically and molecularly. These transporters mediate the bidirectional transport of cationic amino acids, thus supporting important metabolic functions, s…
Phase Transition of SBN: Ce Studied by Anisotropic Holographic Scattering
1991
Light scattering phenomena in (Sr0.61Ba0.39) Nb2O6:Ce are investigated from room temperature to the phase transition temperature. Temperature dependence and sign of the birefringence are determined from anisotropic holographic scattering at a wavelength of 514.5 nm. The majority charge carriers are electrons. Zwischen Zimmertemperatur und der Phasenubergangstemperatur werden Lichtstreuphanomene in (Sr0,61Ba0,39)Nb2O6:Ce untersucht. Aus der anisotropen holographischen Streuung bei einer Wellenlange von 514,5 nm werden Temperaturabhangigkeit und Vorzeichen der Doppelbrechung bestimmt. Die Majoritatsladungstrager sind Elektronen.
New Perspectives of HPMA-based Copolymers Derived by Post-Polymerization Modification
2014
Poly[N-(2-hydroxypropyl) methacrylamide] (HPMA) was one of the first polymers applied as polymer drug conjugate in the clinics. Since then many attempts have been made to expand the functionality of HPMA-based copolymers from advanced synthetic pathways to multiple biomedical applications. This Feature Article highlights multifunctional HPMA based copolymers prepared by controlled radical polymerization and subsequent post-polymerization modification of activated ester precursor polymers via aminolysis. This approach combines precise control of the polymer's microstructure (molecular weight, dispersity, block copolymer formation, end group functionalization) with an easy introduction of var…
pH-sensitive hydrogel based on a novel photocross-linkable copolymer.
2004
A pH sensitive hydrogel has been prepared by a UV irradiation technique. Starting polymer was the PHM (poly hydroxyethylaspartamide methacrylated) obtained from polyaspartamide (PHEA) partially derivatized with methacrylic anhydride (MA). This new copolymer has been further derivatized with succinic anhydride (SA) to obtain PHM-SA that has been cross-linked by UV irradiation to form a pH sensitive hydrogel. The network, recovered after washing as a powder, has been been characterized by FT-IR spectrophotometry and particle size distribution analysis. Moreover, to have information about water affinity of the prepared sample, swelling measurements have been carried out in aqueous media mimick…
Relaxation of electron-hole pairs and scintillation mechanism in alkali halide crystals
1997
Abstract The mechanism of the ionizing radiation energy transfer from host lattice to luminescence centers is discussed taking into account the results of the recent experimental investigations of electron-hole pair relaxation in alkali iodide crystals. The high scintillation yield in CsI-Tl, CsI-Na and partially in Nal-Tl crystals is explained by the process of the motion and capture of a one-center self-trapped exciton by impurity ions.
Strontium Insertion in Methylammonium Lead Iodide: Long Charge Carrier Lifetime and High Fill-Factor Solar Cells.
2016
The addition of Sr2+ in CH3 NH3 PbI3 perovskite films enhances the charge carrier collection efficiency of solar cells leading to very high fill factors, up to 85%. The charge carrier lifetime of Sr2+ -containing perovskites is in excess of 40 μs, longer than those reported for perovskite single crystals.