Search results for "bioengineering"
showing 10 items of 1963 documents
Mapping of local conductivity variations on fragile nanopillar arrays by scanning conductive torsion mode microscopy.
2010
A gentle method that combines torsion mode topography imaging with conductive scanning force microscopy is presented. By applying an electrical bias voltage between tip and sample surface, changes in the local sample conductivity can be mapped. The topography and local conductivity variations on fragile free-standing nanopillar arrays were investigated. These samples were fabricated by an anodized aluminum oxide template process using a thermally cross-linked triphenylamine-derivate semicondcutor. The nanoscale characterization method is shown to be nondestructive. Individual nanopillars were clearly resolved in topography and current images that were recorded simultaneously. Local current−…
Toward Single Electron Nanoelectronics Using Self-Assembled DNA Structure
2016
DNA based structures offer an adaptable and robust way to develop customized nanostructures for various purposes in bionanotechnology. One main aim in this field is to develop a DNA nanobreadboard for a controllable attachment of nanoparticles or biomolecules to form specific nanoelectronic devices. Here we conjugate three gold nanoparticles on a defined size TX-tile assembly into a linear pattern to form nanometer scale isolated islands that could be utilized in a room temperature single electron transistor. To demonstrate this, conjugated structures were trapped using dielectrophoresis for current-voltage characterization. After trapping only high resistance behavior was observed. However…
Size filtering effect in vertical stacks of In(Ga)As/GaAs self-assembled quantum rings
2006
3 páginas, 3 figuras.
Lipid nanocarriers containing esters prodrugs of Flurbiprofen. Preparation, physical-chemical characterization and biological studies.
2013
In this paper, the preparation, chemical-physical, technological and in vitro characterization of nanostructured lipid carriers (NLC) carrying R-flurbiprofen ester prodrugs, were analyzed for a potential pharmaceutical application. R-flurbiprofen was chosen as a model drug because it has been found to play an effective role in counteracting secretases involved in neurodegenerative diseases, although it does not cross the Blood Brain Barrier (BBB). In this study, two R-flurbiprofen ester prodrugs (ethyl and hexyl) were successfully synthesized and entrapped into non-pegylated and pegylated NLC. The obtained systems showed average diameters in the colloidal size range, negative zeta potential…
Fullerite crystal thermodynamic characteristics and the law of corresponding states.
2010
The existence of single-wall carbon nanotubes in organic solvents in the form of clusters is discussed. A theory is developed based on a bundlet model, which enables describing the cluster-size distribution function. Comparison of calculated solubilities with experiments would permit obtaining energetic parameters, characterizing the interaction of a nanotube with its surrounding. Fullerenes and nanotubes are objects whose behaviour in many physical situations is characterized by peculiarities, which show up in that these systems represent the only soluble forms of carbon, what is related to their molecular structures. The fullerene molecule is a virtually uniform closed spherical-spheroida…
Controlling electrical percolation in multicomponent carbon nanotube dispersions
2011
Carbon nanotube reinforced polymeric composites can have favourable electrical properties, which make them useful for applications such as flat-panel displays and photovoltaic devices. However, using aqueous dispersions to fabricate composites with specific physical properties requires that the processing of the nanotube dispersion be understood and controlled while in the liquid phase. Here, using a combination of experiment and theory, we study the electrical percolation of carbon nanotubes introduced into a polymer matrix, and show that the percolation threshold can be substantially lowered by adding small quantities of a conductive polymer latex. Mixing colloidal particles of different …
Launching propagating surface plasmon polaritons by a single carbon nanotube dipolar emitter.
2011
International audience; We report on the excitation of propagating surface plasmon polaritons in thin metal films by a single emitter. Upon excitation in the visible regime, individual semiconducting single-walled carbon nanotubes are shown to act as directional near-infrared point dipole sources launching propagating surface plasmons mainly along the direction of the nanotube axis. Plasmon excitation and propagation is monitored in Fourier and real space by leakage radiation microscopy and is modeled by rigorous theoretical calculations. Coupling to plasmons almost completely reshapes the emission of nanotubes both spatially and with respect to polarization as compared to photoluminescence…
Surfactant-Dependent Exciton Mobility in Single-Walled Carbon Nanotubes Studied by Single-Molecule Reactions
2010
Measurements of stepwise photoluminescence quenching in individual, (n,m)-selected single-walled carbon nanotubes (SWCNTs) undergoing chemical reaction have been analyzed to deduce mobilities of optically generated excitons. For (7,5) nanotubes, the mean exciton range varies between approximately 140 and 240 nm for different surfactant coatings and correlates weakly with nanotube PL intensity. The results are consistent with a model of localized SWCNT excitons having substantial diffusional mobility along the nanotube axis.
In situ nucleation of carbon nanotubes by the injection of carbon atoms into metal particles.
2007
The synthesis of carbon nanotubes (CNTs) of desired chiralities and diameters is one of the most important challenges in nanotube science and achieving such selectivity may require a detailed understanding of their growth mechanism. We report the formation of CNTs in an entirely condensed phase process that allows us, for the first time, to monitor the nucleation of a nanotube on the spherical surface of a metal particle. When multiwalled CNTs containing metal particle cores are irradiated with an electron beam, carbon from graphitic shells surrounding the metal particles is ingested into the body of the particle and subsequently emerges as single-walled nanotubes (SWNTs) or multiwalled nan…
Template electrosyntesis of CeO2 nanotubes
2007
Nanotube arrays of CeO2 were produced in a single step by potentiostatic electrochemical deposition from a non-aqueous electrolyte, using anodic alumina membrane templates. The CeO2 nanotubes showed a polycrystalline structure, and they were assembled in the membrane nanochannels. The nanotubes had somewhat uniform diameters, with an average external value of about 210 nm, and a maximum length of about 60 µm; the latter parameter was controlled by the electrodeposition time. Each single nanotube was found to consist of crystalline grains having a size of about 3 nm. Raman analysis shows that these CeO2 nanotubes are suitable for catalytic applications.