Search results for "bioengineering"
showing 10 items of 1963 documents
Supramolecular capping-ligand effect of lamellar silica mesostructures for the one-pot synthesis of highly dispersed ZnO nanoparticles
2006
ZnO?SiO2 lamellar nanocomposites with high zinc content (5?Si/Zn?50) have been synthesized through a one-pot surfactant-assisted procedure from aqueous solution and starting from molecular atrane complexes of Zn and Si as inorganic hydrolytic precursors. This approach allows optimization of the dispersion of the ZnO nanodomains in the silica sheets. The nature of the layered silica materials has been confirmed by x-ray diffraction. Spectroscopic (ultraviolet?visible and photoluminescence) study of these layered silica materials shows that, regardless of the Si/Zn ratio, Zn atoms are organized in well-dispersed, uniform ZnO nanodomains (about 1.2?nm) partially embedded within the silica shee…
One-pot synthesis of PbS NP/sulfur-oleylamine copolymer nanocomposites via the copolymerization of elemental sulfur with oleylamine
2014
A novel synthetic and processing strategy for converting elemental sulfur into polymeric and nanocomposite materials is reported. We describe a facile one-pot reaction using elemental sulfur and oleylamine as comonomers to prepare high sulfur content copolymers and lead sulfide nanoparticle (PbS NP) nanocomposites. This process enables the preparation of solution processable copolymers and nanocomposites, where the loading and dispersion of PbS NP inclusions could be precisely controlled. We demonstrate the dual roles of oleylamine with sulfur for both the copolymerization of sulfur copolymers as well as the in situ synthesis of PbS NPs in a one-pot fashion.
The zero field self-organization of cobalt/surfactant nanocomposite thin films
2009
Cobalt nanostructures have been prepared by a chemical route based on the Co(II) reduction in the confined space of cobalt bis(2-ethylhexyl)sulfosuccinate (Co(DEHSS)(2)) reverse micelles dispersed in n-heptane. This procedure involves the rapid formation of surfactant softly coated Co nanostructures followed by a slow separation process of the magnetic-field responsive Co/surfactant nanocomposites from the liquid phase. The detailed structure of thin films of the Co/surfactant nanocomposites has been investigated by scanning force microscopy (SFM). The thin films were characterized by different anisotropic features. Micrometric long domains of self-aligned ellipsoidal NPs (tens of nanometer…
Memory effects in MOS devices based on Si quantum dots
2003
Silicon quantum dots have been deposited on top of a 3-nm tunnel oxide by Low Pressure Chemical Vapour Deposition (LPCVD) and coated with a 7-nm Chemical Vapour Deposited (CVD) oxide. This stack was then incorporated in Metal-Oxide-Semiconductor structure and used as floating gate of a memory cell. The presence of 3 nm of tunnel oxides allows the injection of the charge by direct tunnel (DT) using low voltages for both program and erase operations. The charge stored in the quantum dots is able to produce a well-detectable flat band shift in the capacitors or, equivalently, a threshold voltage shift in the transistors. Furthermore, due to the presence of SiO 2 between the grains, the lateral…
Programming options for nanocrystal MOS memories
2003
Nanocrystal memories represent a promising candidate for the scaling of FLASH memories. In these devices, the charge is not stored in a continuous floating gate but in a discontinuous layer composed by numerous discrete silicon quantum dots well separated one from the other.The nanocrystals of radius of few nanometers are realized by chemical vapor deposition (CVD) of silicon on the tunnel oxide of 2.8 nm of thickness. These islands have been coated with a control oxide of 7 nm formed by CVD and incorporated in Metal-Oxide-Semiconductor structure. The devices are programmed and erased by tunnelling using low voltages and fast times. In addition, the programming can be easily achieved also b…
Superconducting properties of in-plane W-C nanowires grown by He+ Focused Ion Beam Induced Deposition
2021
Focused ion beam induced deposition (FIBID) is a nanopatterning technique that uses a focused beam of charged ions to decompose a gaseous precursor. So far, the flexible patterning capabilities of FIBID have been widely exploited in the fabrication of superconducting nanostructures, using the W(CO)6 precursor mostly in combination with a focused beam of Ga+ ions. Here, the fabrication and characterization of superconducting in-plane tungsten-carbon (W-C) nanostructures by He+ FIBID of the W(CO)6 precursor is reported. A patterning resolution of 10 nm has been achieved, which is virtually unattainable for Ga+ FIBID. When the nanowires are patterned with widths of 20 nm and above, the deposit…
Nanostructured medical sutures with antibacterial properties
2014
Bacterial repellence in suture materials is a desirable property that can potentially improve the healing process by preventing infection. We describe a method for generating nanostructures at the surface of commercial sutures of different composition, and their potential for preventing biofilm formation. We show how bacteria attachment is altered in the presence of nanosized topographies and identify optimum designs for preventing it without compromising biocompatibility and applicability in terms of nanostructure robustness or tissue friction. These studies open new possibilities for flexible and cost-effective realization of topography-based antibacterial coatings for absorbable biomedic…
Raman Monitoring of Strain Induced Effects in Mechanically Deposited Single Layer Graphene
2012
Graphene is a two dimensional building block for carbon allotropes of many other dimensionality and shows remarkable electronic and optical properties that attract enormous interest. In order to make graphene useful for real technology, a control of its electronic and mechanical properties is a must. In this respect, a crucial step for the use of graphene layers in device fabrication is the deposition onto suitable substrates, understanding the interaction with them. Micromechanical cleavage of graphite has been used to produce high-quality graphene sheets. The aim of this work is to study the strain effects induced in graphene by the deposition process using Raman spectroscopy and scanning…
Influence of cerium content and heat treatment on Ce:YAG@glass wool nanostructures
2019
The paper reports the influence of cerium content and heat treatment on composition, structural features and optical properties of nanostructures constituted by a layer of Ce:YAG nanoparticles on glass wool (Ce:YAG@GW). The Ce:YAG@GW nanostructures were obtained embedding the glass wool (GW) in a gel-like precursor and calcining at 800 and 900 °C. Gel-like precursor of urea glass route (UGR) method has been used to prepare both nanostructures and Ce:YAG nanoparticles prepared as references. Structural properties were investigated by using X-ray diffraction (XRD) and infrared spectroscopy (IR). Results showed that the composition of the final products strongly depends both on the cerium cont…
Single Out-of-Resonance Dielectric Nanoparticles as Molecular Sensors.
2021
Light scattering from single nanoparticles and nanostructures is a commonly used readout method for nanosensors. Increasing the spectral sensitivity of resonant nanosensors to changes in their local surrounding has been the focus of many studies. Switching from spectral to intensity monitoring allows one to investigate nonresonant or out-of-resonance dielectric nanoparticles. Here, we systematically compared such dielectric silica nanoparticles with plasmonic gold nanorods by deriving analytical expressions and by performing experiments. The experiments show a similar sensitivity for the detection of an adsorbate layer for both particle types, which is in good agreement with theory. The fla…