Search results for "fabrication"
showing 10 items of 460 documents
Propolis-Based Nanofiber Patches to Repair Corneal Microbial Keratitis
2021
In this research, polyvinyl-alcohol (PVA)/gelatin (GEL)/propolis (Ps) biocompatible nanofiber patches were fabricated via electrospinning technique. The controlled release of Propolis, surface wettability behaviors, antimicrobial activities against the S. aureus and P. aeruginosa, and biocompatibility properties with the mesenchymal stem cells (MSCs) were investigated in detail. By adding 0.5, 1, and 3 wt.% GEL into the 13 wt.% PVA, the morphological and mechanical results suggested that 13 wt.% PVA/0.5 wt.% GEL patch can be an ideal matrix for 3 and 5 wt.% propolis addition. Morphological results revealed that the diameters of the electrospun nanofiber patches were increased with GEL (from…
van der Waals heterostructures based on atomically-thin superconductors
2021
Van der Waals heterostructures (vdWHs) allow the assembly of high-crystalline two-dimensional (2D) materials in order to explore dimensionality effects in strongly correlated systems and the emergence of potential new physical scenarios. In this work, it is illustrated the feasibility to integrate 2D materials in-between 2D superconductors. Particularly, it is presented the fabrication and electrical characterization of vertical vdWHs based on air-unstable atomically-thin transition metal dichalcogenides formed by NbSe2/TaS2/NbSe2 stacks, with TaS2 being the insulator 1T-TaS2 or the metal 2H-TaS2. Phase transitions as 1T-TaS2 charge density wave and NbSe2 superconductivity are detected. An …
Photoelectrochemical Evidence of Cu2O/TiO2 Nanotubes Hetero-Junctions formation and their Physicochemical Characterization
2014
Cu2O/TiO2 nanotubes heterojunctions were fabricated by electrochemical deposition of cuprous oxide on TiO2 nanotubes arrays grown by anodizing. X-ray diffraction and Raman Spectroscopy analysis allows for identification of Cu2O, whose morphological features were studied by Scanning Electron Microscopy as a function of the charge circulated during the electrodeposition step. Photoelectrochemical measurements in aqueous solutions evidenced a red shift of the light absorption threshold of TiO2 nanotubes due to the presence of cuprous oxide even for very low circulated charges, while electrochemical impedance measurements proved a significant reduction of the electrode impedance due the presenc…
On-line monitoring of one-step laser fabrication of micro-optical components
2002
The use of an on-line monitoring method based on photoelasticity techniques for the fabrication of micro-optical components by means of controlled laser heating is described. From this description it is possible to show in real time the mechanical stresses that form the microelement. A new parameter, stressed area, is introduced that quantifies the stresses of a microelement during its fabrication, facilitating a deeper understanding of the physical phenomena involved in the process as well as being a useful test of quality. It also permits the stress produced in the manufacturing process and the optical properties of the final microelement to be correlated. The results for several microlen…
Active photonic devices based on colloidal semiconductor nanocrystals and organometallic halide perovskites
2016
Semiconductor nanocrystals have arisen as outstanding materials to develop a new generation of optoelectronic devices. Their fabrication under simple and low cost colloidal chemistry methods results in cheap nanostructures able to provide a wide range of optical functionalities. Their attractive optical properties include a high absorption cross section below the band gap, a high quantum yield emission at room temperature, or the capability of tuning the band-gap with the size or the base material. In addition, their solution process nature enables an easy integration on several substrates and photonic structures. As a consequence, these nanoparticles have been extensively proposed to devel…
Silicon Nanocrystals Produced by Nanosecond Laser Ablation in an Organic Liquid
2011
Small (3−5 nm in diameter following HRTEM images) Si nanocrystals were produced in a two-stage process including (1) nanosecond laser ablation of a Si target in an organic liquid (chloroform) that results in formation of big composite polycrystalline particles (about 20−100 nm average diameter) and (2) ultrasonic post-treatment of Si nanoparticles in the presence of HF. The post-treatment is responsible for disintegration of the composite Si particles, release of small individual nanocrystals, and reduction of their size due to HF-induced etching of Si oxide. The downshift and broadening of the ∼520 cm−1 Raman phonon band of the small Si nanocrystals with respect to the bulk Si Raman band i…
Strong etching formulation (time and rate) for PADC with deep depth bulk etch rate study
2021
Abstract Aqueous NaOH with ethanol (strong) etchant is widely used. It shortens etching time effectively compared to normal etching conditions (6.25N NaOH at 70 °C). Two equations have been proposed to calculate the etching time with NaOH molarity and ethanol volume. Another two empirical equations were introduced for estimating the bulk etch rates of PADC etched in strong etchant. Up to now, there were no such equations available in the literature that can predict etching time and V b of PADC with etchant molarity and ethanol volumes. The proposed equations were compared to fundamental V b models stemming from literature. Fast etching enables the follow-up of bulk etch rate variation versu…
Arrays of normal metal tunnel junctions in weak Coulomb blockade regime
1995
Universal features of I–V characteristics of one‐dimensional arrays of normal metal tunnel junctions have been tested against inhomogenities in the junction parameters, number of junctions in the array, and magnetic field. We find that the differential conductance versus bias voltage obeys the analytic form to within 1% if the fabrication errors are smaller than 10% in junction areas, and if the array has more than ten junctions. Furthermore, the universal relation is insensitive to magnetic field at least up to 8 T.
The constellation-X focal plane microcalorimeter array: An NTD-germanium solution
2002
The hallmarks of Neutron Transmutation Doped (NTD) germanium cryogenic thermistors include high reliability, reproducibility, and long term stability of bulk carrier transport properties. Using micro-machined NTD Ge thermistors with integral “flying” leads, we can now fabricate two-dimensional arrays that are built up from a series of stacked linear arrays. We believe that this modular approach of building, assembling, and perhaps replacing individual modules of detectors is essential to the successful fabrication and testing of large multi-element spectrometers. Details of construction are presented.
Multipactor Analysis in Circular Waveguides
2009
[EN] This paper mainly focuses on demonstrating that a multipactor discharge can occur within a circular waveguide operating under the fundamental TE11 circular mode. Circular waveguides are widely used in the fabrication of many passive components, in order to implement resonant cavities as well as irises to connect adjacent guides for both application domains, particle accelerators and satellite subsystems applications. Thus, we present the first study of the multipactor effect in a circular waveguide, demonstrating its existence and providing a susceptibility chart for such a structure, which will be of great interest for the better understanding of multipactor physical phenomena.