Search results for "Surfaces"
showing 10 items of 2837 documents
H−ZSM-5 Modified Zeolite: Quantum Chemical Models of Acidic Sites
2007
A ZSM-5 fragment, containing 52 tetrahedral moieties, each of them formed by one silicon or one aluminum atom surrounded by four oxygen atoms, was employed to model (52T systems) by quantum chemical calculations (i) the influence of the positions of the acidic sites on the energetics of 22 aluminum monosubstituted and bisubstituted 52T acidic zeolite (H-ZSM-5) systems and (ii) the local adsorption properties and acidic strength of the corresponding -OH sites. The energetics and the structural properties of simpler acid H-ZSM-5 systems containing only five Tetrahedral moieties (5T systems) were also modeled for comparison. B3LYP/6-31G(d,p) partial geometry optimization routines were performe…
Localization of n-alcohols and structural effects in aqueous solutions of sodium dodecyl sulfate
1997
Small-angle neutron Mattering measurements OD sodium dodecyl sulfate aqueous solutions have been performed in the presence of n-alcohols, from methanol to octanol, at different alcohol concentrations. By modeling the experimental intensities, it was possible to obtain structural information and to derive simultaneously the distribution of the alcohols between the aqueous and the micellar phases. It was found that short chain alcohols tend to remain in the aqueous phase and, by altering the solvent properties, induce a decrease in the aggregation number of sodium dodecyl sulfate micelles. On the other hand, alcohols with longer hydrocarbon chains were found to be present in both phases thoug…
Mechanical and electroconductive properties of spatially distributed double stranded DNA arrays on Au (111)
2008
Abstract Conductive AFM was used to investigate electroconductivity through 10 nm long double stranded DNA molecules in mixed monolayers of thioalkylated-DNA and mercaptohexanol (MCH) on Au (111) surface. The distribution of DNA molecules on the surface was analyzed by tapping mode AFM. Measurements performed in lift mode confirmed that the DNA molecules protrude from the surface rather than lie horizontally adsorbed on the interface. The optimal conductivity measurement time, which is shorter than the mechanical relaxation time of oligonucleotide duplexes, was determined. It was concluded that oligonucleotide duplexes have a resistance of the order of ~ 2 Ω ⁎ m at 1 V.
Pulsed X‐Ray Radiation Responses of Solarization‐Resistant Optical Fibers
2018
International audience; The transient radiation‐induced attenuation (RIA) of two different versions of pure‐silica‐core (PSC) multimode optical fibers (so‐called “solarization‐resistant” fibers) exposed to nanosecond 1 MeV X‐ray pulses are investigated. On‐line RIA spectra measurements at both room temperature (RT) and liquid nitrogen temperatures (LNT) in the range 1–3.5 eV are performed. Following the RIA kinetics, the properties of the metastable defects that are bleached just after the pulse are discussed. The spectral decomposition of the RIA is performed using known Gaussian bands associated to point defects absorbing in this spectral range. For both fiber types, the generation and th…
Performance Analysis of a Prototype High‐Concentration Photovoltaic System Coupled to Silica Optical Fibers
2021
High-concentration photovoltaic (HCPV) systems are one of the most promising technologies for the generation of renewable energy with high-conversion efficiency. Their development is still at an early stage, but the possibility of integrating high-concentration systems into buildings offers new opportunities to achieve the net-zero-energy building goal. Herein, the optical and energetic performance of a hybrid daylighting−HCPV prototype based on pure- or doped-silica optical fibers (OFs) to guide 2000× concentrated sunlight inside the buildings is evaluated. There, the light can either be used to illuminate interior spaces or projected on solar cells to generate electricity. The system equi…
Surface modifications induced by pulsed-laser texturing—Influence of laser impact on the surface properties
2014
Abstract Laser cleaning technology provides a safe, environmentally friendly and very cost effective way to improve cleaning and surface preparation of metallic materials. Compared with efficient cleaning processes, it can avoid the disadvantages of ductile materials prepared by conventional technologies (cracks induced by sand-blasting for example) and treat only some selected areas (due to the optical fibers). By this way, laser technology could have several advantages and expand the range of thermal spraying. Moreover, new generations of lasers (fiber laser, disc laser) allow the development of new methods. Besides a significant bulk reduction, no maintenance, low operating cost, laser f…
A frequency-output fiber optic voltage sensor with temperature compensation for power systems
2003
Abstract We present a frequency-output fiber optic voltage sensor for power systems with temperature compensated response. The sensor employs PZT-type ceramic tubes, which are interrogated by a length of single-mode fiber coiled onto the tubes and a Mach–Zehnder interferometer. The combination of piezoelectric tubes with properties exhibiting opposite behavior to temperature changes is successfully exploited to passively compensate the temperature sensitivity of the sensor. The prototype reported here exhibits a resolution of 13 mV rms and the deviations of the sensor’s response due to temperature changes are within 1% over the temperature range between −30 and 70 °C. The device presented h…
(o-Phenyleno)naphthalene diimides: a pink fluorescent chromophore
2017
(o-Phenyleno)naphthalene dianhydride 7 was synthesized by a six-step reaction. Imidizations of 7 led to various diimides 8. Their optical and electrochemical properties hold promise for organic electronics.
Electrochemical fabrication of metal/oxide/conducting polymer junction
2011
After discovery of conducting polymers and the possibility to modify their electrical properties from insulating to metallic like behavior by doping and a careful choice of the processing conditions, a large amount of research effort has been devoted to the theoretical understanding of their solid state properties as well as to exploit the possible application of conducting polymers in many technological fields including large area organic electronics, polymer photovoltaic cell, and sensors. 1-4 Organic thin film transistors appear very promising devices for the development of low cost, flexible, and disposable plastic electronics. In order to reduce the operating voltage it has been sugges…
High Tolerance of Double-Decker Phthalocyanine toward Molecular Oxygen
2018
Because organic electronics suffer from degradation-inducing oxidation processes, oxygen-tolerant organic molecules could solve this issue and be integrated to improve the stability of devices during operation. In this work, we investigate how lutetium double-decker phthalocyanine (LuPc2) reacts toward molecular oxygen and we report microscopic details of its interaction with LuPc2 film by combining X-ray photoemission spectroscopy, near-edge X-ray absorption fine structure spectroscopy, and density functional theory. Surprisingly, LuPc2 molecules are found to weakly physisorb below 120 K and appear rather inert to molecular oxygen at more elevated temperatures. We are able to draw a micros…