Search results for "Static"
showing 10 items of 1528 documents
Atomic Force Microscopy and Spectroscopy
2021
Atomic force microscopy (AFM) is probably the most celebrated technique falling into the family of experimental methods known as scanning probe microscopy. AFM is primarily designed to obtain the morphology of the surface of a solid material by using the force of interaction between an inert probe and the sample. The AFM microscope can generally be operated in many ways for morphology investigations, but they can be roughly classified into two main groups: static- and dynamic-deflection modes. Since atomic force microscopy makes use of tip-surface interaction to reconstruct the surface morphology of materials, it is of fundamental importance to fully understand the nature and properties of …
Testing the concentric-disk tension infiltrometer for field measurement of soil hydraulic conductivity
2010
Abstract The concentric-disk tension infiltrometer (CDTI) may be used to simultaneously measure the confined ( K c ) and the unconfined ( K u ) soil hydraulic conductivity, but it has received little testing. Comparison between K c and K u can be affected by the calculation approach applied to analyze unconfined steady-state infiltration rates. The objectives of this investigation were to: i) establish the effect of the calculation approach on the estimates of K u ; and ii) compare the K c and K u values measured by the CDTI. A clay soil, a structureless sandy loam soil, and a sandy loam soil with a relatively high gravel content were sampled using a disk of radius equal to 107.5 mm, compri…
Pressure effect investigations on spin-crossover coordination compounds
2018
International audience; The piezochromic properties of spin-crossover complexes have been recognized for a long time, with increasing pressure favouring the low spin state due to its smaller volume and therefore shifting the spin equilibrium towards higher temperatures and accelerating the relaxation at a given temperature. However, the interpretation and quantification of pressure-induced changes have been several times compromised by the relatively poor and incomplete spectral and structural information provided by the detection methods or due to the experimental difficulties related to the need for hydrostatic conditions at low temperatures. The present review is therefore primarily focu…
Conformational Changes and Charge Transfer in Biomolecules Resolved Using Dynamic Enhanced Raman Correlation Spectroscopy
2019
International audience; In this contribution, we report that conforma-tional changes of molecules that are often buried in a wide-distributed Gaussian distribution can be discerned by analyzing the dynamics of specific Raman lines. We investigate the pertinence of the auto-and cross-correlation functions applied to the dynamics of three Raman lines of an amino acid, the tryptophan. The cross-correlation between intensity and the Raman band is an indicator of the charge transfer during the diffusion limited reaction of tryptophan and the gold surface. The Pećlet number Pe can provide a valuable indicator of the convective and/or diffusive features of each Raman band. Adsorption induced confo…
Salt-fog spray aging of jute-basalt reinforced hybrid structures. Flexural and low velocity impact response
2017
Abstract In this work, a study on the aging resistance of jute and jute-basalt interply hybrid laminates exposed to salt-fog is presented with the aim to investigate the possibility to enhance the durability of natural fiber reinforced composites for marine application by a ply-substitution approach. In particular, jute and basalt/jute reinforced composite plates were manufactured by vacuum assisted resin infusion in two different staking sequences (i.e., intercalated and sandwich-like basalt-jute) and aged under salt fog conditions. The effects of the accelerated aging at increasing times on the mechanical response of laminates were assessed in both quasi static (three point bending) and d…
Investigation and modeling of the anomalous yield point phenomenon in pure tantalum
2014
International audience; The monotonic and cyclic behavior of commercially pure tantalum has been investigated at room temperature, in order to capture and understand the occurrence of the anomalous yield point phenomenon. Interrupted tests have been performed, with strain reversals (tensile or compressive loading) after an aging period. The stress drop is attributed to the interactions between dislocations and solute atoms (oxygen) and its macroscopic occurrence is not systematically observed. InfraRed Thermography (IRT) measurements supported by Scanning Electron Microscopy (SEM) pictures of the polished gauge length of a specimen during an interrupted tensile test reveal the nucleation an…
Microstructure-oxidation resistance relationship in Ti3AlC2 MAX phase
2020
International audience; Spark Plasma Sintering and Hot Isostatic Pressing were used to synthesize coarse-grained and fine-grained Ti3AlC2 specimens. Moreover, Spark Plasma Sintering processing parameters were modified in order to vary the TiC, Al2O3 and TixAly impurity and the porosity contents in the fine-grained samples. The influence of the Ti3AlC2 microstructure on the oxidation resistance was assesed. It is demonstrated that the grain size can drastically modify the oxidation resistance. The higher density of grain boundaries, in fine-grained specimens, increases the number of Al diffusion paths and leads to the formation of a protective alumina scale. In coarse-grained sample, Al diff…
Static and dynamic mechanical properties of Arundo Donax fillers-epoxy composites
2014
Abstract Aim of this work is to investigate the feasibility of using a natural and inexpensive filler obtained by grinding the culms of Arundo Donax as reinforcement of epoxy resins. The effect of the content and size of Arundo Donax fillers on static and dynamic mechanical properties was evaluated showing that the composites exhibit higher tensile moduli, comparable flexural moduli and lower strength properties in comparison to the neat resin. Moreover, changes in the storage and the loss moduli only above the glass transition temperature (i.e. in the rubbery region) were found while neither significant shifts of tan δ peaks to higher temperatures nor reductions in the peak height of the c…
Non-contact ultrasonic inspection of skin/core bond in honeycomb with lamb waves
2003
The assessment of skin/core bond in honeycomb samples was carried out by a bistatic ultrasonic non-contact system. Lamb waves were generated by a Nd:YAG pulsed laser and detected by an air-coupled capacitance transducer located in pitch-catch configuration. Periodically spaced line sources, generated on the sample surface using a four element lenticular array, allowed generation of narrow-band directional Lamb waves. Changes in amplitude of the transmitted signal permitted detection of skin/core disbonds.
Second-harmonic generation in Langmuir–Blodgett monolayers of stilbazium salt and phenylhydrazone dyes
1988
The second-order nonlinear optical susceptibilities χ(2) of several phenylhydrazone and stilbazium salt dyes in Langmuir–Blodgett monolayers have been determined from second-harmonic-generation measurements. Three of the substances demonstrated χ(2) values greater than 10−6 electrostatic units, although two of the three did not absorb light significantly at the second-harmonic wavelength.