Search results for "Stability"
showing 10 items of 3085 documents
Proteins in amorphous saccharide matrices: Structural and dynamical insights on bioprotection
2013
Bioprotection by sugars, and in particular trehalose peculiarity, is a relevant topic due to the implications in several fields. The underlying mechanisms are not yet clearly elucidated, and remain the focus of current investigations. Here we revisit data obtained at our lab on binary sugar/water and ternary protein/sugar/water systems, in wide ranges of water content and temperature, in the light of the current literature. The data here discussed come from complementary techniques (Infrared Spectroscopy, Molecular Dynamics simulations, Small Angle X-ray Scattering and Calorimetry), which provided a consistent description of the bioprotection by sugars from the atomistic to the macroscopic …
Near Room-Temperature Memory Devices Based on Hybrid Spin-Crossover@SiO2Nanoparticles Coupled to Single-Layer Graphene Nanoelectrodes
2016
The charge transport properties of SCO [Fe(Htrz)2 (trz)](BF4 ) NPs covered with a silica shell placed in between single-layer graphene electrodes are reported. A reproducible thermal hysteresis loop in the conductance above room-temperature is evidenced. This bistability combined with the versatility of graphene represents a promising scenario for a variety of technological applications but also for future sophisticated fundamental studies.
Two-terminal nanoelectromechanical devices based on germanium nanowires.
2009
A two-terminal bistable device, having both ON and OFF regimes, has been demonstrated with Ge nanowires using an in situ TEM-STM technique. The function of the device is based on delicately balancing electrostatic, elastic, and adhesion forces between the nanowires and the contacts, which can be controlled by the applied voltage. The operation and failure conditions of the bistable device were investigated, i.e. the influence of nanowire diameter, the surface oxide layer on the nanowires and the current density. During ON/OFF cycles the Ge nanowires were observed to be more stable than carbon nanotubes, working at similar conditions, due to the higher mechanical stability of the nanowires. …
Pulsed-laser switching in the bistability domain of a cooperative spin crossover compound: a critical study through calorimetry
2015
The photoswitching from the low spin (LS) to high spin (HS) state and the reverse process in the bistability domain of spin crossover (SCO) compounds is a promising function to be used in molecular electronic devices, and evidenced mainly through spectroscopy. The phenomenon, and in particular its mechanism, is however still under debate since some controversial experimental results have been reported. Here we present a calorimetric experimental study of the photoswitching of the [Fe(pyrazine)Pt(CN)4] SCO material by a nanosecond-pulsed green laser. Our results confirm that the single laser pulse of varying energies results in significant LS to HS transformations and show that calorimetry p…
Electrical conductivity and magnetic bistability in metal–organic frameworks and coordination polymers: charge transport and spin crossover at the na…
2020
Materials scientists are currently shifting from purely inorganic, organic and silicon-based materials towards hybrid organic–inorganic materials to develop increasingly complex and powerful electronic devices. In this context, it is undeniable that conductive metal–organic frameworks (MOFs) and bistable coordination polymers (CPs) are carving a niche for themselves in the electronics world. The tunability and processability of these materials alongside the combination of electrical conductivity with porosity or spin transition offers unprecedented technological opportunities for their integration into functional devices. This review aims to summarise the chemical strategies tha…
Temperature dependence of refractive index and absorption coefficient of GaSe at 633 nm
1995
Abstract Measurements of the ordinary refractive index and the absorption coefficient ( E /t] to c axis ) of gallium selenide at 633 nm, in the temperature range [20,100] °C, are reported. Useful analytical approximations obtained after a least squares fitting process are provided, as well. These results are basic for any theoretical model of nonlinear and bistable optical devices based on GaSe.
Two-terminal nanoelectromechanical bistable switches based on molybdenum–sulfur–iodine molecular wire bundles
2010
We demonstrate the application of Mo(6)S(3)I(6) molecular wire bundles for electrically controllable two-terminal on-off switches. We investigate how changes in the contact electrode material and geometry influence the device characteristics, hysteretic switching behavior and device stability. We also determine the device operating parameters, particularly the Young's moduli (40-270 GPa), operating current densities (3.2 x 10(5)-7 x 10(6) A m(-2)) and force constants. Although qualitatively, the properties of Mo(6)S(3)I(6) nanowires in nanoelectromechanical (NEM) switches are similar to those of carbon nanotubes (CNTs), their lower friction coefficient, higher mechanical stability and highe…
Optical flip-flop memory and routing operation based on polarization bistability in optical fiber
2014
A polarization bistability and hysteresis cycle phenomenon is demonstrated in optical fibers thanks to a counter-propagating four-wave mixing interaction. Based on this process, we successfully report the proof-of-principle of an optical flip-flop memory and a 10-Gbit/s routing operation.
Biomechanical evaluation of oversized drilling technique on primary implant stability measured by insertion torque and resonance frequency analysis
2015
Background This study evaluated the influence of implant site preparation depth on primary stability measured by insertion torque and resonance frequency analysis (RFA). Material and Methods Thirty-two implant sites were prepared in eight veal rib blocks. Sixteen sites were prepared using the conventional drilling sequence recommended by the manufacturer to a working depth of 10mm. The remaining 16 sites were prepared using an oversize drilling technique (overpreparation) to a working depth of 12mm. Bone density was determined using cone beam computerized tomography (CBCT). The implants were placed and primary stability was measured by two methods: insertion torque (Ncm), and RFA (implant s…
Influence of mechanical activation on the physical stability of salbutamol sulphate.
2003
Abstract In order to obtain the optimal particle size distribution for pharmaceutical powders in dry powder inhalers the particles have to be micronised. In most cases the process of micronisation is connected with a high input of energy which induces disorder and defects on the surface of the drug particles and as a result changes in the crystallinity. Consequently, changes in the physical stability of the powders may occur. To investigate changes on the physical stability of the powder, different analytical methods are used in the present investigation: laser diffraction, Differential Scanning Calorimetry (DSC), isothermal microcalorimetry and DVS-method. Air-jet-milling is one of the mos…