Search results for "HYSTERESIS"
showing 10 items of 245 documents
Influence of Corneal Opacity on Intraocular Pressure Assessment in Patients with Lysosomal Storage Diseases
2017
Aims To investigate an influence of mucopolysaccharidosis (MPS)- and Morbus Fabry-associated corneal opacities on intraocular pressure (IOP) measurements and to evaluate the concordance of the different tonometry methods. Methods 25 MPS patients with or without corneal clouding, 25 Fabry patients with cornea verticillata ≥ grade 2 and 25 healthy age matched controls were prospectively included into this study. Outcome measures: Goldmann applanation tonometry (GAT); palpatory assessment of IOP; Goldmann-correlated intraocular pressure (IOPg), corneal-compensated intraocular pressure (IOPcc), corneal resistance factor (CRF) and corneal hysteresis (CH) assessed by Ocular Response Analyzer (ORA…
Evolutionary Hysteresis and Ratchets in the Evolution of Periodical Cicadas
2019
It has been previously hypothesized that the perfectly synchronized mass emergence of periodical cicadas (Magicicada spp.) evolved as a result of a switch from size-based to age-based emergence. In the former case, cicada nymphs emerge immediately (at the first opportunity) on reaching maturity, whereas in the latter case, nymphs wait in order to emerge at a specific age. Here we use an individual-based model to simulate the cicada life cycle and to study the evolution of periodicity. We find that if age-based emergence evolves in a constant abiotic environment, it typically results in a population that is protoperiodic, and synchronous emergence of the whole population is not achieved. How…
Anterior Segment Biometry and Their Correlation with Corneal Biomechanics in Caucasian Children.
2018
Purpose: To assess the relationship between the corneal biomechanical parameters and the anterior segment parameters in Caucasian children. Methods: This study included 293 eyes from 293 healthy children aged between 6 and 17 years. Corneal hysteresis (CH) and corneal resistance factor (CRF) were evaluated with the Ocular Response Analyzer, axial length (AL) with IOLMaster and the anterior segment with Pentacam. Anterior segment parameters obtained were the following: central corneal thickness (CCT), corneal volume (CV), anterior chamber depth (ACD), anterior chamber volume (ACV) and mean anterior and posterior keratometry. Two multiple linear regression models were constructed to assess th…
Hysteresis in the temperature dependence of the IR bending vibration of deeply cooled confined water.
2019
Using Fourier Transform Infrared (FTIR) spectroscopy, we investigate the temperature dependence of the bending vibrations of water confined in the pores of a silica hydrogel in the temperature interval of 270-180 K. We also investigate the presence of thermal hysteresis by cooling and reheating temperature scans. The results clearly show the presence, at about 230 K, of a crossover in the temperature dependence of the IR spectra; moreover, the presence of hysteresis is clearly demonstrated. By comparing FTIR data with neutron diffraction data and previous calorimetric data on the same samples, we conclude that the crossover and the hysteretical behavior do not involve a water glass transiti…
Discrimination between two memory channels by molecular alloying in a doubly bistable spin crossover material
2019
[EN] A multistable spin crossover (SCO) molecular alloy system [Fe1-xMx(nBu-im)(3)(tren)](P1-yAsyF6)(2) (M = Zn-II, Ni-II; (nBu-im)(3)(tren) = tris(n-butyl-imidazol(2-ethylamino))amine) has been synthesized and characterized. By controlling the composition of this isomorphous series, two cooperative thermally induced SCO events featuring distinct critical temperatures (T-c) and hysteresis widths (Delta T-c, memory) can be selected at will. The pristine derivative 100As (x = 0, y = 1) displays a strong cooperative two-step SCO and two reversible structural phase transitions (PTs). The low temperature PTLT and the SCO occur synchronously involving conformational changes of the ligand's n-buty…
Thermo- and photo-modulation of exciplex fluorescence in a 3D spin crossover Hofmann-type coordination polymer
2018
[EN] The search for bifunctional materials showing synergies between spin crossover (SCO) and luminescence has attracted substantial interest since they could be promising platforms for new switching electronic and optical technologies. In this context, we present the first three-dimensional Fe-II Hofmann-type coordination polymer exhibiting SCO properties and luminescence. The complex {Fe-II(bpben)[Au(CN)(2)]}@pyr (bpben = 1,4-bis(4-pyridyl)benzene) functionalized with pyrene (pyr) guests undergoes a cooperative multi-step SCO, which has been investigated by single crystal X-ray diffraction, single crystal UV-Vis absorption spectroscopy, and magnetic and calorimetric measurements. The resu…
Permeability measurements in cobalt ferrite and carbonyl iron powders and suspensions
2002
Abstract Magnetic permeability data of cobalt ferrite and carbonyl iron suspensions are discussed. Using an induction method, the relative differential permeability, μr,dif, was measured as a function of the internal magnetic field for different volume fractions of the solid phase. In the case of cobalt ferrite suspensions, the μr,dif−H curve was obtained for a first increasing ramp of magnetic field (data series “1”), a decreasing ramp (data series “2”), and the second increasing one (data series “3”). Series “1” showed a maximum in the μr,dif−H trend that did not appear in series “2” and “3”. Furthermore, the data in series “2” and “3” are always below those in series “1”. The latter beha…
Humidity-Induced Grain Boundaries in MAPbI3 Perovskite Films
2016
Methylammonium lead halide perovskites (MAPbI3) are very sensitive to humid environments. We performed in situ scanning force microscopy and in situ X-ray diffraction measurements on MAPbI3 films to track changes in the film morphology and crystal structure upon repeated exposure to a high relative humidity environment (80%). We found that the appearance of monohydrate (MAPbI3·H2O) Bragg reflections coincided with the appearance of additional grain boundaries. Prolonging the exposure time to humidity induced more grain boundaries and steps in the MAPbI3 films, and the peak intensities of the monohydrate MAPbI3·H2O increased. The monohydrate was not stable under dry atmosphere and could be r…
Strain-controlled domain wall injection into nanowires for sensor applications
2021
We investigate experimentally the effects of externally applied strain on the injection of 180$^\circ$ domain walls (DW) from a nucleation pad into magnetic nanowires, as typically used for DW-based sensors. In our study the strain, generated by substrate bending, induces in the material a uniaxial anisotropy due to magnetoelastic coupling. To compare the strain effects, $Co_{40}Fe_{40}B_{20}$, $Ni$ and $Ni_{82}Fe_{18}$ samples with in-plane magnetization and different magnetoelastic coupling are deposited. In these samples, we measure the magnetic field required for the injection of a DW, by imaging differential contrast in a magneto-optical Kerr microscope. We find that strain increases t…
Characterization and magnetic properties of nanoparticles based on FePt solid solution with an oxide shell
2015
Abstract We present the results of magnetic properties investigations of ferromagnetic nanoparticles which ensembled with ferromagnetic shell. The aim of this work is to study the connection of structure–phase composition and thermal treatment with the magnetic properties, partially, with the coercive force and the exchange bias field in a two-dimension spin system of core–shell type. It is found that the exchange bias field increases with the growth of the oxide shell thickness. This is realized by annealing in a dosed oxygen flow. The decrease of the coercive force with the increase of annealing temperature is connected with the concentration effect (the concentration of ferromagnetic par…