Search results for "Absorption"
showing 10 items of 2701 documents
Sublimable chloroquinolinate lanthanoid single-ion magnets deposited on ferromagnetic electrodes
2018
A new family of chloroquinolinate lanthanoid complexes of the formula A+[Ln(5,7Cl2q)4]−, with Ln = Y3+, Tb3+ and Dy3+ and A+ = Na+, NEt4+ and K0.5(NEt4)0.5+, is studied, both in bulk and as thin films. Several members of the family are found to present single-molecule magnetic behavior in bulk. Interestingly, the sodium salts can be sublimed under high vacuum conditions retaining their molecular structures and magnetic properties. These thermally stable compounds have been deposited on different substrates (Al2O3, Au and NiFe). The magnetic properties of these molecular films show the appearance of cusps in the zero-field cooled curves when they are deposited on permalloy (NiFe). This indic…
Effect of Aspect ratio and water contamination on the electric properties of nanostructured insulating materials
2010
Organically-modified nanofiller clays can have significantly different aspect ratios as well as accumulate a relatively large amount of water in the composite bulk due to the contribution of the filler itself and the interaction between filler and polymer matrix. This paper investigates the effect of water absorption in a nanostructured thermoplastic polymer, namely ethylene-vinyl-acetate (EVA), on electrical property modifications considering the contribution of aspect ratio. The change of electrical properties (particularly space charge accumulation, electric strength, bulk conductivity and permittivity/losses) is studied as a function of water content absorbed by nanofillers having diffe…
Dielectric spectroscopy and molecular dynamics of methylene chloride CH2Cl2
1991
Abstract Precise measurements of the complex permittivity of methylene chloride (CH 2 Cl 2 ) at 293 K have been made at frequencies in the range 50–310 GHz. These, when combined with earlier results, have made possible a determination of the complex permittivity over the entire zero to THz frequency region. These results show a distribution of dielectric relaxation times. The value of the Cole-Cole distribution parameter, α, was 0.03 and that of the relaxation time, τ, was 2.07 ps. A comparison of the power absorption, A (ω), spectra of pure methylene chloride with the normalized dilute solution spectra shows that: (a) the integrated absorption intensity of the pure liquid is 20% greater th…
Oxide or carbide nanoparticles synthesized by laser ablation of a bulk Hf target in liquids and their structural, optical, and dielectric properties
2016
International audience; Laser ablation of a bulk Hf target in deionized (DI) water, ethanol, or toluene was carried out for the production of nanoparticles' colloidal solutions. Due to the interaction of the ablation plasma plume species with the species which are produced by the liquid decomposition at the plume-liquid interface, hafnia (HfO2) nanoparticles are synthesized in DI water, hafnium carbide (HfC) nanoparticles in toluene, and a mixture of these in ethanol. The hafnia nanoparticles are in the monoclinic low temperature phase and in the tetragonal and fcc high temperature phases. Their size distribution follows log-normal function with a median diameter in the range of 4.3–5.3 nm.…
Dielectric characterization of biocompatible hydrogels for application to Epidermal RFID devices
2015
Functionalized skin-like membranes are currently under investigation for the design of a new class of Epidermal Electronics devices for sensing and healing applications. The dynamic response of epidermal antennas in presence of absorption and release of fluids is a key-point to design RFID radio-sensors and actuators. This paper addresses the characterization of the dielectric property of PVA-based biocompatible hydrogel membranes in the UHF RFID band by means of a modified ring resonator. Samples having different compositions are measured in the dry state as well as when exposed to a progressive release of body fluids emulating perspirations or wound exudates. It was found that the permitt…
Proton presence and motion in rhenium-oxide films and their application to liquid-crystalline cells
2007
Disordered solid phases, containing appreciable amounts of hydrogen ions, are grown at the surface of rhenium oxide crystals, because of the high reactivity of this compound with ambient moisture. To investigate such phenomena, a comparative study is performed on ground powder and thermally evaporated or sputtered films using x-ray diffraction and micro-Raman spectroscopy. Two types of solid phases were found in the films: HxReO3 distorted perovskite structures, based on corner-sharing ReO6 octahedra as in the bulk crystals, and ordered HReO4 crystalline structures, based on tetrahedral perrhenate ions. The complex impedance measurements on ReO3 films support the hypothesis of mobile hydrog…
A Metal-Based Receptor for Selective Coordination and Fluorescent Sensing of Chloride
2021
A scorpionate Zn2+ complex, constituted by a macrocyclic pyridinophane core attached to a pendant arm containing a fluorescent pyridyl-oxadiazole-phenyl unit (PyPD), has been shown to selectively recognize chloride anions, giving rise to changes in fluorescence emission that are clearly visible under a 365 nm UV lamp. This recognition event has been studied by means of absorption, fluorescence, and NMR spectroscopy, and it involves the intramolecular displacement of the PyPD unit by chloride anions. Moreover, since the chromophore is not removed from the system after the recognition event, the fluorescence can readily be restored by elimination of the bound chloride anion.
Nonlinearities in amoxycillin pharmacokinetics. II. Absorption studies in the rat.
1992
Most factors influencing amoxycillin oral absorption are, even today, unknown. Since many dosage schedules have been shown to lead to incomplete absorption, it would be desirable to find a suitable animal model where these factors could be studied in depth. In this paper, it is shown that, in the rat, plasma level curves obtained after oral doses of 7 and 28 mg kg-1 are poorly fitted using first-order absorption kinetics and that the best fit is obtained through the use of an input equation combining zero and first-order kinetics. In contrast, plasma level curves found after intraduodenal administration of amoxycillin solutions (7 mg kg-1) are well fitted by first-order input kinetics. It w…
Improvement of trospium-specific absorption models for fasted and fed states in humans
2014
The purpose of this study was to mechanistically interpret the oral absorption pattern of trospium in fasted and fed states by means of gastrointestinal simulation technology. A drug absorption model was built on the basis of experimental data. According to the generated model, low permeability across the intestinal epithelium, delayed gastric emptying time and a prolonged residence time in the small intestine are the key factors governing trospium absorption in the fasted state. Furthermore, in silico modelling provided a plausible explanation of the pronounced reduction in the oral bioavailability of trospium when administered with food. The simulation results support the decreased dissol…
ComparativeIn Vitroevaluation of cumulative release of the urinary antiseptics Nalidixic acid, Pipemidic acid, Cinoxacin, and norfloxacin from white …
1994
AbstractThe in vitro diffusion of nalidixic acid (1), pipemidic acid (2), cinoxacin (3), and norfloxacin (4) was studied. The transfer rate constants (kd) from simulated gastro-intestinal juices to simulated plasma, throughout artificial wall lipid membranes, were defined. The kd values suggested that the four drugs are absorbed both in gastric and intestinal environments in similar amounts. To obtain lack of gastric unwanted effects white beeswax microspheres containing 1, 2, 3, and 4 were investigated as a vehicle for the drug intestinal release; they were prepared by the meltable dispersion process using wetting agents. Discrete, reproducible free flowing microspheres were obtained. The …