Loss modeling and thermal measurement in planar inductors-a case study

This paper covers the experimental investigation and theoretical calculation of losses in a planar inductor under load. Finite-element software is used to perform the loss calculations. Thermally controlled experiments are performed for a range of frequencies to validate the corresponding finite-element method loss calculations. The thermal dependence of the loss mechanisms is also considered.     

Qualitative assessment of microstructure and Hertzian indentation failure in biocompatible glass ionomer cements

Discs of biocompatible glass ionomer cements were prepared for Hertzian indentation and subsequent fracture analyses. Specifically, 2 × 10 mm samples for reproducing bottom-initiated radial fracture, complemented by 0.2 × 1 mm samples for optimal resolution with X-ray micro tomography (μCT), maintaining dimensional ratio. The latter allowed for accurate determination of volumetric-porosity of the fully cured material, fracture-branching through three Cartesian axes and incomplete bottom-initiated cracking. Nanocomputed tomography analyses supported the reliability of the μCT results. Complementary 2-dimensional fractographic investigation was carried out by optical and scanning electron microscopies on the larger samples, identifying fracture characteristics. The combined 3-D qualitative assessment of microstructure and fractures, complemented by 2-D methods, provided an increased understanding of the mechanism of mechanical failure in these cements. Specifically, cracks grew to link pores while propagating along glass-matrix interfaces. The methodological development herein is exploitable on related biomaterials and represents a new tool for the rational characterisation, optimisation and design of novel materials for clinical service.     

Theoretical investigation of catalytic HCO3 hydrogenation in aqueous solutions

Density functional theory along with a dielectric continuum solvation model has been applied to identify possible reaction intermediates for the catalytic hydrogenation of HCO₃⁻ anion into HCO₂⁻ that occurs in aqueous solutions in the presence of water-soluble ruthenium complexes. Bicarbonate ion is shown to coordinate to a Ru-dihydride species, which then undergoes a protonation process that yields a CO₂ complex. The CH bond formation is found to take place via CO₂ insertion into a RuH bond and the direct elimination of the formate product is shown to be an energetically favored step, which is assisted by the water medium. We find that water is directly involved in the reaction as a protonating/deprotonating agent and also acts as a coordinating ligand.     

Electrodeposition and dissolution of yttrium-hexacyanoferrate layers

The electrodeposition and dissolution of yttrium-hexacyanoferrate [YHCNFe(II)] were investigated by electrochemical quartz crystal microbalance technique (EQCM). The electrodeposition was carried out by potential cycling or stepping from solutions of Y(NO₃)₃ and K₃[Fe^III(CN)₆] of different concentrations. The ratio of the reactants was also varied. No deposition was found in dilute solutions (c < 10⁻³ mol dm⁻³). The increase of concentrations led to an intense deposition of YHCNFe(II) in the course of reduction of [Fe^III(CN)₆]³⁻. At high concentrations of the reactants a coagulation deposition of YHCNFe(III) at open-circuit has also been detected. During the reduction the first phase is the nucleation which requires saturation or oversaturation in respect to the reacting species near the gold surface. The growth phase is much faster than the formation of nuclei, and its rate depends on the concentration and the concentration ratio of the species. The composition of the deposits has been determined by total reflection X-ray fluorescence (TXRF) spectrometry. From the molar ratio of atomic constituents (K, Y and Fe) of the slightly soluble deposit (solubility: 5 × 10⁻⁵ mol dm⁻³) formed after reduction of Fe(III) a formula K_0.46Y_1.18[Fe^II(CN)₆] can be derived. This value is in good accordance with the molar mass calculated from the results of EQCM experiments which also revealed that the deposit contains ca. 2 mol H₂O/mol YHCNFe(II). The solubility of YHCNFe(III) is substantially higher (s = 2 × 10⁻³ mol dm⁻³), and according to the results of TXRF measurements, its composition is Y[Fe^III(CN)₆]. The reoxidation of YHCNFe(II) takes place in two steps. The first one is a partial oxidation which is accompanied by the desorption of K⁺ ions from the layer. During further oxidation a fast dissolution occurs due to the high solubility of YHCNFe(III).     

First data from the EGLE experiment onboard the ISS

EGLE is a wide frequency band search- coil magnetometer designed and built at the Roma Tre University. It has been installed onboard the ISS by the Italian astronaut Roberto Vittori on April 25, 2005 within the LAZIO- EGLE experiment carried out during the ENEIDE Soyuz mission. The scope of the experiment is to test EGLE in space and to investigate geomagnetic field variations. The main applications of EGLE are the study of electromagnetic environment inside the ISS, the correlation of magnetic field data with particle fluxes detected by LAZIO particle detector, and the monitoring of ionospheric perturbations possibly caused by Earth seismic activity. Since continuous electromagnetic field measurements on board the ISS are important for diverse space applications, a magnetometer with a suitable design is requested. Appropriate solutions for these applications, which have been adopted by EGLE, are in particular the use of 1- Wire technology and the possibility to detect by means of a search- coil magnetometer a large portion of the ULF frequency band, usually measured by flux- gate probes. To investigate the topside ionosphere electromagnetic environment and stability of Van Allen radiation belts in relation with seismic and anthropogenic electromagnetic emissions, a specific satellite mission (the ESPERIA project) has been designed for the Italian Space Agency (ASI), and up to now a few instruments of its payload have been built and tested in space. One of them is exactly the EGLE search- coil magnetometer. The first magnetic observations performed by this instrument reveal to be promising and demand for a further and deeper analysis based on a longer time series of data.     

Estimation of the Thermodynamic Limit of Overheating for Bulk Water from Interfacial Properties

The limit of overheating or expanding is an important property of liquids, which is relevant for the design and safety assessment of processes involving pressurized liquids. In this work, the thermodynamic stability limit—the so-called spinodal—of water is calculated by molecular dynamics computer simulation, using the molecular potential model of Baranyai and Kiss. The spinodal pressure is obtained from the maximal tangential pressure within a liquid–vapor interface layer. The results are compared to predictions of various equations of state. Based on these comparisons, a set of equations of state is identified which gives reliable results in the metastable (overheated or expanded) liquid region of water down to $-55$  MPa.     

Stability test of novel combined formulated dry powder inhalation system containing antibiotic: physical characterization and in vitro–in silico lung deposition results

Objective: The aim was to study the stability of dry powder inhaler (DPI) formulations containing antibiotic with different preparation ways – carrier-based, carrier-free, and novel combined formulation – and thereby to compare their physicochemical and in vitro–in silico aerodynamical properties before and after storage. Presenting a novel combined technology in the field of DPI formulation including the carrier-based and carrier-free methods, it is the most important reason to introduce this stable formulation for the further development of DPIs.

Methods: The structure, the residual solvent content, the interparticle interactions, the particle size distribution and the morphology of the samples were studied. The aerodynamic values were determined based on the cascade impactor in vitro lung model. We tested the in silico behavior of the novel combined formulated samples before and during storage.

Results: The physical measurements showed that the novel combined formulated sample was the most favorable. It was found that thanks to the formulation technique and the use of magnesium stearate (MgSt) has a beneficial effect on the stability compared with the carrier-based formulation without MgSt and carrier-free formulations. The results of in vitro and in silico lung models were consistent with the physical results, so the highest deposition was found for the novel combined formulated sample during the storage.

Conclusions: It can be established that after the storage a novel combined formulated DPI contained amorphous drug to have around 2.5?μm mass median aerodynamic diameter and nearly 50% fine particle fraction predicted high lung deposition in silico also.     

Analysis of Amadori compounds by high-performance cation exchange chromatography coupled to tandem mass spectrometry

High-performance cation exchange chromatography coupled to tandem mass spectrometry or electrochemical detection was found to be an efficient tool for analyzing Amadori compounds derived from hexose and pentose sugars. The method allows rapid separation and identification of Amadori compounds, while benefiting from the well-known advantages of mass spectrometry, such as specificity and sensitivity. Glucose- and xylose-derived Amadori compounds of several amino acids, such as glycine, alanine, valine, leucine/isoleucine, methionine, proline, phenylalanine, and glutamic acid, were separated or discriminated using this new method. The method is suitable for the analysis of both model reaction mixtures and food products. Fructosylglutamate was found to be the major Amadori compound in dried tomatoes (approximately 1.5 g/100 g) and fructosylproline in dried apricots (approximately 0.2 g/100 g). Reaction of xylose and glycine at 90 degrees C (pH 6) for 2 h showed rapid formation of xylulosylglycine (approximately 12 mol %, 15 min) followed by slow decrease over time. Analysis of pentose-derived Amadori compounds is shown for the first time, which represents a major breakthrough in studying occurrence, formation, and decomposition of these labile Maillard intermediates.