Search results for "powder"
showing 10 items of 437 documents
Spectroscopic ellipsometry applied to phase transitions in solids: possibilities and limitations
2009
The possibilities of in situ spectroscopic ellipsometry applied to phase transitions investigation in oxide thin films and crystals are examined in this work, along with the use of various parameters calculated from ellipsometric data (band gap energy Eg, refractive index n and surface roughness) together with the directly measured main ellipsometric angles psi and Delta, for the detection of phase transitions. The efficiency of spectroscopic ellipsometry on "surface" phase transition and its sensitivity to surface defects are also demonstrated.
Crystallographic changes and thermal properties of lanthanum?strontium ferromanganites between RT and 700 �C
2005
Abstract X-ray powder diffraction was used to determine the crystallographic changes between room temperature (RT) and 700 °C of the (La 0.8 Sr 0.2 )(Mn 1− y Fe y )O 3± δ perovskites with y =0.2, 0.5, 0.8, 1 which can be considered as possible cathode materials for the ITSOFCs. For y =0.2, the rhombohedral symmetry was preserved in the whole temperature range. For y =1, a transition from orthorhombic to rhombohedral symmetry occurred at 290 °C. The compounds with y =0.5 and 0.8 were found to be diphasic at RT by combination of both rhombohedral and orthorhombic symmetries. They became only rhombohedral at 80 and 160 °C, respectively. This reversible transition is discussed in terms of iron …
Exploring the high-pressure behavior of the three known polymorphs of BiPO4: Discovery of a new polymorph
2015
We have studied the structural behavior of bismuth phosphate under compression. We performed x-ray powder diffraction measurements up to 31.5 GPa and ab initio calculations. Experiments were carried out on different polymorphs: trigonal (phase I) and monoclinic (phases II and III). Phases I and III, at low pressure (P < 0.2-0.8 GPa), transform into phase II, which has a monazite-type structure. At room temperature, this polymorph is stable up to 31.5 GPa. Calculations support these findings and predict the occurrence of an additional transition from the monoclinic monazite-type to a tetragonal scheelite-type structure (phase IV). This transition was experimentally found after the simultaneo…
Photoluminescence and photocatalytic activity of zinc tungstate powders
2011
Abstract ZnWO4 powders with grain size in range 20 nm–10 µm have been synthesized by a simple combustion method and subsequent calcinations. The photocatalytic activities of powders were tested by degradation of methylene blue solution under UV light. The luminescence spectra and luminescence decay kinetics were studied and luminescence decay time dependence on average powder-grain size was obtained. The correlation between self-trapped exciton luminescence decay time and photocatalytic activity of ZnWO4 powders was shown. A model explaining the excitonic luminescence decay time correlation with photocatalytic activity was proposed.
Synthesis and processing of nanocrystalline tungsten carbide: Towards cemented carbides with optimal mechanical properties
2011
Abstract Nanocrystalline tungsten carbide has been obtained by reduction/carburization at low temperature from precursors obtained by freeze-drying of aqueous solutions. Nanocrystalline WC powders with a adequate content of carbon were mixed with submicrometric Cobalt powder (12 wt.%), obtained by same synthesis method, and sintered in vacuum furnace. The cemented carbides fabricated from experimental powders were compared with both commercial ultrafine and nanocrystalline WC-12Co mixtures consolidated by the same route. The synthesised powders were characterized by X-ray powder diffraction, elemental analysis and scanning and high resolution transmission electron microscopy. On the other h…
Inhalable polymeric microparticles as pharmaceutical porous powder for drug administration
2022
In this work, the production of inhalable polymeric microparticles with modulable porosity is described. The starting polymeric material was the PHEA-g-RhB-g-PLA graft copolymer, which was suitably processed by spray drying (SD). Thanks to the addition of AB (weight percentage equal to 10 and 20 % with respect to the polymer) in the liquid feed, three biocompatible matrices were obtained with an increasing porosity in terms of pore volume (from 0.015 to 0.024 cc/g) and pore average diameter (from 1.942 to 3.060 nm), a decreasing tapped density values (from 0.75 to 0.50), and favorable aerosolization characteristics. These differences were high-lighted also by a significant increase in the r…
A dose-ranging study of indacaterol in obstructive airways disease, with a tiotropium comparison.
2008
This dose-ranging study assessed the bronchodilator efficacy and tolerability of indacaterol, a novel once-daily inhaled beta2-agonist, in subjects clinically diagnosed with COPD. Comparative data with tiotropium were collected. In the double-blind, core period of the study, 635 subjects with COPD (prebronchodilator FEV(1)40% of predicted and > or =1.0L; FEV1/FVC <70%) were randomized to receive indacaterol 50, 100, 200 or 400microg or placebo via multi-dose dry powder inhaler, or indacaterol 400microg via single-dose dry powder inhaler, once daily for 7 days. After completing double-blind treatment and washout, a subset of subjects from each treatment group entered an open-label extension …
Fluticasone/formoterol combination therapy versus budesonide/formoterol for the treatment of asthma: a randomized, controlled, non-inferiority trial …
2012
The inhaled corticosteroid fluticasone propionate (fluticasone) and the long-acting β₂ agonist formoterol fumarate (formoterol) have been combined in a single aerosol inhaler fluticasone/formoterol (flutiform(®)). This study compared the efficacy and safety of fluticasone/formoterol with the combination product budesonide/formoterol (Symbicort(®) Turbohaler(®)).A randomized, double-blind, double-dummy, multicenter, Phase 3 study comprising a 7- (± 3) day screening, 2-4-week run-in, and 12-week treatment periods. Patients aged ≥ 12 years with moderate to severe persistent asthma for ≥ 6 months before screening and forced expiratory volume in one second (FEV₁) 50-80% predicted and ≥ 15% rever…
The inhalation manager: a new computer-based device to assess inhalation technique and drug delivery to the patient.
2003
The rational choice of an inhalation device is a cornerstone in the effective management of asthma and COPD. In this publication, we describe the development of a new system, the Inhalation Manager, which, for the first time, offers the possibility to assess the entire inhalation maneuver of patients using original devices under everyday conditions. So far the Inhalation Manager allows the measurement of inspiratory maneuvers of patients through placebo inhalation devices of the most common breath-actuated CFC-free inhalers in the market for the three main glucocorticosteroids Budesonide [Turbohaler (TH), dry powder inhaler (DPI)], Beclomethasone dipropionate [Autohaler (AH), breath-actuate…
Inhaler mishandling remains common in real life and is associated with reduced disease control
2011
SummaryProper inhaler technique is crucial for effective management of asthma and COPD. This multicentre, cross-sectional, observational study investigates the prevalence of inhaler mishandling in a large population of experienced patients referring to chest clinics; to analyze the variables associated with misuse and the relationship between inhaler handling and health-care resources use and disease control.We enrolled 1664 adult subjects (mean age 62 years) affected mostly by COPD (52%) and asthma (42%). Respectively, 843 and 1113 patients were using MDIs and DPIs at home; of the latter, the users of Aerolizer®, Diskus®, HandiHaler® and Turbuhaler® were 82, 467, 505 and 361.We have a tota…