Control of grain boundary in alumina doped CCTO showing colossal permittivity by core-shell approach

Grain boundaries of CaCu₃Ti₄O₁₂ (CCTO) materials have been shown to play leading role in colossal permittivity. Core-shell design is an attractive approach to make colossal dielectric capacitors by controlling the grain boundaries. Core-shell grains of CCTO surrounded by Al₂O₃ shell were synthesized by ultrasonic sol-gel reaction from alumina alkoxide precursor. The influence of alumina shell by comparison with bare CCTO grains was studied. Particularly, microstructure, dielectric and electric effects on sintered ceramics are reported. The average grain size and the density are increased compared to undoped CCTO leading to an improvement of permittivity from 58,000 to 81,000 at 1?kHz. Furthermore a decrease of dielectric loss is found in a frequency range of 10²–10³?Hz. Moreover, the activation energy of grain boundaries is increased from 0.55 to 0.73?eV and the electrical properties such as breakdown voltage, non-linear coefficient and resistivity are improved with the aim of making industrial capacitors.     

Transformations of polyhedral carbon nanoparticles under high pressures and temperatures

Pressure–temperature-induced transformations of polyhedral carbon nanoparticles (PCN) and their binary mixture with naphthalene have been studied at 8 GPa and temperatures up to 1600 °C by X-ray diffraction, small-angle X-ray scattering, Raman spectroscopy, scanning and transmission electron microscopies. Qualitative distinction of the mechanism of PCN transformations in the single-component carbon system from binary hydrocarbon system has been established. The distinguishing feature of the solid-phase PCN transformation in single component system at temperatures above 1000 °C is their structural reorganization associated with the formation of carbonaceous cores with different morphologies, filling the internal cavities of starting PCNs. The structural transformations of PCN may also give rise to alteration of their external polyhedral shape. However, in the entire studied pressure–temperature region, the solid-phase transformations are limited to individual PCNs with the initial sizes in the 30–80 nm range. The combined solid–gas (fluid) phase transformations of PCN at 8 GPa in the hydrogen-containing system are associated with the destruction of PCN already at ∼900 °C and subsequent cumulative recrystallization of decomposition products. The latter process results in formation of micron-sized crystallites of graphite at 1000 °C and diamond at temperatures above 1100 °C.     

Low temperature synthesis of Co3O4 and (Co1−xMnx)3O4 spinels nanoparticles

The (Co_1?xMn_x)₃O₄ solid solution have been synthesized in water at 60 °C by soda addition to a cationic solution. XRD patterns show that spinel oxide has been obtained except for pure cobalt composition which exhibits also the presence of hydroxide and oxy-hydroxide. Therefore, to reach this composition, a different synthesis route has been developed: the cationic solution is added to the soda and for the first time Co₃O₄ nanoparticles have been synthesized by a direct precipitation in aqueous solution at low temperature. For each composition, the particles are well crystallized and exhibit a size close to 50 nm. Each particle is composed by several crystallographic domains of about 10 nm. The cubic to tetragonal transition reported in the literature for x = 0.46 is observed in between x = 0.33 and x = 0.50. Raman spectra show that substitution of Co by Mn, in the cubic phase, introduces a random high disorder. In the tetragonal phase, occupation of the octahedral site remains a random occupation, while the tetrahedral site seems to be preferentially occupied by Co ions. All these results show that the precipitation is a simple, fast and safe process to synthesize pure phase of (Co_1?xMn_x)₃O₄ spinel solid solution in aqueous media at low temperature.     

Nanohybrids with Magnetic and Persistent Luminescence Properties for Cell Labeling,Tracking, In Vivo Real‐Time Imaging,and Magnetic Vectorization

Once injected into a living organism, cells diffuse or migrate around the initial injection point and become impossible to be visualized and tracked in vivo. The present work concerns the development of a new technique for therapeutic cell labeling and subsequent in vivo visualization and magnetic retention. It is hypothesized and subsequently demonstrated that nanohybrids made of persistent luminescence nanoparticles and ultrasmall superparamagnetic iron oxide nanoparticles incorporated into a silica matrix can be used as an effective nanoplatform to label therapeutic cells in a nontoxic way in order to dynamically track them in real‐time in vitro and in living mice. As a proof‐of‐concept, it is shown that once injected, these labeled cells can be visualized and attracted in vivo using a magnet. This first step suggests that these nanohybrids represent efficient multifunctional nanoprobes for further imaging guided cell therapies development.     

In vivo 2D magnetic resonance spectroscopy of small animals

Localized in vivo NMR spectroscopy, chemical shift imaging or multi-voxel spectroscopy are potentially useful tools in small animals that are complementary to MRI, adding biochemical information to the mainly anatomical data provided by imaging of water protons. However the contribution of such methods remains hampered by the low spectral resolution of the in vivo 1D spectra. Two-dimensional methods widely developed for in vitro studies have been proposed as suitable approaches to overcome these limitations in resolution. The different homonuclear and heteronuclear sequences adapted to in vivo studies are reviewed. Their specific contributions to the spectral resolution of spectroscopic data and their limitations for in vivo investigations are discussed. The applications to experimental models of pathological processes or pharmacological treatment in mainly brain and muscle are presented. According to their combined sensitivity, acquisition duration and spatial resolution, the heteronuclear 2D experiments, which are mainly used for ¹H detected-¹³C spectroscopy after administration of ¹³C-labeled compounds, appear to be less efficient than ¹H detected-¹³C 1D methods at high field. However, the applications of 2D proton homonuclear methods show that they remain the best tools for in vivo studies when an improved resolution is required.     

Incineration of municipal and assimilated wastes in France: assessment of latest energy and material recovery performances

Incineration has an important place in waste management in France. In 2003, around 130 incineration plants have treated 12.6 Mt of non-dangerous waste, mainly composed of household waste (10.8 Mt), non-dangerous waste from industry, business, services (1.0 Mt), sewage sludge (0.2 Mt) or clinical waste (0.1 Mt). The incineration of these wastes generated 3.0 Mt of bottom ash of which 2.3 Mt were used for roads construction and 0.2 Mt of ferrous and non-ferrous metal were recycled. It also produced 2,900,000 MWh of electricity, of which 2,200,000 MWh were sold to Electricité de France (EDF) and 9,100,000 MWh of heat, of which 7,200,000 MWh were sold to private or public users. These French incinerators of non-hazardous waste are currently being thoroughly modernized, thus making possible the consolidation and the enhancement of their environmental and energy performance. This process is related to the implementation of the European Directive 2000/76/CE whose expiration date is 28 December 2005. Upon request of ADEME, the engineering company GIRUS has realised the first technical and economical evaluation of works necessary to bring incinerators into compliance. The financial estimations, carried out in 30 June 2003, show that the investments to be devoted could reach 750 million euros. This assessment shed new light on the situation of non-hazardous waste incinerators, including an identification and a rank ordering for each incinerator of the most frequent and the most complex non-conformities to be solved in term of cost and delay. At last, this assessment gives the solutions for each non-compliance.     

Fast Batch to Continuous Solid‐Liquid Extraction from Plants in Continuous Industrial Extractor

In this work, the continuous extraction of solute from vegetable matrix has been studied. An industrial apparatus was used to acquire information for process implementation. To this end, a batch study was conducted to obtain the extraction kinetics, and the behavior of the matter under pressure and raw plant transport were investigated. Coupling these elements allows the representation of the extraction yields according to time in the apparatus. A methodology for the change from batch to continuous extractor based on laboratory tests is proposed.     

Esophageal involvement after tetracycline ingestion

Between 1985 and 1992, 81 spontaneous oesophageal injuries associated with tetracycline were notified to the French Regional Pharmacovigilance Centres. The side effects were oesophageal ulcers (79 per cent), esophagitis (11 per cent) and dysphagia (10 per cent). Esophagitis and dysphagia appeared sooner (4 days) than the ulcers (15 days). The mean age of the patients was 29 +/ 13 years and 73 per cent were women. In 92 per cent of cases, the recommendations for administration were not observed (medication taken at bedtime with not enough or without water). With 96 per cent of patients, doxycycline was the tetracycline in question; this prevalence could be explained by its irritant and cytotoxic properties. The oesophageal injuries were 22 times more frequent with capsules than with tablets, because of their easier adhesion to the oesophageal surface. Oesophageal injuries are potentially serious and must be avoided by clear information to patients and prescribers on tetracycline administration; consumption in the middle of a meal with an adequate quantity of water and never less than one hour before bedtime.