Monitoring of thermal therapy based on shear modulus changes: II. Shear wave imaging of thermal lesions

The clinical applicability of high-intensity focused ultrasound (HIFU) for noninvasive therapy is currently hampered by the lack of robust and real-time monitoring of tissue damage during treatment. The goal of this study is to show that the estimation of local tissue elasticity from shear wave imaging (SWI) can lead to a precise mapping of the lesion. HIFU treatment and monitoring were respectively performed using a confocal setup consisting of a 2.5-MHz single element transducer focused at 34 mm on ex vivo samples and an 8-MHz ultrasound diagnostic probe. Ultrasound-based strain imaging was combined with shear wave imaging on the same device. The SWI sequences consisted of 2 successive shear waves induced at different lateral positions. Each wave was created with pushing beams of 100 μs at 3 depths. The shear wave propagation was acquired at 17,000 frames/s, from which the elasticity map was recovered. HIFU sonications were interleaved with fast imaging acquisitions, allowing a duty cycle of more than 90%. Thus, elasticity and strain mapping was achieved every 3 s, leading to real-time monitoring of the treatment. When thermal damage occurs, tissue stiffness was found to increase up to 4-fold and strain imaging showed strong shrinkages that blur the temperature information. We show that strain imaging elastograms are not easy to interpret for accurate lesion characterization, but SWI provides a quantitative mapping of the thermal lesion. Moreover, the concept of shear wave thermometry (SWT) developed in the companion paper allows mapping temperature with the same method. Combined SWT and shear wave imaging can map the lesion stiffening and temperature outside the lesion, which could be used to predict the eventual lesion growth by thermal dose calculation. Finally, SWI is shown to be robust to motion and reliable in vivo on sheep muscle.     

Transparent ceramics green-microstructure optimization by pressure slip-casting: Cases of YAG and MgAl2O4

This paper presents experimental data and its interpretation regarding the forming of YAG and spinel green-bodies, intended for transparent parts fabrication, by the pressure slip casting (PSC) method. Conditions for an optimal operation are established based on the modeling of the filtration kinetics. It emerges that the method is able to provide highly sinterable green parts by ensuring that the cakes porosity exhibits low average size and narrow size distribution. Results were compared with other popular forming approaches like slip casting (SC) and cold isostatic pressing (CIP). PSC was found as superior, to the other approaches, as far as obtainment of high sinterability green- bodies is concerned. In the case of YAG, it was shown that PSC method even allows the replacement of the traditional long vacuum firings by a two stage densification operation in which an initial air-firing is completed by a hot isostatic pressing step.     

Ion-beam pore opening of porous anodic alumina: The formation of single nanopore and nanopore arrays

Anodized aluminium oxide (AAO) fabricated by electrochemical anodization of aluminium is used as the substrate for focused ion-beam (FIB) fabrication of single nanopore and nanopore arrays. The method is based on the controlled and selective removal of AAO barrier oxide film by FIB milling. FIB process with different milling conditions is applied to open single nanopores (diameter of 60 nm) or circular nanopore arrays with a different number of opened pores on AAO substrate. This process combines a low cost AAO substrate and FIB milling, and offers an economically viable alternative for the fabrication of nanopore devices with controlled dimensions for a range of applications in nanofluidics, molecular separations and biosensing.     

Nanofiltration and reverse osmosis of model process waters fromthe dairy industry to produce water for reuse

In dairy plants the process waters generated during the starting, equilibrating, interrupting and rinsing steps contribute to the production of effluents. They correspond to milk products (milk, whey, cream) diluted with water without chemicals. The treatment of these dairy process waters by nanofiltration (NF) or reverse osmosis (RO) operations was proposed to concentrate dairy matter and to produce purified water for reuse in the dairy plant. The study reports one-stage and two-stage (NF + RO and RO + RO) spiral-wound membrane treatments with five model process waters representative of the main composition variations observed in dairies. Performances (permeate flux, milk components rejection, purified water characteristics) of the different operations were compared. Discussion was focused on the comparison between quality of produced waters and vapour condensates (from product drying and evaporation processes) reused in dairy plants. Accordingly, both total organic carbon (TOC) and conductivity of water treated by a single RO or NF + RO operations were convenient for reuse as heating, cooling, cleaning and boiler feed water. With the two-stage RO + RO process, a more purified water complying with the TOC drinking water limit was achieved.     

Fabrication of Carbon Multiwall Nanotube/Polymer Composites by Shear Mixing

The dispersion of nanotubes in polymer matrices has been investigated as a means of deriving new and advanced engineering materials. These composite materials have been formed into fibers and thin films and their mechanical and electrical properties determined. The nanotube concentration at which conductivity was initiated (the percolation threshold) varied with host polymer. In poly(propylene), this was as low as 0.05 vol.‐%, while higher concentrations were required for polystyrene and particularly for ABS. There was a small increase in elastic modulus and decrease in tensile strength at low nanotube loading, but as the concentration was increased there was a progressive increase in both strength and stiffness.     

Chemical and physical methodologies for the replacement/reduction of sulfur dioxide use during winemaking: review of their potentialities and limitations

Sulfur dioxide (SO₂) is probably one of the most versatile and efficient additives used in winemaking due to its antiseptic and antioxidant properties. This compound is also important for minimizing phenolic polymerization rate and color loss during wine aging. However, allergies caused by SO₂-derived compounds, namely the sulfites, are becoming more frequent, causing symptoms such as headaches, nausea, gastric irritation, and breathing difficulties in asthma patients. Consequently, the legislated maximum concentration of SO₂ allowed in wines has been gradually reduced. For this reason, it is crucial in a competitive global winemaking market strategy, to reduce or even eliminate the use of SO₂ as a preservative and to search for new healthier and safe strategies. This work gives an overview of the main methodologies that have been proposed so far and that have potential to be used in winemaking as an alternative to SO₂. The addition of compounds such as dimethyl dicarbonate, bacteriocins, phenolic compounds, and lysozyme, and the use of physical methods, namely pulsed electric fields, ultrasound, ultraviolet radiation, and high pressure are discussed and critically evaluated.     

A spatiotemporal analysis of public pharmaceutical expenditure

A regression model for per capita public pharmaceutical expenditure, based on aggregate data from fifty Spanish provinces, observed annually for the period 1996–2002 is analyzed. The necessity of simultaneously controlling for dynamic patterns and spatial autocorrelation is demonstrated. As the aim of the present and related studies of small-area variation is to control for spatial association rather than to formulate it as an explicit part of a model, the traditional application of parametric spatial autocorrelation or spatial autoregression specifications seems unnecessarily restrictive and superfluous. The present study analyzes the effects of spatial association using a non-parametric spatial filtering approach. The importance of adjusting for spatial association is confirmed, but it is further shown that the parametric and the non-parametric approaches may lead to substantially different conclusions regarding explanation of pharmaceutical expenditure variations. Thus, the need for further evidence on the implications of spatial association—and the recognition that this is more than just spatial autocorrelation and/or spatial autoregression—when analyzing complex large area behavior using small area data is demonstrated.