Rapid pressure-less and spark plasma sintering of (Ba0.85Ca0.15Zr0.1T0.9)O3 lead-free piezoelectric ceramics

This work shows for the first time the possibility to sinter BCZT powder compacts by rapid heating rates within one hour of sintering, while achieving good piezoelectric properties. The sintering was performed by rapid (heating rates 100 and 200 °C/min) pressure-less sintering (PLS) at 1550 °C/5-60 min and by SPS sintering (100 °C/min, 1450 °C/5?60 min and 1500 °C/15?45 min). The rapid PLS samples reached a relative density up to 94 % and grain sizes of 17–36 μm acquiring d₃₃ up to 414 pC/N. Although the SPS samples reached full density at 1450 °C, their piezoelectric properties worsened due to smaller grains (10?15 μm) as well as formation of cracks at dwell times > 30 min. At elevated SPS temperature of 1500 °C/30 min, the d₃₃ increased to 360 pC/N sustaining full density. Even higher increase in d₃₃ (424 pC/N) of SPS samples was achieved by post-rapid PLS at 1550 °C/60 min resulting from further expansion in grain size.     

Convex powerdomains I

A completion via Frink ideals is used to define a convex powerdomain of an arbitrary continuous lattice as a continuous lattice. The powerdomain operator is a functor in the category of continuous lattices and continuous inf-preserving maps and preserves projective limits and surjectivity of morphisms; hence one can solve domain equations in which it occurs. Analogous results hold for algebraic lattices and bounded complete algebraic cpo's.     

Rubber substrates and their influence on isomerization of conjugated dienes in pheromone dispensers

Release rate and degree of isomerization of pheromones with conjugated double bonds were studied in dispensers prepared from several rubber substrates. The substrates compared were made of rubber, cured with elemental sulfur or accelerators based on organic sulfur compounds or organic peroxides. Isomerization of the double bonds occurs immediately after impregnation of the substrate, and the degree of isomerization increases during field use and/or storage. The propensity of the isomers to isomerize corresponds to their proportion in the equilibrium mixture. AnE,Z isomer is isomerized faster than theE,E isomer, and finally a near-equilibrium mixture of the four isomers is present. Minimal isomerization was found in non-sulfur-cured substrates which are the material of choice.     

Memory effects on symptom reporting in a respiratory learning paradigm.

With odors as conditioned stimuli (CSs) and CO?-enriched air as the unconditioned stimulus, participants learned to exhibit respiratory responses and somatic complaints on presentation of only the odor CS+. Studied was whether complaints during CS+-only trials were inferred from the conditioned somatic responses or were based on activated memory of the complaints during acquisition. Participants (N?=?56) were either attentionally directed away or not from the complaints during acquisition, and the effects on somatic complaints during test were studied. Respiratory responses, heart rate, and somatic complaints were measured. No physiological conditioning effects were found. However, more complaints were reported to the CS+ than to the CS– odor, but only when the CS+ was foul smelling. This effect was modulated by the attention manipulation, showing that the learned complaints during the test phase were based on memory of the acquisition complaints and not on physiological responses during the test. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The structure and properties of materials used in advanced drug delivery systems

The various requirements placed on materials that might serve as suitable components in drug delivery systems are discussed. Special attention is paid to the interactions between the drug delivery constructs and the biological environment, using the interactions in the vascular compartment of the body as an example. Two alternative general approaches are compared: (a) “controlled drug release”, which aims to reduce or eliminate side effects by producing a steady therapeutic concentration of drug in the body; (b) “site-selective drug delivery”, which aims to ensure that the drug is delivered to the site of its biochemical and disease-related site of action, at the same time maintaining the drug inactive elsewhere in the body. It is concluded that materials for delivering drugs to selected sites of disease within the body must be designed to utilise the unique features (structure, function, rhythm) of the main elements involved in the disease. Equally important is to design drug carriers that do not interact non-specifically within the body so that their specific action would be prevented. It is difficult to see how this could be achieved using materials entirely “foreign” to the body. Utilising the primary structures used by the biological systems (proteins, glycoproteins, carbohydrates) and creating novel higher structures (secondary, tertiary, quartenary) that mimic the native material is the logical way forward in the search for new drug delivery systems, and we need to turn more and more to the molecular basis of biology for guidance and inspiration.     

A comparative study of a fluidised bed reactor and a gas lift loop reactor for the ibe process: Part III. Reactor performances and scale Up

Continuous fermentations using Clostridium spp. DSM 2152 immobilised in calcium alginate beads to produce butanol and isopropanol from glucose were carried out in a fluidised bed reactor with liquid recycle (FBR, 10.9 dm³ working volume, 41 % solids) and in a gas lift loop reactor (GLR, 11.4 dm³ working volume, 32% solids). In the FBR in-situ produced non-coalescing gas bubbles had a negligible influence on the fluidisation pattern and the steady state results of the fermentation were in accordance with those predicted by a reactor model. The FBR was operated reliably for 5 weeks without decrease of activity. The GLR behaved as a three phase reactor because of the recycled fermentation gas. The steady state fermentation results were as predicted by the GLR model. Scale up to a 50 m³ FBR and a 65 m³ GLR led to development of a plug flow with recycle model for the FBR and a stirred tank model for the GLR. On the basis of overall reactor performance and ease of integration with a simultaneous product recovery the FBR is preferred to the GLR for application in a large scale butanol/isopropanol process using immobilised Clostridia spp.     

Optimization methods and available software. Part 1

Optimization theories and generally applied optimization techniques are reviewed. The versatility and the complexity anticipated in actual problems are simplified to enable the food practitioners interested in the subject to overcome some of the barriers which prevented full utilization of optimization. The paper summarizes the various mathematical methods available for solving problems of product and process optimization and provides information and advice concerning the advantages and limitations of each technique. A compiled list of optimization subroutines, guidelines and criteria for choosing the proper software are furnished.