Tetragonal zirconia: Wet chemical preparation, mechanical and electrical properties

Yttria-stabilized zirconia powders were prepared in the composition range of 3 to 13 at% yttria. The hydrolysis-gel precipitation technique was used, starting from metal alkoxides or chlorides. In the composition range between 5 and 10 at% yttria, the materials sintered at 1250°C have a fully tetragonal structure. The density was higher than 95% and the grain sizes can be varied between 0.1 and 0.5μm depending on the preparation conditions. The fracture toughness KIC amounts 6 to 11 MPam but is not dependent on the composition. The transformation toughening mechanism and the properties of the tetragonal phase itself play an important role in the increase of KIC compared with cubic materials. The magnitude of the oxygen-ion conductivity value is comparable with that for cubic materials

De 'service' klasse in Nederland: een voorstel tot aanpassing van de EGP-klassenindeling

The Erikson Goldthorpe & Portocarero class scheme (EGP) has evolved to the standard indicator of class positions in international research. Critique with respect to the EGP service class is related to criticism regarding `The Constant Flux' (Erikson & Goldthorpe 1992). This work is mainly concerned with the classical theme of the shift from agriculture to industry and it neglects the important `post?industrial' distinction between the industrial and service sector. This criticism particularly applies to the `service class' as conceptualized by the EGP class scheme. It does not take important institutional changes in post-industrial society into account. Consequently, the life styles and beliefs of the 'service class' show a large amount of variation. We therefore propose to modify the EGP-class scheme by distinguishing the `social and cultural specialists' within the service class. Using the Dutch Family Survey (1992/93) we show that this adjustment of the EGP?class scheme is an improvement with respect to the explanation of a variety of attitudes and behaviour. The finding that our results hold after controlling for relevant predictors such as education, signifies the importance of our revision of the EGP-class scheme

Development and Application of 3-Dimensional Transmission Electron Microscopy (3D-TEM) for the Characterization of Metal-Zeolite Catalyst Systems

With electron tomography (3D-TEM) a 3D-reconstruction is calculated from a series of TEM images taken at a tilt angle range (tilting range) of +70° to -70°. The reconstruction can be visualized with contour surfaces that give information about the surface of the sample as well as with slices through the reconstruction that give detailed information on the interior of the sample. Electron tomography gives much more information than Scanning Electron Microscopy (SEM), since SEM gives only information about the surface of a sample. As a case study, the imaging of silver clusters on zeolite NaY is given. The reconstruction shows silver particles at the external surface as well as a silver particle in a mesopore of the zeolite crystallite. It is concluded that 3D-TEM comprises a breakthrough in the characterization of nano-structured solid catalysts

A Musical instrument in MEMS

In this work we describe a MEMS instrument that resonates at audible frequencies, and with which music can be made. The sounds are generated by mechanical resonators and capacitive displacement sensors. Damping by air scales unfavourably for generating audible frequencies with small devices. Therefore a vacuum of 1.5 mbar is used to increase the quality factor and consequently the duration of the sounds to around 0.25 s. The instrument will be demonstrated during the MME 2010 conference opening, in a musical composition especially made for the occasion

Shigellosis and AIDS : Report of a case and brief review of the literature

Contains fulltext : 4491.pdf (publisher's version ) (Open Access

De relatie tussen wateraanvoer, verdamping en produktie bij het gewas aardappelen. Verslag van een veldproef op het proefterrein Sinderhoeve in 1981

Door intensivering van de akkerbouw- en de vollegrondsgroeteteeltbedrijven neemt de behoefte aan watervoorziening voor de gewassen toe. De wateronttrekking door industrie en drinkwaterbedrijven neemt eveneens toe. In verband daarmee wordt de kennis van de relatie tussen watervoorziening en de gewasproduktie gewasverdamping steeds belangrijker

De relatie tussen wateraanvoer, verdamping en produktie bij het gewas aardappelen: Verslag van een veldproef op het proefterrein Sinderhoeve in 1982

De relatie tussen wateraanvoer, verdamping en produktie bij het gewas aardappele

Eating behaviour and retro-nasal aroma release in normal-weight and overweight adults: a pilot study

Eating rate and bite size are important factors affecting food intake, and we hypothesise the underlying role of oral sensory exposure in this. However, the latter currently lacks objective measuring parameters, but an interesting measure could be the extent of in vivo retronasal aroma release. Second, the literature is ambiguous about overweight subjects differing from normal-weight subjects in eating behaviour. Consequently, we investigated: (1) whether eating behaviour (food intake, eating rate, bite size, number of bites and meal duration) relates to weight status and (2) whether the extent of retro-nasal aroma release relates to eating behaviour and weight status. A matched group (sex, age and dietary restraint) of twenty-seven normal-weight (BMI 21.8 (SD 1.6) kg/m(2)) and twenty-seven overweight/obese subjects (BMI 30.5 (SD 5.8) kg/m(2)) consumed a spiced rice meal and apple pie yogurt on separate test days. The extent of retro-nasal aroma release was measured on a third test day. Mean bite size for spiced rice was significantly (P=0.03) larger in overweight/obese (10.3 (SD 3.2) g) v. normal-weight subjects (8.7 (SD 2.1) g). There were no other significant differences in eating behaviour or retro-nasal aroma release between the groups. Eating behaviours were not correlated with BMI or retro-nasal aroma release. Subjects showed consistent eating behaviour for both test products. Eating behaviour might be a characteristic of an individual but not by definition a characteristic for a group of people based on their weight. Given the large sample sizes, necessary according to a posteriori sample size calculations, one needs to consider the relevance of finding a statistically significant difference in eating behaviour between the weight groups in a laboratory setting