Ageing studies on some titania gels

Hydrous titania gels, precipitated from titanous chloride and aged in different aqueous media have different textural, thermal and structural properties as demonstrated by nitrogen adsorption, differential thermal analysis, X-ray diffraction and scanning electron microscopy studies. Ageing in ammonia leads to the development of microporosity, whereas ageing in water causes an extension of the pore system in the primary particles with little change in the surface texture. Heat-treatment of the precipitated gels prior to ageing seems to afford a certain stability to the primary particle by allowing hydroxo and oxo bridges to be formed, thus leading to the formation of a more rigid structure. The nature of the ageing medium and its effect on the inner coordination sphere of the titanium ions are important parameters affecting the textural and thermal behaviours of the titania gels.     

Instron texture profile of buffalo milk cheddar cheese as influenced by composition and ripening changes

Buffalo milk Cheddar cheese samples of different ages were analysed for compositional attributes (CA), ripening indices (RI) and Instron Textural Profile (ITP). All samples were compositionally alike, except for pH and salt-in-moisture (SM) contents. RI showed significant variations. CA and RI showed highly significant correlations within themselves and with each other, except for moisture with pH, SM with moisture, MNFS, Fat and FDM and Fat with MNFS. The ITPs of cheeses showed significant variations and had highly significant intercorrelations indicating their interdependence. CA (except moisture and MNFS) and RI showed a highly significant correlationship with ITPs. Moisture content showed a highly significant correlationship with all ITPs, except cohesiveness and springiness, where it was significant. MNFS content showed significant correlations only with hardness and brittleness. Stepwise regression analysis revealed that MI was the most predominant factor influencing cheese texture, followed by pH, SM, FDM and TVFA. Knowing Ca and RI, the textural properties of cheeses can be forecast through mathematical equations. Similarly the age of cheese can also be predicted if RI and/or textural properties are known.     

The Change of Body Temperature During Convective Drying of Cube-Shaped Apple Pieces

When using the convective drying method, the mass transfer between drying air and moisture diffusion of the material is very important. The moisture moves inside the material because of the volume change caused by the increased temperature. This movement is additionally affected by the texture of the material. According to the research dealing with colloid capillary porous texture of vegetables and fruit, the humidity migration inside the material occurs in both fluid and steam condition at the same time. This migration is stimulated by the heating and decreasing humidity along with the flow. In this research, winter varieties of apples (Jonathan, Golden Delicious, and Idared) were studied by heating of a 20 × 20 × 20 piece of apple with a thermocouple in it. On the basis of the measurements it can be stated that for the fruits with a high percentage of moisture (75-90%), when making the drying condition, the moisture gradient is influenced by the fractured cells of the cut area. It was found that the variety of apple is very important in relation to the heating and water loss gradient. According to the results, the wet volume change due to the heating highly influences the water loss. The models that describe the temperature of the material have a connection with the water loss.     

Effect of pretreatments and freezing rate on the firmness of potato tissue after a freeze–thaw cycle

The texture of potato tissue after a freeze–thaw process using different freezing rates and different pretreatments was analysed, in order to select the best strategy for optimum preservation of the textural characteristics of pre‐frozen potato. Ten blanching conditions were tested and a two‐step blanching process with calcium chloride (0.07 g mL^?1) proved the most effective in protecting the tissue after a freeze–thaw process (maximum load force around 10–55% of the raw tissue, depending on potato batch, for air‐blast freezing and 20–60% for immersion freezing). Vacuum impregnation at 100 and 400 mbar, even when followed by different pre‐drying treatments to remove excess water, was very detrimental to resistance to a freeze–thaw process (maximum load force below 10% of the raw tissue for air‐blast freezing and below 20% for immersion freezing). Microstructure analysis confirmed better tissue integrity retention with ethyleneglycol immersion freezing instead of air‐freezing. Differences were found between batches with a 6‐month difference in storage time, indicating that the fresher batch was more suitable for freezing.     

Use of ultrafiltration for preparing improved tomato pulp

The characteristics of high-quality tomato pulp (commercial def.: crushed or diced tomatoes with about 30% tomato juice as packing medium) canned with tomato juice pulp enriched by ultrafiltration as packing medium were compared with those covered with conventional vacuum-concentrated juice.
Both hot- and cold-break products were prepared and those containing 20% serum-reduced packing juice proved to be the best, showing no signs of syneresis on storage and with improvements in sensory properties, colour and non-enzymatic browning; some volatile components were reduced.     

Bi-based superconductors fabricated in high magnetic fields

The microstructure and superconducting properties of Bi-2223 superconductor fabricated in high magnetic fields were investigated. The results shows that the Bi-2212 grains with their c-axis parallel to the magnetic field were formed after the partial-melting and solidification in 8 T magnetic field, and transformed into the Bi-2223 grains with c-axis alignment during the further sintering process at 840 ℃ without magnetic field. The conversion of Bi-2212 grains to Bi-2223 grains has the heredity in grain alignment. The mixed structures of the Bi-2223 and the Bi-2212 grains with their c-axis parallel to the magnetic field are formed in samples sintered at 850-855 ℃ in 10 T magnetic field. When sintered in 10 T below 845 ℃, a high proportion of Bi-2223 phase is obtained, however no preferred orientation is observed. The Bi-2223 grains with their c-axis parallel to the axial direction of the vertical tube furnace are formed not only on the surface, but also in the center of the sample sintered at 850 ℃ for 120 h in a 15 ℃/cm temperature gradient without magnetic field. Moreover, the samples sintered in the temperature gradient and in a 10 T magnetic field have a stronger c-axis alignment ofbi-2223 phase.     

Analogy and duality of texture analysis by harmonics or indicators

According to the classic harmonic approach, an orientation density function (odf)f is expanded into its corresponding Fourier orthogonal series with respect to generalized spherical harmonics, and a pole density function (pdf) into its corresponding Fourier orthogonal series with respect to spherical harmonics. While pdfs are even (antipodally symmetric) functions, odfs are generally not. Therefore, the part of the odf which cannot be determined from normal diffraction pdfs can be mathematically represented as the odd portion of its series expansion. If the odff is given, the even part can be mathematically represented explicitly in terms off itself. Thus, it is possible to render maps ofharmonic orientation ghosts, and to evaluatevariants of mathematical standard odfs resulting in identical pdfs independent of pdf data. However, if only normal diffraction pdfs are known, the data-dependentvariation width of feasible odfs remained unaccessible, and within the harmonic approach a measure of confidence in a solution of the pdf-to-odf inversion problem does not exist.According to any discrete approach, an odff defined on some setG of orientations is expanded into its corresponding Fourier orthogonal series with respect to indicator functions of the elements of a partition ofG, and a pdf defined on the upper (lower) unit hemisphereS ₊ ^{3 3} into its corresponding Fourier orthogonal series with respect to indicator functions of the elements of a partition ofS ₊ ³ . The ambiguity of the pdf-to-odf inversion problem is discussed in terms of column-rank deficiency of the augmented projection matrix. The implication of the harmonic approach to split an odf into auniquely determined and anundetermined part does no longer seem to be reasonable. However, it is possible to numerically determine data-dependent confidence intervals for the Fourier coefficients with respect to the indicator functions which can be immediately interpreted as mean orientation densities within the elements of the partition ofG. Doing so for all Fourier coefficients in the finite series expansion, i.e. for all elements of the partition of the setG, eventually results in the data-dependent variation width of odfs feasible with respect to given pdf data, and to the partitions ofG andS ₊ ³ .Thus it is confirmed that the appearance of orientation ghosts, in particular correlations oftrue andghost orientation components, depends on the representation of an odf. It may be questioned whether in practical applications the implicit assumption of the harmonic method that the even part can be determined uniquely and free of error is generally a reasonable initial condition to develop ghost correction procedures.     

Surface texture analysis based upon the visually acquired perturbation of surface normals

A novel technique has been developed for the textural analysis of Lambertian surfaces while in the presence of a variable albedo. The method has direct application for the surface quality determination of cosmetically sensitive components, and has particular application where more traditional methods may prove unsatisfactory. A photometric stereo technique is used to facilitate the isolation of localised irregular features, such as scratching, indentations or small protrusions, which may be obscured by a coincident, regular or random surface albedo. A generic lighting arrangement is employed, which obviates the need for a customised lighting configuration. This represents a significant advantage for the configuration of industrial vision-based inspection systems. Promising experimental results have been obtained using example components, and are presented in the paper.