Wetting of Aluminum Nitride by Nickel Alloys

The effect of the addition of alloying elements to Nion Ni wetting of AIN was investigated. Pure Ni is nonwetting, but adding Hf, Zr, or Ti caused Ni to wet, whereas V, Nb, Ta, Cr, Mo, and W did not change the wetting angle. In wetting systems, the alloying elements form nitrides and the change in the wetting angle is related to the change in the Gibbs free energy of formation of the nitrides formed in the contact layer.     

Quantification of structural changes in acute inflammation by fractal dimension,angular second moment and correlation

The aim of the study was to examine alteration and possible application of fractal dimension, angular second moment, and correlation for quantification of structural changes in acutely inflamed tissue. Acute inflammation was induced by injection of turpentine oil into the right and left hind limb muscles of mice, whereas control animals received intramuscular saline injection. After 12 h, animals were anesthetised and treated muscles collected. The tissue was stained by hematoxylin and eosin, digital micrographs produced, enabling determination of fractal dimension of the cells, angular second moment and correlation of studied tissue. Histopathological analysis showed presence of inflammatory infiltrate and tissue damage in inflammatory group, whereas tissue structure in control group was preserved, devoid of inflammatory infiltrate. Fractal dimension of the cells, angular second moment and correlation of treated tissue in inflammatory group decreased in comparison to the control group. In this study, we were first to observe and report that fractal dimension of the cells, angular second moment, and correlation were reduced in acutely inflamed tissue, indicating loss of overall complexity of the cells in the tissue, the tissue uniformity and structure regularity. Fractal dimension, angular second moment and correlation could be useful methods for quantification of structural changes in acute inflammation.     

Enamel alteration following tooth bleaching and remineralization

The purpose of this study was to compare the effects of professional tooth whitening agents containing highly concentrated hydrogen peroxide (with and without laser activation), on the enamel surface; and the potential of four different toothpastes to remineralize any alterations. The study was performed on 50 human molars, divided in two groups: treated with Opalescence^® Boost and Mirawhite^® Laser Bleaching. Furthermore, each group was divided into five subgroups, a control one and 4 subgroups remineralized with: Mirasensitive^® hap+, Mirawhite^® Gelle?, GC Tooth Mousse? and Mirafluor^® C. The samples were analysed by SEM/3D‐SEM‐micrographs, SEM/EDX‐qualitative analysis and SEM/EDX‐semiquantitative analysis. The microphotographs show that both types of bleaching cause alterations: emphasized perikymata, erosions, loss of interprizmatic substance; the laser treatment is more aggressive and loss of integrity of the enamel is determined by shearing off the enamel rods. In all samples undergoing remineralization deposits were observed, those of toothpastes based on calcium phosphate technologies seem to merge with each other and cover almost the entire surface of the enamel. Loss of integrity and minerals were detected only in the line‐scans of the sample remineralized with GC Tooth Mousse?. The semiquantitative EDX analysis of individual elements in the surface layer of the enamel indicates that during tooth‐bleaching with HP statistically significant loss of Na and Mg occurs, whereas the bleaching in combination with a laser leads to statistically significant loss of Ca and P. The results undoubtedly confirm that teeth whitening procedures lead to enamel alterations. In this context, it must be noted that laser bleaching is more aggressive for dental substances. However, these changes are reversible and can be repaired by application of remineralization toothpastes.     

EFFECT OF NATIVE AND LYOPHILIZED KEFIR GRAINS ON SENSORY AND PHYSICAL ATTRIBUTES OF WHEAT BREAD

Native and lyophilized kefir grains were added directly to bread dough or as a starter in sourdough. Because of inadequate leavening activity of kefir, yeast‐leavened breads were prepared. Kefir addition influenced the quality attributes and the shelf life of wheat bread. The pH of bread containing kefir decreased as compared to that in the control bread. The acidity of bread with kefir increased as compared to that in the control bread. An addition of kefir grains, regardless of the form, lowered the bread volume and increased the mold‐free shelf life from 4 (control) to 5–7 days. The addition of kefir grains in bread dough contributed to a milder taste, a more delicate yogurt‐like or dairy aroma. The breads made with sourdoughs containing native or lyophilized kefir grains scored higher for crumb quality number than breads made by directly adding kefir grains.     

Exact linearization in switched-mode DC-to-DC power converters

Three popular DC-to-DC switched mode power converters—Buck, Boost, and Buck-Boost—are shown to be in the same orbit of structural equivalence as a second-order controllable circuit in Brunovsky canonical form. The equivalence is achievable under non-linear feedback and explicit local difleomorphic state coordinate transformations. The implications of local exact linearizability of this class of systems in the design of Variable Structure Feedback Control laws or Pulse-Width-Modulation strategies is thoroughly discussed.