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Abstract

In this paper the effect of soldering technique and thermal shock test were investigated on SAC 305 solder joints, produced by two different solder method. The solder joints were subjected to different cycle numbers up to 5000 thermal shock tests with two different thermal profiles of –30/+110°C and –40/+125°C. Microstructural properties of the tested joints were examined with the focus on intermetallic layer thickness and crack formation/propagation. Thickness of the scallop shaped Cu6Sn5 intermetallic layer was increased with increasing cycle number for both THRS and multiwave joints, but the thickening was more effective for the THRS joints. Cracks typically formed at the solder alloy/ PTH barrel and the solder alloy/pin interfaces and propagated along grain boundaries and precipitations of intermetallic compound.
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Abstract

We studied the embryology of Withania somnifera (L.) Dunal by light microscopy in order to reveal specific embryological features of the genus, and compared the results with embryological data on other members of the family Solanaceae. The key embryological characters of W. somnifera include dicotyledonous-type anther wall formation, simultaneous cytokinesis in pollen mother cells, binucleate tapetal cells, 2-celled mature pollen, anatropous, tenuinucellate and unitegmic ovules, polygonum-type embryo sac formation, the presence of an endothelium, and cellular endosperm formation. We give the first report of the dicotyledonous mode of anther wall formation (previously described as basic type) for the species. Comparative study suggests that anther wall formation, number of nuclei in tapetal cells, number of cells in mature pollen, mode of embryo sac formation and endosperm development are the most variable embryological features in Solanaceae. Some of these embryological features of W. somnifera should be of value for comparative study of related species and their phylogenetic relationships within the family.
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Abstract

The embryology of two species, Deschampsia antarctica , a native species, and Poa annua , an alien species in the Antarctic we studied. Flowering buds of plants growing in their natural habitats on King George Island and generative tissues of both plant species grown in a greenhouse were analyzed. Adaptations to autogamy and anemogamy were observed in the flower anatomy of both species. The microsporangia of the evaluated grasses produce a small number of three−celled pollen grains. Numerous pollen grains do not leave the microsporangium and germinate in the thecae. Deschampsia antarctica and P. annua plants harvested in Antarctica developed a particularly small number of microspores in pollen chambers. In D. antarctica , male gametophytes were produced at a faster rate: generative cells in pollen did not become detached from the wall of the pollen grain, they were not embedded in the cytoplasm of vegetative cells, and they divided into two sperm cells situated close to the wall. The monosporous Polygonum type of embryo sac development was observed in the studied species. The egg apparatus had typical polarization, and the filiform apparatus did not develop in synergids. Large antipodals with polyploidal nuclei were formed in the embryo sacs of D. antarctica and P. annua . Poa annua was characterized by numerous antipodal cells which formed antipodal tissue in the chalazal region of the embryo sac. Three distinct antipodals with atypical, lateral position in the vicinity of the egg apparatus were observed in D. antarctica. The diaspores of the investigated grass species were characterized by small size, low weight and species−specific primary and secondary sculpture of the testa and caryopsis coat.
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Abstract

Thermodynamic principles for the dissolution of gases in ionic liquids (ILs) and the COSMO-SAC model are presented. Extensive experimental data of Henry’s law constants for CO2, N2 and O2 in ionic liquids at temperatures of 280-363 K are compared with numerical predictions to evaluate the accuracy of the COSMO-SAC model. It is found that Henry’s law constants for CO2 are predicted with an average relative deviation of 13%. Both numerical predictions and experimental data reveal that the solubility of carbon dioxide in ILs increases with an increase in the molar mass of ionic liquids, and is visibly more affected by the anion than by the cation. The calculations also show that the highest solubilities are obtained for [Tf2N]ˉ. Thus, the model can be regarded as a useful tool for the screening of ILs that offer the most favourable CO2 solubilities. The predictions of the COSMOSAC model for N2 and O2 in ILs differ from the pertinent experimental data. In its present form the COSMO-SAC model is not suitable for the estimation of N2 and O2 solubilities in ionic liquids.
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