Próby uprawy Citrullus colocynthis (L.) Schrad. i wstępna ocena przydatności nasion [An attempt at Citrullus colocynthis (L.) Schrad. cultivation and the initial estimation of the seeds utility]

Trials of cultivating Citrullus colocynthis (L.) Schrad. were carried out in the Medicinal Plant Garden of the Medical Academy to Wrocław. The seeds were obtained from Bucarest and stored for one year. The plants obtained from those seeds developed well, produced flowers and fruited. The seeds germinated in darknees in about 90%. Light distinctly inhibited germination. Urease activity was determinated initially in the seeds by the method of Sumner. One kilogram of whole seeds has an activity of about 12000 Summer units

Próby uprawy Citrullus colocynthis (L.) Schrad. i wstępna ocena przydatności nasion [An attempt at Citrullus colocynthis (L.) Schrad. cultivation and the initial estimation of the seeds utility]

Trials of cultivating Citrullus colocynthis (L.) Schrad. were carried out in the Medicinal Plant Garden of the Medical Academy to Wrocław. The seeds were obtained from Bucarest and stored for one year. The plants obtained from those seeds developed well, produced flowers and fruited. The seeds germinated in darknees in about 90%. Light distinctly inhibited germination. Urease activity was determinated initially in the seeds by the method of Sumner. One kilogram of whole seeds has an activity of about 12000 Summer units

Changes to the Triaxial Composition of the Hydrated Phases (CaO/Al2O3/SiO2) in the Metakaolin/Lime System

This study examines the composition of certain hydrates (calcium silicate, aluminum silicate, and related phases) produced by the pozzolanic reaction of waste-paper sludge that had previously been activated at different temperatures. It summarizes and compares the evolution of the oxide compounds, and records their stability intervals. Changes to their mineralogical composition were analyzed using X-Ray Diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy. The hydration products from 1 to 360 days of curing time were CSH gels, hydrotalcite-type compounds (LDH), and stratlingite (C2ASH8). CSH gels were employed as substrates for growing other materials and their morphologies were modified from fibrous to hexagonal layers. The composition of the LDH-type compounds observed in the carbonate group varied with changes in curing time. Two LDH-type compound types were identified: (a) with and (b) without magnesium. Stratlingite was the only stable material after long-curing times.Peer reviewe

Polarization-reduced quaternary InAlGaN/GaN HFET and MISHFET devices

The reduction of the polarization charge in a GaN-based single-heterostructure field-effect transistor (HFET) by polarization engineering is proposed as a method for achieving normally off operation. The concept minimizes the dependence of the threshold voltage on the barrier layer thickness. Therefore, thicker gate dielectrics for suppression of gate leakage currents can be applied without a shift in threshold voltage. A polarization-reduced enhancement-mode (E-mode) InAlGaN/GaN HFET is presented and demonstrates the basic working principle. Also an insulated-gate device with only minor shift in threshold voltage compared to the HFET validates the new concept and demonstrates the advantages compared to commonly applied concepts for E-mode operation

Analysis of metal surfaces coated with europium-doped titanium dioxide by laser induced breakdown spectroscopy

The surface passivation with titanium sol-gel coatings is a frequently used technique to control the adsorption of selected biological macromolecules and to reduce the exposure of the bulk material to biological matter. Due to the increasing number of new coating-preparation methods and new gel compositions with various types of additives, the quality and homogeneity determination of the surface covering is a critical factor affecting performance of any implanted material. While coating thickness is easy to determine, the homogeneity of the surface distribution of coating materials requires more elaborate methodologies. In the paper, the laser induced breakdown spectroscopy (LIBS) based method, capable to quantitate the homogeneity and uniformity of the europium in titanium dioxide sol-gel coatings on stainless steel surfaces prepared with two different procedures: spin-coating and dip-coating, is presented. The emission intensity of titanium has been used to determine the coating thickness whereas the relative values of europium and titanium emission intensities provide data on the coating homogeneity. The obtained results show that the spin-coating technique provides better surface coverage with titanium dioxide. However, when the surface coating compositions were compared the dip-coating technique was more reliable

Ultrastructure of oogenesis in two oviparous demosponges: Axinella damicornis and Raspaciona aculeata

15 páginas, 12 figuras.We investigated the cytology of the oogenic cycle in two oviparous demosponges, Axinella damicornis and Raspaciona aculeata, during 2 consecutive years both by light and electron microscopy. Oocytes of both species were similar in their basic morphological features but differences were noticed in time required to complete oocyte maturation and mechanisms of acquisition of nutritional reserves. The oogenic cycle of A. damicornis extended for 7–8 months in autumn-spring, while that of R. aculeata did it for 3–5 months in summer-autumn. Yolk of A. damicornis was predominantly formed by autosynthesis. Oocytes endocytosed bacteria individually and stored them in groups in large vesicles. Bacteria were digested and lipidic material was added to the vesicles to produce a peculiar granular yolk hitherto unknown in sponges. Scarce cells carrying heterogeneous inclusions were observed in the perioocytic space, and were interpreted as putative nurse cells. Such cells were presumably releasing lipid granules to the perioocytic space. In contrast, large numbers of nurse cells were found surrounding the oocytes of R. aculeata. They transported both lipid granules and heterogeneous yolk bodies to the oocytes. R. aculeata also produced some of their yolk by autosynthesis. The involvement of nurse cells in the vitellogenesis of R. aculeata shortened the oocyte maturation, whereas a largely autosynthetic vitellogenesis in A. damicornis prolonged the duration of oogenesis.This study was supported by two grants from the Spanish Ministry for Science and Education (MCYT-BMC2002-01228; MEC-CTM2005-05366/MAR).Peer reviewe