Influence of the epitaxial composition on N-face GaN KOH etch kinetics determined by ICP-OES.

Roughening by anisotropic etching of N-face gallium nitride is the key aspect in today's production of blue and white light emitting diodes (LEDs). Both surface area and number of surface angles are increased, facilitating light outcoupling from the LED chip. The structure of a GaN layer stack grown by metal organic chemical vapour deposition (MOCVD) was varied in the unintentionally doped u-GaN bulk region.

Expanding the limits of amide-triazole isosteric substitution in bisamide-based physical gels.

Gelation of organic solvents using ,'-((1,2)-cyclohexane-1,2-diyl)didodecanamide (C-Cyc) is driven by its self-assembly antiparallel hydrogen bonds and van der Waals intermolecular interactions. In this work we carried out a dual isosteric substitution of the two amide groups with 1,2,3-triazole rings affording the corresponding isosteric gelator (click-C-Cyc). A detailed comparative study in terms of the gelation ability and gel properties demonstrated that the 1,2,3-triazoles can take over all of the functions derived from the amide groups offering a versatile strategy for tuning the properties of the corresponding gels.

Isosteric Substitution of 4 H-1,2,4-Triazole by 1 H-1,2,3-Triazole in Isophthalic Derivative Enabled Hydrogel Formation for Controlled Drug Delivery.

In this work, we demonstrated that the simple substitution of the 1,2,4-triazole moiety in 5-( 4H-1,2,4-triazol-4-yl)isophthalic acid (5-TIA) by the 1 H-1,2,3-triazol-5-yl unit enables the preparation of a hydrogelator (click-TIA). In sharp contrast to 5-TIA, its isostere click-TIA undergoes self-assembly in water upon sonication, leading to the formation of stable supramolecular viscoelastic hydrogels with a critical gelation concentration of 6 g/L. Hydrogels made of click-TIA as well as hybrid hydrogels made of the mixture click-TIA + 5-TIA (molar ratio 1:0.

[Radiation exposure from nuclear medical procedures in the former DDR].

From 1978-1988 central records were kept of nuclear medical in vivo and in vitro examinations and of treatments with radiopharmaceuticals in the former GDR. On the basis of ICRP publications No 60 the effective dose, the collective effective dose, and the radiation risk were assessed. Twenty-six different nuclear medical examinations were used in the calculations.

Radiopharmacokinetics and radiation absorbed dose calculations from 131I-meta-iodobenzylguanidine (131I-MIBG).

In connection with clinical 131I-MIBG studies of patients with suspected pheochromocytoma and adrenomedullary hyperplasia quantitative biokinetic data have been collected in order to improve the present estimations of absorbed dose to various organs and tissues. Whole-body profiles as a function of time were measured with a whole-body counter. The retention in the total body and in the thyroid gland could be derived from the measured whole-body profiles by summing up the corresponding values.

Radiopharmacokinetics and radiation dose from 99mTc-HM-PAO (preliminary report).

Whole body retention measurements were performed in volunteers after i.v. injection of 99mTc-HM-PAO (Ceretec).

Radiation dose and risk of patients through nuclear medical procedures in the GDR. A comparison of 1978 and 1981.

For the years 1978 and 1981 we compared the radiation dose for the patients examined by in vivo methods after administration of radiopharmaceuticals (27 procedures). The somatic effective dose equivalent, the effective collective dose, the somatic radiation risk, and the number of induced malignancies were calculated according to ICRP publication No. 26.