Degenerate polynomial patches of degree 11 for almostGC 2 interpolation over triangles

We consider the problem of interpolating scattered data in ³ by analmost geometrically smoothGC ² surface, where almostGC ² meansGC ² except in a finite number of points (the vertices), where the surface isGC ¹. A local method is proposed, based on employing so-called degenerate triangular Bernstein-Bézier patches. We give an analysis of quintic patches forGC ¹ and patches of degree eleven for almostGC ² interpolation.     

Computer controlled spreading resistance system for measurement of carrier concentration profiles of silicon structures

A new computer controlled equipment for carrier concentration profile determination of silicon structures by a spreading resistance technique is presented. The required data and plots can easily be obtained by means of a new software package, which has been specially developed for this purpose. Measurements have been performed on different structures in order to verify the suitability of both the measuring system and the software package. The reproducibility has been found to be within 5% for the investigated structures.     

7-Deazaadenosine: Oligoribonucleotide building block synthesis and autocatalytic hydrolysis of base-modified hammerhead ribozymes

A 7-deazaadenosine ( = tubercidin; c⁷A; 1 ) building block for solid-phase oligoribonucleotide synthesis was prepared. The amino group of 1 was protected with the (dimethylamino)methylidene residue (→ 3 ), and the monomethoxytrityl group was introduced at OH? C(5′) (→ 4 ). Protection of OH? C(2′) was carried out by silylation, showing that use of the (i-Pr)₃Si group resulted in high 2′-O-selectivity (→ 5b , 80%). Reaction of 5b with PCl₃ afforded the phosphonate 7 which was used in solid-phase oligoribonucleotide synthesis. The autocatalytic hydrolysis of hammerhead ribozymes using pG-G-G-A-G-U-C-A-G-U-C-C-C-U-U-C-G-G-G-G-A-C-U-C-U-G-A-A-G-A-G-G-C-G-C as substrate strand (S) and modified G-C-G-C-C-G-A-A-A-C-U-C-C-C as enzyme strand (E) was studied. When c⁷A replaced A¹³ or A¹⁴, a small decrease of catalytic activity was observed, while modification in position A¹⁵ enhanced the autocatalytic hydrolysis. The results demonstrate, that the atom N(7) of adenosine in any of these positions is not crucial for ribozyme action.     

Ferrocene studies. IV. Some furan containing derivatives of ferrocene

The condensation of ferrocenecarboxyhydrazide, ferrocenecarboxaldehyde and acetylferrocene with a number of furan derivatives is reported. The reaction of chalcones containing both the furan and the ferrocene nucleus with Phenylhydrazine and hydrazine proceeds to yield pyrazolines.