High resoln. (-μm£ etching of semiconductors has been achieved by applying the scanning electrochem. microscope (SECM) in the feedback mode. Strong oxidants, such as bromine, were electrogenerated in situ at an ultramicroelectrode UME and the surface. The variables that affect the size and shape of the etched pattern, the required properties of the redox couple, and the mechanism of the etching process are discussed. This approach was successfully applied to several III-V and II-V semiconductors: gallium arsenide, gallium phosphide, cadmium telluride, and mercury cadmium telluride. . [on SciFinder(R)]
A scanning electrochem. microscope (SECM) was used as an anal. tool to study the etching of GaAs surfaces. Hole injection from several electrogenerated oxidants to n-type, p-type, and undoped GaAs was examd. by the feedback mode of the SECM. Assignment of the process as a hole injection from the oxidized form of the redox couple into the valence band and assignment of the energy of the valence band edge in the semiconductor were made by studying the behavior of the feedback current at various pHs and with different redox couples. The nature of the dopant strongly affected the etching process. Both n-GaAs and undoped GaAs were etched by using the feedback mode while p-GaAs was completely resistive toward etching. The differences between n-GaAs and p-GaAs are explained in terms of semiconductor-electrolyte interactions. [on SciFinder(R)]
The phase transfer catalyzed ethylation of deoxybenzoin has been studied in several solvents, using sym. quaternary ammonium bromides as catalysts. In all cases the reactivity passed through a max. as the size of the catalyst increased. The catalysts also reduce the interfacial tension between the phases; this effect also passing through a max. as a function of catalyst size. A correlation was obsd. between the two parameters, such that those catalysts reducing interfacial tension most markedly were also the best catalysts. Therefore, interfacial tension can be a guide to catalytic activity in certain PTC systems. [on SciFinder(R)]
We have recently identified and characterized a 53-kDa inner nuclear membrane-associated protein in Drosophila and termed it otefin. Here we report the isolation and characterization of cDNA and genomic clones of the otefin gene. Based on sequence analysis, we deduced that the primary translation product has a calculated mass of 45 kDa, contains many serine and threonine residues, and is mostly hydrophilic. However, in the carboxyl terminus, there is a hydrophobic region which may serve as a membrane anchoring domain. RNA blot analysis indicated that the otefin gene codes for a single poly(A+) transcript of 1.6 kilobases and that relatively large amounts of this transcript are present during developmental stages in which many nuclear divisions occur. Polyclonal antibodies raised against the cDNA translation product react with a 58-kDa mammalian nuclear envelope protein, demonstrating evolutionary conservation.
Southern blots of genomic DNA from a variety of species digested by restriction endonucleases having a four-bp specificity, were probed with a bovine genomic clone consisting of seven tandem poly-TG stretches separated by a 29bp linker sequence. Highly variable DNA 'fingerprint' patterns were obtained in chicken, sheep, and horse, moderately variable DNA 'fingerprints' in mouse and man, and a monomorphic pattern in Drosophila. In chicken, horse and man a (TG)10 synthetic oligonucleotide probe gave results identical to those given by the bovine probe. Furthermore, in chicken the DNA fingerprint variation showed typical Mendelian inheritance and differed from the fingerprints obtained with Jeffreys 33.6 and M13 minisatellite probes. Thus, for a variety of vertebrate species, poly-TG-containing probes can uncover useful genetic variation.
In the following pages, I wish to scan a neglected, if familiar, construction of Coptic for some of its most striking formal and functional, paradigmatic and syntagmatic aspects of significance nd implications. I refer to the construction sometimes called the “tautological”, “absolute”, or paronomastic infinitive, in which an infinitive is followed by a homolexemic (or otherwise related) finite verbal form, the two constituting together a single clause pattern: […]
Opaque contact lenses capable of imparting an apparent color modification to the wearer's iris comprises a polymer lens body and solid latex polymer particles directly bound to at least a portion of a surface of the lens. The invention method does not need for turbidity agent and binding polymer. A fully soaked lens was mounted on the index table of a transfer-pad printer and left to allow a portion of the water to evap. from the lens; an ink block contg. 40% ink and 60% HA-24 (latex from Rohm and Hass) was used for tinting the contact lens; after imprinting, the lenses are placed in an oven for 30-45 min at 80-95°. A schematic illustration of the tinting setup is given. [on SciFinder(R)]
A complete nucleotide sequence of a 4.2-kb genomic fragment containing the Drosophila lamin gene and flanking sequences is presented. Primer extension experiments and sequence analysis revealed that transcription starts from a single promoter. The lamin maternal 2.8-kb transcript and the 3.0-kb zygotic transcript are generated from two alternative polyadenylation sites. The gene contains four exons. The first intron is 7 bp upstream of the first AUG site. The two other introns are located within the alpha-helical rod domain of the protein: one in coil 1B in the 42-amino-acid domain that is absent in vertebrate cytoplasmic intermediate filament proteins and the other in coil 2 at a position different from intron positions within the vertebrate intermediate filament genes. Together with the sequence homology analysis, the data suggest either that the lamin gene was the ancestral gene of intermediate filament genes or that the lamin gene diverged from other intermediate filament genes early in evolution.
