Processing of Boron Carbide-Aluminum Composites

The processing problems associated with boron carbide and the limitations of its mechanical properties can be significantly reduced when a metal phase (e.g., aluminum) is added. Lower densification temperatures and higher fracture toughness will result. Based on fundamental capillarity ther modynamics, reaction thermodynamics, and densification kinetics, we have established reliable criteria for fabricating B₄C–Al particulate composites. Because chemical reactions cannot be eliminated, it is necessary to process B₄C–AI by rapidly heating to near 1200°C (to ensure wetting) and subsequently heat-treating below 1200°C (for microstructural development).     

Some fundamental properties of second-order active RC filters with composite operational amplifiers

Second-order active RC filters employing N identical operational amplifiers (OAs) are considered. the way to achieve the highest-order zero sensitivities of the dominant poles is shown. It leads to composite operational amplifiers (COAs) with a gain function of a polynomial form. the analysis of sensitivities, errors and location shifts of dominant poles as well as the effects of parasitic poles is also provided. the results have been confirmed by numerical analysis and an experimental verification.     

PEO Coatings Modified with Halloysite Nanotubes: Composition,Properties, and Release Performance

In this work, the properties of the coatings formed on the Mg-Mn-Ce alloy by plasma electrolytic oxidation (PEO) in electrolytes containing halloysite nanotubes (HNTs) were investigated. The incorporation of halloysite nanotubes into the PEO coatings improved their mechanical characteristics, increased thickness, and corrosion resistance. The studied layers reduced corrosion current density by more than two times in comparison with the base PEO layer without HNTs (from 1.1 × 10⁻⁷ A/cm² to 4.9 × 10⁻⁸ A/cm²). The presence of halloysite nanotubes and products of their dihydroxylation that were formed under the PEO conditions had a positive impact on the microhardness of the obtained layers (this parameter increased from 4.5 ± 0.4 GPa to 7.3 ± 0.5 GPa). In comparison with the base PEO layer, coatings containing halloysite nanotubes exhibited sustained release and higher adsorption capacity regarding caffeine.     

Palmoplantar Keratoderma: A Molecular Genetic Analysis of Family Cases

Palmoplantar keratoderma is a clinically polymorphic disorder with a heterogeneous etiology characterized by marked hyperkeratotic lesions on the surface of palms and soles. Hereditary forms of palmoplantar keratoderma usually have autosomal dominant inheritance and are caused by mutations in dozens of genes, most of which belong to the keratin family. We carried out clinical and molecular genetic analysis of the affected and healthy members of four families with autosomal dominant palmoplantar keratoderma. In three out of four family cases of autosomal dominant palmoplantar keratoderma, the following molecular genetic causes were established: in two families—previously non-described missense mutations in the AQP5 gene ({"type":"entrez-nucleotide","attrs":{"text":"NM_001651.4","term_id":"1519473780","term_text":"NM_001651.4"}}NM_001651.4): c.369C>G (p.(Asn123Lys)) and c.103T>G (p.(Trp35Gly)); in one family—a described splice site mutation in the KRT9 gene ({"type":"entrez-nucleotide","attrs":{"text":"NM_000226.4","term_id":"1519245988","term_text":"NM_000226.4"}}NM_000226.4): c.31T>G. In one family, the possible cause of palmoplantar keratoderma was detected—a variant in the KRT1 gene ({"type":"entrez-nucleotide","attrs":{"text":"NM_006121.4","term_id":"1519311739","term_text":"NM_006121.4"}}NM_006121.4): c.931G>A (p.(Glu311Lys)).     

Pattern learning in humans and electronic learning nets

The letter reports on a previously unseen similarity between an associative memory model recently proposed for the brain and some electronic systems that have been developed for practical learning machines. This similarity is analysed, and its implications are discussed. Results of a comparison between the learning behaviour of an electronic network and a group of human subjects in a pattern-recognition task are given to complete the comparative study.     

Spatial distributions of residuals produced inside a spallation target

The spallation target model of an accelerator driven system (ADS), consisting of six 5 cm thick and 16 cm in diameter Pb segments, was constructed. Three sets of 17 Bi samples (1/2 inch in diameter and 1 mm thick) were placed in 3 Pb disc-shaped holders inside the target at 5, 10 and 15 cm from its front. After irradiation with 660 MeV proton beam gamma-spectra of radioisotopes produced in Bi were collected several times for each sample with the use of HPGe detectors in order to identify the radioisotopes and to determine their absolute activities. Their spatial distributions were then compared with respective values obtained in the calculations made with the use of FLUKA and/or MCNPX code. A fair agreement with the experiment has been observed.     

Untersuchungen über den Kohlenmonoxydzerfall und seine katalytische Vergiftung

Untersuchung über den Einfluß von Schwefelwasserstoffzusätzen zu Kohlenmonoxyd und gichtgasähnlichen Gasgemischen auf den Kohlenmonoxydzerfall an Gichtstaub und reinem Eisen(III)-oxyd. Erörterung der Analysenverfahren. Diskontinuierliche Vergiftungsversuche. Betriebsversuche an kleinen Rekuperatoren. Versuche an feuerfesten Steinen.