Genetic relationships among some Hesperis L. (Brassicaceae) species from Turkey assessed by RAPD analysis

In this study the phylogenetic relations among infraspecific, specific and supraspecific categories of 6 taxa of the genus Hesperis collected from different parts of Turkey were investigated by RAPD analysis.The results of the RAPD analysis support the idea that H. bicuspidata (Sect. Hesperis), H. schischkinii (Sect. Mediterranea), H. pendula (Sect. Pachycarpos), H. breviscapa, H. kotschyi (Sect. Cvelevia) and H.cappadocica (Sect. Contorta) species need to be placed into different sections according to morphological characters. On the other hand, the phylogenetic order of the sections according to morphological characters and according to molecular data displayed some differences and evolutionary phylogenetic orders of the sections were redesigned. The phylogenetic relations among species were based on the samples H. breviscapa and H. kotschyi which take place in the same section.The accordance of morphological and molecular similarities was noticed for H. breviscapa and H. kotschyi species. Besides this, infraspecific taxonomic situations of H. schischkinii samples havinghairy and glabrous (non-hairy) fruits which show allopatric and sympatric spread were reassessed by RAPD analysis

Self-Aligned Ballistic Molecular Transistors and Electrically Parallel Nanotube Arrays

Carbon nanotube field-effect transistors with structures and properties near the scaling limit with short (down to 50 nm) channels, self aligned geometries, palladium electrodes with low contact resistance and high-k dielectric gate insulators are realized. Electrical transport in these miniature transistors is near ballistic up to high biases at both room and low temperatures. Atomic layer deposited (ALD) high-k films interact with nanotube sidewalls via van der Waals interactions without causing weak localization at 4 K. New fundamental understanding of ballistic transport, optical phonon scattering and potential interfacial scattering mechanisms in nanotubes are obtained.Comment: Nano Letters, in pres

Ultra-High Yield Growth of Vertical Single-Walled Carbon Nanotubes: Hidden Roles of Hydrogen and Oxygen

An oxygen assisted hydrocarbon chemical vapor deposition (CVD) method is developed to afford large-scale highly reproducible ultra high-yield growth of vertical single-walled carbon nanotubes (SWNT). It is revealed that reactive hydrogen (H)-species, inevitable in hydrocarbon-based growth, are damaging to the formation of sp2-like SWNTs. The addition of oxygen scavenges H-species and provides a powerful control over the C/H ratio to favor SWNT growth. The revelation of the roles played by hydrogen and oxygen leads to a unified and universal optimum growth condition for SWNTs. Further, a versatile method is developed to form vertical SWNT films on any substrate, lifting a major substrate-type limitation for aligned SWNTs.Comment: 14 pages of text and 6 figure

Early Geometrical Thinking in the Environment of Patterns, Mosaics and Isometries

This book discusses the learning and teaching of geometry, with a special focus on kindergarten and primary education. It examines important new trends and developments in research and practice, and emphasizes theoretical, empirical and developmental issues. Further, it discusses various topics, including curriculum studies and implementation, spatial abilities and geometric reasoning, as well as the psychological roots of geometrical thinking and teacher preparation in geometry education. It considers these issues from historical, epistemological, cognitive semiotic and educational points of view in the context of students' difficulties and the design of teaching and curricula