Symmetry of single chain DNA molecules

A system of "colour" transformations of symmetry is introduced on the basis of which all possible symmetry groups of the single-chain DNA molecule taken in the form of a genetic text are derived. A strict theoretical group description of such functionally important symmetrical structures as a palindrome, complementary palindrome and direct repeat is given and their possible role in the genome discussed. © 1993

Study of the bufadienolides of the skin secretion of green toads (Bufo viridis Laur, 1758)

The composition of the skin secretion of Bufo viridis toads, which inhabit the Kharkov region, has been studied in this work

Femtosecond coherent spectroscopy of four-wave mixing and photon echoes in a GaAs/AlGaAs heterostructure at room temperature

The results from experiments employing coherent femtosecond spectroscopy in a layer of two-dimensional electron gas at the boundary of the GaAs/AlGaAs heterojunction at room temperature are presented. The decay curves of primary femtosecond photon echo are obtained. The decoherence time in two-dimensional electron gas depends strongly on the power of the exciting pulse and varies from 36 to 54 fs. The dephasing time is studied for the first time as a function of the power of exciting pulses at room temperature. It is established that this dependence obeys the law T 2 ∼ N -0.22, which differs from the typical law T 2 ∼ N -1 for unscreened electron-electron interaction in semiconductor crystals. Analysis shows that electron-phonon interaction plays an important part along with electron-electron interaction. The induced spin gratings in the GaAs/AlGaAs heterostructure are studied with an eye to their possible application in spintronics. © Allerton Press, Inc., 2012

Synthesis, transport, and ionophore properties of α,ω- biphosphorylated azapodands: VIII. Solvent extraction of the metal ions with N,N′-bis(dioctylphosphorylmethyl)-1,8-diamino-3,6-dioxaoctane

Liquid extraction from the aqueous solutions of perchloric acid with neutral azapodand extractant N,N′-bis(dioctylphosphorylmethyl)-1,8- diamino-3,6-dioxaoctane has been highly efficient in the cases of uranyl ions and some metals of groups II and III. To estimate the synergic effect of organophosphorus extractants, the neutral extractant was applied in the mixture with an acidic component, bis(pentadecyl)phosphoric acid. The synergic effect has exclusively been observed in the extraction of zinc and cadmium ions. © 2013 Pleiades Publishing, Ltd

Extraction of scandium ions by new aminophosphinyl extractants

Extraction of Sc(III) ions by new aminophosphinyl compounds containing one or two methylenediorganylphosphinyl groups at the nitrogen atom was studied with a target of the development of effective and selective extractants of trace elements. The selection of extractants was due to their high hydrolytic stability in the acid media, commonly used at the extraction of metal ions in the industrial hydrometallurgical processes. The study of extraction of hydrogen chloride and nitric acids with the selected aminophosphinyl compounds allowed a discovery of substances with the low basicity, which were characterized by the low coefficient of the acids extraction. Highly effective extractants of Sc(III) were found possessing high coefficients of extraction and high degree of selectivity in the separation of Sc(III) ion from the ions of satellite metals. © Pleiades Publishing, Ltd., 2009

2.11. Necessary conditions for interpolation by entire functions

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41580/1/10958_2005_Article_BF01221572.pd

Toward a Theory of Experience

Science Education, Vol. 98, No. 1, pp. 106–126Experience is one of the most used terms in (science) education, and it is recognized as being related to learning (education). Yet what experience is and how it is related to learning and change remains untheorized. In this paper, we mainly draw on the work of J. Dewey and L. S. Vygotsky but also on M. Bakhtin and more recent advances on the topic of experience from French philosophy to contribute to a theory of this important category. Accordingly, experience is not something that belongs to or is had by individuals but rather denotes transactions in and across space and time within irreducible person-in-setting units; and it is perfused with an affect that is not (only) the result of mental constructions. An episode from an Australian physics classroom is used to exemplify what such a theory and its method-related implications have to accomplish in the analysis of concrete science lessons

Understanding the role of objects in cross-disciplinary collaboration

In this paper we make a case for the use of multiple theoretical perspectives – theory on boundary objects, epistemic objects, cultural historical activity theory and objects as infrastructure - to understand the role of objects in cross-disciplinary collaboration. A pluralist approach highlights that objects perform at least three types of work in this context: they motivate collaboration; they allow participants to work across different types of boundaries; and they constitute the fundamental infrastructure of the activity. Building on the results of an empirical study we illustrate the insights that each theoretical lens affords into practices of collaboration and develop a novel analytical framework that organizes objects according to the active work they perform. Our framework can help shed new light on the phenomenon, especially with regards the shifting status of objects and sources of conflict (and change) in collaboration. After discussing these novel insights, we outline directions for future research stemming from a pluralist approach. We conclude by noting the managerial implications of our finding

A case study analysis of a constructionist knowledge building community with activity theory

This article investigates how activity theory can help research a constructionist community. We present a constructionist activity model called CONstructionism Through ACtivity Theory (CONTACT) model and explain how it can be used to analyse the constructionist activity in knowledge building communities. We then illustrate the model through its application to analysing the Wiki-supported community associated with a computer game. Our analysis focuses mainly on two perspectives: individual and collective actions, as well as individual and collective mediations. Experiences and challenges from the analysis are reported to demonstrate how CONTACT is helpful in analysing such communities