1,813 research outputs found
Preparation of a chelating sorbent based on pyridylethylated polyethylenimine for recovering transition metal ions
A method was developed for preparing a chelating amino polymer, pyridylethylpolyethylenimine with maximal degree of substitution, by polymer-analogous transformations of branched polyethylenimine in reaction with 2-vinylpyridine. The ability of cross-linked pyridylethylpolyethylenimine with the degree of substitution of 0.32 to sorb Cu2+, Ni2+, Co2+, Zn2+, Cd2+, Mn2+, and Pb 2+ ions present simultaneously in solution was evaluated. In an ammonium acetate sorption system (pH 3.5-4.0), the sorbent selectively interacts with Cu(II) ions. © 2013 Pleiades Publishing, Ltd
Synthesis in a gel and sorption properties of N-2-sulfoethyl chitosan
A new procedure was developed for preparation of chelate amino-containing polymer N-2-sulfoethyl chitosan by synthesis in a gel through the reaction between chitosan and sodium 2-bromoethanesulfonate, yielding a polymer with the degree of substitution of up to 0.5. The structure of the resulting polymers was confirmed by 1H NMR spectroscopy. The sorption characteristics with respect to transition and alkaline-earth metal ions were determined for the cross-linked polymers. © 2013 Pleiades Publishing, Ltd
Generic representations of abelian groups and extreme amenability
If is a Polish group and is a countable group, denote by
\Hom(\Gamma, G) the space of all homomorphisms . We study
properties of the group \cl{\pi(\Gamma)} for the generic \pi \in
\Hom(\Gamma, G), when is abelian and is one of the following
three groups: the unitary group of an infinite-dimensional Hilbert space, the
automorphism group of a standard probability space, and the isometry group of
the Urysohn metric space. Under mild assumptions on , we prove that in
the first case, there is (up to isomorphism of topological groups) a unique
generic \cl{\pi(\Gamma)}; in the other two, we show that the generic
\cl{\pi(\Gamma)} is extremely amenable. We also show that if is
torsion-free, the centralizer of the generic is as small as possible,
extending a result of King from ergodic theory.Comment: Version
Tracking molecular wave packets in cesium dimers by coherent Raman scattering
We explore wave-packet dynamics in the ground X 1Σ+g and excited B 1Πu states
of cesium dimers (Cs2). In particular, we study the dependence of the wave-
packet dynamics on the relative timing between femtosecond pump, Stokes, and
probe pulses in a nondegenerate BOXCARS beam geometry, which are commonly used
for coherent anti-Stokes Raman scattering (CARS) spectroscopy. The
experimental results are elucidated by theoretical calculations, which are
based on the Liouville equations for the density matrix for the molecular
states. We observe oscillations in CARS signals as functions of both Stokes
and probe pulse delays with respect to the pump pulse. The oscillation period
relates to the wave-packet motion cycle in either the ground or excited state
of Cs2 molecules, depending on the sequence of the input laser pulses in time.
The performed analysis can be applied to study and/or manipulate wave-packet
dynamics in a variety of molecules. It also provides an excellent test
platform for theoretical models of molecular systems
Measurement of the cross section with the CMD-3 detector at the VEPP-2000 collider
The process has been studied in the
center-of-mass energy range from 1500 to 2000\,MeV using a data sample of 23
pb collected with the CMD-3 detector at the VEPP-2000 collider.
Using about 24000 selected events, the cross
section has been measured with a systematic uncertainty decreasing from 11.7\%
at 1500-1600\,MeV to 6.1\% above 1800\,MeV. A preliminary study of
production dynamics has been performed
Study of the process in the c.m. energy range from threshold to 2 GeV with the CMD-3 detector
Using a data sample of 6.8 pb collected with the CMD-3 detector at the
VEPP-2000 collider we select about 2700 events of the process and measure its cross section at 12 energy ponts with about
6\% systematic uncertainty. From the angular distribution of produced nucleons
we obtain the ratio
Coherent information analysis of quantum channels in simple quantum systems
The coherent information concept is used to analyze a variety of simple
quantum systems. Coherent information was calculated for the information decay
in a two-level atom in the presence of an external resonant field, for the
information exchange between two coupled two-level atoms, and for the
information transfer from a two-level atom to another atom and to a photon
field. The coherent information is shown to be equal to zero for all
full-measurement procedures, but it completely retains its original value for
quantum duplication. Transmission of information from one open subsystem to
another one in the entire closed system is analyzed to learn quantum
information about the forbidden atomic transition via a dipole active
transition of the same atom. It is argued that coherent information can be used
effectively to quantify the information channels in physical systems where
quantum coherence plays an important role.Comment: 24 pages, 7 figs; Final versiob after minor changes, title changed;
to be published in Phys. Rev. A, September 200
Femtosecond wave-packet dynamics in cesium dimers studied through controlled stimulated emission
Article on femtosecond wave-packet dynamics in cesium dimers studied through controlled stimulated emission
DYNAMICS OF SORPTION OF METAL IONS BY SULFOETHYLATED POLYALLYLAMINE WITH MODIFICATION DEGREE OF 1.6
In this work the sorption of silver (I) and copper (II) ions by crosslinked N-2-sulfoethylpolyallylamine with the degree of modification of 1.6 (SEPAA 1.6) was studied. Was calculated a dynamic exchange capacity of SEPAA 1.6. The values of dynamic exchange capacity were 11.4 μmol/g for silver (I) ions and 7.7 μmol/g for copper (II) ions.Исследование выполнено при финансовой поддержке РФФИ в рамках научного проекта № 16-33-00110 мол_а
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