709 research outputs found
Solvent Extraction of DNA with a Hydrolysable Double-chain Surfactant
A cationic lipophilic surfactant with two hydrolysable groups, di(1-octadecyloxycarbonylmethyl)dimethylammonium chloride, was synthesized and solvent extraction of deoxyribonucleotide (DNA) into organic solution (isooctane/1-octanol) with it as an extractant was examined. Not only a forward extraction of DNA into the organic phase but also back extraction into the aqueous phase (pH9) at room temperature proceeded efficiently. The forward extraction is promoted by electrostatic interactions of the surfactant and DNA and the back extraction is exclusively caused by hydrolysis of the surfactant to a non-surfactant.ArticleSEPARATION SCIENCE AND TECHNOLOGY. 44(2):466-475 (2009)journal articl
Strong photo-absorption by a single quantum wire in waveguide-transmission spectroscopy
We measured the absorption spectrum of a single T-shaped, 14x6 nm
lateral-sized quantum wire embedded in an optical waveguide using
waveguide-transmission spectroscopy at 5 K. In spite of its small volume, the
one-dimensional-exciton ground state shows a large absorption coefficient of 80
/cm, or a 98 % absorption probability for a single pass of the 500-um-long
waveguide.Comment: 4 pages, 3 figure
Room-temperature excitonic absorption in quantum wires
We measured absorption spectra of T-shaped quantum wires at room temperature
using waveguide-transmission spectroscopy. Strong and narrow room-temperature
one-dimensional-exciton absorption peak was observed, which shows peak modal
absorption coefficient of 160 cm per 20 wires with -factor of
, width of 7.2 meV, and strong polarization anisotropy.Comment: 3pages, 3figure, 1tabl
Imaging of emission patterns in a T-shaped quantum wire laser
Spatially and spectrally resolved microscopic images of spontaneous and
stimulated emissions are imaged at the mirror facets of a GaAs T-shaped quantum
wire laser with high uniformity. Laser emission from the one-dimensional ground
state reveals a circular image located at the core of a T-shaped optical
waveguide but significantly smaller in area than the low power spontaneous
emission from the same waveguide. These images unambiguously allow assignment
of all spontaneous and laser emissions to the wire ground state and respective
intersecting wells in the structure.Comment: 4 pages, 3 figure
Quasi-Solitons in Dissipative Systems and Exactly Solvable Lattice Models
A system of first-order differential-difference equations with time lag
describes the formation of density waves, called as quasi-solitons for
dissipative systems in this paper. For co-moving density waves, the system
reduces to some exactly solvable lattice models. We construct a shock-wave
solution as well as one-quasi-soliton solution, and argue that there are
pseudo-conserved quantities which characterize the formation of the co-moving
waves. The simplest non-trivial one is given to discuss the presence of a
cascade phenomena in relaxation process toward the pattern formation.Comment: REVTeX, 4 pages, 1 figur
Measurement of methane flux over an evergreen coniferous forest canopy using a relaxed eddy accumulation system with tuneable diode laser spectroscopy detection
Very few studies have conducted long-term observations of methane (CH4) flux over forest canopies. In this study, we continuously measured CH4 fluxes over an evergreen coniferous (Japanese cypress) forest canopy throughout 1 year, using a micrometeorological relaxed eddy accumulation (REA) system with tuneable diode laser spectroscopy (TDLS) detection. The Japanese cypress forest, which is a common forest type in warm-temperate Asian monsoon regions with a wet summer, switched seasonally between a sink and source of CH4 probably because of competition by methanogens and methanotrophs, which are both influenced by soil conditions (e.g., soil temperature and soil moisture). At hourly to daily timescales, the CH4 fluxes were sensitive to rainfall, probably because CH4 emission increased and/or absorption decreased during and after rainfall. The observed canopy-scale fluxes showed complex behaviours beyond those expected from previous plot-scale measurements and the CH4 fluxes changed from sink to source and vice versa
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