2,081 research outputs found
Cytochemical and histochemical characterization of cotyledonary bodies from Pharbitis nil seedlings
Cytological
and
histochemical
characterization
of
the
structures
from
which
an
obscure
substance
is
secreted
via
open
stomata
to
the
abaxial
surface
of
Japanese
morning
glory
(Pharbitis
nil
Choisy
cv.
Violet)
cotyledons
has
been
carried
out.
Observation
of
intact
cotyledons
using
the
light
microscope
revealed
randomly
distributed
semi-transparent
structures.
These
structures,
which
were
shown
to
be
the
same
as
those
previously
described
as
giant
oil
cells
are
referred
to
here
as
cotyledonary
bodies.
These
bodies
can
be
eas-
ily
isolated
and
purified
after
enzymatic
digestion
of
the
cotyledons.
Using
different
staining
procedures
we
have
confirmed
that
each
cotyledonary
body
originates
from
an
individual
mesophyll
cell
dur-
ing
embryo
development.
Purified
bodies
consist
of
(i)
a
thick
shell-
like
envelope;
(ii)
a
transparent,
hydrophilic
zone;
(iii)
a
hydropho-
bic
core.
Hydrophobic
contents
of
the
bodies
were
readily
extracted
with
methanol
and
shown
to
contain
fatty
acids
and
phenolic
com-
pounds
using
the
gas
chromatography/mass
spectrometry
(GC/MS)
technique.
Methanolic
extracts
of
cotyledonary
bodies
showed
high
fluorescence
with
two
excitation
and
emission
maxima.
Using
a
flu-
orescence
microscope
we
have
shown
that
the
bodies
isolated
from
seedlings
grown
in
continuous
light,
conditions
non-inductive
for
flowering,
and
those
grown
under
conditions
inductive
for
flowering
(a
single
16
h,
long
dark
period)
have
different
fluorescence
emis-
sion
spectra.
Different
levels
of
free
Ca
2+
inside
cotyledonary
bodies
isolated
from
light-grown
and
single
dark-period
treated
P.
nil
seed-
lings
were
found
using
the
fluorescent
calcium
indicator
dye
Fluo-3
under
a
confocal
scanning
laser
microscope.
On
the
basis
of
these
observations
we
speculate
that
cotyledonary
bodies
could
be
in-
volved
in
floral
induction
A Mini-Orange Spectrometer for Internal Conversion Measurement in ISOL and In-Beam Experiments
開始ページ、終了ページ: 冊子体のページ付
25 kHz narrow spectral bandwidth of a wavelength tunable diode laser with a short waveguide-based external cavity
We report on the spectral properties of a diode laser with a tunable external
cavity in integrated optics. Even though the external cavity is short compared
to other small-bandwidth external cavity lasers, the spectral bandwidth of this
tunable laser is as small as 25 kHz (FWHM), at a side-mode suppression ratio
(SMSR) of 50 dB. Our laser is also able to access preset wavelengths in as
little as 200 us and able to tune over the full telecom C-band (1530 nm - 1565
nm).Comment: 8 pages, 7 figure
High-pressure neutron study of the morphotropic PZT: phase transitions in a two-phase system
In piezoelectric ceramics the changes in the phase stabilities versus stress
and temperature in the vicinity of the phase boundary play a central role. The
present study was dedicated to the classical piezoelectric,
lead-zirconate-titanate (PZT) ceramic with composition
Pb(ZrTi)O at the Zr-rich side of the morphotropic phase
boundary at which both intrinsic and extrinsic contributions to
piezoelectricity are significant. The pressure-induced changes in this
two-phase (rhombohedral +monoclinic at room temperature and
above 1 GPa pressures) system were studied by high-pressure neutron
powder diffraction technique. The experiments show that applying pressure
favors the phase, whereas the phase transforms continuously to the
, which is favored at elevated temperatures due to the competing entropy
term. The phase transformation is discontinuous. The
transformation contributes to the extrinsic piezoelectricity. An important
contribution to the intrinsic piezoelectricity was revealed: a large
displacement of the cations (Zr and Ti) with respect to the oxygen anions
is induced by pressure. Above 600 K a phase transition to a cubic phase took
place. Balance between the competing terms dictates the curvature of the phase
boundary. After high-pressure experiments the amount of rhombohedral phase was
larger than initially, suggesting that on the Zr-rich side of the phase
boundary the monoclinic phase is metastable.Comment: 6 figure
Calibration of the Isomer Shift for the 35.46 keV Mossbauer Transition of 125Te
開始ページ、終了ページ: 冊子体のページ付
Reduction of the Neutron-Induced r-Ray Background in an ISOL Experiment by Making Use of a Beam Chopper
開始ページ、終了ページ: 冊子体のページ付
Standard and Embedded Solitons in Nematic Optical Fibers
A model for a non-Kerr cylindrical nematic fiber is presented. We use the
multiple scales method to show the possibility of constructing different kinds
of wavepackets of transverse magnetic (TM) modes propagating through the fiber.
This procedure allows us to generate different hierarchies of nonlinear partial
differential equations (PDEs) which describe the propagation of optical pulses
along the fiber. We go beyond the usual weakly nonlinear limit of a Kerr medium
and derive an extended Nonlinear Schrodinger equation (eNLS) with a third order
derivative nonlinearity, governing the dynamics for the amplitude of the
wavepacket. In this derivation the dispersion, self-focussing and diffraction
in the nematic are taken into account. Although the resulting nonlinear
may be reduced to the modified Korteweg de Vries equation (mKdV), it also has
additional complex solutions which include two-parameter families of bright and
dark complex solitons. We show analytically that under certain conditions, the
bright solitons are actually double embedded solitons. We explain why these
solitons do not radiate at all, even though their wavenumbers are contained in
the linear spectrum of the system. Finally, we close the paper by making
comments on the advantages as well as the limitations of our approach, and on
further generalizations of the model and method presented.Comment: "Physical Review E, in press
Three-dimensional flux states as a model for the pseudogap phase of transition metal oxides
We propose that the pseudogap state observed in the transition metal oxides
can be explained by a three-dimensional flux state, which exhibits
spontaneously generated currents in its ground state due to electron-electron
correlations. We compare the energy of the flux state to other classes of mean
field states, and find that it is stabilized over a wide range of and
. The signature of the state will be peaks in the neutron diffraction
spectra, the location and intensity of which are presented. The dependence of
the pseudogap in the optical conductivity is calculated based on the parameters
in the model.Comment: submitted to Phys. Rev. B on January 8, 200
- …