507 research outputs found
ElectronâDiffraction Study of Ammonia and Deuteroammonia
The gasâphase structures of NH3 and ND3 molecules were determined by the sectorâmicrophotometer method of electron diffraction. The following internuclear distances rgrg and mean amplitudes lele with estimated standard errors were obtained: For NH3, rg(NâââH)â = â1.0302â±â0.002Ă
,rg(HâââH)â = â1.662â±â0.010Ă
,le(NâââH)â = â0.0731â±â0.002Ă
,le(HâââH)â = â0.125â±â0.006Ă
rg(NâH)=1.0302±0.002Ă
,rg(HâH)=1.662±0.010Ă
,le(NâH)=0.0731±0.002Ă
,le(HâH)=0.125±0.006Ă
, and for ND3, rg(NâââD)â = â1.0266â±â0.003Ă
,rg(DâââD)â = â1.654â±â0.008Ă
,le(NâââD)â = â0.0611â±â0.002Ă
,le(DâââD)â = â0.101â±â0.006Ă
rg(NâD)=1.0266±0.003Ă
,rg(DâD)=1.654±0.008Ă
,le(NâD)=0.0611±0.002Ă
,le(DâD)=0.101±0.006Ă
, with the parameter ÎșÎș representing bondâstretching anharmonicity fixed at 1.0âĂâ10â5 and 0.5âĂâ10â5 Ă
3 for NâH and NâD, respectively. Effects of anharmonicity and isotope differences in the structural parameters analogous to those in CH4 and CD4 were observed. The rα0rα0 and rere bond distances calculated from the above rgrg distances are found to be consistent with the corresponding rzrz and rere distances derived from the spectroscopic rotational constants of Benedict and Plyler. The isotope effects reported by Bell and by Halevi for the dipole moment and polarizability of ammonia are discussed briefly in the light of the present results.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69943/2/JCPSA6-49-6-2488-1.pd
Photoemission study of poly(dA)-poly(dT) DNA : Experimental and theoretical approach to the electronic density of states
We present results of an ultraviolet photoemission spectroscopy study of
artificially synthesized poly(dA)-poly(dT) DNA molecules on -type Si
substrates. For comparison, we also present the electronic density of states
(DOS) calculated using an \emph{ab initio} tight-binding method based on
density-functional theory (DFT). Good agreement was obtained between experiment
and theory. The spectra of DNA networks on the Si substrate showed that the
Fermi level of the substrate is located in the middle of the band gap of DNA.
The spectra of thick ( nm) DNA films showed a downward shift of eV compared to the network samples.Comment: 4 pages, 4 figure
Change of proton gradient in mitochondria at various energy states
Changes of H+ gradient at various energy states of mitochondria were studied. There was a close relation between the extent of H+ gradient and the level of ATP formation; the former decreased as a result of ATP
synthesis but was not completely abolished. A partial depression of H+ gradient was also observed in the presence of uncouplers of oxidative phosphorylation. The H+ gradient seemed to be more closely related to the ion translocation than ATP formation. In the presence of Ca++ the energy of H+ gradient was utilized in translocating Ca++ rather than synthesizing ATP. These findings further substantiate the chemiosmotic theory of MITCHELL on mitochondrial electron and energy transfer.</p
Device and Methods for Atomizing Fluids
One embodiment of the invention is directed to an apparatus for atomizing a fluid. This apparatus includes an atomizing nozzle assembly. The atomizing nozzle assembly includes: a spray applicator enclosure having a fluid entry zone, a flow shape profiler region, a transducer, and a cavitation enhancer module, wherein the cavitation enhancer module includes a residence modulation zone and the residence modulation zone includes a backward facing step region. The apparatus is configured such that fluid can enter the fluid entry zone to the nozzle profiler, the transducer and the cavitation enhancer module. Other embodiments relate to methods for atomizing fluids
The Hydrogen Burning Turn-off of RS Ophiuchi 2006
We report a coordinated multi-band photometry of the RS Oph 2006 outburst and
highlight the emission line free y-band photometry that shows a mid-plateau
phase at y ~ 10.2 mag from day 40 to day 75 after the discovery followed by a
sharp drop of the final decline. Such mid-plateau phases are observed in other
two recurrent novae, U Sco and CI Aql, and are interpreted as a bright disk
irradiated by the white dwarf. We have calculated theoretical light curves
based on the optically thick wind theory and have reproduced the observed light
curves including the mid-plateau phase and the final sharp decline. This final
decline is identified with the end of steady hydrogen shell-burning, which
turned out the day ~80. This turnoff date is consistent with the end of a
supersoft X-ray phase observed with Swift. Our model suggests a white dwarf
mass of 1.35 \pm 0.01 M_\sun, which indicates that RS Oph is a progenitor of
Type Ia supernovae. We strongly recommend the y-filter observation of novae to
detect both the presence of a disk and the hydrogen burning turn-off.Comment: to appear in ApJL, 4 pages including 4 figure
Recommended from our members
SOX11 contributes to the regulation of GDF5 in joint maintenance
Background: Individual skeletal elements of the vertebrate limbs arise through a segmentation process introducing joints in specific locations. However, the molecular pathways controlling joint formation and subsequent joint maintenance are largely unknown. In this study, we focused on SOX11, and its contribution to the regulation of GDF5, a secreted signal necessary for proper joint formation and postnatal joint homeostasis. Results: Sox11 is initially expressed broadly in the murine cartilage condensations at early stages of skeletal development, but its expression is specifically increased in the forming joint interzone as is forms. SOX11 overexpression can directly activate GDF5 expression both in vitro and in micromass cell cultures prepared from chick limb buds. Conserved SOX family binding sites are present in the 5â UTR region of the GDF5 gene and we show SOX11 can specifically bind to one of them. While misexpression of Sox11 in developing chick limbs through RCAS virus infection does not induce Gdf5 expression in ectopic locations, it does enhance its expression. To explore the roles of Sox11 in joint homeostasis, we analyzed adult knee joints in an osteoarthritis mouse model where the medial meniscus and the medial collateral ligament were removed. We also analyzed knee joints from human subjects who underwent total knee replacement surgery. We find that SOX11 is mainly expressed in the weight-bearing areas of knee joints, and its expression is decreased in degraded cartilage during progression of knee osteoarthritis in both mice and humans. Conclusions: This work implicates SOX11 as a potential regulator of GDF5 expression in joint maintenance and suggests a possible role in the pathogenesis of osteoarthritis
A deformed analogue of Onsager's symmetry in the XXZ open spin chain
The XXZ open spin chain with general integrable boundary conditions is shown
to possess a q-deformed analogue of the Onsager's algebra as fundamental
non-abelian symmetry which ensures the integrability of the model. This
symmetry implies the existence of a finite set of independent mutually
commuting nonlocal operators which form an abelian subalgebra. The transfer
matrix and local conserved quantities, for instance the Hamiltonian, are
expressed in terms of these nonlocal operators. It follows that Onsager's
original approach of the planar Ising model can be extended to the XXZ open
spin chain.Comment: 12 pages; LaTeX file with amssymb; v2: typos corrected,
clarifications in the text; v3: minor changes in references, version to
appear in JSTA
Angle-resolved photoemission study of MX-chain compound [Ni(chxn)Br]Br
We report on the results of angle-resolved photoemission experiments on a
quasi-one-dimensional -chain compound [Ni(chxn)Br]Br (chxn =
1,2-cyclohexanediamine), a one-dimensional Heisenberg system with
and K, which shows a gigantic non-linear optical effect. A "band"
having about 500 meV energy dispersion is found in the first half of the
Brillouin zone , but disappears at . Two
dispersive features, expected from the spin-charge separation, as have been
observed in other quasi-one-dimensional systems like SrCuO, are not
detected. These characteristic features are well reproduced by the -
chain model calculations with a small charge-transfer energy compared
with that of one-dimensional Cu-O based compounds. We propose that this smaller
is the origin of the absence of clear spin- and charge-separation in
the photoemission spectra and strong non-linear optical effect in
[Ni(chxn)Br]Br.Comment: 4 pages, 3 figure
Evidence for a companion to BM Gem, a silicate carbon star
Balmer and Paschen continuum emission as well as Balmer series lines of P
Cygni-type profile from H_gamma through H_23 are revealed in the violet spectra
of BM Gem, a carbon star associated with an oxygen-rich circumstellar shell
(`silicate carbon star') observed with the high dispersion spectrograph (HDS)
on the Subaru telescope. The blue-shifted absorption in the Balmer lines
indicates the presence of an outflow, the line of sight velocity of which is at
least 400 km s^-1, which is the highest outflow velocity observed to date in a
carbon star. We argue that the observed unusual features in BM Gem are strong
evidence for the presence of a companion, which should form an accretion disk
that gives rise to both an ionized gas region and a high velocity, variable
outflow. The estimated luminosity of ~0.2 (0.03-0.6) L_sun for the ionized gas
can be maintained by a mass accretion rate to a dwarf companion of ~10^-8 M_sun
yr^-1, while ~10^-10 M_sun yr^-1 is sufficient for accretion to a white dwarf
companion. These accretion rates are feasible for some detached binary
configurations on the basis of the Bond-Hoyle type accretion process. We
concluded that the carbon star BM Gem is in a detached binary system with a
companion of low mass and low luminosity. However, we are unable to determine
whether this companion object is a dwarf or a white dwarf. The upper limits for
binary separation are 210 AU and 930 AU for a dwarf and a white dwarf,
respectively. We also note that the observed features of BM Gem mimic those of
Mira (omi Cet), which may suggest actual similarities in their binary
configurations and circumstellar structures.Comment: 11 pages, 2 figures, 1 table, accepted for publication in Ap
- âŠ