94 research outputs found
New borate ester based polymer electrolyte for battery application
Safety is an indispensable feature for a battery
particularly in large scale applications. In this respect, gel
electrolytes are more attractive due to less possibility of
electrolyte leakage and safer if abused. Unfortunately,
most present gel electrolyte systems are mainly based on
polyethers which supposed to be flammable. In addition,
PEO and PPO based systems exhibit a low cation
transference number. Therefore, the seeking of novel
thermally stable and safety polymer electrolytes with
improved electrochemical behaviour is crucial. In the
present contribution, we propose a series of Li-ion
conducting polymer electrolytes based on the
poly(ethyleneglycol) (PEG) borate ester (PE-350B) and
PEG-methacrylates (PME-400 and PDE-600,
respectively) plasticized by M550B100 PEG-borate ester,
which can be characterized as a thermally stable solvent
with high flash point [1]
Extracting the Redox Orbitals in Li Battery Materials with High-Resolution X-Ray Compton Scattering Spectroscopy
We present an incisive spectroscopic technique for directly probing redox
orbitals based on bulk electron momentum density measurements via
high-resolution x-ray Compton scattering. Application of our method to spinel
LixMn2O4, a lithium ion battery cathode material, is discussed. The orbital
involved in the lithium insertion and extraction process is shown to mainly be
the oxygen 2p orbital. Moreover, the manganese 3d states are shown to
experience spatial delocalization involving 0.16 electrons per Mn site during
the battery operation. Our analysis provides a clear understanding of the
fundamental redox process involved in the working of a lithium ion battery.Comment: 24 pages, 3 figure
Characterization of the distribution of the Lly\alpha emitters in the 53W002 field at z = 2.4
We present the results of our wide-field narrow band imaging of the field
around the radio galaxy 53W002 at z = 2.390 with Subaru/Suprime-Cam. A custom
made filter NB413 centered at 4140 \AA\ with the width of 83 \AA\ is used to
observe the 31' x 24' area around the radio galaxy. We detected 204 Ly\alpha
emitters (LAEs) at z = 2.4 with a rest frame equivalent width larger than 25
\AA\ to the depth of 26 AB mag (in NB413). The entire LAE population in the
53W002 field has an average number density and distributions of equivalent
width and size that are similar to those of other fields at z ~ 2. We identify
a significant high density region (53W002F-HDR) that spreads over ~ 5' x 4'
near 53W002 where the LAE number density is nearly four times as large as the
average of the entire field. Using the probability distribution function of
density fluctuation, we evaluate the rareness probability of the 53W002F-HDR to
be 0.9^{+2.4}_{-0.62}%, which corresponds to a moderately rich structure. No
notable environmental dependency at the comoving scale of 10 Mpc is found for
the distributions of the Ly\alpha equivalent width and luminosity in the field.
We also detected 4 Ly\alpha blobs (LABs), one of which is newly discovered.
They are all found to be located in the rims of high density regions. The
biased location and unique morphologies in Ly\alpha suggest that galaxy
interaction play a key role in their formation.Comment: 26 pages, 12 figure
White Lines and 3d-Occupancy for the 3d Transition-Metal Oxides
Electron energy-loss spectrometry was employed to measure the white lines at
the L23 absorption edges of the 3d transition-metal oxides and lithium
transition-metal oxides. The white-line ratio (L3/L2) was found to increase
between d^0 and d^5 and decrease between d^5 and d^10, consistent with previous
results for the transition metals and their oxides. The intensities of the
white lines, normalized to the post-edge background, are linear for the 3d
transition-metal oxides and lithium transition-metal oxides. An empirical
correlation between normalized white-line intensity and 3d occupancy is
established. It provides a method for measuring changes in the 3d-state
occupancy. As an example, this empirical relationship is used to measure
changes in the transition-metal valences of Li_{1-x}Ni_{0.8}Co_{0.2}O_2 in the
range of 0 < x < 0.64. In these experiments the 3d occupancy of the nickel ion
decreased upon lithium deintercalation, while the cobalt valence remained
constant.Comment: 6 pages, 7 figure
MOIRCS Deep Survey. VIII. Evolution of Star Formation Activity as a Function of Stellar Mass in Galaxies since z~3
We study the evolution of star formation activity of galaxies at 0.5<z<3.5 as
a function of stellar mass, using very deep NIR data taken with Multi-Object
Infrared Camera and Spectrograph (MOIRCS) on the Subaru telescope in the
GOODS-North region. The NIR imaging data reach K ~ 23-24 Vega magnitude and
they allow us to construct a nearly stellar mass-limited sample down to ~
10^{9.5-10} Msun even at z~3. We estimated star formation rates (SFRs) of the
sample with two indicators, namely, the Spitzer/MIPS 24um flux and the
rest-frame 2800A luminosity. The SFR distribution at a fixed Mstar shifts to
higher values with increasing redshift at 0.5<z<3.5. More massive galaxies show
stronger evolution of SFR at z>~1. We found galaxies at 2.5<z<3.5 show a
bimodality in their SSFR distribution, which can be divided into two
populations by a constant SSFR of ~2 Gyr^{-1}. Galaxies in the low-SSFR group
have SSFRs of ~ 0.5-1.0 Gyr^{-1}, while the high-SSFR population shows ~10
Gyr^{-1}. The cosmic SFRD is dominated by galaxies with Mstar = 10^{10-11} Msun
at 0.5<z<3.5, while the contribution of massive galaxies with Mstar =
10^{11-11.5} Msun shows a strong evolution at z>1 and becomes significant at
z~3, especially in the case with the SFR based on MIPS 24um. In galaxies with
Mstar = 10^{10-11.5} Msun, those with a relatively narrow range of SSFR (<~1
dex) dominates the cosmic SFRD at 0.5<z<3.5. The SSFR of galaxies which
dominate the SFRD systematically increases with redshift. At 2.5<z<3.5, the
high-SSFR population, which is relatively small in number, dominates the SFRD.
Major star formation in the universe at higher redshift seems to be associated
with a more rapid growth of stellar mass of galaxies.Comment: 16 pages, 13 figures, accepted for publication in Ap
MOIRCS Deep Survey IV: Evolution of Galaxy Stellar Mass Function Back to z ~ 3
We use very deep near-infrared (NIR) imaging data obtained in MOIRCS Deep
Survey (MODS) to investigate the evolution of the galaxy stellar mass function
back to z~3. The MODS data reach J=24.2, H=23.1, K=23.1 (5sigma, Vega
magnitude) over 103 arcmin^2 (wide) and J=25.1, H=23.7, K=24.1 over 28 arcmin^2
(deep) in the GOODS-North region. The wide and very deep NIR data allow us to
measure the number density of galaxies down to low stellar mass (10^9-10^10
Msun) even at high redshift with high statistical accuracy. The normalization
of the mass function decreases with redshift and the integrated stellar mass
density becomes ~ 8-18% of the local value at z~2 and ~ 4-9% at z~3, which are
consistent with results of previous studies in general fields. Furthermore, we
found that the low-mass slope becomes steeper with redshift from alpha ~- 1.3
at z~1 to alpha ~- 1.6 at z~3, and that the evolution of the number density of
low-mass (10^9-10^10 Msun) galaxies is weaker than that of M* (~10^11 Msun)
galaxies. This indicates that the contribution of low-mass galaxies to the
total stellar mass density has been significant at high redshift. The
steepening of the low-mass slope with redshift is opposite trend expected from
the stellar mass dependence of the specific star formation rate reported in
previous studies. The present result suggests that the hierarchical merging
process overwhelmed the effect of the stellar mass growth by star formation and
was very important for the stellar mass assembly of these galaxies at 1<~z<~3.Comment: 21 pages, 18 figures, accepted for publication in Ap
Mechanisms controlling dissolved iron distribution in the North Pacific : a model study
Author Posting. © American Geophysical Union, 2011. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 116 (2011): G03005, doi:10.1029/2010JG001541.Mechanisms controlling the dissolved iron distribution in the North Pacific are investigated using the Biogeochemical Elemental Cycling (BEC) model with a resolution of approximately 1° in latitude and longitude and 60 vertical levels. The model is able to reproduce the general distribution of iron as revealed in available field data: surface concentrations are generally below 0.2 nM; concentrations increase with depth; and values in the lower pycnocline are especially high in the northwestern Pacific and off the coast of California. Sensitivity experiments changing scavenging regimes and external iron sources indicate that lateral transport of sedimentary iron from continental margins into the open ocean causes the high concentrations in these regions. This offshore penetration only appears under a scavenging regime where iron has a relatively long residence time at high concentrations, namely, the order of years. Sedimentary iron is intensively supplied around continental margins, resulting in locally high concentrations; the residence time with respect to scavenging determines the horizontal scale of elevated iron concentrations. Budget analysis for iron reveals the processes by which sedimentary iron is transported to the open ocean. Horizontal mixing transports sedimentary iron from the boundary into alongshore currents, which then carry high iron concentrations into the open ocean in regions where the alongshore currents separate from the coast, most prominently in the northwestern Pacific and off of California.This work was supported
by the U.S. National Science Foundation (EF‐0424599)
MOIRCS Deep Survey III: Active Galactic Nuclei in Massive Galaxies at z=2-4
We investigate the X-ray properties of the K-band-selected galaxies at
redshift 2 < z < 4 by using our deep near-infrared images obtained in the
MOIRCS Deep Survey project and the published Chandra X-ray source catalog. 61
X-ray sources with the 2-10 keV luminosity L_X = 10^{42}-10^{44} erg/s are
identified with the K-selected galaxies and we found that they are exclusively
(90%) associated with the massive objects with stellar mass larger than
10^{10.5} Msun. Our results are consistent with the idea that the M_BH/M_str
ratio of the galaxies at z=2-4 is similar to the present-day value. On the
other hand, the AGN detection rate among the very massive galaxies with the
stellar mass larger than 10^{11} Msun is high, 33% (26/78). They are active
objects in the sense that the black-hole mass accretion rate is ~ 1-50% of the
Eddington limit if they indeed have similar M_BH/M_str ratio with those
observed in the local universe. The active duration in the AGN duty cycle of
the high-redshift massive galaxies seems large.Comment: 33 pages, 12 figures, accepted for publication in Ap
Delithiation/lithiation behavior of LiNi<inf>0.5</inf>Mn<inf>1.5</inf>O<inf>4</inf> studied by in situ and ex situ <sup>6,7</sup>Li NMR spectroscopy
Delithiation and lithiation behaviors of ordered spinel LiNi0.5Mn1.5O4 and disordered spinel LiNi0.4Mn1.6O4 were investigated by using in situ (in operando) 7Li NMR and ex situ 6Li MAS NMR spectroscopy. The in situ 7Li monitoring of the ordered spinel revealed a clear appearance and subsequent disappearance of a new signal from the well-defined phase Li0.5Ni0.5Mn1.5O4, suggesting the two-phase reaction processes among Li1.0Ni0.5Mn1.5O4, Li0.5Ni0.5Mn1.5O4, and Li0.0Ni0.5Mn1.5O4. Also, for the disordered spinel, Li0.5Ni0.4Mn1.6O4 was identified with a broad distribution in Li environment. High-resolution 6Li MAS NMR spectra were also acquired for the delithiated and lithiated samples to understand the detailed local structure around Li ions. We suggested that the nominal Li-free phase Li0.0Ni0.5Mn1.5O4 can accommodate a small amount of Li ions in its structure. The tetragonal phases Li2.0Ni0.5Mn1.5O4 and Li2.0Ni0.4Mn1.6O4, which occurred when the cell was discharged down to 2.0 V, were very different in the Li environment from each other. It is found that 6, 7Li NMR is highly sensitive not only to the Ni/Mn ordering in LiNi0.5Mn1.5O4 but also to the valence changes of Ni and Mn on charge-discharge process
Loss of the interferon-γ-inducible regulatory immunity-related GTPase (IRG), Irgm1, causes activation of effector IRG proteins on lysosomes, damaging lysosomal function and predicting the dramatic susceptibility of Irgm1-deficient mice to infection
The interferon-γ (IFN-γ)-inducible immunity-related GTPase (IRG), Irgm1, plays an essential role in restraining activation of the IRG pathogen resistance system. However, the loss of Irgm1 in mice also causes a dramatic but unexplained susceptibility phenotype upon infection with a variety of pathogens, including many not normally controlled by the IRG system. This phenotype is associated with lymphopenia, hemopoietic collapse, and death of the mouse.Deutscher Akademischer Austausch Dienst (DAAD); International Graduate School in Development Health
and Disease (IGS-DHD); Deutsche For-schungsgemeinschaft (SFBs 635, 670, 680); Max-Planck-Gesellschaft (Max Planck Fellowship)
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