10,286 research outputs found
Antimony-doped graphene nanoplatelets
Heteroatom doping into the graphitic frameworks have been intensively studied for the development of metal-free electrocatalysts. However, the choice of heteroatoms is limited to non-metallic elements and heteroatom-doped graphitic materials do not satisfy commercial demands in terms of cost and stability. Here we realize doping semimetal antimony (Sb) at the edges of graphene nanoplatelets (GnPs) via a simple mechanochemical reaction between pristine graphite and solid Sb. The covalent bonding of the metalloid Sb with the graphitic carbon is visualized using atomic-resolution transmission electron microscopy. The Sb-doped GnPs display zero loss of electrocatalytic activity for oxygen reduction reaction even after 100,000 cycles. Density functional theory calculations indicate that the multiple oxidation states (Sb3+ and Sb5+) of Sb are responsible for the unusual electrochemical stability. Sb-doped GnPs may provide new insights and practical methods for designing stable carbon-based electrocatalystsclose0
The association of statin use after cancer diagnosis with survival in pancreatic cancer patients: a SEER-medicare analysis.
BackgroundPancreatic cancer has poor prognosis and existing interventions provide a modest benefit. Statin has anti-cancer properties that might enhance survival in pancreatic cancer patients. We sought to determine whether statin treatment after cancer diagnosis is associated with longer survival in those with pancreatic ductal adenocarcinoma (PDAC).MethodsWe analyzed data on 7813 elderly patients with PDAC using the linked Surveillance, Epidemiology, and End Results (SEER) - Medicare claims files. Information on the type, intensity and duration of statin use after cancer diagnosis was extracted from Medicare Part D. We treated statin as a time-dependent variable in a Cox regression model to determine the association with overall survival adjusting for follow-up, age, sex, race, neighborhood income, stage, grade, tumor size, pancreatectomy, chemotherapy, radiation, obesity, dyslipidemia, diabetes, chronic pancreatitis and chronic obstructive pulmonary disease (COPD).ResultsOverall, statin use after cancer diagnosis was not significantly associated with survival when all PDAC patients were considered (HR = 0.94, 95%CI 0.89, 1.01). However, statin use after cancer diagnosis was associated with a 21% reduced hazard of death (Hazard ratio = 0.79, 95% confidence interval (CI) 0.67, 0.93) in those with grade I or II PDAC and to a similar extent in those who had undergone a pancreatectomy, in those with chronic pancreatitis and in those who had not been treated with statin prior to cancer diagnosis.ConclusionsWe found that statin treatment after cancer diagnosis is associated with enhanced survival in patients with low-grade, resectable PDAC
Radiative and Collisional Energy Loss, and Photon-Tagged Jets at RHIC
The suppression of single jets at high transverse momenta in a quark-gluon
plasma is studied at RHIC energies, and the additional information provided by
a photon tag is included. The energy loss of hard jets traversing through the
medium is evaluated in the AMY formalism, by consistently taking into account
the contributions from radiative events and from elastic collisions at leading
order in the coupling. The strongly-interacting medium in these collisions is
modelled with (3+1)-dimensional ideal relativistic hydrodynamics. Putting these
ingredients together with a complete set of photon-production processes, we
present a calculation of the nuclear modification of single jets and
photon-tagged jets at RHIC.Comment: 4 pages, 4 figures, contributed to the 3rd International Conference
on Hard and Electro-Magnetic Probes of High-Energy Nuclear Collisions (Hard
Probes 2008), typos corrected, published versio
Charge fluctuations and electric mass in a hot meson gas
Net-Charge fluctuations in a hadron gas are studied using an effective
hadronic interaction. The emphasis of this work is to investigate the
corrections of hadronic interactions to the charge fluctuations of a
non-interacting resonance gas. Several methods, such as loop, density and
virial expansions are employed. The calculations are also extended to SU(3) and
some resummation schemes are considered. Although the various corrections are
sizable individually, they cancel to a large extent. As a consequence we find
that charge fluctuations are rather well described by the free resonance gas.Comment: 32 pages, 18 figure
Production and optical properties of liquid scintillator for the JSNS experiment
The JSNS (J-PARC Sterile Neutrino Search at J-PARC Spallation Neutron
Source) experiment will search for neutrino oscillations over a 24 m short
baseline at J-PARC. The JSNS inner detector will be filled with 17 tons
of gadolinium-loaded liquid scintillator (LS) with an additional 31 tons of
unloaded LS in the intermediate -catcher and outer veto volumes.
JSNS has chosen Linear Alkyl Benzene (LAB) as an organic solvent because
of its chemical properties. The unloaded LS was produced at a refurbished
facility, originally used for scintillator production by the RENO experiment.
JSNS plans to use ISO tanks for the storage and transportation of the LS.
In this paper, we describe the LS production, and present measurements of its
optical properties and long term stability. Our measurements show that storing
the LS in ISO tanks does not result in degradation of its optical properties.Comment: 7 pages, 4 figures
Fluorescent and photo-oxidizing TimeSTAMP tags track protein fates in light and electron microscopy.
Protein synthesis is highly regulated throughout nervous system development, plasticity and regeneration. However, tracking the distributions of specific new protein species has not been possible in living neurons or at the ultrastructural level. Previously we created TimeSTAMP epitope tags, drug-controlled tags for immunohistochemical detection of specific new proteins synthesized at defined times. Here we extend TimeSTAMP to label new protein copies by fluorescence or photo-oxidation. Live microscopy of a fluorescent TimeSTAMP tag reveals that copies of the synaptic protein PSD95 are synthesized in response to local activation of growth factor and neurotransmitter receptors, and preferentially localize to stimulated synapses in rat neurons. Electron microscopy of a photo-oxidizing TimeSTAMP tag reveals new PSD95 at developing dendritic structures of immature neurons and at synapses in differentiated neurons. These results demonstrate the versatility of the TimeSTAMP approach for visualizing newly synthesized proteins in neurons
The North Ecliptic Pole Wide survey of AKARI: a near- and mid-infrared source catalog
We present a photometric catalog of infrared (IR) sources based on the North
Ecliptic PoleWide field (NEP-Wide) survey of AKARI, which is an infrared space
telescope launched by Japan. The NEP-Wide survey covered 5.4 deg2 area, a
nearly circular shape centered on the North Ecliptic Pole, using nine
photometric filter-bands from 2 - 25 {\mu}m of the Infrared Camera (IRC).
Extensive efforts were made to reduce possible false objects due to cosmic ray
hits, multiplexer bleeding phenomena around bright sources, and other
artifacts. The number of detected sources varied depending on the filter band:
with about 109,000 sources being cataloged in the near-IR bands at 2 - 5
{\mu}m, about 20,000 sources in the shorter parts of the mid-IR bands between 7
- 11 {\mu}m, and about 16,000 sources in the longer parts of the mid-IR bands,
with \sim 4,000 sources at 24 {\mu}m. The estimated 5? detection limits are
approximately 21 magnitude (mag) in the 2 - 5 {\mu}m bands, 19.5 - 19 mag in
the 7 - 11 {\mu}m, and 18.8 - 18.5 mag in the 15 - 24 {\mu}m bands in the AB
magnitude scale. The completenesses for those bands were evaluated as a
function of magnitude: the 50% completeness limits are about 19.8 mag at 3
{\mu}m, 18.6 mag at 9 {\mu}m, and 18 mag at 18 {\mu}m band, respectively. To
construct a reliable source catalog, all of the detected sources were examined
by matching them with those in other wavelength data, including optical and
ground-based near-IR bands. The final band-merged catalog contains about
114,800 sources detected in the IRC filter bands. The properties of the sources
are presented in terms of the distributions in various color-color diagrams.Comment: Accepted for publication in A&A, 23 pages, 27 figure
Spin-Orbit Coupling in Iridium-Based 5d Compounds Probed by X-ray Absorption Spectroscopy
We have performed x-ray absorption spectroscopy (XAS) measurements on a
series of Ir-based 5d transition metal compounds, including Ir, IrCl3, IrO2,
Na2IrO3, Sr2IrO4, and Y2Ir2O7. By comparing the intensity of the "white-line"
features observed at the Ir L2 and L3 absorption edges, it is possible to
extract valuable information about the strength of the spin-orbit coupling in
these systems. We observe remarkably large, non-statistical branching ratios in
all Ir compounds studied, with little or no dependence on chemical composition,
crystal structure, or electronic state. This result confirms the presence of
strong spin-orbit coupling effects in novel iridates such as Sr2IrO4, Na2IrO3,
and Y2Ir2O7, and suggests that even simple Ir-based compounds such as IrO2 and
IrCl3 may warrant further study. In contrast, XAS measurements on Re-based 5d
compounds, such as Re, ReO2, ReO3, and Ba2FeReO6, reveal statistical branching
ratios and negligible spin-orbit coupling effects.Comment: 9 pages, 4 figure
Scalar density fluctuation at critical end point in NJL model
Soft mode near the critical end point in the phase diagram of two-flavor
Nambu--Jona-Lasinio (NJL) model is investigated within the leading 1/N_c
approximation with N_c being the number of the colors. It is explicitly shown
by studying the spectral function of the scalar channel that the relevant soft
mode is the scalar density fluctuation, which is coupled with the quark number
density, while the sigma meson mode stays massive.Comment: 9 pages, 4 figure
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