1,257 research outputs found
Well-defined ultrathin Pd films on Pt(111): electrochemical preparation and interfacial chemistry
Well-defined ultrathin films of palladium, with coverages ranging from
submonolayer, ΘPd = 0.5 monolayer (ML), to multilayer, ΘP d = 8 ML, were
electrochemically deposited on Pt(111) using potentiostatic and potentiodynamic
methods. In both methods, between the coverage regimes studied, the growth of the Pd
films follows the Stranski-Krastanov mechanism.
The interfacial electrochemical properties associated with the film-to-bulk
transition were characterized by conventional voltammetric techniques in combination
with low-energy electron diffraction (LEED) and Auger electron spectroscopy (AES).
The voltammetric peaks associated with H-atom adsorption and desorption on terrace
sites indicate that the Pd electrodeposit starts to exhibit bulk-like properties at a coverage
of 3 ML.
Voltammetric cycling, in sulfuric acid solution, between the hydrogen evolution
and the double-layer regions, was found to exert minimal influence on the annealing
(smoothening) of the electrodeposited Pd films. However, cycling within the same
potential region in the presence of bromide anions (at which Br- adsorption/Br
desorption takes place) smoothens the initially rough Pd films essentially as well as
high-temperature annealing.
The influence of chemisorbed bromine on the anodic dissolution of Pd was also
studied; this was for comparison with previous work on the anodic dissolution of Pd, in
inert electrolyte, catalyzed by chemisorbed iodine. The present studies indicated that a
small but measurable amount of bromine was desorbed along with dissolution of the Pd
step atoms; bromine at the Pd terrace behaved identically to iodine in that the coverage
of iodine is maintained regardless of the amount or origin of the of anodically stripped
Pd.
Atomically smooth, well-defined ultrathin Pd films were prepared by a constant
potential deposition (CPD) method followed by multiple potential cycles, in dilute Brsolution,
within the double-layer region and reductive removal of Brads, by simple
emersion at a potential just before the hydrogen evolution reaction potential (EHER). A
previously adapted method for the same purpose involved the chemisorption of iodine
onto ultrathin PdCPD films, from dilute I- solution, followed by reductive desorption of
Iads in iodide-free solution at pH 10 and at a potential just before EHER
Recommended from our members
Cardiovascular Disease Risk Factors Related to Shift Work among Korean Workers Aged from 30 to 49 Years
This study was to compare health behaviors between day workers (DW ) and shift workers (SW), and to investigate the cardiovascular disease (CVD) risk factors among 30-49 years Korean workers. SW showed higher prevalence of smoking than DW. The proportion of adequate sleep was lower in SW than in DW. DW showed high.er prevalence of impaired fasting glucose, however, there were no significant differences in hypertension, obesity, hypercholesterolemia, and metabolic syndrome between DW and SW. Further research is recommended to include mediating factors such as organizational culture or working time, etc., for scrutinizing the association between work type and CVD risk factors
Estimating Hourly Population Distribution Patterns at High Spatiotemporal Resolution in Urban Areas Using Geo-Tagged Tweets and Dasymetric Mapping
Association of epicardial fat with left ventricular diastolic function in subjects with metabolic syndrome: assessment using 2-dimensional echocardiography
Background
Metabolic syndrome (MetS) is related with left ventricular diastolic dysfunction (LVDD) and poor cardiovascular outcome. Epicardial adipose tissue (EAT) thickness, measured by echocardiography, is increased in subjects with MetS. However, the association of EAT with LV diastolic function has not been evaluated in subjects with MetS.
Methods
In this retrospective study, EAT thickness was measured in 1,486 consecutive asymptomatic patients with no known heart disease who had transthoracic echocardiography during a self-referred healthcare exam. Subjects with a history of ischemic heart disease, cardiomyopathy or significant valvular heart disease were excluded. LVDD was defined as E/e ratio ≥ 15. Subjects were grouped into two groups, those with MetS and those without.
Results
MetS was present in 346 subjects. There was no difference in LV systolic function between the two groups. However compared to patients without MetS, patients with MetS had larger left atrium (LA) size and higher E/e ratio (38 ± 5 versus 35 ± 5 mm for LA and 10.0 ± 3.3 versus 8.7 ± 2.7 for E/e ratio in subjects with versus without MetS both p < 0.001). LVDD was found in 27 (7.8%) subjects with MetS, compared to 30 (2.6%) subjects without MetS (p < 0.001). In subjects with MetS, EAT was significantly correlated with LVDD, even after adjusting for other cardiometabolic risk factors such as age, systolic blood pressure, BMI, blood glucose and LDL cholesterol (OR 1.845, 95% CI 1.153-2.951, p = 0.011).This study was supported by Seoul National University Hospital (0420100700, 2010–1096).Peer Reviewe
A General Theory of Correct, Incorrect, and Extrinsic Equivariance
Although equivariant machine learning has proven effective at many tasks,
success depends heavily on the assumption that the ground truth function is
symmetric over the entire domain matching the symmetry in an equivariant neural
network. A missing piece in the equivariant learning literature is the analysis
of equivariant networks when symmetry exists only partially in the domain. In
this work, we present a general theory for such a situation. We propose
pointwise definitions of correct, incorrect, and extrinsic equivariance, which
allow us to quantify continuously the degree of each type of equivariance a
function displays. We then study the impact of various degrees of incorrect or
extrinsic symmetry on model error. We prove error lower bounds for invariant or
equivariant networks in classification or regression settings with partially
incorrect symmetry. We also analyze the potentially harmful effects of
extrinsic equivariance. Experiments validate these results in three different
environments.Comment: Published at NeurIPS 202
Measurement of the Background Activities of a 100Mo-enriched powder sample for AMoRE crystal material using a single high purity germanium detector
The Advanced Molybdenum-based Rare process Experiment (AMoRE) searches for
neutrino-less double-beta (0{\nu}\b{eta}\b{eta}) decay of 100Mo in enriched
molybdate crystals. The AMoRE crystals must have low levels of radioactive
contamination to achieve low background signals with energies near the Q-value
of the 100Mo 0{\nu}\b{eta}\b{eta} decay. To produce low-activity crystals,
radioactive contaminants in the raw materials used to form the crystals must be
controlled and quantified. 100EnrMoO3 powder, which is enriched in the 100Mo
isotope, is of particular interest as it is the source of 100Mo in the
crystals. A high-purity germanium detector having 100% relative efficiency,
named CC1, is being operated in the Yangyang underground laboratory. Using CC1,
we collected a gamma spectrum from a 1.6-kg 100EnrMoO3 powder sample enriched
to 96.4% in 100Mo. Activities were analyzed for the isotopes 228Ac, 228Th,
226Ra, and 40K. They are long-lived naturally occurring isotopes that can
produce background signals in the region of interest for AMoRE. Activities of
both 228Ac and 228Th were < 1.0 mBq/kg at 90% confidence level (C.L.). The
activity of 226Ra was measured to be 5.1 \pm 0.4 (stat) \pm 2.2 (syst) mBq/kg.
The 40K activity was found as < 16.4 mBq/kg at 90% C.L.Comment: 20 pages, 6 figures, 5 table
Unexpected difficulty in ventilating the lungs after tracheal intubation -A case report-
We experienced difficulty in ventilating the lungs of a patient after tracheal intubation. After intubation, an insufficient amount of tidal volume (VT) was delivered to the patient and the fiberoptic bronchoscopic examination identified partial abutment of the endotracheal tube (ETT) orifice against the tracheal wall. After various attempts to correctly place the ETT, a double-lumen endotracheal tube was placed to achieve a sufficient VT. It is important to notice that even an appropriately placed ETT may get obstructed due to the left sided bevel at its tip
Toward Green Synthesis of Graphene Oxide Using Recycled Sulfuric Acid via Couette-Taylor Flow
Developing eco-friendly and cost-effective processes for the synthesis of graphene oxide (GO) is essential for its widespread industrial applications. In this work, we propose a green synthesis technique for GO production using recycled sulfuric acid and filter-processed oxidized natural graphite obtained from a Couette-Taylor flow reactor. The viscosity of reactant mixtures processed from Couette-Taylor flow was considerably lower (???200 cP at 25 ??C) than that of those from Hummers' method, which enabled the simple filtration process. The filtered sulfuric acid can be recycled and reused for the repetitive GO synthesis with negligible differences in the as-synthesized GO qualities. This removal of sulfuric acid has great potential in lowering the overall GO production cost as the amount of water required during the fabrication process, which takes a great portion of the total production cost, can be dramatically reduced after such acid filtration. The proposed eco-friendly GO fabrication process is expected to promote the commercial application of graphene materials into industry shortly
Fatal pulmonary embolism and coincidental cerebral infarction after spinal anesthesia -A case report-
A pulmonary embolism and cerebral infarction are the second and third most common acute cardiovascular diseases after a myocardial infarction. Early diagnosis and appropriate management are important clinical challenges. In this case, a fatal pulmonary embolism and extensive cerebral infarction caused cardiac arrest during spinal anesthesia for total hip replacement surgery. Transesophageal echocardiography indicated a pulmonary embolism and brain CT showed large area of acute infarction at right middle cerebral artery territory. Pulmonary CT angiogram revealed massive pulmonary embolism findings. This paper reviews this case and suggests other preventive modalities
- …