1,164 research outputs found
EFFECTS OF TEMPERING AND PWHT ON MICROSTRUCTURES AND MECHANICAL PROPERTIES OF SA508 GR.4N STEEL
Presented in this study are the variations of microstructures and mechanical properties with tempering and Post-Weld Heat Treatment (PWHT) conditions for SA508 Gr.4N steel used as Reactor Pressure Vessel (RPV) material. The blocks of model alloy were austenitized at the conventional temperature of 880 °C, then tempered and post-weld heat treated at four different conditions. The hardness and yield strength decrease with increased tempering and PWHT temperatures, but impact toughness is significantly improved, especially in the specimens tempered at 630 °C. The sample tempered at 630 °C with PWHT at 610 °C shows optimum mechanical properties in hardness, strength, and toughness, excluding only the transition property in the low temperature region. The microstructural observation and quantitative analysis of carbide size distribution show that the variations of mechanical properties are caused by the under-tempering and carbide coarsening which occurred during the heat treatment process. The introduction of PWHT results in the deterioration of the ductile-brittle transition property by an increase of coarse carbides controlling cleavage initiation, especially in the tempered state at 630 °C
Nanomedicine: Interaction of biomimetic apatite colloidal nanoparticles with human blood components
This contribution investigates the interaction of two types of biomimetic-apatite colloidal nanoparticles (negatively-charged 47nm, and positively-charged 190nm NPs) with blood components, namely red blood cells (RBC) and plasma proteins, with the view to inspect their hemocompatibility. The NPs, preliminarily characterized by XRD, FTIR and DLS, showed low hemolysis ratio (typically lower than 5%) illustrating the high compatibility of such NPs with respect to RBC, even at high concentration (up to 10mg/ml). The presence of glucose as water-soluble matrix for freeze-dried and re-dispersed colloids led to slightly increased hemolysis as compared to glucose-free formulations. NPs/plasma protein interaction was then followed, via non-specific protein fluorescence quenching assays, by contact with whole human blood plasma. The amount of plasma proteins in interaction with the NPs was evaluated experimentally, and the data were fitted with the Hill plot and Stern-Volmer models. In all cases, binding constants of the order of 101â102 were found. These values, significantly lower than those reported for other types of nanoparticles or molecular interactions, illustrate the fairly inert character of these colloidal NPs with respect to plasma proteins, which is desirable for circulating injectable suspensions. Results were discussed in relation with particle surface charge and mean particle hydrodynamic diameter (HD). On the basis of these hemocompatibility data, this study significantly complements previous results relative to the development and nontoxicity of biomimetic-apatite-based colloids stabilized by non-drug biocompatible organic molecules, intended for use in nanomedicine
Clinical nursesâ experiences of workplace verbal violence: a phenomenological study
Purpose This study aimed to describe clinical nursesâ lived experiences of workplace verbal violence through qualitative research using descriptive phenomenology. Methods Six female Korean nurses who had less than 5 years of clinical experience and had experienced verbal violence in the workplace within the past year participated in the study. Data were collected through one-on-one in-depth interviews with the participants and analyzed using Colaizziâs phenomenological method. Results A total of 27 codes, eight themes, and four theme clusters were derived from the participantsâ statements. The four theme clusters of the clinical nursesâ experiences of verbal violence in the workplace were as follows: âtip of the iceberg,â âbeyond me and my control,â âfear and resignation,â and âpersonal burden.â The participants recognized that nurses experienced verbal violence daily, and that the causes of and responses to verbal violence were determined by external situational factors rather than nursesâ individual problems. This suggests that nurses felt that they had no choice but to personally cope with verbal violence and bear the consequences due to systematic indifference and silence about verbal violence experienced by clinical nurses. Conclusion The findings show that verbal violence was pervasive and unmerited, yet often endured at the cost of a personal burden to nurses. A clear definition of verbal violence and education for employees are needed, and a reporting system should be established to report all forms of violence regardless of the severity of the incident
Interlayer Structure of Bioactive Molecule, 2-Aminoethanesulfonate, Intercalated into Calcium-Containing Layered Double Hydroxides
We have successfully intercalated 2-aminoethanesulfonate, a well-known biomolecule taurine, into calcium-containing layered double hydroxides via optimized solid phase intercalation. According to X-ray diffraction patterns and infrared spectroscopy, it was revealed that the intercalated taurine molecules were each directly coordinated to other calcium cation and arranged in a zig-zag pattern. Scanning electron microscopy showed that the particle size and morphology of the LDHs were not affected by the solid phase intercalation, and the surface of intercalates was covered by organic moieties. From ninhydrin amine detection tests, we confirmed that most of the taurine molecules were well stabilized between the calcium-containing LDH layers
Cultural Differences in How to Make Someone Love You
Undergraduate Research Opportunity Program (UROP)http://deepblue.lib.umich.edu/bitstream/2027.42/116109/1/Cultural_Differences_How_to_Make_Someone_Loveyou.pd
High resolution angle resolved photoemission studies on quasi-particle dynamics in graphite
We obtained the spectral function of the graphite H point using high
resolution angle resolved photoelectron spectroscopy (ARPES). The extracted
width of the spectral function (inverse of the photo-hole lifetime) near the H
point is approximately proportional to the energy as expected from the linearly
increasing density of states (DOS) near the Fermi energy. This is well
accounted by our electron-phonon coupling theory considering the peculiar
electronic DOS near the Fermi level. And we also investigated the temperature
dependence of the peak widths both experimentally and theoretically. The upper
bound for the electron-phonon coupling parameter is ~0.23, nearly the same
value as previously reported at the K point. Our analysis of temperature
dependent ARPES data at K shows that the energy of phonon mode of graphite has
much higher energy scale than 125K which is dominant in electron-phonon
coupling.Comment: 9 pages, 8 figures, accepted for publication in Phys. Rev.
Combined Brown syndrome and superior oblique palsy without a trochlear nerve: case report
CCDD: congenital cranial dysinnervation disorder; MRI: magnetic resonance imaging; RHT: right hypertropia; SO: superior obliqueAbstract
Background
Congenital Brown syndrome is characterized by limited elevation particularly during adduction. The pathogenesis of congenital Brown syndrome is still controversial.
Case presentation
A 6-year-old boy had been tilting his head to the left since infancy. He showed right hypertropia (RHT) of 2 prism diopters (Î) in the primary position. He showed RHT 6Î in right gaze, RHT 2Î in left gaze, RHT 12Î in right head tilt, and orthotropia in left head tilt. The right eye showed limitation of elevation and depression on adduction, and the left eye showed overdepression on adduction. MR images showed an absent right trochlear nerve with a hypoplastic ipsilateral superior oblique muscle.
Conclusions
Congenital Brown syndrome may be associated with an absent trochlear nerve and hypoplastic superior oblique muscle suggesting an etiologic mechanism of congenital cranial dysinnervation disorder
Machine-learning-assisted analysis of transition metal dichalcogenide thin-film growth
In situ reflective high-energy electron diffraction (RHEED) is widely used to
monitor the surface crystalline state during thin-film growth by molecular beam
epitaxy (MBE) and pulsed laser deposition. With the recent development of
machine learning (ML), ML-assisted analysis of RHEED videos aids in
interpreting the complete RHEED data of oxide thin films. The quantitative
analysis of RHEED data allows us to characterize and categorize the growth
modes step by step, and extract hidden knowledge of the epitaxial film growth
process. In this study, we employed the ML-assisted RHEED analysis method to
investigate the growth of 2D thin films of transition metal dichalcogenides
(ReSe2) on graphene substrates by MBE. Principal component analysis (PCA) and
K-means clustering were used to separate statistically important patterns and
visualize the trend of pattern evolution without any notable loss of
information. Using the modified PCA, we could monitor the diffraction intensity
of solely the ReSe2 layers by filtering out the substrate contribution. These
findings demonstrate that ML analysis can be successfully employed to examine
and understand the film-growth dynamics of 2D materials. Further, the ML-based
method can pave the way for the development of advanced real-time monitoring
and autonomous material synthesis techniques.Comment: 21 pages, 4 figure
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