13,552 research outputs found
CMAS corrosion of EB PVD TBCs: Identifying the minimum level to initiate damage
No full textOver the last decade a significant amount of research has been conducted into
the durability of thermal barrier coatings (TBCs) focusing mainly on issues of
oxidation, erosion and foreign object damage (FOD). However, as the performance
and durability of TBCs has improved the temperatures at which they operate has
increased. This increase in temperature has resulted in another lifing issue for
EB PVD TBCs, namely that of CMAS attack. Calciumâ  magnesiumâ  alumino-silicate
(CMAS) attack occurs when atmospheric dust that has deposited on the surface of
turbine blades melts and wicks into the columns of the TBC. This occurs at
temperatures above 1240â  1260 à °C and results in the degradation of the
columnar microstructure of the TBCs. Due to the fact that TBCs operate in a
temperature gradient CMAS only infiltrates part of the coating before
solidifying. There are a number of issues associated with CMAS attack, both
chemical and mechanical. From a chemical point of view CMAS attack of electron
beam (EB) physical vapour deposited (PVD) TBCs can be considered as a form of
corrosion; when there is a lot of excess CMAS on the surface of a coated
component Yttria diffuses out of the TBC into the molten CMAS resulting in a
tâ ² to monoclinic phase transformation in the yttria stabilised zirconia (YSZ),
CMAS attack also results in localised melting and subsequent re-precipitation of
the coating resulting in a loss of the defined columnar microstructure. While
from a mechanical point of view the CMAS, once re-solidified, reduces the strain
compliance of the EB PVD and can result in spallation of the TBC on cooling.
Furthermore, current studies have indicated that small amount of CMAS
infiltration significantly increases the erosion rate of EB PVD TBCs. This paper
covers various aspects of CMAS attack of EB PVD TBCs, specifically looking at
minimum levels of CMAS required to initiate damage, as well as investigating it
from an erosionâ  corrosion
Radioligand Therapy of Prostate Cancer with a Long-Lasting Prostate-Specific Membrane Antigen Targeting Agent <sup>90</sup>Y‑DOTA-EB-MCG
No full textSeveral
radioligands targeting prostate-specific membrane antigen
(PSMA) have been clinically introduced as a new class of radiotheranostics
for the treatment of prostate cancer. Among them, (((R)-1-carboxy-2-mcercaptoethyl)carbamoyl)-l-glutamic acid
(MCG) has been successfully labeled with radioisotopes for prostate
cancer imaging. The aim of this study is to conjugate MCG with an
albumin binding moiety to further improve the in vivo pharmacokinetics.
MCG was conjugated with an Evans blue (EB) derivative for albumin
binding and a DOTA chelator. PSMA positive (PC3-PIP) and PSMA negative
(PC3) cells were used for both in vitro and in vivo studies. Longitudinal
PET imaging was performed at 1, 4, 24, and 48 h post-injection to
evaluate the biodistribution and tumor uptake of 86Y-DOTA-EB-MCG.
DOTA-EB-MCG was also labeled with 90Y for radionuclide
therapy. Besides tumor growth measurement, tumor response to escalating
therapeutic doses were also evaluated by immunohistochemistry and
fluorescence microscopy. Based on quantification from 86Y-DOTA-EB-MCG PET images, the tracer uptake in PC3-PIP tumors increased
from 22.33 ± 2.39%ID/g at 1 h post-injection (p.i.), to the peak
of 40.40 ± 4.79%ID/g at 24 h p.i. Administration of 7.4 MBq of 90Y-DOTA-EB-MCG resulted in significant regression of tumor
growth in PSMA positive xenografts. No apparent toxicity or body weight
loss was observed in all treated mice. Modification of MCG with an
Evans blue derivative resulted in a highly efficient prostate cancer
targeting agent (EB-MCG), which showed great potential in prostate
cancer treatment after being labeled with therapeutic radioisotopes
NGTS-EB-7, an eccentric, long-period, low-mass eclipsing binary
No full textDespite being the most common types of stars in the Galaxy, the physical properties of late M dwarfs are often poorly constrained. A trend of radius inflation compared to evolutionary models has been observed for earlier type M dwarfs in eclipsing binaries, possibly caused by magnetic activity. It is currently unclear whether this trend also extends to later type M dwarfs below the convective boundary. This makes the discovery of lower mass, fully convective, M dwarfs in eclipsing binaries valuable for testing evolutionary models – especially in longer-period binaries where tidal interaction between the primary and secondary is negligible. With this context, we present the discovery of the NGTS-EB-7 AB system, an eclipsing binary containing a late M dwarf secondary and an evolved G-type primary star. The secondary star has a radius of R, a mass of M and follows a highly eccentric (e = ) orbit every d. This makes NGTS-EB-7 AB the third longest-period eclipsing binary system with a secondary smaller than 200 with the mass and radius constrained to better than 5 per cent. In addition, NGTS-EB-7 is situated near the centre of the proposed LOPS2 southern field of the upcoming PLATO mission, allowing for detection of the secondary eclipse and measurement of the companion’s temperature. With its long-period and well-constrained physical properties – NGTS-EB-7 B will make a valuable addition to the sample of M dwarfs in eclipsing binaries and help in determining accurate empirical mass/radius relations for later M dwarf stars.</p
Development of EB-PVD TBC'S : the role of deposition temperature and plasma assistance
No full textGas turbine manufacturers have achieved continuingly improved engine
efficiency and thrust-to-weight ratio by designing with increased Turbine
Entry Temperature (TET). The protection of High Pressure Turbine (HPT)
aerofoils with thin insulating ceramic coatings, referred to as Thermal Barrier
Coatings (TBC's), has emerged as the next key technology to allow for further
increases in TET. Electron Beam Physical Vapour Deposition (EB-PVD) is
today's most promising processing route for the manufacture of TBC's applied
on aerofoils.
The purpose of this work was to generate a sound understanding of the
relationship between the EB-PVD process and the structure of Zr02-
8wt%Y2O3 ceramic deposits, which could be exploited to achieve improved
TBC performance. In particular, the role of deposition temperature and the
potential benefits in using RF and DC plasma assistance of the EB-PVD
process were investigated, together with their influence on the erosion
performance of EB-PVD TBC's. The significance of particulate erosion as a
degradation mode is assessed under conditions representative of the HPT
environment. New explorable routes to achieve reduced thermal conductivity
of EB-PVD TBC's are identified.
It is shown that EB-PVD TBC's deposited at low temperature contain a
massive content of microscopic voidage (-50%) which is responsible for their
lack of thermal stability. The growth of EB-PVD TBC's at elevated deposition
temperatures is explained in terms of dynamic sintering, whereby diffusion
processes compete against the high rate arrival of vapour atoms to overcome
the spontaneous defectiveness of the atomic build up. Modelling of the gas
discharge physics has highlighted scope for improving the effectiveness of
plasma assistance in causing ceramic structural damage, capable of modifying
the coating thermal properties.
The erosion rate of EB-PVD TBC's is shown to be controlled by their degree
of plastic deformation upon particle impacts, which in turn depends on the
ceramic column diameter and inherent porosity
EB preparation, morphology and gene analysis.
No full text<p>(A) Preparation scheme for EB derived ECM scaffold. (B–C) Generation of EB via rotary suspension culture resulted in homogenous-sized EBs. Histology showing both groups of native EB – (D) SPT EB and (E) RA treated EB. Arrow heads indicate numerous cavities within the SPT EBs more than RA treated EB. (F–H) Quantification of gene expression via qRT-PCR shows that RA induces neural differentiation of EBs. (F) Nestin, (G) Pax6, and (H) Brachyury. Relative expression is normalized to SPT EB. H&E staining of EB sections shows presence of neural rosettes (dotted lines) in the (K) RA treated EBs confirming neuroepithelial tissue formation in contrast to (I) SPT EB. Immunohistochemical analysis of consecutive sections demonstrated positive for anti-Nestin staining in (J) RA treated EB but minimally expressed in (L) SPT EB. All values are mean ± SD, p<0.01(**), n = 3, represents pooled of EBs from 3 experimental repeats.</p
Effect of the administration of n-3 polyunsaturated fatty acids on circulating levels of microparticles in patients with a previous myocardial infarction
No full textMicrostructural damage of thermal barrier coatings due to CMAS
No full textOver recent years, due to a constant desire for higher efficiency engines and hence increased
turbine entry temperatures and a proportional reduction in [Carbon dioxide] emissions, there is a need to
understand how molten slags (CMAS: Calcia magnesia alumina-silicate), including volcanic
ash, affect engine life. Thermal barrier coatings (TBC) are employed together with cooling
technology to protect engine hardware from the high temperature seen within the turbine and
combustion zones. At current operating temperatures, CMAS can adhere to the TBC surface
resulting in premature degradation of the coating. The columnar, high porosity microstructure
of electron beam physical vapour deposited (EB-PVD) TBCs make them particularly
susceptible to CMAS/molten deposit attack. CMAS attack of PYSZ is reported in literature to
be characterised by penetration of the melt along the columnar structure, chemically attacking
the TBC whereupon yttria is leached from PYSZ and into the melt, creating an yttria depleted
interaction zone.
A new approach for classifying and reporting CMAS attack on TBCs is introduced in this
thesis and a degradation map is created to acknowledge that the mechanism and severity of
CMAS damage is related to variation in the CMAS compositions. CMAS degradation of EB-
PVD has been extensively studied by previous authors, all reporting similar degradation
mechanism with varying degree of severity. In this study, this category of CMAS degradation
mechanism is termed “classic” CMAS attack.
The primary aim of this study has been to investigate the damage caused by volcanic ash and
CMAS to materials used within an aerospace gas turbine engine. The thesis investigates two
aspects. It is recognised that, debris ingested by the engine will cause erosion damage to
components in the cooler section of the engine (compressor), thus the first part examines this issue. A series of erosion tests with Eyjafjallajokull volcanic ash and similar sized MIL spec
silica sand have been undertaken with two compressor-typical materials (Ti-6Al-4V and
Inconel 718). The results were consistent with volcanic ash behaving like fine silica sand
both at room and at compressor operating temperatures. The measured erosion rates are
consistent with a ductile erosion mechanism with peak rates of material loss at lower impact
angle. The results would appear to fit classical ductile erosion models where the material loss
depends on particle velocity and follows a power with an exponent close to 2.4
Evans Blue (EB) Method.
No full text<p>Increased EB content in brain tissue confirms increased BBB permeability post-I/R. Values are expressed in μg/g as means±SDs (n = 5 per group; *<i>P</i><0.05 versus the sham group, **<i>P</i><0.01 versus the sham group; #<i>P</i><0.05 versus the I/R group, and ##<i>P</i><0.01 versus the I/R group).</p
EB specifically inhibited the activation of STAT3.
No full text<p><b>(A)</b> Chemical structure of EB. <b>(B)</b> HepG2/STAT3-luceferase reporter cells were pretreated with EB at indicated concentrations for 2 h, and luciferase activity was measured following stimulation with IL-6 (50 ng/ml) for 5 h. Data are expressed as mean ± SD. *P < 0.05, **P < 0.01 and ***P < 0.001 versus the control group without EB but with IL-6 stimulation. <b>(C)</b> A549 cells were pretreated with EB at indicated concentrations for 2 h before stimulation by IL-6 (10 ng/ml) for 15 min. Whole cell lysates were processed for western blot analysis with the indicated antibodies. <b>(D)</b> A549 cells were pretreated with 20 μM EB for various time periods (0–120 min) before stimulation by IL-6 for 15 min. Whole cell lysates were processed for western blot analysis with the indicated antibodies. <b>(E)</b> MDA-MB-231 and MDA-MB-468 cells were treated with EB at indicated concentrations for 2 h. Whole cell lysates were processed for western blot analysis with indicated antibodies. <b>(F)</b> A549 cells were cultured on coverslips in serum-free medium for 24 h. The cells were then pretreated with vehicle or 10 μM EB for 2 h, followed by 30 min stimulation with IL-6. The cells on the coverslips were then processed for immunochemical staining with an anti-STAT3 antibody or nuclei staining with Diamidino-phenyl-indole. (<b>G</b>) EB and nuclear extract from A549 cells that contained activated STAT3 proteins were preincubated for 1h prior to addition of DNA probe. The STAT3 DNA-binding activity was assessed by EMSA. The oligo band shift caused by STAT3 binding and the super shift caused by the anti-STAT3 antibody binding are indicated. <b>(H)</b> A549 cells were treated with EB at indicated concentrations for 2 h, followed by stimulation with IFN-γ for 15 min. Whole cell lysates were processed for western blot analysis using the antibodies as indicated.</p
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