24 research outputs found
Polydimethylsiloxane (PDMS)-based microfluidic channel with integrated commercial pressure sensors
The precise characterisation of boiling in microchannels is essential for the optimisation of applications requiring two phase cooling. In this paper polydimethylsiloxane (PDMS) is employed to make microchannels for characterising microboiling. In particular the material properties of PDMS facilitate rapid prototyping and its optical transparency provides the capability to directly view any fluid flow. The production of microchannels is complicated by the need to integrate custom made sensors. This paper presents a PDMS microfluidic device with integrated commercial pressure sensors, which have been used to perform a detailed characterisation of microboiling phenomena. The proposed approach of integrating commercial pressure sensors into the channel also has potential applications in a range of other microsystems
Enhancement of low- kaons in AGS heavy-ion collisions
In the relativistic transport model, we show that the recently observed
enhancement of low- kaons ( and ) in Si+Pb collisions at AGS can
be explained if a density isomer is introduced in the nuclear
equation-of-state.Comment: 12 pages, RevTex, 6 figs on request to [email protected]
11β-hydroxysteroid dehydrogenase type I inhibition in solid tumours
Glucocorticoids, key hormonal regulators of the stress response, powerfully influence
inflammation and metabolism. Reducing excessive glucocorticoid exposure is
beneficial in treating metabolic and cognitive disorders, but manipulating systemic
endogenous glucocorticoids risks compromising their beneficial effects. The enzyme
11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) activates glucocorticoids in
target tissues and thus inhibition of this enzyme presents a clinical opportunity to
reduce tissue-specific glucocorticoid action. Active glucocorticoids also exert potent
angiostatic effects by binding the glucocorticoid receptor (GR), and 11β-HSD1
inhibitors have proven beneficial in models of myocardial infarction by promoting
angiogenesis. The possibility that 11β-HSD1 inhibitors may increase pathological
angiogenesis, such as that seen in solid tumours, remains unaddressed. This project
tested the hypothesis that 11β-HSD1 inhibition promotes tumour growth as a result of
increased angiogenesis, using murine models of squamous cell carcinoma (SCC) and
pancreatic ductal adenocarcinoma (PDAC).
Murine SCC or PDAC cells were injected (1x106 cells/flank) into WT female mice fed
either standard diet, or diet containing the 11β-HSD1 inhibitor UE2316 (175 mg/kg,
N=6/group), or into 11β-HSD1 knockout (Del1) mice fed standard diet. Developing
tumours were measured by callipers over several weeks, before animals were culled
and tissues collected. SCC tumours grew more rapidly in UE2316-treated mice to
reach a significantly (P<0.01) larger final volume (0.158 ± 0.037 cm3) than in control
mice (0.051 ± 0.007 cm3). PDA tumours were unaffected by 11β-HSD1 inhibition or
deletion. Immunofluorescent co-staining of tumour sections for CD31/α-smooth
muscle actin revealed no differences in vessel density, and RT-qPCR showed no
difference in angiogenic factor expression, after 11β-HSD1 inhibition/deletion in
either tumour type. GR and 11β-HSD1 RNA expression were greater in SCC vs PDAC
tumours (P<0.001), as was 11β-HSD1 activity (P<0.0001).
In studies using the aortic ring assay of ex vivo angiogenesis, 11β-HSD1 deletion, but
not inhibition with UE2316, was shown to prevent glucocorticoid-mediated
angiostasis. The growth/viability of tumour cell lines was not affected by UE2316 or
corticosterone, as assessed by live cell imaging using the Incucyte imaging system.
RNA-sequencing of SCC tumours revealed that multiple factors involved in the innate
immune/inflammatory response were reduced in UE2316-treated tumours, and that
extracellular matrix regulation was also altered by UE2316. Imaging of tumour
sections using Second Harmonic Generation microscopy confirmed that UE2316
altered Type I collagen deposition in SCC (P<0.001) but not PDAC.
11β-HSD1 inhibition can increase tumour growth, possibly via suppression of
inflammatory/immune cell signalling and alteration of the extracellular matrix, and
tumours with higher GR and 11β-HSD1 content, such as SCC, may be more at risk.
Interestingly this investigation found no evidence of increased angiogenesis in vivo or
ex vivo after UE2316 treatment, suggesting that 11β-HSD1 inhibition does not
promote angiogenesis in all ischaemic environments. Future work must focus on the
effects of 11β-HSD1 inhibition on the immune and extracellular matrix component of
the tumour microenvironment. While promotion of pathological angiogenesis does not
appear to pose a major threat, 11β-HSD1 inhibitors may still interact with the immune
and inflammatory environment in tumours to the detriment of health
The hyperon-nucleon interaction: conventional versus effective field theory approach
Hyperon-nucleon interactions are presented that are derived either in the
conventional meson-exchange picture or within leading order chiral effective
field theory. The chiral potential consists of one-pseudoscalar-meson exchanges
and non-derivative four-baryon contact terms. With regard to meson-exchange
hyperon-nucleon models we focus on the new potential of the Juelich group,
whose most salient feature is that the contributions in the scalar--isoscalar
(\sigma) and vector--isovector (\rho) exchange channels are constrained by a
microscopic model of correlated \pi\pi and KKbar exchange.Comment: 28 pages, 8 figures, submitted to Lecture Notes in Physic
Off-axis symbiosis found: characterization and biogeography of bacterial symbionts of Bathymodiolus mussels from Lost City hydrothermal vents
Density dependent hadron field theory for neutron stars with antikaon condensates
We investigate and condensation in -equilibrated
hyperonic matter within a density dependent hadron field theoretical model. In
this model, baryon-baryon and (anti)kaon-baryon interactions are mediated by
the exchange of mesons. Density dependent meson-baryon coupling constants are
obtained from microscopic Dirac Brueckner calculations using Groningen and Bonn
A nucleon-nucleon potential. It is found that the threshold of antikaon
condensation is not only sensitive to the equation of state but also to
antikaon optical potential depth. Only for large values of antikaon optical
potential depth, condensation sets in even in the presence of negatively
charged hyperons. The threshold of condensation is always reached
after condensation. Antikaon condensation makes the equation of state
softer thus resulting in smaller maximum mass stars compared with the case
without any condensate.Comment: 20 pages, 7 figures; final version to appear in Physical Review
Natural Abundance 14C Content of Dibutyl Phthalate (DBP) from Three Marine Algae
Abstract: Analysis of the natural abundance 14C content of dibutyl phthalate (DBP) from two edible brown algae, Undaria pinnatifida and Laminaria japonica, and a green alga, Ulva sp., revealed that the DBP was naturally produced. The natural abundance 14C content of di-(2-ethylhexyl) phthalate (DEHP) obtained from the same algae was about 50-80% of the standard sample and the 14C content of the petrochemical (industrial) products of DBP and DEHP were below the detection limit