132 research outputs found
An EXAFS study of RuSr2GdCu2O8: evidence of magnetoelastic coupling
The EXAFS spectrum of two samples of RuSr2GdCu2O8 prepared by means of slightly different procedures was measured in the temperature range from 10 up to 300 K on the K-edge of Cu. Both the basal and the apical CuâO distances are not influenced by the magnetic and the superconducting transitions. Moreover the temperature dependence of the DebyeâWaller factors of the R(CuâObasal) distance for both samples is in agreement with the Debye model for thermal disorder. On the contrary, r2(CuâOapical) shows a clear peak around the magnetic transition. This effect is attributed to magnetoelastic couplin
UVES analysis of red giants in the bulge globular cluster NGC 6522
Context. NGC 6522 is a moderately metal-poor bulge globular cluster ([Fe/H] similar to-1.0), and it is a well-studied representative among a number of moderately metal-poor blue horizontal branch clusters located in the bulge. The NGC 6522 abundance pattern can give hints on the earliest chemical enrichment in the central Galaxy. Aims. The aim of this study is to derive abundances of the light elements C and N; alpha elements O, Mg, Si, Ca, and Ti; odd-Z elements Na and Al; neutron-capture elements Y, Zr, Ba, La, and Nd; and the r-process element Eu. We verify if there are first- and second-generation stars: we find clear evidence of Na-Al, Na-N, and Mg-Al correlations, while we cannot identify the Na-O anti-correlation from our data. Methods. High-resolution spectra of six red giants in the bulge globular cluster NGC 6522 were obtained at the 8m VLT UT2-Kueyen telescope with both the UVES and GIRAFFE spectrographs in FLAMES+UVES configuration. In light of Gaia data, it turned out that two of them are non-members, but these were also analysed. Spectroscopic parameters were derived through the excitation and ionisation equilibrium of Fe I and Fe II lines from UVES spectra. The abundances were obtained with spectrum synthesis. Comparisons of abundances derived from UVES and GIRAFFE spectra were carried out. Results. The present analysis combined with previous UVES results gives a mean radial velocity of v(r)(hel) r = -15.62 +/- 7.7 km s(-1) and a metallicity of [Fe/H] = 1.05 +/- 0.20 for NGC 6522. Mean abundances of alpha elements for the present four member stars are enhanced with [O/Fe] = +0.38, [Mg/Fe] = approximate to+0.28, [Si/Fe] approximate to +0.19; and [Ca/Fe] approximate to +0.13, together with the iron-peak element [Ti/Fe] approximate to +0.13, and the r-process element [Eu/Fe] = +0.40. The neutron-capture elements Y, Zr, Ba, and La show enhancements in the +0.08 < [Y/Fe] < +0.90, 0.11 < [Zr/Fe] < +0.50, 0.00 < [Ba/Fe] < +0.63, 0.00 < [La/Fe] < +0.45, and 0.10 < [Nd/Fe] < +0.70 ranges. We also discuss the spread in heavy-element abundances
UVES analysis of red giants in the bulge globular cluster NGC 6522
Context: NGC 6522 is a moderately metal-poor bulge globular cluster ([Fe/H] -1.0), and it is a well-studied representative among a number of moderately metal-poor blue horizontal branch clusters located in the bulge. The NGC 6522 abundance pattern can give hints on the earliest chemical enrichment in the central Galaxy. Aims: The aim of this study is to derive abundances of the light elements C and N; alpha elements O, Mg, Si, Ca, and Ti; odd-Z elements Na and Al; neutron-capture elements Y, Zr, Ba, La, and Nd; and the r-process element Eu. We verify if there are first-and second-generation stars: we find clear evidence of Na-Al, Na-N, and Mg-Al correlations, while we cannot identify the Na-O anti-correlation from our data. Methods: High-resolution spectra of six red giants in the bulge globular cluster NGC 6522 were obtained at the 8m VLT UT2-Kueyen telescope with both the UVES and GIRAFFE spectrographs in FLAMES+UVES configuration. In light of Gaia data, it turned out that two of them are non-members, but these were also analysed. Spectroscopic parameters were derived through the excitation and ionisation equilibrium of Fe I and Fe II lines from UVES spectra. The abundances were obtained with spectrum synthesis. Comparisons of abundances derived from UVES and GIRAFFE spectra were carried out. Results: The present analysis combined with previous UVES results gives a mean radial velocity of vrhel = -15.62±7.7 km s-1 and a metallicity of [Fe/H] = -1.05 ± 0.20 for NGC 6522. Mean abundances of alpha elements for the present four member stars are enhanced with [O/Fe] = +0.38, [Mg/Fe] = â+0.28, [Si/Fe] â +0.19, and [Ca/Fe] â +0.13, together with the iron-peak element [Ti/Fe] â +0.13, and the r-process element [Eu/Fe] = +0.40. The neutron-capture elements Y, Zr, Ba, and La show enhancements in the +0.08 < [Y/Fe] < +0.90, 0.11 < [Zr/Fe] < +0.50, 0.00 < [Ba/Fe] < +0.63, 0.00 < [La/Fe] < +0.45, and -0.10 < [Nd/Fe] < +0.70 ranges. We also discuss the spread in heavy-element abundances
A preclinical pipeline to evaluate migrastatics as therapeutic agents in metastatic melanoma
© The Author(s) 2021.[Background]: Metastasis is a hallmark of cancer and responsible for most cancer deaths. Migrastatics were defined as drugs interfering with all modes of cancer cell invasion and thus cancersâ ability to metastasise. First anti-metastatic treatments have recently been approved.
[Methods]: We used bioinformatic analyses of publicly available melanoma databases. Experimentally, we performed in vitro target validation (including 2.5D cell morphology analysis and mass spectrometric analysis of RhoA binding partners), developed a new traceable spontaneously metastasising murine melanoma model for in vivo validation, and employed histology (haematoxylin/eosin and phospho-myosin II staining) to confirm drug action in harvested tumour tissues.
[Results]: Unbiased and targeted bioinformatic analyses identified the Rho kinase (ROCK)-myosin II pathway and its various components as potentially relevant targets in melanoma. In vitro validation demonstrated redundancy of several RhoGEFs upstream of RhoA and confirmed ROCK as a druggable target downstream of RhoA. The anti-metastatic effects of two ROCK inhibitors were demonstrated through in vivo melanoma metastasis tracking and inhibitor effects also confirmed ex vivo by digital pathology.
[Conclusions]: We proposed a migrastatic drug development pipeline. As part of the pipeline, we provide a new traceable spontaneous melanoma metastasis model for in vivo quantification of metastasis and anti-metastatic effects by non-invasive imaging.GOFâs lab was supported by Cancer Research UK [C48390/A21153], Worldwide Cancer Research [16-1153], and Kingâs Health Partners [Kingâs Medical Research Trust Joint Research Committee studentship to A.V.]. B.F. was supported by a Kingâs Health Partners studentship to V.S.M. and G.O.F. V.S.M.âs lab was supported by Cancer Research UK [C33043/A12065] and [C33043/A24478] (V.S.M., E.C.M., J.L.O., L.B. and GC), the Royal Society [RG110591] (V.S.M.), The Harry J. Lloyd Charitable Trust (J.L.O. and V.S.M.), the Barts Charity (V.S.M., J.L.O., O.M., I.R.H. and E.C.M.), the Fundacion Alfonso Martin Escudero and Marie Sklodowska-Curie Action [H2020-MSCA-IF-2014-EF-ST] (I.R.H.), and Fundacion Ramon Areces (E.C.M.). F.M. was supported by an MRC Career Development Award (MR/P009417/1). This work was further supported by the Department of Health (DoH) via the National Institute for Health Research (NIHR) Comprehensive Biomedical Research Centre award to Kingâs Health Partners, and the Wellcome/EPSRC Centre for Medical Engineering [WT203148/Z/16/Z]. Views expressed are those of the authors and not necessarily those of the NHS, NIHR or DoH
UVES analysis of red giants in the bulge globular cluster NGC 6522
Context. NGC 6522 is a moderately metal-poor bulge globular cluster ([Fe/H] ~ â1.0), and it is a well-studied representative among a number of moderately metal-poor blue horizontal branch clusters located in the bulge. The NGC 6522 abundance pattern can give hints on the earliest chemical enrichment in the central Galaxy. Aims. The aim of this study is to derive abundances of the light elements C and N; alpha elements O, Mg, Si, Ca, and Ti; odd-Z elements Na and Al; neutron-capture elements Y, Zr, Ba, La, and Nd; and the r-process element Eu. We verify if there are first- and second-generation stars: we find clear evidence of NaâAl, NaâN, and MgâAl correlations, while we cannot identify the NaâO anti-correlation from our data. Methods. High-resolution spectra of six red giants in the bulge globular cluster NGC 6522 were obtained at the 8m VLT UT2-Kueyen telescope with both the UVES and GIRAFFE spectrographs in FLAMES+UVES configuration. In light of Gaia data, it turned out that two of them are non-members, but these were also analysed. Spectroscopic parameters were derived through the excitation and ionisation equilibrium of Fe I and Fe II lines from UVES spectra. The abundances were obtained with spectrum synthesis. Comparisons of abundances derived from UVES and GIRAFFE spectra were carried out. Results. The present analysis combined with previous UVES results gives a mean radial velocity of vrhel = â15.62±7.7 km sâ1 and a metallicity of [Fe/H] = â1.05 ± 0.20 for NGC 6522. Mean abundances of alpha elements for the present four member stars are enhanced with [O/Fe] = +0.38, [Mg/Fe] = â+0.28, [Si/Fe] â +0.19, and [Ca/Fe] â +0.13, together with the iron-peak element [Ti/Fe] â +0.13, and the r-process element [Eu/Fe] = +0.40. The neutron-capture elements Y, Zr, Ba, and La show enhancements in the +0.08 < [Y/Fe] < +0.90, 0.11 < [Zr/Fe] < +0.50, 0.00 < [Ba/Fe] < +0.63, 0.00 < [La/Fe] < +0.45, and â0.10 < [Nd/Fe] < +0.70 ranges. We also discuss the spread in heavy-element abundances
WNT11-FZD7-DAAM1 signalling supports tumour initiating abilities and melanoma amoeboid invasion
Melanoma is a highly aggressive tumour that can metastasize very early in disease progression. Notably, melanoma can disseminate using amoeboid invasive strategies. We show here that high Myosin II activity, high levels of ki-67 and high tumour-initiating abilities are characteristic of invasive amoeboid melanoma cells. Mechanistically, we find that WNT11-FZD7-DAAM1 activates Rho-ROCK1/2-Myosin II and plays a crucial role in regulating tumour-initiating potential, local invasion and distant metastasis formation. Importantly, amoeboid melanoma cells express both proliferative and invasive gene signatures. As such, invasive fronts of human and mouse melanomas are enriched in amoeboid cells that are also ki-67 positive. This pattern is further enhanced in metastatic lesions. We propose eradication of amoeboid melanoma cells after surgical removal as a therapeutic strategy. Amoeboid cells are associated with melanoma invasive capacity. Here, the authors show that the WNT11-FZD7-DAAM1 pathway regulates tumour-initiating potential, invasion and metastasis lead by amoeboid cells in the invasive front of melanoma tumours
Developments in the NiâNbâZr amorphous alloy membranes
Most of the global H2 production is derived from hydrocarbon-based fuels, and efficient H2/CO2 separation is necessary to deliver a high-purity H2 product. Hydrogen-selective alloy membranes are emerging as a viable alternative to traditional pressure swing adsorption processes as a means for H2/CO2 separation. These membranes can be formed from a wide range of alloys, and those based on Pd are the closest to commercial deployment. The high cost of Pd (USD *31,000 kg-1) is driving the development of less-expensive alternatives, including inexpensive amorphous (Ni60Nb40)100-xZrx alloys. Amorphous alloy membranes can be fabricated directly from the molten state into continuous ribbons via melt spinning and depending on the composition can exhibit relatively high hydrogen permeability between 473 and 673 K. Here we review recent developments in these low-cost membrane materials, especially with respect to permeation behavior, electrical transport properties, and understanding of local atomic order. To further understand the nature of these solids, atom probe tomography has been performed, revealing amorphous Nb-rich and Zr-rich clusters embedded in majority Ni matrix whose compositions deviated from the nominal overall composition of the membrane
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