Apparatus for low temperature thermal desorption spectroscopy of portable samples

An experimental setup for low temperaturethermal desorption spectroscopy (TDS) integrated in an ultrahigh vacuum-chamber housing a high-end scanning probe microscope for comprehensive multi-tool surface science analysis is described. This setup enables the characterization with TDS at low temperatures (T > 22 K) of portable sample designs, as is the case for scanning probe optimized setups or high-throughput experiments. This combination of techniques allows a direct correlation between surface morphology, local spectroscopy, and reactivity of model catalysts. The performance of the multi-tool setup is illustrated by measurements of a model catalyst. TDS of CO from Mo(001) and from Mo(001) supported MgO thin films were carried out and combined with scanning tunneling microscopy measurements

Local Magnetic and Electronic Structure of the Surface Region of Postsynthesis Oxidized Iron Oxide Nanoparticles for Magnetic Resonance Imaging

Iron oxide nanoparticles FeOx NP are applied in medicine as contrast agents in magnetic resonance imaging MRI where they reduce the spin amp; 8722;spin relaxation time T2 time of absorbing tissue. Hence, control of their magnetic properties is essential for these applications. Magnetic properties strongly depend on the particle size and shape as well as the surface functionalization of the iron oxide nanoparticles. Especially, structural and magnetic disorder in the region close to the surface 1 amp; 8722;2 nm lead usually to a reduced magnetization compared to the corresponding bulk material. Therefore, X ray magnetic circular dichroism XMCD in the total electron yield TEY mode is used to investigate local magnetic and electronic properties of the surface region of monodisperse, spherical FeOx NPs Fe3O4 amp; 947; Fe2O3 before and after the postsynthetic treatment in oxygen rich environment. Charge transfer multiplet calculations of the XMCD spectra are performed to analyze the contributions of Fe2 and Fe3 at different lattice sites, i.e., either in octahedral or tetrahedral environment. The analysis of the XMCD data reveals that both, the magnetization of the nanoparticle surface region as well as their maghemite to magnetite ratio, are strongly increased after tempering in an oxidative environment, which likely causes rearrangement of their crystalline order. The magnitude and the kinetics of these variables depend strongly on the particle size. In addition, after thermal annealing a reduced spin canting is extrapolated from the lower magnetic coercivity, which confirms that a structural rearrangement takes plac

Rho GDP dissociation inhibitor alpha expression correlates with the outcome of CMF treatment in invasive ductal breast cancer.

Rho-GDIalpha is an inhibitor of Rho-GTPases, which is involved in cancer progression. Little is known about its role in breast cancer progression. There is evidence, that Rho-GDIalpha may modulate drug resistance of breast cancer cells. To assess the importance of Rho-GDIalpha as a risk factor in invasive ductal breast cancer, cancer specimens of three groups of patients were analyzed for Rho-GDIalpha RNA (group 1, N=72 and group 2, N=73) or protein expression (group 3, N=90). In group 1, patients did not receive any adjuvant treatment, whereas, in groups 2 and 3, patients were treated with anti-estrogens and/or with chemotherapeutical drugs. Rho-GDIalpha RNA levels, measured by RT-PCR from fresh-frozen material, did not correlate with relapse-free survival in Kaplan-Meier analysis, except in a subgroup of CMF-only treated patients. In this subgroup, higher Rho-GDIalpha RNA levels were significantly associated with more favorable prognosis. Immunohistochemical analysis (group 3) confirmed the link between higher Rho-GDIalpha expression and better outcome. This was again particularly true for the CMF-only treated patients. Cox regression analysis revealed that high Rho-GDIalpha protein expression reduced the risk for a relapse by approximately 3-fold, even if adjusted for grading, tumor size, nodal and estrogen receptor (ER) status. The data suggest that Rho-GDIalpha is beneficial to patients who received adjuvant chemotherapy. Rho-GDIalpha is possibly a useful biomarker to predict the response of breast cancer patients to CMF treatment

Electron-Stimulated Hydroxylation of Silica Bilayer Films Grown on Ru(0001): A Combined HREELS and EPR Study

Electron-assisted hydroxylation of single-crystalline silica bilayer films grown on Ru(0001) is studied by high-resolution electron energy loss spectroscopy (HREELS) and electron paramagnetic resonance (EPR) spectroscopy. The HREELS results reveal the formation of several hydroxyl species whose number and speciation depend on the defect structure of the film. For incomplete bilayer films, which exhibit nanometer-sized holes in the bilayer, the level of hydroxylation is significantly larger than for complete films. HREEL spectra taken in off-specular geometry provide evidence for the presence of hydroxyl groups with a transition dipole moment almost parallel to the surface for complete and incomplete bilayer films. Hydroxylation with isotopically labeled water (H218O) reveals a clear difference between the two cases─OH species on the incomplete film almost exclusively contain oxygen from water, while the more ideal film exhibits OH groups with oxygen atoms stemming from both water and the silica film. These observations not only indicate that the degree of hydroxylation is significantly enhanced for the incomplete film but also that the reaction mechanism for hydroxylation at defect sites of this film is different. To gain insight into the reaction mechanism of electron-assisted hydroxylation, in situ EPR spectroscopy of electron-bombarded adsorbed ice layers was combined with infrared (IR) spectroscopy and mass spectrometry. We show that the electron bombardment removes a significant part of the water layer and produces different reactive paramagnetic species, namely, O2D, D, and solvated electrons, which may be trapped at low temperatures. The interaction of the silica film with such species may lead to splitting Si–O bonds even for covalently saturated silica structures as found in the ideal bilayer film and thus provide insight into possible reaction mechanisms

Cyclooxygenase-2 is a target gene of rho GDP dissociation inhibitor beta in breast cancer cells.

Contains fulltext : 52535.pdf (publisher's version ) (Closed access)Rho GDP dissociation inhibitor beta (Rho-GDI beta), an inhibitor of Rho GTPases, is primarily expressed by hematopoietic cells but is also found in epithelial cancer cells. Recently, we have identified Rho-GDI beta as a target of the transcription factor Ets1. Here, we show that, in breast cancer cells, Ets1 regulates Rho-GDI beta expression and binds to the upstream region of the Rho-GDI beta gene. Furthermore, in primary breast cancer, Rho-GDI beta is coexpressed with Ets1. Studying the function of Rho-GDI beta in breast cancer, we found that a Rho-GD beta-specific small interfering RNA increased cellular migration but also decreased the expression of cyclooxygenase-2 (Cox-2) oncogene as shown by microarray, quantitative reverse transcription-PCR, and Western blot analyses. Further studies revealed that Rho-GDI beta regulates Cox-2 gene at least partly on the transcriptional level, most likely by activating nuclear factor of activated T cells 1 (NFAT-1). Vav-1, an interaction partner of Rho-GDI beta, was also found to interfere with Cox-2 expression and NFAT-1 cellular distribution, suggesting a cooperative action of Rho-GDI beta and Vav-1 on Cox-2 expression. To explore the importance of Rho-GDI beta for the survival of breast cancer patients, two cohorts, including 263 and 117 patients, were analyzed for clinical outcome in relation to Rho-GDI beta RNA and protein levels, respectively. Expression of Rho-GDI beta was not associated with either disease-free or overall survival in the two patient population. Our data suggest that the expression of Rho-GDI beta in breast cancer is neither beneficial nor disadvantageous to the patient. This may be the net effect of two opposing activities of Rho-GDI beta, one that suppresses tumor progression by inhibiting migration and the other that stimulates it by enhancing Cox-2 expression