| 1. |
- Dell'Angela, M., et al.
(author)
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Real-Time Observation of Surface Bond Breaking with an X-ray Laser
- 2013
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In: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 339:6125, s. 1302-1305
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Journal article (peer-reviewed)abstract
- We used the Linac Coherent Light Source free-electron x-ray laser to probe the electronic structure of CO molecules as their chemisorption state on Ru(0001) changes upon exciting the substrate by using a femtosecond optical laser pulse. We observed electronic structure changes that are consistent with a weakening of the CO interaction with the substrate but without notable desorption. A large fraction of the molecules (30%) was trapped in a transient precursor state that would precede desorption. We calculated the free energy of the molecule as a function of the desorption reaction coordinate using density functional theory, including van der Waals interactions. Two distinct adsorption wells-chemisorbed and precursor state separated by an entropy barrier-explain the anomalously high prefactors often observed in desorption of molecules from metals.
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| 2. |
- Beye, M., et al.
(author)
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Selective Ultrafast Probing of Transient Hot Chemisorbed and Precursor States of CO on Ru(0001)
- 2013
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 110:18
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Journal article (peer-reviewed)abstract
- We have studied the femtosecond dynamics following optical laser excitation of CO adsorbed on a Ru surface by monitoring changes in the occupied and unoccupied electronic structure using ultrafast soft x-ray absorption and emission. We recently reported [M. Dell'Angela et al. Science 339, 1302 (2013)] a phonon-mediated transition into a weakly adsorbed precursor state occurring on a time scale of >2 ps prior to desorption. Here we focus on processes within the first picosecond after laser excitation and show that the metal-adsorbate coordination is initially increased due to hot-electron-driven vibrational excitations. This process is faster than, but occurs in parallel with, the transition into the precursor state. With resonant x-ray emission spectroscopy, we probe each of these states selectively and determine the respective transient populations depending on optical laser fluence. Ab initio molecular dynamics simulations of CO adsorbed on Ru(0001) were performed at 1500 and 3000 K providing insight into the desorption process.
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| 3. |
- Katayama, T., et al.
(author)
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Ultrafast soft X-ray emission spectroscopy of surface adsorbates using an X-ray free electron laser
- 2013
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In: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048 .- 1873-2526. ; 187, s. 9-14
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Journal article (peer-reviewed)abstract
- We report on an experimental system designed to probe chemical reactions on solid surfaces on a sub-picosecond timescale using soft X-ray emission spectroscopy at the Linac Coherent Light Source (LCLS) free electron laser (FEL) at the SLAC National Accelerator Laboratory. We analyzed the O 1s X-ray emission spectra recorded from atomic oxygen adsorbed on a Ru(0001) surface at a synchrotron beamline (SSRL, BL13-2) and an FEL beamline (LCLS, SXR). We have demonstrated conditions that provide negligible amount of FEL induced damage of the sample. In addition we show that the setup is capable of tracking the temporal evolution of electronic structure during a surface reaction of submonolayer quantities of CO molecules desorbing from the surface.
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| 4. |
- Kocyigit, I, et al.
(author)
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Early arterial stiffness and inflammatory bio-markers in normotensive polycystic kidney disease patients
- 2012
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In: American journal of nephrology. - : S. Karger AG. - 1421-9670 .- 0250-8095. ; 36:1, s. 11-18
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Journal article (peer-reviewed)abstract
- <b><i>Background/Aims:</i></b> Cardiovascular disease is the main cause of morbidity and mortality in autosomal-dominant polycystic kidney disease (ADPKD) patients. To clarify temporal relationship between ADPKD, hypertension and the loss of renal function, we examined these factors in patients with early-stage ADPKD who did not yet have hypertension. <b><i>Methods:</i></b> Fifty patients with ADPKD (42% males, 36.6 ± 9.9 years, no blood pressure medication) and 50 healthy controls (44% males, 35.4 ± 6.4 years) were studied cross-sectionally. Pulse wave velocity (PWV), cardiac morphology and function, aortic elastic indexes, estimated glomerular filtration rate (eGFR), 24-hour ambulatory blood pressure, interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and highly sensitive C-reactive protein (hs-CRP) were measured in all participants, using conventional methods. <b><i>Results:</i></b> Despite a normal blood pressure, aortic stiffness index and pulse wave velocity values were increased in patients compared to controls (6.8 ± 4.7 vs. 5.1 ± 3.3, p = 0.043 and 9.6 ± 1.3 vs. 5.8 ± 1.1 m/s, p < 0.001). In univariate analysis, IL-6, TNF-α, hs-CRP and eGFR were all significantly correlated with PWV. The independence of these correlations were analyzed in a regression model, and showed PWV to be significantly predicted by IL-6, TNF-α and hs-CRP. <b><i>Conclusion:</i></b> Increased arterial stiffness and pulse wave velocity are early manifestations of ADPKD appearing before hypertension or reduced eGFR. However, these vascular abnormalities are related to signs of systemic low grade inflammation, suggesting a common pathophysiological mechanism apparently present also in other vascular diseases but yet to be elucidated.
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| 5. |
- Cserni, Gabor, et al.
(author)
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Distinction of isolated tumour cells and micrometastasis in lymph nodes of breast cancer patients according to the new Tumour Node Metastasis (TNM) definitions
- 2011
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In: European Journal of Cancer. - : Elsevier BV. - 1879-0852 .- 0959-8049. ; 47:6, s. 887-894
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Journal article (peer-reviewed)abstract
- Isolated tumour cells and micrometastases represent two different staging categories and are often dealt with differently when identified in sentinel lymph nodes of breast cancer patients. The reproducibility of these categories was found to be suboptimal in several studies. The new edition of the TNM (Tumour Node Metastasis) is expected to improve the reproducibility of these categories. Fifty cases of possible low-volume nodal involvement were represented by one to four digital images and were analysed by members of the European Working Group for Breast Screening Pathology (EWGBSP). The kappa value for interobserver agreement of the pN (TNM) staging categories and of the isolated tumour cells category were 0.55 and 0.56 reflecting moderate reproducibility, and the kappa of the micrometastatic category (0.62) reflected substantial reproducibility. This is an improvement over the results gained on the basis of the previous edition of the TNM. Maximal adherence to the category definitions supplemented by explanatory texts in the staging manual should result in more homogeneous nodal staging of breast cancer. (C) 2010 Elsevier Ltd. All rights reserved.
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| 6. |
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| 7. |
- Jinek, Martin, et al.
(author)
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Structures of Cas9 Endonucleases Reveal RNA-Mediated Conformational Activation
- 2014
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In: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 343:6176, s. 1215-
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Journal article (peer-reviewed)abstract
- Type II CRISPR (clustered regularly interspaced short palindromic repeats)-Cas (CRISPR-associated) systems use an RNA-guided DNA endonuclease, Cas9, to generate double-strand breaks in invasive DNA during an adaptive bacterial immune response. Cas9 has been harnessed as a powerful tool for genome editing and gene regulation in many eukaryotic organisms. We report 2.6 and 2.2 angstrom resolution crystal structures of two major Cas9 enzyme subtypes, revealing the structural core shared by all Cas9 family members. The architectures of Cas9 enzymes define nucleic acid binding clefts, and single-particle electron microscopy reconstructions show that the two structural lobes harboring these clefts undergo guide RNA-induced reorientation to form a central channel where DNA substrates are bound. The observation that extensive structural rearrangements occur before target DNA duplex binding implicates guide RNA loading as a key step in Cas9 activation.
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| 8. |
- Lam, Yat-Yin, et al.
(author)
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Left ventricular and ascending aortic function after stenting of native coarctation of aorta.
- 2010
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In: American Journal of Cardiology. - : Elsevier BV. - 0002-9149 .- 1879-1913. ; 105:9, s. 1343-1347
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Journal article (peer-reviewed)abstract
- Patients with surgically corrected aortic coarctation have increased proximal aortic stiffness that might contribute to the known worse cardiovascular outcomes. We examined the effect of stenting on the mid-term ascending aortic elastic properties and its relation to cardiac structure and function in adults with native coarctation of the aorta. A total of 20 consecutive patients (13 men, age at stenting 30 + or - 8 years) were prospectively studied before and 14 + or - 2 months after coarctation stenting. The aortic stiffness index was calculated using the ascending aortic diameters and right arm blood pressure values. The ventricular long-axis function was assessed using pulsed-wave tissue Doppler imaging at the septal site. The results were compared to those from 31 normal controls. Statistically significant improvement was found in aortic narrowing (catheter-derived gradient 32 + or - 11 vs 10 + or - 6 mm Hg), left ventricular mass index (132.8 + or - 50.1 vs 114.7 + or - 47.7 g/m(2)), long-axis function, and left atrial volume index (26.5 + or - 5.3 vs 23.7 + or - 5.6 mm(3)/m(2)). The patients continued to have a thicker left ventricle, reduced long-axis function, and larger left atrium after intervention than did the controls. They also had impaired proximal aortic function with respect to the controls that remained unchanged after stenting (aortic stiffness index 10.7 + or - 4.5 to 10.1 + or - 3.0). The poststenting aortic stiffness index correlated modestly with the left ventricular mass index and reduced long-axis velocity. In conclusion, aortic stenting resulted in partial mid-term improvement in cardiac structure and function in adults with coarctation of aorta but the ascending aortic elastic properties remained abnormal. Such a degree of impairment was related to residual left ventricular hypertrophy and dysfunction. Early identification of such patients and optimum management might avoid these irreversible ventriculoaortic disturbances and their known consequences.
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| 9. |
- Nilsson, Anders, et al.
(author)
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X-ray absorption spectroscopy and X-ray Raman scattering of water and ice; an experimental view
- 2010
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In: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048 .- 1873-2526. ; 177:03-feb, s. 99-129
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Journal article (peer-reviewed)abstract
- Here we present a review of X-ray absorption spectroscopy and X-ray Raman scattering with the perspective to understand the spectra of water including changes with temperature, mass of the water molecule and presence of monovalent ions. The different detection schemes are discussed and it is concluded that transmission X-ray absorption measurements, using a small area where the thickness is uniform, and X-ray Raman scattering give the most reliable spectra. Different model systems are discussed such as the surface and bulk of ice and various adsorbed monolayer structures on metal surfaces.
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| 10. |
- Sellberg, Jonas A., et al.
(author)
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Comparison of x-ray absorption spectra between water and ice : New ice data with low pre-edge absorption cross-section
- 2014
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In: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 141:3, s. 034507-
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Journal article (peer-reviewed)abstract
- The effect of crystal growth conditions on the O K-edge x-ray absorption spectra of ice is investigated through detailed analysis of the spectral features. The amount of ice defects is found to be minimized on hydrophobic surfaces, such as BaF2(111), with low concentration of nucleation centers. This is manifested through a reduction of the absorption cross-section at 535 eV, which is associated with distorted hydrogen bonds. Furthermore, a connection is made between the observed increase in spectral intensity between 544 and 548 eV and high-symmetry points in the electronic band structure, suggesting a more extended hydrogen-bond network as compared to ices prepared differently. The spectral differences for various ice preparations are compared to the temperature dependence of spectra of liquid water upon supercooling. A double-peak feature in the absorption cross-section between 540 and 543 eV is identified as a characteristic of the crystalline phase. The connection to the interpretation of the liquid phase O K-edge x-ray absorption spectrum is extensively discussed.
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