SwePub - search: WFRF:(Knudsen Jan)

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1.	Zamora, Juan Carlos, et al. (author) Considerations and consequences of allowing DNA sequence data as types of fungal taxa 2018 In: IMA Fungus. - : INT MYCOLOGICAL ASSOC. - 2210-6340 .- 2210-6359. ; 9:1, s. 167-185 Journal article (peer-reviewed)abstract Nomenclatural type definitions are one of the most important concepts in biological nomenclature. Being physical objects that can be re-studied by other researchers, types permanently link taxonomy (an artificial agreement to classify biological diversity) with nomenclature (an artificial agreement to name biological diversity). Two proposals to amend the International Code of Nomenclature for algae, fungi, and plants (ICN), allowing DNA sequences alone (of any region and extent) to serve as types of taxon names for voucherless fungi (mainly putative taxa from environmental DNA sequences), have been submitted to be voted on at the 11th International Mycological Congress (Puerto Rico, July 2018). We consider various genetic processes affecting the distribution of alleles among taxa and find that alleles may not consistently and uniquely represent the species within which they are contained. Should the proposals be accepted, the meaning of nomenclatural types would change in a fundamental way from physical objects as sources of data to the data themselves. Such changes are conducive to irreproducible science, the potential typification on artefactual data, and massive creation of names with low information content, ultimately causing nomenclatural instability and unnecessary work for future researchers that would stall future explorations of fungal diversity. We conclude that the acceptance of DNA sequences alone as types of names of taxa, under the terms used in the current proposals, is unnecessary and would not solve the problem of naming putative taxa known only from DNA sequences in a scientifically defensible way. As an alternative, we highlight the use of formulas for naming putative taxa (candidate taxa) that do not require any modification of the ICN.
2.	Otterbeck, Jonas, et al. (author) Concluding Remarks : Researching Music Censorship in Perspective 2017 In: Researching Music Censorship. - 9781443886178 ; , s. 312-321 Book chapter (peer-reviewed)
3.	Andersen, Felicie F., et al. (author) Assembly and structural analysis of a covalently closed nano-scale DNA cage 2008 In: Nucleic Acids Research. - : Oxford University Press (OUP). - 0305-1048 .- 1362-4962. ; 36:4, s. 1113-1119 Journal article (peer-reviewed)abstract The inherent properties of DNA as a stable polymer with unique affinity for partner mols. detd. by the specific Watson-Crick base pairing makes it an ideal component in self-assembling structures. This has been exploited for decades in the design of a variety of artificial substrates for investigations of DNA-interacting enzymes. More recently, strategies for synthesis of more complex two-dimensional (2D) and 3D DNA structures have emerged. However, the building of such structures is still in progress and more experiences from different research groups and different fields of expertise are necessary before complex DNA structures can be routinely designed for the use in basal science and/or biotechnol. Here we present the design, construction and structural anal. of a covalently closed and stable 3D DNA structure with the connectivity of an octahedron, as defined by the double-stranded DNA helixes that assembles from eight oligonucleotides with a yield of .apprx.30%. As demonstrated by Small Angle X-ray Scattering and cryo-Transmission Electron Microscopy analyses the eight-stranded DNA structure has a central cavity larger than the apertures in the surrounding DNA lattice and can be described as a nano-scale DNA cage, Hence, in theory it could hold proteins or other bio-mols. to enable their investigation in certain harmful environments or even allow their organization into higher order structures.
4.	Hulva, Jan, et al. (author) Adsorption of CO on the Fe3O4(001) Surface 2018 In: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 122:2, s. 721-729 Journal article (peer-reviewed)abstract The interaction of CO with the Fe3O4(001)-(√2 × √2)R45° surface was studied using temperature-programmed desorption (TPD), scanning tunneling microscopy (STM), and X-ray photoelectron spectroscopy (XPS), the latter both under ultrahigh vacuum (UHV) conditions and in CO pressures up to 1 mbar. In general, the CO-Fe3O4 interaction is found to be weak. The strongest adsorption occurs at surface defects, leading to small TPD peaks at 115, 130, and 190 K. Desorption from the regular surface occurs in two distinct regimes. For coverages up to two CO molecules per (√2 × √2)R45° unit cell, the desorption maximum shows a large shift with increasing coverage, from initially 105 to 70 K. For coverages between 2 and 4 molecules per (√2 × √2)R45° unit cell, a much sharper desorption feature emerges at ∼65 K. Thermodynamic analysis of the TPD data suggests a phase transition from a dilute 2D gas into an ordered overlayer with CO molecules bound to surface Fe3+ sites. XPS data acquired at 45 K in UHV are consistent with physisorption. Some carbon-containing species are observed in the near-ambient-pressure XPS experiments at room temperature but are attributed to contamination and/or reaction with CO with water from the residual gas. No evidence was found for surface reduction or carburization by CO molecules.
5.	Koro, Catalin, et al. (author) Carbamylation of immunoglobulin abrogates activation of the classical complement pathway 2014 In: European Journal of Immunology. - : Wiley. - 1521-4141 .- 0014-2980. ; 44:11, s. 3403-3412 Journal article (peer-reviewed)abstract Post-translational modifications of proteins significantly affect their structure and function. The carbamylation of positively charged lysine residues to form neutral homoitrulline occurs primarily under inflammatory conditions through myeloperoxidase-dependent cyanate (CNO-) formation. We analyzed the pattern of human IgG(1) carbamylation under inflammatory conditions and the effects that this modification has on the ability of antibodies to trigger complement activation via the classical pathway. We found that the lysine residues of IgG(1) are rapidly modified after brief exposure to CNO-. Interestingly, modifications were not random, but instead limited to only few lysines within the hinge area and the N-terminal fragment of the CH2 domain. A complement activation assay combined with mass spectrometry analysis revealed a highly significant inverse correlation between carbamylation of several key lysine residues within the hinge region and N-terminus of the CH2 domain and the proper binding of C1q to human IgG(1) followed by subsequent complement activation. This severely hindered complement-dependent cytotoxicity of therapeutic IgG(1). The reaction can apparently occur in vivo, as we found carbamylated antibodies in synovial fluid from rheumatoid arthritis patients. Taken together, our data suggest that carbamylation has a profound impact on the complement-activating ability of IgG(1) and reveals a pivotal role for previously uncharacterized lysine residues in this process.
6.	Lenhoff, Stig, et al. (author) Intensive therapy for multiple myeloma in patients younger than 60 years. Long-term results focusing on the effect of the degree of response on survival and relapse pattern after transplantation 2006 In: Haematologica. - 0390-6078 .- 1592-8721. ; 91:9, s. 1228-1233 Journal article (peer-reviewed)abstract Background and Objectives. From 1994 to 1997 we conducted a population-based, prospective study on intensive therapy in newly diagnosed symptomatic myeloma patients younger than 60 years, comparing their survival to that of a conventionally treated historic population. Long-term results are presented, including the impact of the degree of response on survival and relapse pattern after transplantation. Design and Methods. The prospective population was formed of 397 patients and the historic population of 313 patients. Both populations were calculated to comprise more than 75% of the expected number of new cases. Results. After a median follow-up of 7 years survival was longer in the prospective population than in the historic one (median 60 versus 39 months; p=0.0002). When comparing only patients eligible for intensive therapy the median survival was 63 versus 44 months (p < 0.0001). Attaining a complete response was associated with prolonged event-free survival but not overall survival. The pattern of relapse after transplantation was heterogeneous but could be divided into four major groups; insidious, classical, plasmacytoma form and transformed disease. The median survival after relapse was 29 months. The relapse pattern and time to relapse predicted outcome. Patients relapsing with an insidious or classical form of disease with skeletal events only, or after a long lasting first response were likely to respond well to conventional salvage therapy. In contrast, relapse with multiple symptoms, transformed disease or a short duration of first response implied bad prognosis. Interpretation and conclusions. The relapse pattern after autologous transplantation is heterogeneous and response to salvage therapy is variable. The degree of response and event-free survival after transplantation are not reliable surrogate markers for survival.
7.	Näslund, Jens-Ove, et al. (author) Fennoscandian paleo-environment and ice sheet dynamics during Marine Isotope Stage (MIS) 3 : Report of a workshop held September 20–21, 2007 in Stockholm, Sweden 2008 Reports (other academic/artistic)
8.	Snezhkova, Olesia, et al. (author) Nature of the bias-dependent symmetry reduction of iron phthalocyanine on Cu(111) 2015 In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 92:7 Journal article (peer-reviewed)abstract Subtle changes in the geometric and electronic properties of supported molecules, with a potential impact on the functioning of molecular devices, can typically be imaged by scanning probe microscopy, but their exact origin and nature often remain unclear. Here we show explicitly that the symmetry reduction of iron phthalocyanine upon adsorption on Cu(111) can be observed not only in scanning tunneling microscopy, but also in core-level spectroscopy, and that it is related to nonisotropic charge transfer into the two principal molecular axes, but in combination with topographic influences.
9.	Agåker, Marcus, et al. (author) A five-axis parallel kinematic mirror unit for soft X-ray beamlines at MAX IV 2020 In: Journal of Synchrotron Radiation. - : INT UNION CRYSTALLOGRAPHY. - 0909-0495 .- 1600-5775. ; 27, s. 262-271 Journal article (peer-reviewed)abstract With the introduction of the multi-bend achromats in the new fourth-generation storage rings the emittance has decreased by an order of magnitude resulting in increased brightness. However, the higher brightness comes with smaller beam sizes and narrower radiation cones. As a consequence, the requirements on mechanical stability regarding the beamline components increases. Here an innovative five-axis parallel kinematic mirror unit for use with soft X-ray beamlines using off-axis grazing-incidence optics is presented. Using simulations and measurements from the HIPPIE beamline at the MAX IV Laboratory it is shown that it has no Eigen frequencies below 90 Hz. Its positioning accuracy is better than 25 nm linearly and 17-35 mu rad angularly depending on the mirror chamber dimensions.
10.	Alm Rosenblad, Magnus, 1957, et al. (author) SRPDB: Signal Recognition Particle Database 2003 In: Nucleic Acids Research. - 0305-1048. ; 31:1, s. 363-4 Journal article (peer-reviewed)abstract The Signal Recognition Particle Database (SRPDB) at http://psyche.uthct.edu/dbs/SRPDB/SRPDB.html and http://bio.lundberg.gu.se/dbs/SRPDB/SRPDB.html assists in the better understanding of the structure and function of the signal recognition particle (SRP), a ribonucleoprotein complex that recognizes signal sequences as they emerge from the ribosome. SRPDB provides alphabetically and phylogenetically ordered lists of SRP RNA and SRP protein sequences. The SRP RNA alignment emphasizes base pairs supported by comparative sequence analysis to derive accurate SRP RNA secondary structures for each species. This release includes a total of 181 SRP RNA sequences, 7 protein SRP9, 11 SRP14, 31 SRP19, 113 SRP54 (Ffh), 9 SRP68 and 12 SRP72 sequences. There are 44 new sequences of the SRP receptor alpha subunit and its FtsY homolog (a total of 99 entries). Additional data are provided for polypeptides with established or potential roles in SRP-mediated protein targeting, such as the beta subunit of SRP receptor, Flhf, Hbsu and cpSRP43. Also available are motifs for the identification of new SRP RNA sequences, 2D representations, three-dimensional models in PDB format, and links to the high-resolution structures of several SRP components. New to this version of SRPDB is the introduction of a relational database system and a SRP RNA prediction server (SRP-Scan) which allows the identification of SRP RNAs within genome sequences and also generates secondary structure diagrams.
11.	Arman, Alif, et al. (author) Adsorption of hydrogen on stable and metastable Ir(100) surfaces 2017 In: Surface Science. - : Elsevier BV. - 0039-6028. ; 656, s. 66-76 Journal article (other academic/artistic)abstract Using the combination of high resolution core level spectroscopy and density functional theory we present adetailed spectroscopic study for all clean and hydrogen covered phases of Ir(100). The results are complementedby an investigation of the hydrogen desorption process from various phases using temperature programmeddesorption spectroscopy and scanning tunneling microscopy. In total, all experimentally determined core levelshifts match very well with those predicted by density functional theory based on established structural models.In particular, we find for the (bridge site) adsorption on the unreconstructed 1×1 phase that the initial core levelshift of surface Ir atoms is altered by +0.17 eV for each Ir–H bond formed. In the submonolayer regime we findevidence for island formation at low temperatures. For the H-induced deconstructed 5×1-H phase we identifyfour different surface core level shifts with two of them being degenerate. Finally, for the reconstructed 5×1-hexphase also four surface components are identified, which undergo a rather rigid core level shift of +0.15 eV uponhydrogen adsorption suggesting a similarly homogeneous charge transfer to all Ir surface atoms.Thermodesorption experiments for the 5×1-H phase reveal two different binding states for hydrogenindependent of the total coverage. We conclude that the surface always separates into patches of fully covereddeconstructed and uncovered reconstructed phases. We could also show by tunneling microscopy that with thedesorption of the last hydrogen atom from the deconstructed unit cell the surface instantaneously reverts intothe reconstructed state. Eventually, we could determine the saturation coverage upon molecular adsorption forall phases to be θmax = 1.0 ML1×1−H , θ = 0.8 ML max5×1−H , and θ ≥ 1.0 ML max5×1−hex−H .
12.	Arman, Alif, et al. (author) Co3O4(100) films grown on Ag(100): Structure and chemical properties 2017 In: Surface Science. - : Elsevier BV. - 0039-6028. ; 657, s. 90-95 Journal article (peer-reviewed)abstract Spinel type Co3O4(100) is successfully grown on Ag(100) at ultrahigh vacuum conditions and its structure, electronic and chemical properties are compared with those of Co3O4(111) grown on Ir(100). We find that the Co3O4(100) is unreconstructed. In contrast to the defect free Co3O4(111) surface the Co3O4(100) surface contains a high concentration of defects that we assign to subsurface cation vacancies analogous to those observed for Fe3O4(100). Our photoemission and absorption spectroscopy experiments reveal a very similar electronic structure of the Co3O4(111) and Co3O4(100) surfaces. The similar electronic structure of the two surfaces is reflected in the CO adsorption properties at low temperatures, as we observe adsorption of molecular CO as well as the formation of carbonate (CO3) species on both surfaces upon CO exposure at 85 K.
13.	Ataman, Evren, et al. (author) Adsorption of L-cysteine on rutile TiO2(110) 2011 In: Surface Science. - : Elsevier BV. - 0039-6028. ; 605:1-2, s. 179-186 Journal article (peer-reviewed)abstract We have used X-ray photoelectron spectroscopy to study the adsorption of L-cysteine on a rutile TiO2(110) surface at room temperature and -65 degrees C. For the molecules in direct contact with the surface our results suggest that the molecules bind dissociatively to the fivefold-coordinated Ti atoms of the surface through their deprotonated carboxylic groups. A second, dissociative interaction occurs between the molecular thiol groups and the surface. It is attributed to a dissociative bond to the bridging oxygen vacancies. Most likely, the thiol groups are deprotonated and a bond is formed between the thiolates and defects. In an alternative scenario, the C-S bond is cleaved and atomic sulfur binds to the defects. With regard to the molecular amino groups, they remain neutral at the lowest investigated coverages (0.3-0.5 ML), but already starting from around 0.7 ML nominal coverage protons are being transferred to them. The fraction of protonated amino groups increases with coverage and becomes dominating in multilayers prepared at room temperature and -65 degrees C. In these multilayers the carboxylic groups are deprotonated. (C) 2010 Elsevier B.V. All tights reserved.
14.	Ataman, Evren, et al. (author) Modification of the Size of Supported Clusters by Coadsorption of an Organic Compound: Gold and l-Cysteine on Rutile TiO(2)(110). 2011 In: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 27:18, s. 11466-11474 Journal article (peer-reviewed)abstract Using X-ray photoelectron spectroscopy we studied the coadsorption of the amino acid l-cysteine and gold on a rutile TiO(2)(110) surface under ultrahigh vacuum conditions. Irrespective of the deposition order, i.e., irrespective of whether l-cysteine or gold is deposited first, the primary interaction between l-cysteine and the gold clusters formed at the surface takes place through the deprotonated thiol group of the molecule. The deposition order, however, has a profound influence on the size of the gold clusters as well as their location on the surface. If l-cysteine is deposited first the clusters are smaller by a factor two to three compared to gold deposited onto the pristine TiO(2)(110) surface and then covered by l-cysteine. Further, in the former case the clusters cover the molecules and thus form the outermost layer of the sample. We also find that above a minimum gold cluster size the gold cluster/l-cysteine bond is stronger than the l-cysteine/surface bridging oxygen vacancy bond, which, in turn, is stronger than the gold cluster/vacancy bond.
15.	Backrud, Marie, 1971- (author) Cluster Observations and Theoretical Explanations of Broadband Waves in the Auroral Region 2005 Doctoral thesis (other academic/artistic)abstract Broadband extremely low-frequency wave emissions below the ion plasma frequency have been observed by a number of spacecraft and rockets on auroral field lines. The importance of these broadband emissions for transverse ion heating and electron acceleration in the auroral regions is now reasonably well established. However, the exact mechanism(s) for mediating this energy transfer and the wave mode(s) involved are not well known. In this thesis we focus on the identification of broadband waves by different methods. Two wave analysis methods, involving different approximations and assumptions, give consistent results concerning the wave mode identification. We find that much of the broadband emissions can be identified as a mixture of ion acoustic, electrostatic ion cyclotron and, ion Bernstein waves, which all can be described as different parts of the same dispersion surface in the linear theory of waves in homogeneous plasma. A new result is that ion acoustic waves occur on auroral magnetic field lines. These are found in relatively small regions interpreted as acceleration regions without cold (tens of eV) electrons.From interferometry we also determine the phase velocity and k vector for parallel and oblique ion acoustic waves. The retrieved characteristic phase velocity is of the order of the ion acoustic speed and larger than the thermal velocity of the protons. The typical wavelength is around the proton gyro radius and always larger than the Debye length which is consistent with ion acoustic waves. We have observed quasi-static parallel electric fields associated with the ion acoustic waves in regions with large-scale currents. Waves, in particular ion acoustic waves, can create an anomalous resistivity due to wave-particle interaction when electrons are retarded or trapped by the electric wave-field. To maintain the large-scale current, a parallel electric field is set up, which then can accelerate a second electron population to high velocities.
16.	Blauenfeldt, Rolf Ankerlund, et al. (author) Remote Ischemic Conditioning for Acute Stroke : The RESIST Randomized Clinical Trial 2023 In: JAMA. - 0098-7484. ; 330:13, s. 1236-1246 Journal article (peer-reviewed)abstract Importance: Despite some promising preclinical and clinical data, it remains uncertain whether remote ischemic conditioning (RIC) with transient cycles of limb ischemia and reperfusion is an effective treatment for acute stroke. Objective: To evaluate the effect of RIC when initiated in the prehospital setting and continued in the hospital on functional outcome in patients with acute stroke. Design, Setting, and Participants: This was a randomized clinical trial conducted at 4 stroke centers in Denmark that included 1500 patients with prehospital stroke symptoms for less than 4 hours (enrolled March 16, 2018, to November 11, 2022; final follow-up, February 3, 2023). Intervention: The intervention was delivered using an inflatable cuff on 1 upper extremity (RIC cuff pressure, ≤200 mm Hg [n = 749] and sham cuff pressure, 20 mm Hg [n = 751]). Each treatment application consisted of 5 cycles of 5 minutes of cuff inflation followed by 5 minutes of cuff deflation. Treatment was started in the ambulance and repeated at least once in the hospital and then twice daily for 7 days among a subset of participants. Main Outcomes and Measures: The primary end point was improvement in functional outcome measured as a shift across the modified Rankin Scale (mRS) score (range, 0 [no symptoms] to 6 [death]) at 90 days in the target population with a final diagnosis of ischemic or hemorrhagic stroke. Results: Among 1500 patients who were randomized (median age, 71 years; 591 women [41%]), 1433 (96%) completed the trial. Of these, 149 patients (10%) were diagnosed with transient ischemic attack and 382 (27%) with a stroke mimic. In the remaining 902 patients with a target diagnosis of stroke (737 [82%] with ischemic stroke and 165 [18%] with intracerebral hemorrhage), 436 underwent RIC and 466 sham treatment. The median mRS score at 90 days was 2 (IQR, 1-3) in the RIC group and 1 (IQR, 1-3) in the sham group. RIC treatment was not significantly associated with improved functional outcome at 90 days (odds ratio [OR], 0.95; 95% CI, 0.75 to 1.20, P =.67; absolute difference in median mRS score, -1; -1.7 to -0.25). In all randomized patients, there were no significant differences in the number of serious adverse events: 169 patients (23.7%) in the RIC group with 1 or more serious adverse events vs 175 patients (24.3%) in the sham group (OR, 0.97; 95% CI, 0.85 to 1.11; P =.68). Upper extremity pain during treatment and/or skin petechia occurred in 54 (7.2%) in the RIC group and 11 (1.5%) in the sham group. Conclusions and Relevance: RIC initiated in the prehospital setting and continued in the hospital did not significantly improve functional outcome at 90 days in patients with acute stroke. Trial Registration: ClinicalTrials.gov Identifier: NCT03481777.
17.	Boix, Virgínia, et al. (author) Area-selective Electron-beam induced deposition of Amorphous-BNx on graphene 2021 In: Applied Surface Science. - : Elsevier BV. - 0169-4332. ; 557, s. 149806-149806 Journal article (peer-reviewed)abstract Thin, stable and inert dielectric spacers are essential for manufacturing electronic devices based on 2D materials. However, direct synthesis on top of 2D materials is difficult due to their inert nature. In this work, we studied how an electron beam induces fragmentation of borazine and enables spatially confined synthesis of amorphous-BNx on graphene at room temperature. Using a combination of X-ray Photoelectron Spectroscopy, Low Energy Electron Microscopy, and Scanning Tunneling Microscopy we studied the morphology of the heterostructure, its chemical composition, and finally its temperature evolution. We find that electron-beam induced deposition starts by the binding of heavily fragmentized borazine, including atomic boron, followed by the growth of a multilayer with a 1:0.7 B:N ratio. The final structure exhibits a thermal stability up to 1400 K and ~ 50 nm spatial control provided by the electron beam. Our studies provide surface science insight into the use of electron beams for synthesis and lateral control of stable and inert layers in 2D heterostructures.
18.	Boix, Virginia, et al. (author) Following the Kinetics of Undercover Catalysis with APXPS and the Role of Hydrogen as an Intercalation Promoter 2022 In: ACS Catalysis. - : American Chemical Society (ACS). - 2155-5435. ; 12:16, s. 9897-9907 Journal article (peer-reviewed)abstract While improved catalytic properties of many surfaces covered by two-dimensional materials have been demonstrated, a detailed in situ picture of gas delivery, undercover reaction, and product removal from the confined space is lacking. Here, we demonstrate how a combination of gas pulses with varying compositions and time-resolved ambient pressure photoelectron spectroscopy can be used to obtain such knowledge. This approach allows us to sequentially form and remove undercover reaction products, in contrast to previous work, where co-dosing of reactant gases was used. In more detail, we study CO and H2 oxidation below oxygen-intercalated graphene flakes partially covering an Ir(111) surface. We show that hydrogen rapidly mixes into a p(2 × 1)-O structure below the graphene flakes and converts it into a dense OH-H2O phase. In contrast, CO exposure only leads to oxygen removal from the confined space and little CO intercalation. Finally, our study shows that H2 mixed into CO pulses can be used as a promoter to change the undercover chemistry. Their combined exposure leads to the formation of OH-H2O below the flakes, which, in turn, unbinds the flakes for enough time for CO to intercalate, resulting in a CO structure stable only in coexistence with the OH-H2O phase. Altogether, our study proves that promoter chemistry in the form of adding trace gases to the gas feed is essential to consider for undercover reactions.
19.	Boix, Virginia, et al. (author) Graphene as an Adsorption Template for Studying Double Bond Activation in Catalysis 2022 In: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 126:33, s. 14116-14124 Journal article (peer-reviewed)abstract Hydrogenated graphene (H-Gr) is an extensively studied system not only because of its capabilities as a simplified model system for hydrocarbon chemistry but also because hydrogenation is a compelling method for Gr functionalization. However, knowledge of how H-Gr interacts with molecules at higher pressures and ambient conditions is lacking. Here we present experimental and theoretical evidence that room temperature O2exposure at millibar pressures leads to preferential removal of H dimers on H-functionalized graphene, leaving H clusters on the surface. Our density functional theory (DFT) analysis shows that the removal of H dimers is the result of water or hydrogen peroxide formation. For water formation, we show that the two H atoms in the dimer motif attack one end of the physisorbed O2molecule. Moreover, by comparing the reaction pathways in a vacuum with the ones on free-standing graphene and on the graphene/Ir(111) system, we find that the main role of graphene is to arrange the H atoms in geometrical positions, which facilitates the activation of the O═O double bond.
20.	Buchert, Stephan C., et al. (author) First results from the Langmuir probes on the Swarm satellites 2014 In: 2014 XXXITH URSI General Assembly And Scientific Symposium (URSI GASS). - 9781467352253 Conference paper (peer-reviewed)
21.	Dines Knudsen, Jan, et al. (author) NADH-dependent biosensor in Saccharomyces cerevisiae: principle and validation at the single cell level. 2014 In: AMB Express. - : Springer Science and Business Media LLC. - 2191-0855. ; 4 Journal article (peer-reviewed)abstract A reporter system was constructed to measure perturbations in the NADH/NAD(+) co-factor balance in yeast, by using the green fluorescent protein gene under the control of the GPD2 promoter that is induced under conditions of excess of NADH. High fluorescence levels were obtained in a glycerol 3-phosphate dehydrogenase double deletion strain (gpd1Δgpd2Δ), which is deficient in the ability to regenerate NAD(+) via glycerol formation. The responsiveness of the reporter system to externally induced perturbations in NADH oxidation was also evaluated in the gpd1Δgpd2Δ strain background by addition of acetoin, as well as by introduction of a set of heterologous xylose reductases (XRs) having different selectivities for NADH. Addition of acetoin during cell proliferation under oxygen-limited conditions resulted in a more than 2-fold decrease in mean fluorescence intensity as compared to the control experiment. Strains carrying XRs with different selectivities for NADH could be distinguished at the single cell level, so that the XR with the highest selectivity for NADH displayed the lowest fluorescence. In conclusion, the designed system successfully allowed for monitoring perturbations in the cellular redox metabolism caused by environmental changes, or by heterologous gene expression. The reporter system displayed high resolution in distinguishing cytosolic NADH oxidation capacity and hence has potential to be used for high-throughput screening based on the fluorescence of single cells.
22.	Doeser, Fredrik (author) In Search of Security After the Collapse of the Soviet Union : Foreign Policy Change in Denmark, Finland and Sweden, 1988-1993 2008 Doctoral thesis (other academic/artistic)abstract The aim of this study is to explain the evolution of foreign policy in Denmark, Finland and Sweden with regard to Western security cooperation between 1988 and 1993. The study sets out to test two theoretical perspectives on the security cooperation policies of these three small states. The external political perspective is based on the idea that foreign policy is determined by the challenges of a state’s external political environment. The domestic political perspective is based on the idea that phenomena at the domestic level of the state have an impact on how governments cope with external constraints. The primary theoretical ambition is to integrate the findings from these two analyses in order to further an understanding of the mechanisms of foreign policy change in small states.In order to study the relationship between the environment and foreign policy change, the author applies a perceptual approach, which means that his intention is to explain foreign policy action on the basis of the perceptions actors have of the environment.The author draws a number of conclusions with regard to the mechanisms of foreign policy change. First, a perceptual approach is needed in order to analyze a state’s specific responses to international political change. Second, domestic factors are not only important for foreign policy in general but also for the evolution of security cooperation policy in small states under conditions of fundamental shift in the international system. Third, it is possible to attribute some degree of relative explanatory power to external factors and to assign a range of different roles to domestic factors. Fourth, governments of Western democratic small states pay relatively equal attention to external and domestic considerations when making their foreign policies. However, depending on the situation, the relative potency of external and domestic factors can vary.
23.	Fernandes, V. R., et al. (author) Reversed Hysteresis during CO Oxidation over Pd75Ag25(100) 2016 In: ACS Catalysis. - : American Chemical Society (ACS). - 2155-5435. ; 6:7, s. 4154-4161 Journal article (peer-reviewed)abstract CO oxidation over Pd(100) and Pd75Ag25(100) has been investigated by a combination of near-ambient pressure X-ray photoelectron spectroscopy, quadrupole mass spectrometry, density functional theory calculations, and microkinetic modeling. For both surfaces, hysteresis is observed in the CO2 formation during the heating and cooling cycles. Whereas normal hysteresis with light-off temperature higher than extinction temperature is present for Pd(100), reversed hysteresis is observed for Pd75Ag25(100). The reversed hysteresis can be explained by dynamic changes in the surface composition. At the beginning of the heating ramp, the surface is rich in palladium, which gives a CO coverage that poisons the surface until the desorption rate becomes sufficiently high. The thermodynamic preference for an Ag-rich surface in the absence of adsorbates promotes diffusion of Ag from the bulk to the surface as CO desorbs. During the cooling ramp, an appreciable surface coverage is reached at temperatures too low for efficient diffusion of Ag back into the bulk. The high concentration of Ag in the surface leads to a high extinction temperature and, consequently, the reversed hysteresis.
24.	Ferstl, P., et al. (author) Adsorption and Activation of CO on Co3O4(111) Thin Films 2015 In: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 119:29, s. 16688-16699 Journal article (peer-reviewed)abstract To explore the catalytic properties of cobalt oxide at the atomic level, we have studied the interaction of CO and O-2 with well-ordered Co3O4(111) thin films using scanning tunneling microscopy (STM), high-resolution X-ray photoelectron spectroscopy (HR-XPS), infrared reflection absorption spectroscopy (IRAS), and temperature-programmed desorption spectroscopy (TPD) under ultrahigh vacuum (UHV) conditions. At low coverage and temperature, CO binds to surface Co2+ ions on the (111) facets. At larger exposure, a compressed phase is formed in which additional CO is located at sites in between the Co2+ ions. In addition, a bridging carbonate species forms that is associated with defects such as step edges of Co3O4(111) terraces or the side facets of the (111) oriented grains. Preadsorbed oxygen neither affects CO adsorption at low coverage nor the formation of the surface carbonate, but it blocks formation of the high coverage CO phase. Desorption of the molecularly bound CO occurs up to 180 K, whereas the surface carbonate decomposes in a broad temperature range up to 400 K under the release of CO and, to a lesser extent, of CO2. Upon strong loss of crystalline oxygen, the Co3O4 grains eventually switch to the CoO rocksalt structure.
25.	Gajhede-Knudsen, Mariann, et al. (author) Recurrence of Achilles tendon injuries in elite male football players is more common after early return to play: an 11-year follow-up of the UEFA Champions League injury study 2013 In: British Journal of Sports Medicine. - : BMJ Publishing Group. - 0306-3674 .- 1473-0480. ; 47:12, s. 763-768 Journal article (peer-reviewed)abstract Background There is limited information about Achilles tendon disorders in professional football. less thanbrgreater than less thanbrgreater thanAims To investigate the incidence, injury circumstances, lay-off times and reinjury rates of Achilles tendon disorders in male professional football. less thanbrgreater than less thanbrgreater thanMethods A total of 27 clubs from 10 countries and 1743 players have been followed prospectively during 11 seasons between 2001 and 2012. The team medical staff recorded individual player exposure and time-loss injuries. less thanbrgreater than less thanbrgreater thanResults A total of 203 (2.5% of all injuries) Achilles tendon disorders were registered. A majority (96%) of the disorders were tendinopathies, and nine were partial or total ruptures. A higher injury rate was found during the preseason compared with the competitive season, 0.25 vs 0.18/1000 h (rate ratio (RR) 1.4, 95% CI 1.1 to 2.0; p=0.027). The mean lay-off time for Achilles tendinopathies was 23 +/- 37 (median=10, Q(1)=4 and Q(3)=24) days, while a rupture of the Achilles tendon, on average, caused 161 +/- 65 (median=169, Q(1)=110 and Q(3)=189) days of absence. Players with Achilles tendon disorders were significantly older than the rest of the cohort, with a mean age of 27.2 +/- 4 years vs 25.6 +/- 4.6 years (pandlt;0.001). 27% of all Achilles tendinopathies were reinjuries. A higher reinjury risk was found after short recovery periods (31%) compared with longer recovery periods (13%) (RR 2.4, 95% CI 2.1 to 2.8; pandlt;0.001). less thanbrgreater than less thanbrgreater thanConclusions Achilles tendon disorders account for 3.8% of the total lay-off time and are more common in older players. Recurrence is common after Achilles tendinopathies and the reinjury risk is higher after short recovery periods.
26.	Gerber, Timm, et al. (author) CO-Induced Smoluchowski Ripening of Pt Cluster Arrays on the Graphene/Ir(111) Moire 2013 In: ACS Nano. - : American Chemical Society (ACS). - 1936-086X .- 1936-0851. ; 7:3, s. 2020-2031 Journal article (peer-reviewed)abstract Regular Pt cluster arrays grown on the moire template formed by graphene on Ir(111) were tested for their stability with respect to CO gas exposure. Cluster stability and adsorption-Induced processes were analyzed as a function of cluster size, with In situ scanning tunneling microscopy and X-ray photoelectron spectroscopy. Small clusters containing fewer than 10 atoms were unstable upon CO adsorption. They sintered through Smoluchowski ripening-cluster diffusion and coalescence rather than the frequently reported Ostwald ripening mediated by metal-adsorbate complexes. Larger dusters remained immobile upon CO adsorption but became more three-dimensional. Careful analysis of the experimental data complemented by ab initio density functional theory calculations provides insight Into the origin of the CO-induced Pt cluster ripening and shape transformations.
27.	Gimsing, Peter, et al. (author) Effect of pamidronate 30 mg versus 90 mg on physical function in patients with newly diagnosed multiple myeloma (Nordic Myeloma Study Group): a double-blind, randomised controlled trial 2010 In: LANCET ONCOLOGY. - : Elsevier Science B.V., Amsterdam.. - 1470-2045 .- 1474-5488. ; 11:10, s. 973-982 Journal article (peer-reviewed)abstract Background Compared with placebo, prophylactic treatment with bisphosphonates reduces risk of skeletal events in patients with multiple myeloma. However, because of toxicity associated with long-term bisphosphonate treatment, establishing the lowest effective dose is important. This study compared the effect of two doses of pamidronate on health-related quality of life and skeletal morbidity in patients with newly diagnosed multiple myeloma. Methods This double-blind, randomised, phase 3 trial was undertaken at 37 clinics in Denmark, Norway, and Sweden. Patients with multiple myeloma who were starting antimyeloma treatment were randomly assigned in a 1:1 ratio to receive one of two doses of pamidronate (30 mg or 90 mg) given by intravenous infusion once a month for at least 3 years. Randomisation was done by use of a central, computerised minimisation system. Primary outcome was physical function after 12 months estimated by the European Organisation for Research and Treatment of Cancer (EORTC) QLQ-C30 questionnaire (scale 0-100). All patients who returned questionnaires at 12 months and were still on study treatment were included in the analysis of the primary endpoint. This study is registered with ClinicalTrials. gov, number NCT00376883. Findings From January, 2001, until August, 2005, 504 patients were randomly assigned to pamidronate 30 mg or 90 mg (252 in each group). 157 patients in the 90 mg group and 156 in the 30 mg group were included in the primary analysis. Mean physical function at 12 months was 66 points (95% CI 62.9-70.0) in the 90 mg group and 68 points (64.6-71.4) in the 30 mg group (95% CI of difference -6.6 to 3.3; p=0.52). Median time to first skeletal-related event in patients who had such an event was 9.2 months (8.1-10.7) in the 90 mg group and 10-2 months (7.3-14.0) in the 30 mg group (p=0.63). In a retrospective analysis, eight patients in the pamidronate 90 mg group developed osteonecrosis of the jaw compared with two patients in the 30 mg group. Interpretation Monthly infusion of pamidronate 30 mg should be the recommended dose for prevention of bone disease in patients with multiple myeloma.
28.	Gommenginger, Christine, et al. (author) SEASTAR: A mission to study ocean submesoscale dynamics and small-scale atmosphere-ocean processes in coastal, shelf and polar seas 2019 In: Frontiers in Marine Science. - : Frontiers Media SA. - 2296-7745. ; 6:JUL Journal article (other academic/artistic)abstract High-resolution satellite images of ocean color and sea surface temperature reveal an abundance of ocean fronts, vortices and filaments at scales below 10 km but measurements of ocean surface dynamics at these scales are rare. There is increasing recognition of the role played by small scale ocean processes in ocean-atmosphere coupling, upper-ocean mixing and ocean vertical transports, with advanced numerical models and in situ observations highlighting fundamental changes in dynamics when scales reach 1 km. Numerous scientific publications highlight the global impact of small oceanic scales on marine ecosystems, operational forecasts and long-term climate projections through strong ageostrophic circulations, large vertical ocean velocities and mixed layer re-stratification. Small-scale processes particularly dominate in coastal, shelf and polar seas where they mediate important exchanges between land, ocean, atmosphere and the cryosphere e.g. freshwater, pollutants. As numerical models continue to evolve towards finer spatial resolution and increasingly complex coupled atmosphere-wave-ice-ocean systems, modern observing capability lags behind, unable to deliver the high-resolution synoptic measurements of total currents, wind vectors and waves needed to advance understanding, develop better parameterizations and improve model validations, forecasts and projections. SEASTAR is a satellite mission concept that proposes to directly address this critical observational gap with synoptic two-dimensional imaging of total ocean surface current vectors and wind vectors at 1 km resolution and coincident directional wave spectra. Based on major recent advances in squinted along-track Synthetic Aperture Radar interferometry, SEASTAR is an innovative, mature concept with unique demonstrated capabilities, seeking to proceed towards spaceborne implementation within Europe and beyond.
29.	Grizolli, Walan, et al. (author) Use of astigmatic re-focusing at HP-XPS end-station 2013 In: 11th International Conference on Synchrotron Radiation Instrumentation (SRI 2012). - : IOP Publishing. - 1742-6596 .- 1742-6588. ; 425 Conference paper (peer-reviewed)abstract In this paper we present the refocusing optics for the new high pressure photoelectron spectroscopy (HP-XPS) branch line at MAX-lab, based on a plane grating monochromator with vertically collimated beam. For the HP-XPS instrument, the required spot size is dictated by the small geometric acceptance of the HP-XPS electron energy analyzer. Whereas a pair of bendable mirrors in a KB configuration has some advantages as refocusing elements, we have studied whether similar performance can be achieved with a single non-bendable mirror. In this solution, however, the need for strong horizontal magnification results in a strong vertical magnification and into a very asymmetric image, the height being just a fraction of the width. We have studied through an analytical geometrical model and ray tracing simulations the use of astigmatism to increase the vertical beam size up to the geometric acceptance of the detector. As a result the vertical beam size at sample plane is mostly determined by the photon angular distribution and is not dependent on the exit slit aperture size. In addition the vertical beam size can be controlled by the grating c(ff) parameter, making possible to adjust the photon density and minimize sample damage by the radiation.
30.	Grånäs, Elin, et al. (author) CO Intercalation of Graphene on Ir(111) in the Millibar Regime 2013 In: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 117:32, s. 16438-16447 Journal article (peer-reviewed)abstract Here we show that it is possible to intercalate CO under graphene grown on Ir(111) already at room temperature when CO pressures in the millibar regime are used. From the interplay of X-ray photoelectron spectroscopy and scanning tunneling microscopy we conclude that the intercalated CO adsorption structure is similar to the (3 root 3 X 3 root 3)R30 degrees) adsorption structure that is formed on Ir(111) upon exposure to similar to 1 mbar of CO. Further, density functional theory calculations reveal that the structural and electronic properties of CO-intercalated graphene are similar to p-doped freestanding graphene. Finally we characterize nonintercalated stripes and islands that we always observe in the CO-intercalated graphene. We observe these nonintercalated areas predominately in HCP and FCC areas near step edges and suggest that stress release in graphene is the driving force for their formation, while the weak chemical bonds in HCP and FCC areas are the reason for their area selectivity.
31.	Grånäs, Elin, et al. (author) Hydrogen intercalation under graphene on Ir(111) 2016 In: Surface Science. - : Elsevier BV. - 0039-6028. ; 651, s. 57-61 Journal article (peer-reviewed)abstract Using high resolution X-ray photoelectron spectroscopy and scanning tunneling microscopy we study the intercalation of hydrogen under graphene/Ir(111). The hydrogen intercalated graphene is characterized by a component in C 1s that is shifted −0.10 to −0.18 eV with respect to pristine graphene and a component in Ir 4f at 60.54 eV. The position of this Ir 4f component is identical to that of the Ir(111) surface layer with hydrogen atoms adsorbed, indicating that the atomic hydrogen adsorption site on bare Ir(111) and beneath graphene is the same. Based on co-existence of fully- and non-intercalated graphene, and the inability to intercalate a closed graphene film covering the entire Ir(111) surface, we conclude that hydrogen dissociatively adsorbs at bare Ir(111) patches, and subsequently diffuses rapidly under graphene. A likely entry point for the intercalating hydrogen atoms is identified to be where graphene crosses an underlying Ir(111) step.
32.	Grånäs, Elin, et al. (author) Oxygen Intercalation under Graphene on Ir(111): Energetics, Kinetics, and the Role of Graphene Edges. 2012 In: ACS Nano. - : American Chemical Society (ACS). - 1936-086X .- 1936-0851. Journal article (peer-reviewed)abstract Using X-ray photoemission spectroscopy (XPS) and scanning tunneling microscopy (STM) we resolve the temperature-, time-, and flake size-dependent intercalation phases of oxygen underneath graphene on Ir(111) formed upon exposure to molecular oxygen. Through the applied pressure of molecular oxygen the atomic oxygen created on the bare Ir terraces is driven underneath graphene flakes. The importance of substrate steps and of the unbinding of graphene flake edges from the substrate for the intercalation is identified. With the use of CO titration to selectively remove oxygen from the bare Ir terraces the energetics of intercalation is uncovered. Cluster decoration techniques are used as an efficient tool to visualize intercalation processes in real space.
33.	Grånäs, Elin, et al. (author) Water Chemistry beneath Graphene : Condensation of a Dense OH-H2O Phase under Graphene 2022 In: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 126:9, s. 4347-4354 Journal article (peer-reviewed)abstract Room temperature oxygen hydrogenation below graphene flakes supported by Ir(111) is investigated through a combination of X-ray photoelectron spectroscopy, scanning tunneling microscopy, and density functional theory calculations using an evolutionary search algorithm. We demonstrate how the graphene cover and its doping level can be used to trap and characterize dense mixed O-OH-H2O phases that otherwise would not exist. Our study of these graphene-stabilized phases and their response to oxygen or hydrogen exposure reveals that additional oxygen can be dissolved into them at room temperature creating mixed O-OH-H2O phases with an increased areal coverage underneath graphene. In contrast, additional hydrogen exposure converts the mixed O-OH-H2O phases back to pure OH-H2O with a reduced areal coverage underneath graphene.
34.	Hartl, Tobias, et al. (author) Carbon Embedding of Pt Cluster Superlattices Templated by Hexagonal Boron Nitride on Ir(111) 2021 In: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 125:42, s. 23435-23444 Journal article (peer-reviewed)abstract With the goal to delevop the fabrication of a new type of Pt-nanoparticle carbon-support electrocatalyst, we investigate the carbon embedding of Pt cluster superlattices grown on the moiré of a monolayer of hexagonal boron nitride (h-BN) on Ir(111). Our combined scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS) study establishes conformal C embedding of the Pt clusters on h-BN/Ir(111) without deterioration of superlattice order, preferential and strong binding of the embedding carbon to the Pt clusters, and upon annealing the formation of a homogeneous amorphous carbon (a-C) matrix. There are indications that while the a-C matrix and the Pt clusters bind strongly to each other, upon annealing both weaken their binding to h-BN.
35.	Hartl, Tobias, et al. (author) Cluster Superlattice Membranes 2020 In: ACS Nano. - : American Chemical Society (ACS). - 1936-086X .- 1936-0851. ; 14:10, s. 13629-13637 Journal article (peer-reviewed)abstract Cluster superlattice membranes consist of a two-dimensional hexagonal lattice of similar-sized nanoclusters sandwiched between single-crystal graphene and an amorphous carbon matrix. The fabrication process involves three main steps, the templated self-organization of a metal cluster superlattice on epitaxial graphene on Ir(111), conformal embedding in an amorphous carbon matrix, and subsequent lift-off from the Ir(111) substrate. The mechanical stability provided by the carbon-graphene matrix makes the membrane stable as a free-standing material and enables transfer to other substrates. The fabrication procedure can be applied to a wide variety of cluster materials and cluster sizes from the single-atom limit to clusters of a few hundred atoms, as well as other two-dimensional layer/host matrix combinations. The versatility of the membrane composition, its mechanical stability, and the simplicity of the transfer procedure make cluster superlattice membranes a promising material in catalysis, magnetism, energy conversion, and optoelectronics.
36.	Hebbeln, Dierk, et al. (author) Late Holocene coastal hydrographic and climate changes in the eastern North Sea 2006 In: The Holocene. - : SAGE Publications. - 0959-6836 .- 1477-0911. ; 16:7, s. 987-1001 Journal article (peer-reviewed)abstract We present a high-resolution palaeoenvironmental reconstruction covering the late Holocene from the Skagerrak and other sites in the North Sea area. The data, which are based on the analyses of marine sediment cores, reveal a marked environmental shift that took place between AD 700 and AD 1100, with the most pronounced changes occurring at AD 900. Both surface and bottom waters in the Skagerrak were subject to major circulation and productivity changes at this time due to an enhanced advection of Atlantic waters to the North Sea marking the beginning of the 'Mediaeval Warm Period' (MWP). The observed increase in bottom current strength is especially remarkable as there is hardly any comparable signal in the older part of the record going back to 1000 BC. At the transition to the 'Little Ice Age' (LIA) the bottom current strength remains at a high level, now probably forced by atmospheric circulation. Thus, despite opposite temperature forcing, these two consecutive climate scenarios are apparently able to generate distinctly stronger bottom currents in the Skagerrak than observed in the preceding 2000 years, and demonstrate the significance of climatic forcing in shaping the marine environment. Indeed, both the MWP and the LIA are reported as strong climatic signals in northwest Europe, being the warmest (except the late twentieth century) and coldest periods, respectively, during at least the last 2000 years.
37.	Herbig, Charlotte, et al. (author) Comment on "interfacial carbon nanoplatelet formation by ion irradiation of graphene on iridium(111)". 2015 In: ACS Nano. - : American Chemical Society (ACS). - 1936-086X .- 1936-0851. ; 9:5, s. 4664-4665 Journal article (peer-reviewed)
38.	Herbig, Charlotte, et al. (author) From Permeation to Cluster Arrays : Graphene on Ir(111) Exposed to Carbon Vapor 2017 In: Nano Letters. - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 17:5, s. 3105-3112 Journal article (peer-reviewed)abstract Our scanning tunneling microscopy and X-ray photoelectron spectroscopy experiments along with first-principles calculations uncover the rich phenomenology and enable a coherent understanding of carbon vapor interaction with graphene on Ir(111). At high temperatures, carbon vapor not only permeates to the metal surface but also densifies the graphene cover. Thereby, in addition to underlayer graphene growth, upon cool down also severe wrinkling of the densified graphene cover is observed. In contrast, at low temperatures the adsorbed carbon largely remains on top and self-organizes into a regular array of fullerene-like, thermally highly stable clusters that are covalently bonded to the underlying graphene sheet. Thus, a new type of predominantly sp2-hybridized nanostructured and ultrathin carbon material emerges, which may be useful to encage or stably bind metal in finely dispersed form.
39.	Herbig, Charlotte, et al. (author) Xe irradiation of graphene on Ir(111): From trapping to blistering 2015 In: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 92:8 Journal article (peer-reviewed)abstract Using x-ray photoelectron spectroscopy, thermal desorption spectroscopy, and scanning tunneling microscopy, we show that upon keV Xe+ irradiation of graphene on Ir(111), Xe atoms are trapped under the graphene. Upon annealing, aggregation of Xe leads to graphene bulges and blisters. The efficient trapping is an unexpected and remarkable phenomenon given the absence of chemical binding of Xe to Ir and to graphene, the weak interaction of a perfect graphene layer with Ir(111), as well as the substantial damage to graphene due to irradiation. By combining molecular dynamics simulations and density functional theory calculations with our experiments, we uncover the mechanism of trapping. We describe ways to avoid blister formation during graphene growth, and also demonstrate how ion implantation can be used to intentionally create blisters without introducing damage to the graphene layer. Our approach may provide a pathway to synthesize new materials at a substrate-2D material interface or to enable confined reactions at high pressures and temperatures.
40.	Isvoranu, Cristina, et al. (author) Adsorption of ammonia on multilayer iron phthalocyanine. 2011 In: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 134:11 Journal article (peer-reviewed)abstract The adsorption of ammonia on multilayers of well-ordered, flat-lying iron phthalocyanine (FePc) molecules on a Au(111) support was investigated by x-ray photoelectron spectroscopy. We find that the electron-donating ammonia molecules coordinate to the metal centers of iron phthlalocyanine. The coordination of ammonia induces changes of the electronic structure of the iron phthalocyanine layer, which, in particular, lead to a modification of the FePc valence electron spin.
41.	Isvoranu, Cristina, et al. (author) Ammonia adsorption on iron phthalocyanine on Au(111): Influence on adsorbate-substrate coupling and molecular spin. 2011 In: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 134:11 Journal article (peer-reviewed)abstract The adsorption of ammonia on Au(111)-supported monolayers of iron phthalocyanine has been investigated by x-ray photoelectron spectroscopy, x-ray absorption spectroscopy, and density functional theory calculations. The ammonia-induced changes of the x-ray photoemission lines show that a dative bond is formed between ammonia and the iron center of the phthalocyanine molecules, and that the local spin on the iron atom is quenched. This is confirmed by density functional theory, which also shows that the bond between the iron center of the metalorganic complex and the Au(111) substrate is weakened upon adsorption of ammonia. The experimental results further show that additional adsorption sites exist for ammonia on the iron phthalocyanine monolayer.
42.	Isvoranu, Cristina, et al. (author) Comparison of the Carbonyl and Nitrosyl Complexes Formed by Adsorption of CO and NO on Mono layers of Iron Phthalocyanine on Au(111) 2011 In: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 115:50, s. 24718-24727 Journal article (peer-reviewed)abstract The interaction between monolayers of iron phthalocyanine on a Au(111) support and carbon monoxide and nitric oxide is studied by X-ray photoelectron spectroscopy and density functional theory calculations. We find several carbon monoxide and nitric oxide adsorbate species, and in particular species that bind to the iron ions of the phthalocyanine compound. The formation of phthalocyanine carbonyl and nitrosyl complexes leads to a redistribution of the electrons in the iron 3d levels resulting in a change of the spin state. Further, the adsorption results in an electronic decoupling of the iron phthalocyanine adsorbates from the substrate. The extent of the spin change and adsorbate substrate decoupling depends on which ligand is used. The X-ray photoelectron spectroscopy results suggest that a covalent bond is formed between the NO and CO adsorbates and the FePc iron ion, and that the NO and CO valence states hybridize with metal ion d states. The density functional theory calculations show that CO adsorbs in a linear configuration, while NO adsorption assumes a tilted geometry.
43.	Isvoranu, Cristina, et al. (author) Pyridine Adsorption on Single-Layer Iron Phthalocyanine on Au(111) 2011 In: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 115:41, s. 20201-20208 Journal article (peer-reviewed)abstract The adsorption of pyridine on monolayers of well-ordered, flat-lying iron phthalocyanine molecules on Au(111) is investigated by X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, and density functional theory. It is found that pyridine both coordinates to the iron site of iron phthalocyanine and binds weakly to other sites. The iron coordination causes significant changes in the electronic structure of the iron phthalocyanine compound, with the implication of a change of the spin properties of the iron atoms due to the strong ligand field created by the pyridine axial ligand. Both low coverages and multilayer coverages of pyridine are considered. At low doses, the pyridine molecules are ordered, whereas in multilayers, no preferred orientation is observed. The orientation of the FePc molecules with respect to the Au(111) surface is not affected by the adsorption of pyridine.
44.	Isvoranu, Cristina, et al. (author) Tuning the spin state of iron phthalocyanine by ligand adsorption 2010 In: Journal of Physics: Condensed Matter. - : IOP Publishing. - 1361-648X .- 0953-8984. ; 22:47 Journal article (peer-reviewed)abstract The future use of single-molecule magnets in applications will require the ability to control and manipulate the spin state and magnetization of the magnets by external means. There are different approaches to this control, one being the modification of the magnets by adsorption of small ligand molecules. In this paper we use iron phthalocyanine supported by an Au(111) surface as a model compound and demonstrate, using x-ray photoelectron spectroscopy and density functional theory, that the spin state of the molecule can be tuned to different values (S similar to 0, 1/2, 1) by adsorption of ammonia, pyridine, carbon monoxide or nitric oxide on the iron ion. The interaction also leads to electronic decoupling of the iron phthalocyanine from the Au(111) support.
45.	Jensen, Thomas N., et al. (author) Correlation between stoichiometry and surface structure of the polar MgAl2O4(100) surface as a function of annealing temperature 2015 In: Physical Chemistry Chemical Physics. - : Royal Society of Chemistry (RSC). - 1463-9084 .- 1463-9076. ; 17:8, s. 5795-5804 Journal article (peer-reviewed)abstract The correlation between surface structure, stoichiometry and atomic occupancy of the polar MgAl2O4(100) surface has been studied with an interplay of noncontact atomic force microscopy, X-ray photoelectron spectroscopy and surface X-ray diffraction under ultrahigh vacuum conditions. The Al/Mg ratio is found to significantly increase as the surface is sputtered and annealed in oxygen at intermediate temperatures ranging from 1073-1273 K. The Al excess is explained by the observed surface structure, where the formation of nanometer-sized pits and elongated patches with Al terminated step edges contribute to stabilizing the structure by compensating surface polarity. Surface X-ray diffraction reveals a reduced occupancy in the top two surface layers for both Mg, Al, and O and, moreover, vacancies are preferably located in octahedral sites, indicating that Al and Mg ions interchange sites. The excess of Al and high concentration of octahedral vacancies, very interestingly, indicates that the top few surface layers of the MgAl2O4(100) adopts a surface structure similar to that of a spinel-like transition Al2O3 film. However, after annealing at a high temperature of 1473 K, the Al/Mg ratio restores to its initial value, the occupancy of all elements increases, and the surface transforms into a well-defined structure with large flat terraces and straight step edges, indicating a restoration of the surface stoichiometry. It is proposed that the tetrahedral vacancies at these high temperatures are filled by Mg from the bulk, due to the increased mobility at high annealing temperatures.
46.	Johansson, Niclas, et al. (author) Ambient pressure phase transitions over Ir(1 1 1): at the onset of CO oxidation 2017 In: Journal of Physics: Condensed Matter. - 1361-648X. ; 29:44 Journal article (peer-reviewed)abstract In this study we report on the adsorbate structures on an Ir(1 1 1) surface during the phase transition from the inactive to the active state during CO oxidation. The CO oxidation over Pt(1 1 1) is used as a reference case. Where Pt(1 1 1) either is inactive and CO covered or active and O covered, Ir(1 1 1) exhibits a transition state with co-existing chemisorbed O and CO. The observed structural differences are explained in terms of DFT-calculated adsorption energies. For Pt(1 1 1) the repulsive CO–O interaction makes co-existing chemisorbed CO and O unfavourable, while for Ir(1 1 1) the stronger O and CO adsorption allows for overcoming the repulsive interaction. At the onset of CO oxidation over Ir(1 1 1), a CO structure containing defects forms, which enables O2 to dissociatively adsorb on the Ir(1 1 1) surface, thus enabling the CO oxidation reaction. At the mass transfer limit, the Ir(1 1 1) surface is covered by a chemisorbed O structure with defects; hence, the active surface is predominately chemisorbed O covered at a total pressure of 0.5 mbar and no oxide formation is observed.
47.	Johansson, Niclas, et al. (author) Oxidation of Ultrathin FeO(111) Grown on Pt(111) : Spectroscopic Evidence for Hydroxylation 2016 In: Topics in Catalysis. - : Springer Science and Business Media LLC. - 1022-5528 .- 1572-9028. ; 59:5-7, s. 506-515 Journal article (peer-reviewed)abstract Using high resolution and ambient pressure X-ray photoelectron spectroscopy we show that the catalytically active FeO $$-{2}$$ 2 trilayer films grown on Pt(111) are very active for water dissociation, in contrast to inert FeO(111) bilayer films. The FeO $$-{2}$$ 2 trilayer is so active for water dissociation that it becomes hydroxylated upon formation, regardless of the applied preparation method. FeO $$-{2}$$ 2 trilayers were grown by oxidation of FeO(111) bilayer films either with molecular oxygen in the mbar regime, or by NO $$-2$$ 2 and atomic oxygen exposures, respectively, in the ultrahigh vacuum regime. Because it was impossible to prepare clean FeO $$-{2}$$ 2 without any hydroxyls we propose that catalytically highly active FeO $$-{2}$$ 2 trilayer films are generally hydroxylated. In addition, we provide spectroscopic fingerprints both for Pt(111)-supported FeO(111) and FeO $$-2$$ 2 films that can serve as reference for future in situ studies.
48.	Johansson, Niclas, et al. (author) Sonogashira cross-coupling over Au(1 1 1): from UHV to ambient pressure 2017 In: Journal of Physics: Condensed Matter. - 1361-648X. ; 29:44 Journal article (peer-reviewed)abstract We have studied the reaction of phenylacetylene (PA) with chloro-, bromo-, and iodobenzene on the Au(1 1 1) surface as a model system for the gold-catalysed Sonogashira cross-coupling. Both ultrahigh vacuum-based and ambient pressure x-ray photoelectron spectroscopy show that iodo- and chlorobenzene (IB and CB) undergo the cross-coupling reaction towards diphenylacetylene. Bromobenzene (BB), in contrast, does not react in the UHV experiments. Further, at ambient pressure signs are found for poisoning of the Au(1 1 1) surface by a carbon species formed in the reaction. The understanding obtained in the reaction experiments are based on a thorough investigation of the adsorption of PA, IB, CB, and BB on the Au(1 1 1) surface by soft x-ray absorption spectroscopy and temperature-dependent x-ray photoelectron spectroscopy. In particular, the experiments provide the orientation of the intact adsorbates with respect to the surfaces at liquid nitrogen temperature. Dissociation in the temperature regime between −80 and −15 °C is observed for iodo- and chlorobenzene, but not for BB, in agreement with that only IB and CB, but not BB, react with PA to form diphenylacetylene. The difference is tentatively attributed to a difference in surface orientation of the different halobenzenes.
49.	Jonzén, Niclas, et al. (author) Rapid advance of spring arrival dates in long-distance migratory birds 2006 In: Science. - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 312:5782, s. 1959-1961 Journal article (peer-reviewed)abstract Several bird species have advanced the timing of their spring migration in response to recent climate change. European short-distance migrants, wintering in temperate areas, have been assumed to be more affected by change in the European climate than long-distance migrants wintering in the tropics. However, we show that tong-distance migrants have advanced their spring arrival in Scandinavia more than short-distance migrants. By analyzing a long-term data set from southern Italy, we show that long-distance migrants also pass through the Mediterranean region earlier. We argue that this may reflect a climate-driven evolutionary change in the timing of spring migration.
50.	Jørgensen, Jakob Holm, et al. (author) Symmetry-Driven Band Gap Engineering in Hydrogen Functionalized Graphene 2016 In: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 10:12, s. 10798-10807 Journal article (peer-reviewed)abstract Band gap engineering in hydrogen functionalized graphene is demonstrated by changing the symmetry of the functionalization structures. Small differences in hydrogen adsorbate binding energies on graphene on Ir(111) allow tailoring of highly periodic functionalization structures favoring one distinct region of the moiré supercell. Scanning tunneling microscopy and X-ray photoelectron spectroscopy measurements show that a highly periodic hydrogen functionalized graphene sheet can thus be prepared by controlling the sample temperature (Ts) during hydrogen functionalization. At deposition temperatures of Ts = 645 K and above, hydrogen adsorbs exclusively on the HCP regions of the graphene/Ir(111) moiré structure. This finding is rationalized in terms of a slight preference for hydrogen clusters in the HCP regions over the FCC regions, as found by density functional theory calculations. Angle-resolved photoemission spectroscopy measurements demonstrate that the preferential functionalization of just one region of the moiré supercell results in a band gap opening with very limited associated band broadening. Thus, hydrogenation at elevated sample temperatures provides a pathway to efficient band gap engineering in graphene via the selective functionalization of specific regions of the moiré structure.

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