| 1. |
- LaRue, Jerry, et al.
(författare)
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Real-Time Elucidation of Catalytic Pathways in CO Hydrogenation on Ru
- 2017
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Ingår i: The Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 8:16, s. 3820-3825
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Tidskriftsartikel (refereegranskat)abstract
- The direct elucidation of the reaction pathways in heterogeneous catalysis has been challenging due to the short-lived nature of reaction intermediates. Here, we directly measured on ultrafast time scales the initial hydrogenation steps of adsorbed CO on a Ru catalyst surface, which is known as the bottleneck reaction in syngas and CO2 reforming processes. We initiated the hydrogenation of CO with an ultrafast laser temperature jump and probed transient changes in the electronic structure using real-time X-ray spectroscopy. In combination with theoretical simulations, we verified the formation of CHO during CO hydrogenation.
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| 2. |
- Lykke, J. M., et al.
(författare)
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The ALMA-PILS survey: First detections of ethylene oxide, acetone and propanal toward the low-mass protostar IRAS 16293-2422
- 2017
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 597, s. A53-
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Tidskriftsartikel (refereegranskat)abstract
- Context. One of the open questions in astrochemistry is how complex organic and prebiotic molecules are formed. The unsurpassed sensitivity of the Atacama Large Millimeter/submillimeter Array (ALMA) takes the quest for discovering molecules in the warm and dense gas surrounding young stars to the next level. Aims. Our aim is to start the process of compiling an inventory of oxygen-bearing complex organic molecules toward the solar-type Class 0 protostellar binary IRAS 16293-2422 from an unbiased spectral survey with ALMA, Protostellar Interferometric Line Survey (PILS). Here we focus on the new detections of ethylene oxide (c-C2H4O), acetone (CH3COCH3), and propanal (C2H5CHO). Methods. With ALMA, we surveyed the spectral range from 329 to 363 GHz at 0.5? (60 AU diameter) resolution. Using a simple model for the molecular emission in local thermodynamical equilibrium, the excitation temperatures and column densities of each species were constrained. Results. We successfully detect propanal (44 lines), ethylene oxide (20 lines) and acetone (186 lines) toward one component of the protostellar binary, IRAS 16293B. The high resolution maps demonstrate that the emission for all investigated species originates from the compact central region close to the protostar. This, along with a derived common excitation temperature of Tex ? 125 K, is consistent with a coexistence of these molecules in the same gas. Conclusions. The observations mark the first detections of acetone, propanal and ethylene oxide toward a low-mass protostar. The relative abundance ratios of the two sets of isomers, a CH3COCH3/C2H5CHO ratio of 8 and a CH3CHO/c-C2H4O ratio of 12, are comparable to previous observations toward high-mass protostars. The majority of observed abundance ratios from these results as well as those measured toward high-mass protostars are up to an order of magnitude above the predictions from chemical models. This may reflect either missing reactions or uncertain rates in the chemical networks. The physical conditions, such as temperatures or densities, used in the models, may not be applicable to solar-type protostars either.
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| 3. |
- Miller, D. J., et al.
(författare)
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Oxidation of Pt(111) under Near-Ambient Conditions
- 2011
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 107:19, s. 195502-
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Tidskriftsartikel (refereegranskat)abstract
- The oxidation of Pt(111) at near-ambient O(2) pressures has been followed in situ using x-ray photoelectron spectroscopy (XPS) and ex situ using x-ray absorption spectroscopy (XAS). Polarization-dependent XAS signatures at the O K edge reveal significant temperature-and pressure-dependent changes of the Pt-O interaction. Oxide growth commences via a PtO-like surface oxide that coexists with chemisorbed oxygen, while an ultrathin alpha-PtO(2) trilayer is identified as the precursor to bulk oxidation. These results have important implications for understanding the chemical state of Pt in catalysis.
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| 4. |
- Strosberg, J., et al.
(författare)
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Phase 3 Trial of Lu-177-Dotatate for Midgut Neuroendocrine Tumors
- 2017
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Ingår i: New England Journal of Medicine. - 0028-4793 .- 1533-4406. ; 376:2, s. 125-135
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND Patients with advanced midgut neuroendocrine tumors who have had disease progression during first-line somatostatin analogue therapy have limited therapeutic options. This randomized, controlled trial evaluated the efficacy and safety of lutetium-177 (Lu-177)-Dotatate in patients with advanced, progressive, somatostatin-receptor-positive midgut neuroendocrine tumors. METHODS We randomly assigned 229 patients who had well-differentiated, metastatic midgut neuroendocrine tumors to receive either Lu-177-Dotatate (116 patients) at a dose of 7.4 GBq every 8 weeks (four intravenous infusions, plus best supportive care including octreotide long-acting repeatable [LAR] administered intramuscularly at a dose of 30 mg) (Lu-177-Dotatate group) or octreotide LAR alone (113 patients) administered intramuscularly at a dose of 60 mg every 4 weeks (control group). The primary end point was progression-free survival. Secondary end points included the objective response rate, overall survival, safety, and the side-effect profile. The final analysis of overall survival will be conducted in the future as specified in the protocol; a prespecified interim analysis of overall survival was conducted and is reported here. RESULTS At the data-cutoff date for the primary analysis, the estimated rate of progression-free survival at month 20 was 65.2% (95% confidence interval [CI], 50.0 to 76.8) in the Lu-177-Dotatate group and 10.8% (95% CI, 3.5 to 23.0) in the control group. The response rate was 18% in the Lu-177-Dotatate group versus 3% in the control group (P<0.001). In the planned interim analysis of overall survival, 14 deaths occurred in the Lu-177-Dotatate group and 26 in the control group (P = 0.004). Grade 3 or 4 neutropenia, thrombocytopenia, and lymphopenia occurred in 1%, 2%, and 9%, respectively, of patients in the Lu-177-Dotatate group as compared with no patients in the control group, with no evidence of renal toxic effects during the observed time frame. CONCLUSIONS Treatment with Lu-177-Dotatate resulted in markedly longer progression-free survival and a significantly higher response rate than high-dose octreotide LAR among patients with advanced midgut neuroendocrine tumors. Preliminary evidence of an overall survival benefit was seen in an interim analysis; confirmation will be required in the planned final analysis. Clinically significant myelosuppression occurred in less than 10% of patients in the Lu-177-Dotatate group. (Funded by Advanced Accelerator Applications; NETTER-1 ClinicalTrials. gov number, NCT01578239; EudraCT number 2011-005049-11.)
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| 5. |
- Coutens, A., et al.
(författare)
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The ALMA-PILS survey: First detections of deuterated formamide and deuterated isocyanic acid in the interstellar medium
- 2016
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 590
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Tidskriftsartikel (refereegranskat)abstract
- Formamide (NH2CHO) has previously been detected in several star-forming regions and is thought to be a precursor for different prebiotic molecules. Its formation mechanism is still debated, however. Observations of formamide, related species, and their isopotologues may provide useful clues to the chemical pathways leading to their formation. The Protostellar Interferometric Line Survey (PILS) represents an unbiased, high angular resolution and sensitivity spectral survey of the low-mass protostellar binary IRAS 16293-2422 with the Atacama Large Millimeter/submillimeter Array (ALMA). For the first time, we detect the three singly deuterated forms of NH2CHO (NH2CDO, cis-and trans-NHDCHO), as well as DNCO towards the component B of this binary source. The images reveal that the different isotopologues are all present in the same region. Based on observations of the 13C isotopologues of formamide and a standard 12C/13C ratio, the deuterium fractionation is found to be similar for the three different forms with a value of about 2%. The DNCO/HNCO ratio is also comparable to the D/H ratio of formamide (~1%). These results are in agreement with the hypothesis that NH2CHO and HNCO are chemically related through grain-surface formation.
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| 6. |
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| 7. |
- Fjällskog, Marie-Louise H., et al.
(författare)
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Treatment with Combined Streptozotocin and Liposomal Doxorubicin in Metastatic Endocrine Pancreatic Tumors
- 2008
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Ingår i: Neuroendocrinology. - : S. Karger AG. - 0028-3835 .- 1423-0194. ; 88:1, s. 53-8
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Tidskriftsartikel (refereegranskat)abstract
- Treatment with combined streptozotocin and liposomal doxorubicin is safe and efficient in patients with endocrine pancreatic tumors (EPTs). No cardiac toxicity was reported. BACKGROUND: The combination of streptozotocin and doxorubicin has been shown to be superior to streptozotocin and fluorouracil in the treatment of metastatic EPTs. However, the risk of cardiac toxicity from anthracyclins hampers the usefulness of the drug combination. Liposomal doxorubicin has a lower frequency of cardiac adverse events compared to doxorubicin. We wanted to assess the efficacy and safety of combined streptozotocin and liposomal doxorubicin in patients with metastatic EPTs. METHODS: Thirty patients with metastatic EPTs were recruited from three medical centers in Norway and Sweden during a time period of 3 years. All patients had histopathologically confirmed diagnoses and bidimensionally measurable lesions. 30 mg/m(2) of liposomal doxorubicin was administered on day 1 of each cycle. During the first course, 1 g of streptozotocin was given on 5 consecutive days. Thereafter, 2 g of streptozotocin was given on day 1 only. Treatment was repeated every 3 weeks. RESULTS: Twelve of 30 patients (40%) achieved an objective radiological response with a median duration of 9 months. Stabilization of disease was achieved in 17 of 30 patients (57%) for a median duration of 11 months. Only one patient had progressive disease as best response. The 2-year progression-free survival was 18% and the 2-year overall survival was 72%. The treatment was well tolerated. None of the patients experienced cardiac toxicity. CONCLUSION: We conclude that combined streptozotocin and liposomal doxorubicin is a safe and efficient treatment for EPTs. The efficacy seems to be comparable to that of combined streptozotocin and doxorubicin, whereas the cardiac toxicity clearly favors using the liposomal drug combination. 2008 S. Karger AG, Basel.
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| 8. |
- Iwata, H.P., et al.
(författare)
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Effective masses of two-dimensional electron gases around cubic inclusions in hexagonal silicon carbide
- 2003
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X .- 0163-1829. ; 68:24, s. 245309-1
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Tidskriftsartikel (refereegranskat)abstract
- The main purpose of this article is to determine the two-dimensional effective mass tensors of electrons confined in thin 3C wells in hexagonal SiC, which is a first step in the understanding of in-plane electron motion in the novel quantum structures. We have performed ab initio band structure calculations, based on the density functional theory in the local density approximation, for single and multiple stacking faults leading to thin 3C-like regions in 4H- and 6H-SiC and deduced electron effective masses for two-dimensional electron gases around the cubic inclusions. We have found that electrons confined in the thin 3C-like layers have clearly heavier effective masses than in the perfect bulk 3C-SiC single crystal.
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| 9. |
- Klimstra, David S., et al.
(författare)
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Pathology reporting of neuroendocrine tumors : application of the Delphic consensus process to the development of a minimum pathology data set
- 2010
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Ingår i: American Journal of Surgical Pathology. - 0147-5185 .- 1532-0979. ; 34:3, s. 300-313
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Tidskriftsartikel (refereegranskat)abstract
- Epithelial neuroendocrine tumors (NETs) have been the subject of much debate regarding their optimal classification. Although multiple systems of nomenclature, grading, and staging have been proposed, none has achieved universal acceptance. To help define the underlying common features of these classification systems and to identify the minimal pathology data that should be reported to ensure consistent clinical management and reproducibility of data from therapeutic trials, a multidisciplinary team of physicians interested in NETs was assembled. At a group meeting, the participants discussed a series of "yes" or "no" questions related to the pathology of NETs and the minimal data to be included in the reports. After discussion, anonymous votes were taken, using the Delphic principle that 80% agreement on a vote of either yes or no would define a consensus. Questions that failed to achieve a consensus were rephrased once or twice and discussed, and additional votes were taken. Of 108 questions, 91 were answerable either yes or no by more than 80% of the participants. There was agreement about the importance of proliferation rate for tumor grading, the landmarks to use for staging, the prognostic factors assessable by routine histology that should be reported, the potential for tumors to progress biologically with metastasis, and the current status of advanced immunohistochemical and molecular testing for treatment-related biomarkers. The lack of utility of a variety of immunohistochemical stains and pathologic findings was also agreed upon. A consensus could not be reached for the remaining 17 questions, which included both minor points related to extent of disease assessment and some major areas such as terminology, routine immunohistochemical staining for general neuroendocrine markers, use of Ki67 staining to assess proliferation, and the relationship of tumor grade to degree of differentiation. On the basis of the results of the Delphic voting, a minimum pathology data set was developed. Although there remains disagreement among experts about the specific classification system that should be used, there is agreement about the fundamental pathology data that should be reported. Examination of the areas of disagreement reveals significant opportunities for collaborative study to resolve unanswered questions.
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| 10. |
- Lauridsen, Jonas, et al.
(författare)
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Microstructure evolution of Ti-Si-C-Ag nanocomposite coatings deposited by DC magnetron sputtering
- 2010
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Ingår i: Acta Materialia. - : Elsevier Ltd.. - 1359-6454 .- 1873-2453. ; 58:20, s. 6592-6599
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Tidskriftsartikel (refereegranskat)abstract
- Nanocomposite coatings consisting of Ag and TiCx (x < 1) crystallites in a matrix of amorphous SiC were deposited by high-rate magnetron sputtering from Ti-Si-C-Ag compound targets. Different target compositions were used to achieve coatings with a Si content of similar to 13 at.%, while varying the C/Ti ratio and Ag content. Electron microscopy, helium ion microscopy, X-ray photoelectron spectroscopy and X-ray diffraction were employed to trace Ag segregation during deposition and possible decomposition of amorphous SiC. Eutectic interaction between Ag and Si is observed, and the Ag forms threading grains which coarsen with increased coating thickness. The coatings can be tailored for conductivity horizontally or vertically by controlling the shape and distribution of the Ag precipitates. Coatings were fabricated with hardness in the range 10-18 GPa and resistivity in the range 77-142 mu Omega cm.
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