Interactions of Au cluster anions with oxygen

Experimental and theoretical evidence is presented for the nondissociative chemisorption of O2on free Au cluster anions (Au−n, n=number of atoms) with n=2, 4, 6 at room temperature, indicating that the stabilization of the activated di-oxygen species is the key for the unusual catalytic activities of Au-based catalysts. In contrast to Au−n with n=2, 4, 6, O2 adsorbs atomically on Aumonomer anions. For the Aumonomer neutral, calculations based on density functional theory reveal that oxygen should be molecularly bound. On Au dimer and tetramer neutrals, oxygen is molecularly bound with the O–O bond being less activated with respect to their anionic counterparts, suggesting that the excess electron in the anionic state plays a crucial role for the O–O activation. We demonstrate that interplay between experiments on gas phase clusters and theoretical approach can be a promising strategy to unveil mechanisms of elementary steps in nanocatalysis

Growth of Carbon Nanotubes on Carbon Fiber by Thermal CVD Using Ni Nanoparticles as Catalysts

AbstractNickel nanoparticles and thin film on carbon fiber have been prepared through electroless deposition. Moreover, carbon nanotubes were grown on carbon fiber covered by nickel nanoparticles using thermal chemical vapor deposition. The effects of changes in the thickness of the nickel catalyst layer and the growth temperature of carbon nanotubes were studied systemically, and the results are discussed in the present work

Growth kinetics, structure, and morphology of para-quaterphenyl thin films on gold(111)

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Clinical Outcomes and Prognostic Factors of Up-Front Autologous Stem Cell Transplantation in Patients with Extranodal Natural Killer/T Cell Lymphoma

AbstractLimited data exist on up-front autologous stem cell transplantation (ASCT) in extranodal natural killer/T cell lymphoma (ENKTL). Sixty-two patients (43 men and 19 women) with newly diagnosed ENKTL who underwent up-front ASCT after primary therapy were identified. Poor-risk characteristics included advanced stage (50%), high-intermediate to high-risk International Prognostic Index (25.8%), and group 3 to 4 of NK/T Cell Lymphoma Prognostic Index (NKPI, 67.7%). Pretransplant responses included complete remission in 61.3% and partial remission in 38.7% of patients, and final post-transplantation response included complete remission in 78.3%. Early progression occurred in 12.9%. At a median follow-up of 43.3 months (range, 3.7 to 114.6), 3-year progression-free survival (PFS) was 52.4% and 3-year overall survival (OS) was 60.0%. Patients with limited disease had significantly better 3-year PFS (64.5% versus 40.1%, P = .017) and OS (67.6% versus 52.3%, P = .048) than those with advanced disease. Multivariate analysis showed NKPI and pretransplant response were independent prognostic factors influencing survival, particularly NKPI in limited disease and pretransplant response in advanced disease. Radiotherapy was an independent factor for reduced progression and survival in patients with limited disease, but anthracycline-based chemotherapy was a poor prognostic factor for progression in patients with advanced disease. Up-front ASCT is an active treatment in ENKTL patients responding to primary therapy

Comparison of first-line treatment with CHOP versus ICED in patients with peripheral T-cell lymphoma eligible for upfront autologous stem cell transplantation

IntroductionUpfront autologous stem cell transplantation (ASCT) has been recommended for patients who are newly diagnosed with peripheral T-cell lymphoma (PTCL), and CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone), an anthracycline-based chemotherapy has been the frontline chemotherapy for PTCL. However, it is not clear whether anthracycline-based chemotherapies such as CHOP could be standard induction therapy for PTCL.MethodsWe conducted a randomized phase II study to compare CHOP with fractionated ifosfamide, carboplatin, etoposide, and dexamethasone (ICED) for patients eligible for ASCT. The primary endpoint was progression-free survival (PFS) and secondary endpoints included objective response rate, overall survival (OS), and safety profiles.ResultsPatients were randomized into either CHOP (n = 69) or ICED (n = 66), and the characteristics of both arms were not different. PTCL-not otherwise specified (NOS, n = 60) and angioimmunoblastic T-cell lymphoma (AITL, n = 53) were dominant. The objective response rate was not different between CHOP (59.4%) and ICED (56.1%), and the 3-year PFS was not different between CHOP (36.7%) and ICED (33.1%). In AITL patients, CHOP was favored over ICED whereas ICED was associated with more cytopenia and reduced dose intensity. Patients who received upfront ASCT after achieving complete response to CHOP or ICED showed 80% of 3-year OS.DiscussionIn summary, our study showed no therapeutic difference between CHOP and ICED in terms of response and PFS. Thus, CHOP might remain the reference regimen especially for AITL based on its better outcome in AITL, and upfront ASCT could be recommended as a consolidation of complete response in patients with PTCL

YM155 Induces EGFR Suppression in Pancreatic Cancer Cells

YM155, which inhibits the anti-apoptotic protein survivin, is known to exert anti-tumor effects in various cancers, including prostate and lung cancer. However, there are few reports describing the inhibitory effect of YM155 on human pancreatic cancers that highly express survivin. Here, we tested the effects of YM155 on a variety of cancer cell lines, including pancreatic cancer cells. We found that YM155 exerts an anti-proliferative effect in pancreatic cancer cells, inducing cell death through suppression of XIAP (X-linked inhibitor of apoptosis) as well as survivin without affecting the anti-apoptotic proteins Bcl-xL or Mcl-1. YM155 also inhibited tumor growth in vivo, reducing the size of pancreatic cancer cell line MIAPaCa-2 xenografts by 77.1% on day 31. Western blot analyses further showed that YM155 downregulated phosphoinoside 3-kinase (PI3K) expression and reduced the levels of phosphorylated (activated) extracellular signal-regulated kinase (ERK) and STAT3 (signal transducer and activator of transcription 3) in PANC-1 cells. Interestingly, we also found that YM155 downregulated the epidermal growth factor receptor (EGFR) in various cancer cell lines and induced the EGFR phosphorylation and ubiquitination of EGFR in PANC-1 cells. YM155 also modestly promoted the ubiquitination of survivin and XIAP. Therefore, YM155 acts through modulation of EGFR and survivin expression to subsequently reduce survival. We suggest that YM155 has potential as a therapeutic agent in the treatment of pancreatic cancer

Atomic-scale structure and catalytic reactivity of RuO2

The structure and reactivity of the oxygen phases on Ru(0001) and Ru(100) and the bulk RuO2(101) surface were studied by quantitative LEED I/E analysis, TDS and AES. On Ru(0001), the (2´ 2)-3O phase forms at an O coverage of 0.75 ML. The atomic structure of this phase turned out to be a (2´ 2) vacancy structure of a (1´ 1)-O network on Ru(0001). CO does not adsorb on the (2´ 2)-3O overlayer in sample temperature range of 100 K and 300 K. At O coverages above 2–3 ML, RuO2 grows on Ru single crystals. Under UHV conditions, RuO2(110) is formed on Ru(0001), while on Ru(100), the (100) face of RuO2 is exposed. CO molecules bind selectively and strongly on cus (coordinatively unsaturated sites) Ru atoms of these RuO2/Ru surfaces. The CO molecules on the RuO2(110) and RuO2(100) surfaces can readily recombine with the lattice O atoms to produce CO2. The oxide formation is responsible for the high activity of the O-rich phases of Ru(0001) for the CO oxidation. In addition, the weakly bound O species on the RuO2(110) surface was characterized, which may provide a more efficient reaction pathway of the CO oxidation at 350 K, and stabilize the RuO2 catalyst in that the CO-induced vacancies are healed. The bulk RuO2(101) crystal reveals an equally high activity for the CO oxidation reactions as the RuO2(110) and RuO2(100) surfaces

Atomare Struktur und katalytische Reaktivitaet von RuO2

Titel Contents Abstract 1 Zusammenfassung 2 Chapter 1 Introduction 3 Chapter 2 Experiment 7 Chapter 3 Structure of the Ru(0001)-(2×2)-3O phase 15 Chapter 4 CO oxidation over O-rich phases on Ru(0001) 30 Chapter 5 CO oxidation over O-rich phases on Ru(100) 81 Chapter 6 CO oxidation on RuO2(101) 100 Chapter 7 Conclusion 107 Reference 110 Acronyms 116 Acknowledgement 117 Curriculum vitae 118The structure and reactivity of the oxygen phases on Ru(0001) and Ru(100) and the bulk RuO2(101) surface were studied by quantitative LEED I/E analysis, TDS and AES. On Ru(0001), the (2´ 2)-3O phase forms at an O coverage of 0.75 ML. The atomic structure of this phase turned out to be a (2´ 2) vacancy structure of a (1´ 1)-O network on Ru(0001). CO does not adsorb on the (2´ 2)-3O overlayer in sample temperature range of 100 K and 300 K. At O coverages above 2 3 ML, RuO2 grows on Ru single crystals. Under UHV conditions, RuO2(110) is formed on Ru(0001), while on Ru(100), the (100) face of RuO2 is exposed. CO molecules bind selectively and strongly on cus (coordinatively unsaturated sites) Ru atoms of these RuO2/Ru surfaces. The CO molecules on the RuO2(110) and RuO2(100) surfaces can readily recombine with the lattice O atoms to produce CO2. The oxide formation is responsible for the high activity of the O-rich phases of Ru(0001) for the CO oxidation. In addition, the weakly bound O species on the RuO2(110) surface was characterized, which may provide a more efficient reaction pathway of the CO oxidation at 350 K, and stabilize the RuO2 catalyst in that the CO-induced vacancies are healed. The bulk RuO2(101) crystal reveals an equally high activity for the CO oxidation reactions as the RuO2(110) and RuO2(100) surfaces.Die Untersuchungen zur Struktur und Reaktivität von Sauerstoffphasen auf Ru(0001)- und Ru(100)-Oberflächen, und zu dem RuO2(101)-Volumenkristall wurden mittels quantitativer LEED I/E Analyse, TDS und AES durchgeführt. Auf Ru(0001) wird die (2´ 2)-3O-Phase bei einer O-Bedeckung von 0.75 ML gebildet. Die atomare Struktur der (2´ 2)-3O-Phase kann als (2´ 2)-Lochstruktur von der schon bekannten (1´ 1)-O beschrieben werden. Die CO-Moleküle adsorbieren nicht in die (2´ 2)-3O-Phase. Wenn die O-Bedeckung höher ist als 2 3 ML, entsteht RuO2 auf den Ru-Einkristalloberflächen. Unter UHV-Bedingung wachsen RuO2(110)-Domänen auf Ru(0001), während auf Ru(100) die (100)-Fläche von RuO2 parallel zur Substratoberfläche orientiert ist. CO-Moleküle können auf den cus (coordinatively unsaturated sites)-Ru-Atomen von RuO2-Strukturen mit hohen Bindungsenergien adsorbieren. Die CO-Moleküle auf diesen RuO2-Oberflächen können mit den Gitter-O-Atomen zu CO2 reagieren. Die Oxidbildung ist verantwortlich für die hohe Reaktivität der sauerstoffreichen Phasen. Ausserdem wurden die schwach gebundenen Sauerstoffatome auf der RuO2(110)-Oberfläche charakterisiert, die einen effektiveren Reaktionsweg für die CO-Oxidation bei 350 K anbieten. Die schwach gebundenen Sauerstoffatome können auch die RuO2-Katalysatoren dadurch stabilizieren, dass sie die von der CO-Oxidation entstehenden Fehlstellen der RuO2-Katalysatoren heilen. Der RuO2(101)-Volumenkristall zeigt eine ähnlich hohe Reaktivität bei der CO- Oxidation wie die RuO2(110)- und die RuO2(100)-Fläche

Formation of di-oxygen species on Ag anion clusters

Experiments using vibrationally resolved ultraviolet photoelectron spectroscopy show that oxygen selectively adsorbs on even-numbered Ag anion clusters, whereas the odd-numbered clusters are not chemically active. We provide evidence that O2 molecularly adsorbs on Ag anion clusters consisting of less than 15 atoms. O2 adsorption pattern for Ag anion clusters is quite analogous to that of Au anion clusters. We suggest that for the reactions efficiently catalyzed by Au-nanocatalysts, Ag nanoclusters can be a promising candidate as a building block of catalysts

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Experiments using vibrationally resolved ultraviolet photoelectron spectroscopy (UPS) provide evidence that dissociative chemisorption of N2 becomes less stable than the molecular chemisorption on small clusters consisting of less than 10 metal atoms, which can efficiently dissociate diatomic molecules in the bulk form. This result is different from the generally accepted view that undercoordinated atoms are chemically more reactive. Our observation can be rationalized with a less efficient screening of the positive holes in smaller clusters created by a metal to adsorbate charge transfer, caused by the lower number of the directly neighbouring atoms