Analysis of Gas-Phase Clusters Made from Laser-Vaporized Icosahedral Al−Pd−Mn
An icosahedral Al-Pd-Mn quasicrystal sample is laser vaporized to form metal clusters by gas aggregation. The clusters are subsequently laser ionized and mass analyzed in a time-of-flight mass spectrometer. The mass spectra show cluster compositions which are qualitatively similar to that of the sample. This is consistent with a kinetically controlled cluster growth process. Cluster thermodynamic stability is probed by multiphoton ionization/fragmentation, which induces primarily Al and Mn loss. The resulting spectra are composed of a series of Pd-rich Al-Pd clusters. The average cluster composition is 60 (′1)% Pd. This composition is close to a known eutectic in the Al-Pd system. When manganese is seen on these clusters, it is always in units of Mn 3 . These results are discussed in terms of relative binding strengths in the Al-Pd-Mn alloy system.
The Dopant Aluminum Enhances CO Oxidation Catalyzed by Subnanometer Small Palladium Clusters: A DFT Study
We have elucidated the mechanism of CO oxidation catalyzed by AlPdn (n = 1–3) clusters through first-principle density-functional theory (DFT) calculation. It is found that these subnanometer species transfer into reaction complexes which catalyzes CO oxidation through two different mechanisms, occurring via Langmuir-Hinshelwood paths. It is shown that mixing two different metals (Al and Pd) can have more beneficial effects than pure palladium on the catalytic activity and the alloyed AlPd2 cluster is proposed as the best effective nanocatalysts.
Antitumor activities of (2"R)-4'-O-tetrahydropyranyl-adriamycin (THP) and its combination with other antitumor agents on murine tumors.
(2''R)-4'-O-Tetrahydropyranyladriamycin (THP) is a new derivative of doxorubicin (adriamycin, ADM). The concentrations of THP and ADM required to inhibit by 50% the growth of a cultured L1210 cells was 0.003 microgram/ml and 0.016 microgram/ml, respectively. Various therapeutic designs of combinations of THP with other antitumor agents were investigated in vivo using the L1210 murine leukemia. The combination of THP with cytosine arabinoside (Ara-C), cyclocytidine hydrochloride (Cyclo-C), 6-mercaptopurine (6-MP) and cyclophosphamide (EX) showed a great effectiveness following daily intraperitoneal treatment from days 1 to 10. High therapeutic effects were also obtained with the combinations of THP with Ara-C, Cyclo-C, vincristine (VCR) and EX following intravenous combination therapy one day following implantation of L1210 leukemia. Schedule dependency and its therapeutic efficacy of THP were examined. THP showed almost the same antitumor activity on the solid-type sarcoma-180 or solid-type Ehrlich carcinoma as ADM by intraperitoneal or intravenous treatment. THP showed some superior activity to ADM in the advanced stage of L1210 leukemia. High antitumor activity of THP on murine leukemia L1210 has been reported by Tsuruo et al. (Cancer Res. 42: 1462-1467, 1982) and was also confirmed. THP gave many mice cures, especially in the intravenous treatment.