Observation of doubly charged lead clusters below the critical size limit for Coulomb explosion of sphere configurations

Doubly charged lead clusters Pb₇²⁺, Pb₉²⁺, Pb₁₁²⁺ and Pb₁₃²⁺, far below the critical size for Coulomb explosion of par ticles with sphere like configurations (Pb₃₀) have been detected in time of flight mass spectra. Their existence can be explained by chain-like clusters.     

Biorthogonalentwicklungen analytischer Funktionen nach Eigenlösungen linearer Differentialgleichungen

Ohne Zusammenfassung     

Structure elucidation of a new friedelane triterpene from the mangrove plant Hibiscus tiliaceus

From the stem and bark of the mangrove plant Hibiscus tiliaceus, a new friedelane-type triterpene named 27-oic-3-oxo-28-friedelanoic acid (1) together with eight known triterpenoids involving five friedelane-type derivatives was isolated. The structure of 1 was determined by extensive 2D NMR (DQF-COSY, HMQC, HMBC, and NOESY) data analyses. All the compounds were obtained from mangrove plants for the first time.     

Theoretical study of small silicon clusters on a graphite layer

In a series of recent experiments, the HOMO-LUMO energy gaps of small Si clusters deposited on a graphite substrate have been determined by Scanning Tunneling Microscopy (STM). The values obtained were found to be substantially smaller than the energy gaps of corresponding passivated clusters. This work considers dimensional reduction as a possible mechanism for a sizeable energy gap narrowing by the example of the system Si₅. The impact of the graphite substrate on the deposited species is investigated in the framework of a pseudocluster model. Received 30 November 2000     

Melemium Hydrogensulfate H3C6N7(NH2)3(HSO4)3 – the First Triple Protonation of Melem

We synthesized melemium hydrogensulfate H₃C₆N₇(NH₂)₃(HSO₄)₃ by reaction of melem with 70 % sulfuric acid. The crystal structure was elucidated by single‐crystal XRD (P2₁/n (no. 14), Z = 4, a = 10.277(2), b = 14.921(3), c = 11.771(2) Å, β = 99.24(3)°, V = 1781.5(6) Å³). H₃C₆N₇(NH₂)₃(HSO₄)₃ is the first compound displaying a triple protonation of melem., In this contribution an overview of accessible melemium sulfates depending on the concentration of sulfuric acid is given. Two additional melemium sulfates were identified this way.     

Identification of archaeal proteins that affect the exosome function in vitro

Background  

The archaeal exosome is formed by a hexameric RNase PH ring and three RNA binding subunits and has been shown to bind and degrade RNA in vitro. Despite extensive studies on the eukaryotic exosome and on the proteins interacting with this complex, little information is yet available on the identification and function of archaeal exosome regulatory factors.