Use of tin as a surfactant material for the growth of thin silver films on silicon oxide

In this letter, we report on the use of tin as an effective surfactant material for silver growing on silicon oxide. We observed that submonolayers of Sn pre-deposited on SiO₂ result in earlier film coalescence and formation of smoother Ag layers. We suggest that Sn atoms reduce the Ag-adatom mobility resulting in experimentally observed increased island density and decreased film roughness. Angle-resolved X-ray photoelectron spectroscopy reveals that Sn remains under the Ag layer giving circumstantial evidence that at later stages of Ag film growth Sn does not influence the interlayer transport.     

Synthetische Versuche in der Pyranthronreihe

Ohne Zusammenfassung     

UMTS radio network evaluation and optimization beyond snapshots

A new evaluation scheme for universal mobile telecommunications system (UMTS) radio networks is introduced. The approach takes the complex coupling of coverage and capacity through interference into account. Cell load estimates, otherwise obtained through Monte-Carlo simulation, can now be approximated without time-consuming iterative simulations on user snapshots. The two cornerstones are the generalization of interference coupling matrices from user snapshots to average load and the emulation of load control by an analytical scaling scheme. Building on the new evaluation scheme, two novel radio network optimization algorithms are presented: an efficient local search procedure and a mixed integer program that aims at designing the coupling matrix. Computational experiments for optimizing antenna tilts show that our new approaches outperform traditional snapshot models     

Exploring Cu/Al cluster growth and reactivity: from embryonic building blocks to intermetalloid,open-shell superatoms

Cluster growth reactions in the system [Cu₅](Mes)₅ + [Al₄](Cp*)₄ (Mes = mesitylene, Cp* = pentamethylcyclopentadiene) were explored and monitored by in situ LIFDI-MS and ¹H-NMR. Feedback into experimental design allowed for an informed choice and precise adjustment of reaction conditions and led to isolation of the intermetallic cluster [Cu₄Al₄](Cp*)₅(Mes) (1). Cluster 1 reacts with excess 3-hexyne to yield the triangular cluster [Cu₂Al](Cp*)₃ (2). The two embryonic [Cu₄Al₄](Cp*)₅(Mes) and [Cu₂Al](Cp*)₃ clusters 1 and 2, respectively, were shown to be intermediates in the formation of an inseparable composite of the closely related clusters [Cu₇Al₆](Cp*)₆ (3), [HCu₇Al₆](Cp*)₆ (3H) and [Cu₈Al₆](Cp*)₆ (4), which just differ by one Cu core atom. The radical nature of the open-shell superatomic [Cu₇Al₆](Cp*)₆ cluster 3 is reflected in its reactivity towards addition of one Cu core atom leading to the closed shell superatom [Cu₈Al₆](Cp*)₆ (4), and as well by its ability to undergo σ(C–H) and σ(Si–H) activation reactions of C₆H₅CH₃ (toluene) and (TMS)₃SiH (TMS = tris(trimethylsilyl)).

Cu/Al cluster growth reactions leading to open- and closed-shell superatoms are investigated. Therein, LIFDI-MS is presented as a powerful technique for the in situ detection of cluster identities and reactivity patterns.     

Non-isothermal crystallization kinetics and nucleation behavior of isotactic polypropylene composites with micro-talc

Journal of Thermal Analysis and Calorimetry - The current investigation has presented a new synthesis technique to prepare pentaethylene glycol-treated graphene nanoplatelets (PEG-GnP) and...