Synthesis and immobilization of molecular switches onto titaniumdioxide nanowires

The precursor [Fe^III(L)Cl (L = N,N′-bis(2′-hydroxy-3′-methyl-benzyliden)-1,7-diamino-4-azaheptane) is combined with [Mo(CN)₈]^4? yields a star shaped nona-nuclear cluster, [Mo^IV{(CN)Fe^III(L)}₈]Cl₄. This Fe₈Mo molecule is a high-spin system at room temperature. On cooling to 20 K some of the iron(III) centres in the molybdenum(IV)-star switch to the low-spin state as proven by Mössbauer spectroscopy. This molecule was deposited on TiO₂ nanowires by electrostatic interactions between the cluster cations and the surface functionalized titanium oxide nanowire. The synthesis and surface binding of the multistable molecular switch was demonstrated using IR and UV–Vis spectroscopy (high-resolution) transmission electron microscopy ((HR)TEM) and Mössbauer spectroscopy. High- and low-temperature Mössbauer spectra indicate that the spin state transition of the free cluster molecules is preserved after surface binding. The above results emphasize the possibility of fabricating molecule-based low-dimensional structures by using traditional bottom-up approaches based on the electrostatic interaction between the cluster cations and polymer functionalized nanowires. These results can be generalized for the application to both charged and non-charged molecules.     

Preprocessing of ion mobility spectra by lognormal detailing and wavelet transform

This study has developed an efficient preprocessing strategy for ion mobility spectrometry (IMS) data allowing for improved peak clarity and comparability of different measurements. Using the discrete wavelet transform for data compression and denoising, and fitting a lognormal function to the strong tailing of the reactant ion peak (RIP), enables a data reduction to 25% or less, a significant increase of the signal-to-noise ratio, and the successful elimination of the RIP tailing. The preprocessing of breath measurements obtained by coupling an IMS to a gaschromatographic column, has resulted in the desired outcome of smooth peaks lying on a common base level. These results are transferable to other applications of one- and two-dimensional separations with IMS or instrumentations generating a similar data structure.     

Frequency– and Time-domain BEM Analysis of Rigid Track on a Half-Space with Vibration Barriers

The rapid development of high-speed trains like the TGV or the ICE in recent years results in high dynamic loads causing vibrations which propagate from the train-track structure into the ground and further into nearby buildings. In this context it is important to develop rigid tracks with improved dynamic behaviour and to investigate possible means of vibration reduction. The boundary element method in frequency and time domain is used to simulate train-track structures subjected to dynamic loading and the reduction of vibrations which for instance can be achieved via a trench running parallel to the rigid track. In this context the non-causality error, which arises when the time-domain BEM algorithm is applied to mathematically concave domains, is discussed and the substructure method is proposed as a solution to this problem. A two-layered cylindrical elastic structure on a half-space with a trench is added as an example of a possible application.     

Variation of Neumann and Green functions under homotopies of the boundary

We develop variational formulas for certain Neumann and Green functions of multiply connected planar domains, valid for any smooth homotopy of the boundary. The modified Neumann and Green functions under consideration arise in the study of holomorphic functions with single-valued primitives.     

Synthesis of di- and tetraalkyl-3-piperazinoisoquinolines and related compounds as potential antidepressant agents

A series of di- and tetraalkyl-3-piperazinoisoquinolines and related compounds was synthesized via di- and tetraalkylated 1-indanones as intermediates.     

Enantiomeric 3,7-Dimethylocta-1,7-dienes as Useful Chiral Building Blocks. A New Access to Both Optical Antipodes of Natural (E)-3,7-Dimethyloct-2-ene-1,8-diol and (E)-3,7-Dimethyloct-2-ene-1,8-dicarboxylic Acid

Ozonolysis of the easily available monoterpenoids (?)- 1 and (+)- 1 leads in high yield to the ketoaldehydes (?)- 4 and (+)- 4 , which serve as convenient intermediates for efficient new routes to both optical antipodes of the naturally occurring octenediol (E)- 2 (Monarch butterfly secretion product) and octene-dicarboxylic acid (E)- 3 (Callosobruchus chinensis sex pheromone). All steps proceed with almost complete retention of configuration, ensuring the synthesis of the target compounds with high optical purity.     

Electrochemical stripping with carbon fiber electrodes in a microliter-capacity cell

The construction of a microcell with an in-situ mercury-plated carbon fiber electrode for the application of electrochemical stripping techniques is described. The performance of the cell is compared to a conventional mercury-film glassy carbon electrode in large-volume cells with special emphasis on the effects of mass transport and oxygen interference. Effective mass transport is provided withouth forced convection and oxygen does not appear to influence the response of the carbon fiber electrode. The dependence of the a.s.v. and p.s.a. signals on the deposition time with the microcell deviated from linearity at deposition times above 3 min because of depletion effects and decreased concentration of oxidizing agent, respectively. Good reproducibility of lead determinations in the μg 1^?1 range by a.s.v. and p.s.a. was achieved in successive scans at the same fiber and in consecutive tests of identical samples. Calibration plots were linear in the 0.01–10 mg 1^?1 range. Sample volumes down to 5 μl were used in determining cadmium and lead. The detection limits for both elements obtained with a.s.v. and p.s.a. after 5-min preconcentration were 1 and 3 μg1^?1, respectively, or in absolute mass 5 pg and 15 pg, respectively.