Evaluation of automotive disk brake noise behavior using piezoceramic actuators and sensors

One problem of disk brakes is the occurence of noise. This work in particular addresses the occurrence of disk brake squeal with frequencies from 1 up to 12 kHz which does generally not affect the basic functionality of the brake. Nevertheless it is a serious comfort problem and it causes a high amount of costs to design noiseless brake systems. This work examines methods to evaluate the noise behaviour of disk brakes using piezoceramic actuators and sensors. In comparison to conventional methods they provide the advantage to quantify the effect of new design features without the necessity to make the brake squeal. In this paper the investigation of phase shifts between characteristic dynamic state variables is examined more in detail. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Vibrational spectra of clioquinol and its Cu(II) complex

The infrared and Raman spectra of 5‐chloro‐7‐iodo‐8‐hydroxyquinoline (clioquinol, CQ) and that of its Cu(II) complex of stoichiometry [Cu(CQ)₂] were recorded and briefly discussed. Some comparisons were made with related complexes. The interest of the investigated systems in relation to Alzheimer's disease is briefly commented. Copyright © 2006 John Wiley & Sons, Ltd.     

A Modified Linear Sampling Method Valid for all Frequencies and an Application to the Inverse Inhomogeneous Medium Problem

We consider the inverse inhomogeneous medium scattering problem in acoustics where one tries to recover the support of anomalies in a medium by interrogating the region of interest with plane waves at fixed frequency. We discuss the validity of the Linear Sampling Method (LSM) for solving this inverse problem, and its connection to an unusual eigenvalue problem. It turns out that the existence of non-trivial solutions of the so-called interior transmission eigenvalue problem results in the failure of the LSM. We then propose a modification of the LSM that avoids these shortcomings and is numerically sound. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Xylityl Sesquicaprylate Efficacy as an Antiseptic Ingredient for Oral Care Products (Mouthwash): An In Vitro Screening Investigation against Eight Microorganisms

For dental caries and periodontal diseases initiated by dental plaque (as bacterial communities) and to inhibit the growth of oral pathogenic bacteria, oral care products containing antiseptic active ingredients are highly recommended, nonetheless, side effects of such actives are a concern (teeth discoloration/staining and taste perception, for example). In this context, we challenged xylityl sesquicaprylate, an antiseptic compound from natural resources, as an active ingredient to be used in an alcohol-free mouthwash formulation. The xylityl sesquicaprylate sample was compared to a respective blank mouthwash formulation and one containing triclosan. The in vitro efficacy was screened by the time-kill assay against eight microorganisms. The xylityl sesquicaprylate-containing mouthwash (0.45% w/w) presented a particularly interesting profile of efficacy against Actinomyces viscosus, Fusobacterium nucleatum, Porphyromonas gingivalis, and Tannerella forsythia, with results of greater magnitude to reduce the log₁₀ of those microorganisms in comparison with the triclosan sample.     

Enantioselective addition of diethylzinc to aldehydes catalyzed by 5-cis-substituted proline derivatives

5-Cis-substituted prolinols, prolinamines, and prolinamine sulfonamides proved to be efficient ligands for the enantioselective addition of diethylzinc to aldehydes, providing up to 99% ee. The sense of asymmetric induction can be controlled by the nature of the exocyclic functional group (CPh₂OH vs. CH₂NHR vs. CH₂NHSO₃R). The additional 5-cis substituent exerts a strong beneficial effect on the chirality transfer since it rigidifies the catalyst structure. The stereochemical outcome of the reactions is discussed in detail on the respective transition states.