Coupling Electrochemistry with Probe Electrospray Ionization Mass Spectrometry

A new coupling of electrochemistry with mass spectrometry (MS) using probe electrospray ionization (PESI) is presented. Due to the high salt tolerance of PESI, the detection of electrochemical reaction products in room‐temperature ionic liquids (RTILs) is realized for the first time. Furthermore, PESI‐MS allows the analysis of electrochemical reaction products on different or multiple electrode surfaces. In addition, peptides and proteins fractionated through isoelectric focusing (IEF) in the presence of an external electric field can also be directly analyzed by using PESI‐MS, suggesting a new and rapid characterization means for the IEF technique. This study reveals the versatility of EC/PESI‐MS, which could have an impact in electrochemistry and bioanalysis fields.     

Psychoacoustics of in-car switch buttons: From feelings to engineering parameters

The car interior is becoming quieter and other sounds are now exposed to user perception, such as the sound produced by interface buttons when actuated. So, the functional role of the button sound on interface operation and its aesthetic and emotional role on the user experience are now more important than before. However, little research and design effort has been paid to understand how to design buttons that produce a pleasant sound. Moreover, the button’s sound requirements received by interface manufacturers are ill-defined, insufficient or even inexistent, and consequently their conversion into specifications for manufacturing is problematic and leads to long and costly development processes. The purpose of this paper is to contribute to identify relevant acoustic parameters that explain the users sound preferences. Data on preference subjective judgments were collected and buttons acoustic signals were measured allowing the development of preference models based on partial least squares regression and neural networks methods. The former was successful in selecting the relevant parameters to describe the preference ratings of the buttons sound. The later, dealing with the non-linear nature of acoustic perception, was able to predict preferences based on the relevant parameters.     

Flanking transmission of metal stud walls with different junction details

Measurements of the normalised flanking sound level difference of different gypsum board flanking walls are reported. Results of a “standard” wall construction confirmed some results of the current draft standard of DIN 4109. Different constructions with various junction details and different wall constructions are described and measurement results are presented. By additional measurements on the walls, a prediction model for the weighted flanking level difference is suggested, based on the methodology of EN 12354. For the flanking transmission prediction of path Ff, three transmission paths are proposed. The model gives good agreement between calculated and measured weighted flanking level difference except for the case where the transmission along the inner lining of the flanking wall is dominant. In this case the prediction underestimates measurements by up to 7 dB.     

Correspondence between two types of rating indices for the heavy weight floor impact sound insulation of residential buildings

Of the two types of rating indices for the heavy weight floor impact sound insulation, the method of utilizing a rubber ball impact source combined with A-weighted sound level and the method utilizing a tire impact source combined with L-rating curve, the advantage of the former has been reported. In order to extend the advantage, the possibility was studied of estimating the rating utilizing the rubber ball impact source, based on the measurement results utilizing the tire impact source, especially for the case of a double leaf wooden floor. The correlation between the indices is not high enough to estimate one of them directly from the other with an accuracy not incorrectly estimating the rating grade of 5 dB step. The use of predictor variables, such as the special specifications of the double leaf wooden floor, for example, the use of sound insulation sheet, and the floor impact sound levels in the 31.5-Hz, 63-Hz and 125-Hz bands, is possibly able to increase the accuracy. Three principal types of multiple regression equation were derived through the analysis of measurement results in existing residential buildings.     

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在分析软硬阈值去噪特点的基础上,提出一种改进的小波阈值函数。根据Langmuir探针I-V特性曲线的特点,提出一种改进的标准差估算方法来计算小波阈值。采用基于改进标准差和改进阈值函数的小波对探针特性曲线进行去噪,仿真结果表明,改进的方法取得了良好的去噪效果,提高了信号的信噪比,降低了均方误差,去噪效果优于传统阈值去噪方法。     

Laser‐pump/X‐ray‐probe experiments with electrons ejected from a Cu(111) target: space‐charge acceleration

A comprehensive investigation of the emission characteristics for electrons induced by X‐rays of a few hundred eV at grazing‐incidence angles on an atomically clean Cu(111) sample during laser excitation is presented. Electron energy spectra due to intense infrared laser irradiation are investigated at the BESSY II slicing facility. Furthermore, the influence of the corresponding high degree of target excitation (high peak current of photoemission) on the properties of Auger and photoelectrons liberated by a probe X‐ray beam is investigated in time‐resolved pump and probe measurements. Strong electron energy shifts have been found and assigned to space‐charge acceleration. The variation of the shift with laser power and electron energy is investigated and discussed on the basis of experimental as well as new theoretical results.     

Raman spectroscopic evidence for the inclusion of decanoate ion in trimethyl-β-cyclodextrin

A method for calibrating Raman intensities of diluted aqueous solutions, based on the integrated intensity of the OH stretching bands of liquid water as an external intensity standard, is described and used to obtain a difference spectrum that reveals intensity changes mainly due to the intermolecular interaction between two solutes. The method is applied to trimethyl-β-cyclodextrin in sodium decanoate aqueous solutions. The difference between the interaction spectra above and below the critical micellar concentration of sodium decanoate, in the CH stretching region between 2700 and 3100 cm⁻¹, shows an intensity increase of the CH stretching bands for trimethyl-β-cyclodextrin above the critical micellar concentration of sodium decanoate, whereas β-cyclodextrin is relatively insensitive to the presence of decanoate ion micelles in aqueous solution.     

Linear Schiff-base fluorescence probe with aggregation-induced emission characteristics for Al detection and its application in live cell imaging

A simple Schiff-base derivative with salicylaldehyde moieties as fluorescent probe 1 was reported by aggregation-induced emission (AIE) characterization for the detection of metal ions. Spectral analysis revealed that probe 1 was highly selective and sensitive to Al³⁺. The probe 1 was also subject to minimal interference from other common competitive metal ions. The detection limit of Al³⁺ was 0.4 μM, which is considerably lower than the World Health Organization standard (7.41 μM), and the acceptable level of Al³⁺ (1.85 μM) in drinking water. The Job's plot and the results of ¹H-NMR and FT-IR analyses indicated that the binding stoichiometry ratio of probe 1 to Al³⁺ was 1:2. Probe 1 demonstrated a fluorescence-enhanced response upon binding with Al³⁺ based on AIE characterization. This response was due to the restricted molecular rotation and increased rigidity of the molecular assembly. Probe 1 exhibited good biocompatibility, and Al³⁺ was detected in live cells. Therefore, probe 1 is a promising fluorescence probe for Al³⁺ detection in the environment.     

Volumetric Properties of Tetra-n-butyl ammonium bromide in Aqueous Solutions of Magnesium sulphate in the Temperature Range 298.15 to 318.15K and under the Atmospheric Pressure

Density and sound speed measurements have been carried out for the ternary systems consisting of tetra-n-butyl ammonium bromide (TBAB) in 0.1 m aqueous magnesium sulphate heptahydrate (MgSO₄.7H₂O)-water over the full range of composition from T = 293.15 to 318.15 K by using volumetric method. Using this experimental data, various physical and thermodynamical parameters such as adiabatic compressibility, apparent molal compressibility, apparent molal volume, apparent and limiting partial molar volumes of the electrolytes and ions in these mixtures have been evaluated and split into respective ionic contributions. The results have been discussed in terms of ion–ion and ion–solvent interactions occurring between TBAB and aqueous MgSO₄ solutions. Further, structure making/breaking behaviour of MgSO4 has been reported in terms of sign of the partial molar expansibility at infinite dilution.     

On the decay rates of Timoshenko system with second sound

In this work, we study the well‐posedness and the asymptotic stability of a one‐dimensional linear thermoelastic Timoshenko system, where the heat conduction is given by Cattaneo's law and the coupling is via the displacement equation. We prove that the system is exponentially stable provided that the stability number χ_τ=0. Otherwise, we show that the system lacks exponential stability. Furthermore, in the latter case, we show that the solution decays polynomially. Copyright © 2015 John Wiley & Sons, Ltd.