A highly sensitive method to determine the washing resistance of artificial hair colours

Citation: IFSCC Magazine, 11 (2008) (2) 139–142 Abstract: Due to the improved performance of modern hair colorants, the high natural variability in hair qualities and the individual influences of manual product applications, colour care effects of cosmetic treatments are very difficult to detect. A new, highly sensitive test method to study the colour fading behaviour of human hair was established for a large variety of cosmetic treatments. This method is based on an automatic multistage application of standard wool tissues combined with automatic colour evaluation by means of CIE L × a × b × measurements (DIN 5033). The delta E values are the main interest because they include all information regarding the L (black vs. white), a (red‐green) and b (blue‐yellow) axes defined in the Hunter Lab colour space. For validation of this new method, different permanent and non‐permanent hair colour shades were applied to undamaged light brown Caucasian hair strands. The hair strands were washed manually stepwise 30 times and the colour loss compared with the results obtained on wool tissues using an automatic application system. For most of the investigated hair colours, a coefficient of determination of r2 > 0.99 was achieved. Modern permanent hair colours show a high resistance to cosmetic treatments. Over 90% of the initial colour result was retained after 30 product applications. Shampoo and conditioner formulations induce different degrees of colour loss in hair. In basic formulas significant influences of single surfactants could be detected. The new method using wool tissues correlates very well with that using manually washed Caucasian hair strands. This automatic method is very time‐effective and offers an excellent reproducibility with a high sensitivity for assessing product influences on artificial hair colours. Keywords: Color fading, color protection, color retention, hair color resistance, hair wash simulation Paper presented at the IFSCC Conference 2007, Amsterdam, The Netherlands     

Praxisorientierte Raffination von Stahlschmelzen mit Seltenerdmetallen

Simulation eines pfannenmetallurgischen Stahlraffinationsverfahrens unter Verwendung von Cer-Mischmetall, einer Raffinationsschlacke und Argonspülung zur Reinheitsgradverbesserung. Darstellung typischer nichtmetallischer Einschlüsse. Aufzeigen der erzielten Zähigkeitsverbesserungen und der Verringerung der Zähigkeitsanisotropie.     

Electron-transfer reactions at semiconducting anodic niobium oxide films

Anodic niobium oxide in a n-type semiconductor due to an oxygen deficit. Electron donor densities and the dependence of excitation energies upon donor density were determined from measurements of space-charge capacitances as a function of electrode potential. Rates of Fe(III) reduction and of Fe(II) oxidation were measured at oxide films of different donor densities as functions of electrode potential and pH value. The results indicate electronic states in the space-charge layer below the oxide surface to participate in the electron-transfer reactions. Experimental polarisation curves are compared to curves calculated theoretically. From the shape of the polarisation curve flat-band potentials of the oxide are estimated. The observed polarisation curves are compatible with λ = 1·2 eV for the reorganisation energy of the Fe(CN)^3?₆/Fe(CN)^4?₆ redox couple.     

Analysis of the temperature dependence of the fracture stress of sharp notched bending specimens of a structural steel with respect to intermediate transitions

The flow and fracture stresses, σ_y^g and σ_f^g (δ = crack tip displacement), of sharply notched bending specimens of a structural steel U St 37-1 are measured in the temperature range from full scale to small scale yielding. The best adaption of the experimental results for σ_f^g is obtained by a curve which exhibits an intermediate transition, i.e. which follows in a temperature range between an upper, T_tM¹ and a lower, T_tl¹, transition temperature to the curve σ_y^g(T) for the flow stress with a constant δ = δ₁. This transition corresponds to that of the slip to the twin nucleated fracture. Two analyses [3,5] according to the local fracture stress, σ_f^*, concept show that the amount and the temperature dependence of σ_f^* are somewhat different for both methods, but that both exhibit an increase of σ_f^* in the transition range. It is concluded that each transition in the nucleation mode of the fracture is connected with such a transition in the fracture stress. It may, however, become indistinct or even be covered by the scatter of the experimental points.     

Determination of mechanical properties of slip cast, micro powder injection moulded and microcast high aspect ratio microspecimens

In a project of the German Research Council (DFG) Collaborative Research Centre (SFB) 499 Development, production and quality assurance of moulded micro-components made of metallic and ceramic materials [SFB03] three-point bending-specimens (dimension: 1.2 × 0.2 × 0.2 mm) made of slip cast [BAU02] or micro powder injection moulded ZrO₂ [RUP03] as well as tensile specimens (dimension of the gauge length: 0.78 × 0.26 × 0.13 mm) made of the micro-cast AuAgCu-alloy Stabilor G [BAU03] were investigated with respect to their behaviour under quasi-static loading.The support of the Deutsche Forschungsgemeinschaft is gratefully acknowledged. The authors appreciate the co-operation of all the project partners within the SFB 499.     

Accuracy and precision of manual baseline determination

Vibrational spectra often require baseline removal before further data analysis can be performed. Manual (i.e., user) baseline determination and removal is a common technique used to perform this operation. Currently, little data exists that details the accuracy and precision that can be expected with manual baseline removal techniques. This study addresses this current lack of data. One hundred spectra of varying signal-to-noise ratio (SNR), signal-to-baseline ratio (SBR), baseline slope, and spectral congestion were constructed and baselines were subtracted by 16 volunteers who were categorized as being either experienced or inexperienced in baseline determination. In total, 285 baseline determinations were performed. The general level of accuracy and precision that can be expected for manually determined baselines from spectra of varying SNR, SBR, baseline slope, and spectral congestion is established. Furthermore, the effects of user experience on the accuracy and precision of baseline determination is estimated. The interactions between the above factors in affecting the accuracy and precision of baseline determination is highlighted. Where possible, the functional relationships between accuracy, precision, and the given spectral characteristic are detailed. The results provide users of manual baseline determination useful guidelines in establishing limits of accuracy and precision when performing manual baseline determination, as well as highlighting conditions that confound the accuracy and precision of manual baseline determination.     

Photoeffects in ZnSiP2

Photoconductive and photovoltaic effects have been studied in n-type ZnSiP₂ platelets prepared from the vapor phase. The spectral responses extend from 1.5 eV to beyond 3.1 eV with peak signals in the 2.2-2.7 eV interval. Intrinsic (band-to-band) photoexcitation occurs at all energies, arising from the shallow energy dependence of the optical absorption edge. Trapping effects limit the photoconductive response time to 4xl0^-3sec. Peak spectral responsivity and detectivity values of 840 V/W and 9.5xl0⁹cm Hz 1/2 W⁻¹respectively are found for one sample.     

Homogenization and crystallization of histidine ammonia-lyase by exchange of a surface cysteine residue

Histidase (histidine ammonia-lyase, EC 4.3.1.3) from Pseudomonasputida was expressed in Escherichia coli and purified. In theabsence of thiols the tetrameric enzyme gave rise to undefinedaggregates and suitable crystals could not be obtained. Thesolvent accessibility along the chain was predicted from theamino acid sequence. Among the seven cysteines, only one waslabeled as `solvent-exposed'. The exchange of this cysteineto alanine abolished all undefined aggregations and yieldedreadily crystals diffracting to 1.8 Å resolution.