R. W. Kessler

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Decolorization of textile dyes by a laccase from Trametes modesta immobilized on gamma-aluminum oxide pellets was studied. An enzyme reactor was equipped with various UV/Vis spectroscopic sensors allowing the continuous online monitoring of the decolorization reactions. Decolorization of the dye solutions was followed via an immersion transmission probe.(More)
Fibre formation in hemp (Cannabis sativa L.) is a dynamic process. In order to follow this process, the chemical composition of the hemp stem was studied during plant development using the acid and neutral detergent fibre and lignin methods. Additionally, near infra-red spectroscopy was carried out. To predict the chemical composition of the stem samples(More)
The laccase-catalysed transformation of indigo carmine (IC) with and without a redox active mediator was studied using online UV-visible spectroscopy. Deconvolution of the mixture spectra obtained during the reaction was performed on a model-free basis using multivariate curve resolution (MCR). Thereby, the time courses of educts, products, and reaction(More)
In biotechnology, strong emphasis is placed on the development of wet chemical analysis and chromatography to separate target components from a complex matrix. In bioprocessing, the development of single compound biosensors is an important activity. The advantages of these techniques are their high sensitivity and specificity. Inline or online monitoring by(More)
Raman intensities from reflection (X(R)) and transmission (X(T)) setups are compared by calculations based on random walk and analytical approaches with respect to sample thickness, absorption, and scattering. Experiments incorporating strongly scattering organic polymer layers and powder tablets of pharmaceutical ingredients validate the theoretical(More)
Hot melt extrusion (HME) is a well-known process within the plastic and food industries that has been utilized for the past several decades and is increasingly accepted by the pharmaceutical industry for continuous manufacturing. For tamper-resistant formulations of e.g. opioids, HME is the most efficient production technique. The focus of this study is(More)
In continuation of our contribution to "The Axial Transfer" (Appl. Spectr. 2012. 66(8): 934-943), this paper describes the distribution of localized incident radiation in multiple scattering layers of arbitrary thickness and analyzes the lateral intensity profiles of radiation leaving the sample from its illuminated and non-illuminated surfaces. The(More)
The article presents two general equations of radiation penetration into layers of diffuse reflectors. One of the equations describes the depth origins of reflection, the other the depth profiles of absorption. The equations are evaluated within the theory of radiative transfer applying various degrees of analytical approximations and Monte Carlo(More)
One of the most often used tools in process analytical technology (PAT) is NIR spectroscopy as a non-destructive fast and reliable method to identify and quantify active pharmaceutical ingredients (API) in tablets. Very little work has been devoted to analyse the effects of scatter on quantitative analysis of the chemical composition. A novel approach to(More)
Current techniques for chromosome analysis need to be improved for rapid, economical identification of complex chromosomal defects by sensitive and selective visualisation. In this paper, we present a straightforward method for characterising unstained human metaphase chromosomes. Backscatter imaging in a dark-field setup combined with visible and short(More)