Non-aqueous extraction of Alberta oil sands is of great interest to developing an alternative to the current hot-water extraction process to eliminate the tailing ponds. Investigations have been conducted to evaluate the performance of solvent mixtures to extract bitumen from a high-grade oil sands ore. Solvent mixtures of cycloalkane and n-alkanes were studied on the basis of their Hildebrand solubility parameters, which affect bitumen recovery and fine solids migration during the extraction process, and the results were compared to single solvents. Cyclohexane, cyclopentane, and methylcyclopentane were selected as the cycloalkane solvents, and they were studied in combination with n-alkane solvents, such as n-heptane, n-hexane, or n-pentane, to make up a final solubility parameter between 16.65 and 16.45 MPa1/2 for the final solvent mixture. It was observed that the solubility parameter of the solvent mixture has more impact on the migration of fine solids in bitumen than the recovery of bitumen. The amount of fine solids migrating into the bitumen product followed the order of cycloalkane/n-heptane > cycloalkane/n-hexane > cycloalkane/n-pentane.

Raman and mid-infrared (MIR) spectroscopy are useful tools for the specific detection of molecules, since both methods are based on the excitation of fundamental vibration modes. In this study, Raman and MIR spectroscopy were applied simultaneously during aerobic yeast fermentations of Saccharomyces cerevisiae. Based on the recorded Raman intensities and MIR absorption spectra, respectively, temporal concentration courses of glucose, ethanol, and biomass were determined. The chemometric methods used to evaluate the analyte concentrations were partial least squares (PLS) regression and multiple linear regression (MLR). In view of potential photometric sensors, MLR models based on two (2D) and four (4D) analyte-specific optical channels were developed. All chemometric models were tested to predict glucose concentrations between 0 and 30 g L−1, ethanol concentrations between 0 and 10 g L−1, and biomass concentrations up to 15 g L−1 in real time during diauxic growth. Root-mean-squared errors of prediction (RMSEP) of 0.68 g L−1, 0.48 g L−1, and 0.37 g L−1 for glucose, ethanol, and biomass were achieved using the MIR setup combined with a PLS model. In the case of Raman spectroscopy, the corresponding RMSEP values were 0.92 g L−1, 0.39 g L−1, and 0.29 g L−1. Nevertheless, the simple 4D MLR models could reach the performance of the more complex PLS evaluation. Consequently, the replacement of spectrometer setups by four-channel sensors were discussed. Moreover, the advantages and disadvantages of Raman and MIR setups are demonstrated with regard to process implementation.

In this report, a quantitative nicotinamide adenine dinucleotide hydrate (NADH) fluorescence measurement algorithm in a liquid tissue phantom using a fiber-optic needle probe is presented. To determine the absolute concentrations of NADH in this phantom, the fluorescence emission spectra at 465 nm were corrected using diffuse reflectance spectroscopy between 600 nm and 940 nm. The patented autoclavable Nitinol needle probe enables the acquisition of multispectral backscattering measurements of ultraviolet, visible, near-infrared and fluorescence spectra. As a phantom, a suspension of calcium carbonate (Calcilit) and water with physiological NADH concentrations between 0 mmol l−1 and 2.0 mmol l−1 were used to mimic human tissue. The light scattering characteristics were adjusted to match the backscattering attributes of human skin by modifying the concentration of Calcilit. To correct the scattering effects caused by the matrices of the samples, an algorithm based on the backscattered remission spectrum was employed to compensate the influence of multiscattering on the optical pathway through the dispersed phase. The monitored backscattered visible light was used to correct the fluorescence spectra and thereby to determine the true NADH concentrations at unknown Calcilit concentrations. Despite the simplicity of the presented algorithm, the root-mean-square error of prediction (RMSEP) was 0.093 mmol l−1.

Multimodal imaging gains increasing popularity for biomedical applications. This article presents the design of a novel multimodal imaging system. The centerpiece is a light microscope operating in the incident and transmitted light mode. Additionally, Raman spectroscopy and VIS/NIR reflectance spectroscopy are adapted. The proof-of-concept is realized to distinguish between grey matter (GM) and white matter (WM) of normal mouse brain tissue. Besides Raman and VIS/NIR spectroscopy, the following optical microscopy techniques are applied in the incident light mode: brightfield, darkfield, and polarization microscopy. To complement the study, brightfield images of a hematoxylin and eosin (H&E) stained cryosection in the transmitted light mode are recorded using the same imaging system. Data acquisition based on polarization microscopy and Raman spectroscopy gives the best results regarding the tissue differentiation of the unstained section. In addition to the discrimination of GM and WM, both modalities are suited to highlight differences in the density of myelinated axons. For Raman spectroscopy, this is achieved by calculating the sum of two intensity peak ratios (I2857 + I2888)/I2930 in the high-wavenumber region. For an optimum combination of the modalities, it is recommended to apply the molecule-specific but time-consuming Raman spectroscopy to smaller regions of interest, which have previously been identified by the microscopic modes.

Fluorescence emission intensity is an important indicator for characterising tissue. This study extends our previous work and presents an algorithm to determine the absolute nicotinamide adenine dinucleotide hydrate (NADH) concentration of a liquid tissue model with the aid of a multispectral needle probe. Besides the scattering correction, this newly developed algorithm has the ability to compensate the absorbance effects of the tissue model. As an absorber new coccine (NC) is used to mimic the haemoglobin’s absorbance of human tissue, while Calcilit imitates the tissue’s scattering. The algorithm’s bases are the differences between two definite integrals of the absorbance remission and the fluorescence emission spectrum, respectively. Using this simple mathematic model, an algorithm to determine NADH concentrations between 0.5 and 2.0 mM at 2.7 wt% Calcilit and NC concentrations between 0.252 and 2.520 mM is successfully tested. This results in a mean absolute percentage error (MAPE) of 0.3% for the calculation of the Calcilit concentration and MAPEs of 3.3 and 5.0% to determine the fluorophore concentration.