Applications of ATR-FTIR spectroscopic imaging to biomedical samples

FTIR spectroscopic imaging in ATR (Attenuated Total Reflection) mode is a powerful tool for studying biomedical samples. This paper summarises recent advances in the applications of ATR-FTIR imaging to dissolution of pharmaceutical formulations and drug release. The use of two different ATR accessories to obtain chemical images of formulations in contact with water as a function of time is demonstrated. The innovative use of the diamond ATR accessory allowed in situ imaging of tablet compaction and dissolution. ATR-FTIR imaging was also applied to obtain images of the surface of skin and the spatial distribution of protein and lipid rich domains was obtained. Chemical images of cross-section of rabbit aorta were obtained using a diamond ATR accessory and the possibility of in situ imaging of arterial samples in contact with aqueous solution was demonstrated for the first time. This experiment opens an opportunity to image arterial samples in contact with solutions containing drug molecules. This approach may help in understanding the mechanisms of treatment of atherosclerosis.     

Investigation of the spinnability of cellulose/alkaline ferric tartrate solutions

Dynamic rheology, UV/VIS spectrometry with temperature programming cuvette and reaction calorimetry were conducted on cellulose pulp/FeTNa (NaOH solution containing ferric tartaric acid complex) solutions to investigate their thermostability and spinnability. Color of cellulose/FeTNa solutions changed above 90 °C due to the decomposition of the complex. Thermal activity of cellulose/FeTNa solution started above 130 °C induced by water vapor evolution and complex decomposition. Regeneration of cellulose/FeTNa solutions in a non-solvent (acetic acid and Na-gluconate mixture) resulted in transition from cellulose I into cellulose II structure as revealed by WAXS measurements. Wet-spinning attempts of cellulose/FeTNa solutions yielded fiber-like shaped bodies with a brittle structure.     

Influence of bacteria and salinity on diatom biogenic silica dissolution in estuarine systems

Dissolution of diatom biogenic silica (bSiO₂) in estuaries and its control by water salinity and bacteria were investigated using the river euryhaline species Cyclotella meneghiniana as a model. Laboratory-controlled bioassays conducted at different salinities with an estuarine bacteria inoculum showed a faster dissolution of diatom bSiO₂ at the lowest salinity where bacteria were the most abundant. However in another experiment, salinity increase clearly enhanced the dissolution of cleaned frustules (organic matter free). The presence of active bacteria might therefore predominate on the effect of salinity for freshly lysed diatoms whereas salinity might rather control dissolution of organic-matter-free frustule remains. Incubation of cultivated diatoms at different protease concentrations revealed that high proteolytic activities had little effect on bSiO₂ dissolution at a 1-month scale in spite of an efficient removal of organic matter from the frustules. Altogether it is hypothesized that bacterial colonization increases bSiO₂ dissolution by creating a microenvironment at the diatom surface with high ectoproteolytic activity but also via the release of metabolic byproducts since the presence of organic matter seems generally to facilitate diatom bSiO₂ dissolution.     

Chemical modification of xanthan gum to increase dissolution rate

Xanthan gum is modified with formaldehyde to improve the dissolution rate. The FT-IR spectra and the X-ray diffraction spectra both show that chemical modification reduces intermolecular interactions and crystallinity. Viscosity measurements show that the chemically modified gum dissolves more rapidly than before.     

‘The Family of Denmark’ and ‘the Aliens’: Kinship Images in Danish Integration Politics

More than broadly agreeing on the need for a critical deconstruction of the very foundations of anthropological theory and practice aimed at uncovering the elements implicitly excluded from analysis, the silences in a reasoning process and the blind spots in observations, the author stresses need to distinguish between this kind of deconstruction, which is positive and essential for any knowledge-building activity, and another deconstruction which can lead to hyper-relativism. The second tendency, baptized 'postmodernism' and highly popular in the USA, is a largely overblown enterprise of deconstructive dissolution which, if carried to its logical conclusion, threatens to submerge social anthropology in the rising tide of 'Cultural Studies'. Postmodernist theory is a somewhat eclectic mixture of (often contradictory) ideas borrowed from such French thinkers as Foucault, Derrida and Lyotard, which is advanced in support of the idea that a 'science of man', in other words, a set of systematic observations, analyses and findings subjected to testing and verification, is not possible. The author here explains why he takes the opposite view.     

High-throughput system for determining dissolution kinetics of inclusion bodies

Efficient solubilization is a crucial step during inclusion body processing and dissolving conditions were usually empirically established. Here we describe a new methodology for rapid screening of solubilization conditions and evaluation of dissolution kinetics in microtiter plates. Increase of protein in solution over time was directly related to decrease of turbidity measured by absorbance at 600 nm. Dissolution kinetics of inclusion bodies were described by a first-order reaction kinetics, which was used for drug dissolution modeling. Reaction constants were in the range of 0.01–0.03 s^–1 for buffer conditions providing sufficient solubilization power. This method is not limited to the screening of optimal buffer conditions for solubilization and can be applied for studying other parameters involved in the solubility of IBs, such as pI of the protein, influence of fermentation conditions, influence of initial protein concentration, and more.     

Modeling of DNAPL-Dissolution,Rate-Limited Sorption and Biodegradation Reactions in Groundwater Systems

This article presents an approach for modeling the dissolution process of single component dense non-aqueous phase liquids (DNAPL), such as tetrachloroethene and trichloroethene, in a biologically reactive porous medium. In the proposed approach, the overall transport processes are conceptualized as three distinct reactions. Firstly, the dissolution (or dissolving) process of a residual DNAPL source zone is conceptualized as a mass-transfer limited reaction. Secondly, the contaminants dissolved from the DNAPL source are allowed to partition between sediment and water phases through a rate-limited sorption reaction. Finally, the contaminants in the solid and liquid phases are allowed to degrade by a set of kinetic-limited biological reactions. Although all of these three reaction processes have been researched in the past, little progress has been made towards understanding the combined effects of these processes. This work provides a rigorous mathematical model for describing the coupled effects of these three fundamental reactive transport mechanisms. The model equations are then solved using the general-purpose reactive transport code RT3D (Clement, 1997).     

Protein and ligand enhanced dissolution of BeO at pH 7

Be is a toxic metal used in both aerospace and defense industries. Lung exposure to Be can lead to a specific immune response called chronic beryllium disease (CBD). CBD has the unique characteristics that it can be triggered by very low level exposures, yet the onset of systems can be delayed from one to over 20 years. This variable delay in the onset of systems implies that a change in the local environment leads to dissolution and bio-availability of the particulate Be. We report here on the dissolution of the highly insoluble BeO in the presence of known Be ligands including the iron transport protein, transferrin, and the ubiquitous citric acid. The presence of ligands even at the 100 μM level led to dissolution of Be to levels that have been shown to cause immune response in both the blood and the lung. Dissolution occurred at pH 7 and was significantly enhanced in a 10 mM phosphate buffer.     

Potential application of a low-viscosity and high-transparency xanthan gum produced from Xanthomonas campestris CCTCC M2015714 in foods

Xanthan gum is commonly used as a thickener in food industry, while the usage of xanthan gum as a dietary fiber is restricted for its low additive volume. Herein, the potential use of a low-viscosity and high-transparency xanthan gum as a dietary fiber was evaluated in vitro. This new xanthan shows better transparency and faster dissolution rate than most commercial products, and its viscosity increases along with the treatment of freeze–thaw cycles at ?20°C. Moreover, this new xanthan can absorb heavy metals (Pb, Cd, Cu) and retard starch digestion by glucoamylase. In summary, this new xanthan could be potentially used as a dietary fiber or fiber ingredient for preventing and treating diabetes, hyperlipemia, heavy metal poisoning, and cardiovascular diseases effectively.