Search results for "Absorption"
showing 10 items of 2701 documents
Investigations of Chl a aggregates cross-linked by dioxane in 3-methylpentane
1997
In this work, dioxane-bound aggregates of chlorophyll a are prepared in 3-methylpentane. The properties of the aggregates are studied by using steady-state and time-resolved spectroscopies. The Q -region absorption spectrum of the y chlorophyll a-dioxane aggregate shows four clearly resolvable narrow bands with comparable intensities. The band maxima are located at 683, 689, 698 and 702 nm. The emission spectrum consists of two emission bands centred at 699 and 702 nm suggesting the presence of two types of aggregates. High degree of fluorescence polarization is detected yielding the angles between the absorption transition moments with respect to the 702 nm emission transition moment. The …
Induced Chirality in Confined Space on Halogen Gold Complexes
2015
The solubilization of HAuCl4 in toluene within optically active reverse micelles and lamellar structures formed by (1R,2S)-Dodecyl(2-hydroxy-1-methyl-2-phenylethyl)- dimethylammonium bromide (DMEB) has allowed us to evidence the complex phenomenology accompanying the confinement of Au salt within these nanostructures. Together with a chloride/bromide exchange process occurring in the first coordination sphere of an Au ion, UV−vis and electronic circular dichroism (ECD) spectra reveal the appearance of an induced dichroic signal attributable to Au complexes entrapped in the hydrophilic domain of the DMEB chiral nanostructures. Interestingly, change of the effective oxidation state and coordi…
Nickel(II), copper(II) and zinc(II) metallo-intercalators: structural details of the DNA-binding by a combined experimental and computational investi…
2014
We present a thorough characterization of the interaction of novel nickel(II) (1), copper(II) (2) and zinc(II) (3) Schiff base complexes with native calf thymus DNA (ct-DNA), in buffered aqueous solution at pH 7.5. UV-vis absorption, circular dichroism (CD) and viscometry titrations provided clear evidence of the intercalative mechanism of the three square-planar metal complexes, allowing us to determine the intrinsic DNA-binding constants (K(b)), equal to 1.3 × 10(7), 2.9 × 10(6), and 6.2 × 10(5) M(-1) for 1, 2 and 3, respectively. Preferential affinity, of one order of magnitude, toward AT compared to GC base pair sequences was detected by UV-vis absorption titrations of 1 with [poly(dG-d…
Magnesium alloys (WE43 and ZE41) characterisation for laser applications
2004
International audience; One of the most important parameters in laser treatment is the quantity of beam energy absorbed by the substrate. Despite its important role played in laser processes, this factor is rarely available for the laser sources wavelengths and at high temperatures reached during such treatments. A series of experiments were carried out in order to characterise, from this point of view, two types of magnesium alloys, WE43 and ZE41, often used in laser applications (cladding, alloying, welding, etc.). The results represent an important step in order to understand Mg-alloys behaviour under laser beam action.
Permeability and toxicological profile estimation of organochlorine compounds by biopartitioning micellar chromatography
2008
This paper points out the usefulness of biopartitioning micellar chromatography (BMC) as a high-throughput primary screening tool providing key information about the oral absorption, skin permeability (Kp), brain–blood distribution coefficient (BB) and ecotoxicological parameters such as median lethal concentration (LC50) and bioconcentration factors of 15 organochloride compounds. The retention data of compounds in BMC conditions were interpolated in previously developed quantitative–retention activity relationships by our research group. Results show that the compounds studied readily cross the intestinal barrier (oral absorption >ercnt;) and the blood–brain barrier (log BB >p;0.4). In ad…
Digestive disorders and Intestinal microbiota
2018
In the last decade, a barge body of scientific literature has suggested that specific alterations of the gut microbiota may be associated with ther development and clinical course of several gastrointestinal diseases, including irritable bowel syndrome, inflammatory bowel disease, celiac disease, gastrointestinal cancer and Clostridium difficile infection. These alterations are often referred to as “dysbiosis”, a generic term designing reduction of gut microbiota biodiversity and alterations in its composition. Here, we provide a synthetic overview of the key concepts on the relationship between intestinal microbiota and gastrointestinal diseases, focusing on the translation of these concep…
Localized Surface Plasmon Resonance in Colloidal Copper Sulphide (Cu2-xS, x = 0 ≤ x < 1) Nanocrystals and Its Applications
2021
Colloidally prepared copper sulphide (Cu2-xS) nanocrystals are possessing superior structural and optical properties owing to the presence of copper vacancies. The application of colloidal Cu2-xS nanocrystals are critically analysed for several optoelectronic applications. Furthermore, colloidally prepared Cu2-xS nanocrystals undergo facile process such as cation exchange, additives induced structural modifications etc. Therefore, it is important to evaluate the optical properties of these nanomaterials in order to apply them for future optoelectronic applications. Out of other properties, localized surface plasmon resonance (LSPR) by controlling composition of the Cu2-xS nanocrystals is in…
Preclinical models for colonic absorption, application to controlled release formulation development.
2018
Oral controlled release (CR) formulations have many benefits and have become a valuable resource for the local and systemic administration of drugs. The most important characteristic of these pharmaceutical products is that drug absorption occurs mainly in the colon. Therefore, this review analyses the physiological and physicochemical features that may affect an orally administered CR product, as well as the different strategies to develop a CR dosage form and the methods used to evaluate the formulation efficacy. The models available to study the intestinal permeability and their applicability to colonic permeability determinations are also discussed.
The short-circuited everted sac of rat colon mucosa.
1981
A short-circuited preparation of everted rat colon sacs is described. The serosal current electrode is a AgAgCl wire. A cylindrical agar bridge or AgAgCl electrode may be employed on the mucosal side. Effects of Ag+ ions liberated from the electrodes on ion transport could not be demonstrated. Fluid and sodium are absorbed and bicarbonate secreted. Potassium and chloride movements are not significantly different from zero. The preparation remains stable for at least 2 h. Sodium absorption is diminished by 50% and bicarbonate secretion abolished in the absence of glucose. In principle, similar ion transport properties were found as in Ussing-chamber preparations. The advantage of the everted…
Evaluation of sewage sludge-based compost by FT-IR spectroscopy
2006
The aerobic batch composting fermentations of sewage sludge with wood chips and maturity compost as co-composting additives were carried out in an open type lab-scale reactor. Fourier transform infrared spectroscopy (FT-IR) spectroscopy was used to monitor the composting process, evaluate the degradation rate and thus determine the maturity. Although the composition of the input mixture strongly affects the shape of the infrared (IR) spectra, typical bands of components can be selected and used to follow the composting process. The appearance, shape and intensity of the nitrate band at 1384 cm 1 was well pronounced and evident for a sewage sludgebased compost maturity. An increase of the pe…