Alteration of the Optical and Mechanical Characteristics of Cellulose Nanofibre Films Under Thermal Treatment

Nanocelluloses and their different designs, such as films and nanopapers, have gained considerable interest in many application areas due to their unique properties. For many purposes, such as for packaging and electronics, the thermal stability of nanocellulose materials is a crucial characteristic. In this study, the effects of heat treatment (100ºC, 150ºC and 200ºC) on the optical and mechanical properties of 2,2,6,6-tetramethylpiperidinyl-1-oxy radical-oxidised cellulose nanofibre (TO-CNF) films were investigated, especially the alteration of the colour, complex refractive index and birefringence of the films. Exposing TO-CNF films to high temperatures (> 150ºC) induced permanent transformations in the CNF structure, leading to an increase in the refractive index, decreases in the birefringence and crystallinity index, colour darkening and significant deterioration of the mechanical properties.

An improved colorimetric procedure for the analysis of vitamin A

Factors affecting the reaction between antimony trichloride and 2,3-dichloropropanol (2,3-DP) with retinol and related compounds were examined. It is shown that purified 2,3-DP with the addition of antimony trichloride produces a stable colour complex with retinol absorbing at 555 nm. A tentative scheme for the reaction mechanism and the possible structure of the complex are also presented.

SPECTROFLUORIMETRY OF OESTROGENS: APPLICATION OF CORRECTION METHODS WHEN THE UNFILTERED WOLFRAM CONTINUUM IS USED AS ACTIVATING LIGHT

ABSTRACT The application of the wolfram continuum as activating light in spectrofluorimetry of oestrogens has been examined using oestrone as a model substance. When primary filters were omitted, the scatter, deriving from the incident beam, formed a continuous background over which the fluorescence spectra could be recorded in their full extension. In quantitative determinations, fluorescent light could be differentiated by application of correction equations based on recordings of the intensities of narrow spectral bands at the wave lengths of maximal specific emission and at one or two additional wave lengths. When correction methods were to be applied under the conditions examined, the procedure of Ittrich (1958) for colour development and extraction was found to offer the highest sensitivity. The correction equations used in fluorimetry of the Kober colour complex (in methylene chloride) were Fcorr = 2 F 548 mμ − (F 518 mμ + F 578 mμ) according to Allen (1950) or Fcorr = F 548 mμ − F 518 mμ where F represents light intensity units. The standard deviation of the corrected blank value in these methods corresponded to less than ± 0.2 ng oestrone.

ACID MUCOPOLYSACCHARIDES AND MAST CELLS IN THE BOVINE UTERUS AT DIFFERENT STAGES OF THE SEXUAL CYCLE

ABSTRACT The location and the content of acid mucopolysaccharides and mast cells in the bovine uterine wall were investigated during various stages of the sexual cycle. The histochemical location of the acid mucopolysaccharides revealed variations in the hue of the colour complex at different stages of the sexual cycle in various layers of the bovine uterine wall. This finding correlated with biochemical determination of the total amount of acid mucopolysaccharides and the hyaluronate fraction. Morphological examination of mast cells revealed their presence in greater number than was previously reported. Numerical variations of mast cells during the sexual cycle were noted and were parallel to the stainability and biochemical values, indicating hyaluronate.

UNTERSUCHUNGEN ÜBER DIE EXTRAKTION DES ROTEN KOBER-FARBSTOFFS DURCH ORGANISCHE LÖSUNGSMITTEL ZUR ÖSTROGENBESTIMMUNG IM HARN

ABSTRACT A series of organic solvents and phenol derivatives have been examined for the extraction of the pink Kober-colour complex. Optimal results could be achieved for fluorimetry by a solution of 2 % (w/v) p-nitrophenol and 1 % (v/v) ethanol in acetylenetetrabromide, when the green mercury line (546 mμ was used as primary light. The sensitivity, stability and specificity have been improved, compared with the previously described reaction. By changing the sequence of purification steps and by reducing the volume of the urine sample (5 ml) the method for the determination of total oestrogens has been simplified. Approximately 10 determinations can be done within 3–4 hours by one person. Recovery experiments and comparative determinations with a previously described method have been carried out. The excretion of total oestrogens in a complete menstrual cycle is determined with the described method.

SOME OBSERVATIONS ON THE SULPHURIC ACID COLOUR REACTION FOR THE ESTIMATION OF PREGNANEDIOL

SUMMARY When a solution of pregnanediol in concentrated sulphuric acid is heated at 25° C for 17 hr, the spectrum of the colour complex formed is different from the spectrum of pregnanediol diacetate similarly treated. The intensity of colour of such solutions increases rapidly for 8 hr. Thereafter the rate of increase slows down; maximum colour development is reached in 17–20 hr. At temperatures above 25° C the characteristic light absorption pattern of the steroid-acid solution becomes progressively obliterated. The intensity of colour is decreased by hydrogen peroxide and by barium nitrate; it is increased by sodium sulphite and hydroquinone. The same weight of pregnanediol may give different spectrophotometric readings if different stock samples of sulphuric acid are used. These differences may be greatly reduced by pretreating the sulphuric acid with sodium sulphite.