Some Observations on the Effect of Urea on the Dyeing Behaviour of Wool at Low Temperatures

The effect of adding urea to the dyebath on the rate of absorption of reactive and acid dyes by wool, and of acid dyes by other protein bres, has been studied. Possible modesof action of aqueous solutions of urea on wool are discussed. The observed increase in the ite of dyeing in the presence of urea is due to disaggregation of the dye in solution and reduction in dye-protein hydrophobic interactions. The action of urea in promoting fibre swelling is also likely to be a contributory factor.     

Oxidative thermal decomposition of poly(vinyl chloride) compositions

“Pure” poly(vinyl chloride) resin and four compositions containing poly(vinyl chloride) were subjected to oxidative thermal degradation in air at &400°C both in a quiescent and a flow system. The volatiles formed were identified and quantitatively determined on a gram-per-gram basis. Hydrogen chloride was the main product found. The nature and relative concentration of the produced organic chlorinated species appeared to be dependent not only on the poly(vinyl chloride) constituent but also on the other ingredients. All the compositions contained phthalate ester plasticizers. In the dynamic system, these distilled largely unchanged, whereas under static conditions transformation into phthalic anhydride occurred.     

Specificity of the pheromone system ofAdoxophyes orana andClepsis spectrana

The pheromone system of the summer fruit tortrix mothAdoxophyes orana (Fischer von Röslerstamm) consists of a mixture ofcis-9- andcis-11-tetradecen-1-ol acetate (cis-9- andcis-11-TDA, respectively) in a ratio of 9:1. Substitution of one or both of these compounds by related unsaturated acetates reduced the attractancy. Onlycis-11-TDA could be replaced bycis-11-tridecen-1-ol acetate (cis-11-TriDA), although the 9:1 mixture ofcis-9-TDA andcis-11-TriDA was less attractive in the field than the pheromone system itself. The major component of the pheromone system of the leaf rollerClepsis spectrana (Treitschke)(cis-9-TDA:cis-11-TDA=1:9) could also be replaced bycis-11-TriDA, again with some reduction in attractancy.     

Diffusion coefficient in polymer solutions

Molecular diffusivity of a solute in a solvent may be determined by measuring the extent of dispersion of solute in solvent flowing in a straight circular tube under the conditions of laminar flow. This simple and rapid method for determination of molecular diffusivity in aquous polymer solutions is discussed. Experimental results show a substantial reduction in the solute diffusivity with increase in polymer concentration.     

Vertical pneumatic conveying: An experimental study with particles in the intermediate and turbulent flow regimes

Vertical pneumatic conveying was studied in a 3-inch diameter riser 30 feet in length using solids ranging in particle Reynolds number from 100 to 3500. Particle to gas mass flow ratios varied from 0 to 8 and pipeline conditions extended from dilute flow down into the choking region. Average particle hold-up was determined by means of a series of quick-closing valves and particle slip velocity was often found to be greater than the calculated terminal velocity. The reasons for this are examined. Frictional pressure losses in the riser were also determined and compared with literature data. The phenomenon of choking is considered briefly.     

Towards properly controlled analytical measurement methods

It is of great practical importance to develop simple methods for the automatic detection ofthe controlled state of the analytical method being applied. The key point is to find quantities that greatly affect the quality of the analytical results and that can be easily estimated during the measurement process from the measured data. The signal-to-noise ratio has proved to be such a quantity in gas chromatographic methods. The statistical properties of the estimation of the signal-to-noise ratio from gas chromatographic data have been investigated. The suggested practical method for estimating the signal-to-noise ratio proved to be biased from a mathematical statistical point of view, but the bias is usually not greater than 10%. It has been shown by practical examples that the signal-to-noise ratio affects the quality of the analytical results and it is easy to estimate its value from practical data.