Polyisocyanate Shrink-resist Treatments for Wool: A Mechanistic Study

The Flory-Stockmayer approach to polymer gelation or network theory has been applied to the moisture curing of polyisocyanates used to shrink-resist wool. This predicts that polyisocyanates of functionality f gel at an extent of reaction of(f-l)^-1. This was confirmed experimentally and the relation was shown to be independent of the initial concentration of water and the presence of catalysts. The development of shrink-resistance on wool treated with polyisocyanates has been related to their gel-point and the extent of crosslinking after gelation. The properties of wool treated with some di- and tri-functional polyisocyanates have been compared and the results interpreted using network theory and kinetic factors involved in the curing reaction. The optimum functionalities for use on wool of polyisocyanates derived from polypropylene oxide polyols and various di-iso-cyanates are discussed.     

LANASOL(R)染料比媒介染料更适用于羊毛染色

欧洲化学品管理局(ECHA)现已将重铬酸盐列入了高关注物质(SVHC)的名单.用含有重铬酸钾和重铬酸钠等的媒介染料染制羊毛的工厂正面临着越来越大的压力.这意味着采用这种技术的染厂未来可能要得到特别授权才能使用这种化学品.     

Charge transport in cellular nanoparticle networks: meandering through nanoscale mazes

The transport of electrons through topologically complex two-dimensional Au nanoparticle networks has been investigated using a combination of low temperature (4.5 K) direct current I(V) measurements and numerical simulations. Intricate, spatially correlated nanostructured networks were formed via spin-casting. The topological complexity of the nanoparticle assemblies produces I(V) curves associated with nonlinearity exponents, zeta approximately 4.0. Simulations based on tunneling transport in sparse and inhomogeneous planar networks are used to elucidate the influence of topology on the value of zeta.     

Sizing dielectric spheres and cylinders by aligning measured and computed resonance locations: algorithm for multiple orders

An algorithm for determining the size of dielectric spheres and cylinders by aligning measured and computed resonance locations is presented. The orders of the resonance locations need not be known a priori. The algorithm is applicable to several types of scattering and emission spectra of spheres and cylinders if the index of refraction including dispersion is known and uniform, or nearly uniform, throughout the sphere or cylinder. The algorithm performs well when tested with groups of computed resonance locations of spheres (synthetic data) and with measured fluorescence emission spectra of spheres exhibiting as many as 5 orders of resonance.     

A state-space approach to optimum postfiltering of sampled data

In this paper, we apply state-space techniques to the problem of reconstructing a random continuous-time waveform from its discrete-time samples. The optimal zero-lag filter that accomplishes this is well known, but to our knowledge the smoothing problem has not been previously considered in this context. We develop smoothing algorithms in the mixed-time framework appropriate to the interpolation problem, and then compare our results with those obtained previously in discrete time. Our results are related to those previously obtained in a simple and intuitive way, and the required computations are straightforward modifications of those described previously for purely discrete and purely continuous time.     

Ferroelectric polymer gates for non-volatile field effect control of ferromagnetism in (Ga, Mn)As layers

(Ga, Mn)As and other diluted magnetic semiconductors (DMS) attract a great deal of attention for potential spintronic applications because of the possibility of controlling the magnetic properties via electrical gating. Integration of a ferroelectric gate on the DMS channel adds to the system a non-volatile memory functionality and permits nanopatterning via the polarization domain engineering. This topical review is focused on the multiferroic system, where the ferromagnetism in the (Ga, Mn)As DMS channel is controlled by the non-volatile field effect of the spontaneous polarization. Use of ferroelectric polymer gates in such heterostructures offers a viable alternative to the traditional oxide ferroelectrics generally incompatible with DMS. Here we review the proof-of-concept experiments demonstrating the ferroelectric control of ferromagnetism, analyze the performance issues of the ferroelectric gates and discuss prospects for further development of the ferroelectric/DMS heterostructures toward the multiferroic field effect transistor.     

Randomised double blind trial of morphine versus diamorphine for sedation of preterm neonates

AIMS: To compare the safety and effectiveness of morphine and diamorphine for the sedation of ventilated preterm neonates in a double blind, randomised trial. METHODS: Eighty eight babies were allocated to receive either morphine (n = 44) or diamorphine (n = 44) by bolus infusion (200 or 120 mcg/kg, respectively, over two hours), followed by maintenance infusion (25 or 15 mcg/kg/h, respectively) during the initial phase of their respiratory disease. Serial monitoring of physiological, behavioural, and biochemical variables over the first 24 hours of the infusions was performed. Longer term outcomes were also monitored. RESULTS: Morphine, but not diamorphine, was associated with a mean (SEM) decrease in mean arterial blood pressure of 2.2 (1.0) mm Hg (p = 0.05) over the initial loading infusion. Physiological (blood pressure variability) and behavioural measures of sedation (clinical assessment and sedation scoring) indicated that the two drug regimens were equally effective after 24 hours, but the sedative effects of diamorphine were evident more quickly than those of morphine. Both regimens significantly reduced plasma adrenaline concentrations over the first 24 hours of the infusions. No significant differences in mortality, ventilator days, chronic lung disease or intracranial lesions were noted. CONCLUSIONS: Both drug regimens reduce the stress response to ventilation in preterm neonates. However, diamorphine's more rapid onset of sedation and morphine's hypotensive tendency suggest that diamorphine is preferable for the sedation of mechanically ventilated preterm neonates.     

Structural Studies of Shrink-resist Polymers for Wool: Polyisocyanates from a Polypropylene Oxide Triol and Different Di-isocyanates

Polyisocyanates were prepared from a polypropylene oxide triol (mol. wt 3000) and various di-isocyanates, applied to wool fabrics, and moisture-cured. The shrink-resist effectiveness decreased as the rate of moisture curing of the poly-isocyanate increased. The stability of the cured polymer to thermal- and photo-degradation was much higher with polyisocyanates from aromatic than with those from aliphatic di-isocyanates. The shrink-resist effectiveness was reduced in the presence of catalysts. An explanation is proposed for the observed differences in shrink-resist effectiveness based on differences in the extent of cross-linking in the cured polymer.     

Structural Studies of Shrink-resist Polymers for Wool: The Influence of Molecular Weight and Functionality in Polypropylene Oxide Polyisocyanates

A series of polypropylene oxide diols and triols of different molecular weights was reacted with excess hexamethylene di-isocyanate to form polyisocyanates. These polymers were applied to wool, steam-cured, and examined in shrink-resist and durable-press treatments. Some difunctional polymers were effective in shrink-resisting wool even though the cured polymer should be essentially uncrosslinked. This was attributed to interchain hydrogen bonding in the cured polymer. Optimum ranges for the functionality and molecular weight of this type of polymer for use on wool are discussed.