Flame-retardant cotton fabrics by reaction of cellulose with phosphorus trichloride–DMF adduct

Cotton sateen fabric was found to react with the 1 : 2 adduct of phosphorus trichloride and N,N-dimethylformamide (DMF) in DMF or DMF—chloroform solutions at room temperature. During this reaction, the fabric acquired flame resistance. The introduction of as little as 1.2% phospohorus and 0.4% nitrogen, achieved at adduct concentrations as low as 2–5% in reaction times of 5–30 min, was sufficient to impart a useful level of flame retardancy. The effect of the adduct concentration, reaction time, and wash procedures on the flame resistance and other properties of the resultant cotton fabrics was studied. Moderate increases in the wet and dry wrinkle recovery were imparted by the treatment, but the use of high concentrations of adduct were somewhat detrimental to the tensile strength of the fabric. However, adduct concentrations of 20–25% produced a rather durable finish which passed the standard vertical flame test after 20 home launderings. Gradual loss of flame resistance during repeated laundering is attributable to ion exchange properties gradually acquired by the fabric. Based on analytical and in frared spectral data, the initial reaction of cellulose with the PCl₃—DMF adduct is thought to involve elimination of one mole of DMF to form cellulose? O? P linkages, as well as some cellulose crosslinking via a second formimidate group of the adduct. Gradual hydrolysis during multiple launderings apparently yields cellulose acid phosphates responsible for the calcium ion uptake and decrease in flame resistance.     

Mine maintenance analysis through Markov chain schemes

ABSTRACT

This paper shows how Markov chain schemes can be used for analyzing equipment availability problems, forecasting the number of dozer engines replacements, studying hoist traffic pattern between various levels in an underground mine and modelling the occurence of good and defective idlers along a conveyor.     

Optimum specimen positioning in the electron microscope using a double-tilt stage

Optimal imaging of complex structures requires proper alignment relative to the optic axis of the electron microscope. This is especially important for high-voltage and intermediatevoltage microscopes, which form an in-focus image throughout the entire thickness of the object. As a result, structures at different specimen heights form overlapping and confused images that severely curtail the usefulness of these instruments. The work described here provides a generalized, flexible method for optimizing specimen orientation and eliminating or limiting image overlap by means of a commonly used double-tilt stage. Analysis of the motion about the two axes provides accurate tilting for any azimuthal direction whether or not it corresponds to a mechanical axis of the stage. An object can be positioned to minimize image overlap, to record stereopairs for any parallax axis, and to record three-dimensional data sets by the conical collection geometry. Images of muscle paracrystals are shown after tilting about an axis perpendicular to a symmetry direction. The tilted image displays higher-order symmetry, which is altered by changes of one degree. Precision double-tilting for optimizing stereopairs is shown for a desmosome recorded using different parallax axes and pretilts. A tomographic conical data-collection scheme is demonstrated by imaging a microtubule axoneme for a specific cone half-angle and arbitrary azimuthal angles.     

L.A. County plans its disaster response.

The Los Angeles County Fire Department is one of many agencies making great strides in the development of urban search and rescue programs. Much of the department's USAR training, equipment, and strategies have been tested on real incidents. Each incident presents new challenges and teaches new lessons. Before the establishment of the three-tiered USAR system, those personnel nearest an incident handled it. Many never saw a similar incident again. The lessons they learned were often lost because there was no system to collect their experiences, retrieve the information, and make it available to other emergency responders in the form of training programs. A major advantage of tiered response is the system's ability to ensure rapid response by trained, experienced, and well-equipped personnel. Rather than repeating mistakes and forgetting successful rescue methods, the system allows the retrieval of the experiences of personnel and their use in the development of training materials. Urban search and rescue specialists have the ability to build on earlier experiences to raise the overall level of skills. The net result is more effective training, increased efficiency, and enhanced safety for rescuers and victims. The field of urban search and rescue is still in its infancy. Many new and innovative strategies, techniques, and tools are on the horizon. In recent years, there has been growing interest in this specialty across the nation. We expect this trend to continue as breakthroughs occur. More than ever, it is important for all concerned agencies to share information and to work together to improve our ability to save lives.     

Rental tenants’ willingness-to-pay for improved energy efficiency and payback periods for landlords

Throughout the developed world, residential buildings in the rental sector exhibit lower levels of energy efficiency than the owner-occupied building stock. This study estimates Irish rental tenants’ willingness-to-pay for energy efficiency improvements. A double-bounded dichotomous choice contingent valuation method is used to examine how much renters are willing to pay in their monthly rent for improved energy efficiency, measured via energy performance certificates. Using an administrative dataset from a grant scheme for residential energy efficiency retrofits, we examine the upfront cost to landlords of engaging in energy efficiency retrofits and calculate associated payback periods. Tenants in Ireland are willing to pay an average of €38 for a one-grade improvement along a 15-point energy performance certificate scale. Providing additional information about energy performance certificates and the potential impact on energy costs reduced mean willingness-to-pay, implying that in the absence of information tenants overvalued energy efficiency labels. Based on tenants’ willingness-to-pay, investment payback periods for attic and cavity wall insulation are relatively short but prohibitively long for external wall insulation and solar heating retrofits.     

The temporal dynamics of miniscleral contact lenses: Central corneal clearance and centration

Purpose

To examine the time course of the reduction in central corneal clearance and horizontal and vertical lens translation (decentration) during miniscleral contact lens wear and the theoretical influence upon the optics of the post-lens tear layer.

Dietary lecithin improves dressing percentage and decreases chewiness in the longissimus muscle in finisher gilts

The influence of dietary lecithin at doses of 0, 4, 20 or 80 g/kg fed to finisher gilts for six weeks prior to slaughter on growth performance, carcass quality and pork quality was investigated. M. longissimus lumborum (loin) was removed from 36 pig carcasses at 24 h post-mortem for Warner–Bratzler shear force, compression, collagen content and colour analyses. Dietary lecithin increased dressing percentage (P = 0.009). Pork chewiness and collagen content were decreased by dietary lecithin (P < 0.05, respectively), suggesting that improved chewiness may be due to decreased collagen content. However, dietary lecithin had no effect on shear force, cohesiveness or hardness (P > 0.05, respectively). Dietary lecithin reduced loin muscle L* values and increased a* values (P < 0.05, respectively) but no changes on b* values (P = 0.56). The data showed that dietary lecithin improved dressing percentage and resulted in less chewy and less pale pork.