BackgroundSweet sorghum is a domesticated grass containing a sugar-rich juice that can be readily utilized for ethanol production. Most of the sugar is stored inside the cells of the stalk tissue and can be difficult to release, a necessary step before conventional fermentation. While this crop holds much promise as an arid land sugar source for biofuel production, a number of challenges must be overcome. One lies in the inherent labile nature of the sugars in the stalks leading to a short usable storage time. Also, collection of sugars from the sweet sorghum stalks is usually accomplished by mechanical squeezing, but generally does not collect all of the available sugars.ResultsIn this paper, we present two methods that address these challenges for utilization of sweet sorghum for biofuel production. The first method demonstrates a means to store sweet sorghum stalks in the field under semi-arid conditions. The second provides an efficient water extraction method that can collect as much of the available sugar as feasible. Operating parameters investigated include temperature, stalk size, and solid–liquid ratio that impact both the rate of sugar release and the maximal amount recovered with a goal of low water use. The most desirable conditions include 30°C, 0.6 ratio of solid to liquid (w/w), which collects 90 % of the available sugar. Variations in extraction methods did not alter the efficiency of the eventual ethanol fermentation.ConclusionsThe water extraction method has the potential to be used for sugar extraction from both fresh sweet sorghum stalks and dried ones. When combined with current sugar extraction methods, the overall ethanol production efficiency would increase compared to current field practices.

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ADDITIONAL INDEX WORDS. freeze and frost damage, plant cold protection, radiation shield, biodegradable aqueous foam, and mulching. SUMMARY.Aqueous foam was developed to serve as a barrier to conductive, convective, and radiative heat transfer. Through the use of a bulking agent, the physical properties of gelatin-based foam were more stable, adhesive, biodegradable, and long lasting. The phytotoxicity, possible environmental hazard and removal of the foam were also considered. Resistance to freezing-thawing, heating-evaporation, and wind were evaluated. Studies to determine the foam's long-term stability under field weather conditions were completed. The handling and performance characteristics of the foam necessary for development of this application were determined. Factors that affect the physical properties and the utilization of the foam were quantified. These included the proportions of the foam components, the mixing temperature of the prefoam solution, the application temperature, and the rate of foam generation. The newly developed foam might be ideal for freeze and frost protection in agriculture.

The work of Harkins' and Smith2 first put the mechanism and kinetics of emulsion polymerization on a firm basis. They showed that the equation (where R, is t,he rate of polymerization in mole/liter sec., k , is the propagation constant in liter/mole sec., N is t,he number of particles per liter HzO, No is Avogndro's number and [MI is the monomer concentration in moles/liter in the monomerpolymer particles) agreed well with the observed rates of styrene polymerization for latices with particles less than 0.1 p in diameter. This equation can be derived by assuming initiation in the aqueous phase, the entry of single radicals into the monomer-polymer particle, no transfer of radicals out of the particle, and very rapid termination as soon as a radical enters a particle already containing a polymerizing radical.The last assumption can become invalid for two reasons: the particle may grow to a volume sufficient to allow two radicals to grow simultaneously for an appreciable time, or the termination constant k , could be so low as to prevent rapid termination, even in small particles. The first case, the volume effect, was discussed by Haward3 and recently by Roe and Brass4 and by VanderhofP and co-workers. That k, can decrease during the course of the polymerization was proposed by Norrish and Smith6 and by Trommsdorff7 and is sometimes known as the Trommsdorff or "gel" effect. Gerrens* has shown that the emulsion polymerization of styrene shows a weak gel effect at about 70% conversion and that several radicals per particle are polymerizing simultaneously. Since methyl methacrylate is subject to a strong gel effect in bulk polymerization, we have examined the kinetics of the emulsion polymerization of this monomer and compared them with the theories developed for styrene. EXPERIMENTAL

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The vapor phase bromination1 of a number of simple alkyl halides was carried out in a specially designed apparatus (Fig. 1). With the low-boiling alkyl halides, the bromination was carried out at atmospheric pressure, and a twenty-to thirty-fold excess of the alkyl halide was always present in the reaction chamber. The reactions, with the alkyl halides of higher boiling point (above 90°), were carried out at reduced pressure, and under these conditions the ratio of alkyl halide to bromine was somewhat smaller.

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SynopsisNew procedures have been developed to study the mechanism and kinetics of the crosslinking of acrylic polyols with hexa (methoxymethyl) melamine. Both the rate of gel formation and alcohol release are found to be affected by the concentration and the nature of the catalyst and to be proportional to the hydrogen ion concentration. The rate of gel formation can be modeled by using the Miller and Macosko procedure with the input consisting of the polymer composition and the rate of release of reaction products. The correlation between calculated and experimentally determined quantity of gel formed is good when the reactions are slow, but becomes poor when gel formation is rapid, suggesting that the formation of large rings is favored by rapid reaction. The rate of gel formation shows much less variation among different polymer systems than does the rate of release of reaction products from the crosslinking reaction.