Modulated differential scanning calorimetry has been used to quantify the glass transitions of small adsorbed amounts of poly(methyl methacrylate) (PMMA) on silica. While a relatively narrow, single glass transition was found for bulk PMMA, broader two-component transitions were found for the adsorbed polymer. A two-state model based on loosely bound polymer (glass transition similar to bulk) and more tightly bound polymer (glass transition centered around 156 degrees C) was used to interpret the thermograms. On the basis of this model, the amount of tightly bound polymer was found to be approximately 1.3 mg/m2, corresponding to a 1.1 nm thick layer. The change in heat capacity for the tightly bound polymer at the glass transition temperature was estimated to be about 16% of that of the bulk polymer.
Biofuels are anticipated to enable a shift from fossil fuels for renewable transportation and manufacturing fuels, with biohydrogen considered attractive since it could offer the largest reduction of global carbon budgets. Currently, lignocellulosic biohydrogen production remains inefficient with pretreatments that are heavily fossil fuel-dependent. However, bacteria using alkali-treated biomass could streamline biofuel production while reducing costs and fossil fuel needs. An alkaliphilic bacterium, Halanaerobium hydrogeniformans, is described that is capable of biohydrogen production at levels rivaling neutrophilic strains, but at pH 11 and hypersaline conditions. H. hydrogeniformans ferments a variety of 5- and 6-carbon sugars derived from hemicellulose and cellulose including cellobiose, and forms the end products hydrogen, acetate, and formate. Further, it can also produce biohydrogen from switchgrass and straw pretreated at temperatures far lower than any previously reported and in solutions compatible with growth. Hence, this bacterium can potentially increase the efficiency and efficacy of biohydrogen production from renewable biomass resources.
SummaryBiomass can be converted to sugars by hydrolysis with enzymes or mineral acids. These sugars can be converted into a number of chemical intermediates in biological reactors. Biological reactions are generally slow and selection of the most efficient reactor is important in these applications. Immobilized-cell reactors allow high cell densities and high throughput by attaching the microorganisms to a fixed support. This paper examines the rate of production of ethanol from glucose by Saccharomyces cerevisiae in a packed column. These rates are compared with those for the same reaction in a stirred reactor.
SummaryLaboratory studies at the University of Missouri-Rolla have demonstrated the feasibility of producing methane by anaerobic digestion of various crop materials, such as grasses and corn stalks. These studies indicate that up to 6.0 P methane are producedllb crop material destroyed. Preliminary design and economic studies of a large methane plant show that the reactors represent the largest cost item and that efforts should be concentrated on defining reaction kinetics and reactor design. A process to produce 50 M f3 methaneiday is described, and the preliminary design and economics are analyzed.
Polymer Bound Explosives (PBXs) and Class 1.1 Military Propellants have been reformulated for use in the mining industry. There is a minimal waste stream. The explosives are sensitive to initiation by a #8 cap. Impact sensitivities have routinely passed 5 kg meter stimuli, initiation by 50,000 V AC and the BAM friction protocols at 1000 rpm under a 1 1 kg load for 10 seconds. The explosives were packed into sticks, slurried or used as pourable mixes. VoDs of 2.4 to 6.2 k d s were realized with p = 0.9 -1.35 t/m3. The explosives have powers comparable to a range of dynamites. The Beaver Code based upon Lotus 1.2.3 -gTM was developed to predict explosive properties.Des explosifs de type PBX et des propergols militaires de classe 1 .I ont ete reformules pour utilisation dans I'industrie miniere. II existe un courant de rejet minimal. Les explosifs sont sensibles au declenchement par un detonateur #8. Les sensibilites a I'impact depassent des stimuli de 5 kg.m, un declenchement de 50,000 VAC et des protocoles de friction BAM a I000 tr/min pour une charge de 1 1 kg pendant I0 secondes. Les explosifs etaient emballes sous forme de bitonnets, conditionnes sous forme de boues ou utilises comme melanges a verser. Des VoDs de 2,4 a 6,2 km ont ete realises avec p = 0,9 -1,35 Urn3. Les explosifs ont des puissances comparables a celles des dynamites. On a elabore le Beaver Code a partir de Lotus 1 .2.3--5TM afin de predire les propriktes des explosifs.
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