Species Composition Changes in Conservation Reserve Program (CRP) Grassland When Managed for Biomass Feedstock Production

Grasslands enrolled in the Conservation Reserve Program (CRP) serve as one of the potential national herbaceous resources for use as a dedicated bioenergy feedstock. The goal of this project was to assess the yield potential and suitability of CRP grassland as a bioenergy feedstock source across the USA in regions with significant CRP land resources. In addition to that goal, one major objective of this project was to assess vegetation composition changes that also occurred on these different CRP grasslands over time with different harvest and fertilization management strategies. Three levels of nitrogen fertilization (0, 56, and 112 kg ha^?1) and two harvest timings [peak standing crop (PSC) or end of growing season (EGS)] were evaluated for effects on biomass production and resulting species composition changes. Three sites in regions containing concentrated tracts of CRP grassland and representing variable climatic parameters were analyzed for vegetation composition trends over the course of six growing seasons (2008–2013). Specifically, a mixture of warm-season perennial grasses was evaluated in Kansas (KS), while a cool-season mixture was evaluated in Missouri (MO). North Dakota (ND) contained a mixture of both warm- and cool-season grasses. At the MO and KS sites, nitrogen fertilization significantly altered the grass and legume composition over time by lowering the legume percentage in the stand. In KS and ND, the two sites with warm-season grasses, harvesting in mid-summer at PSC, greatly reduced warm-season grass composition over time in favor of annual cool-season grass invaders or perennial cool-season grasses. Any shift to less desirable or less productive species limits the ability of these lands to provide a sustainable or reliable feedstock for bioenergy production.     

Optimization and Evaluation of Sugars and Chemicals Production from Green Macro-algae <Emphasis Type="Italic">Enteromorpha intestinalis</Emphasis>

This work investigated the optimization of sugar and chemical formation from marine macro-green-alga Enteromorpha intestinalis by hydrothermal reaction and a statistical methodology. By this approach, the highest sugar and chemical yields were predicted as follows: glucose 10.42 %, xylose-mannose-galactose (XMG) 18.08 %, total reducing sugar (TRS) 28.61 % (reaction temperature 156 °C, catalyst amount 1.3 %, reaction time 11.4 min), levulinic acid 4.00 % (175.0 °C, 3.7 %, 35 min), 5-hydroxymethylfurfural 1.71 % (186.0 °C, 1.1 %, 37.9 min), and furfural 2.03 % (183.1 °C, 2.2 %, 10.7 min). In terms of the combined severity factor (CSF), the glucose, XMG, and TRS production decreased linearly with increasing CSF and to a high correlation. This application of a marine green-alga shows a high potential for production of fermentable sugars and chemicals suitable for biorefinement processes.     

Patient admission planning using Approximate Dynamic Programming

Tactical planning in hospitals involves elective patient admission planning and the allocation of hospital resource capacities. We propose a method to develop a tactical resource allocation and patient admission plan that takes stochastic elements into consideration, thereby providing robust plans. Our method is developed in an Approximate Dynamic Programming (ADP) framework and copes with multiple resources, multiple time periods and multiple patient groups with uncertain treatment paths and an uncertain number of arrivals in each time period. As such, the method enables integrated decision making for a network of hospital departments and resources. Computational results indicate that the ADP approach provides an accurate approximation of the value functions, and that it is suitable for large problem instances at hospitals, in which the ADP approach performs significantly better than two other heuristic approaches. Our ADP algorithm is generic, as various cost functions and basis functions can be used in various hospital settings.     

Production of 2,3-Butanediol from Sucrose by a <Emphasis Type="Italic">Klebsiella</Emphasis> Species

Chemical 2,3-butanediol is an important platform compound possessing diverse industrial applications. So far, it is mainly produced by using petrochemical feedstock which is associated with high cost and adverse environmental impacts. Hence, finding alternative routes (e.g., via fermentation using renewable carbon sources) to produce 2,3-butanediol are urgently needed. In this study, we report a wild-type Klebsiella sp. strain XRM21, which is capable of producing 2,3-butanediol from a wide variety of carbon sources including glucose, sucrose, xylose, and glycerol. Among them, fermentation of sucrose leads to the highest production of 2,3-butanediol. To maximize the production of 2,3-butanediol, fermentation conditions were first optimized for strain XMR21 by using response surface methodology (RSM) in batch reactors. Subsequently, a fed-batch fermentation strategy was designed based on the optimized parameters, where 91.2 g/L of 2,3-butanediol could be produced from substrate sucrose dosing in 100 g/L for three times. Moreover, random mutagenesis of stain XMR21 resulted in a highly productive mutant strain, capable of producing 119.4 and 22.5 g/L of 2,3-butanediol and ethanol under optimized fed-batch fermentation process within 65 h with a total productivity of 2.18 g/L/h, which is comparable to the reported highest 2,3-butanediol concentration produced by previous strains. This study provides a potential strategy to produce industrially important 2,3-butanediol from low-cost sucrose.     

Assessing the Performance of Bacterial Cellulases: the Use of <Emphasis Type="Italic">Bacillus</Emphasis> and <Emphasis Type="Italic">Paenibacillus</Emphasis> Strains as Enzyme Sources for Lignocellulose Saccharification

Plant biomass offers a renewable and environmentally favorable source of sugars that can be converted to different chemicals, second-generation ethanol, and other liquid fuels. Cellulose makes up approximately 45 % of the dry weight of lignocellulosic biomass. Prior to the enzymatic hydrolysis of cellulose, lignin and hemicellulose must be structurally altered or removed, at least in part, by chemical and/or physical pretreatments. However, the high cost and low efficiency of the enzymatic hydrolysis prevent the process from being economically competitive. For this reason, it is necessary to find enzymes suitable for this type of process, with higher specific activities and greater efficiency. Members of the Bacillus and Paenibacillus genera have been traditionally used for the production of many enzymes for industrial applications. Cellulases produced by both genera have shown activity on soluble and crystalline cellulose and high thermostability and/or activity over a wide pH spectrum. In this review, the most recent information about the characterization of cellulolytic enzymes obtained from new strains of the Bacillus and Paenibacillus genera are reviewed. We focused on the variety of isoenzymes produced by these cellulolytic strains, their optimal production and reaction conditions, and their kinetic parameters and biotechnological potential.     

A note on the selection of priority rules in software packages for project management

Various software packages for project management include a procedure for resource-constrained scheduling. In several packages, the user can influence this procedure by selecting a priority rule. However, the resource-allocation methods that are implemented in the procedures are proprietary information; therefore, the question of how the priority-rule selection impacts the performance of the procedures arises. We experimentally evaluate the resource-allocation methods of eight recent software packages using the 600 instances of the PSPLIB J120 test set. The results of our analysis indicate that applying the default rule tends to outperform a randomly selected rule, whereas applying two randomly selected rules tends to outperform the default rule. Applying a small set of more than two rules further improves the project durations considerably. However, a large number of rules must be applied to obtain the best possible project durations.     

How Does Hemicelluloses Removal Alter Plant Cell Wall Nanoscale Architecture and Correlate with Enzymatic Digestibility?

Thorough understanding of how hemicelluloses removal influences cell wall nanoscale architecture and cellulose digestion is of crucial importance for enabling low-cost industrial conversion of lignocellulosic biomass to renewable biofuels. In this work, delignified poplar cell walls, after various degrees of hemicelluloses removal, were characterized by Fourier transform infrared imaging spectroscopy and atomic force microscopy to evaluate enhancement in cell wall digestibility. There was a gradual decrease in hemicelluloses content with dilute alkali treatment, which resulted in alterations in the nanoscale architecture and crystallinity of cell walls. Removal of hemicelluloses did not disrupt the integrity of microfibrils but resulted in exposure of microfibrils and a decrease in the diameter of microfibrils. X-ray analysis indicated that the increase in crystallinity beyond natural variations in the crystallinity of cellulose was mainly attributable to removal of hemicelluloses. In conclusion, alterations in the architecture and crystallinity of cell walls facilitated enzymatic digestion of delignified poplar, enhancing cellulose conversion from 68.24 to 75.16 %.     

Production of Cold-Flow Quality Biodiesel from High-Acidity On-Edible Oils—Esterification and Transesterification of Macauba (<Emphasis Type="Italic">Acrocomia aculeata</Emphasis>) Oil Using Various Alcohols

Biodiesel is an alternative fuel that has been used for partial or total substitution of diesel to reduce its environmental impacts. Prior studies on this topic have focused on the quest for better synthesis process, new catalysts and low-cost non-food and raw materials to improve the economic and sustainable production as well as product quality. In this study, acidic oil from macauba, a palm tree native to South America that has no food uses, was converted into biodiesel. The esterification and transesterification reactions were performed with methanol, ethanol and isobutanol with the goal of improving the cold properties of the biodiesel. The isobutyl ester exhibited the lowest freezing point temperature but underperformed outside of international specifications for kinematic viscosity; it also exhibited a low ester content. The methyl and ethyl esters were within the specifications of the international standards for ester content, density, kinematic viscosity and sulphur content. The ethyl ester produced from macauba oil displayed better properties in cold conditions than methyl and isobutyl esters studied here, with a cold filter plugging point of 0 °C. Its onset crystallisation temperature was reduced from ?5.96 to ?13.41 °C when subjected to fractional crystallisation. The ethyl ester exhibited the best lubricity value among the other esters studied.     

Establishment and Early Growth of Willow at Different Levels of Weed Competition and Nitrogen Fertilization

To evaluate the effects of weed competition and nitrogen fertilization on the early growth performance of willow, cuttings of the clone Tora (Salix schwerinii x S. viminalis) were planted in buckets together with model weeds (spring barley or white mustard) sown 15, 26, and 30 days after willow planting. The buckets were fertilized with 30 or 90 kg N ha^?1. Willow with weeds sown after 15 days produced less biomass and smaller leaf area and had a lower maximum shoot height compared to willow planted without weeds and willow with weeds sown after 26 or 30 days. Fertilization with 90 kg N ha^?1 gave higher willow biomass production in willow with weeds sown after 26 or 30 days. Type of model weed had no effect on willow performance. Weed biomass and maximum shoot height were higher in weeds planted without willows compared to the willow-weed mixtures. A high nitrogen level gave more weed biomass when planted without willows and in the willow-weed mixture with weeds sown after 15 days. We conclude that for the given high density of willow, competition from weeds emerging soon after willow planting had strong effect on early production. Furthermore, if there is a risk of weed infestation, fertilization should be delayed.