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.     

Simultaneous Saccharification and Fermentation of Hydrothermal Pretreated Lignocellulosic Biomass: Evaluation of Process Performance Under Multiple Stress Conditions

Industrial lignocellulosic bioethanol processes are exposed to different environmental stresses (such as inhibitor compounds, high temperature, and high solid loadings). In this study, a systematic approach was followed where the liquid and solid fractions were mixed to evaluate the influence of varied solid loadings, and different percentages of liquor were used as liquid fraction to determine inhibitor effect. Ethanol production by simultaneous saccharification and fermentation (SSF) of hydrothermally pretreated Eucalyptus globulus wood (EGW) was studied under combined diverse stress operating conditions (30–38 °C, 60–80 g of liquor from hydrothermal treatment or autohydrolysis (containing inhibitor compounds)/100 g of liquid and liquid to solid ratio between 4 and 6.4 g liquid in SSF/g unwashed pretreated EGW) using an industrial Saccharomyces cerevisiae strain supplemented with low-cost byproducts derived from agro-food industry. Evaluation of these variables revealed that the combination of temperature and higher solid loadings was the most significant variable affecting final ethanol concentration and cellulose to ethanol conversion, whereas solid and autohydrolysis liquor loadings had the most significant impact on ethanol productivity. After optimization, an ethanol concentration of 54 g/L (corresponding to 85 % of conversion and 0.51 g/Lh of productivity at 96 h) was obtained at 37 °C using 60 % of autohydrolysis liquor and 16 % solid loading (liquid to solid ratio of 6.4 g/g). The selection of a suitable strain along with nutritional supplementation enabled to produce noticeable ethanol titers in quite restrictive SSF operating conditions, which can reduce operating cost and boost the economic feasibility of lignocellulose-to-ethanol processes.     

Impact of Different Lignin Fractions on Saccharification Efficiency in Diverse Species of the Bioenergy Crop Miscanthus

Lignin is a key factor limiting saccharification of lignocellulosic feedstocks. In this comparative study, various lignin methods—including acetyl bromide lignin (ABL), acid detergent lignin (ADL), Klason lignin (KL), and modified ADL and KL determination methods—were evaluated for their potential to assess saccharification efficiency. Six diverse accessions of the bioenergy crop miscanthus were used for this analysis, which included accessions of Miscanthus sinensis, Miscanthus sacchariflorus, and hybrid species. Accessions showed large variation in lignin content. Lignin estimates were different between methods, but (highly) correlated to each other (0.54?≤?r?≤?0.94). The strength of negative correlations to saccharification efficiency following either alkaline or dilute acid pretreatment differed between lignin estimates. The strongest and most consistent correlations (?0.48?≤?r?≤??0.85) were obtained with a modified Klason lignin method. This method is suitable for high throughput analysis and was the most effective in detecting differences in lignin content (p?<?0.001) between accessions.