Nonmarket cobenefits and economic feasibility of on-farm biogas energy production

Standard analysis of the economic feasibility of on-farm biogas energy production tend to emphasize primarily on direct financial benefits to farmers, and abstracts from the nonmarket cobenefits associated with anaerobic digestion of livestock manure and other biomass feedstock. This shortcoming of the standard feasibility analysis raises a fundamental question: How is the economic feasibility of on-farm anaerobic biogas energy production affected by the associated nonpecuniary cobenefits? Incorporating key nonmarket cobenefits from biogas energy production extends the standard economic feasibility analysis, and provides important insights. When nonmarket cobenefits were excluded, on-farm biogas energy production was generally not financially feasible for the dairy and swine farm size ranges studied (except for 600- and 800-sow farms). Overall, results of the financial feasibility analysis did not change compared to a base scenario (without nonmarket cobenefits) when an estimated annual total nonmarket cobenefits of CND$5000 was incorporated into the analysis, for both dairy and swine farms. Biogas energy production was generally financially viable for small-size dairy (i.e., 50-cow) and swine (i.e., 200-sow) farms when the nonmarket cobenefits were valued at CND$15,000 (or higher). Improvements in financial feasibility were more dramatic for dairy than for swine farms.     

Heat transfer and pressure drop correlations for laminar flow in an in-line and staggered array of circular cylinders

Enhanced heat transfer surfaces based on cylindrically shaped pin fins with wire diameters in the range of 100?µm were analyzed. The design is based on a high pin length to diameter ratio in the range of 20–100. Correlations for thermal and fluid dynamic characteristics of these fine wire structures are not available in literature. An in-line and staggered arrangement of pins were simulated for a variety of operational and geometrical conditions with a two-dimensional computational thermal and fluid dynamics model. Correlations for Nusselt number and friction factor with respect to Reynolds number and geometry were derived thereby. Reynolds numbers based on the wire diameter are in the range of 3–60. The correlations for the Nusselt number and friction factor can predict 93% and 97% of the simulated data within ±10%.     

Eine kritische Analyse von Vernetzungsmaßen in sozialen Netzwerken

Social networks are currently gaining increasing impact in the light of the ongoing growth of web-based services like facebook.com. One major challenge for the economically successful implementation of selected management activities such as viral marketing is the identification of key persons with an outstanding structural position within the network. For this purpose, social network analysis provides a lot of measures for quantifying a member’s interconnectedness within social networks. In this context, our paper shows the state of the art with regard to centrality measures for social networks. Due to strongly differing results with respect to the quality of different centrality measures, this paper also aims at illustrating the tremendous importance of a reflected utilization of existing centrality measures. For this purpose, the paper analyzes five centrality measures commonly discussed in literature on the basis of three simple requirements for the behavior of centrality measures.     

Preservation of primer and probes on “ready-to-use” 96-well microtiter plates: A step forward towards enhancing throughput and harmonization of real-time PCR applications in food and feed control

Three different agents, trehalose (TRH), gelatine (GEL) and polyethylene glycol (PEG) were investigated regarding their capability to preserve oligonucleotides, such as primer and probes or double-stranded plasmid DNA, pre-coated in 96-wells microtiter plates. The evaluation of the retained efficiency of selected multi-copy and two single-copy PCR (polymerase chain reaction) systems revealed best-suited final concentrations in the preservation mix of 1.5% (w/v) for PEG, 0.17% (w/v) for GEL and 0.07% (w/v) - 20/1 (TRH/nucleic acid w/w) - for TRH, respectively. Under these conditions PCR efficiencies did not deviate significantly from non-coated, freshly pipetted control reactions even after three months of storage at room temperature or under thermal stress at constantly 50 °C simulating an ageing effect. Among the three reagents TRH showed best performance since not only the most labile component - the fluorescent probe - is protected from degradation but also double-stranded plasmid DNA which can be used as reference material and in quantitative real-time PCR.     

RNA Aminoacylation Mediated by Sequential Action of Two Ribozymes and a Nonactivated Amino Acid

In the transition from the RNA world to the modern DNA/protein world, RNA‐catalyzed aminoacylation might have been a key step towards early translation. A number of ribozymes capable of aminoacylating their own 3′ termini have been developed by in vitro selection. However, all of those catalysts require a previously activated amino acid—typically an aminoacyl‐AMP—as substrate. Here we present two ribozymes connected by intermolecular base pairing and carrying out the two steps of aminoacylation: ribozyme 1 loads nonactivated phenylalanine onto its phosphorylated 5′ terminus, thereby forming a high‐energy mixed anhydride. Thereafter, a complex of ribozymes 1 and 2 is formed by intermolecular base pairing, and the “activated” phenylalanine is transferred from the 5′ terminus of ribozyme 1 to the 3′ terminus of ribozyme 2. This kind of simple RNA aminoacylase complex was engineered from previously selected ribozymes possessing the two required activities. RNA aminoacylation with a nonactivated amino acid as described here is advantageous to RNA world scenarios because initial amino acid activation by an additional reagent (in most cases, ATP) and an additional ribozyme would not be necessary.     

Analytical prediction of roll coating with counter-rotating deformable rolls

Roll coating is a common technique for applying thin coating films on continuous substrates, e.g., papers and foils. Key advantages are the comparatively simple technology and the possibility of coating thin films using highly viscous fluids. Since roll coating is a self-metered process, the prediction of film thicknesses is of fundamental interest for industrial process control. In the present work, a new analytical approach for the prediction of the film thickness in roll coating with deformable rolls and negative gaps is developed. This method is based on the fluid dynamic theory of lubrication approximation. The film thickness is calculated depending on the geometry of the rolls (including the elasticity of the rubber), the fluid properties of the applied film and the roll velocities. This is gained by using boundary conditions for pressure and—in contrast to former literature—for force. The quality of the predicted results is validated with experimental data from literature. The comparison shows good agreement and thus the derived analytical model offers new possibilities for predicting film thickness and understanding of the associated influence parameters.     

Use of Cascaded Option Trees in Chemical‐Engineering Process Development

Fast and efficient procedures are increasingly important in process development since the time frame between development and market entry is reduced. The evaluation of alternatives is time consuming, but especially important to assure the choice of the optimal process. A simple and fast method to speed up process development while considering numerous alternatives has been developed using option trees. The option trees allow for easy and comprehensible evaluation of alternatives. Here the method of cascaded option trees is illustrated for the development of a biocompatible separation process.