Distributed Primary Frequency Control through Multi-Terminal HVDC Transmission Systems

This paper presents a decentralized controller for sharing primary AC frequency control reserves through a multi-terminal HVDC grid. By using Lyapunov arguments, the proposed controller is shown to stabilize the equilibrium of the closed-loop system consisting of the interconnected AC and HVDC grids, given any positive controller gains. The static control errors resulting from the proportional controller are quantified and bounded by analyzing the equilibrium of the closed-loop system. The proposed controller is applied to a test grid consisting of three asynchronous AC areas interconnected by an HVDC grid, and its effectiveness is validated through simulation

Recent Advances in Starch-Based Blends and Composites for Bioplastics Applications

Environmental pollution by synthetic polymers is a global problem and investigating substitutes for synthetic polymers is a major research area. Starch can be used in formulating bioplastic materials, mainly as blends or composites with other polymers. The major drawbacks of using starch in such applications are water sensitivity and poor mechanical properties. Attempts have been made to improve the mechanical properties of starch-based blends and composites, by e.g., starch modification or plasticization, matrix reinforcement, and polymer blending. Polymer blending can bring synergetic benefits to blends and composites, but necessary precautions must be taken to ensure the compatibility of hydrophobic polymers and hydrophilic starch. Genetic engineering offers new possibilities to modify starch inplanta in a manner favorable for bioplastics applications, while the incorporation of antibacterial and/or antioxidant agents into starch-based food packaging materials brings additional advantages. In conclusion, starch is a promising material for bioplastic production, with great potential for further improvements. This review summarizes the recent advances in starch-based blends and composites and highlights the potential strategies for overcoming the major drawbacks of using starch in bioplastics applications

Distributed Secondary Frequency Control through MTDC Transmission Systems

In this paper, we present distributed controllers for sharing primary and secondary frequency control reserves for asynchronous AC transmission systems, which are connected through a multi-terminal HVDC grid. By using Lyapunov arguments, the equilibria of the closed-loop system are shown to be globally asymptotically stable. We quantify the static errors of the voltages and frequencies, and give upper bounds for these errors. It is also shown that the controllers have the property of power sharing, i.e., primary and secondary frequency control reserves are shared fairly amongst the AC systems. The proposed controllers are applied to a high-order dynamic model of of a power system consisting of asynchronous AC grids connected through a six-terminal HVDC grid.Comment: arXiv admin note: text overlap with arXiv:1409.801

Evolution of glutamate dehydrogenase genes: evidence for lateral gene transfer within and between prokaryotes and eukaryotes

BACKGROUND: Lateral gene transfer can introduce genes with novel functions into genomes or replace genes with functionally similar orthologs or paralogs. Here we present a study of the occurrence of the latter gene replacement phenomenon in the four gene families encoding different classes of glutamate dehydrogenase (GDH), to evaluate and compare the patterns and rates of lateral gene transfer (LGT) in prokaryotes and eukaryotes. RESULTS: We extend the taxon sampling of gdh genes with nine new eukaryotic sequences and examine the phylogenetic distribution pattern of the various GDH classes in combination with maximum likelihood phylogenetic analyses. The distribution pattern analyses indicate that LGT has played a significant role in the evolution of the four gdh gene families. Indeed, a number of gene transfer events are identified by phylogenetic analyses, including numerous prokaryotic intra-domain transfers, some prokaryotic inter-domain transfers and several inter-domain transfers between prokaryotes and microbial eukaryotes (protists). CONCLUSION: LGT has apparently affected eukaryotes and prokaryotes to a similar extent within the gdh gene families. In the absence of indications that the evolution of the gdh gene families is radically different from other families, these results suggest that gene transfer might be an important evolutionary mechanism in microbial eukaryote genome evolution

CLEANING HIGH-SPEED MARINE SEPARATORS WITH AN ENVIRONMENTALLY-FRIENDLY CIP AGENT

The present contribution is devoted to the cleaning of high-speed marine separators employing the environmentally-friendly Cleaning In Place (CIP) agent Alpacon Multi Cip Super. For this particular study an Alfa Laval lube oil separator of type S831 on board the ship MS Isabella was dismantled prior to its first CIP treatment since installation and a few of the sludge-coated insert discs were taken as samples for laboratory experiments. Following assembly, the separator was cleaned according to a standard CIP protocol. Back in the laboratory, experiments mimicking the field CIP conditions verified the excellent cleaning results observed by visual inspection out on the ship after the CIP treatment

Using visual lateralization to model learning and memory in zebrafish larvae.

Impaired learning and memory are common symptoms of neurodegenerative and neuropsychiatric diseases. Present, there are several behavioural test employed to assess cognitive functions in animal models, including the frequently used novel object recognition (NOR) test. However, although atypical functional brain lateralization has been associated with neuropsychiatric conditions, spanning from schizophrenia to autism, few animal models are available to study this phenomenon in learning and memory deficits. Here we present a visual lateralization NOR model (VLNOR) in zebrafish larvae as an assay that combines brain lateralization and NOR. In zebrafish larvae, learning and memory are generally assessed by habituation, sensitization, or conditioning paradigms, which are all representatives of nondeclarative memory. The VLNOR is the first model for zebrafish larvae that studies a memory similar to the declarative memory described for mammals. We demonstrate that VLNOR can be used to study memory formation, storage, and recall of novel objects, both short and long term, in 10-day-old zebrafish. Furthermore we show that the VLNOR model can be used to study chemical modulation of memory formation and maintenance using dizocilpine (MK-801), a frequently used non-competitive antagonist of the NMDA receptor, used to test putative antipsychotics in animal models

Några för Sverige nya pyrenomyceter

Additions to the most recently published checklist of non-lichenized ascomycetes in Sweden (Eriksson 2014) are made and commented. Findings of the following species of ‘pyrenomycetes’ in the Ascomycota classes Sordariomycetes and Dothideomycetes are reported: Anthostomella phaeosticta, Barrmaelia moravica, Fracchinea broomeana, Helminthosporium oligosporum, Helminthosporium tiliae, Jattaea ceanothina, Leptomassaria simplex, Lopadostoma dryophilum, Lophiostoma fusisporum, Massaria platanoidea, Massaria vomitoria, Plagiostoma aesculi, Stylonectria wegeliniana, and Vialaea insculpta

A water-soluble fraction from a by-product of wheat increases the formation of propionic acid in rats compared with diets based on other by-product fractions and oligofructose

Background: Dietary fibre is fermented by the colonic microbiota to carboxylic acids (CA), with potential health effects associated in particular with butyric and propionic acid. Objective: To investigate the formation of CA in the hindgut of healthy rats fed dietary fibre from different fractions of wheat shorts, a by-product of the milling of wheat. Design: Rats were fed dietary fibre (80 g/kg feed per day for 7 days) from wheat shorts and fractions thereof (ethanol-soluble, water-soluble and insoluble fractions), oligofructose (OF) diet and a mixture of oligofructose and raffinose (OR) diet. Results: The water-soluble fraction, with a high content of arabinoxylan (AX), increased the formation of propionic acid in the hindgut and lowered the ratio of acetic to propionic acid in the portal blood of rats. High levels and proportions of butyric acid were seen in rats fed the OR diet. The pattern of CA resulting from the ethanol-soluble diet, mainly composed of fructan and raffinose, was more similar to that of the OF diet than the OR diet. Conclusions: The high formation of propionic acid with the water-soluble fraction may be attributed to the high AX content. The results also indicate that the wheat fructans produced more propionic acid and less butyric acid than oligofructose. It may furthermore be speculated that the increased formation of butyrate with the OR diet was due to synergistic effects of the components in this diet

Side Streams of Broccoli Leaves: A Climate Smart and Healthy Food Ingredient

Human consumption of fruits and vegetables are generally below recommended levels. Waste from the production, e.g., of un-used parts such as broccoli leaves and stem when producing broccoli florets for food, is a sustainability issue. In this study, broccoli leaves were analyzed for the content of various dietary fibre and phenolics, applying the Uppsala method and HPLC analyses, respectively. The results showed that broccoli leaves had comparable levels of dietary fibre (26%-32% of dry weight (DW)) and phenolic compounds (6.3-15.2 mg/g DW) to many other food and vegetables considered valuable in the human diet from a health perspective. A significant positive correlation was found among soluble dietary fibre and phenolic acids indicating possible bindings between these components. Seasonal variations affected mainly the content of conjugated phenolics, and the content of insoluble dietary fibre. This study verified the importance of the use of broccoli production side streams (leaves) as they may contribute with health promoting components to the human diet and also socio-economic and environmental benefits to the bioeconomic development in the society