281 research outputs found
The effects of geometry and operational conditions on gas holdup, liquid circulation and mass transfer in an airlift reactor
Исследование системы РЗЭ (OH)3−NH4Cl при нагревании
The temporal evolution of neon pinch plasmas, generated in a 2kJ plasma focus device, has been investigated by x-ray spectroscopic methods for two sets of device parameters. These two sets lead to characteristic differences of the K-shell emission. Stationary models are shown to fail to explain the experimental observations even qualitatively. Transient spectra analysis shows that the characteristic differences observed can be referred to different transient modes of plasma dynamics. The spectra analysis includes beside resonance lines also dielectronic satellites and recombination continua. The results concerning the development of the plasma parameters achieved by the spectra modeling are supported by independent measurements of the time resolved K-shell emission and by optical streak images of the pinch plasma dynamics, which confirms the reliability of the transient spectroscopic analysis presented
ORGANIC AGRICULTURE AND FOOD PRODUCTION UNDER EU HIGH QUALITY SCHEMES: EVOLUTION AND DYNAMICS IN ROMANIA AND OTHER MEMBER STATES
In Romania, the area under organic crops multiplied 13 times between 2000-2016. Presently, the domestic demand is higher than the domestic supply and imports are needed, especially of processed products; at the same time, Romania is exporting organic products to Western countries. The EU high quality schemes include other categories of manufactured food products which are specially registered in the EU-DOOR database; Romania is present with four registered products only. The present paper is analyzing the evolution and dynamics of the organic production and of the food products included in the national and EU high quality schemes in Romania as compared to other EU countries. The upward trend is expected to continue, and the financial support foreseen for the period 2014-2020 will further encourage the development of this sector. Â
Bioremediation of Cr(VI) polluted wastewaters by sorption on heat inactivated Saccharomyces cerevisiae biomass
The potential of heat inactivated Saccharomyces cerevisiae in the bioremoval and reduction of
Cr (VI) ions from wastewaters was evaluated in terms of metal uptake in time and at equilibrium, and
biosorption efficiency, by varying pH, biosorbent doses, contact time and temperature, in batch mode. During the sorption process, the heat inactivated biomass of the yeast Saccharomyces cerevisiae is capable of reducing Cr(VI) to Cr(III). Different kinetic models based on adsorption and reduction are used to represent the kinetic data of Cr(VI) bioremoval by S. cerevisiae, in explaining the biosorption mechanism of heavy metals and potential rate-controlling steps, in the perspective of full-scale process design. The results indicated some potential differences in the Cr(VI) removal mechanism at different experimental conditions. FTIR and SEM analysis were performed as well as to elucidate the mechanism of metal bioremoval by S. cerevisiae. FTIR spectra indicate that heavy metal bioremoval process doesn’t imply in this case the formation of stable covalent bonds, but it is predominantly based on chemical interactions, ion-exchange type. The SEM micrographs of Cr-loaded yeast, indicates that the surface morphology doesn’t change much after chromium ions were uptaken. This leads to the conclusion that Cr(VI) reduction occurs at the interface of the adsorbent.This paper was elaborated with the support of BRAIN project Doctoral scholarships as an investment in intelligence - ID 6681, financed by the European Social Found and Romanian Government and with the support of a grant of the Romanian National Authority for Scientific Research, CNCS - UEFISCDI, project number PN-II-ID-PCE-2011-3-0559", Contract 265/2011
Integrated supply chain design for commodity chemicals production via woody biomass fast pyrolysis and upgrading
This study investigates the optimal supply chain design for commodity chemicals (BTX, etc.) production via woody biomass fast pyrolysis and hydroprocessing pathway. The locations and capacities of distributed preprocessing hubs and integrated biorefinery facilities are optimized with a mixed integer linear programming model. In this integrated supply chain system, decisions on the biomass chipping methods (roadside chipping vs. facility chipping) are also explored. The economic objective of the supply chain model is to maximize the profit for a 20-year chemicals production system. In addition to the economic objective, the model also incorporates an environmental objective of minimizing life cycle greenhouse gas emissions, analyzing the trade-off between the economic and environmental considerations. The capital cost, operating cost, and revenues for the biorefinery facilities are based on techno-economic analysis, and the proposed approach is illustrated through a case study of Minnesota, with Minneapolis-St. Paul serving as the chemicals distribution hub
Hydrodynamic Considerations in an External Loop Airlift Reactor with a Modified Downcomer
OptFlux: an open-source software platform for in silico metabolic engineering
<p>Abstract</p> <p>Background</p> <p>Over the last few years a number of methods have been proposed for the phenotype simulation of microorganisms under different environmental and genetic conditions. These have been used as the basis to support the discovery of successful genetic modifications of the microbial metabolism to address industrial goals. However, the use of these methods has been restricted to bioinformaticians or other expert researchers. The main aim of this work is, therefore, to provide a user-friendly computational tool for Metabolic Engineering applications.</p> <p>Results</p> <p><it>OptFlux </it>is an open-source and modular software aimed at being the reference computational application in the field. It is the first tool to incorporate strain optimization tasks, i.e., the identification of Metabolic Engineering targets, using Evolutionary Algorithms/Simulated Annealing metaheuristics or the previously proposed OptKnock algorithm. It also allows the use of stoichiometric metabolic models for (i) phenotype simulation of both wild-type and mutant organisms, using the methods of Flux Balance Analysis, Minimization of Metabolic Adjustment or Regulatory on/off Minimization of Metabolic flux changes, (ii) Metabolic Flux Analysis, computing the admissible flux space given a set of measured fluxes, and (iii) pathway analysis through the calculation of Elementary Flux Modes.</p> <p><it>OptFlux </it>also contemplates several methods for model simplification and other pre-processing operations aimed at reducing the search space for optimization algorithms.</p> <p>The software supports importing/exporting to several flat file formats and it is compatible with the SBML standard. <it>OptFlux </it>has a visualization module that allows the analysis of the model structure that is compatible with the layout information of <it>Cell Designer</it>, allowing the superimposition of simulation results with the model graph.</p> <p>Conclusions</p> <p>The <it>OptFlux </it>software is freely available, together with documentation and other resources, thus bridging the gap from research in strain optimization algorithms and the final users. It is a valuable platform for researchers in the field that have available a number of useful tools. Its open-source nature invites contributions by all those interested in making their methods available for the community.</p> <p>Given its plug-in based architecture it can be extended with new functionalities. Currently, several plug-ins are being developed, including network topology analysis tools and the integration with Boolean network based regulatory models.</p
In Vitro Study of the Effects of Angiostrongylus cantonensis Larvae Extracts on Apoptosis and Dysfunction in the Blood-Brain Barrier (BBB)
It has been hypothesized that blood-brain barrier (BBB) dysfunction in Angiostrongylus cantonensis infection might be due to the apoptosis of the hosts' BBB cells. Here, we evaluated this hypothesis through several methods, all based on an in vitro mouse BBB model consisting of primary culture brain microvascular endothelial cells (BMECs) and brain astrocytic cells (BACs). In the present study, a four-hour percolation and HRP permeability experiment showed that A. cantonensis larvae extracts can increase the permeability of the BBB. Apoptosis among BMECs and BACs after exposure to larvae extracts was monitored by TUNEL and annexin-V-FITC/PI double staining. A. cantonensis larvae extracts were found to induce apoptosis in both BMECs and BACs. For this reason, we concluded that the induction of apoptosis might participate in the BBB dysfunction observed during angiostrongyliasis. Improved fundamental understanding of how A. cantonensis induces apoptosis may lead to new approaches to the treatment or prevention of this parasitic disease
The significance of peroxisomes in secondary metabolite biosynthesis in filamentous fungi
Peroxisomes are ubiquitous organelles characterized by a protein-rich matrix surrounded by a single membrane. In filamentous fungi, peroxisomes are crucial for the primary metabolism of several unusual carbon sources used for growth (e.g. fatty acids), but increasing evidence is presented that emphasize the crucial role of these organelles in the formation of a variety of secondary metabolites. In filamentous fungi, peroxisomes also play a role in development and differentiation whereas specialized peroxisomes, the Woronin bodies, play a structural role in plugging septal pores. The biogenesis of peroxisomes in filamentous fungi involves the function of conserved PEX genes, as well as genes that are unique for these organisms. Peroxisomes are also subject to autophagic degradation, a process that involves ATG genes. The interplay between organelle biogenesis and degradation may serve a quality control function, thereby allowing a continuous rejuvenation of the organelle population in the cells
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