Hoefdieren in de Manteling van Walcheren

In het natuurmonument de Manteling van Walcheren bevinden zich damherten en reeën. Beide soorten maken gebruik van buiten het natuurgebied gelegen landbouwgronden. In een aantal gevallen leidt dit tot klachten over schade en verkeersgevaarlijke situaties. Vanwege de verwachte invloed van met name de damherten op natuurwaarden binnen het reservaat, op de omringende landbouwgebieden en op de verkeersveiligheid, wordt voorgesteld om de populatie damherten getalsmatig te blijven beheren. Wat betreft de mogelijke invloed op de natuurwaarden in de Manteling bestaat er voor reeën geen aanleiding tot beheer. Voor de aspecten verkeersveiligheid en schade aan de landbouw ligt dit anders. Het rapport bevat een aantal suggesties om dit beheer te realiseren

Aanrijdingen met wilde hoefdieren in een boslandschap: de Veluwe

Sinds 1993 is er op de Veluwe sprake van een stijgende lijn in het aantal aanrijdingen met Reeën en Wilde zwijnen. In middels bedraagt het aantal aanrijdingen met hoefdieren meer dan 1000 per jaar. Het onderzoek naar de samenhang tussen de aanrijdingen per soort en bepaalde karakteristieken van het verkeer, de biotische en abiotische omgeving en de invloed van jacht leidt tot enkele aanbevelingen

Advies faunapassages oostvariant A-73; een expert view

Een expert view wordt gegeven op de vraag waar welke passagemogelijkheden moeten worden gecreëerd voor welke diersoorten in het oosttracé van de A73. Aangegeven wordt dat er ten minste acht robuustere kunstwerken dienen te worden gemaakt, waarvan één op het niveau van edelhert en de overige kleiner. Er wordt ingegaan op de minimumeisen waaraan de diverse constructies zullen moeten voldoen teneinde een optimaal toekomstig gebruik te bevorderen

Maatschappelijke randvoorwaarden

In dit hoofdstuk wordt achtereenvolgens de relatie tussen de aanwezigheid van edelherten enerzijds en veterinaire aspecten, de land- en bosbouwschade en de verkeersveiligheid anderzijds nader onderzoch

Validation of Ultrahigh Dependability for Software-Based Systems

Modern society depends on computers for a number of critical tasks in which failure can have very high costs. As a consequence, high levels of dependability (reliability, safety, etc.) are required from such computers, including their software. Whenever a quantitative approach to risk is adopted, these requirements must be stated in quantitative terms, and a rigorous demonstration of their being attained is necessary. For software used in the most critical roles, such demonstrations are not usually supplied. The fact is that the dependability requirements often lie near the limit of the current state of the art, or beyond, in terms not only of the ability to satisfy them, but also, and more often, of the ability to demonstrate that they are satisfied in the individual operational products (validation). We discuss reasons why such demonstrations cannot usually be provided with the means available: reliability growth models, testing with stable reliability, structural dependability modelling, as well as more informal arguments based on good engineering practice. We state some rigorous arguments about the limits of what can be validated with each of such means. Combining evidence from these different sources would seem to raise the levels that can be validated; yet this improvement is not such as to solve the problem. It appears that engineering practice must take into account the fact that no solution exists, at present, for the validation of ultra-high dependability in systems relying on complex software

Susceptibility testing of Candida albicans and Candida glabrata to Glycyrrhiza glabra L.

Medicinal plants and their botanical formulations have gained a pivotal attention among scientific researchers mainly due to its action as health promoters. Licorice (Glycyrrhiza glabra L.) constitutes a great example, with an increasingly evidenced antimicrobial potential. Opportunistic yeast infections constitute an alarming public health problem, highly exacerbated by the inefficacy of antifungal drugs and the increase of drug-resistant microorganisms, being Candida species one of the most common invaders. The present work aims to assess Candida glabrata and Candida albicans susceptibility to G. glabra methanol: water extract by using flow cytometry and transmission electron microscopy techniques. After 5 minutes, licorice extract (1.5 mg/mL) altered Candida membrane potential. Within an hour, it induced primary damages on Candida species cells, causing cell cytoplasm disorganization with high evidence of cell membrane invaginations, making cells turgid. Thus, based on the current findings, licorice extract seems to be a promising anti-Candida agent, without presenting any toxic potential at the effective concentrations used.The authors are grateful to Foundation for Science and Technology (FCT, Portugal) for N. Martins grant (SFRH/BD/87658/2012) and financial support to the research centre CIMO (strategic project PEst-OE/ AGR/UI0690/2014). This work was also supported by the Programa Operacional, Fatores de competitividade – COMPETE and by national funds through FCT – Fundação para a Ciência e a Tecnologia on the scope of the projects FCT PTDC/SAU-MIC/119069/2010, RECI/EBBEBI/0179/2012 and PEst-OE/EQB/LA0023/2013. The authors thank the Project “BioHealth – Biotechnology and Bioengineering approaches to improve health quality”, Ref. NORTE-07-0124-FEDER-000027, cofunded by the Programa Operacional Regional do Norte (ON.2–O Novo Norte), QREN, FEDER.info:eu-repo/semantics/publishedVersio

Fluidized bed roasting of micro-pelletized zinc concentrate : Part II-Particle entrainment and residence time

Zincor uses O2 enrichment (up to 26% O2 in the fluidizing air) to increase the processing rate of zinc concentrates in the fluidized bed roasters. The aim of this study is to determine whether O2 enrichment can be reduced by introducing micro-pelletized concentrate into the feed blend, while maintaining current roaster feed rates and calcine quality. It was found that, with a load of 20% micro-pellets introduced into the feed blend, that O2 enrichment could be reduced by 60%. It was determined that entrained particles spend on average between 0.46 hour and 2.44 hour in the roaster, compared to particles remaining between 3.93 hour and 4.00 hour in the bed overflow. This compares well with a radioactive tracer test performed by Spira. The required reaction time for micro-pellets was found to be less than the residence time inside a Zincor roaster. The result achieved indicated that the average particle residence time inside the roaster was increased successfully in order to compensate for the longer reaction time required to roast micro-pellets at lower levels of O2 in the fluidizing air.http://www.saimm.co.za

The recovery of manganese products from ferromanganese slag using a hydrometallurgical route

The ferromanganese industry is under pressure to deal with the slag arising from the production of ferromanganese, which is discarded in landfills or slag heaps. This material poses an environmental and health risk to surrounding ecosystems and communities, and disposal costs are increasing. Ferromanganese slag contains an appreciable amount of residual manganese metal, which can be exploited. Previous work has shown that the slag can be leached fully, while rejecting the silica to a residue. The methods that were investigated to recover manganese from the leach solution included hydroxide precipitation to upgrade the leach solution followed by manganese carbonate precipitation to produce a pure manganese carbonate product or a manganese carbonate furnace feed material, which would be recycled to increase manganese recoveries in the production of ferromanganese. In addition, electrowinning of electrolytic manganese dioxide from the leach solution was studied. The methods were compared in terms of selectivity, costs, and product quality. Co-recovery of the leach residue, which is a potential cement additive, is discussed. Among the methods investigated to upgrade the pregnant leach solution, hydroxide precipitation utilizing ammonia to adjust the pH appears to be the most effective in removing major impurities such as iron, aluminium, and silica to less than 1 ppm. The manganese carbonate and impure manganese carbonate furnace feed products met quality specifications. However, although the production of these materials was technically viable, the large amounts of base reagent that were required to raise the pH, and the associated high operating costs, rendered the process uneconomic. An optimization study was therefore carried out with the primary objective to determine the ideal acid amount to be utilized in the waterstarved digestion stage, thereby decreasing acid and base consumption while optimizing the quality of the pregnant leach solution, and producing a leach residue that contained <1% Mn. The outcome was an economically viable process. Additional benefits included an increase in the manganese content of the impure manganese carbonate furnace feed material, and a substantial reduction in the dilution of the pregnant leach solution, thereby maintaining high manganese concentrations that rendered the solution viable for electrowinning of electrolytic manganese dioxide, the production of which yielded a current efficiency of 74%.Paper written on project work carried out in partial fulfilment of B. Eng. (Metallurgical Engineering)http://www.saimm.co.za/am201

The effect of electrolyte additives on cathode surface quality during copper electrorefining

The use of electrolyte additives to smoothen cathode deposits during copper deposition is practised worldwide. These additives absorb on the cathode surface and take part in the electrochemical crystallization process. However, these additives also affect the quality of the cathodes when they are inadequately controlled. Electrolyte additives used by Palabora are glue, thiourea, Avitone and chloride. Their effects were determined on cathode quality, the size of the current density region that gives the desired compact morphology, and current efficiency. This was done in a small-scale cell. Small cells have different hydrodynamics from industrial-scale cells, which makes it difficult to simulate the operation of industrial cells in a laboratory. The approach used here was to use a rotating cylinder cathode to attain controlled hydrodynamics. The rotation speed was chosen to give a diffusion layer thickness that is similar to that of an industrial-scale cell. It was shown that even fairly small changes in the additive levels can significantly affect the cathode morphology, and the current density range over which this morphology can be obtained.The University of Pretoria and Palabora Copper Mining Ltd. are thanked for financial assistance.http://www.saimm.co.za