The existence of a double S-shaped process curve during reactive magnetron sputtering

The four dimensional parameter space (discharge voltage and current and reactive gas flow and pressure) related to a reactive Ar/O2 DC magnetron discharge with an aluminum target and constant pumping speed was acquired by measuring current-voltage characteristics at different oxygen flows. The projection onto the pressure-flow plane allows us to study the well-known S-shaped process curve. This experimental procedure guarantees no time dependent effects on the result. The obtained process curve appears not to be unique but rather two significantly different S-shaped curves are noticed which depend on the history of the steady state target condition. As such, this result has not only an important impact on the fundamental description of the reactive sputtering process but it can also have its consequences on typical feedback control systems for the operation in the transition regime of the hysteresis during reactive magnetron sputtering

Postpartum amenorrhoea-galactorrhoea associated with hyperprolactinaemia and pituitary enlargement in primary hypothyroidism

We report a 36-year-old woman with primary hypothyroidism revealed by postpartum amenorrhoea-galactorrhoea associated with hyperprolactinaemia and suprasellar pituitary enlargement on magnetic resonance imaging (MRI). On thyroid hormone replacement therapy all clinical, biochemical, radiological and endocrine abnormalities disappeared. Hyperplasia of pituitary thyrotrophs and/or lactotrophs seems to be responsible for the pituitary enlargement seen on MRI

Anomalous effects in the aluminum oxide sputtering yield

The sputtering yield of aluminum oxide during reactive magnetron sputtering has been quantified by a new and fast method. The method is based on the meticulous determination of the reactive gas consumption during reactive DC magnetron sputtering and has been deployed to determine the sputtering yield of aluminum oxide. The accuracy of the proposed method is demonstrated by comparing its results to the common weight loss method excluding secondary effects such as redeposition. Both methods exhibit a decrease in sputtering yield with increasing discharge current. This feature of the aluminum oxide sputtering yield is described for the first time. It resembles the discrepancy between published high sputtering yield values determined by low current ion beams and the low deposition rate in the poisoned mode during reactive magnetron sputtering. Moreover, the usefulness of the new method arises from its time-resolved capabilities. The evolution of the alumina sputtering yield can now be measured up to a resolution of seconds. This reveals the complex dynamical behavior of the sputtering yield. A plausible explanation of the observed anomalies seems to originate from the balance between retention and out-diffusion of implanted gas atoms, while other possible causes are commented

Phytoextraction of phosphorus for ecological restoration: application of soil additives

The European Habitats Directive urges the European member states to take measures for maintaining and restoring natural habitats. In Flanders (Belgium) and the Netherlands, the surface area of nature reserves is intended to be enlarged with 38 000 ha and 150 000 ha, respectively, what is mainly to be realised on former agricultural land. In order to restore species rich nature habitats on former agricultural land, it is crucial to decrease the availability of nutrients and a limitation for plant growth by at least one nutrient should be ensured. The former fertilization of P in the agricultural context results in an immense P pool fixated to the soil and this is one of the main problems hindering the ecological restoration. We focus on an alternative restoration method, the phytoextraction of P, also P-mining. This is the deprivation of soil P with a crop with high P-use efficiency and non-P fertilization. This method allows the gradual transition from agricultural land use towards nature management. Up until now there have only been estimations of the P-mining duration time from the initial phase of the mining-process. In order to estimate the P-extraction over time the experiments take place on a soil-P-chronosequence. A controlled pot experiment was set up with soil from three former agricultural sites with different soil-P-levels, Lolium perenne was sown and chemical and biological compounds were added to enhance the bioavailability of P for plant-uptake. The additives used were two concentrations of humic acids, phosphorus solubilising bacteria and arbuscular mycorrhizal fungi. Largest effects of the soil additions on the biomass production were measured in the lowest soil-P-level. Limitation by P in the Mid and Low P soils was very pronounced. The phytoextraction of P will slow down with soil P level decreasing in time. The effect of the soil additions is discussed

Onderzoek naar mogelijkheden voor natuurontwikkeling in de depressie van de Moervaart in relatie tot fosfor

In het strategisch plan van de Gentse Kanaalzone (2005) is vastgelegd om het historisch passief en de huidige beleidsrelevante natuur te compenseren in de onmiddellijke nabijheid van het zeehavengebied. Hiervoor werden verschillende zoekzones aangeduid, o.a. in de Moervaartdepressie op grondgebied Gent en gedeeltelijk grondgebied Moerbeke. Om de schade aan de natuur ten gevolge van de uitbreiding van de Gentse haven te compenseren dient de volgende ‘natte’ natuur te worden ontwikkeld: 72 ha open water, waarvan 58 ha (80%) open water van minstens 50 cm diep en 14 ha (20%) open water van maximaal 50 cm diep, 13 ha rietland, 2 ha grote zeggenvegetatie, 90 ha permanent soortenrijk grasland, waarvan 60/70 ha soortenrijk grasland met kleine landschapselementen en 20/30 ha open nat grasland met brede sloten (aansluitend op het rietland), 16 ha zandig kaal terrein als schiereilanden, omringd door dieper water. Gelet op het langdurig intensief agrarisch gebruik van de beoogde deelgebieden en gelet op de voorziene vernatting nodig voor de realisatie van de natuurdoelen, is het wenselijk inzicht te krijgen in de huidige concentraties aan biobeschikbaar fosfor (P) alsook in de hoeveelheid P dat in de toekomst ten gevolge van interne eutrofiëring biobeschikbaar kan komen. Kennis van de uitgangssituatie met betrekking tot P in de bodem zal bijdragen tot het bepalen van een meest optimaal voorstel van omvormingsbeheer en inrichtingsmaatregelen. Via specifieke maatregelen (verschralen door maaien en afvoeren, uitmijnen, ontgronden) kan eventueel de P stock verlaagd worden in functie van de beoogde natuurontwikkeling. Om te weten of en welke maatregelen best genomen worden dient eerst echter inzicht verkregen te worden in de uitgangssituatie. De doelstellingen van natuurcompensatie kunnen worden opgesplitst in twee grote luiken: (I) de creatie van helder open water, waarbij de nalevering van fosfaten uit de waterbodem te voorkomen is, (II) de ontwikkeling van soortenrijke graslanden van het type dotterbloemgrasland, glanshavergrasland, kamgrasland, … en de ontwikkeling van grote zeggenvegetaties en rietland, waarbij nagekeken moet worden of de huidige bodemcondities met betrekking tot P geschikt zijn. Dit onderzoek brengt de huidige concentraties aan biobeschikbaar P, alsook de hoeveelheid P die door vernatting kan gemobiliseerd worden in kaart. Ook de bodemzuurtegraad en de zwavel- en ijzerconcentraties werden onderzocht omwille van hun invloed op P. De gegevens werden geïnterpreteerd in relatie tot de beschikbare grenswaarden voor het ontwikkelen van open water en de beoogde vegetatietypes, alsook in functie van het voorstellen van milderende maatregelen (maaibeheer, uitmijnen, ontgronden)