A nesting conformation of the 5′-bromo-1′,3′-xylyl-18-crown-5·tert-butylammonium hexafluorophosphate complex; the correlation of the structures of crown ether complexes in the solid state and in solution

Single-crystal X-ray analysis of the 5′-bromo-1′,3′-xylyl-18-crown-5· tert-butylammonium hexafluorophosphate complex shows that the complex is of the “nesting” type in which the cation and the aryl group are on the same face of the macroring and that the macroring has a (ag+a) (ag−a) (ag+a) (ag−a)(ag+a) (ag−a) conformation

Adsorption of aminefluorides on human enamel

Changes in surface characteristics of ground and polished human enamel after adsorption of two types of aminefluorides (AmF 297 and AmF 335) have been studied. After adsorption of aminefluorides from solutions with concentrations up to 10 mM for 2 min followed by rinsing of the surface with distilled water, contact angle measurements were carried out to yield surface free energies and ellipsometry was performed to yield the adsorbed layer thickness. In a separate experiment on powdered enamel, set up in an analogous way, zeta potential changes after adsorption of aminefluorides were determined in a 10 mM potassium phosphate buffer at pH 7·0. Surface free energies decreased from 88 erg·cm−2 to 52 erg·cm−2 and 35 erg·cm−1 after adsorption of AmF 297 and AmF 335 respectively at c = 1 mM. Increasing the aminefluoride concentration in solution did not affect the values obtained. Zeta potentials, originally −36 mV, became positive after adsorption, while ellipsometry indicated the buildup of adsorbed layers with a thickness between 3 run and 12 nm. All three types of experiments indicated that both AmF 297 and AmF 335 form an adsorbed monolayer on ground and polished enamel at a concentration of 1 mM. Negligible additional adsorption takes place at higher concentrations under the present experimental circumstances. In vivo, adsorbed aminefluoride layers will be rapidly covered by adsorbed protein layers, shielding both the adsorbed aminefluoride layer as well as its physicochemical characteristics. This effect has been studied in vivo by measuring surface free energy changes of ground and polished enamel, with AmF 297 and AmF 335 adsorbed at c = 2·5 mM as a function of the time, these samples were carried by test persons in partial dentures. On both types of AmF-coated enamel the surface free energies increased within 30 min to values approaching the one obtained previously for pellicle-coated ground and polished enamel (110 ± 9 erg·cm−2)

The permanence debate

E. Kintisch (“Deforestation moves to the fore in Copenhagen,” News of the Week, 11 December 2009, p. 1465) identifies a number of issues hindering an agreement on Reducing Emissions from Deforestation and Forest Degradation (REDD). However, he does not mention permanence, which has dogged the REDD discussions for some time (1). Many negotiators fear that reductions in loss of forest carbon stocks may be credited and rewarded now, but that the forest may later disappear (whether cut or affected by die-off due to climate changes). They contrast this scenario with that of fossil fuels, for which they argue that savings are permanent. This argument is flawed. There is a finite quantity of fossil fuel underground. Clean technology slows the rate at which it is extracted and burned, but eventually it will all be converted to CO2. REDD will slow the rate at which carbon is emitted from forests in an analogous way. The conceptual muddle about permanence occurs when people confuse “stocks” with the “rate of change of stocks.” Reduced emissions from deforestation and forest degradation are, like fossil fuel reductions, calculated on the basis of lowered annual losses compared to business as usual, not on the basis of stock remaining. There is only one difference between stocks of fossil carbon and stocks of living carbon, in terms of permanence. Carbon lost due to deforestation or forest degradation in one place can be replaced by reforestation or enhancing carbon stocks in degraded forests elsewhere, whereas fossil fuels cannot be replaced at all

SUSMETRO : Impact Assessment Tools for Food Planning in Metropolitan Regions : IA tools and serious gaming in support of sustainability targets for food planning, nature conservation and recreation

By offering a series of decision support tools for stakeholders of metropolitan regions, SUSMETRO facilitates and enables evidence-based decision making by means of ‘serious gaming’. Making use of the Phase 1 thematic maps such as on agricultural competitiveness, nature conservation and recreational values, stakeholders can compare impacts of traditional versus innovative forms of agricultural production. The SUSMETRO Impact Assessment tool provides information on the expected effects of spatial planning with regard to the self-supportive capacities of the region (ecological footprint) and the share of recreational and nature conservation facilities (land use functions), offering cost-benefit calculations regarding the expected economic revenues. The whole process is embedded in a Landscape Character Assessment process and guided by Knowledge Brokerage procedures to strengthen the science-policy interface. In sum, the SUSMETRO approach allows a wide range of stakeholders to co-develop images for sustainable Metropolitan Agriculture

Melamine in sojaschilfers, oorzaak van verschillen tussen laboratoria

In november 2008 is door het bedrijfsleven in een tweetal partijen diervoedergrondstoffen (sojaschilfers/-meel) melamine aangetroffen op niveaus tussen 40 en 800 mg/kg. Naar aanleiding hiervan heeft de VWA aan RIKILT verzocht om deze monsters (genomen door het bedrijfsleven) te analyseren op melamine en daarnaast, ten behoeve van de risicobeoordeling, op de hydrolyseproducten ammeline, ammelide en cyanuurzuu