Selection for scrapie resistance decreased inbreeding rates in two rare sheep breeds in the Netherlands

An attempt to balance selection intensity and conservation of genetic diversity was made in the national program for breeding for scrapie resistance in the Netherlands. The ARR allele is associated with resistance to scrapie. In the Netherlands a breeding program was started on a voluntary basis in 2001 and starting 2004 the use of ARR/ARR rams was obligatory. In some rare breeds there were so few ARR/ARR rams that the risk of high inbreeding and associated loss of genetic diversity would be unacceptably high. Based on computer simulations predicting the inbreeding rates for several breeds exemptions on the obligatory breeding program were allowed. In this paper the ARR frequencies and associated inbreeding rates are analyzed as an indication of loss in genetic diversity during the years of scrapie selection in two breeds: the “Zwartbles schaap” (Black-blazed sheep) and the “Melkschaap” (Friesian-Zealand Milksheep)

The nature of the potassium compound acting as a promoter in iron-alumina catalysts for ammonia synthesis

The chemical form of the potassium promoter on an iron-alumina catalyst during ammonia synthesis has been studied by two methods, viz, (i) the measurement of the equilibrium constant of the process KNH2 + H2 KH + NH3, and (ii) chemical analysis of the used catalyst. The equilibrium constant measurements gave K723 = (12.9 ± 0.5) × 10−3, ΔHf2980(KNH2) = −119 ± 3 kJ mol−1 and S2980(KNH2) = 109 ± 4 J mol−1 K−1. The chemical analysis showed that no KNH2 is present on the catalyst during synthesis. From these results and with the aid of thermodynamic considerations it is concluded that KNH2, K and K2O are not stable compounds under conditions of ammonia synthesis. X-Ray diffraction showed that part of the potassium reacts with Al2O3, probably leaving part of the potassium in the form of KOH which is quite stable under ammonia synthesis conditions

Highly luminescent perovskite–aluminum oxide composites

In this communication we report on the preparation of CH3NH3PbBr3 perovskite/Al2O3 nanoparticle composites in a thin film configuration and demonstrate their high photoluminescence quantum yield. The composite material is solution-processed at low temperature, using stable alumina nanoparticle dispersions. There is a large influence of the alumina nanoparticle concentration on the perovskite morphology and on its photoluminescence

Perovskite solar cells prepared by flash evaporation

A simple vacuum deposition method for the preparation of high quality hybrid organic-inorganic methylammonium lead iodide perovskite thin films is reported. When sandwiched in between organic charge transporting layers, such films lead to solar cells with a power conversion efficiency of 12.2%

Persistent photovoltage in methylammonium lead iodide perovskite solar cells

Open circuit voltage decay measurements are performed on methylammonium lead iodide (CH3NH3PbI3) perovskite solar cells to investigate the charge carrier recombination dynamics. The measurements are compared to the two reference polymer-fullerene bulk heterojunction solar cells based on P3HT:PC60BM and PTB7:PC70BM blends. In the perovskite devices, two very different time domains of the voltage decay are found, with a first drop on a short time scale that is similar to the organic solar cells. However, two major differences are also observed. 65-70% of the maximum photovoltage persists on much longer timescales, and the recombination dynamics are dependent on the illumination intensity.Comment: 5 pages, 3 figure

Risico van inteelt bij paarden

Alle stamboeken zijn zich bewust van het risico van inteelt binnen paardenpopulaties. Daarnaast weten ze ook dat het fokken op lange termijn niet gemakkelijk is. De themadag ‘Balans tussen inteelt en biodiversiteit bij paarden’ heeft in oktober alle theoretische achtergronden rondom een gezonde fokkerij op een rij gezet. Daarna gaf een aantal stamboekverenigingen een toelichting op het eigen belei

Polymer-Encapsulated Halide Perovskite Color Converters

An easy process to fabricate highly luminescent and color-pure polymer-encapsulated halide perovskite color converters is reported. Methylammonium lead bromide (MAPbBr3) with an additive of amantadine hydrochloride is prepared by dry mechanochemical synthesis together with an encapsulating polymer. (In this report, poly(methyl methacrylate), polystyrene, and polyethylene oxide are investigated.) The composite material is heated and pressed into a thin disk exhibiting strong luminescent properties. By adjusting the weight percentage of the perovskite in the polymer, the disk can be opaque or transmissive. The disks are stable in air for over 2 months. By inserting a secondary emitter, white light can be obtained by illuminating it with a blue light source