Assigning pupils to tutor groups in a comprehensive school

Comprehensive schools in the UK have the annual task of assigning their intake of new pupils to tutor groups. This case study describes how the problem has been addressed at one such school, where several factors are taken into account in order to make the groups as similar as possible and, since pupils have an induction day in June when they assemble in their tutor groups and meet their new tutors, where the time scale is short. Manual allocation has been used in the past, needing many staff-hours to achieve a satisfactory result. Heuristics implemented on a spreadsheet have enabled substantial savings in staff time and given more evenly balanced tutor groups.     

Proteome Analysis of Aflibercept Intervention in Experimental Central Retinal Vein Occlusion

Aflibercept is a frequently used inhibitor of vascular endothelial growth factor (VEGF) in the treatment of macular edema following central retinal vein occlusion (CRVO). Retinal proteome changes following aflibercept intervention in CRVO remain largely unstudied. Studying proteomic changes of aflibercept intervention may generate a better understanding of mechanisms of action and uncover aspects related to the safety profile. In 10 Danish Landrace pigs, CRVO was induced in both eyes with an argon laser. Right eyes were treated with intravitreal aflibercept while left control eyes received isotonic saline water. Retinal samples were collected 15 days after induced CRVO. Proteomic analysis by tandem mass tag-based mass spectrometry identified a total of 21 proteins that were changed in content following aflibercept intervention. In retinas treated with aflibercept, high levels of aflibercept components were reached, including the VEGF receptor-1 and VEGF receptor-2 domains. Fold changes in the additional proteins ranged between 0.70 and 1.19. Aflibercept intervention resulted in a downregulation of pigment epithelium-derived factor (PEDF) (fold change = 0.84) and endoplasmin (fold change = 0.91). The changes were slight and could thereby not be confirmed with less precise immunohistochemistry and Western blotting. Our data suggest that aflibercept had a narrow mechanism of action in the CRVO model. This may be an important observation in cases when macular edema secondary to CRVO is resistant to aflibercept intervention.     

Chemically induced dynamic nuclear polarizations (CIDNP) and kinetic studies of the decomposition of di-t-butylmagnesium, -zinc,and -mercury

Pulsed Fourier transform NMR was used to study ¹H-CIDNP arising from the thermolysis of di-t-butylmagnesium 1 and -zinc 2 and from the thermolysis and photolysis of di-t-butylmercury 3 in deuterated hydrocarbons as solvents. The decomposition of 1, 2, and 3 leads to metal, to the polarized disproportionation products isobutane 4 and isobutene 5 (rate constant k_d), and to the unpolarized combination product 2,2,3,3-tetramethylbutane 6 (rate constant k_c). Analysis of the ratio k_d/k_c as well as the activation entropies for the decomposition establish a radical mechanism for the main process. In the decomposition of 1 and 2 an A/E multiplet polarization of 4 and 5 is observed. This is opposite to the E/A polarization of these products arising during the thermolysis of 3. The photolysis of 3, however, leads to an A/E polarization of 4 and 5. The different phases of the multiplets indicate a decomposition of dialkylmercury in a cage reaction. Dialkylmagnesium and -zinc, however, decompose in a free-radical reaction of uncorrelated t-butyl pairs.     

Structure,thermal stability and decomposition of bis-allyl-zinc compounds

The structure, thermal stability and decomposition of solutions of diallylzinc (I), bis(2-methylallyl)zinc (II), bis(3-methylallyl)zinc (III) and bis(3,3-dimethylallyl)zinc (IV) in deuterated solvents, have been investigated by¹H NMR and by kinetic measurements at temperatures between ?125 and +180°C. At room temperature I, II, III and IV are dynamic systems and are best described as being rapidly equilibrating mixtures of all isomeric σ-allyl forms; the NMR spectra are averages weighted according to the relative concentrations of the respective forms. I displays a¹H NMR spectrum of a static σ-allyl system only below ?125°C and II only below ?115°C. At temperatures above 100°C the thermal decomposition of I–IV results in coupling of the allyl groups, decomposition via radicals being the major process. The coupled products exhibit CIDNP, in which the multiplet polarisations confirm a decomposition via randomly diffusing allyl radicals. In the allyl radicals CH₂CR¹CR²R³ an alternating spin density was proved experimentally. The thermal stability decreases in the order I > II > III > IV.     

The assignment of diastereotopic menthyl groups by two-dimensional NMR

The ¹³C and ¹H NMR spectra of (–)-bis[1R, 3 R, 4S]menthylphosphine (1) are assigned by two-dimensional double quantum NMR and ¹³C? ¹H shift correlation diagrams. The variable temperature spectra of 1 indicate hindered rotation about the P? C bonds.