On the complex formation of iron(III) bromide in the space-demanding solvent N,N′-dimethylpropyleneurea and the structure of the trisbromoiron(III) complex in solution and crystalline state

The complex formation between iron(III) and bromide has been studied calorimetrically in N,N′-dimethylpropyleneurea (DMPU), and the structure of the DMPU solvated tribromoiron(III) complex has been studied in solution by extended X-ray absorption fine structure (EXAFS) and large angle X-ray scattering (LAXS), and in solid state by EXAFS and single crystal X-ray diffraction. The calorimetric study showed that iron(III) forms three medium strong bromide complexes in DMPU, and the thermodynamic pattern strongly indicates that all complexes are formed in entropy driven substitution reactions. In DMPU solution, the tribromoiron(III) complex has a regular trigonal planar configuration with a mean Fe-Br bond distance of 2.36 Å, and without any solvent molecules strongly bound to iron(III). In the solid state, however, the structure is a slightly distorted trigonal bipyramid, with one short and two slightly longer Fe-Br bonds, 2.37 and 2.44 Å, respectively, in a somewhat distorted trigonal plane, and two DMPU solvent molecules (mean Fe-O bond distance 1.98 Å) in the apical positions. The DMPU solution of iron(III) bromide and the [FeBr₃(dmpu)₂] crystals are both blackish red.     

High-voltage isoelectric focusing with pharmalyte: Field strength and temperature distribution,zone sharpening,isoelectric spectra,and pI determinations

In isoelectric focusing it is theoretically advantageous to use the highest voltages possible. Limitations are due to uneven heat evolution because of uneven conductivity of the individual carrier ampholyte molecules and/or insufficient cooling. The availability of a new carrier ampholyte. Pharmalyte, and a new flatbed apparatus with improved properties has made it possible to perform experiments at very high voltages. The results are discussed in terms of zone sharpness, resolution, and temperature profile. A method is proposed for accurate pI determinations, considering the temperature dependence of pI and the actual temperature in the gel.     

Short-term LDL cholesterol-lowering efficacy of plant stanol esters

Background  

The short-term cholesterol-lowering efficacy of plant stanol esters has been open to debate, and the data from different clinical studies with hypercholesterolemic subjects are variable, partly due to lack of systematic studies. Therefore, we investigated the time in days needed to obtain the full cholesterol-lowering effect of stanol esters in hypercholesterolemic subjects.