Homogeneous vs. heterogeneous catalysis for hydrogen evolution by a nickel(ii) bis(diphosphine) complex.

Nickel(ii) bis(diphosphine) complex 1 bearing carboxylic acid functional groups at the periphery has been prepared and characterized. Its catalytic ability towards the hydrogen evolution reaction (HER) has been evaluated under different experimental conditions: (i) under homogeneous electrocatalysis in acetonitrile using trifluoroacetic acid as the proton source, (ii) under homogeneous photocatalysis in aqueous solution using Ru(bpy)32+ (where bpy = 2,2'-bipyridine) as the sensitizer and ascorbic acid as the sacrificial electron donor, and (iii) under heterogeneous electrochemical conditions upon grafting onto mesoporous TiO2. The results show that complex 1 is a competent and efficient catalyst for the HER under both homogeneous electro- and photochemical conditions, while undergoes rapid deactivation once attached onto the TiO2 surface.

[Egyptian mummies as anthropological artifacts].

Ancient human remains like Egyptian mummified bodies cannot be considered on a physical anthropological perspective only. So severe and invasive were the operations on the body, so various were the materials involved in the preservation techniques, so complicated was the embalming and wrapping procedure according to specific rituals, that the final result, the mummy, is to be considered a highly composite product. The human remains are a relevant part of it indeed, but a very wide set of information can be taken.