You can get the final version of Francesco Celani et al. paper here:
Key points are that
1. Use of local E-Glass fibres appears to allow high level of adsorption of mono atomic Hydrogen produced from Catalytic surface modified Constantan, that can then provide impulsive action back on the Constantan by the formation of H2. This appears to increase excess heat.
2. The addition of knots into wire creates discontinuities/non-equilibrium which appears to increase excess heat.
3. Addition of Fe and, in turn Iron oxides into wire and especially knots in wire, increases excess heat.
4. Use of Low Work Function additive Strontium.