Comparative pyrolysis kinetics of heavy oil and its SARA fractions using distributed activation energy model

The pyrolysis behaviors of Qingdao vacuum residue(QD-VR)and its SARA(saturates,aromatics,reins,and asphaltenes)fractions were evaluated by thermo-gravimetric with mass spectrometer(TG-MS).The pyrolysis kinetics were determined by Friedman,one-parallel and four-parallel distributed activation energy model(DAEM),respectively.The results indicated that the pyrolysis behavior of QD-VR was similar to that of aromatics.For saturates,the release of H_(2),CH_(4),CO,and CO_(2) occurred in 80-400℃,while the temperature range for QD-VR and other fractions is 200-800℃.The average activation energy(Ea)via Friedman method was 179.72 kJ/mol and increased with the conversion ratio.One-parallel Gaussian DAEM was more suitable to describe the pyrolysis process of the single SARA fractions,while four-parallel Gaussian DAEM was more suitable to describe the pyrolysis process of heavy oil.Furthermore,comparing the weighted E_(a) from one-parallel(227.64 kJ/mol)and four-parallel Gaussian DAEM(204.63 kJ/mol),the results suggested that during pyrolysis process of heavy oil,there was an interaction between the SARA fractions,which could reduce the E_(a) of heavy oil pyrolysis.Specifically,during heavy oil pyrolysis,resins and asphaltenes could increase the E_(a) of saturates and aromatics,while saturates and aromatics could decrease the E_(a) of resins and asphaltenes.

Blockade of complement activation in bullous pemphigoid by using recombinant CD55-CD46 fusion protein

To the Editor:Bullous pemphigoid(BP)is an autoimmune blistering disease that is caused by autoantibodies and is associated with complement activation.[1]Autoantibody-mediated complement activation is involved in BP pathogenesis.Complement-regulatory proteins(CRPs)including CD35,CD46,CD55,and CD59 comprise an important class of regulatory proteins in the complement system that control the enzyme cascades,assembly of the membrane-attack complex,and complement system homeostasis.[2]Classically,both CD55 and CD46 negatively regulate complement system activation by inhibiting the production of new C3 and C5 convertases and accelerating the degradation of those already formed,thereby protecting cells from complement activation-induced damage.