Slab – column connections that are subjected to combined gravity and horizontal loading during an earthquake are prone to premature failure due to punching shear. Traditional solutions to avoid punching failure and to increase the displacement capacity of this type of connection include using stirrups and double-headed studs as shear reinforcement. The use of High-Performance Fiber Reinforced Concrete (HPFRC) in a small region of the slab around the column as a substitute for traditional solutions is investigated in this paper, because this material has the potential to reduce labor and material costs. To fulfill this objective, four slab specimens with a thickness of 150 mm were tested under combined gravity and reversed horizontal drifts. The results are discussed in detail. The experimental variables considered were the top flexural reinforcement ratio, the size of the HPFRC zone and the intensity of the gravity load. Previously published tests that serve as reference specimens are used to compare the results. The behavior of the specimens with HPFRC was substantially improved compared to the reference specimens in terms of drift capacity: from only 1.0% drift to above 5.5%, even though a very small quantity of HPFRC was used, extended up to only 1.5 times the effective depth of the slab from the face of the column. Specimens with HPFRC also behaved better when compared to specimens with High-Strength Concrete (HSC). Side effects of using HPFRC in the slab in the vicinity of the column include an increase of the unbalanced moment transfer capacity and lateral stiffness, as well as a reduction of the deflections of the slab.

Geobacter sulfurreducens is a widely applied microorganism for the reduction of toxic metal salts, as an electron source for bioelectrochemical devices, and as a reagent for the synthesis of nanoparticles. In order to understand the influence of metal salts, and of electron transporting, multiheme c-cytochromes on the electron flux during respiration of G. sulfurreducens, the reduction kinetic of Fe³⁺, Co³⁺, V⁵⁺, Cr⁶⁺, and Mn⁷⁺ containing complexes were measured. Starting from the resting phase, each G. sulfurreducens cell produced an electron flux of 3.7 × 10⁵ electrons per second during the respiration process. Reduction rates were within ± 30% the same for the 6 different metal salts, and reaction kinetics were of zero order. Decrease of c-cytochrome concentrations by downregulation and mutation demonstrated that c-cytochromes stabilized respiration rates by variation of their redox states. Increasing Fe²⁺/heme levels increased electron flux rates, and induced respiration flexibility. The kinetic effects parallel electrochemical results of G. sulfurreducens biofilms on electrodes, and might help to optimize bioelectrochemical devices.