Biomass fly ash effect on fresh and hardened state properties of cement based materials

Cement pastes and mortars were prepared by replacing ordinary Portland cement with different dosages of biomass fly ashes (0, 10, 20 and 30% BFA) whilst in dry condition. The effect of BFA on the flow behaviour (spread on table and rheology), setting time, temperature of hydration and electrical resistivity was studied in this experimental research. Increasing the amount of BFA in the compositions required extra dosage of water, as a result of particles fineness, tendency for agglomeration and retention/absorption of water molecules. As a consequence, the relative amount of free water diminishes and the flowability is poorer. The introduction of BFA also led to an increase in setting time, while the resistivity obtained from the impedance measurements tends to be lower than the reference paste (ash-free). The higher concentration of mobile species in the pore solution, namely sodium ions introduced by the ash, explains that tendency. The hydration temperature of cement pastes tends to decrease with the level of cement to ash replacement. Between the two tested ashes (from grate and fluidized sand bed furnaces), differences in particle size and shape, in the amount of residual organic matter and concentration of inorganic components define minor changes in the workability and setting behaviour. Therefore, the introduction of biomass fly ashes affects the hardened state features but do not compromise them. (C) 2015 Elsevier Ltd. All rights reserved

Insecticidal activity of a recombinant knottin peptide from Loxosceles intermedia venom and recognition of these peptides as a conserved family in the genus

Loxosceles intermedia venom comprises a complex mixture of proteins, glycoproteins and low molecular mass peptides that act synergistically to immobilize envenomed prey. Analysis of a venom-gland transcriptome from L. intermedia revealed that knottins, also known as inhibitor cystine knot peptides, are the most abundant class of toxins expressed in this species. Knottin peptides contain a particular arrangement of intramolecular disulphide bonds, and these peptides typically act upon ion channels or receptors in the insect nervous system, triggering paralysis or other lethal effects. Herein, we focused on a knottin peptide with 53 amino acid residues from L. intermedia venom. The recombinant peptide, named U2-sicaritoxin- Li1b (Li1b), was obtained by expression in the periplasm of Escherichia coli. The recombinant peptide induced irreversible flaccid paralysis in sheep blowflies. We screened for knottin-encoding sequences in total RNA extracts from two other Loxosceles species, Loxosceles gaucho and Loxosceles laeta, which revealed that knottin peptides constitute a conserved family of toxins in the Loxosceles genus. The insecticidal activity of U-2-SCTX-Li1b, together with the large number of knottin peptides encoded in Loxosceles venom glands, suggests that studies of these venoms might facilitate future biotechnological applications of these toxins