Suitability of sawdust from three tropical timbers for wood-cement composites

Construction material rising cost and global demand for economically-sustainable and environmentally-friendly building resources have necessitated the use of sawdust-cement composite. Wood constituents and cement incompatibility hinder its production and need careful selection of the timber. Sawdust suitability from Triplochiton scleroxylon, Entandrophragma cylindricum and Klainedoxa gabonensis for wood-cement composite was determined by identifying their chemical constituents and their composites’ physico-mechanical properties. T. scleroxylon recorded the minimum total extractive (6.12%), lignin (29.89%) and holocellulose (56.38%) and K. gabonensis the maximum (9.31, 31.59 and 57.5% respectively). Ash content was higher for T. scleroxylon (7.6%) but lower for K. gabonensis (1.53%). T. scleroxylon boards were stronger [Modulus of Elasticity (MOE) = 696.1 N/m 2 ] and more moisture-resistant [Moisture Absorption (MA) = 8.8%] than E. cylindricum (MOE = 625.9 N/m 2 ; MA = 9.5%). K. gabonensis boards crushed after manufacturing due to its incompatibility with cement. T. scleroxylon sawdust is suitable for wood-cement composites due to its more compatible chemical constituents (i.e., lower extractive, lignin, holocellulose contents and more ash) and its boards’ excellent physico-mechanical properties than those for the other timbers. Its sawdust-cement composites could be utilized for cladding and walling. The use of sawdust would increase green building resource base and reduce environmental pollution

Quantification of cAMP and cGMP analogs in intact cells: pitfalls in enzyme immunoassays for cyclic nucleotides

Immunoassays are routinely used as research tools to measure intracellular cAMP and cGMP concentrations. Ideally, this application requires antibodies with high sensitivity and specificity. The present work evaluates the cross-reactivity of commercially available cyclic nucleotide analogs with two non-radioactive and one radioactive cAMP and cGMP immunoassay. Most of the tested cyclic nucleotide analogs showed low degree competition with the antibodies; however, with Rp-cAMPS, 8-Br-cGMP and 8-pCPT-cGMP, a strong cross-reactivity with the corresponding cAMP and cGMP, respectively, immunoassays was observed. The determined EIA-binding constants enabled the measurement of the intracellular cyclic nucleotide concentrations and revealed a time- and lipophilicity-dependent cell membrane permeability of the compounds in the range of 10–30% of the extracellular applied concentration, thus allowing a more accurate prediction of the intracellular analog levels in a given experiment