Posidonia oceanica (L.) fibers as a potential low-cost adsorbent for the removal and recovery of orthophosphate

Adsorption efficiency of orthophosphate from aqueous solution onto Posidonia oceanica fibers (POF) as a raw, natural and abundant material was investigated and compared with other common natural materials. A series of batch tests were undertaken to assess the effect of the system variables, i.e. initial aqueous orthophosphate concentration, contact time, adsorbent dosage, pH and temperature. Results indicate that orthophosphate uptake increased with increasing initial orthophosphate concentration, temperature and adsorbent dosage and decreased with increasing pH values. The maximum adsorption capacity (Q(m)) determined from the Langmuir isotherm was calculated to be 7.45 mg g(-1) for the studied orthophosphates concentration range of 15-100 mg L(-1), pH 7; adsorbent dosage of 2 g L(-1) and temperature of 20±2°C. The adsorption data were very well described by the pseudo-second order model predicting a chemisorption process. The energy dispersive spectroscopy (EDS) and FTIR analysis before and after adsorption of orthophosphate onto POF showed that the main involved mechanisms are ligand exchange between orthophosphate and Cl(-), SO(4)(2-) and OH(-) and precipitation with calcium. In comparison with other natural adsorbents, raw POF could be considered as one of the most efficient natural materials for the removal of orthophosphate with the possibility of agronomic reuse.     

Database design and querying within the fuzzy semantic model

Fuzzy semantic model (FSM) is a data model that uses basic concepts of semantic modeling and supports handling fuzziness, uncertainty and imprecision of real-world at the attribute, entity and class levels. The paper presents the principles and constructs of the FSM. It proposes ways to define the membership functions within all the constructs of the FSM. In addition, it provides a proposal for specifying FSM schema and introduce a query language adapted to FSM-based databases.     

Effect of Contamination on Reinforcing Bar-Concrete Bond

Current specifications require the removal of reinforcing bar contaminants that reduce bond prior to placing concrete. This study focused on the interactions of contaminant type, bar size, epoxy coating, concrete strength, and test method (beam and direct pullout). The majority of the beam tests showed the bond strength was not significantly affected, with certain exceptions. However, the direct pullout tests revealed a significant reduction of bond strength in most situations. Although the bond strength was still greater than that required by code, it is recommended that specifications for removal of contaminants should not be relaxed until further study is performed.     

FE analysis of the behaviour of microcracks in the cement mantle of reconstructed acetabulum in the total hip prosthesis

Cracking of cement mantle of joint arthoplasties is one possible factor in the loosening of cemented replacements. The analysis of the fracture behaviour of cement in such case can be an effective means being able to contribute to the prediction of the lifespan of the various types of cemented prostheses. In this study, the three-dimensional finite element method was used to analyse the fracture behaviour of cement of reconstructed acetabulum by computing the stress intensity factor along the crack front. The obtained results show that the risk of crack propagation by opening effect is more important than the sliding and the tearing ones when the crack is located at the free edge of the cement mantle. The sliding effect is dominant when the crack is inclined at 45° from the free edge of the cement mantle.     

Optimum design of pendulum‐type tuned mass dampers

The equations of motion are derived for a translational single degree of freedom system equipped with a ‘pendulum‐type’ tuned mass damper (TMD) under dynamic force and base acceleration excitations. The complex frequency response functions are obtained. Following response minimization procedures, the optimum parameters of the TMD under random white noise excitations are determined. The effect of the TMD in reducing the response is expressed in terms of an equivalent viscous damping. The optimum design parameters and the corresponding efficiency of the TMD under both wind and earthquake dynamic loads are presented in design charts. The effect of the structure inherent and aerodynamic damping on the optimum parameters is studied and simplified charts to account for such effect are provided. Moreover, a design chart for the over‐optimum‐damped TMDs is presented. The translational‐type TMD is treated as a special case of the pendulum‐type. Copyright © 2005 John Wiley & Sons, Ltd.     

Ductility characteristics of fiber-reinforced-concrete beams reinforced with FRP rebars

To mitigate the corrosion problem caused by steel reinforcement, a study was initiated to develop a nonferrous hybrid reinforcement system for concrete beams by incorporating continuous fiber-reinforced-polymer (FRP) rebar and fiber-reinforced-concrete (FRC) containing randomly distributed polypropylene fibers. This paper describes the flexural performance of this FRP/FRC hybrid reinforcement system as well as FRP/plain concrete beams that served as references. Test results showed that the crack widths of FRP/FRC beams were smaller than those of FRP/plain concrete beams at the proposed service load. The compressive strains at the top fiber of concrete in FRP/FRC beams were larger than 0.004 due to the added polypropylene fibers. In addition, the ductility indices evaluating the FRP reinforced members were discussed. It is found that the ductility indices for all the tested beams were above the minimum requirement of 4. The addition of fibers improved the flexural behavior by increasing the ductility level more than 30%, when compared to the companion beam.     

Assessment of green roof thermal behavior: A coupled heat and mass transfer model

Green roofs have a positive effect on the energy performance of buildings, providing a cooling effect in summer, along with a more efficient harnessing of the solar radiation due to the reflective properties found inside the foliage. For assessing these effects, the thermodynamic model was developed as well as the thermo-physical properties of the green roof components were characterized. Its typologies and vegetation styles should also be studied. The proposed model is based on energy balance equations expressed for foliage and soil media. In this study, the influence of the mass transfer in the thermal properties and evapotranspiration were taken into account. We then added the water balance equation into our model and performed a numerical simulation. By assuming the outdoor conditions, the roof support temperature and the drainage water as inputs, the model evaluates the temperatures evolution at foliage and soil ground levels. A parametric study was performed using the proposed model to classify green roofs depending on the considered climate condition. Comparisons were undertaken with a roof slab concrete model; a significant difference (of up to 30 °C) in temperature between the outer surfaces of the two roofs was noticed in summer. The model was experimentally validated according to green roof platform, which was elaborated. The mass transfer effect in the subtract was very effective in reducing the model errors. Simulation results show that the use of vegetation in the roof building improves not only thermal comfort conditions, but the energy performance of a building.     

Integration of an M-phthalocyanine layer into solution-processed organic photovoltaic cells for improved spectral coverage

Photovoltaic devices made from blended poly(3,3?-didodecylquaterthiophene) (PQT-12) and [6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM) incorporating an additional interlayer of M-phthalocyanine (M-Pc) have been characterized using current-voltage response, UV-visible absorption and external quantum efficiency. The introduction of H₂Pc, CuPc, ClInPc or TiOPc layers improves device performance compared to conventional bulk-heterojunction PQT-12:PCBM cells without M-Pc. Devices with M-Pc show increased absorption and free charge generation at longer wavelengths and have higher open circuit voltage. Polymorphic changes from solvent interaction are observed in TiOPc films during fabrication. Power conversion efficiencies of 0.79% are achieved for this modified bulk-heterojunction solar cell.     

Effect of germination on the nitrogenous constituents,protein fractions, in vitro digestibility and antinutritional factors of fenugreek seeds (trigonella foenum graecum L.)

This study was designed to determine the effect of germination on nitrogenous constituents, protein fractions, in vitro digestibility and antinutritional factors (namely trypsin inhibitor and haemagglutinin) of the Egyptian fenugreek seeds Geiza 2 variety. After 96 h of germination, there was 18% decrease in the dry weight of seeds, a slight increase of total nitrogen (TN), a decrease of protein nitrogen (PN) and a marked increase of both non-protein nitrogen (NPN) and free amino acid nitrogen (FAAN). Non-protein nitrogen other than FAAN, amido nitrogen and ammonia nitrogen also increased. The protein fractions (namely albumin, globulin, prolamin and glutelin) were separated according to their solubilities in different solvents. The ratio between the four protein fractions in ungerminated seeds was 4:3.5:2.8:1 and became 2:6.5:7.7:1 after germination as calculated on the basis of their PN.Trypsin inhibitor activity per gramme of fenugreek was found to be higher by 66% in germinated fenugreek than ungerminated seeds. Both ungerminated and germinated fenugreek was found devoid of the haemagglutinin activity.Germination resulted in a slight increase in pancreatic digestibility, 33.7% decrease in digestibility by pepsin followed by pancreatin, while a small decrease was found in peptic digestibility.