Treatment of electroplating wastewater containing Cu2+, Zn2+ and Cr(VI) by electrocoagulation

The performance of electrocoagulation, with aluminium sacrificial anode, in the treatment of metal ions (Cu2+, Zn2+ and Cr(VI)) containing wastewater, has been investigated. Several working parameters, such as pH, current density and metal ion concentrations were studied in an attempt to achieve a higher removal capacity. Results obtained with synthetic wastewater revealed that the most effective removal capacities of studied metals could be achieved when the pH was kept between 4 and 8. In addition, the increase of current density, in the range 0.8-4.8 A dm(-2), enhanced the treatment rate without affecting the charge loading, required to reduce metal ion concentrations under the admissible legal levels. The removal rates of copper and zinc were found to be five times quicker than chromium because of a difference in the removal mechanisms. The process was successfully applied to the treatment of an electroplating wastewater where an effective reduction of (Cu2+, Zn2+ and Cr(VI)) concentrations under legal limits was obtained, just after 20 min. The electrode and electricity consumptions were found to be 1 g l(-1) and 32 A h l(-1), respectively. The method was found to be highly efficient and relatively fast compared to conventional existing techniques.     

Characterization of β-In2−xAlxS3 thin films prepared by chemical spray pyrolysis technique

Indium sulfide (In₂S₃) is a good window or buffer layer for photovoltaic application. In this work, β-In_2?xAl_xS₃ thin films with different thicknesses (400, 442, 646 and 714 nm) are successfully synthesized on heated glass substrates using a chemical spray pyrolysis technique. The thin film thickness effect on the structural, optical and photoluminescence (PL) properties of β-In_2?xAl_xS₃ material is studied. The X-ray diffraction patterns suggest the formation of β-In₂S₃ cubic phase preferentially oriented towards (400) direction. The level of the residual dislocation seems to be reduced to 3.12 × 10⁹ lines mm^?2 for the optimum thickness (646 nm) for which the β-In_2?xAl_xS₃ film crystallinity is the best one. In order to enhance the electrical properties, β-In_2?xAl_xS₃ layers are annealed in air at 400 °C for different annealing times (15, 30 and 45 min). The minimum resistivity, maximum Hall mobility and carrier concentration are found for β-In_2?xAl_xS₃ films annealed for 30 min. All samples have high transmittance of about 75 % but the wide band gap (E_g = 3.32 eV) is obtained for this optimum thickness. This result indicates good optical quality of β-In_2?xAl_xS₃ layers. Defects-related PL properties are also discussed.     

Fabrication and characterization of Cu2ZnSnS4 thin films deposited by spray pyrolysis technique

We have investigated synthesis conditions and some properties of sprayed Cu₂ZnSnS₄ (CZTS) thin films in order to determine the best preparation conditions for the realization of CZTS based photovoltaic solar cells. The thin films are made by means of spraying of aqueous solutions containing copper chloride, zinc chloride, tin chloride and thiourea on heated glass substrates at various temperatures. In order to optimize the synthesis conditions of the CZTS films, two series of experiments are performed. In the first series the sprayed duration was fixed at 30 min and in the second it is fixed at 60 min. In each series, the substrate temperature was changed from 553°K to 633°K. The X-ray diffraction shows, on one hand, that the best crystallinity was obtained for 613°K as substrate temperature and 60 min as sprayed duration. On the other hand, these CZTS films exhibit the kesterite structure with preferential orientation along the [112] direction. Atomical Force Microscopy was used to determine the grain sizes and the roughness of these CZTS thin film. After the annealing treatment, we estimated the optical band-gap energy of the CZTS thin film exhibiting the best crystallinity as 1.5 eV which is quite close to the optimum value for a solar cell.     

Damage evolution and infrared thermography in woven composite laminates under fatigue loading

An analytical model based on cumulative damage has been used for predicting the damage evolution in composite materials. The model is verified with experimental data from a carbon/epoxy composite fatigued under tension–tension load. Fatigue tests of specimens have been monitored with an infra-red thermography system. By analysing the temperature of the external surface during the application of cyclic loading, it is possible to evaluate the damage evolution. The model agrees well with the experimental data, and it can be used to predict the evolution of damage in composites.     

Biocompatibility of heparin-grafted hemodialysis membranes: impact on monocyte chemoattractant protein-1 circulating level and oxidative status

This prospective observational study aimed at evaluating efficacy and biocompatibility performances of the new heparin-coated Evodial dialyzers with/without systemic heparin reduction. After a 4-week wash-out period with reference polysulfone F70S dialyzers, 6 hemodialysis patients were sequentially dialyzed with Evodial, F70S, and Evodial dialyzers using 30% heparin reduction, each period of treatment was 4 weeks. Removal rates (RR) (urea, creatinine, and β2-microglobulin), dialysis dose, and instantaneous clearances (urea and creatinine) were measured as well as inflammatory (C-reactive protein, fibrinogen, interleukin 6, tumor necrosis factor α, and monocyte chemoattractant protein-1) and oxidative stress (OS) (superoxide anion, homocysteine, and isoprostanes) parameters at the end of each study period. Patients treated with Evodial or F70S dialyzers for 4 weeks presented comparable dialysis efficacy parameters including urea and creatinine RR, dialysis dose and instantaneous clearances. By contrast, a significantly lower but reasonably good β2-microglobulin RR was achieved with Evodial dialyzers. Regarding biocompatibility, no significant difference was observed with inflammation and OS except for postdialysis monocyte chemoattractant protein-1 which significantly decreased with Evodial dialyzers. Thirty percent heparinization reduction with Evodial dialyzers did not induce any change in inflammation but led to an improvement in OS as demonstrated by a decrease in postdialysis superoxide production and predialysis homocysteine and isoprostane. This bioactive dialyzer together with heparin dose reduction represents a good trade-off between efficacy and biocompatibility performance (improvement in OS with a weak decrease in efficacy) and its use is encouraging for hemodialysis patients not only in reducing OS but also in improving patient comorbid conditions due to lesser heparin side effects.     

Détermination expérimentale des propriétés hydriques des pâtes de ciment durcies—Mise en évidence des phénomènes d'hystérésis

Résumé Dans cet article, les auteurs comparent les propriétés structurales et hydriques de deux pates de ciment durcies, l'une ordinaire (CO) et l'autre (CH) représentative de bétons à très hautes performances dont l'utilisation est croissante à l'heure actuelle dans le domaine de la construction. L'analyse de la structure poreuse montre le caractère fortement compact de la microstructure de la pate de ciment durcie CH. Ce caractère est également illustré par les isothermes de désorption et d'adsorption de vapeur d'eau. Les courbes obtenues dans deux laboratoires sont comparées. Elles mettent en évidence la faible sensibilité des matériaux à très hautes performances vis-à-vis des variations de l'humidité relative de leur environnement, dans le domaine HR>50%. Ceci laisse prévoir des déformations hygrométriques (retrait de dessiccation) réduites dans ce domaine, par rapport aux matériaux ordinaires. Les résultats des mesures de perméabilité à la vapeur d'eau montrent l'influence du paramètre teneur en eau. La pate CH présente, dans le domaine des fortes humidités relatives, une perméabilité plus faible que celle de la pate CO. La perméabilité à la vapeur d'eau de ces pates de ciment durcies reste toutefois très faible par rapport à celle d'autres matériaux de construction.

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Experimental determination of moisture properties of hardened cement pastes, showing hysteresis effects

In this paper, the structure and moisture properties of two hardened cement pastes are compared. One paste (CO) is an ordinary mix. The other paste (CH) is representative of high-performance concretes which are today more and more widely used in construction. The pore structure analysis shows the very dense microstructure of the hardened cement paste CH. This feature is also pointed out with water vapour desorption and adsorption isotherms. The curves obtained in two laboratories are compared. They highlight that high-performance materials are fairly insensitive to environmental relative humidity variations, in the range RH>50%. Smaller hygral strains (drying shrinkage) can be expected in this range, as compared to ordinary mixes. The results of water vapour permeability measurements show the influence of the water content. The permeability obtained for the hardened cement paste CH is lower than for CO, in the high relative humidity range. The water vapour permeability of these hardened cement pastes is, however, very low as compared to other building materials.

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Note de la rédaction Mme V. Baroghel Bouny travaille au Laboratoire Central des Ponts et Chaussées (LCPC), Membre Titulaire de la RILEM.     

Preparation and Characterization of Magnetite–Chitosan Nanoparticles and Evaluation of Their Cytotoxicity Effects on MCF7 and Fibroblast Cells

Nowadays, magnetic nanoparticles play a key role in drug treatment. However, if they are uncoated, they might aggregate and cause embolism in drug delivery. To avoid this, they are generally coated with polymers. In this investigation, magnetic nanoparticles (MNPs) were coated with chitosan through in situ co-precipitation process and their properties in addition to their cytotoxicity in MCF7 and fibroblast cells were analyzed. The results showed MNPs–chitosan nanoparticles would contain an average mean diameter of 32 nm and a saturation magnetization (M _S) value of 38.87 emu/g. To characterize the synthesized nanoparticles in terms of structural, morphological and magnetic properties, Fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA) and vibrating sample magnetometry (VSM) studies were used. Toxicity test was also done to investigate whether their presence would cause any toxicity in the body; in addition, antibacterial assay was done to analyze if nanoparticles could be used as an antimicrobial agent.     

Optimizing dock configuration and staffing in decentralized receiving

In manufacturing facilities, shipping and receiving traditionally have been concentrated in one or two areas of the building. The widespread introduction of just-in-time shipping policies in US manufacturing companies during the past 15 years, as well as the common use of decentralized receiving in the Japanese automobile industry, has motivated the consideration (and occasionally the adoption) of dock configurations to support decentralized receiving (also known as perimeter receiving). By providing multiple access points along the perimeter of the building, decentralized receiving generally reduces the time and cost associated with moving purchased parts to the locations within the facility where they are used, but also results in increased cost of construction, maintenance, and operation for docks and associated truck access/egress, as well as additional interior floorspace requirements. We develop an optimization-based procedure to determine which of several possible dock areas to construct, how many doors or gates each should have, how many unloading and internal material handling staff should be assigned to each group, and which inbound materials each group should handle. We consider the amortized cost of constructing and equipping the docks, the amortized cost of material handling equipment to support the unloaders and material handlers, the cost of operating the material handling equipment, and labor costs for both unloading and internal material handling.     

Mutations in PDX1, the human lipoyl-containing component X of the pyruvate dehydrogenase-complex gene on chromosome 11p1, in congenital lactic acidosis

We have identified and sequenced a cDNA that encodes an apparent human orthologue of a yeast protein-X component (ScPDX1) of pyruvate dehydrogenase multienzyme complexes. The new human cDNA that has been referred to as "HsPDX1" cDNA was cloned by use of the "database cloning" strategy and had a 1,506-bp open reading frame. The amino acid sequence of the protein encoded by the cDNA was 20% identical with that encoded by the yeast PDX1 gene and 40% identical with that encoded by the lipoate acetyltransferase component of the pyruvate dehydrogenase and included a lipoyl-bearing domain that is conserved in some dehydrogenase enzyme complexes. Northern blot analysis demonstrated that the major HsPDX1 mRNA was 2.5 kb in length and was expressed mainly in human skeletal and cardiac muscles but was also present, at low levels, in other tissues. FISH analysis performed with a P1-derived artificial chromosome (PAC)-containing HsPDX1 gene sublocalized the gene to 11p1.3. Molecular investigation of PDX1 deficiency in four patients with neonatal lactic acidemias revealed mutations 78del85 and 965del59 in a homozygous state, and one other patient had no PDX1 mRNA expression.     

Embedded representation of fracture in concrete with mixed finite elements

As an alternative to the smeared and discrete crack representations, an embedded representation of fracture for finite element analysis of concrete structures is presented. The three-field Hu–Washizu variational statement is extended to bodies with internal discontinuities. The extended variational statement is then utilized for formulating elements with a discontinuous displacement field. The new elements are capable of modelling different deformation modes of an internal discontinuity at the element level. The satisfactory performance of the embedded crack representation is verified by several case studies on concrete fracture.