Removal of phenols from aqueous solutions by emulsion liquid membranes

The present study deals with the extraction of phenols from aqueous solutions by using the emulsion liquid membranes technique. Besides phenol, two derivatives of phenol, i.e., tyrosol (2-(4-hydroxyphenyl)ethanol) and p-coumaric acid (4-hydroxycinnamic acid), which are typical components of the effluents produced in olive oil plants, were selected as the target solutes. The effect of the composition of the organic phase on the removal of solutes was examined. The influence of pH of feed phase on the extraction of tyrosol and p-coumaric was tested for the membrane with Cyanex 923 as an extractant. The use of 2% Cyanex 923 allowed obtaining a very high extraction of phenols (97-99%) in 5-6 min of contact time for either single solute solutions or for their mixtures. The removal efficiency of phenol and p-coumaric acid attained equivalent values by using the system with 2% isodecanol, but the removal rate of tyrosol was found greatly reduced. The extraction of tyrosol and p-coumaric acid from their binary mixture was also analysed for different operating conditions like the volume ratio of feed phase to stripping phase (sodium hydroxide), the temperature and the initial concentration of solute in the feed phase.     

Functionalized Microparticles Producing Scaffolds in Combination with Cells

The development of biologically instructive biomaterials with application for tissue regeneration has become the focus of intense research over the last years. This work reports a novel approach for the production of three‐dimensional constructs for tissue engineering applications based on the assembly of chitosan microparticles exhibiting specific biological response with cells. Chitosan microparticles with a size range between 20 and 70 μm are functionalized with platelet derived growth factor (PDFG‐BB). The functionalization is achieved by previous immobilization of an anti‐PDGF‐BB antibody, using a water‐soluble carbodiimide. When incubated with a cocktail of growth factors‐platelet lysates, the previously functionalized particles are able to target PDGF‐BB from the protein mixture. In vitro studies are carried out focusing on the ability of these systems to promote the assembly into a stable 3D construct triggered by the presence of human adipose stem cells, which act as crosslinker agents and induce the formation of a hydrogel network. The presence of immobilized growth factors gives to this system a biological functionality towards control on cell function. It is also bioresponsive, as cells drive the assembly process of the microgel. These versatile biomimetic microgels may provide a powerful tool to be used as an injectable system for non‐invasive tissue engineering applications with additional control over cellular function by creating specific microenvironments for cell growth.     

An ultrastructural study of spermiogenesis in two species of Sitophilus (Coleoptera: Curculionidae).

The spermiogenesis of Sitophilus zeamais and Sitophilus oryzae, the maize and the rice weevil, respectively, was studied by light microscopy and scanning and transmission electron microscopy. Sitophilus spp. is the most widespread and destructive primary pest of stored cereals in the world. The spermiogenesis occurs within cysts. There are approximately 256 germ line cells per cyst. Inside each cysts, all the spermatids are in the same stage of maturation. The ultrastructure of the spermatozoa of S. zeamais and S. oryzae is similar to that described for other beetles. The head is formed by a three-layered acrosome with the perforatorium, the acrosomal vesicle, the extra-acrosomal layer and the nucleus. The flagellum has the typical axoneme formed by a 9+9+2 microtubules arrangement, two mitochondrial derivatives and two accessory bodies. The typical pattern for Curculionidae spermatozoa described here may provide useful information for future phylogenetic analysis of the superfamily Curculionoidea.     

Carcinogens stimulate intrachromosomal homologous recombination at an endogenous locus in human diploid fibroblasts

Mitotic recombination is believed to play an important role in the development of many cancers. An improved system has been developed to detect reversion of an intragenic DNA duplication, as a model for intrachromosomal homologous recombination. The 'LNtd' strain of human fibroblasts, derived from a Lesch-Nyhan donor, produces no detectable hypoxanthine phosphoribosyltransferase (HPRT) activity due to a 13.7-kilobase-pair DNA insertion duplicating exons 2 and 3 of the HPRT locus. These cells are therefore sensitive to selection in HAT medium, against cells lacking functional HPRT enzyme. Clonal reversion to HAT resistance occurs spontaneously at 1-3 x 10(-5)/cell/generation, and can be induced by brief exposure to a variety of carcinogenic agents. Six known carcinogens, including two (diethylstilbestrol and nickel chloride) which were non-mutagenic in Salmonella by Ames HIS-reversion tests, showed dose-dependent induction of LNtd reversion by a maximum of 2.4- to > 11-fold over controls (each p < 0.01). In contrast, 5 non-carcinogenic agents, including two 'Ames-positive' chemicals, sodium azide and 8-hydroxyquinoline, evoked no more than a 1.7-fold increase in reversion (not significant). The molecular events associated with reversion to HAT-resistance were characterized, relative to the parental strain, in HATR clones derived from either untreated or carcinogen-treated cells. Both the intron-3:intron-1 junction situated between the duplicated HPRT segments in LNtd cells (amplified by polymerase chain reaction), and a restriction fragment corresponding to the duplicated HPRT DNA (assessed by Southern-blot hybridization), were lost from the majority of HATR revertant clones, whether they arose spontaneously or following exposure to Cr(VI) or ultraviolet light. These results imply that HATR reversion is induced in LNtd cells by carcinogenic treatments, through a mechanism consistent with homologous recombination, and is highly concordant with induction of in vivo carcinogenesis by the same agents.     

Microwave absorption properties of a conductive thermoplastic blend based on polyaniline

Summary Conductive thermoplastic blends of polystyrene and polyaniline doped with dodecylbenzene sulfonic acid, DBSA and polystyrene sulfonic acid were prepared in an internal mixer. We used a block copolymer of styrene and butadiene as compatibilizer. Different formulations were tested according to a statistical response surface method. The electrical conductivity and the microwave radiation absorbing properties of the blends were evaluated. The concentration of the compatibilizer and polyaniline and the blend film thickness affect the attenuation properties of the materials.     

Cryogenic temperature performance of modulation-doped field-effect transistors

Reports S-parameter measurements of AlInAs/GaInAs/InP modulation-doped field-effect transistors (MODFETs) at cryogenic temperatures. The current gain at 80 K is 3 dB higher than at 300 K, and the current gain cutoff frequency f/sub T/ increases from 32 GHz at 300 K, to 42 GHz at 80 K, which is the first observation of higher f/sub T/ by direct measurement.<>     

Use of IgM monoclonal reagents licensed for tube tests in column agglutination technology

BACKGROUND: Red cell (RBC) phenotyping using column agglutination technology (CAT) is currently limited by the reagents formulated in the system. To overcome this limitation, it was investigated whether monoclonal IgM reagents licensed for use with tube tests produced valid results with CAT. STUDY DESIGN AND METHODS: Commercial CAT, does not contain antisera, was used to evaluate Procedures A (40 microL of reagent and 10 microL of 4% RBCs) and B (50 microL of reagent and 50 microL of 0.8% RBCs) with or without incubation at room temperature. In Study 1, reagents were tested to determine whether potentiators inhibit the passage of antigen-negative RBCs through the column. In Study 2, CAT sensitivity was measured by the use of potency titrations to define a procedure for each reagent that matched or exceeded that of the tube method. In Study 3, the specificity of each reagent was determined in parallel with the CAT and tube tests. Typing of 1644 samples was performed. RESULTS: Study 1: Free passage was obtained with all reagents. Study 2: Immediate-spin methods using CAT produced the same results as the tube method. Study 3: With 8048 comparisons made, discrepant results were found in 32 transfused patients and in 6 cord blood samples, mainly with Lewis reagents. With comparison of CAT and the standard tube method, complete agreement was obtained with Kell reagents, 99.9-percent agreement with Kidd reagents, and 98.9-percent and 99.4-percent agreement with Lewis reagents. CONCLUSION: Most examined reagents seem suitable for use with CAT.     

Innovative approaches in integrated assessment modelling of European air pollution control strategies – Implications of dealing with multi-pollutant multi-effect problems

In this paper, crucial aspects of the implications and the complexity of interconnected multi-pollutant multi-effect assessments of both air pollution control strategies and the closely related reduction of greenhouse gas emissions will be discussed. The main aims of the work described here are to identify the core problems which occur when trying to apply current state-of-the-art methodology to conduct integrated assessments – in this context, cost-benefit assessment (CBA) as well as cost-effectiveness assessment (CEA) – using sophisticated computer models and propose solutions to the problems identified. The approaches described will display the integrated use of databases, efficient algorithms and already existing software tools and models in a unified model framework. The first part of the paper discusses the need for new developments in one particular field of Integrated Assessment Models (IAMs), which is the use of (typically) country-specific single pollutant abatement cost curves, which have been applied in a large number of modelling approaches with the aim to find cost-effective solutions for given air quality targets. However, research conducted to find such cost-effective solutions for the non-linear problem of tropospheric ozone abatement (dealing with two primary pollutants and their rather complex relationship to form tropospheric ozone, [see] [Friedrich, R., Reis, S. (Eds.), 2000. Tropospheric Ozone Abatement – Developing Efficient Strategies for the Reduction of Ozone Precursor Emissions in Europe. Springer Publishers] identified basic problems of cost curve based approaches even in this two-pollutant case. The approach discussed here promises to solve the key problems identified, making extensive use of databases in order to provide fast and high quality model input for CEA and CBA. In addition to that, the application of Genetic Algorithms will be discussed as a means to address extremely complex, vast solution spaces which are typical for the tasks IAMs are set to solve nowadays. As the application of the model in extensive assessment studies is currently under way, it is yet too early for a full evaluation of lessons learned. However, initial tests of performance and behaviour have shown robust and promising results.