Characterisation of L-[3H]glutamate binding to fresh and frozen crude plasma membranes isolated from cerebral cortex of adult rats

Specific [3H]glutamate binding to fresh crude plasma membranes (CPMs) was compared with binding to frozen CPMs and the optimal conditions for the binding to frozen CPMs isolated from cerebral cortex of adult rats were determined. Freezing reduced [3H]glutamate binding (3.5-fold), and pre-incubation of previously frozen membranes followed by three washes increased binding (4.5-fold) when compared to fresh samples. CPMs washed once, pre-incubated at 37 degrees C and washed 3 times was adopted as the most adequate condition for the binding assay of frozen membranes. In a Cl(-)-containing medium, [3H]glutamate binding (Bmax=97.9 pmol/mg, Kd=349.68 nM) to this frozen CPM preparation was significantly displaced by excess quisqualic acid (QA) (65%), L-2-amino-4-phosphonobutyric acid (L-AP4) (35%), trans-1-aminocyclopentane-1,3-dicarboxylate (1S,3R-ACPD) (25%) and alfa-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) (25%). In a Cl(-)-free medium, binding (Bmax=44.14 pmol/mg, 311 nM) was significantly displaced by QA (45%), L-AP4 (25%), ACPD (25%), AMPA (25%), kainic acid (20%) and N-methyl-D-aspartate (15%).     

Evaluation of flocs resistance and reflocculation capacity using the LDS technique

In a previous paper we have shown the added value of using LDS to monitor flocculation. It can supply, simultaneously, information on flocs size and structure and enlighten flocculation kinetics and mechanisms. In this paper, LDS is applied to study deflocculation and reflocculation processes of precipitated calcium carbonate (PCC) induced by cationic polyacrylamides, when different types of shear forces are applied. LDS can detect the influence of polymer characteristics and concentration as well as of the type of shearing, on flocs resistance and reflocculation degree, which depend on flocs structure and on the type of bonds between particles. As expected, flocs formed by bridging mechanism reflocculate with difficulty while flocs formed by patching reflocculate to a higher degree. Flocs resulting from reflocculation are more compact than the original ones, as assessed by the mass fractal dimension. Reflocculation is also lower when the flocs are submitted to superficial shearing than when they are submitted to sonication. Shearing induced by sonication is sufficient to break down the flocs in many fragments while the increase of pump speed only detaches particles by erosion, at the flocs surface, where bonds are weaker. Results prove that LDS is useful to monitor deflocculation and reflocculation processes and to predict floc resistance under different conditions. Moreover, the whole study demonstrates the benefit of using LDS for a complete evaluation of flocculants performance in the different stages of flocculation: aggregation, stabilization, deflocculation and reflocculation.     

Imaging findings in hypertensive encephalopathy

Hypertensive encephalopathy is a neurologic syndrome caused by a marked and rapid rise of blood pressure above baseline levels. Efficacy of current anti-hypertensive drugs greatly diminished the frequency of this situation in which diagnosis is essentially based on clinical parameters. This can justify the few papers found in radiologic literature. Nevertheless it is sometimes important to exclude ischemic or hemorrhagic complications or establish a differential diagnosis with other neuropathologic conditions. Then a striking imagiologic picture of focal or diffuse reversible edema of cerebral white matter can be found. We present three clinical cases of hypertensive encephalopathy. Imagiologic findings are reviewed and correlated with the pathophysiologic basis of the disease.     

Oxidation of Benzene Catalyzed by 2,2′-Bipyridine and 1,10-Phenantroline Cu(II) Complexes

The use of mononuclear Cu(II) 2,2′-bipyridine and 1,10-phenantroline complexes as catalysts in the oxidation of benzene, using hydrogen peroxide and tert-butyl hydroperoxide as oxidant in CH₃CN/H₂O solution is presented. The reactions were carried out at 25 and at 50 °C. The complexes [Cu(bipy)₃]Cl₂ · 6H₂O (1), [Cu(bipy)₂Cl]Cl · 5H₂O (2), [Cu(bipy)Cl₂] (3), [Cu(phen)₃]Cl₂ · 7H₂O (4), [Cu(phen)₂Cl]Cl · 5H₂O (5), [Cu(phen)Cl₂] (6) were able to oxidize benzene into phenol, hydroquinone and p-benzoquinone. Highest conversion (22%) was obtained using [Cu(Phen)Cl₂] (6) as catalyst.     

Study on the fatigue strength of AA 6082-T6 adhesive lap joints

A research study on the fatigue behaviour of aluminium alloy adhesive lap joints was carried out to understand the effect of surface pre-treatment and adherends thickness on the fatigue strength of adhesive joints. The adherend material used for the experimental tests was an aluminium alloy 6082-T6 in the form of thin sheets, and the adhesive used was a high strength epoxy (Araldite 420 A/B). The surface preparation included an abrasive preparation (AP joints) and sodium dichromate–sulphuric acid etch (CSA joints).A maximum fatigue strength was obtained for the CSA surface treatment with a 1.0 mm adherends’ thickness. The fastest fatigue damage was related with a high surface roughness and a high stress perpendicular to adhesive surface, which helps to promote the adhesive failure. A numerical analysis was also performed to understand the effect of the adherends thickness on the stress level. Results showed an increase of the out-of-plane peak stresses with the increase of adherends thickness.     

The effectiveness of a biological treatment with Rhizopus oryzae and of a photo-Fenton oxidation in the mitigation of toxicity of a bleached kraft pulp mill effluent

Huge efforts have been made both in adopting more environmental-friendly bleaching processes, and in developing advanced oxidation processes and more effective biological treatments for the reduction of deleterious impacts of paper mill effluents. Even so, the success of such treatments is frequently reported in terms of chemical parameters without a proper evaluation of the effluent's toxicity mitigation. This is the first study reporting an exhaustive evaluation of the toxicity of a secondary bleached kraft pulp mill effluent, after either tertiary treatment with the soft-rot fungi Rhizopus oryzae or with a photo-Fenton oxidation, using a battery of freshwater species. As it has been reported the photo-Fenton/UV treatment has proved to be the most effective in reducing the colour and the COD (chemical oxygen demand) of the effluent. Nevertheless, extremely low EC₅₀ values were reported for almost all species, after this tertiary treatment. The treatment with R. oryzae was less effective in terms of colour removal and COD reduction, but proved to be the most promising in reducing toxicity.     

Palladium on Calcium Carbonate Combined to 2‐Hydroxypropyl‐α/β‐cyclodextrins: A Selective Catalytic System for Aqueous Heck Coupling and Hydroarylation

An efficient, selective and recoverable catalytic system for ligand‐free aqueous Heck reactions using hydroxypropylated cyclodextrins (HPCDs) and palladium on calcium carbonate (Pd/CaCO₃) is highlighted. Remarkably, stereo‐ and chemoselectivities could be tuned by the cavity size of cyclodextrins, exploiting the relevance of host‐guest interactions. UV‐Vis experiments have led to strong evidence concerning an interplay between Pd(II) and α‐HPCD, possibly ascribed to a reduction/stabilization effect of CDs. Unexpectedly, hydroarylation was the favored pathway with acrylonitrile which provided access to 3‐phenylpropionitrile derivatives without usual hydride donors. Finally, determination of soluble Pd(0/II) via AAS enabled the definition of a predominant homogeneous mechanism in which TONs over 5000 were observed.     

Changes in fatty acid composition and electrolyte leakage of ‘Hayward’ kiwifruit during storage at different temperatures

Exposure to low storage temperature induces changes in electrolyte leakage and fatty acids composition, in a way depending on the plant tissue. Those changes alter the response of the fruit to storage conditions. The influence of storage temperature on ripening, fatty acids composition and electrolyte leakage of ‘Hayward’ kiwifruit were investigated. Harvested fruit were stored at 0, 5, 10, 15 and 20 °C for 5, 12 and 17 days. Measurements of SSC, firmness, flesh colour, fatty acid composition and electrolyte leakage were performed during the experiment. Kiwifruit did not fully ripen during the 17 days storage at any temperature. The major fatty acid component in ‘Hayward’ kiwifruit consisted of linolenic, followed by oleic, palmitic, linoleic and stearic acid. Membrane permeability and unsaturated/saturated fatty acid ratio increased during storage in all treatments. The highest increase was during the first 5 days and at the lowest temperatures. The increase in unsaturated/saturated fatty acid ratio was caused mainly by a decrease in palmitic and an increase in oleic acids. Stearic, linoleic and linolenic acids had insignificant changes during storage. The main increase in electrolyte leakage and unsaturated/saturated fatty acid ratio occurred during the first storage days and at lower temperatures, probably as a response of the tissue to an adaptation to the new stress storage conditions.