Removal of disperse dye from aqueous solution by novel adsorbent prepared from biomass plant material

The adsorption of Disperse Orange 25 (3-[N-ethyl-4-(4-nitrophenylazo) phenylamino] propionitrile) onto activated carbon was investigated in a batch system with respect to contact time, carbon dosage, pH and temperature from aqueous solutions. The Langmuir, Freundlich and Dubinin–Radushkevich (D–R) adsorption models were applied to describe the equilibrium isotherms and the isotherm constants were also determined. The Langmuir isotherm model agrees with the experimental data well. Maximum adsorption capacity (q_max) of Disperse Orange 25 onto adsorbent was 118.93 mg g⁻¹ at 20 °C. The first-order, pseudo-second-order kinetic models and the intraparticle diffusion model were used to describe the kinetic data and the rate constants were evaluated as well. The experimental data fitted very well to pseudo-second-order kinetic model. The results show that activated carbon prepared from Euphorbia rigida by sulfuric acid chemical activation could be employed as low-cost material to compare with commercial activated carbon for the removal of disperse dyes from effluents.     

Scintillation index of flat-topped Gaussian laser beam in strongly turbulent medium

In a strongly turbulent medium, the scintillation index of flat-topped Gaussian beams is derived and evaluated. In the formulation, unified solution of Rytov method is utilized. Our results correctly reduce to the existing strong turbulence scintillation index of the Gaussian beam, and naturally to spherical and plane wave scintillations. Another checkpoint of our result is the scintillation index of flat-topped Gaussian beams in weak turbulence. Regardless of the order of flatness, scintillations of flat-topped Gaussian beams in strong turbulence are found to be determined mainly by the small-scale effects. For large-sized beams in moderate and strongly turbulent medium, flatter beams exhibit smaller scintillations.     

Long-term characterization of firing dynamics of spontaneous bursts in cultured neural networks

Extracellular action potentials were recorded from developing dissociated rat neocortical networks continuously for up to 49 days in vitro using planar multielectrode arrays. Spontaneous neuronal activity emerged toward the end of the first week in vitro and from then on exhibited periods of elevated firing rates, lasting for a few days up to weeks, which were largely uncorrelated among different recording sites. On a time scale of seconds to minutes, network activity typically displayed an ongoing repetition of distinctive firing patterns, including short episodes of synchronous firing at many sites (network bursts). Network bursts were highly variable in their individual spatio-temporal firing patterns but showed a remarkably stable underlying probabilistic structure (obtained by summing consecutive bursts) on a time scale of hours. On still longer time scales, network bursts evolved gradually, with a significant broadening (to about 2 s) in the third week in vitro, followed by a drastic shortening after about one month in vitro. Bursts at this age were characterized by highly synchronized onsets reaching peak firing levels within less than ca. 60 ms. This pattern persisted for the rest of the culture period. Throughout the recording period, active sites showed highly persistent temporal relationships within network bursts. These longitudinal recordings of network firing have, thus, brought to light a reproducible pattern of complex changes in spontaneous firing dynamics of bursts during the development of isolated cortical neurons into synaptically interconnected networks.     

Evaluation of a methodology to determine texture characteristics of maize (Zea mays L.) tortilla

Maize (Zea mays L.) tortilla is the primary staple food of the Mexican people, with annual consumption estimated at 12 millions tons. Despite this huge volume of consumption, tortillas are commercially produced with inconsistent quality, mainly in terms of texture characteristics. Different methods to evaluate the texture of maize tortillas have been reported, but the values obtained and their parameters have not yielded reliable results, largely because the methods used do not reflect homogeneous elements for comparison. In addition, evaluation of the reliability of methods for comparing tortilla texture as well as the equipment used has been difficult, as such information perhaps remains largely unpublished. In this study, the reliability of two tortilla sample shapes (rectangle and briquet) and some of the quality parameters (maximum force, total area under curve, area to reach maximum force, elasticity and elongation) from tensile and cut force tested with a texture meter were evaluated. According to the results, the briquet shape of the tortilla samples was better (than the rectangle shape) for determining tensile and elasticity. In regard to cutting force, both the rectangle and the briquet shape presented good repeatability. For tensile and cutting-force curves, the maximum force was the parameter with the highest reliability, 0.95 and 0.99, respectively. The elasticity showed an adequate reliability with the tortilla briquet shape (0.94). The evaluated parameters with the texture meter and the sample shape type briquet, showed a high reliability degree what makes possible the comparison of maize tortilla texture data.     

Utilization and transport of acetic acid in Dekkera anomala and their implications on the survival of the yeast in acidic environments

The yeast Dekkera anomala IGC 5153 exhibited a restricted ability to use weak acids as the only carbon and energy sources. Of the monocarboxylic, dicarboxylic, and tricarboxylic acids tested, only acetic acid was used in such a way. The cells were able to grow at acetic acid concentrations of 0.1 to 3% (vol/vol) over a pH range of 3.5 to 5.5, and the specific growth rates decreased exponentially with the increase of the undissociated acetic acid concentration in the culture medium. Transport assays carried out in cells that exhibited higher specific growth rates showed the presence of an acetate-proton symport associated with a simple diffusion component of the undissociated acetic acid, the weight of the latter increasing with the undissociated acid concentration in the culture media. The acetate carrier was shared by propionic, formic, and sorbic acids and was inducible and repressed by glucose and concentrations of undissociated acetic acid in the culture medium above 0.3% (vol/vol). In undissociated acetic acid repression conditions, the lowest values for the yeast specific growth rates were obtained, and the simple diffusion of the undissociated acid was the only mechanism involved in the acetic acid uptake by the cells. The results will be discussed in terms of the high tolerance of D. anomala to the acidic stress conditions present in wine.     

Quantitative analysis of myofilament protein phosphorylation in small cardiac biopsies

Phosphorylation of cardiac myofilament proteins represents one of the main post‐translational mechanisms that regulate cardiac pump function. Human studies are often limited by the amount of available tissue as biopsies taken during cardiac catheterization weigh only 1 mg (dry weight). Similarly, investigation of time‐ (or dose‐) dependent changes in protein phosphorylation in animal studies is often hampered by tissue availability. The present study describes quantitative analysis of phosphorylation status of multiple myofilament proteins by 2‐DE and Pro‐Q® Diamond stained gradient gels using minor amounts (?0.5 mg dry weight) of human and pig cardiac tissue.     

Deactivation of ferrierite during the skeletal isomerization of linear butenes

Deactivation of ferrierite during the skeletal isomerization of 1-butene at atmospheric pressure and 0.15 atm 1-butene partial pressure was studied. At 300°C, the carbon content shows a sharp increase during the first 30 min-on-stream, with a slower growth thereafter. Temperature-programmed oxidation profiles corresponding to different times-on-stream are similar, showing two well-defined combustion peaks centered at about 325 and 640°C, respectively. When starting the 1-butene feed with the catalytic bed at 100 or 200°C and then increasing the temperature up to 300°C, no significant difference is observed, neither in carbon content nor in oxidation profiles. Important differences in the profiles are observed by comparing at the same time at each temperature. The lower the temperature, the higher the reactivity toward oxidation at low temperature. The carbonaceous deposit formed at 100°C shows the main combustion peak at the lowest temperature (135°C) and a more olefinic character; it could be related to a strong adsorption of reactant molecules. At 200°C, the proportion of saturated species associated to oligomers increases; while at 300°C, coke shows both aromatic and olefinic species.     

Overproduction of bovine {beta}-casein in Escherichia coli and engineering of its main chymosin cleavage site

A cDNA clone containing the entire coding region for bovineß-casein A³ flanked by 53 base pairs of 5' non-codingand 358 base pairs of 3' non-coding sequences was isolated froma bovine mammary cDNA phagemid library. The coding segment formature ß-casein was subcloned into the T7 expressionsystem, in which the expression of recombinant ß-caseinwas controlled by the T7 gene 10 promoter and ribosome bindingsite. High level expression of Met-ß-casein to 20%of the total soluble proteins was obtained in Escherichia coliwithin 2 h after induction of T7 RNA-polymerase synthesis. Inan attempt to induce secretion the coding segment for matureß-casein was coupled to the ompA translations initiationsignal and signal peptide coding sequence but no secretion ofthe fusion protein and no processing of the signal peptide fromthe fusion protein was observed. Instead, the Met-ß-caseincould be isolated in asoluble form from E.coli cells after anosmotic shock, indicative of a periplasmic location. This proceduredid not lyse the cells. The protein was purified to homogeneityafter a pH 4.8 isoelectric precipitation followed by reversed-phasehigh-performance liquid chromatography. The ß-caseincDNA was altered to change the main chymosin cleavage siteinß-casein at position 192–193 in two ways, namelyfrom Leu–Tyr to Pro–Pro and to Leu–stop. Thesemutations were designed to prevent generation of the bitterpeptide ßcasein(193–209) by chymosin cleavage.The mutant Met-ß-caseins were expressed in E.colito the same level as wild-type Met-ß-casein. Purifiedmutant Met-ß-casein(Prol92– Prol93) was no longerhydrolysed by chymosin at the 192–193 bond.     

Optimization of platinum dispersion in Pt–PEM electrodes: application to the electrooxidation of ethanol

Nafion® can be used as a solid polymer electrolyte in a PEM fuel cell. Direct platinization of the membrane was realized by chemical reduction of a platinum compound. The platinization procedure was modified to enhance the roughness factor and thus to improve the electrocatalytic activity towards ethanol electrooxidation. The Pt–PEM electrodes were characterized by TEM, atomic absorption analysis, cyclic voltammetry and their polarization curves for ethanol electrooxidation.     

The Effect of Future Climate Perturbations on N<Subscript>2</Subscript>O Emissions from a Fertilized Humid Grassland

N₂O emissions from a fertilized humid grassland near Cork, Ireland were continuously measured during 2003 using an eddy covariance system. For most of the year emissions were close to zero and 60% of the emissions occurred in eight major events of 2–20 days’ duration. Two hundred and seven kg ha⁻¹ of synthetic N and 130 kg ha⁻¹ organic N were applied over the year and the total measured annual N₂O emission was 11.6 kg N ha⁻¹. The flux data were used to test the prediction of N₂O emissions by the DNDC (DeNitrification – DeComposition) model. The model predicted total emissions of 15.4 kg N ha⁻¹, 32 % more than the observed emissions. On this basis the model was further used to simulate (a) background (non-anthropogenic) N₂O emissions and (b) the effect on N₂O emissions of future climate perturbations based on the Hadley Center model output of the IS92a scenario for Ireland. DNDC predicts 1.7 kg N ha⁻¹ year⁻¹ of background N₂O emissions, accounting for 15% of the observed emissions. Climate shifts will increase total annual modeled N₂O emissions from 15.4 kg N ha⁻¹ to 22.4 kg N ha⁻¹ if current levels of N applications are maintained, or to 21.2 kg N ha⁻¹ if synthetic N applications are reduced to 170 kg N ha⁻¹ to comply with recent EU water quality legislation. Thus the projected increase in N₂O emissions due to climate change is far larger than the decrease expected from reduced fertilizer applications.