bluuebunny/crossref_metadata_2025_split huggingface dataset:
Toxicological Evaluation of the Hexadecanoic Acid and β Sitosterol for Daphnia similis Claus, 1876 (Cladoceran, Crustacean)
Authors: Sobreira Romena Galvani , Heid-Furley T. , Effigen J. I. , Oliveira-Filho A. C. de 
Published: March 2010

The wood used as raw material by cellulose and paper factories has high levels of extractives with high toxic potential, such as fatty acids and the phytosterol β sitosterol, which promote toxic effects (masculinization of females, among others) in aquariums such as fish and invertebrates. Due to the growing concern about the environment in Brazil, factories such as Aracruz Celulose S.A. routinely carry out ecotoxicological tests to evaluate the effects of their effluents on the environment and anticipate possible environmental problems. The present study was carried out in two stages with the objective of relating the toxicity of the mixed effluent from Aracruz Celulose with some of the reference extractives. The first stage consisted of identifying and quantifying fatty acids and β-sitosterol present in sectoral effluents through chromatographic analysis. In the second stage, ecotoxicological analyzes were carried out with two of the most abundant extractives and with the mixed (untreated) effluent, to assess whether the acute toxicity of this effluent for the organism Daphnia similis is related to the current concentrations of the extractives tested. The quantification of extractives present in Aracruz Celulose's sectoral effluents showed that effluents from purification, acid bleaching and evaporation developed with the highest concentrations of these compounds, while effluents from the wood yard and alkaline bleaching developed with the lowest values. Linoleic, hexadecanoic, hexacosanoic, octadecenoic and docosanoic fatty acids were the most abundant, and β sitosterol was identified in all effluents analyzed, being in higher concentration in the purification effluent. The chosen extractives did not present acute toxicity to test organisms, even at concentrations ten times greater than those present in Aracruz Celulose's sectoral effluents, however, the results of the three mixed effluent toxicity tests for D. similis showed acute toxicity, with EC50 equal to 16.66%, 23.62% and 52.02%.
Stochastic Differential Equations with Jumps: Simulation
Authors: Bruti‐Liberati Nicola , Platen Eckhard 
Published: March 2010

Abstract
In finance and economics the key dynamics are often specified via stochastic differential equations (SDEs) of jump‐diffusion type. The class of jump‐diffusion SDEs that admits explicit solutions is rather limited. In this paper we give a brief overview on strong and weak discrete time approximations for solutions of SDEs with jumps.
Combustion Fundamentals
Authors: Janbozorgi Mohammad , Far Kian Eisazadeh , Metghalchi Hameed 
Published: March 2010

Abstract
The sections in this article are

Introduction

Combustion Thermodynamics

Enthalpy of Reaction

Flame Temperature

Chemical Equilibrium

Chemical Kinetics

Combustion Chemical Reactions

Kinetic Rate Equations

Chemical Time Scales and Nonequilibrium Effects

Kinetics Simplification and Reduction

Rate‐Controlled Constrained‐Equilibrium (
RCCE
) Method

Laminar Premixed Flames

Governing Equations

Experimental Approach

Laminar Burning Speed Measurement Techniques

Diffusion Flames

Conclusions
Recent Advances in the Study of Structural Materials Compatibility with Hydrogen
Authors: Dadfarnia M. , Novak P. , Ahn D. C. , Liu J. B. , Sofronis P. , Johnson D. D. , Robertson I. M. 
Published: March 2010

AbstractHydrogen is a ubiquitous element that enters materials from many different sources. It almost always has a deleterious effect on mechanical properties. In non‐hydride‐forming systems, research to date has identified hydrogen‐enhanced localized plasticity and hydrogen‐induced decohesion as two viable mechanisms for embrittlement. However, a fracture prediction methodology that associates macroscopic parameters with the degradation mechanisms at the microscale has not been established, as of yet. In this article, we report recent work on modeling and simulation of hydrogen‐induced crack initiation and growth. Our goal is to develop methodologies to relate characteristics of the degradation mechanisms from microscopic observations and first‐principles calculations with macroscopic indices of embrittlement. The approach we use involves finite element analysis of the coupled hydrogen transport problem with hydrogen‐assisted elastoplastic deformation, thermodynamic theories of decohesion, and ab initio density functional theory calculations of the hydrogen effect on grain boundaries.
Copper(II) Bromide/Boron Trifluoride Etherate‐Cocatalyzed Cyclization of Ketene Dithioacetals and p‐Quinones: a Mild and General Approach to Polyfunctionalized Benzofurans
Authors: Liu Yingjie , Wang Mang , Yuan Hongjuan , Liu Qun 
Published: March 2010

AbstractA new application of copper(II) bromide‐activated ketene dithioacetals as nucleophiles in organic chemistry has been developed. Under the cocatalysis of copper(II) bromide (2.0 mol%) and boron trifluoride etherate (10 mol%), the conjugate addition and sequential cyclization of α‐electron‐withdrawing group‐substituted ketene dithioacetals with p‐quinones in acetonitrile at room temperature gave a variety of benzofurans. This formal [3+2] cycloaddition provides a general method for catalytic synthesis of polyfunctionalized benzofurans with the advantages of readily available starting materials, cheap catalysts, mild reaction conditions, good yields and wide range of synthetic potential for the benzofuran products. Further transformations of the resulting benzofurans to 2‐aminobenzofurans and benzofuro[2,3‐d]pyrimidine derivatives are also investigated.
Silver‐Catalyzed Aldehyde Olefination Using Siloxyalkynes
Authors: Sun Jianwei , Keller Valerie A. , Meyer S. Todd , Kozmin Sergey A. 
Published: March 2010

AbstractWe describe the development of a silver‐catalyzed carbonyl olefination employing electron‐rich siloxyalkynes. This process constitutes an efficient synthesis of trisubstituted unsaturated esters, and represents an alternative to the widely utilized Horner–Wadsworth–Emmons reaction. Excellent diastereoselectivities are observed for a range of aldehydes using either 1‐siloxy‐1‐propyne or 1‐siloxy‐1‐hexyne. This mild catalytic process also enables chemoselective olefination of aldehydes in the presence of either ester or ketone functionality. Furthermore, since no by‐products are generated, this catalytic process is perfectly suited for development of sequential reactions that can be carried out in a single flask.
A Simple, Effective Boron‐Halide Ethoxylation Catalyst
Authors: Moloy Kenneth G. 
Published: March 2010

AbstractBoron esters B(OR)3, readily derived from boric acid and alcohols, combine with iodide or bromide to catalyze the ethoxylation of alcohols and phenols, giving good rates and narrow product distributions. The combined action of a weak electrophile [B(OR)3] and a weak nucleophile (halide) allows for the ethoxylation of base‐sensitive alcohols. Experiment suggests a new mechanism for this commercially important reaction proceeding through key β‐haloalkoxy intermediates.
Microbial systems engineering: First successes and the way ahead
Authors: Dietz Sven , Panke Sven 
Published: March 2010

AbstractThe first promising results from “streamlined,” minimal genomes tend to support the notion that these are a useful tool in biological systems engineering. However, compared with the speed with which genomic microbial sequencing has provided us with a wealth of data to study biological functions, it is a slow process. So far only a few projects have emerged whose synthetic ambition even remotely matches our analytic capabilities. Here, we survey current technologies converging into a future ability to engineer large‐scale biological systems. We argue that the underlying synthetic technology, de novo DNA synthesis, is already rather mature – in particular relative to the scope of our current synthetic ambitions. Furthermore, technologies towards rationalizing the design of the newly synthesized DNA fragment are emerging. These include techniques to implement complex regulatory circuits, suites of parts on a DNA and RNA level to fine tune gene expression, and supporting computational tools. As such DNA fragments will, in most cases, be destined for operating in a cellular context, attention has to be paid to the potential interactions of the host with the functions encoded on the engineered DNA fragment. Here, the need of biological systems engineering to deal with a robust and predictable bacterial host coincides with current scientific efforts to theoretically and experimentally explore minimal bacterial genomes.
Heat Effects upon Electrochemical Copper Deposition on Polycrystalline Gold
Authors: Etzel Kai D. , Bickel Katrin R. , Schuster Rolf 
Published: March 2010

AbstractHeat effects upon Cu deposition on polycrystalline Au surfaces from sulphuric acid electrolytes were calorimetrically measured. By combination of pyroelectric temperature detection at the backside of a thin electrode foil with pulsed electrochemistry, sensitivities to electrochemical conversions of a few percent of a Cu monolayer (ML), corresponding to about 1 μJ cm−2 were achieved. We compared the heat evolution upon Cu under potential deposition (UPD), Cu deposition onto a fully developed Cu UPD layer and bulk Cu deposition onto a 300 ML thick Cu layer on Au. The heat effects were measured dependent on the amplitudes of the applied potential steps, that is, the driving forces of the respective reactions. From the differences of the heat effects among the Cu deposition processes, we deduced implications on the reaction mechanisms. For Cu UPD, the heat effects were explicable by the deposition of 1.3 Cu atoms per two electrons flowing to the electrode accompanied by sulphate coadsorption, similar to Cu UPD from sulphuric acid solutions on Au(111). Upon Cu deposition on a Cu UPD layer the heat effects signal considerable anion coadsorption up to the deposition of about 0.5 ML of Cu. At higher conversions the deposition mechanism gradually changes towards bulk Cu deposition, accompanied by reduction of the sulphate coverage.
Cooperative spectrum sensing with imperfect feedback channel in the cognitive radio systems
Authors: Oh Dong‐Chan , Lee Yong‐Hwan 
Published: March 2010

AbstractThe primary object of cognitive radio is to increase spectral efficiency, while causing limited interference to primary users who are using the spectrum. Hence, an essential part of cognitive radio is a spectrum sensing that determines whether a particular spectrum is occupied or not by a primary user. However, the sensing decision of a local secondary user alone may not be reliable enough due to shadowing and multipath fading of wireless channels. Recently, cooperative spectrum sensing has emerged as a remedy to the problems of local sensing. To sense the spectrum in a cooperative manner, secondary users report their local decisions to a cognitive base station through a feedback channel that is subject to fading and shadowing. Therefore, though the local sensing result is obtained accurately, it might not be suitable for making a cooperative decision due to feedback error. To alleviate this problem, we propose a hard decision combining‐based cooperative spectrum sensing scheme in the presence of a feedback error caused by imperfect channel condition. In the proposed scheme, only the most favorable secondary users, those whose reporting channel conditions are peak, are allowed for cooperation. Through the proposed scheme, we can maximize the detection probability while guaranteeing that the desired false alarm probability is maintained. The simulation results show that the proposed scheme provides better spectrum sensing performance than the conventional scheme. Copyright © 2010 John Wiley & Sons, Ltd.
Broadening the Synthetic Scope of the Iron(III)‐Catalyzed Aza‐Prins Cyclization
Authors: Carballo Rubén M. , Valdomir Guillermo , Purino Martín , Martín Víctor S. , Padrón Juan I. 
Published: March 2010

AbstractThe nature and influence of the N‐sulfonyl group in aza‐Prins cyclization and the reactivity of the six‐membered aza‐cycle generated has been studied. The aza‐Prins cyclization of γ,δ‐unsaturated amines with a tosyl group at the nitrogen atom produces 2‐alkyl‐4‐halo‐1‐tosyl‐1,2,5,6‐tetrahydropyridines with a halovinyl function, extraordinarily stable to further derivatization and detosylation conditions. To modulate the reactivity of such aza‐cycles, a general study of the aza‐Prins cyclization reaction was performed with several sulfonamides. Ring formation occurs satisfactorily with both N‐nosyl and N‐mesylamines providing optimal conditions for further synthetic transformations. To exemplify the scope of this methodology, a short synthesis of the alkaloid coniine was successfully carried out.
Comparative Microbial Fuel Cell Evaluations of Shewanella spp.
Authors: Bretschger Orianna , Cheung Andrea C. M. , Mansfeld Florian , Nealson Kenneth H. 
Published: March 2010

AbstractTo date several different strains of Shewanella have been sequenced; however, many of these isolates have not been evaluated in microbial fuel cell (MFC) systems. Here we present a summary of power densities, current densities, cell attachment, and coulombic efficiencies for eight different Shewanella strains in two different MFC configurations. Our results show that different Shewanella strains have unique characteristics as MFC biocatalysts and that strain S. putrefaciens W3‐18‐1 significantly outperforms S. oneidensis MR‐1. Further, these results suggest that Shewanella strain performance in MFCs is strongly impacted by system parameters such as buffer composition and ion exchange membrane selection.
Enzymatic Anodes for Hydrogen Fuel Cells based on Covalent Attachment of Ni‐Fe Hydrogenases and Direct Electron Transfer to SAM‐Modified Gold Electrodes
Authors: Rüdiger Olaf , Gutiérrez‐Sánchez Cristina , Olea David , Pereira Inês A. C. , Vélez Marisela , Fernández Víctor M. , De Lacey Antonio L. 
Published: March 2010

AbstractImmobilization of hydrogenases onto electrodes is of great interest for developing biofuel cells that use H2 as a fuel. In this way, hydrogenases replace Pt as electrocatalyst for oxidizing H2 in the anode. We have developed a method of covalent bonding of Desulfovibrio gigas Ni‐Fe hydrogenase and Desulfovibrio vulgaris Hildenborough Ni‐Fe‐Se hydrogenase to gold electrodes modified with a self assembled monolayer (SAM) of 4‐aminothiophenol for measuring high electrocatalytic currents of H2‐oxidation in the absence of redox mediators. Electrochemical measurements and atomic force microscopy characterization show that direct electron transfer between enzyme and the Au support is due to formation of an organized monolayer of hydrogenase over the SAM‐modified surface.
Development of a Chitosan Scaffold Electrode for Fuel Cell Applications
Authors: Lau Carolin , Martin Georgianna , Minteer Shelley D. , Cooney Michael J. 
Published: March 2010

AbstractHydrophobically modified chitosan has been proposed for enzyme immobilization and stabilization at bioelectrodes in biofuel cells. In this paper, we analytically evaluate the attributes of employing hydrophobically modified chitosan molded into high porosity scaffolds to improve enzyme activity and mass transport of malate dehydrogenase bioelectrodes. Results suggest that the hydrophobically modified chitosan can alter catalytic activity of malate dehydrogenase and that scaffold structure improves power density over chitosan thin films. Fluorescence measurements are also presented that correlate the improved activity to alterations in the amphiphilic nature of the chemical microenvironment (immediately surrounding the enzyme) that the modified chitosan affords. Commentary is also given on how mass transport through the chitosan matrix can be improved in order to achieve higher power densities.
The Role of Shewanella oneidensis MR‐1 Outer Surface Structures in Extracellular Electron Transfer
Authors: Bouhenni Rachida A. , Vora Gary J. , Biffinger Justin C. , Shirodkar Sheetal , Brockman Ken , Ray Ricky , Wu Peter , Johnson Brandy J. , Biddle Eulandria M. , Marshall Matthew J. , Fitzgerald Lisa A. , Little Brenda J. , Fredrickson Jim K. , Beliaev Alexander S. , Ringeisen Bradley R. , Saffarini Daad A. 
Published: March 2010

AbstractThe ability of the metal reducer Shewanella oneidensis MR‐1 to generate electricity in microbial fuel cells (MFCs) depends on the activity of a predicted type IV prepilin peptidase; PilD. Analysis of an S. oneidensis MR‐1 pilD mutant indicated that it was deficient in pili production (Msh and type IV) and type II secretion (T2S). The requirement for T2S in metal reduction has been previously identified, but the role of pili remains largely unexplored. To define the role of type IV or Msh pili in electron transfer, mutants that lack one or both pilus biogenesis systems were generated and analyzed; a mutant that lacked flagella was also constructed and tested. All mutants were able to reduce insoluble Fe(III) and to generate current in MFCs, in contrast to the T2S mutant that is deficient in both processes. Our results show that loss of metal reduction in a PilD mutant is due to a T2S deficiency, and therefore the absence of c cytochromes from the outer surface of MR‐1 cells, and not the loss of pili or flagella. Furthermore, MR‐1 mutants deficient in type IV pili or flagella generated more current than the wild type, even though extracellular riboflavin levels were similar in all strains. This enhanced current generating ability is in contrast to a mutant that lacks the outer membrane c cytochromes, MtrC and OmcA. This mutant generated significantly less current than the wild type in an MFC and was unable to reduce Fe(III). These results indicated that although nanofilaments and soluble mediators may play a role in electron transfer, surface exposure of outer membrane c cytochromes was the determining factor in extracellular electron transfer in S. oneidensis MR‐1.
An L‐Lactate Amperometric Enzyme Electrode Based on L‐Lactate Oxidase Immobilized in a Laponite Gel on a Glassy Carbon Electrode. Application to Dairy Products and Red Wine
Authors: Zanini Veronica Paz , de Mishima Beatriz López , Labbé Pierre , Solís Velia 
Published: March 2010

AbstractA biosensor based on the immobilization of Lactate oxidase in laponite–organosilasesquioxane films on glassy carbon electrode for the quantification of L‐lactate in wine and dairy products is presented. The bioelectrode showed a very high sensitivity (0.33±0.01) A cm−2 M−1 and a short time response (10 s) for less than 1 U of enzyme. No significant interferences, including ascorbic acid, were detected. For red wine, matrix effects assigned to polyphenols and anthocyanins were observed, which ware easily overcome by sample dilution. Our L‐lactate determinations were in good agreement with those of two standard methods.
Self‐Assembly of Gold Nanoparticles/Electroactive Polyelectrolyte Multilayer Films for Tunable Electrocatalysis
Authors: Liu Xiaoqing , Wang Fuan , Han Shuang , Shi Lihong , Xu Guobao 
Published: March 2010

AbstractThis study described fabrication, characterization, and application of multilayer films based on layer‐by‐layer assembly of ferrocene poly(ethylenimine) and gold nanoparticles. Assembly process of the multilayer film was investigated by atomic force microscopy, UV‐visible absorption spectroscopy and electrochemical impedance spectroscopy. The multilayer films exhibited a pair of well‐defined redox peaks as revealed by cyclic voltammetry, as well as bifunctional and fine‐tunable electrocatalysis for oxidation of ascorbic acid and reduction of oxygen. Both the outer layer and layer number had effect on the electrocatalytic response. Electrocatalytic activity of the films could be controlled with assemblies at the nanoscale level by simply adjusting deposition cycles or amount of component in the films.
Simultaneous Determination of Dihydroxybenzene Isomers at MWCNTs/β‐Cyclodextrin Modified Carbon Ionic Liquid Electrode in the Presence of Cetylpyridinium Bromide
Authors: Yu Qiong , Liu Yong , Liu Xiaoying , Zeng Xiandong , Luo Shenglian , Wei Wanzhi 
Published: March 2010

AbstractSimultaneous determination of dihydroxybenzene isomers was investigated at a multi‐wall carbon nanotubes (MWCNTs)/β‐cyclodextrin composite modified carbon ionic liquid electrode in phosphate buffer solution (pH 7.0, 1/15 mol/L) in the presence of cationic surfactant cetylpyridinium bromide (CPB). With the great enhancement of surfactant CPB, the voltammetric responses of dihydroxybenzene isomers were more sensitive and selective. The oxidation peak potential of hydroquinone was about 0.024 V, catechol was about 0.140 V and resorcinol 0.520 V in differential pulse voltammetric (DPV) measurements, which indicated that the dihydroxybenzene isomers could be separated entirely. The electrode showed wide linear behaviors in the range of 1.2×10−7–2.2×10−3, 7.0×10−7–1.0×10−3, 2.6×10−6–9.0×10−4 mol/L for hydroquinone, catechol and resorcinol, respectively. And the detection limits of the three dihydroxybenzene isomers were 4.0×10−8, 8.0×10−8, 9.0×10−7 mol/L, respectively. The proposed method could be applied to the determination of dihydroxybenzene isomers in artificial wastewater, and the recovery was from 97.4% to 104.2%.
Delta2D and Proteomweaver: Performance evaluation of two different approaches for 2‐DE analysis
Authors: Millioni Renato , Miuzzo Manuela , Sbrignadello Stefano , Murphy Ellen , Puricelli Lucia , Tura Andrea , Bertacco Elisa , Rattazzi Marcello , Iori Elisabetta , Tessari Paolo 
Published: March 2010

Abstract2‐DE is a fundamental technology used in proteomics research. However, despite its high capacity to simultaneously separate several proteins for subsequent identification and quantitative comparison studies, a drawback for this technique is its limited reproducibility, especially when comparing data from different laboratories. 2‐DE‐related variability can be broadly divided into two categories: experimental and post‐experimental. Experimental variability depends on physical and chemical parameters, whereas post‐experimental variability arises when gels are analyzed by different software packages, particularly when different workflows are followed. In this paper, we compared the analysis performance of two software packages, Delta2D and Proteomweaver, using both standard and experimental gel images. Using standard gel images, the false negative spot count was 50% lower, the false positive count was 77% lower, the true positive count was 19% higher and spot matching was 4% higher in Delta2D when compared to Proteomeweaver. Using experimental gel images, we found that the total amount of time taken to complete the analysis with Delta2D was 30% that of the time needed with Proteomweaver and required fewer user interventions. The differences between ease of use and workflow strategy of these programs is discussed.