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Reduction Potential (reduction + potential)
Selected AbstractsReactivity in the Upper Limits of the Reduction Potential in Solution: Arene Dianion Intermolecular Carbolithiation of Alkenes.CHEMINFORM, Issue 48 2006Cristobal Melero Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] A New Method of Carbon-Nanotube Patterning Using Reduction PotentialsADVANCED MATERIALS, Issue 12 2009Jong Hak Lee Noble metals promote the oxidation of carbon nanotubes (CNTs) at the relatively low temperature of 350,°C. The reduction potential of multiwalled CNTs is located between those of W and Ni, while that of single-walled CNTs is between those of Ni and In. Nanometer-sized patterns on CNT films were successfully fabricated using differences in reduction potential between the CNTs and noble metals. [source] Quantum Chemical Calculations of Reduction Potentials of AnO2+2/AnO+2 (An: U, Np, Pu, Am) and Fe3+/Fe2+ Couples.CHEMINFORM, Issue 40 2006Satoru Tsushima Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Reactivities of acridine compounds in hydride transfer reactionsJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 7 2007In-Sook Han Lee Abstract Reactivities of acridine derivatives (10-benzylacridinium ion, 1a+, 10-methylacridinium ion, 1b+, and 10-methyl-9-phenylacridinium ion, 1c+) have been compared quantitatively for hydride transfer reactions with 1,3-dimethyl-2-substituted phenylbenzimidazoline compounds, 2Ha,h. Reactions were monitored spectrophotometrically in a solvent consisting of four parts of 2-propanol to one part of water by volume at 25,±,0.1,°C. Reduction potentials have been estimated for acridine derivatives by assuming that the equilibrium constants for the reductions of 1a+,c+ by 2Hb would be the same in aqueous solution and accepting ,361,mV as the reduction potential of the 1-benzyl-3-carbamoylpyridinium ion. The resulting reduction potentials, E, are ,47,mV for 1a+, ,79,mV for 1b+, and ,86,mV for 1c+. Each of acridine derivatives gives a linear Brønsted plot for hydride transfer reactions. The experimental slopes were compared with those obtained by Marcus theory. This comparison shows that the kinetic data are consistent with a one-step mechanism involving no high-energy intermediates. Copyright © 2007 John Wiley & Sons, Ltd. [source] Nanoscaled Polyaniline Fibers Prepared by Ferric Chloride as an OxidantMACROMOLECULAR RAPID COMMUNICATIONS, Issue 5 2006Lijuan Zhang Abstract Summary: Nanoscaled polyaniline (PANI) fibers with 17,30 nm in diameter were successfully prepared by oxidation polymerization using ferric hydrochloride (FeCl3,·,6H2O) as an oxidant in the presence of p -toluenesulfonic acid (p -TSA), , -naphthalenesulfonic acid (, -NSA), and camphorsulfonic acid (CSA) as the dopants. The resulting nanofibers show smaller diameter, higher crystallinity and conductivity (10,1 S,·,cm,1) compared with the nanofibers oxidized by ammonium persulfate (APS), which may be due to the lower oxidation/reduction potential of FeCl3. SEM images of the PANI nanofibers prepared by oxidation polymerization using ferric hydrochloride as an oxidant. [source] Bioelectrocatalysis of Oxygen Reduction Reaction by Laccase on Gold ElectrodesELECTROANALYSIS, Issue 13-14 2004Gautam Gupta Abstract Direct electron transfer (DET) reaction of oxygen electroreduction catalyzed by enzyme laccase on monolayer modified gold electrodes was studied. Three different monolayers were investigated, from which 4-aminothiophenol was found to be optimal for the direct electron transfer to take place. The electrocatalytic reduction of the oxygen at the electrode surface was found to depend significantly on the method of immobilization. Fungal laccase from Coriolus hirsitus modified with sodium-periodate demonstrated more anodic onset potential for oxygen reduction than the tree laccase from Rhus vernicifera. Physical immobilization of enzyme did not result in any manifestation of bioelectrocatalytic activity. A maximum anodic shift in reduction potential of 300,mV was observed for fungal laccase covalently coupled on the electrode surface. [source] Voltammetric Study of Nitro Radical Anion Generated from Some Nitrofuran Compounds of Pharmacological SignificanceELECTROANALYSIS, Issue 1 2003S. Bollo Abstract The electrochemical behavior of 2-(5-amino- 1,3,4-oxadiazolyl)-5-nitrofuran (NF359) and its comparison with well-known drugs such as nifurtimox (NFX) and nitrofurazone (NFZ) in protic, mixed and aprotic media by cyclic voltammetry, tast and differential pulse polarography was studied. All the compounds were electrochemically reducible in all media being the reduction of the nitrofuran group the main voltammetric signal. The one-electron reduction couple due to the nitro radical anion formation was visualized in mixed (for NF359 and NFZ) and aprotic media (for all compounds). By applying a cyclic voltammetric methodology we have calculated the decay constants (k2) of the corresponding nitro radical anions in mixed and aprotic media. In mixed medium data fit well with a disproportionation reaction of the nitro radical anion but in aprotic medium fit better with a dimerization reaction. Also, considering cyclic voltammetric measurements in aprotic media we have estimated the reduction potential of the RNO2/RNO2., couple in aqueous medium, pH 7 (E17 values) finding very good correlation with E17 values obtained by pulse radiolysis. Furthermore we have calculated the equilibrium constants from the electron transfer from nitro radical anion to oxygen (kO2) finding that nitro radical anion from NF359 is thermodynamically favored to react with oxygen in respect to both NFZ and NFX. [source] Ex Ante Hedging Effectiveness of UK Stock Index Futures Contracts: Evidence for the FTSE 100 and FTSE Mid 250 ContractsEUROPEAN FINANCIAL MANAGEMENT, Issue 4 2000Darren Butterworth Ex ante hedging effectiveness of the FTSE 100 and FTSE Mid 250 index futures contracts is examined for a range of portfolios, consisting of stock market indexes and professionally managed portfolios (investment trust companies). Previous studies which focused on ex post hedging performance using spot portfolios that mirror market indexes are shown to overstate the risk reduction potential of index futures. Although ex ante hedge ratios are found to be characterised by intertemporal instability, ex ante hedging performance of direct hedges and cross hedges approaches that of the ex post benchmark when hedge ratios are estimated using a sufficient window size. [source] Insights into the design of a hybrid system between Anabaena ferredoxin-NADP+ reductase and bovine adrenodoxinFEBS JOURNAL, Issue 4 2003Merche Faro The opportunity to design enzymatic systems is becoming more feasible due to detailed knowledge of the structure of many proteins. As a first step, investigations have aimed to redesign already existing systems, so that they can perform a function different from the one for which they were synthesized. We have investigated the interaction of electron transfer proteins from different systems in order to check the possibility of heterologous reconstitution among members of different chains. Here, it is shown that ferredoxin-NADP+ reductase from Anabaena and adrenodoxin from bovine adrenal glands are able to form optimal complexes for thermodynamically favoured electron transfer reactions. Thus, electron transfer from ferredoxin-NADP+ reductase to adrenodoxin seems to proceed through the formation of at least two different complexes, whereas electron transfer from adrenodoxin to ferredoxin-NADP+ reductase does not take place due because it is a thermodynamically nonfavoured process. Moreover, by using a truncated adrenodoxin form (with decreased reduction potential as compared with the wild-type) ferredoxin-NADP+ reductase is reduced. Finally, these reactions have also been studied using several ferredoxin-NADP+ reductase mutants at positions crucial for interaction with its physiological partner, ferredoxin. The effects observed in their reactions with adrenodoxin do not correlate with those reported for their reactions with ferredoxin. In summary, our data indicate that although electron transfer can be achieved in this hybrid system, the electron transfer processes observed are much slower than within the physiological partners, pointing to a low specificity in the interaction surfaces of the proteins in the hybrid complexes. [source] Redox properties of the couple compound I/native enzyme of myeloperoxidase and eosinophil peroxidaseFEBS JOURNAL, Issue 19 2001Jürgen Arnhold The standard reduction potential of the redox couple compound I/native enzyme has been determined for human myeloperoxidase (MPO) and eosinophil peroxidase (EPO) at pH 7.0 and 25 °C. This was achieved by rapid mixing of peroxidases with either hydrogen peroxide or hypochlorous acid and measuring spectrophotometrically concentrations of the reacting species and products at equilibrium. By using hydrogen peroxide, the standard reduction potential at pH 7.0 and 25 °C was 1.16 ± 0.01 V for MPO and 1.10 ± 0.01 V for EPO, independently of the concentration of hydrogen peroxide and peroxidases. In the case of hypochlorous acid, standard reduction potentials were dependent on the hypochlorous acid concentration used. They ranged from 1.16 V at low hypochlorous acid to 1.09 V at higher hypochlorous acid for MPO and from 1.10 V to 1.03 V for EPO. Thus, consistent results for the standard reduction potentials of redox couple compound I/native enzyme of both peroxidases were obtained with all hydrogen peroxide and at low hypochlorous acid concentrations: possible reasons for the deviation at higher concentrations of hypochlorous acid are discussed. They include instability of hypochlorous acid, reactions of hypochlorous acid with different amino-acid side chains in peroxidases as well as the appearance of a compound I,chloride complex. [source] Urban Form and Household Activity-Travel BehaviorGROWTH AND CHANGE, Issue 2 2006RON N. BULIUNG ABSTRACT Cities and metropolitan regions face several challenges including urban sprawl, auto dependence and congestion, and related environmental and human health effects. Examining the spatial characteristics of daily household activity-travel behavior holds important implications for understanding and addressing urban transportation issues. Research of this sort can inform development of urban land use policy that encourages the use of local opportunities, potentially leading to reduced motorized travel. This article examines the potential household activity-travel response to a planned metropolitan polycentric hierarchy of activity centers. Behavioral observations have been drawn from an activity-travel survey conducted in the Portland, Oregon, metropolitan area during the mid-1990s. Evidence presented from exploratory analysis indicates an urban/suburban differential, with less daily travel and smaller activity spaces for urban households. Investigation of the travel reduction potential of the proposed land-use strategy suggests that location effects could be offset by adjustments to household sociodemographic and mobility characteristics. [source] A New Method of Carbon-Nanotube Patterning Using Reduction PotentialsADVANCED MATERIALS, Issue 12 2009Jong Hak Lee Noble metals promote the oxidation of carbon nanotubes (CNTs) at the relatively low temperature of 350,°C. The reduction potential of multiwalled CNTs is located between those of W and Ni, while that of single-walled CNTs is between those of Ni and In. Nanometer-sized patterns on CNT films were successfully fabricated using differences in reduction potential between the CNTs and noble metals. [source] Implications of system expansion for the assessment of well-to-wheel CO2 emissions from biomass-based transportationINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 13 2010Elisabeth Wetterlund Abstract In this paper we show the effects of expanding the system when evaluating well-to-wheel (WTW) CO2 emissions for biomass-based transportation, to include the systems surrounding the biomass conversion system. Four different cases are considered: DME via black liquor gasification (BLG), methanol via gasification of solid biomass, lignocellulosic ethanol and electricity from a biomass integrated gasification combined cycle (BIGCC) used in a battery-powered electric vehicle (BPEV). All four cases are considered with as well as without carbon capture and storage (CCS). System expansion is used consistently for all flows. The results are compared with results from a conventional WTW study that only uses system expansion for certain co-product flows. It is shown that when expanding the system, biomass-based transportation does not necessarily contribute to decreased CO2 emissions and the results from this study in general indicate considerably lower CO2 mitigation potential than do the results from the conventional study used for comparison. It is shown that of particular importance are assumptions regarding future biomass use, as by expanding the system, future competition for biomass feedstock can be taken into account by assuming an alternative biomass usage. Assumptions regarding other surrounding systems, such as the transportation and the electricity systems are also shown to be of significance. Of the four studied cases without CCS, BIGCC with the electricity used in a BPEV is the only case that consistently shows a potential for CO2 reduction when alternative use of biomass is considered. Inclusion of CCS is not a guarantee for achieving CO2 reduction, and in general the system effects are equivalent or larger than the effects of CCS. DME from BLG generally shows the highest CO2 emission reduction potential for the biofuel cases. However, neither of these options for biomass-based transportation can alone meet the needs of the transport sector. Therefore, a broader palette of solutions, including different production routes, different fuels and possibly also CCS, will be needed. Copyright © 2009 John Wiley & Sons, Ltd. [source] Greenhouse gas reduction potential of advanced traffic controlJOURNAL OF ADVANCED TRANSPORTATION, Issue 3 2000Abdulkader Alkadry Reducing greenhouse gas (GHG) emissions from transportation in the context of the climate change issue and the associated Kyoto Agreement of 1997 is a challenge. Since urban transportation is a major contributor to greenhouse gases, measures are required to reduce these emissions. Given that during peak periods, road vehicles propelled by petroleum fuel-based internal combustion engines produce a high level of GHG emissions due to stop and go operations, measures to improve traffic flow can play an effective mitigation role. This paper describes a simulation-based methodology and a case study for the quantification of GHG emission reduction owing to advanced traffic control systems. [source] Premature Salmonella Typhimurium growth inhibition in competition with other Gram-negative organisms is redox potential regulated via RpoS inductionJOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2004E. Komitopoulou Abstract Aims:, To identify the role of oxidation,reduction (redox) potential in the premature growth inhibition and RpoS induction in Salmonella serotype Typhimurium in competitive growth experiments. Methods and Results:, Oxidation,reduction potential was measured throughout the growth of a minority population of Salm. Typhimurium in mixed cultures with other Gram-negative and Gram-positive organisms. A lux -based reporter was also used to evaluate RpoS activity in Salm. Typhimurium in competitor studies. In a mixed culture, the multiplication of a minority population of Salm. Typhimurium was inhibited when competing Gram-negative organisms entered the stationary phase. This was not seen when the competing flora was Gram-positive. The change in redox potential during growth in mixed cultures was closely linked to the inhibition of Salm. Typhimurium growth by Gram-negative competitors. An artificially induced drop in redox potential earlier during growth in mixed cultures with Gram-negative organisms reduced the time to RpoS induction in Salm. Typhimurium and thus inhibited its multiplication prematurely. In contrast, RpoS induction and growth inhibition were prevented under high redox potential conditions. Conclusions:, This work shows that the inhibitory activity of competitive organisms can be mediated through their effect on redox potential-regulated RpoS induction. Significance and Impact of the Study:, Redox potential is shown to be an important determinant of Salm. Typhimurium growth, an observation with practical implications both for its control and detection. [source] Ozonation of 1,3,6-naphthalenetrisulfonic acid in presence of heavy metalsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 8 2004M Sánchez-Polo Abstract A study was conducted of the mechanisms by which heavy metals, commonly present in industrial effluents, increase the purification effectiveness of ozone in the removal of organic contaminants of low biodegradability. For this purpose, the ozonation of 1,3,6-naphthalenetrisulfonic acid (NTS) in the presence of Ni(II), Fe(II), Mn(II), Zn(II), Sr(II), Cr(III), Cd(II), Hg(II), and Cu(II) was examined. The presence of small amounts of Mn(II), Fe(II), Ni(II), Zn(II), and Cr(III) was observed in the system, increasing the degradation rate of the NTS and transforming the dissolved organic matter into CO2. The mineralization of the organic matter was highly favored, especially in the first minutes of treatment. The results obtained appear to indicate that the activity of the metals in the NTS ozonation process is related to their reduction potential. Thus, metals susceptible to oxidation by ozone are potential promoters of NTS ozonation. The presence of Fe(II) or Mn(II) during NTS ozonation increased its degradation rate by 79% and 72% respectively. Moreover, the reaction kinetics of metal oxidation with ozone controls the increase in the purification effectiveness of these systems. The presence of radical scavengers (tert -butanol or bicarbonate) in the medium during the promoted ozonation of NTS showed a negative effect on this process, and the NTS degradation rate decreased with an increasing concentration of these inhibitors in the system. These results confirm that the degradation of NTS by ozone in the presence of heavy metals occurs by a radical mechanism. O3/Zn(II) and O3/Fe(II) systems were applied to the decontamination of urban waste waters. The presence of Zn(II) or Fe(II) during the ozonation produced a reduction during the first 5 min of treatment of 20% or 44%, respectively, in the concentration of dissolved organic matter present in the system. These results show that ozonation in the presence of heavy metals is a highly promising system for the purification of waste waters and industrial effluents. Copyright © 2004 Society of Chemical Industry [source] Intramolecular electronic communication in a dimethylaminoazobenzene,fullerene C60 dyad: An experimental and TD-DFT studyJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 6 2010K. Senthil Kumar Abstract An electronically push,pull type dimethylaminoazobenzene,fullerene C60 hybrid was designed and synthesized by tailoring N,N -dimethylaniline as an electron donating auxochrome that intensified charge density on the ,-azonitrogen, and on N -methylfulleropyrrolidine (NMFP) as an electron acceptor at the 4 and 4, positions of the azobenzene moiety, respectively. The absorption and charge transfer behavior of the hybrid donor-bridge-acceptor dyad were studied experimentally and by performing TD-DFT calculations. The TD-DFT predicted charge transfer interactions of the dyad ranging from 747 to 601 nm were experimentally observed in the UV-vis spectra at 721 nm in toluene and dichloromethane. A 149 mV anodic shift in the first reduction potential of the NN group of the dyad in comparison with the model aminoazobenzene derivative further supported the phenomenon. Analysis of the charge transfer band through the orbital picture revealed charge displacement from the n(NN) (nonbonding) and , (NN) type orbitals centered on the donor part to the purely fullerene centered LUMOs and LUMO+n orbitals, delocalized over the entire molecule. The imposed electronic perturbations on the aminoazobenzene moiety upon coupling it with C60 were analyzed by comparing the TD-DFT predicted and experimentally observed electronic transition energies of the dyad with the model compounds, NMFP and (E)-N,N -dimethyl-4-(p-tolyldiazenyl)aniline (AZNME). The n(NN) , ,*(NN) and ,(NN) , ,*(NN) transitions of the dyad were bathochromically shifted with a significant charge transfer character. The shifting of ,(NN) , ,*(NN) excitation energy closer to the n , ,*(NN) in comparison with the model aminoazobenzene emphasized the predominant existence of charge separated quinonoid-like ground state electronic structure. Increasing solvent polarity introduced hyperchromic effect in the ,(NN) , ,*(NN) electronic transition at the expense of transitions involved with benzenic states, and the extent of intensity borrowing was quantified adopting the Gaussian deconvolution method. On a comparative scale, the predicted excitation energies were in reasonable agreement with the observed values, demonstrating the efficiency of TD-DFT in predicting the localized and the charge transfer nature of transitions involved with large electronically asymmetric molecules with HOMO and LUMO centered on different parts of the molecular framework. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010 [source] Effects of E-Commerce on Greenhouse Gas Emissions: A Case Study of Grocery Home Delivery in FinlandJOURNAL OF INDUSTRIAL ECOLOGY, Issue 2 2002Hanne Siikavirta Summary In this article, we present a literature review of the general and environmental effects of e-commerce in various parts of the demand-supply chain. These are further translated into effects on greenhouse gas (GHG) emissions in the food production and consumption system. The literature study revealed many opportunities for e-commerce to reduce GHG emissions in the food production and consumption system. Some possibly negative effects were also identified. Electronic grocery shopping (e-grocery) home delivery service was chosen as the subject of a case study because of its direct and indirect potential for reducing the GHG emissions in the food production and consumption system. GHG emission reduction potential through the implementation of various e-grocery home delivery strategies was quantified. Depending on the home delivery model used, it is possible to reduce the GHG emissions generated by grocery shopping by 18% to 87% compared with the situation in which household members go to the store themselves. We estimate that the maximum theoretical potential of e-grocery home delivery service for reducing the GHG emissions of Finland is roughly 0.3% to 1.3%; however, the current and estimated future market potential is much smaller, because the estimated market share of e-grocery services is only 10% by 2005. Narrowing the gap between the theoretical and the actual potential requires a model that would simultaneously provide additional value to the consumer and be profitable to companies. To be able to achieve significant reductions in GHG emissions, system-level innovations and changes are required. Further research is needed before conclusions can be reached as to whether e-commerce and e-grocery are useful tools in that respect. [source] Synthesis and evaluation of 2-, 4-, 5-substituted nitroimidazole-iminodiacetic acid- 99mTc(CO)3 complexes to target hypoxic tumorsJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 8 2010Madhava B. Mallia Abstract Determination of hypoxia in tumor is an important problem in the clinical management of cancer. Towards this, a series of differently substituted nitroimidazoles, viz. 2-nitro, 4-nitro and 5-nitroimidazole iminodiacetic acid (IDA) derivatives were synthesized and radio-labeled with a [99mTc(CO)3(H2O)3]+ core. The corresponding 185/187Re(CO)3 analogue of 2-nitroimidazole-IDA- 99mTc(CO)3 complex was also prepared and characterized to elucidate the mode of bonding between the ligand and the M(CO)3 core (M=99mTc, 185/187Re). All the three nitroimidazole-IDA- 99mTc(CO)3 complexes could be prepared in over 95% yield determined by HPLC. The three complexes were then evaluated in a suitable animal model bearing tumor. Though the in vivo accumulation of complexes in hypoxic tissue is governed by factors such as lipophilicity, charge, etc., the variation in accumulation in hypoxic tissue, in the present case, could be explained by considering the reported values of single electron reduction potential of the respective nitroimidazoles. Among the three derivatives studied, the 2-nitroimidazole-IDA- 99mTc(CO)3 complex produced the best result followed by the 5-nitroimidazole complex. Copyright © 2010 John Wiley & Sons, Ltd. [source] Reactivities of acridine compounds in hydride transfer reactionsJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 7 2007In-Sook Han Lee Abstract Reactivities of acridine derivatives (10-benzylacridinium ion, 1a+, 10-methylacridinium ion, 1b+, and 10-methyl-9-phenylacridinium ion, 1c+) have been compared quantitatively for hydride transfer reactions with 1,3-dimethyl-2-substituted phenylbenzimidazoline compounds, 2Ha,h. Reactions were monitored spectrophotometrically in a solvent consisting of four parts of 2-propanol to one part of water by volume at 25,±,0.1,°C. Reduction potentials have been estimated for acridine derivatives by assuming that the equilibrium constants for the reductions of 1a+,c+ by 2Hb would be the same in aqueous solution and accepting ,361,mV as the reduction potential of the 1-benzyl-3-carbamoylpyridinium ion. The resulting reduction potentials, E, are ,47,mV for 1a+, ,79,mV for 1b+, and ,86,mV for 1c+. Each of acridine derivatives gives a linear Brønsted plot for hydride transfer reactions. The experimental slopes were compared with those obtained by Marcus theory. This comparison shows that the kinetic data are consistent with a one-step mechanism involving no high-energy intermediates. Copyright © 2007 John Wiley & Sons, Ltd. [source] Positive reinforcement training affects hematologic and serum chemistry values in captive chimpanzees (Pan troglodytes)AMERICAN JOURNAL OF PRIMATOLOGY, Issue 3 2006Susan P. Lambeth Abstract Positive reinforcement training (PRT) techniques have received considerable attention for their stress reduction potential in the behavioral management of captive nonhuman primates. However, few published empirical studies have provided physiological data to support this position. To address this issue, PRT techniques were used to train chimpanzees (Pan troglodytes) to voluntarily present a leg for an intramuscular (IM) injection of anesthetic. Hematology and serum chemistry profiles were collected from healthy chimpanzees (n=128) of both sexes and various ages during their routine annual physical examinations over a 7-year period. Specific variables potentially indicative of acute stress (i.e., total white blood cell (WBC) counts, absolute segmented neutrophils (SEG), glucose (GLU) levels, and hematocrit (HCT) levels) were analyzed to determine whether the method used to administer the anesthetic (voluntary present for injection vs. involuntary injection) affected the physiological parameters. Subjects that voluntarily presented for an anesthetic injection had significantly lower mean total WBC counts, SEG, and GLU levels than subjects that were involuntarily anesthetized by more traditional means. Within-subjects analyses revealed the same pattern of results. This is one of the first data sets to objectively demonstrate that PRT for voluntary presentation of IM injections of anesthetic can significantly affect some of the physiological measures correlated with stress responses to chemical restraint in captive chimpanzees. Am. J. Primatol. 68:245,256, 2006. © 2006 Wiley-Liss, Inc. [source] X-ray structure of the metcyano form of dehaloperoxidase from Amphitrite ornata: evidence for photoreductive dissociation of the iron,cyanide bondACTA CRYSTALLOGRAPHICA SECTION D, Issue 7 2010V. S. De Serrano X-ray crystal structures of the metcyano form of dehaloperoxidase-hemoglobin (DHP A) from Amphitrite ornata (DHPCN) and the C73S mutant of DHP A (C73SCN) were determined using synchrotron radiation in order to further investigate the geometry of diatomic ligands coordinated to the heme iron. The DHPCN structure was also determined using a rotating-anode source. The structures show evidence of photoreduction of the iron accompanied by dissociation of bound cyanide ion (CN,) that depend on the intensity of the X-ray radiation and the exposure time. The electron density is consistent with diatomic molecules located in two sites in the distal pocket of DHPCN. However, the identities of the diatomic ligands at these two sites are not uniquely determined by the electron-density map. Consequently, density functional theory calculations were conducted in order to determine whether the bond lengths, angles and dissociation energies are consistent with bound CN, or O2 in the iron-bound site. In addition, molecular-dynamics simulations were carried out in order to determine whether the dynamics are consistent with trapped CN, or O2 in the second site of the distal pocket. Based on these calculations and comparison with a previously determined X-ray crystal structure of the C73S,O2 form of DHP [de Serrano et al. (2007), Acta Cryst. D63, 1094,1101], it is concluded that CN, is gradually replaced by O2 as crystalline DHP is photoreduced at 100,K. The ease of photoreduction of DHP A is consistent with the reduction potential, but suggests an alternative activation mechanism for DHP A compared with other peroxidases, which typically have reduction potentials that are 0.5,V more negative. The lability of CN, at 100,K suggests that the distal pocket of DHP A has greater flexibility than most other hemoglobins. [source] Assessing the current Brazilian sugarcane industry and directing developments for maximum fossil fuel mitigation for the international petrochemical marketBIOFUELS, BIOPRODUCTS AND BIOREFINING, Issue 3 2009Ben Brehmer Abstract The EU proposes that 5.75% of the transportation fuels market consist of biofuels by 2010 and the USA proposes that all gasoline be blended with 10% bioethanol by 2012. While these targets have not yet been reached, an aura of critique is emerging, arguing that biofuel mandates are not sustainable. One of the major ensuing topics surrounding biofuel sustainability is the food versus fuel debate in reference to first-generation (or food-based) technology. This article will reveal that for the specific case of sugarcane in Brazil, first-generation bioethanol is more sustainable than expansion to include second-generation (non-food-based) technology. Two life cycle assessments are conducted. First, a cradle-to-factory gate analysis with focus on fossil fuel reduction potential. Fertile land is consumed and occupied by all biomass crops; the biomass option with the highest mitigation potential per land can be considered the most sustainable and least intrusive to food production. Ethanol, on average, can mitigate 104GJ/ha/a, which is equivalent to 17 barrels of oil annually. This can increase to 353GJ/ha/a for the foreseeable best practice situations, higher than the second-generation option. A first-step chemical biorefinery producing ethylene achieves 509GJ/ha/a. Second, the BASF-developed eco-efficiency model, which links both environmental impacts and economic profitability in one, easy-to-interpret graph, is used as validation. Overall it is calculated that a best practice first-generation ethanol and its later dehydration to ethylene are the most eco-efficient options. The biobased economy deserves highly specific assessments. © 2009 Society of Chemical Industry and John Wiley & Sons, Ltd [source] The effect of environmental information on investment allocation decisions , an experimental studyBUSINESS STRATEGY AND THE ENVIRONMENT, Issue 6 2008Pall Rikhardsson Abstract This paper focuses on the use of environmental information in investment decision making. The research approach employed is based on an experiment where three groups of final year finance students were asked to allocate investment funds between two companies based on financial accounts and information material from these companies in which environmental information was included in varying degrees. The overall conclusion is that the qualitative environmental information affects short term allocation decisions, hence indicating a risk reduction potential of environmental information comparable to the classic interpretation of financial information. The quantitative environmental information included in the experiment seems to mitigate rather than extend the directional effect of more environmental information. The evidence also seems to indicate that decision makers are not always aware which information categories affect their decision making. Hence, this has implications for how the potential value of environmental information is to be assessed. Finally, experimental studies as a methodology seem to be better suited to indicate actual effects of different types of information on decision making than attitude surveys. Copyright © 2006 John Wiley & Sons, Ltd and ERP Environment. [source] A Spectroscopic Study of the Reduction of Geometrically Restrained ViologensCHEMISTRY - A EUROPEAN JOURNAL, Issue 28 2007Andrew Abstract A small series of N,N,-dimethyl-4,4,-bipyridinium dication derivatives (commonly known as viologens) has been synthesized and fully characterized; a short dialkoxy tether attached at the 3,3,-positions is used to alter the central dihedral angle. These angles were determined by both single-crystal X-ray diffraction and by computational studies made for the dication, radical cation, and neutral species in a solvent reservoir. The dihedral angle derived for the dication controls the first reduction potential, whereas the geometry of the resultant ,-radical cation determines the magnitude of the second reduction potential. The optical absorption spectra recorded for the various species, and especially those of the radical cations, and the EPR spectral parameters of the ,-radical cations also depend on the molecular geometry. In particular, the central dihedral angle influences the spin density distribution around the aromatic nucleus and, by way of comparison to the parent viologen, it has been possible to resolve the angle dependence from the inherent inductive effect of the strap. These results are considered in terms of the degree of electronic communication between the two aromatic rings, as controlled by the length of the tether. [source] Polyvinyl-Locked versus Free Quaterthiophene: Effect of Spatial Constraints on the Electronic Properties of n -HexylquaterthiopheneCHEMPHYSCHEM, Issue 18 2007Manuela Melucci Dr. Abstract A soluble, low-weight fraction of poly(,-vinyl,,- n -hexyl-quaterthiophene), PT4Hex, having n -hexylquaterthiophenes as side-chain groups, is prepared by free-radical polymerization of ,-vinyl,,-n-hexyl-quaterthiophene and the corresponding properties compared to those of free di- n -hexylquaterthiophene (T4Hex). Optical analysis (absorption and emission) and X-ray diffraction data indicate that in the polyvinyl-locked architecture the quaterthiophene pendants adopt a cofacial arrangement with a mutual distance close enough for ,,, orbitals to overlap (,4 Å). As a consequence of the close chain packing, a shift of the reduction potential of about 0.5 V toward less negative values with respect to free T4Hex, is found for PT4Hex films. Due to its enhanced electron affinity, PT4Hex displays an electron-acceptor behavior when blended with alkylated and silylated quaterthiophenes acting as donors. [source] Synthesis of Substituted Oxazoles from N -Acyl-,-hydroxyamino Acid DerivativesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 27 2008Paula M. T. Ferreira Abstract Several N -acyl-,-hydroxyamino acids were prepared and treated with di- tert -butyl dicarbonate in the presence of 4-(dimethylamino)pyridine, followed by treatment with N,N,N,,N, -tetramethylguanidine to give the corresponding N -acyldehydroamino acids in good to high yields. These were then treated with I2/K2CO3 followed by 1,8-diazabicyclo[5.4.0]undec-7-ene. The methyl esters of N -acyldehydroaminobutyric acid gave the corresponding substituted oxazoles in good to high yields. The N -acyldehydrophenylalanines gave 5-phenyloxazole derivatives in low to moderate yields together with ,-iododehydrophenylalanines. Under the same conditions, N -acyldehydroalanines failed to give the corresponding oxazoles. However, when the reaction was carried out in the absence of DBU, it was possible to isolate the ,,,-diiododehydroalanine derivatives. Although the reason for the different reactivities of the N -acyldehydroamino acids is not completely clear to us, cyclic voltammetry studies showed that the less-reactive derivatives have higher reduction potentials. This suggests that the double bonds in dehydroaminobutyric acid derivatives are more susceptible to electrophilic attack by iodine.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Binding of ligands originates small perturbations on the microscopic thermodynamic properties of a multicentre redox proteinFEBS JOURNAL, Issue 9 2005Carlos A. Salgueiro NMR and visible spectroscopy coupled to redox measurements were used to determine the equilibrium thermodynamic properties of the four haems in cytochrome c3 under conditions in which the protein was bound to ligands, the small anion phosphate and the protein rubredoxin with the iron in the active site replaced by zinc. Comparison of these results with data for the isolated cytochrome shows that binding of ligands causes only small changes in the reduction potentials of the haems and their pairwise interactions, and also that the redox-sensitive acid,base centre responsible for the redox,Bohr effect is essentially unaffected. Although neither of the ligands tested is a physiological partner of cytochrome c3, the small changes observed for the thermodynamic properties of cytochrome c3 bound to these ligands vs. the unbound state, indicate that the thermodynamic properties measured for the isolated protein are relevant for a physiological interpretation of the role of this cytochrome in the bioenergetic metabolism of Desulfovibrio. [source] Copper-containing nitrite reductase from Pseudomonas chlororaphis DSM 50135FEBS JOURNAL, Issue 12 2004Evidence for modulation of the rate of intramolecular electron transfer through nitrite binding to the type 2 copper center The nitrite reductase (Nir) isolated from Pseudomonas chlororaphis DSM 50135 is a blue enzyme, with type 1 and type 2 copper centers, as in all copper-containing Nirs described so far. For the first time, a direct determination of the reduction potentials of both copper centers in a Cu-Nir was performed: type 2 copper (T2Cu), 172 mV and type 1 copper (T1Cu), 298 mV at pH 7.6. Although the obtained values seem to be inconsistent with the established electron-transfer mechanism, EPR data indicate that the binding of nitrite to the T2Cu center increases its potential, favoring the electron-transfer process. Analysis of the EPR spectrum of the turnover form of the enzyme also suggests that the electron-transfer process between T1Cu and T2Cu is the fastest of the three redox processes involved in the catalysis: (a) reduction of T1Cu; (b) oxidation of T1Cu by T2Cu; and (c) reoxidation of T2Cu by NO2,. Electrochemical experiments show that azurin from the same organism can donate electrons to this enzyme. [source] Redox properties of the couple compound I/native enzyme of myeloperoxidase and eosinophil peroxidaseFEBS JOURNAL, Issue 19 2001Jürgen Arnhold The standard reduction potential of the redox couple compound I/native enzyme has been determined for human myeloperoxidase (MPO) and eosinophil peroxidase (EPO) at pH 7.0 and 25 °C. This was achieved by rapid mixing of peroxidases with either hydrogen peroxide or hypochlorous acid and measuring spectrophotometrically concentrations of the reacting species and products at equilibrium. By using hydrogen peroxide, the standard reduction potential at pH 7.0 and 25 °C was 1.16 ± 0.01 V for MPO and 1.10 ± 0.01 V for EPO, independently of the concentration of hydrogen peroxide and peroxidases. In the case of hypochlorous acid, standard reduction potentials were dependent on the hypochlorous acid concentration used. They ranged from 1.16 V at low hypochlorous acid to 1.09 V at higher hypochlorous acid for MPO and from 1.10 V to 1.03 V for EPO. Thus, consistent results for the standard reduction potentials of redox couple compound I/native enzyme of both peroxidases were obtained with all hydrogen peroxide and at low hypochlorous acid concentrations: possible reasons for the deviation at higher concentrations of hypochlorous acid are discussed. They include instability of hypochlorous acid, reactions of hypochlorous acid with different amino-acid side chains in peroxidases as well as the appearance of a compound I,chloride complex. [source] | |||||||||||||||||||||||||||||||||||||