Decomposition of hydrogen peroxide and organic compounds in the presence of dissolved iron and ferrihydrite

This work examines the contribution of solution phase reactions, especially those involving a chain reaction mechanism, to the decomposition of hydrogen peroxide (H2O2) and organic compounds in the presence of dissolved iron and ferrihydrite. In solutions at pH 4, where Fe was introduced as dissolved Fe(III), both H2O2 and 14C-labeled formic acid decomposed at measurable rates that agreed reasonably well with those predicted by a kinetic model of the chain reaction mechanism, using published rate constants extrapolated to pH 4. The ratio of the formic acid and H2O2 decomposition rates, as well as the dramatic effect of tert-butyl alcohol on these rates, confirmed that a solution chain reaction mechanism involving *OH controlled the decomposition kinetics of both compounds. In the presence of ferrihydrite as the iron source, the ratio of the rate of formic acid decomposition to that of H2O2 decomposition was significantly lower than that observed in the presence of only dissolved Fe. Moreover, neither rate diminished drastically upon addition of tert-butyl alcohol, indicating that the solution phase chain reaction is not a dominant decomposition pathway of H2O2 and formic acid. Relative decomposition rates of formic acid and a second *OH probe, benzoic acid, were consistent with oxidation of these compounds by *OH. These observations can be reproduced by a kinetic model including (a) decomposition of H2O2 at the iron oxide surface, producing *OH with lower yield than the reaction sequence with dissolved Fe, and (b) low concentrations of dissolved Fe in the presence of ferrihydrite, preventing propagation of the solution phase chain reaction.     

Redox processes controlling manganese fate and transport in a mountain stream

The biogeochemical processes controlling the speciation and transport of manganese in a Colorado mountain stream were studied using a conservative tracer approach combined with laboratory experiments. The study stream, Lake Fork Creek, receives manganese-rich inflows from a wetland contaminated by acid mine drainage. A conservative tracer experiment was conducted on a 1300-m reach of the stream. Results indicate that manganese was progressively removed from the stream, resulting in a loss of 64 +/- 17 micromol day(-1) m(-1). Laboratory experiments using streamwater, mine effluent, and rocks from the stream showed the importance of surface-catalyzed oxidation and photoreduction on the speciation of manganese. The field and modeling results indicate that light generally promotes oxidation and removal of manganese from the stream, presumably through a photosynthetically enhanced oxidation process. Differences in Mn speciation within the stream suggest that reductive processes affect Mn speciation within the water column. These results identify the rapid oxidation and precipitation of MnOx as a dominant process within this freshwater stream.     

The influence of layered,spherical, and tubular carbon nanomaterials' concentration on the flame retardancy of polypropylene

The characteristic influences of increasing concentrations of graphene, expanded graphite (EG), carbon black (CB), and multiwall carbon nanotubes (MWNT) are investigated on pyrolysis, reaction to small flame, burning behavior, and on electrical, thermal, and rheological properties of flame retarded polypropylene (PP‐FR). The property‐concentration dependency is different for the various material properties, as threshold, linear, and leveling off functions were observed. Increasing concentrations of carbon nanoparticles resulted in a decrease in the electrical resistivity of the polymer by crossing the percolation threshold. The developing nanoparticle network changes melt flow behavior for small shear rates, increases thermal conductivity and therefore, affects the UL 94 classification and oxygen index. The onset temperature of PP decomposition is shifted to temperatures up to 37°C higher; the peak heat release rate is reduced by up to 74% compared to PP‐FR. Both effects leveled off with increasing particle concentration. Among the four carbon nanomaterials tested, graphene presents superior influence on composite properties over the tested concentration range and outperforms commercial CB, MWNT, and EG. POLYM. COMPOS., 36:1230–1241, 2015. © 2014 Society of Plastics Engineers     

Contre-validation de l'organisation hiérarchique de la Mesure de l'Actualisation du Potentiel (MAP).

This study presents a cross-validation of the latent structure of the Measure of Self-actualization of Potential developed recently by G. Leclerc et al (1998) with Canadian people. The sample consisted of 643 French subjects (aged 18-85 yrs). The confirmatory factor analyses supported the hierarchical structure proposed by Leclerc et al. However some modifications were needed to reach an adequate model fit. The sense of these modifications is discussed. Moreover, this scale demonstrated a good internal consistency, and an excellent test-retest reliability. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Experimental Archaeology: Investigation on the Copper–Aluminum–Silicon–Oxygen System

The behavior of the Cu-Al-Si-O system was investigated in the temperature range of 800°–1150°C. X-ray diffraction, infrared spectroscopy, diffusive reflectance, and electron microscopy were applied to obtain information about the influence of sintering, crystallization, and chemical reaction, each of which determines the color of the material. Definition of the artificial term "engobe," opposite to the term "glaze," was possible using copper(II) oxide (CuO) as its indicator. The detected chemical processes render possible explanations about the traditional way of ceramic painting during the 16th century and support the knowledge transfer from the viewpoint of history and that of natural science, as attempted by "archaeometry."     

Chemical and gel electrophoretic characterization of acetylated faba bean protein isolates

The extent of modification of amino and hydroxyl groups in acetylated faba bean protein isolates was determined. Gel electrophoretic studies of unmodified and acetylated faba bean legumin and protein isolates were carried out in acidic and alkaline buffer systems as well as in a SDS-containing system. A remarkable increase of O-acetylation was found after the N-acetylation has reached a degree of about 60%. Structure changes of the proteins were indicated from the gel electrophoresis patterns in the same region of modification. The quantity of acetyl residues fixed on hydroxyl groups in exhaustively modified protein isolates corresponds to 40 % of the total amount of acetyl groups introduced into the proteins. The SDS electrophoresis of the acetylated legumin and protein isolates revealed a remarkable increase of the molecular mass of the acidic α-polypeptide chains only, which is an experimental proof of a preferential acetylation of the latter ones. This gives confirmation of the structural model in which the α-chains are proposed to be situated on the surface of the protein.     

Fault controlled geochemical properties in Lahendong geothermal reservoir Indonesia

Rock and fluid geochemical data from Lahendong, Indonesia, were analyzed to evaluate the influence of fault zones on reservoir properties. It was found that these properties depend on fault-permeability controlled fluid flow.Results from measurements of spring and well water as well as rocks and their hydraulic properties were combined with hydrochemical numerical modeling. The models show that the geothermal field consists of two geochemically distinct reservoir sections. One section is characterized by acidic water, considerable gas discharge and high geothermal-power productivity—all related to increased fault zone permeability. The other section is characterized by neutral water and lower productivity.Increased fluid flow in the highly fractured and permeable areas enhances chemical reaction rates. This results in strong alteration of their surrounding rocks. Numerical models of reactions between water and rock at Lahendong indicate the main alteration products are clay minerals. A geochemical conceptual model illustrates the relation between geochemistry and permeability and their distribution within the area.Our conceptual model illustrates the relation between geochemistry and fault-zone permeability within the Lahendong area. Further mapping of fault-related permeability would support sustainable energy exploitation by avoiding low-productive wells or the production of highly corroding waters, both there and elsewhere in the world.     

The influence of values in shared (medical) decision making

The Shared Decision Making model is becoming increasingly popular also in the German-speaking context, but it only considers values of patients to be relevant for medical decisions. Nevertheless, studies show that the values of physicians are also influential in medical decisions. Moreover, physicians are often unaware of this influence, which makes it impossible to control it. The influence of both patients’ and physicians’ values is examined from an empirical and normative perspective. The review about the empirical data provides a necessary overview about the status quo, whereas I deduct rules for value-influenced behaviour in the decision making process in the normative approach. Therefore, different scenarios are taken into account to explore in which situations it is acceptable for physicians to let their values be part of the decision making process. The conscious use of values is only possible, when physicians are aware of their influence. To raise awareness, the best option would be to educate future physicians about it in their training. Therefore, this article provides a teaching concept for a unit that could be part of an ethics class for physicians in training. Furthermore, patient’s rights and responsibilities in the decision making process are discussed. I conclude that it is necessary to take the influence of values (more) into account and include this knowledge into the training of physicians. Conclusively, recommendations for patients and physicians and their dealing with values in shared decision making processes are suggested.     

Finishing of polycrystalline diamond tools by combining laser ablation with grinding

In manufacturing polycrystalline diamond (PCD) tools, the finishing process in order to obtain the required surface and edge quality and to remove the damaged PCD layer induced by the prior manufacturing steps is mostly done by grinding. However, grinding is currently inefficient and costly due to low material removal rates and high wear of the grinding wheel. The project “Pro-PKD” aims to increase throughput and reduce tool wear by an additional laser ablation step prior to grinding. In first process investigations, the influence of different laser parameters on the ablation rate was analyzed and an optimum parameter set for maximum ablation efficiency was found. By measuring the overall material removal from the grinding wheel and the PCD tool, it could be shown that the G-ratio can be increased by at least a factor of two. Furthermore, the time required for grinding can be significantly shortened. As the time needed for laser ablation is only several seconds, in this way the whole time required for the finishing process can be reduced. In any case, the combined process presented here has the distinct advantage that it can be implemented into already existing grinding machines with comparatively low investment costs.     

What affects public acceptance of recycled and desalinated water?

This paper identifies factors that are associated with higher levels of public acceptance for recycled and desalinated water. For the first time, a wide range of hypothesized factors, both of socio-demographic and psychographic nature, are included simultaneously. The key results, based on a survey study of about 3000 respondents are that: (1) drivers of the stated likelihood of using desalinated water differ somewhat from drivers of the stated likelihood of using recycled water; (2) positive perceptions of, and knowledge about, the respective water source are key drivers for the stated likelihood of usage; and (3) awareness of water scarcity, as well as prior experience with using water from alternative sources, increases the stated likelihood of use. Practical recommendations for public policy makers, such as key messages to be communicated to the public, are derived.