bluuebunny/crossref_metadata_2025_split huggingface dataset:
Neue Prozessoptionen für die Nutzung von Zeolithen in überkritischen Fluiden und ionischen Flüssigkeiten
Authors: Gläser R. 
Published: July 2006

AbstractÜberkritische Fluide und ionische Flüssigkeiten bieten interessante Optionen für die Modifikation und Nutzung von Zeolithen als Adsorbenzien und Katalysatoren. Nach einer kurzen Beschreibung der wichtigsten Eigenschaften dieser Lösungsmittel werden Beispiele für Anwendungen von Zeolithen in überkritischen Fluiden und ionischen Flüssigkeiten aus der aktuellen Literatur besprochen. Dabei wird im Besonderen auf den Einfluss der Reaktionsmedien auf die Vorgänge im Inneren von Zeolithporen eingegangen, z. B. bei formselektiven Umsetzungen an Zeolithkatalysatoren. Aus den behandelten Beispielen werden das Potenzial und die zukünftigen Herausforderungen für die Nutzung von Zeolithen in überkritischen Fluiden und ionischen Flüssigkeiten abgeleitet. Besonders attraktive Prozessoptionen ergeben sich aus einer kombinierten Anwendung von sowohl ionischen Flüssigkeiten als auch überkritischen Fluiden.
Der isotherme Labor‐Festbettreaktor mit quantitativer schneller Online‐Analytik als vielseitiges Instrument in der Redoxkatalyse
Authors: Aßmann J. , Muhler M. 
Published: July 2006

AbstractDer isotherme Festbettreaktor mit quantitativer schneller Online‐Analytik ermöglicht einerseits eine schnelle wissensbasierte Optimierung der Katalysatorsynthese bei Gasphasenprozessen. Andererseits lassen sich durch die enge Kopplung von stationären und transienten kinetischen Experimenten in diesem Reaktor vertiefte Einblicke in die Mechanismen der Redoxkatalyse gewinnen. Durch die Verknüpfung mit Befunden aus schwingungsspektroskopischen In‐situ‐Experimenten kann daraus eine rationale Katalysatoroptimierung resultieren. Der Übersichtsbeitrag erläutert die Umsetzung dieses Konzepts am Lehrstuhl für Technische Chemie der Ruhr‐Universität Bochum anhand der chemischen Gasphasensynthese von Kohlenstoff‐Fasern, der oxidativen Aminierung von Benzol zu Anilin und der CO‐Oxidation mit RuO2.
Perspektiven industrieller Katalyse – Die Zukunft gestalten
Authors: Wernicke H.‐J. , Fischer R. W. 
Published: July 2006

AbstractFast kein chemischer Prozess – sofern thermodynamisch erlaubt – kommt ohne katalytische Schritte aus. Praktisch alle chemischen Reaktionen lassen sich per Katalyse effizienter gestalten und leichter durchführen. Anhand ausgesuchter Beispiele aus dem Bereich der industriell angewandten Katalyse werden die Bedeutung und die sich daraus ableitenden Perspektiven dieser Schlüsseltechnologie betrachtet, gewissermaßen ein „Katalyseblitzlicht”︁ zum Anfang des 21. Jahrhunderts.
Can the Clusters Zr6O4(OH)4(OOCR)12 and [Zr6O4(OH)4(OOCR)12]2 Be Converted into Each Other?
Authors: Puchberger Michael , Kogler Franz René , Jupa Myhedin , Gross Silvia , Fric Helmut , Kickelbick Guido , Schubert Ulrich 
Published: July 2006

AbstractUpon reaction of zirconium alkoxides, Zr(OR)4, with carboxylic acids, the clusters Zr6O4(OH)4(OOCR)12 (Zr6) or [Zr6O4(OH)4(OOCR)12]2 (Zr12) were obtained, depending on the employed carboxylic acid. The structures of Zr12 clusters with acetate, propionate, vinyl acetate or 3,3′‐dimethylacrylate ligands were determined by single‐crystal X‐ray diffraction, as well as that of methacrylate/acetate and methacrylate/propionate mixed‐ligand clusters. The structure of the hafnium cluster [Hf6O4(OH)4(acetate)12]2 is also reported for comparison. The Zr12 clusters are structurally related to the Zr6 clusters since they are composed of two Zr6 sub‐units which are bridged by four carboxylate ligands. In each compound, carboxylic acid molecules interact with the cluster by hydrogen bonding to part of the μ3‐OH ligands. The clusters are highly dynamic in solution, due to site exchange of the carboxylate ligands; low‐temperature NMR spectra of the clusters correspond to the solid‐state structures. The Zr6 and Zr12 clusters can be clearly distinguished by their solution NMR spectra. Reactions between selected Zr12 clusters and carboxylic acids led to the conclusion, that only part of the ligands is accessible for ligand exchange reactions. In contrast, all ligands were exchanged when the Zr6 cluster Zr6O4(OH)4(methacrylate)12 was treated with an excess of propionic acid, and Zr6O4(OH)4(propionate)12 was formed. However, the Zr12 cluster [Zr6O4(OH)4(propionate)12]2 was obtained from the reaction of Zr(OBu)4 with propionic acid. The Zr6 and Zr12 clusters thus do not interconvert at the given reaction conditions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Direct Asymmetric Aldol‐Tishchenko Reaction
Authors: Mlynarski Jacek 
Published: July 2006

AbstractThe asymmetric direct aldol reaction of nonpreactivated substrates constitutes one of the most powerful tools in current synthetic chemistry. In the last few years, chiral metal complexes have been found to catalyze the direct aldol addition of unmodified ketones to aldehydes with both high efficiency and selectivity. However, many problems have to be overcome in this still young field of chemistry. The most challenging aspect of this chemistry is the substrate limitation of known catalysts. In this field, the asymmetric aldol‐Tishchenko reaction can be regarded as a parallel methodology that expands the scope of possible applications. In the aldol‐Tishchenko reaction, two aldehyde molecules undergo addition to form an aldol adduct, which is subsequently reduced by a third aldehyde to yield 1,3‐diol monoesters through a [3,3]‐bond reorganization. With the use of aldehydes and ketones in the aldol‐Tishchenko reaction, diols with three adjacent stereogenic centers can be created in one single operation. Thus, the reaction can be regarded as an extremely atom efficient method for the construction of enantiomerically enriched products that can serve as fundamental building blocks in synthesis. Moreover, the aldol‐Tishchenko condensation is nowadays the most efficient methodology available for the direct catalytic asymmetric aldol reaction of methylene ketones. This article provides a synopsis of this field and highlights some of the challenges that still remain.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Fiberboards Based on Sugarcane Bagasse Lignin and Fibers
Authors: Hoareau William , Oliveira Francielli B. , Grelier Stephane , Siegmund Bernard , Frollini Elisabete , Castellan Alain 
Published: July 2006

AbstractSummary: Fiberboards were prepared using phenolic type resins (phenol‐formaldehyde) and sugarcane bagasse fibers. Lignin extracted through an organosolv process from sugarcane bagasse was used as substitute of phenol in phenolic resins from 40 (lignin‐phenol‐formaldehyde) to 100 wt.‐% (lignin‐formaldehyde) substitution. Some of the fibers were chemically modified by oxidation with chlorine dioxide and treatment with furfuryl alcohol (FA), leading to fibers coated with polyfurfuryl alcohol. Thermal analysis (DSC and TGA) of the prepolymers allowed setting up an efficient curing to prepare fiberboards. Impact strength and water absorption were measured showing the importance of the curing pressure to obtain good performance. When chemically modified fibers were used to prepare board samples, enhanced durability against white root fungi is observed, and to a less degree against brown root fungi. Sugarcane bagasse fiberboards were prepared from prepolymers where lignin substituted phenol up to 100%. This replaces these materials in advantageous position, relating to those prepared from phenol‐formaldehyde resins, due to their high content of renewable raw materials. The results obtained are promising for the utilization of sugarcane bagasse as raw materials for preparing fiberboards to be used in tropical areas.Stabilization of sugarcane bagasse fiberboards made with unmodified and modified (ClO2 + furfuryl alcohol) fibers and phenolic resin after 8 weeks exposure against fungi.magnified imageStabilization of sugarcane bagasse fiberboards made with unmodified and modified (ClO2 + furfuryl alcohol) fibers and phenolic resin after 8 weeks exposure against fungi.
Compatibilization of Conductive Polyethylene/Polyaniline Blends
Authors: Annala Minna , Löfgren Barbro 
Published: July 2006

AbstractSummary: The compatibilization of polyethylene/polyaniline (PE/PANI) blends and the preparation of plasticized PANI/camphorsulfonic acid (CSA) complexes suitable for melt blending were studied. Rheological properties of the components essentially affected the morphology of the blend and thereby the electrical conductivity. The hydrogen bonds between the PANI complex and the functionalized metallocene PE used as compatibilizer compensated the unfavorable viscosities of the components. Mechanical properties of PE/PANI blends were improved, and electrical conductivity of the blends remained the same or increased through addition of functionalized metallocene polyethylene. Plasticized PANI/CSA complex with good electrical conductivity was successfully prepared.Compatibilization of PANI/CSA complex and OH‐functionalized polyethylene.magnified imageCompatibilization of PANI/CSA complex and OH‐functionalized polyethylene.
Synthesis, Characterization and Properties of Novel Poly(urethane‐imide) Networks as Electrical Insulators with Improved Thermal Stability
Authors: Yeganeh Hamid , Atai Mohammad , Hojati Talemi Pejman , Jamshidi Sadegh 
Published: July 2006

AbstractSummary: A new series of thermoplastic poly(urethane‐imide)s (TPUI1‐4) containing hydroxyl groups in the backbone was synthesized from the reaction of epoxy‐terminated polyurethane prepolymers (EPU1‐4) and an imide containing diacid (DIDA) chain extender under optimized reaction conditions. EPU1‐4 was prepared through end‐functionalization of NCO‐terminated polyurethanes based on polyester polyol (CAPA) and hexamethylene diisocyanate with glycidol. A blocked isocyanate (BIC) was made from the reaction of trimethylol propane (TMP), toluene diisocyanate (TDI) and N‐methylaniline (NMA). Polymer networks were prepared from the reaction of librated isocyanate groups of BIC with hydroxyl groups of TPUIs. The starting materials and polymers were characterized by conventional spectroscopic methods and the physical, thermal and electrical properties of crosslinked networks were studied. Investigation of the recorded properties for these samples showed considerable improvement in thermal and electrical properties in comparison to common polyurethanes.Synthetic route for preparation of TPUIs.magnified imageSynthetic route for preparation of TPUIs.
Conducting Composites of Polyurethane Resin and Polypyrrole: Solvent‐Free Preparation, Electrical, and Mechanical Properties
Authors: Deligöz Hüseyin , Tieke Bernd 
Published: July 2006

AbstractSummary: Three methods were used for solvent‐free preparation of conducting composites of PUR and PPy. In all cases, PUR was prepared from TDI and hydroxol 15‐W as polyol cross‐linker, whereas PPy was obtained upon oxidative coupling of Py using ferric chloride as oxidant. In method 1, PPy powder was dispersed in hydroxol. After addition of TDI the mixture was cured to yield the final product. In method 2, ferric chloride and Py were dissolved in hydroxol and a PPy dispersion was obtained. Then TDI was added and the final product was obtained upon curing. In method 3, Py was dissolved in TDI and ferric chloride dissolved in hydroxol. Then the two solutions were mixed and cured resulting in the simultaneous formation of PPy and PUR. Method 1 led to composites with a specific electrical conductivity σ of 10−10 S · cm−1 and a Shore A hardness of 40 to 55. Using methods 2 and 3, composites with σ values of 10−7 S · cm−1 and a hardness of 30 to 40 were obtained. Presence of moisture increased the σ values and decreased the hardness. Due to the solvent‐free preparation, the maximum PPy content of the samples was limited to 10 wt.‐%. The studies also demonstrated that the conductivity was mainly dependent on the amount of ferric chloride present in the sample and not on the PPy content, suggesting that the conductivity was ionic.Flow diagram of different preparation methods for PUR–PPy composites.magnified imageFlow diagram of different preparation methods for PUR–PPy composites.
Quantification of Reductive Species Produced by High Voltage Electrical Discharges in Water
Authors: Sahni Mayank , Locke Bruce R. 
Published: July 2006

AbstractSummary: The formation of reductive species has already been documented in various advanced oxidation–reduction processes (AORP) such as ultrasound and radiation processes. Reductive species are important in degrading mixed aqueous wastes and nitro‐ and chloro‐contaminants to achieve higher degradation efficiencies than can be attained by the reaction of contaminants with hydroxyl radicals (the primary reactive species produced by all AORP). The present study quantifies the total amount of reductive species produced by aqueous phase high voltage pulsed electrical discharge, using chemical probes tetranitromethane and nitroblue tetrazolium chloride. The effects of various electrical, physical, and chemical parameters on the generation of reductive species are investigated.
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Characterization of isoquinoline alkaloids, diterpenoids and steroids in the Chinese herb Jin‐Guo‐Lan (Tinospora sagittata and Tinospora capillipes) by high‐performance liquid chromatography/electrospray ionization with multistage mass spectrometry
Authors: Zhang Yufeng , Shi Qirong , Shi Peiying , Zhang Weidong , Cheng Yiyu 
Published: July 2006

AbstractThis study sought to determine the primary components (isoquinoline alkaloids, diterpenoids and steroids) in crude extracts of the Chinese herb Jin‐Guo‐Lan, prepared from the roots of Tinospora sagittata and T. capillipes, by liquid chromatography/electrospray ionization multistage mass spectrometry coupled with diode‐array detection (LC‐DAD/ESI‐MSn). After separation on a reversed‐phase C18 column using gradient elution, positive and negative ESI‐MS experiments were performed. In positive ion mode, the three types of compounds showed very different characteristic ions: strong [M]+ or [M+H]+ ions were observed for isoquinoline alkaloids; [M+NH4]+ and/or [M+HCO2]+ for diterpenoids; [M+HnH2O]+ (n=1–3) for steroids. These adduct ions and/or fragments were used to deduce the mass and categories of known and unknown components in crude extracts, and their structures were further confirmed by ESI‐MSn in positive ion mode. Moreover, UV absorption peaks obtained from DAD provided useful functional group information to aid the MSn‐based identification. As a result, 11 compounds were unambiguously identified by comparing with standard compounds and 13 compounds were tentatively identified or deduced according to their MSn data. Two of these compounds (13‐hydroxycolumbamine and 13‐hydroxyjatrorrhizine) were found to be new compounds and another one (13‐hydroxypalmatine) was detected for the first time as a natural product. In addition, a [M·CH3H2O].+ ion in MS2 of [M]+ after in‐source collision‐induced dissociation was used to differentiate positional isomers of protoberberine alkaloids, columbamine and jatrorrhizine. Although the roots of T. sagittata and T. capillipes contain almost identical compounds, the content of the compounds in them is dramatically different, suggesting the necessity for further comparison of the bioactivities of the two species. Copyright © 2006 John Wiley & Sons, Ltd.
Interactions between striped bass (Morone saxatilis) rebuilding programmes and the conservation of Atlantic salmon (Salmo salar) and other anadromous fish species in the USA
Authors: Grout Douglas E. 
Published: July 2006

Abstract
Anadromous populations of striped bass occur along the Atlantic coast of the US from Maine to North Carolina. Recruitment overfishing and declining water quality led to substantial reductions in striped bass abundance during the 1970s and 1980s. Cooperative interstate fishery management of striped bass began in 1981, with the development of a fishery management plan by the Atlantic States Marine Fisheries Commission, an organization of Atlantic coastal states. Effective fishery management and additional research and monitoring contributed to a tenfold increase in abundance of striped bass stocks by the late 1990s. This dramatic increase resulted in increased predation on a variety of anadromous fish species including American shad, blueback herring, and alewives. Predation by striped bass on Atlantic salmon smolts in North America has been documented, but the impact of this predation has not been quantified. Moderate to strong correlations were found between estimates of striped bass abundance and the return of Atlantic salmon to three of the four major New England salmon rivers. Further research is required to quantify the proportion of smolt production consumed by striped bass, particularly for salmon populations listed as endangered under the US Endangered Species Act.
Size of wild and hatchery-reared Atlantic salmon populations in the northern Baltic Sea estimated by a stratified mark-recapture method
Authors: Siira Antti , Suuronen Petri , Kreivi Petri , Erkinaro Jaakko 
Published: July 2006

Abstract
We estimated the total size of the Atlantic salmon (Salmo salar) population complex (wild and cultured) in the Gulf of Bothnia, northern Baltic Sea, using a stratified mark-recapture method. In 2001 and 2002, 1970 salmon were captured by the commercial trapnet fishery and tagged with external arrow tags. A total of 349 tagged fish was later recaptured among 65 180 salmon screened for tags. Recoveries were gathered by the commercial trapnets and by screening fish entering counting facilities in rivers and broodstock fisheries at the river mouths. In addition, tags were recovered from recreational river catches. Our estimates suggest that the total size of the migrating population in both years was about 230 000 fish. Proportions of wild and cultured salmon differed between the two years. In 2001, the proportion of wild salmon was 37%; the corresponding figure for 2002 was 62%. Based on estimates of wild salmon smolt production and the number of released smolts, the estimated proportion of cultured smolts that survived the feeding migration and returned to the Gulf of Bothnia (2–4%) was approximately 2.5–4.5 times lower than that of wild smolts (9–10%).
Otolith shape and temporal stability of spawning groups of Icelandic cod (Gadus morhua L.)
Authors: Jónsdóttir Ingibjörg G. , Campana Steven E. , Marteinsdottir Gudrun 
Published: July 2006

AbstractDuring the past 5–10 years, studies exploring small-scale structure of cod populations have provided accumulating evidence for the existence of local populations. In Iceland, all cod have been thought to belong to a single management unit. Recent studies on genetic and life history variation have, however, indicated the existence of local populations. The main objective of this study is to explore the potential existence of local populations by use of otolith shape to discriminate between spawning groups of Icelandic cod. Otoliths were sampled from mature and spawning cod at spawning locations around Iceland in 2002 and 2003, and otolith shape was described using variables correlated with size (otolith area, length, width, perimeter, and weight) as well as shape (rectangularity, circularity, and 10 Fourier coefficients). Only standardized otolith variables were used so as to remove the effect of otolith size on the shape variables. Cod were on average larger and older south of Iceland, where ambient temperature was higher than northwest, north, and east of Iceland. Otolith shape effectively discriminated between cod north and south of Iceland, and it was also possible to discriminate among cod spawning below and above 125 m at spawning locations south of Iceland. Recent genetic and tagging studies have indicated differences between cod at these two depths. Correct classification of groups of cod at the different spawning locations ranged between 0% and 44%. Incorrectly classified cod were in most cases classified to adjacent spawning locations, and a high percentage of cod south of Iceland was classified to other southern locations and cod north of Iceland to other northern locations. The temporal stability of otolith shape was studied at seven spawning locations in two consecutive years. Otolith shape differences were greater between locations than among years within a location. The spawning groups are therefore likely to have remained separate during much of their lifetime.
Focal supplier opportunism in supermarket retailer category management
Authors: Morgan Neil A. , Kaleka Anna , Gooner Richard A. 
Published: July 2006

AbstractCommon prescriptions for improving the performance of supermarket retailers center on using key suppliers as “category captains” and leveraging their resources and capabilities to implement effective category management that will both reduce retailer costs and provide a basis for differentiation. However, despite these widespread prescriptions, the potential for supplier opportunism means that supermarket retailers are either skeptical or have failed to make such category management relationships with key suppliers work. Drawing on agency, transaction costs, and network theory, we synthesize insights from qualitative fieldwork with retailer and supplier managers and primary data from 73 category managers in U.K. supermarket retailers to empirically examine antecedents and consequences of category‐level focal supplier opportunism. Our findings suggest that focal supplier opportunism decreases retailer category performance and increases militant behaviors among non‐focal suppliers in the category supply chain. Consistent with retailer fears, we find that focal suppliers with significant influence in retailers’ category management efforts are more likely to engage in opportunistic behavior. However, our results also reveal that retailer fears that being dependent on a focal supplier will lead to greater supplier opportunism are largely unfounded, while supplier dependence on the retailer is also unrelated to focal supplier opportunism. Finally, we find that retailers’ ability to monitor – but not to punish – its focal suppliers is negatively related to opportunistic behavior among focal suppliers.
Forecasting the macroeconomy with contemporaneous financial market information: Europe and the United States
Authors: Junttila Juha 
Published: July 2006

AbstractUsing Economic Tracking Portfolios (ETP), I find that it is possible to forecast future values of inflation and changes in industrial production in the United States and three core euro countries – Italy, France and Germany – utilizing only current and past financial market information. The longer the forecasting horizon, the better the forecasts based solely on financial market information compared to results from other methods. Of the countries I analyze, the overall forecasting performance of the tracking portfolios is the best for the U.S., and my method outperforms the forecasting performance of a VAR approach.