On the suitability of agricultural by-products for the manufacture of granular activated carbon

An investigation of several agricultural by-products revealed that their suitability for activated carbon production is not determined by general material-specific features (elemental composition) but by type-specific features. A coarse-cellular structure (as in wood), which is indicated by porosities of the raw materials higher than 35% is disadvantageous. A specific change in the properties of cokes (porosity, density, hardness) is possible by varying the conditions of pyrolysis. By rapid heating in the pyrolysis step, for instance, macroporous residues are produced. Temperature and burnoff have the greatest influence on the quality of the activated carbon during the activation step. Of the investigated materials, coconut shells yield granular activated carbon of the highest quality. The following order of suitability of raw materials for activated carbon production was established: coconut shells> peach stones> plum stones> hazelnut shells> walnut shells> cherry stones.     

Rudolf Hoesch 90 Jahre

Ohne Zusammenfassung     

Pre‐necking and post‐necking relaxation and creep behavior of polycarbonate: A phenomenological study

Experiments have been performed to investigate the mechanical response of unfilled polycarbonate vis‐à‐vis the influence of prior deformation on stress relaxation and creep. Piecewise linear deformation histories, which involve strain‐controlled tensile loading of a specimen to a maximum load and partial unloading to a target strain/stress point as prologue to a relaxation test, have been shown to qualitatively influence the recorded stress‐time behavior. In particular, the stress magnitude during relaxation first increases and is then followed by a decrease. Analogously, in creep tests during unloading, the strain might decrease and then increase. Time characteristics for this U‐turn in the deformation response are influenced by the placement of the test. The influence of prior specimen conditioning on this phenomenon is investigated by comparing test data from virgin samples to that of specimens having high (～85%) inelastic strain from prior tensile elongation. Findings suggest that the observed persistence in the occurrence of this reversal effect for both types of specimens is evidence of the need to incorporate this behavior into the fold of material modeling. Additionally, this novel relaxation and creep behavior has been observed in other amorphous (poly(phenylene oxide)) and crystalline (high‐density polyethylene) polymers. Polym. Eng. Sci. 44:1783–1791, 2004. © 2004 Society of Plastics Engineers.     

Fluorinated γ-alumina aerogels and xerogels: characterisation and catalytic behaviour

The porosity of -alumina-based materials is an important parameter affecting the extent of fluorination (aerogels > commercial -Al₂O₃ > xerogels) and, consequently, also the textural, acidic and catalytic properties of the final fluorinated materials. Only the highly fiuorinated aluminas having strong Lewis acidic sites catalyse the isomerisation of CHF₂CHF₂ to CF₃CH₂F.     

A survey of approaches to automatic schema matching

Schema matching is a basic problem in many database application domains, such as data integration, E-business, data warehousing, and semantic query processing. In current implementations, schema matching is typically performed manually, which has significant limitations. On the other hand, previous research papers have proposed many techniques to achieve a partial automation of the match operation for specific application domains. We present a taxonomy that covers many of these existing approaches, and we describe the approaches in some detail. In particular, we distinguish between schema-level and instance-level, element-level and structure-level, and language-based and constraint-based matchers. Based on our classification we review some previous match implementations thereby indicating which part of the solution space they cover. We intend our taxonomy and review of past work to be useful when comparing different approaches to schema matching, when developing a new match algorithm, and when implementing a schema matching component. Received: 5 February 2001 / Accepted: 6 September 2001 Published online: 21 November 2001     

Low temperature photoluminescence and infrared dielectric functions of pulsed laser deposited ZnO thin films on silicon

C-axis oriented ZnO thin films were grown on silicon (100) and (111) substrates by pulsed laser deposition. Low temperature photoluminescence spectra show besides the peaks of free excitons, of defect bound excitons, and of a donor-acceptor pair transition a new doublet at 3.328/3.332 eV. The doublet seems to originate from the columnar textured ZnO film structure. A corresponding structural dependence of the broadening parameter of the infrared dielectric functions was derived from spectroscopic ellipsometry in the spectral range from 380 to 1200 cm^− 1. The wave numbers of the E₁ transverse optical and A₁ longitudinal optical phonon modes of the ZnO films on silicon are determined to be 406 and 573 cm^− 1, respectively. These values are slightly smaller than those of single-crystalline ZnO thin films on sapphire.     

Electrode materials for lithium secondary batteries prepared by sol-gel methods

Since the commercialization of lithium secondary batteries in the early of 1990s, their development has been rapid. Nowadays, improving the preparation technology and electrochemical performance of their electrode materials is a major focus in research and development of the materials, power sources and chemistry. Sol-gel methods are a promising way to prepare electrode materials due to their evident advantages over traditional methods, for example, homogeneous mixing at the atomic or molecular level, lower synthesis temperature, shorter heating time, better crystallinity, uniform particle distribution and smaller particle size at nanometer level. In this paper, latest progress in the preparation of electrode materials by sol-gel methods is reviewed, including cathodic ones, e.g., lithium cobalt oxides, lithium nickel oxides, spinel and layered lithium manganese oxides, vanadium oxides and ferrous phosphates, and anodic ones, e.g., tin oxides and titanium oxides. Compared with those prepared by traditional solid-state reaction, the structure stability of the prepared electrode materials and the behavior of lithium intercalation and de-intercalation are much improved. As a result, the prepared products provide better electrochemical performance including reversible capacity, cycling behavior and rate capability. In addition, sol-gel methods can be used to prepare new kinds of electrode materials such as nanowires of LiCoO₂ and nanotubes of V₂O₅, which cannot be easily created by the traditional methods. Further development and application of sol-gel methods will bring about new and better electrode materials, meaning a great promotion to lithium secondary batteries.     

Darreichungsversuche mit vitaminierten Lecksteinen

Zusammenfassung Mehrjährige Versuche mit verschiedenen Lecksteinen, die mit Vitaminen und Spurenelementen versehen waren, erbrachten in Gehegen, Gatterrevieren und in freier Wildbahn keine befriedigende Annahme durch Rotwild, Rehwild und Damwild. Die beste Annahme wurde mit reinen Salzsteinen erreicht, aber auch mit ihnen kein so sicherer Erfolg erzielt, daß eine zuverlässige Darreichung von Mangelstoffen in allen Fällen möglich erscheint.Bei einem Gehegeversuch nahm das Schalenwild bei Verfütterung eines Kraftfutters mit einem Mengen-und Spurenelementzusatz und ausreichender Saftfutterversorgung Lecksteine überhaupt nicht an.Gegenwärtig dürfte deshalb nur dann eine sichere Verabreichung von Mangelstoffen zu erreichen sein, wenn diese beispielsweise in Form eines Pulvers über das Grundfutter gestreut oder in das Grundfutter eingearbeitet werden. Eine wirksame Darreichung über Lecksteine erscheint nicht möglich zu sein. Damit beschränkt sich auch die Verabfolgung von Mangelstoffen im wesentlichen auf die Zeit der Winterfütterung, da bisher nur selten eine ganzjährige Fütterung erfolgt.Die mit Wurmmitteln oder anderen Medikamenten versehenen Lecksteine wurden ebenfalls unbefriedigend angenommen. Zur Sicherung der letzteren Aussage bedarf es noch weiterer Vorlagen.

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Summary Several years' tests with different lick stones provided with vitamines and trace elements did not result in a satisfactory acceptance by red deer, roe deer, and fallow deer in enclosures and fenced reservations. The best acceptance was observed with pure salt stones, but even with these the results obtained were not so certain that a reliable administration of scarcity elements would seem to be possible in all cases.In one enclosure test the hoofed animals did not touch lick stones at all when provided with a strong fodder with an addition of quantity and trace elements and sufficient juicy fodder.At present a guaranteed administration of scarcity elements seems to be attainable only when these are strewn in form of a powder, for instance, upon the basic fodder. An effective administration via lick stones does not seem to be possible. Therefore the administration of scarcity elements is essentially limited to the period of winter feedings as a feeding the whole year round is only scarcely to be found at present.The lick stones provided with vermicides and other remedies where not accepted satisfactorily, neither. In order to prove this latter statement further observations are wanted.

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Résumé Des essais avec différents pierres de lechage enrichis de vitamines et éléments traces et qui s'étendaient sur plusieures années ont démontré que ces pierres ne furent pas acceptés d'une façon satisfaisante per les cerfs, les chevreuils et les daims qu'on tenait en enclos, districts du treillage et districts de chasse libre. De préférence furent acceptés les pierres de sel pur, mais les résultats gagnés ne furent point tellement convaincants, qu'il paraît dans tous les cas possible d'administrer d'une façon positive des substances de carences.Un essai en enclos a démontré que les herbivores ont réfusé les pierres de lechage quand on donnait une alimentation substantielle et enrichie d'éléments de quantités et de traces et une provende suffisamment succulent.Actuellement, on peut seulement arriver à une sure administration de substances de carences si, par exemple, celles-ci sont répandues sous forme de poudre sur le fourrage basique ou entremêlées dans ce fourrage. Une administration efficace par pierres de lechage ne paraît pas possible. Pour cela, l'administration de substances de carences se borne essentiellement sur le temps de fourrage hivernal, puisquéon fourrage rarement pendant toute l'année.Les pierres de lechage pourvus d'un vermifuge ou d'autres médicaments ne furent également pas acceptés d'une façon satisfaisante. Cependant, pour pouvoir assurer cette dernière déclaration, il en faut encore d'autres propositions.