ARCHAEOMETRY, Issue 3 2006
A. SILVESTRI
This paper reports the results of an experimental study performed on Campanian littoral sand, together with a careful philological analysis of Pliny's text concerning the production of glass using the above sand in order to verify its suitability. Accurate chemical and mineralogical characterization of sand samples and experimental glasses was carried out, proving the unsuitability of sand for glass production in its original state. Taking into account both the results of the philological analysis of Pliny's text and the mineralogical assemblage of the sand, a new hypothesis regarding Roman glass-making technology is proposed and tested here. The technology implies the production of ,quartz-enriched' sand by means of selective grindings according to the different degrees of hardness and cleavage of the mineralogical phases. Melting experiments, carried out on treated sand and in the temperature range compatible with Roman technology, yielded a glass with composition similar to those of typical Roman glasses. Therefore, new perspectives on the sources of supply of raw materials, hitherto debated, are opened up. [source]

CORRESPONDENCE AND DISCRIMINANT ANALYSES OF SAND AND SAND TEMPER COMPOSITIONS, TONTO BASIN, ARIZONA,

ARCHAEOMETRY, Issue 2 2000
J. M. HEIDKE
Geologists use petrographic modal analysis to relate fluvial sand composition to source rock composition, thus establishing provenance. Archaeologists seeking to establish provenance of sand temper in pottery can use similar petrographic methods, but their finer scale of investigation requires more precise statistical tools than those employed by geologists. A quantitative method for performing that task is presented. It utilizes correspondence analysis and discriminant analysis of logratio transformed point-count data to define petrofacies, or sand temper resource procurement zones. The procedure is illustrated with sand and sand-tempered sherd samples collected from the Tonto Basin, central Arizona; temporal trends in utilitarian ceramic production c. AD 100,1350 are reviewed. [source]

FILLING HISTORY OF THE MAUI B FIELD, NEW ZEALAND: NEW INFORMATION FROM OIL INCLUSIONS IN AUTHIGENIC MINERALS FROM THE OIL LEG IN THE MAUI-B1 WELL F SANDS

JOURNAL OF PETROLEUM GEOLOGY, Issue 3 2009
S. D. Killops
A study of the molecular composition of oil inclusions in the Maui field, Taranaki Basin, New Zealand, reveals compositional variation in oil during the filling history of the Paleocene reservoir. The homogenization temperatures of aqueous inclusions in quartz suggest that oil in genetically associated inclusions first reached the proto-Maui structure about 7.0,7.5 Ma ago, and that an effective trap was present at the Paleocene F-sands level, given the abundant oil inclusions. This date coincides with what is believed to represent the early stages of structural development of the trap. The Maui or Pihama sub-basin appears the most likely kitchen for this early charge. The quartz-included oil exhibits a biomarker distribution with a slightly more marine-influenced signature than an oil stain from the same core plug, oil included in authigenic feldspar, and oil-production samples from the overlying Eocene D sands as well as the F sands. The greater similarity of the feldspar-included oil to the production oils together with its possibly slightly lower maturity suggest that the feldspar inclusions formed later than the quartz inclusions. Otherwise, all oil samples examined (inclusion oil, oil / bitumen in sandstones and producible oil) are of similar maturity. [source]

Sand in the machinery?

EUROPEAN JOURNAL OF POLITICAL RESEARCH, Issue 6 2005
Comparing bureaucrats', politicians' attitudes toward public sector reform
This article addresses the general notion that bureaucrats may oppose the introduction of reforms in the public sector, and that their views concerning reform will differ from that of politicians. Such a situation may create a sense of conflict between the two spheres, but different views on public sector reform can also follow other conflict dimensions. Two such dimensions are outlined: the one between political parties, and the one between a political-administrative elite and a group of more peripheral politicians and administrators. The hypotheses set forward are tested by comparing local authority politicians' and administrative leaders' views on public sector reform. The data does not support the notion of general conflict between politicians and administrators, or that of conflict of interest between an elite and a more peripheral group. In general, politicians and administrators have rather similar views, but there is a wide difference between political parties. The administration places itself somewhat in the middle between political extremes, being moderately positive towards most reforms. [source]

Aggregate sources and supplies in Jamaica

GEOLOGICAL JOURNAL, Issue 5 2008
Peter W. Scott
Abstract Aggregate resources in Jamaica are sand and gravel found in active river systems, and limestone. Other rocks in Cretaceous inliers and elsewhere are generally too weathered at the surface or too remote from centres of population to be considered suitable as significant sources of aggregates. Sand and gravel generally supplies the south of the country with limestone production and markets being concentrated along the northern coastal areas. Limestone aggregates are produced by ripping and crushing, blasting being uncommon. Sand and gravel are often simply processed using a single screen, although fixed crushing and screening plant are used in some operations. The aggregate industry operates inefficiently, generally utilizing old plant, although an economic assessment shows it to be very profitable. Substitution of sand and gravel by limestone would help mitigate the negative environmental impact of extraction of aggregates from active river systems, but would considerably distort the supply of aggregates throughout the country. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Insights into biaxial extensional tectonics: an examplefrom the Sand,kl, Graben, West Anatolia, Turkey

GEOLOGICAL JOURNAL, Issue 1 2003
Mustafa Cihan
Abstract West Anatolia, together with the Aegean Sea and the easternmost part of Europe, is one of the best examples of continental extensional tectonics. It is a complex area bounded by the Aegean,Cyprus Arc to the south and the North Anatolian Fault Zone (NAFZ) to the north. Within this complex and enigmatic framework, the Sand,kl, Graben (10,km wide, 30,km long) has formed at the eastern continuation of the Western Anatolian extensional province at the north-northwestward edge of the Isparta Angle. Recent studies have suggested that the horst,graben structures in West Anatolia formed in two distinct extensional phases. According to this model the first phase of extension commenced in the Early,Middle Miocene and the last, which is accepted as the onset of neotectonic regime, in Early Pliocene. However, it is controversial whether two-phase extension was separated by a short period of erosion or compression during Late Miocene,Early Pliocene. Both field observations and kinematic analysis imply that the Sand,kl, Graben has existed since the Late Pliocene, with biaxial extension on its margins which does not necessarily indicate rotation of regional stress distribution in time. Although the graben formed later in the neotectonic period, the commencement of extension in the area could be Early Pliocene (c. 5,Ma) following a severe but short time of erosion at the end of Late Miocene. The onset of the extensional regime might be due to the initiation of westward motion of Anatolian Platelet along the NAFZ that could be triggered by the higher rate of subduction at the east Aegean,Cyprus Arc in the south of the Aegean Sea. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Effects of Mixing Granular Iron with Sand on the Kinetics of Trichloroethylene Reduction

GROUND WATER MONITORING & REMEDIATION, Issue 2 2009
Erping Bi
A substantial cost of granular iron permeable reactive barriers is that of the granular iron itself. Cutting the iron with sand can reduce costs, but several performance issues arise. In particular, reaction rates are expected to decline as the percentage of iron in the blend is diminished. This might occur simply as a function of iron content, or mass transfer effects may play a role in a much less predictable fashion. Column experiments were conducted to investigate the performance consequences of mixing Connelly granular iron with sand using the reduction kinetics of trichloroethylene (TCE) to quantify the changes. Five mixing ratios (i.e., 100%, 85%, 75%, 50%, and 25% of iron by weight) were studied. The experimental data showed that there is a noticeable decrease in the reaction rate when the content of sand is 25% by weight (iron mass to pore volume ratio, Fe/Vp = 3548 g/L) or greater. An analysis of the reaction kinetics, using the Langmuir-Hinshelwood rate equation, indicated that mass transfer became an apparent cause of rate loss when the iron content fell below 50% by weight (Fe/Vp = 2223 g/L). Paradoxically, there were tentative indications that TCE removal rates were higher in a 15% sand + 85% iron mixture (Fe/Vp = 4416 g/L) than they were in 100% iron (Fe/Vp = 4577 g/L). This subtle improvement in performance might be due to an increase of iron surface available for contact with TCE, due to grain packing in the sand-iron mixture. [source]

Effects of sand and process water pH on toluene diluted heavy oil in water emulsions in turbulent flow

AICHE JOURNAL, Issue 1 2009
Chandra W. Angle
Abstract The presence of sand in heavy oil production is known to enhance oil recovery. Sand can also be detrimental depending on the properties of the sand,water interface. In this process, the water soluble material interacts with both sand and oil droplets and affects emulsion stability. The formation and stability of heavy oil-in-water emulsions during turbulent flow using batch process stirred-tank mixing of oil, sand, and water were investigated at three pH. Size distributions were measured by laser diffraction. High-speed video photomicrography was used to observe the process during mixing. Results showed that the presence of sand enhanced formation of stable, fine emulsion at basic pH 8.5. When the pH of the water was reduced below 6.5 both sand and droplets surface properties changed, the emulsions became less stable and coalescence was apparent. The sand grains acted as coalescers at low pH and enhanced breakage at high pH. © Her Majesty the Queen in Right of Canada, as represented by the Minister of Natural Resources, 2008 AIChE J, 2009 [source]

Transforming powder mechanical properties by core/shell structure: Compressible sand

JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 11 2010
Limin Shi
Abstract Some active pharmaceutical ingredients possess poor mechanical properties and are not suitable for tableting. Using fine sand (silicon dioxide), we show that a core/shell structure, where a core particle (sand) is coated with a thin layer of polyvinylpyrrolidone (PVP), can profoundly improve powder compaction properties. Sand coated with 5% PVP could be compressed into intact tablets. Under a given compaction pressure, tablet tensile strength increases dramatically with the amount of coating. This is in sharp contrast to poor compaction properties of physical mixtures, where intact tablets cannot be made when PVP content is 20% or less. The profoundly improved tabletability of core/shell particles is attributed to the formation of a continuous three-dimensional bonding network in the tablet. © 2010 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99:4458,4462, 2010 [source]

Compound-specific stable-isotope (,13C) analysis in soil science

JOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 5 2005
Bruno Glaser
Abstract This review provides current state of the art of compound-specific stable-isotope-ratio mass spectrometry (,13C) and gives an overview on innovative applications in soil science. After a short introduction on the background of stable C isotopes and their ecological significance, different techniques for compound-specific stable-isotope analysis are compared. Analogous to the ,13C analysis in bulk samples, by means of elemental analyzer,isotope-ratio mass spectrometry, physical fractions such as particle-size fractions, soil microbial biomass, and water-soluble organic C can be analyzed. The main focus of this review is, however, to discuss the isotope composition of chemical fractions (so-called molecular markers) indicating plant- (pentoses, long-chain n-alkanes, lignin phenols) and microbial-derived residues (phospholipid fatty acids, hexoses, amino sugars, and short-chain n-alkanes) as well as other interesting soil constituents such as "black carbon" and polycyclic aromatic hydrocarbons. For this purpose, innovative techniques such as pyrolysis,gas chromatography,combustion,isotope-ratio mass spectrometry, gas chromatography,combustion,isotope-ratio mass spectrometry, or liquid chromatography,combustion,isotope-ratio mass spectrometry were compared. These techniques can be used in general for two purposes, (1) to quantify sequestration and turnover of specific organic compounds in the environment and (2) to trace the origin of organic substances. Turnover times of physical (sand < silt < clay) and chemical fractions (lignin < phospholipid fatty acids < amino sugars , sugars) are generally shorter compared to bulk soil and increase in the order given in brackets. Tracing the origin of organic compounds such as polycyclic aromatic hydrocarbons is difficult when more than two sources are involved and isotope difference of different sources is small. Therefore, this application is preferentially used when natural (e.g., C3-to-C4 plant conversion) or artificial (positive or negative) 13C labeling is used. Substanzspezifische Stabilisotopenanalyse (,13C) in der Bodenforschung Dieser Artikel fasst den Stand der Forschung bezüglich der substanzspezifischen Stabilisotopenanalyse (,13C) zusammen. Innovative Anwendungen und ein Ausblick für künftige Forschungsaktivitäten werden anhand von Fallbeispielen gegeben. Zunächst wird die ökologische Bedeutung von stabilen C-Isotopen kurz erläutert. Daran schließt sich ein methodischer Teil an, in welchem die verschiedenen Techniken gegenüber gestellt werden. Analog zu ,13C-Messungen der Feinerde mittels Elementaranalysator-Isotopenverhältnis-Massenspektrometrie können physikalisch isolierte Fraktionen (z.,B. Korngrößenfraktionen, mikrobielle Biomasse, DOC) analysiert werden. Der Schwerpunkt dieses Übersichtsartikels liegt jedoch in der Diskussion der C-Isotopensignatur chemischer Fraktionen (sog. Biomarker), welche Rückschlüsse auf Herkunft und Dynamik pflanzlicher (Pentosen, langkettige n-Alkane, Ligninphenole) und mikrobieller Rückstände (Phospholipidfettsäuren, Hexosen, Aminozucker und kurzkettige n-Alkane) sowie anderer interessanter Substanzen im Boden erlaubt wie z.,B. ,Black Carbon" und polyzyklische aromatische Kohlenwasserstoffe. Zu diesem Zweck kommen innovative Techniken zum Einsatz wie z.,B. Pyrolyse-Gaschromatographie-Isotopenverhältnismassenspektrometrie, Gaschromatographie-Verbrennungs-Isotopenverhältnismassenspektrometrie und Flüssigkeitschromatographie-Oxidations-Isotopenverhältnismassenspektrometrie. Innovative ökologische Anwendungen werden erläutert, welche sich prinzipiell in zwei Kategorien einteilen lassen: (1) Quantifizierung der Sequestrierung und des Umsatzes dieser Verbindungen in der Umwelt; (2) Untersuchung der Herkunft spezifischer organischer Substanzen. Umsatzzeiten physikalischer (Sand < Schluff < Ton) und chemischer Fraktionen (Lignin < Phospholipidfettsäuren < Aminozucker , Zucker) sind generall kleiner als jene der gesamten organischen Substanz in der Feinerde und nehmen in der in Klammern angegebenen Reihenfolge zu. Die Untersuchung der Herkunft organischer Substanzen (z.,B. polyzyklischer aromatischer Kohlenwasserstoffe) ist problematisch, weil die Unterschiede der Isotopensignatur verschiedener Quellen gering sind und meist mehr als zwei Quellen zur Isotopensignatur des untersuchten Biomarkers beitragen. Deswegen sollte die Untersuchung der Herkunft organischer Substanzen auf Tracer-Experimente beschränkt werden, wie z.,B. nach natürlicher (C3-C4-Pflanzenwechsel) bzw. künstlicher (13C-An- oder -Abreicherung) Markierung. [source]

Effects of nitrate-, ammonium-, and organic-nitrogen-based fertilizers on growth and yield of tomatoes

JOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 1 2005
Anuschka Heeb
Abstract Mineral and organic fertilizers contain different forms and amounts of nitrogen (N), which can affect yield and product quality. The aim of this study was to determine appropriate amounts of N applied as nitrate (NO), ammonium (NH), and organic N (a mixture based on chicken manure) for optimal growth and quality of tomatoes. A pot experiment with sand as substrate was established in a greenhouse with six-week-old tomato plants (Lycopersicon esculentum Mill. cv. "Armada"). Nitrogen was applied in nutrient solutions at different NO : NH ratios combined with different chloride levels (NO -dominated, NO = NH at low Cl,, NO = NH at high Cl,, and NH -dominated, respectively) or as organic N at four N-application rates (250, 500, 750, 1000 mg N plant,1 week,1). No significant differences in shoot biomass and yields of red tomatoes were observed between NO - or NH -fed plants. Nitrogen rates above 750 mg N plant,1 week,1 did not significantly increase marketable fruit yield, but enhanced shoot-biomass production. The NH -N-dominated treatments (which also had high Cl, concentrations) showed increasing incidence of blossom-end-rot (BER)-infected fruits. In the organic-N treatments, shoot-biomass production and yields were lower than in the inorganic-N treatments, but fruit quality was good with few BER-infected fruits. The results show that with a total N supply below 750 mg N plant,1 week,1, NH can be used as equivalent N source to NO, resulting in equivalent yields of marketable fruit under the conditions in this experiment. Einfluss von Nitrat, Ammonium und organischem Stickstoff auf Wachstum und Ertrag von Tomaten Mineralische und organische Dünger enthalten verschiedene Formen von und Mengen an Stickstoff (N), welche den Ernteertrag und die Produktqualität beeinflussen können. Das Ziel dieser Arbeit war es, geeignete N-Mengen , appliziert als Nitrat, Ammonium oder organischer Stickstoff , für optimales Wachstum und Qualität von Tomaten zu bestimmen. Dazu wurde mit sechs Wochen alten Tomatenpflanzen (Lycopersicon esculentum Mill. cv. "Armada") unter Gewächshausbedingungen mit Sand als Substrat ein Gefäßversuch angelegt. Die Applikation von N erfolgte in Form von Nährlösungen mit verschiedenen NO:NH -Verhältnissen, kombiniert mit unterschiedlichen Chlorid (Cl)-Konzentrationen (NO -dominiert, NO = NH bei niedrigem Cl,, NO = NH bei hohem Cl, und NH -dominiert) bzw. als organischer N. Jede dieser Behandlungen wurde mit vier verschiedenen N-Mengen angelegt (250, 500, 750, 1000 mg N Pflanze,1 Woche,1). Zwischen den mit Nitrat und Ammonium gedüngten Pflanzen konnte kein signifikanter Unterschied in Sprosswachstum und Ertrag an erntereifen Tomaten festgestellt werden. Stickstoffmengen über 750 mg N Pflanze,1 Woche,1 steigerten den Ertrag verkaufsfähiger Tomaten nicht signifikant, obwohl die Produktion an Sprossbiomasse noch anstieg. In den NH -dominiert gedüngten Gefäßen mit gleichzeitig hohen Cl-Konzentrationen in den Nährlösungen wurden häufiger Tomaten mit Blütenendfäule beobachtet. In den Behandlungen mit organischem Stickstoff waren die Sprossbiomasseproduktion und der Ertrag geringer als in den mineralisch gedüngten Behandlungen, aber die Qualität der Früchte war gut, mit nur wenigen durch Blütenendfäule geschädigten Tomaten. Die Ergebnisse zeigen, dass bei einer Stickstoffversorgung unter 750 mg N Pflanze,1 Woche,1 Ammonium anstelle von Nitrat verwendet werden kann. Im vorliegenden Versuch wurden unter diesen Bedingungen vergleichbare Erträge verkaufsfähiger Früchte erzielt. [source]

Deglaciation of the Irish Sea Basin: a critique of the glaciomarine hypothesis

JOURNAL OF QUATERNARY SCIENCE, Issue 5 2001
Danny McCarroll
Abstract The glaciomarine model for deglaciation of the Irish Sea basin suggests that the weight of ice at the last glacial maximum was sufficient to raise relative sea-levels far above their present height, destabilising the ice margin and causing rapid deglaciation. Glacigenic deposits throughout the basin have been interpreted as glaciomarine. The six main lines of evidence on which the hypothesis rests (sedimentology, deformation structures, delta deposits, marine fauna, amino-acid ratios and radiocarbon dates) are reviewed critically. The sedimentological interpretation of many sections has been challenged and it is argued that subglacial sediments are common rather than rare and that there is widespread evidence of glaciotectonism. Density-driven deformation associated with waterlain sediments is rare and occurs where water was ponded locally. Sand and gravel deposits interpreted as Gilbert-type deltas are similarly the result of local ponding or occur where glaciers from different source areas uncoupled. They do not record past sea-levels and the ad hoc theory of ,piano-key tectonics' is not required to explain the irregular pattern of altitudes. The cold-water foraminifers interpreted as in situ are regarded as reworked from Irish Sea sediments that accumulated during much of the late Quaternary, when the basin was cold and shallow with reduced salinities. Amino-acid age estimates used in support of the glaciomarine model are regarded as unreliable. Radiocarbon dates from distinctive foraminiferal assemblages in northeast Ireland show that glaciomarine sediments do occur above present sea-level, but they are restricted to low altitudes in the north of the basin and record a rise rather than a fall in sea-level. It is suggested here that the oldest dates, around 17 000 yr BP, record the first Late Devensian (Weichselian) marine inundation above present sea-level. This accords with the pattern but not the detail of recent models of sea-level change. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Filmmaker to Filmmaker: Robert Gardner and the Cinematic Process

AMERICAN ANTHROPOLOGIST, Issue 3 2007
RODERICK COOVER
Choices made in the reissue of many of Robert Gardner's groundbreaking films,including Dead Birds (1964), Rivers of Sand (1973), and Forest of Bliss (1986),on DVD demonstrate how new media tools can reinvigorate questions generated by the original works and how they can provide new insight into a filmmaker's praxis. The juxtaposition of differing media and the integration of commentary track conversations in many of these works with media makers and scholars such as Stan Brakhage, Robert Fenz, Ross McElwee, Akos Ostor, and Lucien Taylor provide unique vantage points from which to view the original documentaries and reconsider the lessons they yield. Gardner's concurrent publication of his diary and production notes in the book Impulse to Preserve (2006) contextualizes and personalizes these works, showing how they fit together in a career of innovative ethnographic production that has spanned over 50 years. [source]

Painting Sand: Nelly Sachs and the Grabschrift

THE GERMAN QUARTERLY, Issue 1 2009
Jennifer M. Hoyer
In the poem cycle Grabschriften in die Luft geschrieben (1947), Nelly Sachs (1891-1970) probes the poet's taskof and form for memorializing thedead. The poems do not conform to the traditional elements of the epitaph; rather, Sachs engages and even rejects the epitaph's task of identifying and immortalizing the dead by obscuring individual identity, then proceeding to implicate the poet, traditionally the immortalizer of the fallen, in the obliteration of the dead. Appearing at a time in which identifying and memorializing victims of the Holocaust attains critical importance, the cycle makes a significant statement regarding literature in the postwar era: poetic form can no longer function as it once did, and the role and task of the poet must be reexamined. In its refusal to identify individuals, but insistence on making that absence palpable, the cycle also complicates the ritual of memorial for the reader in a post-Holocaust setting. [source]

Figures in the Sand

ARCHITECTURAL DESIGN, Issue 5 2010
Christopher Hight
Abstract Coastal regions have become a magnet for recent development and globalisation, most conspicuously with the artificial islands off Dubai. This is a trend that has been offset by natural disasters, such as the tsunami and Hurricane Katrina. ChristopherHight and MichaelRobinson describe how the Last Resort design studio at Rice School of Architecture has made its research focus Galveston Island, a nexus of natural, cultural and economic forces. Copyright © 2010 John Wiley & Sons, Ltd. [source]

Factors affecting habitat selection in a specialist fossorial skink

BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 3 2009
AARON C. GREENVILLE
Habitat specialists maximize their fitness by using a subset of the habitats that are potentially available to them and fare poorly if they move elsewhere. The factors that constrain habitat use are diverse and often difficult to identify, but are important to distinguish if we are to understand the trade-offs that drive species to become specialists. In the present study, we investigated habitat use in a fossorial skink, Lerista labialis, and explore the factors that confine it to the crests of sand dunes in the Simpson Desert, central Australia. Models positing that L. labialis selects dune crests because of their sparse cover of vegetation, more favourable temperatures, and greater abundance of preferred prey, received no support. Instead, a model positing that dune crests provide soft and less compacted sand that facilitates movement by L. labialis, was strongly supported. Sand on the crests was consistently softer that that on the sides and swales of the dunes; the skinks preferred soft rather than hard sand for movement in captivity, and were captured more often on experimentally softened sand than on compacted sand in the field. There was no evidence that L. labialis responds to attributes of the substrate other than softness because captive animals used loose sand from the dune crests, sides, and swales equally. We suggest that the dune crest environment allows L. labialis to reduce the energetic costs of locomotion, provides priority of access to the subterranean galleries of its termite prey, and also a secure refuge from surface-active predators and extreme surface temperatures. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 531,544. [source]

Sand in the Wheels, or Oiling the Wheels, of International Finance?

BRITISH JOURNAL OF POLITICS & INTERNATIONAL RELATIONS, Issue 2 2002
New Labour's Appeal to a, new Bretton Woods'
First page of article [source]

Pyrolyse organischer Verbindungen im Mikrowellenofen

CHEMKON - CHEMIE KONKRET, FORUM FUER UNTERRICHT UND DIDAKTIK, Issue 2 2003
Arnim Lühken
Abstract DIE PYROLYSE CHEMISCHER VERBINDUNGEN wird im Chemieunterricht in unterschiedlichen Zusammenhängen thematisiert und sollte deshalb auch im Experiment nachvollzogen werden. Beispiele aus dem Bereich der Organischen Chemie sind das Cracken von Erdöl zur Gewinnung von Benzin und die thermische Zersetzung von Ethanol zur Darstellung von Ethen. In der Anorganischen Chemie sind pyrolytische Vorgänge ebenfalls von Bedeutung, werden jedoch meist als Calcinieren oder Brennen bezeichnet. Mit zunehmender Relevanz der Themen ,Umweltschutz, Stoffkreisläufe und Recycling" wurden von verschiedenen Autoren auch Experimente zur Pyrolyse von Kunststoffen und Altreifen zur Demonstration des rohstofflichen Recycling ausgearbeitet [z.B. 1-3]. In den Versuchsvorschriften zur Pyrolyse organischer Verbindungen wird das Ausgangsmaterial meist mit einem Wärmeüberträger (z.B. Sand) vermengt und über der Flamme eines oder mehrerer Gasbrenner unter Luftausschluss erhitzt. Die Thermolyse geschieht dann meist an einem ebenfalls erhitzten Festkörper-Katalysator. Als problematisch erweist sich bei der Durchführung dieser Versuchsvorschriften eine ausreichende Wärmezufuhr für die vollständige Pyrolyse der Materialmenge, da die Wärmeübertragung nicht optimal gelingt. In diesem Beitrag wird eine Methode beschrieben, deren Besonderheit zunächst die Zufuhr der zur Pyrolyse erforderlichen Wärmeenergie durch Mikrowellenstrahlung ist. Dadurch gelingt ein schnelles und gleichmäßiges Erhitzen des Pyrolysematerials. Das eingesetzte Medium zur Wärmeübertragung und dessen hohe Temperatur bedingen ein Produktspektrum, das sich überraschend von dem der klassischen Pyrolyse unterscheidet und zu interessanten Fragestellungen und didaktischen Aspekten führt. [source]

The Early and Middle Miocene transgression at the southern border of the North Sea Basin (northern Belgium)

GEOLOGICAL JOURNAL, Issue 4 2005
Stephen Louwye
Abstract The Lower,Middle Miocene Berchem Formation of northern Belgium is an essentially sandy sequence with a varying glauconite content and often abundant shelly intervals. The formation was deposited in a shallow marine environment and rests unconformably on stiff Rupelian clays or Chattian sands. The lithological recognition of the four members (Edegem Sands, Kiel Sands, Antwerpen Sands and Zonderschot Sands members) of the Berchem Formation solely based on lithological criteria proved to be difficult, especially in boreholes. The geometry of the Formation in the subsurface of northern Belgium remained largely unknown. Diverse and well preserved dinoflagellate cyst associations have been recovered from the four members in seven boreholes and two outcrops, and allow a refinement of the biostratigraphy of these deposits. A Miocene biozonation defined in mid-latitude shallow marine deposits in the Atlantic Coastal Plain of the USA (Salisbury Embayment, Maryland) is readily applicable to this material, and has led to a detailed stratigraphic assessment of each member. Three detailed profiles depicting the distribution of the biozones in the subsurface of northern Belgium allow the reconstruction of the geometry and depositional history of the Berchem Formation. The oldest Miocene deposits are of early Burdigalian age and they testify to a transgression, which invaded Belgium from a north,northwestern direction. The maximum flooding took place during early Serravallian times. The upper boundary of the formation is a major erosional surface of late Serravallian or (slightly) younger age. Copyright © 2005 John Wiley & Sons, Ltd. [source]

A Cross-Staff from the Wreck of HMS Stirling Castle (1703), Goodwin Sands, UK, and the Link with the Last Voyage of Sir Cloudesley Shovell in 1707

INTERNATIONAL JOURNAL OF NAUTICAL ARCHAEOLOGY, Issue 1 2010
B. S. Smith
Several pieces of cross-staffs have been found on the wreck of the Stirling Castle on the Goodwin Sands. One has been assembled from parts of staffs found when the wreck was first investigated, and is currently in the National Maritime Museum, Greenwich. Another part of a staff was found in 2001. It is from a cross-staff rather than a back-staff and, except for broken ends, is in good condition. The problems encountered in using such instruments are linked with the loss of Sir Cloudesley Shovell's fleet in 1707. © 2009 The Author [source]

Medical-Surgical Nursing by W. J. Phipps, J. K. Sands, J. F. Marek & M. S. Ledbetter.

JOURNAL OF CLINICAL NURSING, Issue 4 2000
1999.
[source]

Footprints in the Sands of Time: Remembering Herschel Horowitz

JOURNAL OF PUBLIC HEALTH DENTISTRY, Issue 2004
James B. Bramson DDS
No abstract is available for this article. [source]

Recent borings in limestone cobbles from Marloes Bay, southwest Wales

LETHAIA, Issue 3 2007
STEPHEN K. DONOVAN
Limestone clasts from the beach at Marloes Sands, southwest Wales, contain slender, straight to sinuous borings cross-cut by younger, clavate borings. The former were probably produced by sipunculids or polychaetes; the latter preserve shells of the boring bivalve Gastrochaena dubia (Pennant). Unusually, the calcareous linings of the clavate bivalve borings extend into many of the slender worm borings. Such linings are considered part of the hard parts of the producing bivalve, but the chance association of the two morphologies of borings has led to the lining becoming intimately associated with both of them. The modified linings of the bivalve borings have a similar morphology to the crypt of certain clavagellid bivalves, perhaps presenting an analogue for the morphology of a pre-clavagellid, boring ancestor. [source]

The Maka femur and its bearing on the antiquity of human walking: Applying contemporary concepts of morphogenesis to the human fossil record

AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2002
C. Owen Lovejoy
Abstract MAK-VP-1/1, a proximal femur recovered from the Maka Sands (ca. 3.4 mya) of the Middle Awash, Ethiopia, and attributed to Australopithecus afarensis, is described in detail. It represents the oldest skeletal evidence of locomotion in this species, and is analyzed from a morphogenetic perspective. X-ray, CT, and metric data are evaluated, using a variety of methods including discriminant function. The specimen indicates that the hip joint of A. afarensis was remarkably like that of modern humans, and that the dramatic muscle allocation shifts which distinguish living humans and African apes were already present in a highly derived form in this species. Its anatomy provides no indication of any form of locomotion save habitual terrestrial bipedality, which very probably differed only trivially from that of modern humans. Am J Phys Anthropol 119:97,133, 2002. © 2002 Wiley-Liss, Inc. [source]

Age Anaesthesia Association's 21st Anniversary Scientific Meeting in Grange over Sands, Cumbria, May 2009

ANAESTHESIA, Issue 4 2010
Article first published online: 17 MAR 2010
No abstract is available for this article. [source]

The Late-Devensian proglacial Lake Humber: new evidence from littoral deposits at Ferrybridge, Yorkshire, England

BOREAS, Issue 2 2008
MARK D. BATEMAN
Proglacial Lake Humber is of UK national significance in terms of landscape drainage and development of the British Ice Sheet (BIS) during Marine Isotope Stage 2 (MIS 2), yet it is poorly understood in terms of its dynamics and timing. Sands and gravels exposed at Ferrybridge, West Yorkshire, UK, are interpreted as part of the Upper Littoral sands and gravels related to a high-level Lake Humber, which inundated the Humber Basin to ,30 m OD during MIS 2. Excavations exposed well-rounded gravels of local origin extending downslope from the 27.5 m OD contour and interbedded sands and fine gravels, which are interpreted as the coarse littoral deposits and nearshore associated deposits. A sample from the distal sands returned an Optically Stimulated Luminescence age of 16.6±1.2 kyr, providing the first direct age for the high-level lake and for when North Sea Basin ice must have blocked the Humber Gap. An underlying sequence included a diamicton dated to after 23.3 ±1.5 kyr and before 20.5±1.2 kyr, indicating that the Late Devensian ice reached at least 15 km south of the Escrick Moraine prior to the high-level lake. Previous to both the high-level lake and this ice advance, loess found at the two sites investigated indicates a long period of loess deposition earlier in MIS 2. These new data for the history of Lake Humber are discussed in the context of ice-marginal oscillations in both the Vale of York and the North Sea Basin. [source]

Study on minute surface structures of the depressed-type early gastric cancer with magnifying endoscopy

DIGESTIVE ENDOSCOPY, Issue 3 2001
Kouji Tobita
Background: Gastric surface patterns and morphology of minute surface vessels in depressed lesions were analyzed using a magnifying endoscope with high resolving power to contribute to qualitative diagnosis of gastric cancer. Methods: Subjects were diagnosed with depressed-type early gastric cancer (pT1), there were 63 lesions, 38 differentiated-type lesions, and 25 undifferentiated-type lesions. There were also 40 benign depressed lesions found. After routine observations with an endoscope, amplifying observations of lesions were made by EG-410CR (Fuji Photo Optical; Saitama, Japan) (CR). The images were compared with macroscopic patterns and histopathological patterns of the surgical specimens and endoscopic mucosal resection specimens. Results: Surface patterns of gastric depressed lesions were classified as irregular protrusion, normal papilla, pseudopapilla and amorphia. Irregular protrusion was found only in cancerous lesions. Characteristic minute vessels were observed in amorphia. Their patterns were classified into the following six types: sand, fence, round net, flat net, branch and coil. Irregular protrusion and minute vessels in amorphia (round net, flat net, branch and coil) were specific to cancers. There was a tendency for round net and flat net patterns to be found often in differentiated cancers and for branch and coil patterns to be found often in undifferentiated cancers. Conclusion: This magnifying endoscopic classification is considered useful for the qualitative diagnosis of depressed-type early gastric cancer. [source]

Upper Pleistocene-Holocene geomorphic changes dictating sedimentation rates and historical land use in the valley system of the Chifeng region, Inner Mongolia, northern China

EARTH SURFACE PROCESSES AND LANDFORMS, Issue 11 2010
Y. Avni
Abstract This study focuses on the late Quaternary landscape evolution in the Chifeng region of Inner Mongolia, China, its relations to the history of the Pleistocene-Holocene loess accumulation, erosion and redeposition, and their impact on human occupation. Based on 57 optically stimulated luminescence (OSL) ages of loess sediments, fluvial sand and floodplain deposits accumulated on the hill slopes and floodplains, we conclude that during most of the Pleistocene period the region was blanketed by a thick layer of aeolian loess, as well as by alluvial and fluvial deposits. The loess section is divided into two main units that are separated by unconformity. The OSL ages at the top of the lower reddish loess unit yielded an approximate age of 193,ka, roughly corresponding to the transition from MIS 7 to 6, though they could be older. The upper gray loess unit accumulated during the upper Pleistocene glacial phase (MIS 4,3) at a mean accumulation rate of 0·22,m/ka. Parallel to the loess accumulation on top of the hilly topography, active fans were operating during MIS 4,2 at the outlet of large gullies surrounding the major valley at a mean accumulation rate of 0·24,m/ka. This co-accumulation indicates that gullies have been a long-term geomorphic feature at the margins of the Gobi Desert since at least the middle Pleistocene. During the Holocene, the erosion of the Pleistocene loess on the hills led to the burial of the valley floors by the redeposited sediments at a rate that decreases from 3·2,m/ka near the hills to 1,0·4,m/ka1 in the central part of the Chifeng Valley. This rapid accumulation and the frequent shifts of the courses of the river prevented the construction of permanent settlements in the valley floors, a situation which changed only with improved man-made control of the local rivers from the tenth century AD. Copyright © 2010 John Wiley & Sons, Ltd. [source]

Backshore coarsening processes triggered by wave-induced sand transport: the critical role of storm events,

EARTH SURFACE PROCESSES AND LANDFORMS, Issue 11 2010
Keiko Udo
Abstract Spatial backshore processes were investigated through field observations of topography and median sand grain size at a sandy beach facing the Pacific Ocean in Japan. A comparison of the backshore profile and cross-shore distribution of the median sand grain size in 1999 and 2004 revealed an unusual sedimentary process in which sand was coarsened in a depositional area in the 5-year period, although sediment is generally coarsened in erosional areas. In support of these observations, monthly spatial field analyses carried out in 2004 demonstrated a remarkable backshore coarsening process triggered by sedimentation in the seaward part of the backshore during a storm event. In order to elucidate mechanisms involved in the backshore coarsening process, thresholds of movable sand grain size under wave and wind actions (a uniform parameter for both these cases) in the onshore and offshore directions were estimated using wave, tide, and wind data. The cross-shore distributions of the estimated thresholds provided reasonable values and demonstrated a coarsening mechanism involving the intermediate zone around the shoreline under alternating wave and wind actions as a result of which coarse sand was transported toward the seaward part of the backshore by large waves during storms and then toward the landward part by strong onshore winds. The 5-year backshore coarsening is most certainly explained by repetition of short-term coarsening mechanisms caused by wave-induced sand transport occurring from the nearshore to the intermediate zone. Copyright © 2010 John Wiley & Sons, Ltd [source]

Effects of vegetation on channel morphodynamics: results and insights from laboratory experiments

EARTH SURFACE PROCESSES AND LANDFORMS, Issue 9 2010
Michal Tal
Abstract A series of laboratory experiments demonstrates that riparian vegetation can cause a braided channel to self-organize to, and maintain, a dynamic, single-thread channel. The initial condition for the experiments was steady-state braiding in non-cohesive sand under uniform discharge. From here, an experiment consisted of repeated cycles alternating a short duration high flow with a long duration low flow, and uniform dispersal of alfalfa seeds over the bed at the end of each high flow. Plants established on freshly deposited bars and areas of braidplain that were unoccupied during low flow. The presence of the plants had the effect of progressively focusing the high flow so that a single dominant channel developed. The single-thread channel self-adjusted to carry the high flow. Vegetation also slowed the rate of bank erosion. Matching of deposition along the point bar with erosion along the outer bend enabled the channel to develop sinuosity and migrate laterally while suppressing channel splitting and the creation of new channel width. The experimental channels spontaneously reproduced many of the mechanisms by which natural meandering channels migrate and maintain a single dominant channel, in particular bend growth and channel cutoff. In contrast with the braided system, where channel switching is a nearly continuous process, vegetation maintained a coherent channel until wholesale diversion of flow via cutoff and/or avulsion occurred, by which point the previous channel tended to be highly unfavorable for flow. Thus vegetation discouraged the coexistence of multiple channels. Varying discharge was key to allowing expression of feedbacks between the plants and the flow and promoting the transition from braiding to a single-thread channel that was then dynamically maintained. Copyright © 2010 John Wiley & Sons, Ltd. [source]