bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ordering of illite-smectite in Upper Jurassic Claystones from the North Sea
Authors: Lindgreen H. , Hansen P. L. 
Published: November 2006

AbstractUpper Jurassic claystones of Kimmeridgian-Volgian(-Ryazanian) age are the main source rocks for oil in the Central Trough, North Sea. Drill cuttings and cores from the depth interval 2368–4548 m, the interval from early-mature to peak oil generation, have been investigated by high-resolution transmission electron microscopy (HRTEM) of ion-milled rock samples, and by HRTEM and powder X-ray diffraction (XRD) of dispersed illite-smectite (I-S) mixed-layers isolated from the <0·2µm fraction. Ordering parameters were determined by XRD profile simulation. TEM on shadowed particles, combined with XRD evidence, showed that dispersed I-S consists of a mixture of 10–70 Å thick particles, whereas HRTEM showed that intact bulk rock was dominated by 50–200 Å thick particles. Disruption, possibly along smectite planes, of the larger particles in the bulk rock formed the thin particles in dispersed I-S. HRTEM showed 20 and 30 Å periodic enhancement in the contrast of lattice fringes in bulk rock samples as well as in dispersed I-S crystals. These features were interpreted as ordered I-S crystals. Indications of disintegration of larger I-S particles during sample dispersion and of the presence of ordered I-S crystals in the intact bulk rock support the layer transformation mechanism for the conversion of smectite to illite.
Origin of clay minerals in the Bonarelli Horizon (Umbrian Apennines, central Italy)
Authors: Brigatti M. F. , Poppi L. 
Published: November 2006

AbstractChemical, thermal, X-ray and statistical analyses were carried out on the clay fraction of the Bonarelli Horizon (Umbrian region, Central Italy) in order to investigate its origin. The vertical lithological sequence (organic carbon, siliceous and clay layers of varying colour and thickness) seems to change regularly, allowing the horizon to be subdivided into five sub-horizons (A to E). Sub-horizon B is clearly distinguishable from the others on the basis of the clay fractions. The presence of organic material and authigenic sulphates, constant chemical composition within a single sub-horizon, and regular repetition of the layers, show that the Bonarelli Horizon is the result of an alternation of anoxic events in a continental margin facies. A substantial contribution of volcanoclastic material is suggested for sub-horizon B.
Evidence of Ostwald ripening related recrystallization of diagenetic chlorites from reservoir rocks offshore Norway
Authors: Jahren J. S. 
Published: November 2006

AbstractChemical variations in individual chlorite crystals of diagenetic origin delineated by energy dispersive X-ray spectroscopy (EDS) in a transmission electron microscope (TEM) indicate a temperature dependent chemical zonation in each grain. Silicon decreases and Al increases with higher temperature resulting in a decreasing Si/Al ratio away from the crystal core reflecting the time and rate of the crystal growth. Chlorite particle-size distributions obtained by scanning electron microscopy (SEM) give steady state profiles which suggests that the chlorite growth is controlled by a grain coarsening process related to Ostwald ripening.
Illitization and organic maturity in Silurian sediments from the Southern Uplands of Scotland
Authors: Pearce R. B. , Clayton T. , Kemp A. E. S. 
Published: November 2006

AbstractDiscrepancies between clay mineral and organic indicators of very low-grade metamorphism have been observed from the Southern Uplands of Scotland. In the Southern Belt, I-S expandability ranges from 18–5% and chitinozoan reflectance from 0·8–2·1% R0 mean; a clear correlation exists between I-S expandability and organic maturity. At Dob's Linn in the Central Belt, I-S expandabilities range from 18–10%, and chitinozoan reflectance from 3·6–4·8% R0 mean. The results from Dob's Linn show anomalously high I-S expandabilities with respect to maturity, both in comparison with the Southern Belt and with previous work from other regions. K-feldspar is present in variable amounts in the Southern Belt, but is not detectable by XRD at Dob's Linn. Low K+ activity is believed to have resulted in a slower reaction rate at Dob's Linn, and a consequent “lag” in I-S expandability with respect to the Southern Belt.
A potassium-rich beidellite from a laterite pallid zone in Western Australia
Authors: Singh Balwant , Gilkes R. J. 
Published: November 2006

AbstractA smectite formed by weathering of mica in a laterite pallid zone at Boddington, Western Australia has been investigated by analytical electron microscopy. The evidence suggests that this mineral has the chemical composition and swelling properties of ideal beidellite but is anomalous in containing abundant non-exchangeable K. This K balances half of the layer charge that arises mostly from tetrahedral substitution of Al3+for Si4+, with the K+occupying one sixth of the sites occupied by K in mica.
Mechanisms of interaction between montmorillonite and 3-aminotriazole
Authors: Morillo E. , Pérez-Rodríguez J. L. , Maqueda C. 
Published: November 2006

AbstractThe adsorption of aminotriazole, at its solution pH, with montmorillonite saturated with different cations has been studied. A pesticide-montmorillonite complex is formed through interlamellar cations which are not displaced. Aminotriazole is situated mostly as a polarized molecule around Mg2+ and Zn2+ cations, removing a great amount of water. In Na+- and Li+-montmorillonite, the pesticide remains as a non-polarized molecule, hydration water being retained in the interlamellar space; the pesticide is coordinated to interlamellar cations through water bridges. For all samples a proportion of cationic aminotriazole is also adsorbed, the amount being greater with increasing polarizing power of the interlamellar cation; consequently, in Fe3+-montmorillonite all the aminotriazole adsorbed is in the cationic form.
On the genesis and composition of natural pyroaurite
Authors: Taylor R. M. , Hansen H. C. B. , Stanger G. , Bender Koch C. 
Published: November 2006

AbstractSamples of the mineral pyroaurite, formed from the weathering of partially serpentinised harzburgite (olivine + pyroxene) were found in an arid region of the Sultanate of Oman. These were either golden or silver in colour depending on the horizon from which they were derived. Chemical analysis showed that the colour variation was primarily due to the differing conditions in the hydrological environment. The golden colour was attributed to small Fe(III) oxide particles detected by Mössbauer spectroscopy. In addition, the samples were examined by X-ray diffraction, scanning electron microscopy, and glycerol intercalation. These results were compared with a synthetic pyroaurite sample prepared under conditions (previously reported) similar to those in nature. These conditions are shown to approximate to those found in the hydrological environment in the zones of the natural pyroaurite formation.
The use of glycerol intercalates in the exchange of CO32−with SO42−, NO3−or Cl−in pyroaurite-type compounds
Authors: Hansen H. C. B. , Taylor R. M. 
Published: November 2006

AbstractStrongly held carbonates anions in the interlayer region of pyroaurite-type compounds, [MlII1−xM2IIIx(OH)2]x+[(CO3)x/2yH2O]x−(x= 0·15−0·44), can be relatively easily exchanged by other anions such as NO3−, Cl−or SO42−dissolved in heated glycerol. Some Fe(III) of pyroaurite is reduced to Fe(II) by the glycerol treatment. If pyroaurite is treated with glycerol in the absence of dissolved anions or with glycerol vapour at 120°C, glycerol becomes intercalated in the interlayers. In all examples the interlayer CO32−is partially or completely lost as CO2. In aqueous salt solutions a glycerol intercalated form allows other anions to substitute in the interlayer. Expansion in thec-axis direction following glycerol treatment depends on (1) the method of glycerol treatment, (2) the trivalent metal in the octahedral sheet, and (3) the interlayer anions. Heated glycerol causes a different expansion to that produced by its vapour phase at 120°C. The variation ind(003) follows the series: hydrotalcitevap. > pyroauritevap.> hydrotalciteliquid> pyroauriteliquid> SO42−-pyroauritevap. > SO42−-hydrotalcitevap., where liquid refers to glycerol used at 160–180°C and vap. refers to glycerol vapour at 120°C Carbonate-free, glycerol-intercalated pyroaurite compounds may serve as re-usable anion absorbers. Glycerol intercalates of pyroaurite-type compounds may also be useful to study and identify stacking sequences and interlayer compositions in these minerals.
A mineralogical and geochemical approach to establishing a sedimentary model in a passive continental margin (Subbetic Zone, Betic Cordilleras, SE Spain)
Authors: Ortega-Huertas M. , Palomo I. , Moresi M. , Oddone M. 
Published: November 2006

AbstractThe spatial and vertical distributions of six clay mineral assemblages were identified in the pelagic marls and marly limestones and in the Ammonitico Rosso of the Lower Jurassic in the Betic Cordilleras (SE Spain). The six assemblages contain varying proportions of illite, kaolinite, chlorite, smectite and mixed-layer illite-smectite. The clay mineralogy and the geochemical data, particularly for the rare earth elements, indicate that the sediments were deposited in a pelagic environment influenced by a nearby continent. The source areas were many and lithologically varied. Clay mineralogy and geochemistry are shown to be most useful in the reconstruction of the palaeogeography of a basin in a passive continental margin.
Crystallochemistry, properties and organization of soil clays derived from major sedimentary rocks in France
Authors: Robert M. , Hardy M. , Elsass F. 
Published: November 2006

AbstractThe nature, crystallochemistry, organization and surface properties of soil clays derived from the most representative sedimentary formations of France are described, using qualitative and quantitative mineralogical methods and high resolution transmission microscopy (HRTEM). The main results show that soil clays differ significantly from reference clays. Even when 2:1 phyllosilicates are dominant, the clays always contain multimineral phases. The smectitic component is dioctahedral and of beidellite type. Soil clay organization is specific: all the clay particles have a short lateral extension and few layers (mean 5 layers, and even mono-layers occur). The superposition of such small particles leads to the formation of what are called “texturally interstratified minerals” which are dominant in soil clays. Exchange and surface properties (high ratio of external surface to total surface area), are related to clay organization.
Concentration of iron oxides from soil clays by 5 m NaOH treatment: the complete removal of sodalite and kaolin
Authors: Singh Balwant , Gilkes R. J. 
Published: November 2006

AbstractThe Kämpf & Schwertmann (1982) procedure for concentrating iron oxides in soil clays by dissolution of kaolin and gibbsite by boiling for 1 h in 5 m NaOH may not dissolve all kaolin, and also results in the precipitation of sodalite. For the complete dissolution of kaolin in kaolin-rich soil clays a boiling time of 2 h in 5 m NaOH was required. The large amounts of sodalite produced were not removed by the prescribed single wash in 0·5 m HCl. Oxalate soluble Al contents of iron oxide concentrates were sometimes very high and dithionite Fe contents were very low both in concentrates containing sodalite, and in those for which sodalite was not detected by XRD, but where a previously unsuspected amorphous sodalite-like phase may have been present. Complete removal of precipitated sodalite was achieved by two extractions with 0·5 m HCl at 25°C for 20 min. This modified procedure does not alter the Al-substitution and crystal size of goethite, hematite and maghemite as determined by XRD measurements.
Thermogravimetric study of the desorption of cyclohexylamine and pyridine from an acid-treated Wyoming bentonite
Authors: Breen C. 
Published: November 2006

AbstractFour 15 g samples of an unsedimented Wyoming bentonite were treated with 200 cm3 of 0·025, 0·050, 0·100 and 0·250 mol dm−3 H2SO4 for 1 h at room temperature (samples I–IV, respectively). Three further 15 g samples were treated with 200 cm3 of 50% (v/v) H2SO4 for 1 h at 20°C (sample V), and 1 and 2 h under reflux (samples VI and VII, respectively). X-ray fluorescence and diffraction studies revealed that only samples VI and VII suffered any substantial structural attack. The resulting acidity of the clays, determined by cyclohexylamine desorption, indicated that sample V contained the largest number of protons at 0·59 mmol H+ (g clay)−1. Sample V was also the most efficient catalyst for the dehydration and etherification of hexan-1-ol, giving a combined product yield of 17·0% after 2 h reflux in neat reactant. The parent bentonite and samples I and II showed no discernible catalytic activity despite measured acidities of 0·1, 0·24 and 0·34 mmol H+ (g clay)−1. In contrast samples III and IV gave combined product yields of 4·5 and 11·0%, respectively, which correlated well with the measured acidities of 0·38 and 0·48 mmol H+ (g clay)−1. Samples VI and VII, prepared by reflux in acid, contained 0·3 and 0·1 mmol H+ (g clay)−1, respectively, and gave combined product yields of 13·0 and 6·0%.
Thermogravimetric and infrared study of the desorption of butylamine, cyclohexylamine and pyridine from Ni- and Co-exchanged montmorillonite
Authors: Breen C. 
Published: November 2006

AbstractThe acidity of Ni2+- and Co2+-exchanged montmorillonite has been probed using the diagnostic bases n-butylamine, cyclohexylamine and pyridine. Derivative thermograms for the desorption of pyridine from Ni2+- and Co2+-exchanged montmorillonite exhibited strong maxima at 40°, 90° and 360°C together with a weak maximum near 170°C The desorption maximum at 360°C is usually attributed to desorption of base from Bronsted acid sites. However, IR spectra of pyridine adsorbed on Ni2+- and Co2+-exchanged montmorillonite, at 250°C were dominated by intense bands near 1450 and 1607 cm−1 which are diagnostic of Lewis-bound pyridine. Consequently, the desorption maximum at 360°C must, in this instance, be attributed to desorption of pyridine from Lewis acid centres. Other bases, including cyclohexylamine and butylamine, also desorb at temperatures which have previously been attributed to the desorption of protonated base. Ni2+- and Co2+-exchanged clay contained predominatly Lewis acid or electron accepting sites, which is in marked contrast to the behaviour of trivalent cation exchanged clays.
Non-crystalline hydrous feldspathoids in Late Permian carbonate rock
Authors: Bender Koch C. 
Published: November 2006

AbstractThe EDTA-insoluble residues from five samples (two from the oolitic shoal facies and three from the lagoonal facies) of the Late Permian Ca-2 unit (Zechstein) have been investigated by X-ray diffraction, infrared spectroscopy, and scanning and transmission electron microscopy with energy dispersive X-ray analysis (EDXA). The results show that spheres of non-crystalline hydrous feldspathoids (with Al/Si molar ratio between 1·5 and 2·2) dominate the residues of samples from the oolitic shoal facies. Samples from the lagoonal facies are dominated by crystalline material (muscovite and quartz), but two of the samples contain a small number of spheres. Analyses of these samples by selective area diffraction and EDXA revealed the presence of small amounts of non-crystalline hydrous feldspathoids with Al/Si molar ratio between 0·1 and 1·9.
Effects of dry grinding on two kaolins of different degrees of crystallinity
Authors: Gonzalez Garcia F. , Ruiz Abrio M. T. , Gonzalez Rodriguez M. 
Published: November 2006

AbstractGrain-size distribution, specific surface, thermal analysis, electron microscopy and X-ray diffraction were used to study the effect of dry grinding on the structure and properties of two kaolins of different degree of crystallinity. Grinding caused particles to fragment and resulted in the formation of stable large spheroidal aggregates of fine particles. These two processes were not clearly separated by a specific grinding time, but occurred in parallel shortly after grinding was started, although aggregate formation persisted at longer grinding times. The variation in the specific surface area during grinding was found to be dependent on these two processes and on the particle size and crystallinity of the initial kaolin. DTA and XRD data and the amount of water released at different temperatures revealed grinding to gradually destroy the kaolinite structure and cause the loss of hydroxyl ions and the formation of others that were subsequently removed at low and medium temperatures. An explanation for the process whereby the new hydroxyl ions are formed is provided.
Additive-free Hydrothermal Synthesis of High Aspect Ratio ZnO Particles from Aqueous Solution
Authors: Elen Ken , Van Bael Marlies K , Van den Rul Heidi , D’Haen Jan , Mullens Jules 
Published: November 2006

Abstract
In this work, a new hydrothermal process is described, in which, for the first time, an aquatic Zn2+ precursor is used for the synthesis of high aspect ratio ZnO particles, without the presence of any organic additive. Characterization of the particles is carried out by XRD, TEM, and SAED. Also the influence of different reaction times and of another reaction medium on the morphology and the dimensions of the rods is investigated.
Improving MEA Durability by Using a Catalyst with a Small Number of Functional Groups on Its Surface
Authors: Tanuma Toshihiro , Terazono Shinji 
Published: November 2006

Abstract
In order to improve the durability of MEAs, surface functional groups on catalysts were focused. It was found that functional groups such as hydroxy and carboxyl groups are responsible for the OCV degradation of MEAs. By applying a heat-treated catalyst, which has a small number of functional groups on its surface, to both cathode and anode of an MEA, the OCV durability was drastically improved.
Synthesis of 1,1′-Binaphthyl-2,2′-diyl Phosphoroselenoic Amides and Their Conversion to Optically Pure Phosphoramidites
Authors: Murai Toshiaki , Inaji Shinsuke , Morishita Ken , Shibahara Fumitoshi , Tokunaga Makoto , Obora Yasushi , Tsuji Yasushi 
Published: November 2006

Abstract
Optically pure phosphoroselenoyl chloride was reacted with racemic amines to give phosphoroselenoic amides as two diastereomeric mixtures in high yields. The diastereomeric mixtures were separated by fractional recrystallization or by chromatography. Extrusion of the selenium atom from the separated amides led to diastereomerically pure phosphoramidites. The ability of the obtained amidites to act as optically active ligands was tested in the hydrogenation of an imine.
Hydrophobic Functionalization of Mesoporous SBA-15 with Polyisoprene as a New Drug Delivery System
Authors: Zhou Zhengyang , Zhu Shenmin , Zhang Di , Zhou Zhiping 
Published: November 2006

Abstract
A novel delivery carrier system has been successfully conducted based on the ordered mesoporous silica SBA-15 with hydrophobic polyisoprene polymerized in the pores network. It is interesting to find that the result system still holds a relatively large pore size (6.5 nm) and pore volume (0.72 cm3 g−1), which will benefit for the storage of drugs with relatively large molecules.
Protecting Human Subjects of Research: An Analysis on Proposed Amendments to HEW Policy
Authors: de Sola Pool Ithiel 
Published: November 2006

Editor's Note: The Department of Health, Education and Welfare has prepared amendments to regulations governing research on human subjects. The regulations were established in response to recommendations from the National Commission for the Protection of Human Subjects of Biomedicai and Behavioral Research. These regulations are implemented by the institutional review boards established by colleges, universities and research institutes. The intent of the proposed amendments is admirable: to reduce the categories of research coming under federal control and review. But specific amendments could impose restrictions and difficulties upon political scientists conducting research projects or teaching their students to conduct research.The Association's Council's concerns about the proposed regulations was expressed in this resolution passed on August 30:While endorsing the important goal of protecting human subjects of research from abuse or injury, the APSA opposes any existing or proposed regulations or procedures relating to institutional review boards that would represent a threat to academic freedom or research or freedom of speech. The Council asks the Executive Director, in cooperation with other social science associations and higher education associations to prepare and present analysts of the implications of existing and proposed research regulations for political scientists and other social scientists.Ithiel de Sola Pool has prepared the following analysis of the proposed regulations in order to inform colleagues of their possible impact. Political scientists who share his concerns are invited to write to the Executive Director of the APSA and join in forming a Committee of Concern about Institutional Review Board Practices by writing to: Ithiel de Sola Pool, 105 Irving Street, Cambridge, Massachusetts 02138.The “Proposed Regulations Amending Basic HEW Policy for Protection of Human Research Subjects” which were published in the Federal Register of Tuesday, August 14, 1979, represent a substantial improvement over previous rules and draft rules, but are still grossly improper and unconstitutional.
Scattering properties for a pair of Schrödinger type operators on cylindrical domains
Authors: Melgaard Michael 
Published: November 2006

Abstract
Strong asymptotic completeness is shown for a pair of Schrödinger type operators on a cylindrical Lipschitz domain. A key ingredient is a limiting absorption principle valid in a scale of weighted (local) Sobolev spaces with respect to the uniform topology. The results are based on a refined version of Mourre’s method within the context of pseudo-selfadjoint operators.
SIRE-1, A putative plant retrovirus is closely related to a legume TY1-copia retrotransposon family
Authors: Pearce Stephen 
Published: November 2006

AbstractSIRE-1 is a potential soybean retrovirus which has a gene order similar to Ty1-copia retrotransposons but also contains an envelope-like open reading frame (ORF), which is characteristic of retroviruses. PCR and Southern analysis reveals that SIRE-1 is closely related to a legume-wide family of envelope-lacking Ty1-copia group retrotransposons which suggests that SIRE-1 was formed by the recent acquisition of an envelope gene by a Ty1-copia retrotransposon.