bluuebunny/crossref_metadata_2025 huggingface dataset:
Nanoindentation Studies on Amorphous, Nanoquasicrystalline and Nanocrystalline Zr80Pt20 and Zr75Pd25 Alloys
Authors: Bhatt Jatin , Pabi S. K. , Murty B. S.
Published: November 2006

Nanoindentation studies on rapidly solidified Zr80Pt20 and Zr75Pd25 binary alloys with nanocrystalline, nanoquasicrystalline, and amorphous microstructures are reported. The results indicate that the hardness and elastic modulus are the highest
for a mixture of amorphous and nanoquasicrystalline state among the various microstructures studied. Nanoquasicrystalline phase has high hardness and elastic modulus in comparison to amorphous and nanocrystalline phases. The hardness to modulus ratio is close to 0.1 in both the alloys, irrespective
of the phase/phase mixture studied indicating that the bonding in these alloys is of covalent nature. In Zr80Pt20, all the phases/phase mixtures have higher hardness and modulus in comparison to similar microstructures in Zr75Pd25 due to higher bond
energies caused by more negative heat of mixing in the former case.
Sputter Deposition of Self-Organized Nanoclusters Through Porous Anodic Alumina Templates
Authors: Gohil Smita , Chandra Ramesh , Chalke Bhagyashree , Bose Sangita , Ayyub Pushan
Published: November 2006

Silver nanoparticles were sputter deposited through self organized hexagonally ordered porous anodic alumina templates that were fabricated using a two-step anodization process. The average pore diameter of the template was 90 nm and the interpore spacing was 120 nm. Atomic force microscope
studies of the sputter-deposited silver nanoparticle array on a Si substrate indicate an approximate replication of the porous anodic alumina mask. The nature of the deposition depends strongly on the process parameters such as sputtering voltage, ambient pressure and substrate temperature.
We report a detailed study of the sputtering conditions that lead to an optimal deposition through the template.
Pattern Formation in Nanoporous Titania Templates
Authors: Richter C. , Wu Z. , Menon L.
Published: November 2006

We have carried out a systematic investigation into the formation of nanoscaled patterns in titania (TiO2) templates under dc anodization of Ti in HF acid. At lower acid concentrations (around 0.5 wt% HF) either pores or tubes form at the surface of anodized titanium foil.
The pores or nanotubes are separated from the bottom Ti layer by a thin barrier layer of TiO2. The critical voltage where the transition from pores to tubes occurs has been determined. It is observed that the transition voltage shift towards higher voltages as acid concentration
is increased, with pore formation disappearing altogether at high acid concentrations. We have also carried out a systematic investigation into the dependence of pore and tube parameters on the applied dc anodization voltage. Our results indicate that the barrier layer thickness, pore and
tube length increase as a function of applied voltage.
In Vitro and In Vivo Toxicity of CdTe Nanoparticles
Authors: Zhang Yongbin , Chen Wei , Zhang Jun , Liu Jing , Chen Guangping , Pope Carey
Published: November 2006

Cadmium telluride (CdTe) nanoparticles exhibit strong and stable fluorescence that is attractive for many applications such as biological probing and solid state lighting. The evaluation of nanoparticle toxicity is important for realizing these practical applications. However, no systematic
studies of CdTe nanoparticle toxicity have been reported. We investigated and compared the size- and concentration-dependent cytotoxicity of CdTe nanoparticles in human hepatoma HepG2 cells using the MTT assay. CdTe nanoparticles elicited cytotoxicity in a concentration- and size-dependent
manner, with smaller-sized particles exhibiting somewhat higher potency. Lesser cytotoxicity of partially purified CdTe-Red particles (following methanol precipitation and resuspension) suggested that free cadmium ions may contribute to cytotoxicity. We also evaluated the acute toxicity of
CdTe-Red particles following intravenous exposure in male rats (2 μmol/kg). Few signs of functional toxicity or clinical (urinary or blood) changes were noted. Interestingly, motor activity was transiently reduced (2 hours after treatment) and then significantly increased at a later
timepoint (24 hours after dosing). These studies provide a framework for further characterizing the in vitro and in vivo toxic potential of different types of CdTe nanoparticles and suggest that the nervous system may be targeted by these nanoparticles under some conditions.
Synthesis of Nanocrystalline (Co, Ni)Al2O4 Spinel Powder by Mechanical Milling of Quasicrystalline Materials
Authors: Yadav T. P. , Mukhopadhyay N. K. , Tiwari R. S. , Srivastava O. N.
Published: November 2006

In the present study, attempts have been made to synthesize the nano-crystalline (Co, Ni)Al2 O4 spinel powders by ball milling and subsequent annealing. An alloy of Al70Co15Ni15, exhibitingthe formation of a complex intermetallic
compound known as decagonal quasicrystal is selected as the starting material for mechanical milling. It is interesting to note that this alloy is close to the stoichiometry of aluminum and transition metal atoms required to form the aluminate spinel. The milling was carried out in an attritor
mill at 400 rpm for 40 hours with ball to powder ratio of 20 : 1 in hexane medium. Subsequent to this annealing was performed in an air ambience for 10, 20, and 40 h at 600°C in side the furnace in order to oxidize the decagonal phase and finally to form the spinel structure. The X-ray
diffraction (XRD) and transmission electron microscopy (TEM) confirmed the formation of nano-sized decagonal phase after milling and then (Co, Ni)Al2O4 spinel type phase after annealing. The XRD studies reveal the lattice parameter to be 8.075 Å and the lattice
strain as 0.6%. The XRD and TEM explorations of spinel phase indicate the average grain size to be ∼40 nm.
Facile Fabrication of Magnetic Nanocomposites of Ordered Mesoporous Carbon Decorated with Nickel Nanoparticles
Authors: Cao Yulin , Cao Jieming , Zheng Mingbo , Liu Jinsong , Ji Guangbin , Ji Hongmei
Published: November 2006

A magnetic nanocomposite of ordered mesoporous carbon (CMK-3) decorated with nickel nanoparticles was synthesized successfully by a simple chemistry method. Nickel nanoparticles were prepared and uniformly supported on ordered mesoporous carbon CMK-3 by reduction route with CMK-3 as
a reducing agent at 673 K. The Ni/CMK-3 composite materials were characterized by powder X-ray diffraction, nitrogen sorption, and transmission electron microscopy. As-prepared nickel nanoparticles supported on CMK-3 were crystalline with a face-center-cubic phase and a size distribution ranging
from 10 to 60 nm. The BET special surface area and pore volume of Ni/CMK-3 were as high as 797 m2 g−1 and 0.72 cm3 g−1, respectively. The formation mechanism of the nickel nanoparticles outside the surface of CMK-3 was preliminarily discussed.
The hysteresis loops of the CMK-3 decorated with nickel nanoparticles were measured by vibrating sample magnetometer (VSM), and the results showed that the composite was ferromagnetism with the saturated magnetization of 15 emu/g, and the coercivity value of 214 Oe. Furthermore, the application
of Ni/CMK-3 as magnetically separable adsorbent for vitamin B2 was primarily examined in this study.
Catalyst-Free Template-Synthesis of ZnO Nanopetals at 60 °C
Authors: Pan Hui , Feng Yuan Ping , Lin Jianyi , Liu Chuan Jun , Wee Thye Shen
Published: November 2006

We report successful growth of a new form of ZnO nanostructures, ZnO nanopetals at low temperature. This two-dimensional nanostructure is morphologically different from nanowalls. The flat and circularly edged nanopetals intersect each other. The thickness of nanopetals is uniform and
about 30 nm. The nanostructure was produced using a simple catalyst-free chemical method based on anodic aluminum oxide (AAO) template. The growth temperature was 60 °C which is much lower than that required for growing ZnO nanowalls. The formation of the nanopetal network was induced
by the porous alumina network on the surface of the AAO template.
Synthesis of Carbon–Nitrogen Nanostructures by Hot Isostatic Pressure Apparatus and Their Field Emission Properties
Authors: Lee Yang Doo , Blank V. D. , Batov D. V. , Buga S. G. , Lee Yun-Hi , Nahm Sahn , Ju Byeong-Kwon
Published: November 2006

Carbon–nitrogen (CN) nanofibers were synthesized in argon–nitrogen gas mixture at 75 MPa by high isostatic pressure (HIP) apparatus using a graphite resistive heater. The CN nanofibers were grown in random with the diameter of about 200 nm and the length over 5 μm.
The structures obtained can be divided bamboo-like, spring-like, and bead necklace-like CN nanofibers. The nitrogen content of up to 8.4% was found in CN nanofibers by EELS analysis. Field emission results showed that the density of field emitters and the field enhancement factors changed
by surface treatments and that CN nanofibers contained glass frit. The screen-printed CN nanofiber had a turn-on field of 2 V/μm.
Co-occurrence of depressive moods and delinquency in early adolescence: The role of failure expectations, manipulativeness, and social contexts
Authors: Overbeek Geertjan , Biesecker Gretchen , Kerr Margaret , Stattin Håkan , Meeus Wim , Engels Rutger C.M.E.
Published: November 2006

This study examined the co-occurrence of depression and delinquency in early adolescents, focusing on longitudinal associations with failure expectations and manipulativeness, and on perceptions of relationships with parents, school and teachers, and peers. Data were used from 1,059 Swedish adolescents aged 13 to 15, who participated in 2 waves (T1–1998; T2–2000) of an ongoing longitudinal research. Results showed that depression and delinquency co-occurred in about 9% of respondents, and that depression and delinquency followed separate developments throughout early adolescence. Development of co-occurring depression and delinquency was positively linked to a later constellation of high failure expectations and manipulativeness across a 2-year period. Additionally, the development of combined failure expectations and manipulativeness was positively linked to a later co-occurrence of depression and delinquency across a 2-year period. Further, the cooccurrence of depression and delinquency was predicted by lower-quality relationships with parents and negative attitudes towards school and teachers, whereas a constellation of high failure expectations and manipulativeness was linked to earlier negative interactions with parents and feeling isolated from peers.
Eye blink startle responses in behaviorally inhibited and uninhibited children
Authors: van Brakel Anna M.L. , Muris Peter , Derks Wendy
Published: November 2006

The present study examined the startle reflex as a physiological marker of behavioral inhibition. Participants were 7to 12-year-old children who had been previously identified as inhibited or uninhibited as part of an ongoing longitudinal study on the role of behavioral inhibition in the development of anxiety disorders. Analysis of their scores on the Behavioral Inhibition Scale revealed that the children were stable in their behavioral inhibition categorization as compared to the beginning of the longitudinal study. An experiment was carried out to study startle modulation effects in response to novel and familiar pictures of threatening and non-threatening facial expressions in inhibited and uninhibited children. The main results can be summarized as follows. To begin with, no modulation effect was found. That is, children did not show the expected (adult-like) startle facilitation while viewing unpleasant pictures. Second, a habituation effect was found: that is, during the testing phase children responded more intensely to the first block of slides than to the second block of slides (irrespective of slide content). Third, unexpectedly behaviorally inhibited children displayed smaller eye blink magnitudes in response to novel slides than uninhibited children. Fourth and finally, no meaningful differences were found in the patterns of startle responses of both genders.
Proactive and reactive aggression in childhood and adolescence: A meta-analysis of differential relations with psychosocial adjustment
Authors: Card Noel A. , Little Todd D.
Published: November 2006

Aggressive behavior in childhood has long been separated into that which is proactively motivated and that which is reactive. We report a meta-analytic review of the existing empirical literature that examines the associations of each type of aggression with six indices of psychosocial adjustment: internalizing problems, emotional dysregulation and ADHD-type symptoms, delinquent behaviors, prosocial behavior, sociometric status, and peer victimization. Even though not detectable in most single studies, meta-analytic combination revealed that reactive aggression was more strongly related to most of the indices of adjustment than was proactive aggression. This difference was small, however, and we argue that the difficulty in detecting differential correlates is due to the high intercorrelation between the functions of aggression, which appears to be an artifact of traditional measurement procedures. It is recommended that future research use measures that provide distinct assessment of the functions in order to more clearly distinguish the correlates of proactive and reactive aggression.
Provincial Governors and the Absolute State: Piedmont 1713-48
Authors: Storrs Christopher
Published: November 2006

Most studies of absolutism, particularly in Piedmont (and more broadly the Savoyard state of which it was part) focus on the emergence of intendants as an agent of the centralizing state. However, this completely ignores the role of the provincial governors. This article therefore looks in closer detail than has been done hitherto, at the role, recruitment, remuneration and social background of the provincial governors of Piedmont as an important but still rather obscure period of Savoyard state formation. Provincial governors were essentially soldiers in a highly militarized state, which was one reason for their prominent role, and they fulfilled many of the absolutist or centralizing functions (monitoring, punishing) usually attributed to other agents of the state. Among their responsibilities was watching over the local nobility. The modus operandi of governors reflected a growing formalization of practice within the Savoyard state. At the same time, however, governors sometimes clashed with the other agents of that state. In terms of remuneration, governors scored much higher than did intendants. Governors were also of more exalted social origin. More work needs to be done on the provincial governors of the early modern Savoyard state but clearly they cannot be ignored as an instrument of that state, or as an indicator that the older elite successfully inserted itself into that structure to its own advantage.
The Culture of Democracy and Bolivia’s Indigenous Movements
Authors: Albro Robert
Published: November 2006

This article describes the participation of Bolivia’s indigenous movements in encompassing popular protest coalitions of the last five years. Pointing to the importance of cultural heritage in current social movement efforts to revitalize Bolivian democracy, this argument examines the importance of the ‘terms of recognition’ in the negotiation of the very meaning of democratic participation, between the traditional political class and popular protesters, but also within protesting coalitions. As both indigenous and popular traditions of struggle increasingly make common cause, Bolivia’s indigenous movements are providing the cultural resources that frame the terms of popular protest. At the same time, the terms of indigenous identity are also changing form, becoming more available to growing urban-indigenous and non-indigenous popular social sectors now willing to claim or reclaim an indigenous heritage. This article also explores key transnational and national networks now involved in this transformation of the terms of indigenous cultural heritage, making it the basis of an alternative democratic public in Bolivia.
Life in the shadow of the media
Authors: Hodgetts Darrin , Hodgetts Andrea , Radley Alan
Published: November 2006

Media images pervading everyday life often reproduce inequitable social relations that adversely affect the lives of vulnerable people. This article explores the influence of media representations of homelessness as a source of characterizations that are used by homeless people when representing themselves. To do this, it draws on life narrative interviews, photographic exercises and phogo-based discussions with 12 single rough sleepers from London. It documents how participants both reproduce common media storylines foregrounding their differences from housed people and emphasizes aspects of their lives that do not feature in media portrayals, but which invoke their `normality'.
On the ground and off
Authors: Heiskanen Benita
Published: November 2006

In the United States, prizefighting carries deep-seated meanings as an ethnically and racially delineated, class-based and gendered practice. At present, the sport is characterized by its ongoing ‘latinization’ corresponding to Latinos’ integration endeavors in urban USA. This article examines boxing as a locus for identity formations. Based on four years of ethnographic fieldwork with a community of Latino prizefighters in Austin, TX between 2000 and 2004, the research draws on life-story interviews conducted with the boxers, while their experiences are situated within a theoretical framework of the body in space and place. The fieldwork brings the research ‘onto the ground’ to the actual sites-such as the boxing gym, the weigh-in and the competition venue-where the athletes conduct their occupation on a daily basis. As professional boxing determines these worker-athletes’ physical prowess, it also shapes their identities, day-to-day survival and their very mode of being in the world.
Swelling behaviour of montmorillonite by poly-6-amide
Authors: Fukushima Y. , Okada A. , Kawasumi M. , Kurauchi T. , Kamigaito O.
Published: November 2006

Intercalated compounds of montmorillonite and poly-6-amide were prepared by heating mixtures of ɛ-caprolactam and 5, 10, 15 and 30 wt% of montmorillonite, cation-exchanged with NH3+(CH2)11COOH, at 250°C in a nitrogen atmosphere, and examined by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), gel permeation chromatography (GPC) and elemental analysis. ɛ-caprolactam was polymerized to poly-6-amide by the heat treatment. The mean number-average molecular weight decreased from 3·6 × 104 to 0·8 × 104 with increasing montmorillonite content. TEM showed that considerable swelling had taken place subsequent to polymerization and that the clay layers were uniformly distributed in the final clay/poly-6-amide products. Both XRD and TEM showed that the basal spacing of the compound increased from 51 Å to 210 Å with increasing polyamide content. The driving force for the swelling was considered to be a combination of the polymerization energy of ɛ-caprolactam and the attractive interaction between the interlayer cation and ɛ-caprolactam.
Conductimetric investigations on the dissolution of metakaolinite in dilute hydrofluoric acid. Structural implications
Authors: Murat M. , Driouche M.
Published: November 2006

Abstarct

Conductimetric curves based on dissolution in dilute HF of a series of metakaolinite samples prepared by thermal dehydroxylation of kaolinite in air from 500°C to 987°C, have been interpreted in terms of (i) short-time conductivity variation, and (ii) specific initial dissolution rate (rsi). The first parameter has been correlated with a disorganization factor (Fd, equal to unity for an entirely amorphous silica-alumina mix) which does not exceed 0·52 for metakaolinite and, like rsi, reaches a maximum for samples prepared at about 720–750°C. These results, which agree with other data obtained by calorimetry and infrared spectroscopy, show that metakaolinite is never entirely amorphous and has a degree of disorder which varies with the conditions of preparation, and increases for samples which have been mechanically treated by grinding.
Formation of illitic minerals at surface temperatures in Purbeckian sediments (Lower Berriasian, Swiss and French Jura)
Authors: Deconinck J. F. , Strasser A. , Debrabant P.
Published: November 2006

The clay-mineralogical assemblages of Purbeckian carbonate sediments of the Swiss and French Jura Mountains are often composed of illite and interstratified illite-smectite. These illitic minerals occur mainly in thin layers of green marls which show evidence of subaerial exposure and mark the top of shallowing-upward sequences. X-ray diffraction, chemical and thermal analyses coupled with transmission electron microscopy suggest that the Purbeckian illitic minerals replaced smectite in intermediate continental-marine environments. The transition from smectite to illite and interstratified illite-smectite probably resulted from repeated cycles of wetting by marine waters and subsequent drying in hypersaline environments, under a hot Purbeckian climate.
Evidence for the multiphase nature of bentonites from Mössbauer and EPR spectroscopy
Authors: Goodman B. A. , Nadeau P. H. , Chadwick J.
Published: November 2006

Mössbauer spectra of several smectites demonstrate the existence of at least three phases with distinct Fe populations: (i) a component with very low Fe content (< 1%), which shows slowly-relaxing paramagnetic hyperfine structure at both 4·2 K and 77 K; (ii) a component with intermediate Fe content (∼ 1–10%) which is seen as doublets in the spectra at 4·2 K, 77 K and ambient temperature; (iii) an Fe-rich phase (> 30% Fe), which shows magnetic ordering at 4·2 K and 77 K. These data are consistent with components (i) and (ii) corresponding to Fe incorporated in aluminosilicate structures from distinct phases, whereas (iii) is characteristic of an iron oxide phase, probably goethite in most cases. These conclusions are supported by EPR measurements which show magnetically-dilute Fe in more than one type of structural environment plus an additional component with magnetically-interacting ions.
Identification of oxide impurity phases and distribution of structural iron in some diagenetic illitic clays as determined by Mössbauer spectroscopy
Authors: Goodman B. A. , Nadeau P. H.
Published: November 2006

Seven diagenetic illitie clays have been investigated by Mössbauer spectroscopy to characterize the forms of iron. Four specimens had measurable amounts of iron oxide impurity phases, accounting for up to ∼95% of the total Fe. Goethite, microcrystalline and probably aluminous, was identified as the oxide phase in three of these samples, the other containing hematite. This latter sample was also the only one which had tetrahedral Fe(III). Five of the samples contained measurable amounts of Fe(II), but the aluminosilicate Fe was present largely as 6-coordinated Fe(III) which had two distinctly different sets of parameters. These results are discussed in terms of the structural properties of illites.
The acidity of trivalent cation-exchanged montmorillonite. II. Desorption of mono- and di-substituted pyridines
Authors: Breen C.
Published: November 2006

Temperature programmed desorption (TPD) and IR spectroscopy were used to examine the desorption of pyridine, 2-methyl-, 4-methyl- and 2,6-dimethylpyridine from Al3+- and Cr3+-montmorillonite. Pyridine desorbed from Lewis sites at 150°C and from Bronsted sites at 340°C. 4-methylpyridine desorbed from Lewis and Bronsted centres at 210°C and 410°C respectively, some 60°C higher than pyridine due to its higher basicity. Conversely, the 2-methyl- and 2,6-dimethylpyridine, which are sterically hampered with respect to their coordination to Lewis centres, desorbed from these sites near 100°C, but due to their greater basicity desorbed from Bronsted sites at higher temperatures. These interpretations were confirmed by IR spectroscopy.
Preparation and characterization of iron oxide pillared montmorillonite
Authors: Doff D. H. , Gangas N. H. J. , Allan J. E. M. , Coey J. M. D.
Published: November 2006

Pillared smectites in which the pillars consist of iron oxide are expected to have interesting and unusual magnetic properties. Several possible routes by which such materials might be made have been investigated, namely intercalation of hydroxy-Fe(III) polycations, mixed hydroxy-Fe(III)/Al polycations, phenanthroline-Fe(II) cations, and trinuclear Fe(III) acetato cations into Na-montmorillonite. Only the last of these yielded a pillared clay (PILC) on calcination. The products have been characterized using X-ray powder diffraction and 57Fe Mössbauer spectroscopy. The precursor Fe-PILC has a d-spacing of 21 Å and expands to 23 Å on solvation with glycol. The calcined Fe-PILC has a d-spacing of 19 Å (gallery height 9·4 Å) and does not expand with glycol, confirming cross-linking of the layers. From Mössbauer spectra at 4·2 K it is estimated that there are of the order of some hundred Fe atoms per pillar.
The relation between the terra rossa and the carbonate-free residue of the underlying limestones and dolostones in Apulia, Italy
Authors: Moresi M. , Mongelli G.
Published: November 2006

A statistical comparison has been made of chemical data for terra rossa and carbonate-free residues of Cretaceous limestones and dolostones in Apulia in order to evaluate the hypothesis that the terra rossa is a product of weathering of the underlying carbonate rocks. It has been shown that the differences in chemical composition between the residue of the carbonate rocks and the terra rossa are consistent with the former being the parent material of the latter. The transformation from carbonate rock residue to terra rossa was governed mainly by chemical weathering which produced a marked decrease in the K2O/Al2O3 (i.e. illite/kaolinite) ratio. The geochemical pattern of the Apulian terra rossa has been influenced by sedimentary processes which have led to a characteristic distribution of mineralogical components and a moderate contamination by biogenic silica.
Clay stability in clay-dominated soil systems
Authors: Righi D. , Velde B. , Meunier A.
Published: November 2006

Seven samples from a chronosequence of soils developed in historically created polders on the Atlantic coast (Marais Poitevin, Vendée, France) were investigated in order to illustrate the rate of mineralogical change in a clay-dominated system. The oldest polder was constructed in 1665, the last one in 1912; thus the time span of soil evolution is from 80 to 330 years. All the samples had more than 50% clay (<2 μm). The most reactive, fine clay sub-fraction (<0.1 μm) was investigated in detail by X-ray diffraction and chemical analysis. The observed mineralogical changes with increasing age followed the schematic reaction:

smectite + mica = illite + mixed-layer minerals.

The progress of reaction in time appears to be non-linear. This reaction seems to occur in a chemically constant system, and the mineralogical change can be seen as a readjustment of species to a given chemical composition.
Acid dissolution of synthetic aluminous goethite before and after transformation to hematite by heating
Authors: Ruan H. D. , Gilkes R. J.
Published: November 2006

Measurements of the kinetics of acid dissolution of synthetic aluminous goethites and corresponding hematites produced by heating of parent Al-goethites at various temperatures were carried out in 1 M HC1 at 30, 40 and 50°C. Dissolution-time curves show sigmoidal shapes for the goethites (110°C), whereas deceleratory shapes were obtained for most of the partly and fully dehydroxylated samples. The dissolution rate for all materials decreased with increasing Al substitution and increased with increasing dissolution temperature, specific surface area and heating temperature. On a unit surface area basis, hematite dissolved ∼ 2–8 times faster than goethite. Dissolution kinetics of most heated goethite samples (200–260°C) were quite well described (R2 > 0.96) by the modified first-order Kabai equation. The activation energy and frequency factor for dissolution increased with increasing Al substitution.
Clay mineral variations associated with diagenesis and low-grade metamorphism of Early Cretaceous sediments in the Cameros Basin, Spain
Authors: Barrenechea J. F. , Rodas M. , Mas J. R.
Published: November 2006

The clay mineral distribution in the Early Cretaceous depositional sequences along the Cameros Basin has been established on the basis of XRD traces and TEM/EDAX analyses. Samples from the Latest Berriasian-Barremian depositional sequences are characteristic of epimetamorphic conditions. Illite ‘crystallinities’ are broader than expected (0.35–0.490°Δ2θ), due to the consistent presence of K-mica-paragonite mixed-layer and discrete paragonite associated with the illite 10 Å peak. The Late Barremian-Early Aptian depositional sequence, around the depocentral sector of the basin, represents a sudden change to anchimetamorphic conditions, marked by the presence of pyrophyllite and rectorite and by a significant decrease in the A1IVcontent of the chlorites. Towards the northwestern border of the basin, this sequence was affected by deep diagenetic conditions, as deduced from the clay mineral association and the ‘crystallinity’ values (0.57°Δ2θ). The changes in the clay mineral assemblages and ‘crystallinity’ data can hardly be explained in terms of the varying burial depth and are related to changes in the circulation of fluids associated with varying facies (modal composition, grain size). Permeability is regarded as the main factor controlling the circulation of these migratory fluids.
Detailed study of smectite genesis in granitic saprolites by analytical electron microsopy
Authors: Aoudjit H. , Robert M. , Elsass F. , Curmi P.
Published: November 2006

: Smectite genesis in two granitic saprolites was studied, using qualitative and quantitative mineralogical methods and high resolution transmission electron microscopy (HRTEM). The primary minerals (plagioclase and mica) give rise to the formation of different kinds of smectites according to the weathering conditions (pH and drainage). Under a relatively basic, drained environment, a neoformed montmorillonite with a spheroidal organization exists in fillings of plagioclase cores. In the same conditions biotites are transformed into beidellites with a quasi-crystal organization. Under hydromorphic conditions, muscovites evolve incompletely towards smectites, whereas biotites lead to a montmorillonite with a tactoid organization.
ESCA and solid-state NMR studies of allophane
Authors: He N. , Barr T. L. , Klinowski J.
Published: November 2006

The surface/near-surface chemistry of allophane has been studied by X-ray photoelectron spectroscopy (ESCA) and the bulk material by 27A1 and 29Si solid-state NMR and other techniques. The surface/near-surface Si/Al ratio of allophane is c.1.0, similar to that for kaolinite, zeolite Na-A and sodalite. The core level binding energies for kaolinite and allophane are almost identical, but quite different from those for zeolite Na-A and sodalite, both framework aluminosilicates. The nature and size of these differences is consistent with the differences between the chemistry of sheet and framework silicates. The small variations in the Si(2p) spectra for kaolinite and allophane are discussed in terms of bonding of the tetrahedral units in the two materials.
REE distribution in presentday and ancient surface environments of basaltic rocks (Central Portugal)
Authors: Prudêncio M. I. , Gouveia M. A. , Sequeira Braga M. A.
Published: November 2006

Rare earth elements are mobilized, fractionated and precipitated during weathering processes of basaltic rocks of the Lisbon Volcanic Complex. In general there is an increase in the REE contents in the whole samples with increasing weathering and fractionation between LREE and HREE. Cerium is partially oxidized and Ce4+ is retained resulting in negative Ce anomalies in the whole samples of the base and middle profile zones. In the clay fraction there is an increase in the REE contents from the top to the bottom of the profiles, except for Ce, giving rise to positive Ce anomalies in the top and negative anomalies of this element in the middle and bottom of the profiles. Significant positive Ce anomalies occur in the finer fractions of palaeoweathered (Upper Cretaceous/ Lower Eocene) basalts associated with low REE contents relative to the whole samples indicating more intense leaching conditions in the Upper Cretaceous/Lower Eocene than at the present day. However, in both cases no positive Ce anomalies were found in the whole samples. There appears to be a negative correlation between the (La/Yb)ch ratio variation and the clay mineralogy/drainage conditions.
The 1640 cm-1 infrared band, monitor for the gain and thermal stability of water produced in ground kaolinites
Authors: Mendelovici E. , Villalba R. , Sagarzazu A. , Carias O.
Published: November 2006

The development of the infrared (IR) absorption band at 1640 cm−1 (δH2O) is employed to monitor the gain in molecular water of progressively mortar-ground kaolinite. The planimetred area of this band shows a linear correlation with weight loss at 105°C (free moisture) between 2 and 18 h grinding, indicating a steady increase of molecular water in this range. Heating of ground products to 105°C causes a decrease of about ⅓ in the 1640 cm−1 peak area for all ground samples. This area decrease corresponds to a 34% (average) loss of free moisture as determined by gravimetry. The remaining water is held up to 280°C and is more tightly held in the kaolinite ground for shorter (2–5 h) intervals than in further ground kaolinites. The 1640 cm−1 peak is not detected in any ground kaolinite after heating to 600°C the temperature at which kaolinite dehydroxylates completely. The differentiation of the energetically different OH groups present in ground kaolinite and the mechanism of water gain are compared and discussed from IR spectroscopy and weight loss results.
Etude comparee des complexes hectorite- et vermiculite-decylammonium a l'aide des spectrometries infrarouge et raman
Authors: Vimond-Laboudigue A. , Prost R.
Published: November 2006

Resume

L'arrangement des cations décylammonium échangés entre les feuillets de la vermiculite et de l'hectorite a été précisé à l'aide des spectrométries infrarouge (IR) et Raman. Les expériences de deutération et de dichroïsme faites par spectrométrie IR montrent que l'axe C3 du groupe NH3+ est confondu avec l'axe de la cavité hexagonale sous-jacente, dans le cas de la vermiculite comme dans celui de l'hectorite, et que dans la vermiculite, les groupes NH sont engagés dans des liaisons hydrogène avec les atomes d'oxygène des tétraèdres substitués. La spectrométrie Raman permet de comparer l'arrangement des chaînes alkyles dans les deux phyllosilicates. En effet, cette technique donne accès à des modes de vibration très sensibles à la conformation des chaînes carbonées, en particulier grâce à la décomposition des bandes de vibration de valence des groupements CH2 et CH3. Ainsi, dans la vermiculite, on montre que les chaînes sont linéaires, et que leur arrangement interdigité est proche de celui du chlorure de décylammonium cristallisé. Les spectres Raman obtenus pour l'hectorite mettent en évidence l'existence de conformations gauches dans les chaînes alkyles, qui caractérisent une rotation de la chaîne autour de la liaison C-C voisine du groupe NH3+ terminal. Les résultats obtenus en Raman montrent par ailleurs que les interactions entre les chaînes alkyles sont beaucoup plus faibles que dans le cas de la vermiculite et confortent le modèle proposé ici pour le complexe hectorite-décylammonium, pour lequel les chaînes sont parallèle aux surfaces des feuillets.
Clay mineral evolution in the Illinois Basin and its causes
Authors: Gharrabi M. , Velde B.
Published: November 2006

Samples from deep wells of the Palaeozoic Illinois Basin show the evolution of the illite-smectite (I-S) mineral transformation under low temperatures for very long periods of time. Curve decomposition of the XRD traces was used to identify and follow the evolution of the different clay minerals. All samples showed the presence of a large amount of illite (fine and coarse grained micaceous material) and a much smaller quantity of I-S. In a vertical section the R=1, I-S diffraction peak initially changes with depth indicating change from 80 to 95% illite content but it changes little with further depth. The I-S intensity decreases with depth compared with the illite peaks. These relations indicate that the clays in the Palaeozoic sequence of the Illinois Basin evolve continuously in the deep well, It appears that the final stages of I-S mineral transformation can reach a compositional stagnation (smectite content) as the I-S phase is dissolved to produce illite.

Using a kinetic model to describe the smectite to illite clay transformation, it is deduced that the Illinois basin had a longer period of deposition than indicated by present stratigraphy and that almost 1.5 km of sediments deposited in the Mesozoic were eroded in later Tertiary times. These conclusions are confirmed by published data on the maturation of organic matter.
Mineralogy and geochemistry of Devonian detrital rocks from the Iberian Range (Spain)
Authors: Bauluz Lazaro B. , Mayayo Burillo M.J. , Fernandez-Nieto C. , Gonzalez Lopez J.M.
Published: November 2006

Two profiles in Devonian marine deposits have been studied, consisting of pelites, subgreywackes, greywackes and quartzites. Quartz and clay minerals are major components and feldspar and calcite are minor ones. Phyllosilicates in the fine fractions are kaolinite and illite; kaolinite has a high degree of ordering; illite is predominantly of a 1Md polytype, with low Na content and poor crystallinity and has a phengitic composition in greywackes, whereas in pelites it is muscovitic in composition. Both phyllosilicates may be inherited from a source area with intensive weathering processes, although illite may also be a diagenetic phase. These mineral characteristics indicate that the Devonian rocks did not reach the anchizone boundary in their post-depositional evolution.

The chemical composition of pelites and subgreywackes reveals a high degree of chemical maturity. Chondrite-normalized REE patterns indicate a higher degree of weathering of these Devonian sediments than of Post-Archaean Australian Shales (PAAS), possibly as a consequence of sedimentary recycling processes. The REE patterns of the Devonian rocks in addition to the high Th/Sc, La/Sc and Th/Co ratios suggest a felsic composition of the primitive source area, probably a K-rich granite.
Comparative study of the transition between very low-grade and low-grade metamorphism in siliciclastic and carbonate sediments: Early Cretaceous, Cameros Basin (northern Spain)
Authors: Alonso-Azcarate J. , Barrenechea J. F. , Rodas M. , Mas J. R.
Published: November 2006

The transition between very low-grade and low-grade metamorphism has been studied in the Urbión and Enciso Groups of the Late Jurassic-Early Cretaceous Cameros basin (NE Spain). The ‘illite crystallinity’ (IC) values do not appear to be controlled by burial depth but rather by: (1) XRD overlap with other phases (e.g. paragonite and mixed-layered muscovite-paragonite) in the siliciclastic samples; (2) the presence of carbonates, which delay illitization, resulting in an increase in the IC values, that becomes more pronounced as the P-T conditions decrease towards the diagenesis zone; and (3) the permeability of the sediments, which controls the circulation of metamorphic fluids and therefore the distribution of ‘crystallinities’ and mineral assemblages within the basin.

The anchizone is represented by a narrow range of ‘chlorite crystallinity’ (ChC) values. Therefore, ChC is a less sensitive parameter than IC for estimating changes from diagenetic to low-grade metamorphic conditions. However, ChC can be a useful tool when there is a great heterogeneity of facies types, as it is not affected by the presence of carbonates.
Systematic assignment of thermodynamic constraints in metabolic network models
Authors: Kümmel Anne , Panke Sven , Heinemann Matthias
Published: November 2006

Background

The availability of genome sequences for many organisms enabled the reconstruction of several genome-scale metabolic network models. Currently, significant efforts are put into the automated reconstruction of such models. For this, several computational tools have been developed that particularly assist in identifying and compiling the organism-specific lists of metabolic reactions. In contrast, the last step of the model reconstruction process, which is the definition of the thermodynamic constraints in terms of reaction directionalities, still needs to be done manually. No computational method exists that allows for an automated and systematic assignment of reaction directions in genome-scale models.

Results

We present an algorithm that – based on thermodynamics, network topology and heuristic rules – automatically assigns reaction directions in metabolic models such that the reaction network is thermodynamically feasible with respect to the production of energy equivalents. It first exploits all available experimentally derived Gibbs energies of formation to identify irreversible reactions. As these thermodynamic data are not available for all metabolites, in a next step, further reaction directions are assigned on the basis of network topology considerations and thermodynamics-based heuristic rules. Briefly, the algorithm identifies reaction subsets from the metabolic network that are able to convert low-energy co-substrates into their high-energy counterparts and thus net produce energy. Our algorithm aims at disabling such thermodynamically infeasible cyclic operation of reaction subnetworks by assigning reaction directions based on a set of thermodynamics-derived heuristic rules. We demonstrate our algorithm on a genome-scale metabolic model of E. coli. The introduced systematic direction assignment yielded 130 irreversible reactions (out of 920 total reactions), which corresponds to about 70% of all irreversible reactions that are required to disable thermodynamically infeasible energy production.

Conclusion

Although not being fully comprehensive, our algorithm for systematic reaction direction assignment could define a significant number of irreversible reactions automatically with low computational effort. We envision that the presented algorithm is a valuable part of a computational framework that assists the automated reconstruction of genome-scale metabolic models.
Comparison of human uterine cervical electrical impedance measurements derived using two tetrapolar probes of different sizes
Authors: Gandhi Saurabh V , Walker Dawn C , Brown Brian H , Anumba Dilly OC
Published: November 2006

Background

We sought to compare uterine cervical electrical impedance spectroscopy measurements employing two probes of different sizes, and to employ a finite element model to predict and compare the fraction of electrical current derived from subepithelial stromal tissue.

Methods

Cervical impedance was measured in 12 subjects during early pregnancy using 2 different sizes of the probes on each subject.

Results

Mean cervical resistivity was significantly higher (5.4 vs. 2.8 Ωm; p < 0.001) with the smaller probe in the frequency rage of 4–819 kHz. There was no difference in the short-term intra-observer variability between the two probes. The cervical impedance measurements derived in vivo followed the pattern predicted by the finite element model.

Conclusion

Inter-electrode distance on the probes for measuring cervical impedance influences the tissue resistivity values obtained. Determining the appropriate probe size is necessary when conducting clinical studies of resistivity of the cervix and other human tissues.
A study of association between common variation in the growth hormone-chorionic somatomammotropin hormone gene cluster and adult fasting insulin in a UK Caucasian population
Authors: Freathy Rachel M , Mitchell Simon MS , Knight Beatrice , Shields Beverley , Weedon Michael N , Hattersley Andrew T , Frayling Timothy M
Published: November 2006

Background

Reduced growth during infancy is associated with adult insulin resistance. In a UK Caucasian cohort, the CSH1.01 microsatellite polymorphism in the growth hormone-chorionic somatomammotropin hormone gene cluster was recently associated with increases in adult fasting insulin of approximately 23 pmol/l for TT homozygote males compared to D1D1 or D2D2 homozygotes (P = 0.001 and 0.009; n = 206 and 92, respectively), but not for females. TT males additionally had a 547-g lower weight at 1 year (n = 270; P = 0.008) than D2D2 males. We sought to replicate these data in healthy UK Caucasian subjects. We genotyped 1396 subjects (fathers, mothers and children) from a consecutive birth study for the CSH1.01 marker and analysed genotypes for association with 1-year weight in boys and fasting insulin in fathers.

Results

We found no evidence for association of CSH1.01 genotype with adult male fasting insulin concentrations (TT/D1D1 P = 0.38; TT/D2D2 P = 0.18) or weight at 1 year in boys (TT/D1D1 P = 0.76; TT/D2D2 P = 0.85). For fasting insulin, our data can exclude the previously observed effect sizes as the 95 % confidence intervals for the differences observed in our study exclude increases in fasting insulin of 9.0 and 12.6 pmol/l for TT relative to D1D1 and D2D2 homozygotes, respectively. Whilst we have fewer data on boys' 1-year weight than the original study, our data can exclude a reduction in 1-year weight greater than 557 g for TT relative to D2D2 homozygotes.

Conclusion

We have not found association of the CSH1.01 genotype with fasting insulin or weight at 1 year. We conclude that the original study is likely to have over-estimated the effect size for fasting insulin, or that the difference in results reflects the younger age of subjects in this study relative to those in the previous study.
Giant solitary fibrous tumour of the liver
Authors: Terkivatan Türkan , Kliffen Mike , de Wilt Johannes HW , van Geel Albertus N , Eggermont Alexander MM , Verhoef Cornelis
Published: November 2006

Background

Solitary fibrous tumour (SFT) is an uncommon mesenchymal neoplasm that most frequently affects the pleura, although it has been reported with increasing frequency in various other sites such as in the peritoneum, pericardium and in non-serosal sites such as lung parenchyma, upper respiratory tract, orbit, thyroid, parotid gland, or thymus. Liver parenchyma is rarely affected. Clinically, SFTs cause symptoms after having reached a certain size or when vital structures are involved. In recent years, SFTs are more often identified and distinguished from other tumours with a similar appearance due to the availability of characteristic immunohistochemical markers.

Case presentation

In this manuscript we report the case of a large tumour of the liver, which was histologically diagnosed as a SFT, and showed involvement of a single hepatic segment. Because of the patient's presentation and clinical course, it may represent a radiation-induced lesion.

Conclusion

When a SFT has been diagnosed, surgery is the treatment of choice. The small number of patients with a SFT of the liver and its unknown natural behaviour creates the need to a careful registration and follow-up of all identified cases