bluuebunny/crossref_metadata_2025 huggingface dataset:
Regulation of Type III Iodothyronine Deiodinase Expression in Human Cell Lines
Authors: Kester Monique H. A. , Kuiper George G. J. M. , Versteeg Rogier , Visser Theo J.
Published: August 2006

Type I iodothyronine deiodinase (D1) and type II iodothyronine deiodinase (D2) catalyze the activation of the prohormone T4 to the active hormone T3; type III iodothyronine deiodinase (D3) catalyzes the inactivation of T4 and T3. D3 is highly expressed in brain, placenta, pregnant uterus, and fetal tissues and plays an important role in regulating thyroid hormone bioavailability during fetal development. We examined the activity of the different deiodinases in human cell lines and investigated the regulation of D3 activity and mRNA expression in these cell lines, as well as its possible coexpression with neighboring genes Dlk1 and Dio3os, which may also be especially important during development. D1 activity and mRNA were only found in HepG2 hepatocarcinoma cells, and D2 activity was observed in none of the cell lines. D3 activity and mRNA was found in ECC-1 endometrium carcinoma cells, MCF-7 mammacarcinoma cells, WRL-68 embryonic liver cells, and SH-SY5Y neuroblastoma cells, but not in the HepG2 hepatocarcinoma cell line or in any choriocarcinoma or astrocytoma cell line. We demonstrated that the phorbol ester 12-O-tetradecanoylphorbol-13-acetate increased D3 activity 2- to 9-fold in ECC-1, MCF-7, WRL-68, and SH-SY5Y cells. Estradiol increased D3 activity 3-fold in ECC-1, but not in any other cells. Dexamethasone decreased D3 activity in WRL-68 cells only in the absence of fetal calf serum. Incubation with retinoids increased D3 activity 2- to 3-fold in ECC-1, WRL-68, and MCF-7 cells but decreased D3 activity in SH-SY5Y cells. D3 expression in the different cells was not affected by cAMP or thyroid hormone. Interestingly, D3 mRNA expression in the different cell lines strongly correlated with Dio3os mRNA expression and in a large set of neuroblastoma cell lines also with Dlk1 expression. In conclusion, we identified different human D3-expressing cell lines, in which the regulation of D3 expression is cell type-specific. Our data suggest that estradiol may be one of the factors contributing to the induction of D3 activity in the pregnant uterus and that in addition to gene-specific regulatory elements, more distant common regulatory elements also may be involved in the regulation of D3 expression.
Caveolin-1 Regulates Cellular Trafficking and Function of the Glucagon-Like Peptide 1 Receptor
Authors: Syme Colin A. , Zhang Lei , Bisello Alessandro
Published: August 2006

The glucagon-like peptide 1 receptor (GLP-1R) mediates important effects on β-cell function and glucose homeostasis and is one of the most promising therapeutic targets for type 2, and possibly type 1, diabetes. Yet, little is known regarding the molecular and cellular mechanisms that regulate its function. Therefore, we examined the cellular trafficking of the GLP-1R and the relation between receptor localization and signaling activity. In resting human embryonic kidney 293 and insulinoma MIN6 cells, a fully functional green fluorescent protein-tagged GLP-1R was localized both at the cell membrane and in highly mobile intracellular compartments. Real-time confocal fluorescence microscopy allowed direct visualization of constitutive cycling of the receptor. Overexpression of K44A-dynamin increased the number of functional receptors at the cell membrane. Immunoprecipitation, sucrose sedimentation, and microscopy observations demonstrated that the GLP-1R localizes in lipid rafts and interacts with caveolin-1. This interaction is necessary for membrane localization of the GLP-1R, because overexpression of a dominant-negative form of caveolin-1 (P132L-cav1) or specific mutations within the putative GLP-1R’s caveolin-1 binding domain completely inhibited GLP-1 binding and activity. Upon agonist stimulation, the GLP-1R underwent rapid and extensive endocytosis independently from arrestins but in association with caveolin-1. Finally, GLP-1R-stimulated activation of ERK1/2, which involves transactivation of epidermal growth factor receptors, required lipid raft integrity. In summary, the interaction of the GLP-1R with caveolin-1 regulates subcellular localization, trafficking, and signaling activity. This study provides further evidence of the key role of accessory proteins in specifying the cellular behavior of G protein-coupled receptors.
Spectacular Sex: Thought and Pleasure in the Encounter with Pornography
Authors: Lubey Kathleen
Published: August 2006

kathleen lubey is Assistant Professor of English at St. John's University in Queens, New York. She is currently completing a book that considers sexuality and aesthetics as interrelated sites of literary experimentation in eighteenth-century Britain. An excerpt from this project, “Eliza Haywood's Amatory Aesthetic,” appears in Eighteenth-Century Studies 39.3 (Spring 2006).
Some Notes on Women and Abstraction and a Curious Case History: Alice Neel as a Great Abstract Painter
Authors: Schor Mira
Published: August 2006

mira schor is a painter and writer. She is the author of Wet: On Painting, Feminism, and Art Culture (Duke University Press, 1997) and coeditor of M/E/A/N/I/N/G: An Anthology of Artists' Writings, Theory, and Criticism (Duke University Press, 2000). She teaches in the mfa Program of the Fine Arts Department at Parsons The New School for Design. She also teaches at SVA in the mfa in Art Criticism Program and in the MassArt Low Residency mfa Program at fawc in Provincetown, Massachussetts. She is currently completing work on a new collection of her essays and is editing The Extreme of the Middle, the collected writings of the Abstract Expressionist painter Jack Tworkov.
The dwarf phenotype of theArabidopsis acl5mutant is suppressed by a mutation in an upstream ORF of a bHLH gene
Authors: Imai Akihiro , Hanzawa Yoshie , Komura Mio , Yamamoto Kotaro T. , Komeda Yoshibumi , Takahashi Taku
Published: August 2006

Loss-of-function mutants of the Arabidopsis thaliana ACAULIS 5(ACL5) gene, which encodes spermine synthase, exhibit a severe dwarf phenotype. To elucidate the ACL5-mediated regulatory pathways of stem internode elongation, we isolated four suppressor of acaulis(sac) mutants that reverse the acl5 dwarf phenotype. Because these mutants do not rescue the dwarfism of known phytohormone-related mutants, the SAC genes appear to act specifically on the ACL5 pathways. We identify the gene responsible for the dominant sac51-d mutant, which almost completely suppresses the acl5phenotype. sac51-d disrupts a short upstream open reading frame(uORF) of SAC51, which encodes a bHLH-type transcription factor. Our results indicate that premature termination of the uORF in sac51-dresults in an increase in its own transcript level, probably as a result of an increased translation of the main ORF. We suggest a model in which ACL5 plays a role in the translational activation of SAC51,which may lead to the expression of a subset of genes required for stem elongation.
Crystal structure of the UPF2-interacting domain of nonsense-mediated mRNA decay factor UPF1
Authors: Kadlec Jan , Guilligay Delphine , Ravelli Raimond B. , Cusack Stephen
Published: August 2006

UPF1 is an essential eukaryotic RNA helicase that plays a key role in various mRNA degradation pathways, notably nonsense-mediated mRNA decay (NMD). In combination with UPF2 and UPF3, it forms part of the surveillance complex that detects mRNAs containing premature stop codons and triggers their degradation in all organisms studied from yeast to human. We describe the 3 Å resolution crystal structure of the highly conserved cysteine–histidine-rich domain of human UPF1 and show that it is a unique combination of three zinc-binding motifs arranged into two tandem modules related to the RING-box and U-box domains of ubiquitin ligases. This UPF1 domain interacts with UPF2, and we identified by mutational analysis residues in two distinct conserved surface regions of UPF1 that mediate this interaction. UPF1 residues we identify as important for the interaction with UPF2 are not conserved in UPF1 homologs from certain unicellular parasites that also appear to lack UPF2 in their genomes.
Genome-wide analysis of mRNAs bound to the histone stem–loop binding protein
Authors: Townley-Tilson W.H. Davin , Pendergrass Sarah A. , Marzluff William F. , Whitfield Michael L.
Published: August 2006

The replication-dependent histone mRNAs are cell-cycle-regulated and expressed only during S phase. In contrast to all other eukaryotic mRNAs, the histone mRNAs end in a highly conserved 16-nucleotide stem–loop rather than a poly(A) tail. The stem–loop is necessary and sufficient for the post-transcriptional regulation of histone mRNA during the cell cycle. The histone mRNA 3′ stem–loop is bound by the stem–loop binding protein (SLBP) that is involved in pre-mRNA processing, translation, and stability of histone mRNA. Immunoprecipitation (IP) of RNA-binding proteins (RBPs) followed by microarray analysis has been used to identify the targets of RNA-binding proteins. This method is sometimes referred to as RIP-Chip (RNA IP followed by microarray analysis). Here we introduce a variation on the RIP-Chip method that uses a recombinant RBP to identify mRNA targets in a pool of total RNA; we call this method recombinant, or rRIP-Chip. Using this method, we show that recombinant SLBP binds exclusively to all five classes of histone mRNA. We also analyze the messages bound to the endogenous SLBP on polyribosomes by immunoprecipitation. We use two different microarray platforms to identify enriched mRNAs. Both platforms demonstrate remarkable specificity and consistency of results. Our data suggest that the replication-dependent histone mRNAs are likely to be the sole target of SLBP.
Synthesis of Hydrotalcite-Like Compounds and their Physico-Chemical Properties—The Systems Mg2+-Al3+-SO42− and Mg2+-Al3+-CrO42−
Authors: Miyata Shigeo , Okada Akira
Published: August 2006

Hydrotalcite-like compounds [MgI − xAlx(OH)2]x+ [A2−x/2, mH2O]x−, where A2− is SO42− or CrO42− and x ≇ 0.25, were prepared by a coprecipitation method and their physico-chemical properties were studied by X-ray diffraction, thermal analysis, i.r. absorption spectra and acidity-basicity measurement.

The compounds including SO42− and CrO42− were analogous to an orthorhombic hydrotalcite and the lattice constants, a0 and c0 were 3.05 and 25.97 Å, and 3.05 and 26.48 Å, respectively. The crystallite size and strain in the 003 direction were 127 Å and 4.77 × 10−2 for the SO42− system or 83 Å and 6.60 × 10−2 for the CrO42− system, indicating a largely distorted microcrystallite. Two endothermic peaks observed at 240 and 455°C for the SO42− system and at 230 and 460°C for the CrO42− system are ascribed to the eliminations of interlayer water (mH2O) and structural water, respectively. The compound including SO42− formed MgO by calcination at 500°C and MgSO4 and MgAl2O4 by calcination at 800°C while the compound including CrO42− formed MgO at 400°C and MgAl2 − xCrxO4 at 800° I.r. study of the SO42− compound indicated that the bonding of SO42− was a bridge type. The highest acid and base strengths of the SO42− compound were H0 ≤ 1.5 and H− ≥ 12.2, the acidity and basicity being 0.3 and 0.1 mmol/g, respectively.
Crystal Nucleation and Growth in Hydrolysing Iron(III) Chloride Solutions
Authors: Atkinson R. J. , Posner A. M. , Quirk J. P.
Published: August 2006

0.5 molal iron(III) chloride solutions were hydrolysed at room temperature by base additions in the range OH/Fe mole ratio 0–2.75. After an ageing period the hydrolysed solutions were used to produce amorphous hydroxide gels from which crystalline products were grown at 65°C, at low pH or high pH. Examination of crystal composition and morphology and comparison with similarly treated nitrate solutions showed that the nucleation of hematite and goethite is inhibited in chloride containing solutions, which allow growth of small rod shaped β-FeOOH to predominate or occur exclusively in gels at pH 1–2. The addition of seed crystals of hematite and goethite allows competitive growth of all three minerals. The transformations β-FeOOH → α-Fe2O3 and β-FeOOH → α-FeOOH at pH 1–2 proceed by dissolution and reprecipitation and are promoted by adding seed crystals.
A Comparative Study of Thermal Effects on Surface and Structural Parameters of Natural Californian and Quebec Chrysotile Asbestos up to 700°C
Authors: Murphy William J. , Ross Robert A.
Published: August 2006

The effect of heat treatment on surface area, pore volume, pore size distribution, physical and chemical structure up to 700°C have been studied on samples of naturally occurring chrysotile minerals from California and Quebec. Techniques used included thermogravimetric analysis, low-temperature nitrogen adsorption, electron microscopy, X-ray powder and electron diffraction. The materials behaved similarly on heating to 100°C showing a 0.5% weight loss attributable to desorption of physisorbed water. At 500°C, Quebec samples retained the chrysotile crystal structure while Californian samples were X-ray amorphous. Forsterite was formed by dehydration of both chrysotiles at 700°C; the greater stability of the Quebec samples to this process is explained by the presence of brucite as an impurity which enters into stray solid-solid interactions with the chrysotile.
Gas Chromatographic Pathways for Certain Chloro-Alkylammonium Montmorillonites
Authors: McAtee James L. , Harris Brent R.
Published: August 2006

A series of chloro-alkylammonium montmorillonites was produced by cation exchange from Na+-montmorillonite. Gas chromatographic data were obtained for light hydrocarbons and certain oxides of nitrogen. Surface area and X-ray powder diffraction studies were made on each organo-clay, making possible differentiation between possible chromatographic pathways. Adsorption of the gas molecules on the silicate sheet was determined to be the dominant chromatographic pathway for all gases studied.
X-Ray Study of the Interlayer Region of a Barium-Vermiculite
Authors: Telleria M. I. , Slade P. G. , Radoslovich E. W.
Published: August 2006

An X-ray diffraction analysis of a barium-vermiculite shows it to have a triclinic unit cell with the following dimensions a = 5.33, b = 9.26, c = 12.47 Å, α = 100.75°, ß = 93.5° and γ = 90°. The proposed structure, adjusted in space group Cl, has the exchangeable cations approximately over the ditrigonal holes of the silicate surface and on either side of a hexagonal network of water molecules extending over the middle of the interlamellar region. The interlayer material imposes a relative displacement of ± b/4 on adjacent silicate sheets. The importance of these displacements, not previously found in layer silicates, is emphasized.
Azobenzene Intercalates of Montmorillonite
Authors: Adams J. M. , Reid P. I.
Published: August 2006

A study has been made of the interaction of azobenzene vapor with a series of cation-exchanged montmorillonites. Cu2+- and Ag+-clays give basal spacings ≥ 20Å. The azobenzene retains its trans conformation in the clay and can be extracted with ether. If the intercalate is heated above 120°C then there is catalytic decomposition leaving a black product. Infrared spectra of an extract from this product suggests that it might be made up of a mixture of amines. A photo-electron spectroscopic study shows that the nitrogen is in two distinct chemical environments both in the initial and in the blackened intercalates. The C:N ratio remains at 6:1 throughout.
Synthesis and Swelling Properties of Saponites with Increasing Layer Charge
Authors: Suquet H. , Iiyama J. T. , Kodama H. , Pezerat H.
Published: August 2006

Nine synthetic Na-saponites with charge densities varying between 0.33 and 1.0 have been prepared. Their swelling properties and structural organization in water, ethylene glycol and glycerol show discontinuities in the physico-chemical behaviour of these samples. The layer charge densities caused changes in swelling properties and structural organization of the minerals. These changes also depended upon the nature of the solvation liquid and the interlayer cation involved.

Electron diffraction patterns of the Ba-saponites showed no abnormal diffusion making honeycomblike patterns between Bragg reflections.

The results indicate criteria for estimating the layer charge of tetrahedrally substituted trioctahedral 2/1 phyllosilicates.

There is no upper limit until x = 1 for the layer charge x which is specific to the smectite-group. Consequently, the changes in the swelling properties observed when x = 0.5-0.6 and x = 0.8-0.9 come from the modifications of the interlayer structure, which are mainly a function of cation-liquid and silicate layer-liquid interactions. Consequently, there is an overlap between the saponite and the vermi-culite mineral groups.
Properties and Quantitative Estimation of Poorly Crystalline Components in Sesquioxidic Soil Clays
Authors: Fey M. V. , Le Roux J.
Published: August 2006

Sesquioxidic soil clays from Oxisols in South Africa, Australia and Brazil, and two clays from Andosols in Japan and New Zealand, were investigated by selective dissolution techniques. Acid ammonium oxalate (pH 3) was found to be superior to currently popular alkaline reagents for extracting amorphous aluminosilicates and alumina from these clays. Boiling 0.5 N NaOH dissolved large amounts of finely-divided kaolinite and halloysite, while hot 5% Na2CO3 reaction was too slow (partial dissolution of synthetic amorphous aluminosilicates with one extraction) and insufficiently selective (gibbsite and kaolin of poor crystallinity dissolve to a variable extent). On the other hand, synthetic gels (molar SiO2/Al2O3 ranging from 0.91 to 2.55) dissolved completely after 2 hr shaking in the dark with 0.2 M acid ammonium oxalate (0.2 ml/mg). Specificity of oxalate for natural allophane was indicated by removal of similar quantities of silica and alumina using different clay:solution ratios. Oxalate extraction data indicated that allophane is absent in Oxisol clays. Allophane was determined quantitatively in volcanic-ash soil clays by allocating hydroxyl water content to oxalate-soluble silica plus alumina on the basis of an ignition weight loss-chemical composition function for synthetic amorphous alumino-silicates. Parameters of chemical reactivity and distribution of electric charges following various chemical pretreatments of allophane were found to correspond closely to those predicted on the basis of synthetic gel behaviour. Results for Oxisol clays suggested that the role of amorphous (oxalate-soluble) alumina in governing physicochemical properties is generally less than that of the poorly-crystalline, Al-substituted iron oxide component which is removed by deferration with citrate-dithionite-bicarbonate reagent.
On the Evaluation of Nutrient Pools of Forest Soils
Authors: Thompson Graham R. , Behan Mark , Mandzak John , Bowen Chris
Published: August 2006

The standard method of assessing the available portion of the nutrient reservoir of a forest soil is to use a neutral salt solution, such as NH4OAc, to extract the exchangeable plus dissolved ions, which are analyzed and considered available. This approach, designed for evaluating nutrients available for the short growth term of agricultural crops, is inadequate for assessing the nutrient pool of forests where tree growth term may reach 100 yr or more.

Soil nutrient reservoirs were evaluated in two forest soils for K, Na, Ca, Mg and Fe, using an approach based on continuous extraction of the elements and kinetic analyses of the extraction rate curves. The analyses of the curves indicate that K, Na, Ca and Fe are each released at four separate
constant rates, and Mg is released at three separate constant rates. By analogy with similar kinetic studies done on monomineralic layer silicate samples, each separate extraction rate is thought to correspond to a single type of bond site in the soil. Higher extraction rates indicate greater ease of removal and are interpreted as indicating a higher degree of availability relative to the extractant.

The available K reserves of the Everett soil evaluated by standard methods, compared with annual net K uptake rates of its forest system, indicates growth limiting K deficiency in 12–17 yr. K availability assessed by kinetic analyses indicates about 100 yr supply of K is available.
Qualitative and Quantitative Study of Stacking Faults in a Hydrazine Treated Kaolinite—Relationship with the Infrared Spectra
Authors: Barrios J. , Plançon A. , Cruz M. I. , Tchoubar C.
Published: August 2006

Artificial stacking faults can be created within a well-crystallized kaolinite by intercalating and removing hydrazine. X-ray powder patterns with electron microscopy show that the created defects are ±b/3 translations with a proportion 0.30. The infrared spectrum of the treated kaolinite is not modified with respect to the starting one. On the other hand, a natural kaolinite containing defects by displacement of Al vacancies in a similar proportion shows an infrared spectrum significantly different from that of a well-crystallized kaolinite. The modification of the infrared spectra of natural disordered kaolinites is then related to the presence of defects by change of Al vacancy positions
A Study of the Adsorption of Ni(II) and Cu(II) by Clay Minerals
Authors: Koppelman M. H. , Dillard J. G.
Published: August 2006

The adsorption of Ni(II) and Cu(II) on to the clay minerMs kaolinite, chlorite, and illite has been investigated. The quantity of Ni(II) at pH 6 and Cu(II) at pH 5 adsorbed has been found to vary in the manner chlorite > illite > kaolinite. Examination of the mode of bonding of the metal ions to the clay minerals using X-ray photoelectron spectroscopy (XPS) has been carried out. Comparison of the binding energies for metal ions in octahedral sites in selected minerals (reference minerals) and in simple nickel and copper containing compounds with values for Ni(II) and Cu(II) adsorbed on chlorite indicate that nickel(II) is probably bound as the aquo ion while copper(II) may be adsorbed as Cu(OH)+.
Selectivity and Adsorption Capacity of Smectite and Vermiculite for Aluminum of Varying Basicity
Authors: Veith J. A.
Published: August 2006

Smectite (from South Dakota, Wyoming, and Mississippi) and Vermiculite (Transvaal) were treated with solutions of Al(OH)B(3-B)+, with B varying from 0 to 2.5. The average basicity (OH/Al = B) of the Al adsorbed differed very much from the basicity of the Al added. The average basicity of the Al adsorbed by smectite was always above the average basicity of the Al added. In contrast to smectite, Vermiculite adsorbed smaller hydroxy-Al complexes. One reason for the different selective behavior was the difference in expansion between smectite (about 18 Å) and vermiculite (about 14 Å). Because of the adsorption of the relatively more basic OH-Al by smectite, smectite adsorbed considerably more Al than vermiculite. The total amount of aluminum in the interlayer generally could not be calculated by the difference between Al added and that remaining in solution after the reaction because of possible protonation of the clay mineral and adsorption of structural Al and other cations, which is more pronounced for vermiculite. The results in the present study demonstrated that neither the quantitative nor the qualitative composition of an Al(OH)B-treated exchanger can be deduced from B of the Al salts added. These points are frequently overlooked when cation exchangers are pretreated with Al of variable basicity and are used for further investigations, such as studies of CEC, surface area, interlayer spacing, anion reactions, the formation of gibbsite, etc. Before these kinds of investigations are conducted employing the pretreated OH-Al-exchangers, their composition should be known precisely.
Synthesis of Iron Layer Silicate Minerals under Natural Conditions
Authors: Harder Hermann
Published: August 2006

The low temperature synthesis of iron silicate minerals with clay structures is possible at surface temperatures only under reducing conditions. Under oxidizing conditions clay minerals could not be synthesized. Instead quartz and quartzine were found in these X-ray amorphous Fe III hydroxide-silica precipitates after 14 days at low temperatures (20° and 3°C) as well as geothite or X-ray amorphous iron hydroxides. Only from solutions containing Fe-II could the different iron-containing clay minerals be built up within days at low temperatures. The presence of Fe-II enables an octahedral layer of the brucite-gibbsite type to be formed. This is necessary for the bidimensional orientation of SiO4-tetrahedra leading to clay mineral formation. The presence of Fe2+- and/or Mg2+-ions is necessary for the formation of the Al3+- and Fe3+-containing octahedral layers. The reducing conditions were obtained in the experiments by addition of dithionite. With a high content of silica (ca. 20 ppm SiO2,7 ppm Fe) nontronite and lembergite, the di-Fe-III and tri-Fe-II octahedral, three-layer silicates, were built up in several days at low temperatures. With a lower silica content, that is, a lower Si/Fe ratio (15 ppm SiO2 and 20 ppm Fe), the two-layer silicate minerals greenalite and chamosite could be synthesized. A higher Mg content and more reducing conditions in the solutions favored the tri- as well as dioctahedral chamosite synthesis.

The conditions of formation of recent naturally formed nontronite fit well with the synthesis conditions. Chamosites in sedimentary iron ores are characterized by a low content of SiO2, between 15–30% SiO2. This low content of silica cannot be the result of primary precipitation from seawater. The iron and silica ratio in seawater or in river waters would lead to a precipitation of ~60% SiO2 in the iron hydroxide precipitates. A probable origin for chamosite iron ores, which explains the low SiO2 content, is diagenesis of the lateritic weathering crust. Indeed, investigations of recent tropical shoreline sediments and in particular their trace element content confirm that chamosite minerals have formed diagenetically from lateritic particles in reducing sediments.
Cross-Linked Smectites. II. Flocculation and Microfabric Characteristics of Hydroxy-Aluminum-Montmorillonite
Authors: Lahav N. , Shani U.
Published: August 2006

Cross-linking of Li-montmorillonite by hydroxy-aluminum oligomers was performed in a specially constructed mixing apparatus. Observations on flocculation and solution composition were carried out during and after the cross-linking reaction; the dry product was studied by scanning electron microscopy.

Flocculation was most pronounced at Al/montmorillonite ratios between 0.98 and 2.45 mM/g; below and above this range, flocculation was much less intensive. These observations can be explained by heterocoagulation and protecting colloid action. A complete neutralization of the montmorillonite charge was estimated at 1.9 mM adsorbed Al per g clay, and in order to account for the electrical charge of the hydroxy-Al, polymers with an average charge of 0.5 per Al atom must be assumed on the montmorillonite surface. Assuming that the hydroxy-aluminum form in the unreacted solution is Al6(OH)3+12, the adsorbed polymer will be Al24(OH)12+60. Alternatively, assuming Al6(OH)3+15 in the unreacted solution, this form will remain unchanged upon adsorption onto the montmorillonite surface.

Differences in the microfabric of dry Al-CLM as a function of Al/montmorillonite ratio can be explained along the lines of the interpretation of the flocculation studies.
Characterization of the Particle Size and the Crystallinity of Certain Minerals by IR Spectrophotometry and other Instrumental Methods—II. Investigations on Quartz and Feldspar
Authors: Hlavay J. , Jonas K. , Elek S. , Inczedy J.
Published: August 2006

Infrared spectra of two minerals; Urkut quartz (Hungary) and a Swedish feldspar, of different origin with different physical characteristics and crystallinity were studied. Samples were taken after appropriate grinding, and infrared spectra, X-ray powder diffraction and water vapor absorption measurements were made along with electronmicrographs. Quantitative conclusions were drawn from changes of particle size and the ratio of bands of the Si—O groups and also the degree of crystallinity and changes of the particle size, respectively.
Intercalation of Salts in Halloysite
Authors: Carr R. M. , Chaikum N. , Patterson N.
Published: August 2006

Several new salt intercalation complexes of halloysite have been prepared and characterized using X-ray powder diffraction techniques taking into account both the position and the shape of the d001 peaks. The amount of intercalated ion in some fully complexed halloysites has been directly determined using conventional analytical techniques. The results show that less than half of the theoretical amount of salt is intercalated into the clay; the amount of salt depending on its nature and, where hydrolyzable ions are present, on the pH. Infrared spectra taken of some complexes give an indication of the nature of the interaction within interlayer space and elsewhere. The interactions are weak and are either dipolar attractions or hydrogen bonds. The ions which show the greatest tendency to intercalate with halloysite are water structure-breaking cations or hydrogen-bonding anions.
Flint-Clay Facies Illustrated within One Deposit of Refractory Clay
Authors: Keller W. D.
Published: August 2006

The flint-clay facies, originally proposed from widespread stratigraphie evidence, is represented by four of its six members within a single commercial deposit of Cheltenham refractory clay in Missouri. Scan electron micrographs show progressive changes in texture from plastic refractory clay (as in ball-clay “swirl” texture) through semi-plastic, semi-flint, to typical flint clay (recrystallized, well-ordered kaolinite). Micrographic evidence supports the interpretation of the origin of the Cheltenham clay earlier made from field and macroscopic evidence. Source material from nearby residual, weathered clay was transported into paludal basins, “digested,” partly recrystallized to kaolinite, brecciated and reconsolidated, essentially completed before being covered by younger Pennsylvanian-age sediments.
The I.R. Spectra of Dimethyl Sulfoxide Adsorbed on Several Cation-Substituted Montmorillonites
Authors: Garwood G. A. , Condrate R. A.
Published: August 2006

The i.r. spectra (4000-1200 cm-1) are obtained for several homoionic montmorillonite films on which various amounts of dimethyl sulfoxide (DMSO) were adsorbed. Analyses of these spectra indicate that H- and natural-montmorillonite-DMSO complexes contain an intercalated layer of physisorbed DMSO while transition metal cation substituted-montmorillonite-DMSO complexes possess both physi- and chemisorbed DMSO in their interlamellar spaces. The latter species involve coordination of DMSO molecules with the exchangeable cations by their oxygen atoms. Most of the interlamellar water is replaced by DMSO as the latter molecules penetrate the interlamellar spaces. Heat-treating transition metal cation substituted-montmorillonite-DMSO complexes at 120°C for 48 hr results in both the desorption of physisorbed DMSO and the retention of intercalated monolayers involving DMSO-transition metal cation coordination. A water-sensitive, reversible color change (tan to light purple) is produced by either desiccating over P2O5 or heat-treating at 120°C the cobalt-montmorillonite-DMSO complex. Interpretation of the visible spectra suggests that Co2+-cations undergo changes from octahedral to tetrahedral coordination during desiccation or heating. Band assignments are made for the clay complexes using the assignments for related gases, liquids, and crystals.
The Exchange of Alkylammonium Ions on Na-Laponite
Authors: Vansant E. F. , Peeters G.
Published: August 2006

The exchange of various alkylammonium cations from aqueous solution by sodium laponite has been studied. The affinity of the clay for these organic cations was linearly related to the molecular weight, molecular size or chain length of the alkylammonium ions. The affinity for the clay increases regularly with increasing chain length of the primary amines. A comparison of primary, secondary, and tertiary amines, containing the same alkylgroups shows that the affinity increases in the order R1NH3+ < R2NH2+ < R3NH+. These affinity sequences were attributed to important van der Waals contributions and changes in ion hydration states. The thermodynamic excess function, ΔGmE, was calculated and indicated that with respect to the pure homoionic forms the heterogeneous Na+-alkylammonium surface phases were more stable than they would be if the mixing were ideal.
The Adsorption of N-Aliphatic Alcohols from Dilute Aqueous Solutions on RNH3-Montmorillonites. Part I. Distribution at Infinite Dilution
Authors: Stul Michel S. , Maes André , Uytterhoeven Jan B.
Published: August 2006

The adsorption of butanol, hexanol, and octanol on alkylammonium clays of different chain length is studied. The adsorption at infinite dilution compares to the distribution of alcohol between alkane and water in bulk solution. The interlamellar phase of the montmorillonite acts as a solvent even more reactive than carbon tetrachloride. Hydrogen bonds probably occur between the OH group of the alcohol and the NH3+ group. The exchange of water by alcohol on the interlamellar alkylammonium ion is the major factor in the transfer process.
Reaction Series for Dioctahedral Smectites
Authors: Eberl Dennis
Published: August 2006

Several dioctahedral clay minerals are related through reaction series. These series can be produced hydro-thermally from beidellite gel and montmorillonite by making simple changes in interlayer and solution chemistry. The series are:

gel-K-beidellite-random illite/smectite-K-rectorite-illite

K-montmorillonite-K-rectorite-illite

Na-montmorillonite or beidellite-Na-rectorite-paragonite

Li-montmorillonite-Li-tosudite-Li-rectorite-cookeite(?)

Mg-montmorillonite-Mg-rectorite-tosudite-sudoite(?)

Ca-montmorillonite-Ca-rectorite-margarite(?)

Al-Ca-montmorillonite-kaolinite/smectite-kaolinite (150°C)

Al-Ca-montmorillonite-pyrophyllite/smectite-pyrophyllite (320°C).

Assuming stability for the mixed-layer phases, paragenesis is a function of P, T, and X conditions. If the phases are considered to be metastable, paragenesis is a function of the speed and path of reaction.
Dissolution of Smectites in Hydrochloric Acid: II. Dissolution Rate as a Function of Crystallochemical Composition
Authors: Novák I. , Číčel B.
Published: August 2006

A correlation was made of crystallochemical data from 15 smectites with the half time of dissolution (t05) in 6 N hydrochloric acid at 96°C. From this the relation

ln t05 = 3.95 - 1.96 FeVI - 2.30 MgVI

was developed. It shows a remarkable dependence of the apparent dissolution rate of the octahedral layer of the smectites on the substitution of Fe3+ and Mg2+ for Al+3 in the octahedral position.
A Comparison of the Effectiveness of Eight Methods for the Removal of Organic Matter from Clay
Authors: van Langeveld A. D. , van der Gaast S. J. , Eisma D.
Published: August 2006

Organic matter present in clayey sediments may act as a cement between the clay particles as well as a blocking agent for the swelling of clay minerals like montmorillonite.

Removal of the organic matter is important when a clay sample is to be characterized by X-ray powder diffraction, or when it is to be separated into the composing minerals on the basis of differences in density.

Eight different methods for the removal of organic matter from a North Sea clay sample have been studied. Of all methods tried bromine oxidation was found to be the most effective.
Reactions of Zinc with Acid and Base Saturated Dickites
Authors: Singhal J. P. , Gupta G. K.
Published: August 2006

The effect of pH, time and temperature on the interaction of zinc with acid and base saturated dickites has been investigated. Increase in pH resulted in an increase in adsorption of zinc in the higher concentration range. The adsorption increased rapidly and then slowly with increase in the time of interaction. The variation of rate constants and the half times of reaction suggested an exchange process controlled by film and possibly particle diffusion and thereafter fixation processes. The inferences found support from the nature of adsorption isotherms. Temperature affected adsorption with exothermic interactions. The activation energy of adsorption of zinc on Na-dickite was 14.0 kcal mole−1.
Kaolinite Synthesis. I. Crystallization Conditions at Low Temperatures and Calculation of Thermodynamic Equilibria. Application to Laboratory and Field Observations
Authors: La Iglesia A. , Van Oosterwyck-Gastuche M. C.
Published: August 2006

The equilibrium diagrams developed for Al-hydroxide and for kaolinite by Garrels and Christ (1965) have been modified by taking into account the existence of gels. From the stability zones obtained, the “appropriate” concentrations can be deduced and utilized for synthesizing these species, provided the requirements to insure good crystal growth are observed. Among procedures to promote these crystallizations, homogeneous precipitation processes (La Iglesia et al., 1974, 1976) appear to be particularly adequate.

The theoretical considerations provide an explanation for most of the processes observed until now, both successful and unsuccessful syntheses, and also give an explanation for many field observations. The crystallizations, however, remain poorly reproducible, indicating that many factors are still poorly known. Some points requiring further investigation include (i) better values for ΔGr0, (ii) the influence of organic complexes, (iii) the effect of preexisting crystalline phases, (iv) those involving dehydration processes in these systems.
Quantitative Clay Mineralogical Analyses from the Bulk Chemistry of Sedimentary Rocks
Authors: Pearson Mike J.
Published: August 2006

A technique suitable for computer application has been developed whereby whole rock major element analyses are corrected for X-ray detectable nonclay minerals and used to set up simultaneous equations which are solved to give clay mineral abundances. A theoretical evaluation of the approach by graphical methods enables the intrinsic errors to be very clearly assessed. Errors are minimized when SiO2, A12O3, and K2O are used as variables but only slightly increased if total Fe2O3 + MgO is substituted for SiO2. Quartz and CO2 content are the only data normally required which cannot be determined by X-ray fluorescence.

Results compare favorably with estimates obtained by XRD and other methods, being more accurate than XRD and equally precise provided the rock does not contain clay minerals other than the kaolin group, the mica group, and chlorite. Errors are large when the clay mineral phases comprise more than 35% chlorite and as yet undetermined when smectite exceeds 10%.

The method is ideally suited to the analysis of large numbers of mudstones of fairly similar mineralogy especially where XRF equipment with direct output to a computer is available.
Adsorption of N2, O2, CO2 and H2 on Hydrotalcite-Like System: Mg2+-Al3+-(Fe(CN)6)4−
Authors: Miyata Shigeo , Hirose Toru
Published: August 2006

The compound Mg2+-Al3+-(Fe(CN)6)4−, with a structure similar to hydrotalcite Mg6Al2(OH)16CO3 ·4H2O, is prepared by a coprecipitation method. Chemical, thermal, and X-ray analysis of the compound lead to the formula: <mml:math xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:mnf="http://cambridge.org/core/manifest" xmlns:cup="http://contentservices.cambridge.org" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:m="http://cambridge.org/core/metadata" xmlns:core="http://cambridge.org/core" xmlns:c="http://cambridge.org/core/content">(Mg0.741Al0.259(OH)2)((FeII(CN)6)0.067(CO3)0.002(H2O)1.05)

The compound is dehydrated at 100° to 250°C, and the adsorption of N2, O2, CO2, and H2 on it is measured at −196°C to room temperature by the volumetric method. The water is removed reversibly from 100° to 200°C, and the interstices after dehyration act as sites of adsorption. When dehydration is carried out at 150°C, the adsorptive activity reaches a maximum. Adsorption isotherms of N2 and O2 at −196°C and of CO2 at room temperature are of the Langmuir type, and the saturated amounts of N2, O2, and CO2 adsorbed are 96.3, 65.2, and 91.8 ml (STP)/g, respectively.

Adsorption isotherms of N2 and O2 at room temperature are of the Henry type. The amount of O2 adsorbed is about 67% of that of N2. The isosteric heats of adsorption at room temperature of N2, O2, and CO2 are 5.1, 4.8, and 11.0 kcal/mol, respectively. A dehydrated product of a Mg2+-Al3+-CO32− compound does not permit adsorption of CO2 at room temperature, but permits the adsorption of H2O. Hence, it has a molecular sieve effect. No adsorption of H2 is observed in any of the compounds tested.
Morphology and Structure of Halloysite in New Zealand Tephras
Authors: Kirkman John H.
Published: August 2006

As shown by scanning and transmission electron microscopy, halloysite in three rhyolitic tephras occurs as squat and elongate ellipsoids. Both morphologies are presumed to result from a similar lattice building mechanism. The squat ellipsoids form from allophane; the elongate ellipsoids form from feldspars. The squat ellipsoids do not possess flattened faces or spaces between books of layers at field moisture levels. Outgrowths from the squat ellipsoids are possibly due to inclusions of allophane, glass, ferrihydrite, or feldspar crystallites. Possible spiral growth of halloysite, giving curved surfaces, may be due to a continuous distribution of crystal dislocations.
Dissolution Kinetics of Phlogopite. II. Open System Using an Ion-Exchange Resin
Authors: Clemency Charles V. , Lin Feng-Chih
Published: August 2006

The rate of dissolution of phlogopite in an open system was measured at low temperature and pressure and at pH 3–5. The maximum dissolution rate was achieved by maintaining extremely low ionic concentrations in the solution using a cation-exchange resin (hydrogen form) as a trap for released cations. The resin also served as a source of hydrogen ions and acted as a buffer. The concentrations of ions adsorbed on the resin and remaining in solution were measured, along with surface area and cation-exchange capacity. The amount of phlogopite dissolved after 1010 hr was 67 times that dissolved using a CO2-buffered, closed-system method. During the first hour of the experiment, dissolution was incongruent, but later became congruent from 1 to 1010 hr. From 1 to 200 hr the reaction had linear kinetics. The dissolution rate for the first 200 hr of the reaction was 2.0 × 10−14 mole KMg3AlSi3O10(OH)2/cm2/sec. Since no evidence of parabolic kinetics was found, there is no reason to postulate the formation of a “protective layer.”
Smectite to Illite Conversion Rates: Effects of Solution Chemistry
Authors: Roberson Herman E. , Lahann Richard W.
Published: August 2006

Mixed-layer illite/smectite (I/S) was formed by reacting the Chambers or Polkville montmorillonite hydrothermally at 270° and 350°C from several hours to more than 15 weeks. Reactions were conducted in closed vessels containing K or mixed K-Na, K-Ca, or K-Mg solutions of varying concentrations. The reaction rate and the rate of ordering of I/S for the reaction smectite + K+ → mixed-layer I/S + SiO2 was inhibited by the addition of Na+ Ca2+, and Mg2+; the inhibitory strength of Na+, Ca2+ and Mg2+, on an equivalent basis, increased approximately in the ratio 1:10:30. The first order reaction-rate constants for the reactions at 270° and 350°C indicate an activation energy of about 30 kcal/mole.

In the experimental system studied, the reaction smectite → mixed-layer I/S appeared to proceed by solid state transformation, as suggested by: (1) rapid dissolution of large amounts of silica, probably creating an Al-enriched residue; (2) similarity of particle size and morphology of the mixed-layer products to those of the original montmorillonite, implying no extensive dissolution of Al3+; and (3) relatively high activation energy compared to published values for silicate dissolution.
Determination of Tetrahedral Substitutions and Interlayer Surface Heterogeneity from Vibrational Spectra of Ammonium in Smectites
Authors: Chourabi B. , Fripiat J. J.
Published: August 2006

Integrated intensities of the fundamental modes of vibrations of ammonium in heat-treated, NH4+-exchanged swelling minerals permits (1) a quantitative determination of the amount of tetrahedral substitutions of Si4+ by M3+ in dioctahedral smectites, and (2) an estimate of the degree of interlayer surface heterogeneity in trioctahedral minerals to be made. This is possible because NH4+ cations balancing the negative charge of tetrahedral sites that are not influenced by an excess positive charge of the octahedral layer have a symmetry lower (probably C3v) than the usual tetrahedral Td symmetry of NH4+. In C3v symmetry the ν1 band is infrared active whereas it is only Raman active in Td symmetry. Protons left after deammoniating dioctahedral smectites with tetrahedral substitutions form interlayer silanol groups, the stretching vibration of which give a band that is distinct from that of octahedral OH-stretching modes.
Composition and Origin of Smectite in Soils Derived from Basalt in Northern Ireland
Authors: Curtin D. , Smillie G. W.
Published: August 2006

The sand and silt fractions of soils derived from Tertiary basalt in northeastern Ireland exhibit unusually high cation-exchange capacities. Smectite was identified by X-ray powder diffraction in all size fractions and was selectively dissolved by treatment with 1 N HCl and 0.5 N NaOH. Structural formulae, based on chemical analysis of the dissolved material, suggest that the smectite is intermediate in composition between a di- and a trioctahedral mineral and that the octahedral cation occupancy, together with the numbers of Mg and Fe atoms per unit cell, decreases with decrease in particle size of the soil fraction examined. The mean formula for the smectite in the clay separates is:

M+0.40(Si3.33Al0.67)(Al1.07Fe2+0.09 Fe3+0.41Mg0.82)O10(OH)2.

Similar analysis of smectite present in clay-size material separated from weathered basalt rock taken from the bases of the soil profiles showed that it had close to the full trioctahedral occupancy. It is suggested that the soil smectite is a weathering product of the trioctahedral smectite inherited from the weathered basalt.
Preparation and Electrical Properties of Quaternary Ammonium Montmorillonite-Polystyrene Complexes
Authors: Kato Chuzo , Kuroda Kazuyuki , Takahara Hideyuki
Published: August 2006

Intercalation compounds of styrene and quaternary ammonium montmorillonite were prepared by immersion of the clay in styrene monomer. The intercalation of stearyltrimethylammonium (CH3(CH2)17N(CH3)3+)-montmorillonite and styrene showed an expansion of the basal spacing to a constant value of ∼32 Å after immersion for 10 days. After polymerization, the amount of polystyrene in the interlayer region was determined by thermal gravimetric analysis. Styrene adsorption initially increased with increasing quaternary ammonium cation and then became approximately constant when loading of the quaternary ammonium cation exceeded 100 meq/100 g clay. The volume resistivity of the stearyltrimethylammonium-montmorilionite-polystyrene complex, which was determined with a high resistance meter, was greater than that of both the quaternary ammonium-montmorillonite and the montmorillonite, and increased in proportion to the amount of polymer adsorbed. These data indicate that polystyrene improved the insulating properties of the clay films.
Hydrothermal Formation of a Kaolinite-Like Product from Noncrystalline Aluminosilicate Gels
Authors: De Kimpe C. R. , Kodama H. , Rivard R.
Published: August 2006

Noncrystalline aluminosilicate gels with Al2O3/(Al2O3 + SiO2) weight ratios from 0.3 to 0.5 were reacted in 0.1 N KOH at temperatures varying from 125° to 175°C. The pH of the solutions dropped sharply with increasing gel:solution ratios, indicating that the coordination number of Al in the products changed from IV to VI. The degree of hydrolysis appeared to be higher with KOH than with NaOH. X-ray powder diffraction and infrared spectroscopy showed that disordered kaolinite was the only crystalline product formed. Thermal data and surface area measurements indicated that the kaolinite was formed by a condensation process.