bluuebunny/crossref_metadata_2025_split huggingface dataset:
Low-Temperature Hydrothermal Alteration of Trachybasalt at Conical Seamount, Papua New Guinea: Formation of Smectite and Metastable Precursor Phases
Authors: Giorgetti Giovanna , Monecke Thomas , Kleeberg Reinhard , Hannington Mark D. 
Published: January 2010

AbstractThe conversion of volcanic glass to secondary alteration products is one of the most common mineralogical transformations during low-temperature hydrothermal alteration of submarine basalts. To better understand the mechanism and kinetics of this transformation, porphyritic and formerly glassy trachybasalt, recovered from Conical Seamount, Papua New Guinea, was studied in detail. Low-temperature interaction of trachybasalt with hydrothermal fluids at this submerged volcano occurred in response to the formation of submarine epithermal-style gold mineralization. Alteration of the coherent volcanic rocks is heterogeneous with pronounced differences in alteration intensity occurring between igneous minerals and the surrounding glassy groundmass. In comparison to the volcanic glass, the crystalline phases were less prone to hydrothermal alteration with the alteration susceptibility decreasing from clinopyroxene through biotite to feldspar. Low-temperature alteration of clinopyroxene resulted in the formation of abundant saponite-like smectite with no topotactic relationship being observed between the two phases. In contrast, the conversion of biotite to smectite involved structural inheritance as the orientation of common structural blocks was maintained during alteration. Transmission and analytical electron microscopy revealed that pervasive alteration of interstitial glass in the groundmass of the trachybasalt resulted in the formation of montmorillonite- and saponite-like smectite whereby smectite composition is strongly influenced by the glass chemistry. The occurrence of poorly crystalline domains with a 0.3 to 0.4 nm layer spacing in the altered interstitial glass suggests that the transformation of glass to smectite involved the formation of a transitional alteration product. Comparison with the results of previous studies highlights the fact that the glass-to-smectite transformation can proceed through more than one reaction pathway. Reaction style and reaction progress are controlled by kinetic factors such as the mode of fluid transport triggering alteration in the low-temperature hydrothermal environment. Alteration of the trachybasalt at Conical Seamount is inferred to have taken place at a comparably low fluid-rock ratio as the low permeability and the absence of primary fractures and joints restricted fluid circulation through the coherent volcanic rocks.
Crystal-Chemical Changes of Mixed-Layer Kaolinite-Smectite with Progressive Kaolinization, as Investigated by TEM-AEM and HRTEM
Authors: Cuadros Javier , Nieto Fernando , Wing-Dudek Teresa 
Published: January 2010

AbstractThe mechanism for the kaolinization of smectite is extremely complex. The purpose of this study was to explore this mechanism by providing more microscopic information about kaolinite-smectite (K-S) intermediate phases. Crystal-chemical changes were investigated and integrated in a model of the transformation mechanism. Eight K-S samples from three localities, derived from volcanic ash beds, were studied using transmission and analytical electron microscopy (TEM, AEM) and high-resolution TEM (HRTEM). The study completes a previous investigation, using several analytical techniques. The samples cover the range of K-S composition available from the previously studied sample set. Analysis by TEM indicated the preservation of particle morphology throughout the process. Most K-S particles had anhedral, smectite-like morphology, and only the most kaolinitic specimen revealed the coexistence of anhedral and euhedral, hexagonal particles. Analytical electron microscopy showed large chemical variations within samples, corresponding to various degrees of smectite kaolinization. Comparison of chemical results (Si/Al) and d060 values (proxy for octahedral composition) with the extent of kaolinization from thermogravimetry (TG) indicates that chemical changes in the octahedral sheet occur mainly when the proportion of kaolinite is 40–70%. The results above are consistent with kaolinization occurring via layer-by-layer transformation through the progressive loss of individual tetrahedral sheets in smectite layers and subsequent chemical changes in the octahedral sheet. Such a mechanism would produce the results observed in this study: (1) most particles preserve their original morphology; (2) significant variation in terms of the extent of transformation of particles within samples, and (3) formation of crystal structures intermediate between those of smectite and kaolinite, with parts of the tetrahedral sheets missing (kaolinite-like patches). Such structures become least stable at kaolinite ∼50%, when the perimeter of the kaolinite-like patches is largest and chemical changes in the octahedral sheet can occur more easily. Kaolinite layers could not be resolved by HRTEM in most cases and showed lattice fringes corresponding to superstructures. A model was established to quantify kaolinite and smectite layers in the HRTEM images with results which matched TG-derived values.
Rapid Dehydroxylation of Nickeliferous Goethite in Lateritic Nickel Ore: X-Ray Diffraction and TEM Investigation
Authors: Landers Matthew , Gilkes Robert J. , Wells Martin A. 
Published: January 2010

AbstractA method for extracting Ni and other metals from lateritic ores by means of shock heating has been investigated. Shock heating releases some of the metal from its goethitic host. Even though the transformation of pure goethite to hematite is known to occur via intermediate hydroxylated phases, the effect of other metals such as Ni substituting for Fe in goethites on this thermal transformation to hematite is unknown. The purpose of this study was to fill this gap, with the hope that the results will lead to more energy-efficient extraction methods and/or a better understanding of Fe geochemistry in thermally activated soils. X-ray diffraction, transmission electron microscopy with EDS, and thermal analysis were used to investigate mineralogical changes in nickeliferous goethites from five oxide-type lateritic nickel ore deposits that had been subjected to shock heating at temperatures in the range 220–800°C. Acicular, nano-sized goethite was the main constituent of the samples with minor to trace amounts of quartz, talc, kaolinite, chromite, maghemite, and Mn oxides. Goethite was partially dehydroxylated to OH-hematite at 340–400°C and had completely altered to well ordered hematite at 800°C. The OH-hematite was characterized by broad XRD peaks for reflections associated with the Fe sublattice. The goethite unit-cell a and b lengths remained almost constant with increasing preheating temperature up to 300°C, while the size of the c axis dimension contracted. The neoformed hematite crystals were larger than the precursor goethite crystals due to development, by sintering and surface diffusion, of regularly ordered hematite domains. The increase (1.5–2.6 fold) in surface area with increasing heating temperature (up to 340–400°C) reflected the development of slit-shaped micropores (∼300°C), which further developed into elliptically shaped micropores (∼400°C) in OH-hematite. With increased heating temperature, well ordered hematite formed with only a few micropores remaining. Such results may contribute to the development of more efficient procedures for extracting Ni from lateritic nickel ores, as the rate of dissolution of goethite in acid in ‘heap and pressure’ leach facilities will be enhanced by the increases in surface area and microporosity. The results may also provide valuable information on the probable effects of natural heating on pedogenic Fe oxides.
Kaolinite Intercalation Precursors
Authors: Li Yanfeng , Sun Dewen , Pan Xiaobing , Zhang Bo 
Published: January 2010

AbstractThe preparation and characterization of intercalated kaolinite is important for industries such as those using nanocomposites, but the number of compounds that can be intercalated into these clay minerals is rather limited. The purpose of this study was to expand the range of possible intercalants by developing intercalation precursors using both single and multiple (co-intercalation) precursor agents. Characterization of the resulting precursors was by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and differential thermal analysis (DTA). The results show that the most successful single intercalation agent was DMSO and, among the co-intercalation agents, the DMSO/CH3OH system was the best. The preparation and characterization of kao-DMSO-KAc showed that the displacement reaction is the most efficient way to expand the interlayer spacing of kaolinite. At the same time, the lateral-bilayer arrangement of the Ac− in the interlayers was proven by study of de-intercalation of kao-KAc under high temperature.
Peer tutoring in reading: The effects of role and organization on two dimensions of self‐esteem
Authors: Miller David. , Topping Keith. , Thurston Allen. 
Published: January 2010

BackgroundPaired reading (PR) is an application of peer tutoring. It has been extensively researched, and its efficacy across a range of outcomes has been established. Benefits include improvements in key reading skills, and also in affective aspects of learning. Several studies have shown gains in self‐esteem, although measurement methods have varied, and the model of self‐esteem has rarely been clearly articulated.AimsTo investigate the changes in self‐esteem of children participating in a randomized trial of PR over a 15‐week treatment period. To investigate the relative contribution of self‐worth and self‐competence to any gains in self‐esteem. To investigate whether the pattern of change differs in children who take on different roles in the PR process.ParticipantsThe participants comprised a subset of a large‐scale randomized trial of peer learning (The Fife Peer Learning Project). Four schools were randomly selected from schools allocated to the same‐age PR condition, and four schools from those allocated to the cross‐age PR condition. The same‐age group consisted of 87 primary 6 children (10–11 years old). The cross‐age group consisted of 81 primary 6 children. The controls, from schools randomly selected from a neighbouring authority, consisted of 92 primary 6 children.MethodA pre–post design employing self‐report measures of self‐esteem. Rosenberg's Self‐Esteem Scale was used, with scores analysed for worth and competence. The treatment period was 15 weeks, with the participants following a prescribed PR process.ResultsSignificant pre–post gains were noted in self‐esteem, driven predominantly by improved beliefs about competence, in both same‐age and cross‐age conditions, but not for controls. Gains were also seen in self‐worth in the cross‐age condition. Further analyses of the influence of organizational condition (same‐age or cross‐age) and role played (tutor vs. tutee) showed significant differences between same‐age tutors and cross‐age tutors in relation to self‐worth. Effect sizes were generally small or moderate.ConclusionsThe findings provide further support for the belief that PR can enhance self‐esteem. Importantly, the use of a two‐dimensional model provides extra information about self‐perceptions in PR contexts: first, the central role of self‐competence; and second, the gains in self‐worth which are associated with tutoring younger children (but not same‐age peers). This new information has educational significance for schools considering the potential of peer tutoring and the benefits of different organizational conditions.
Measurement of surface growth stress in Eucalyptus nitens Maiden by splitting a log along its axis
Authors: Chauhan Shakti , Entwistle Kenneth 
Published: January 2010

Abstract
When a log is sawn along the length, an outward bending or deflection of two half rounds arises from the release of growth stresses in the log. The relationship between this outward bending and the peripheral longitudinal growth strain in logs from a 10-year-old Eucalyptus nitens plantation was investigated. In total, 63 trees were felled and two logs (one bottom and an upper log) were cut from each felled tree. A strong association was observed between the measured longitudinal growth strain and the outward bending produced by splitting the log along its axis. A mathematical model was developed that enables calculation of the relationship between the surface axial growth stress and the opening of the split log. This involves calculation of the lateral deflection of a tapered cantilever beam of semi-circular cross-section under a known bending moment. The relationship between the opening of the slit log and the surface axial stress showed good agreement with the measured data on 126 logs. The model equation is effective in predicting the growth stress from the magnitude of the log distortion. This log sawing or splitting method is quick and reliable for assessing the surface growth stresses in small diameter trees. It could have potential in breeding programs for identifying families or clones for low-growth stresses of superior eucalypts for sawn timber production.
Studies on the dehydrogenative polymerization of monolignol β-glycosides. Part 6: Monitoring of horseradish peroxidase-catalyzed polymerization of monolignol glycosides by GPC-PDA
Authors: Tobimatsu Yuki , Takano Toshiyuki , Kamitakahara Hiroshi , Nakatsubo Fumiaki 
Published: January 2010

Abstract
Horseradish peroxidase (HRP)-catalyzed dehydrogenative polymerization of guaiacyl (G) and syringyl (S)-type monolignol γ-O-glucosides, isoconiferin (iso-G) and isosyringin (iso-S), which contain a hydrophilic glucosyl unit on γ-position of coniferyl alcohol and sinapyl alcohol, respectively, was monitored by gel permeation chromatography coupled with photodiode array detection (GPC-PDA). Contrary to the conventional dehydrogenative polymerization of monolignols, the polymerization of the glycosides produces water-soluble synthetic lignins (DHPs) in a homogeneous aqueous phase. Taking advantage of this unique reaction system, the method was developed to follow the changes of molecular weights in the course of DHP formations. Moreover, PDA detection permits determination of oligomeric S-type quinone methide intermediates (QMs) formed as stable transient compounds during polymerization of iso-S. A detailed comparison of the polymerization profiles revealed entirely different behaviors of G- and S-type monomers. The data strongly support the view that the low reactivity of oligomeric S-type QMs impedes the formation of DHPs from S-type monomers. In copolymerization of G- and S-type monomers, it is conceivable that G-type phenolic hydroxyl groups serve as good nucleophilic reactants to scavenge S-type QMs resulting in efficient production of DHPs. As a consequence, the present approach can be a powerful tool to study the in vitro dehydrogenative polymerization providing further mechanistic insights into lignin polymerization in vivo.
Determination of the change in appearance of lumber surfaces illuminated from various directions
Authors: Nakamura Masashi , Matsuo Miyuki , Nakano Takato 
Published: January 2010

Abstract
Optical appearance is an important aesthetic property of wood, and this unique visual characteristic needs to be described quantitatively for many industrial applications. The objective of this study is to demonstrate the change in appearance of lumber surfaces from the viewpoint of human observation. Ten different specimens of coated and uncoated fancy veneer overlaid plywood of four species and solid and print Sugi (Japanese cedar) boards were prepared. For observation purposes, a simple goniophotometric device was constructed. A series of digital images of each specimen was taken, whereas the surface was illuminated from various lighting azimuths. The images were evaluated by subtraction, correlation, and multiresolution contrast analyses. The first two methods detect reflection anisotropy on the specimen surface through comparison of two images. Subtraction analysis also distinguishes between the coated and uncoated surfaces. However, it is difficult to determine the difference between the solid and print Sugi specimens based on these techniques. By contrast, multiresolution contrast analysis renders possible evaluation of the size and degree of the change in the surface appearances by contrast values. By comparing the contrast values for every lighting azimuth and filter size, this analysis clearly determines the change in appearance peculiar to wood, such as reflection anisotropy, improvement in reflectiveness conferred by coating, and the difference between the solid and print Sugi specimens.
Thermal aging of 1-alkyl-3-methylimidazolium ionic liquids and its effect on dissolved cellulose
Authors: Liebner Falk , Patel Ilabahen , Ebner Gerald , Becker Ernst , Horix Michael , Potthast Antje , Rosenau Thomas 
Published: January 2010

Abstract
The thermal degradation products of 1-alkyl-3-methyl-imidazolium-type ionic liquids (e.g., BMIM, EMIM), which are commonly used in cellulose chemistry, were identified. Imidazole (5), N-methylimidazole (6), and N-alkylimidazoles (7, 8) are the main products. Moreover, dimeric substituted imidazoles (9–11) were found carrying a methylene bridge formed from the N-methyl structure. The former 1-alkyl group (butyl or ethyl) was not present in any of the dimeric compounds. The N-methylene intermediate (12) acts as a precursor for the substituted imidazoles linked by a methylene group. All thermal degradation products are bases and catalyze the previously described reaction between the reducing end of celluloses and 1-alkyl-3-imidazolium cations. To minimize this side reaction, ionic liquids have to be liberated from such basic compounds prior to application as cellulose solvents. In this regard, the usage of “recycled” (and unpurified) ionic liquids has to be treated with caution.
Extractives of the tropical wood wallaba (Eperua falcata Aubl.) as natural anti-swelling agents
Authors: Royer Mariana , Stien Didier , Beauchêne Jacques , Herbette Gaëtan , McLean J. Paul , Thibaut Anne , Thibaut Bernard 
Published: January 2010

Abstract
Wallaba (Eperua falcata) is a tropical wood that is known to have naturally high moisture related dimensional stability. Samples of wallaba heartwood were subjected to differential solvent extraction. Wood pieces that were extracted with methanol showed significantly greater swelling following rehydration from oven dry to 96% relative humidity than non-extracted samples and samples extracted with other solvents. Methanol soluble wallaba heartwood extract was purified by HPLC and the compounds present were characterized by NMR spectroscopy. The structure of 13 compounds in methanol extract was identified. The relative proportion of polar compounds in methanol extract was found to be high. The compounds identified are proposed to bind to the polymeric cell wall by means of multiple hydrogen bonds restricting the association of water and therefore act as natural anti-swelling agents.
Preparation of thermoplastic molding from steamed Japanese beech flour
Authors: Takahashi Isoko , Sugimoto Takanori , Takasu Yasuo , Yamasaki Mariko , Sasaki Yasutoshi , Kikata Youji 
Published: January 2010

Abstract
Thermoplastic molding has been prepared from beech wood flour steamed at 180°C or at higher temperatures without any additives. It exhibited a smooth and lustrous surface and had a high density of approximately 1.45 g cm-3. The internal structure of molding revealed that the flour particles were completely surrounded by black resin-like substance which was thermoplasticized by heat and pressure during the molding process. The chemical composition of the steamed flour and physical properties of molding were examined as a function of steaming temperature. Maximum bending strength and Young's modulus of molding reached 63 MPa and 11 GPa, respectively, at 180°C of steaming, which were much higher than those of a hardboard. The water absorption of the molding was 8% or less and decreased with the steaming temperature.
Absence of major fibrotic adverse events in hyperprolactinemic patients treated with cabergoline
Authors: Lafeber M , Stades A M E , Valk G D , Cramer M J , Teding van Berkhout F , Zelissen P M J 
Published: January 2010

BackgroundCabergoline, a dopamine agonist used to treat hyperprolactinemia, is associated with an increased risk of fibrotic adverse reactions, e.g. cardiac valvular fibrosis, pleuropulmonary, and retroperitoneal fibrosis.ObjectiveThis study evaluated the prevalence and risk of fibrotic adverse reactions during cabergoline therapy in hyperprolactinemic and acromegalic patients.DesignA cross-sectional study was conducted in a University Hospital.PatientsA total of 119 patients with hyperprolactinemia and acromegaly who were on cabergoline therapy participated in the study.MethodsAll patients were requested to undergo a cardiac assessment, pulmonary function test, chest X-ray, and blood tests as recommended by the European Medicine Agency. Matched controls were recruited to compare the prevalence of valvular regurgitation. Cardiac valvular fibrosis was evaluated by assessing valvular regurgitation and the mitral valve tenting area (MVTa). The risk of pleuropulmonary fibrosis was assessed by a pulmonary function test, a chest X-ray, and if indicated, by additional imaging studies.ResultsThe prevalence of clinically relevant valvular regurgitation was not significantly different between cases (11.3%) and controls (6.1%; P=0.16). The mean MVTa was 1.27±0.17 and 1.24±0.21 cm2 respectively (P=0.54). Both valvular regurgitation and the MVTa were not related to the cumulative dose of cabergoline. A significantly decreased pulmonary function required additional imaging in seven patients. In one patient, possible early interstitial fibrotic changes were seen. Lung function impairment was not related to the cumulative cabergoline dose.ConclusionCabergoline, typically dosed for the long-term treatment of hyperprolactinemia or acromegaly, appears not to be associated with an increased risk of fibrotic adverse events.
Fluorites: Superionics and Conduction Processes
Authors: Hull Stephen 
Published: January 2010

AbstractThe superionic conducting properties of fluorite structured compounds are discussed in this paper, starting with a brief historical overview of the topic. The current state of knowledge concerning the dynamic lattice disorder associated with the high values of ionic conductivity is summarized and illustrated using three examples taken from the author’s research program. These are chosen to highlight different aspects of the structure-property relationships within fluorite-structured superionics and, in particular, demonstrate the role of the neutron diffraction technique in investigations of compounds showing high levels of ionic conductivity. The paper concludes with an overview of some current developments within this research field.