bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Background Colors on the Tuning of Color-Selective Cells in Monkey Area V4
Authors: Kusunoki Makoto , Moutoussis Konstantinos , Zeki Semir
Published: April 2006

When objects are viewed in different illuminants, their color does not change or changes little in spite of significant changes in the wavelength composition of the light reflected from them. In previous studies, we have addressed the physiology underlying this color constancy by recording from cells in areas V1, V2, and V4 of the anesthetized monkey. Truly color-coded cells, ones that respond to a patch of a given color irrespective of the wavelength composition of the light reflected from it, were only found in area V4. In the present study, we have used a different approach to test the responses of V4 cells in both anesthetized and awake behaving monkeys. Stimuli of different colors, embedded within a Mondrian-type multicolored background, were used to identify the chromatic selectivity of neurons. The illumination of the background was then varied, and the tuning of V4 neurons was tested again for each background illumination. With anesthetized monkeys, the psychophysical effect of changing background illumination was inferred from our own experience, whereas in the awake behaving animal, it was directly reported by the monkey. We found that the majority of V4 neurons shifted their color-tuning profile with each change in the background illumination: each time the color of the background on the computer screen was changed so as to simulate a change in illumination, cells shifted their color-tuning function in the direction of the chromaticity component that had been increased. A similar shift was also observed in colored match-to-sample psychometric functions of both human and monkey. The shift in monkey psychometric functions was quantitatively equivalent to the shift in the responses of the corresponding population of cells. We conclude that neurons in area V4 exhibit the property of color constancy and that their response properties are thus able to reflect color perception.
TGF-β1-Induced Long-Term Changes in Neuronal Excitability inAplysiaSensory Neurons Depend on MAPK
Authors: Chin Jeannie , Liu Rong-Yu , Cleary Leonard J. , Eskin Arnold , Byrne John H.
Published: April 2006

Transforming growth factor beta-1 (TGF-β1) plays important roles in the early development of the nervous system and has been implicated in neuronal plasticity in adult organisms. It induces long-term increases in sensory neuron excitability in Aplysia as well as a long-term enhancement of synaptic efficacy at sensorimotor synapses. In addition, TGF-β1 acutely regulates synapsin phosphorylation and reduces synaptic depression induced by low-frequency stimuli. Because of the critical role of MAPK in other forms of long-term plasticity in Aplysia, we examined the role of MAPK in TGF-β1-induced long-term changes in neuronal excitability. Prolonged (6 h) exposure to TGF-β1 induced long-term increases in excitability. We confirmed this finding and now report that exposure to TGF-β1 was sufficient to activate MAPK and increase nuclear levels of active MAPK. Moreover, TGF-β1 enhanced phosphorylation of the Aplysia transcriptional activator cAMP response element binding protein (CREB)1, a homologue to vertebrate CREB. Both the TGF-β1-induced long-term changes in neuronal excitability and the phosphorylation of CREB1 were blocked in the presence of an inhibitor of the MAPK cascade, confirming a role for MAPK in long-term modulation of sensory neuron function.
Dispute Settlement under the UN Convention on the Law of the Sea: Survey for 2004
Authors: Churchill Robin
Published: April 2006

This is the first of a projected series of annual surveys reviewing dispute settlement under the UN Convention on the Law of the Sea generally, rather than focusing purely on the International Tribunal for the Law of the Sea. The main developments during 2004 were the referral of two maritime boundary disputes in the Caribbean area to arbitration under Annex VII and a prompt release of vessel judgment by the ITLOS in the Juno Trader case.
The Slow Swim From Extinction: Saving Turtles in the South Pacific
Authors: Gillespie Alexander
Published: April 2006

The purpose of this paper is to set out the essential requirements for a successful regional agreement for sea turtles in the South Pacific. To achieve this, the current Regional Marine Turtle Conservation Programme (RMTCP) which runs under the auspice of the South Pacific Regional Environmental Programme (SPREP) will be juxtaposed against the "best practice" in this area, as evinced by current development in international environmental law and a number of other regional agreements which focus exclusively on sea turtles.
Submission of Brazil and Article 76 of The Law of the Sea Convention (LOSC) 1982
Authors: Egede Edwin
Published: April 2006

Brazil on 17 May 2004 became the second State to make its submission to the Commission on the Limits of the Continental Shelf (CLCS) as required by Article 76 of the Law of the Sea Convention (LOSC). The Brazilian submission assumes particular significance as the first submission to the CLCS by a developing State member of the Group of 77. This article seeks to examine the Brazilian submission vis-à-vis the provisions of Article 76 of LOSC.
Joint Development in the South China Sea: A New Approach
Authors: Keyuan Zou
Published: April 2006

The political situation in the South China Sea is complicated, as it contains potential for conflict with different national interests, in particular around the Spratly Islands which are currently under multiple territorial and maritime claims. This article argues for a new proposal of joint development, at least as a provisional means, pending the settlement of the territorial and maritime disputes, involving all the parties concerned, based on the 1982 United Nations Convention on the Law of the Sea and the 2002 Declaration on the Conduct of the Parties in the South China Sea Between the Association of Southeast Asian Nations (ASEAN) and China, so as to pave the way for the sharing of resources between ASEAN members and China on the one hand and to maintain regional peace and security in East Asia on the other.
Pivotal Advance: Eosinophil infiltration of solid tumors is an early and persistent inflammatory host response
Authors: Cormier Stephania A , Taranova Anna G , Bedient Carrie , Nguyen Thanh , Protheroe Cheryl , Pero Ralph , Dimina Dawn , Ochkur Sergei I , O’Neill Katie , Colbert Dana , Lombari Theresa R , Constant Stephanie , McGarry Michael P , Lee James J , Lee Nancy A
Published: April 2006

Tumor-associated eosinophilia has been observed in numerous human cancers and several tumor models in animals; however, the details surrounding this eosinophilia remain largely undefined and anecdotal. We used a B16-F10 melanoma cell injection model to demonstrate that eosinophil infiltration of tumors occurred from the earliest palpable stages with significant accumulations only in the necrotic and capsule regions. Furthermore, the presence of diffuse extracellular matrix staining for eosinophil major basic protein was restricted to the necrotic areas of tumors, indicating that eosinophil degranulation was limited to this region. Antibody-mediated depletion of CD4+ T cells and adoptive transfer of eosinophils suggested, respectively, that the accumulation of eosinophils is not associated with T helper cell type 2-dependent immune responses and that recruitment is a dynamic, ongoing process, occurring throughout tumor growth. Ex vivo migration studies have identified what appears to be a novel chemotactic factor(s) released by stressed/dying melanoma cells, suggesting that the accumulation of eosinophils in tumors occurs, in part, through a unique mechanism dependent on a signal(s) released from areas of necrosis. Collectively, these studies demonstrate that the infiltration of tumors by eosinophils is an early and persistent response that is spatial-restricted. It is more important that these data also show that the mechanism(s) that elicit this host response occur, independent of immune surveillance, suggesting that eosinophils are part of an early inflammatory reaction at the site of tumorigenesis.
The tissue pentraxin PTX3 limits C1q-mediated complement activation and phagocytosis of apoptotic cells by dendritic cells
Authors: Baruah Paramita , Dumitriu Ingrid E , Peri Giuseppe , Russo Vincenzo , Mantovani Alberto , Manfredi Angelo A , Rovere-Querini Patrizia
Published: April 2006

Pentraxins (PTX) and complement belong to the humoral arm of the innate immune system and have essential functions in immune defense to microbes and in scavenging cellular debris. The prototypic long PTX, PTX3, and the first component of the classical complement pathway, C1q, are innate opsonins involved in the disposal of dying cells by phagocytes. Whether the interaction between various innate opsonins impacts on their function is not fully understood. We show here that characterized Toll-like receptor (TLR) ligands elicit the production of C1q and PTX3 by immature dendritic cells (DC). Moreover, these molecules bind to dying cells with similar kinetics, although they recognize different domains on the cell membranes. PTX3 binds in the fluid phase to C1q, decreasing C1q deposition and subsequent complement activation on apoptotic cells. C1q increases the phagocytosis of apoptotic cells by DC and the release of interleukin-12 in the presence of TLR4 ligands and apoptotic cells; PTX3 inhibits both events. Moreover, PTX3 inhibited the cross-presentation of the MELAN-A/melanoma antigen-reactive T cell 1 (MART-1) tumor antigen expressed by dying cells, even in the presence of C1q. These results suggest that interaction of C1q and PTX3 influences the clearance of apoptotic cells by DC. The coordinated induction by primary, proinflammatory signals of C1q and PTX3 and their reciprocal regulation during inflammation influences the clearance of apoptotic cells by antigen-presenting cells and possibly plays a role in immune homeostasis.
TNF induces distinct gene expression programs in microvascular and macrovascular human endothelial cells
Authors: Viemann Dorothee , Goebeler Matthias , Schmid Sybille , Nordhues Ursula , Klimmek Kerstin , Sorg Clemens , Roth Johannes
Published: April 2006

The relevance of the diversity of endothelial cells (ECs) for the response to inflammatory stimuli is currently not well defined. Using oligonucleotide microarray technique, we systematically analyzed the tumor necrosis factor (TNF)-induced expression profile in human microvascular ECs (HMEC) and macrovascular human umbilical vein ECs (HUVEC), analyzing 13,000 human genes by microarray analysis. Using strict inclusion and exclusion criteria, microarray analysis revealed that about half of the TNF-induced genes were specific for HMEC-1 or HUVEC. The microarray data could widely be confirmed by quantitative reverse transcriptase-polymerase chain reaction and at the protein level. It is interesting that the majority of those genes regulated depending on the cell type encoded for chemokines, cytokines, and cell surface molecules. Our results argue for a more careful consideration of specific effects restricted to distinct subtypes of ECs. The establishment of EC type-specific expression patterns may thus provide the basis for a selective manipulation of specific endothelial subtypes in different inflammatory diseases.
C1q and MBL, components of the innate immune system, influence monocyte cytokine expression
Authors: Fraser Deborah A , Bohlson Suzanne S , Jasinskiene Nijole , Rawal Nenoo , Palmarini Gail , Ruiz Sol , Rochford Rosemary , Tenner Andrea J
Published: April 2006

It has recently been recognized that the innate immune response, the powerful first response to infection, has significant influence in determining the nature of the subsequent adaptive immune response. C1q, mannose-binding lectin (MBL), and other members of the defense collagen family of proteins are pattern recognition molecules, able to enhance the phagocytosis of pathogens, cellular debris, and apoptotic cells in vitro and in vivo. Humans deficient in C1q inevitably develop a lupus-like autoimmune disorder, and studies in C1q knockout mice demonstrate a deficiency in the clearance of apoptotic cells with a propensity for autoimmune responses. The data presented here show that under conditions in which phagocytosis is enhanced, C1q and MBL modulate cytokine production at the mRNA and protein levels. Specifically, these recognition molecules of the innate immune system contribute signals to human peripheral blood mononuclear cells, leading to the suppression of lipopolysaccharide-induced proinflammatory cytokines, interleukin (IL)-1α and IL-1β, and an increase in the secretion of cytokines IL-10, IL-1 receptor antagonist, monocyte chemoattractant protein-1, and IL-6. These data support the hypothesis that defense collagen-mediated suppression of a proinflammatory response may be an important step in the avoidance of autoimmunity during the clearance of apoptotic cells.
Literal salience in on-line processing of idiomatic expressions by second language learners
Authors: Cieślicka Anna
Published: April 2006

This article addresses the question of how second language (L2) learners understand idiomatic expressions in their second/foreign language and advances the proposition that literal meanings of idiom constituents enjoy processing priority over their figurative interpretations. This suggestion forms the core of the literal-salience resonant model of L2 idiom comprehension, whose major assumptions are outlined in the article. On the literal salience view, understanding L2 idioms entails an obligatory computation of the literal meanings of idiom constituent words, even if these idioms are embedded in a figurative context and if their idiomatic interpretation is well-known to L2 learners. The literal salience assumption was put to the test in a cross-modal lexical priming experiment with advanced Polish learners of English. The experiment showed more priming for visual targets related to literal meanings of idiom constituent words than for targets related figuratively to the metaphoric interpretation of the idiomatic phrase. This effect held true irrespective of whether the stimulus sentence contained a literal or a non-literal idiom.
Focus and split-intransitivity: the acquisition of word order alternations in non-native Spanish
Authors: Lozano Cristobal
Published: April 2006

Recent unrelated studies reveal what appears to be a common acquisitional pattern in second language acquisition (SLA). While some findings show that advanced learners can indeed achieve convergent, native-like competence with formal syntactic properties (even when these are underdetermined by the input), other findings suggest that they can display divergent and even optional competence at the syntax-discourse interface with discursive properties like focus and topic. These apparently contradictory observations are not coincidental, as they can also be traced in other acquisitional studies on L1 acquisition, L1 attrition in bilinguals, child SLA and SLI (specific language impairment).

If this pattern is correct, it should be observed in the L2 acquisition of any given property that is simultaneously governed by both a formal grammatical constraint and a discursive constraint. I tested whether this is the case in advanced non-native Spanish acquisition of the syntactic distribution of subject-verb (SV) and verb-subject (VS) word order, which is constrained by both a formal syntactic property (the Unaccusative Hypothesis or Split-intransitivity Hypothesis) and a property at the syntax-discourse interface (presentational focus).

Results show that the interlanguage grammars (ILGs) of both English ( n = 17) and Greek ( n = 18) learners of Spanish converge with the grammars of native Spanish speakers ( n = 14) when formal properties are involved, yet they diverge (in particular by showing optionality) with discursive focus. These results confirm the emerging view that acquisition of formal syntactic properties is more readily acquired than discourse properties, which are persistently problematic.
The acquisition of functional categories in early French second language grammars: the use of finite and non-finite verbs in negative contexts
Authors: Rule Sarah , Marsden Emma
Published: April 2006

This cross-sectional study of first language (L1) English adolescents learning French as a second language (L2) uses their development of negatives in relation to finite and non-finite verbs to investigate the status and nature of functional categories in these learners’ emerging grammars. Analysing oral data from elicited production tasks from instructed learners, it provides evidence for a lack of functional categories in the Initial State and the earliest L2 grammars (Vainikka and Young-Scholten, 1996; Hawkins, 2001). However, the results from the study also indicate that the functional category I (or T) then emerges reasonably rapidly. The pattern of development of negation and finite and non-finite verbs in these learners’ grammars also suggests that feature values are in place for the functional categories once they are projected, as learners consistently raise the verb. The learners do use root infinitives but the properties of these root infinitives differ to those found in L1 acquisition (Pierce, 1992; Wexler, 1994; 1998), thus supporting Wexler’s maturational account of Optional Infinitives in L1 acquisition. Additionally, the rare occurrence of raised non-finite verbs would indicate that there is a problem with the realization of surface morphology in accordance with the Missing Surface Inflection Hypothesis of Prévost and White (2000a) rather than an impairment in the grammar (Meisel, 1997; Hawkins, 2000).
On my mind: thoughts about salience, context and figurative language from a second language perspective
Authors: Kecskes Istvan
Published: April 2006

This article discusses three claims of the Graded Salience Hypothesis presented in Rachel Giora’s book On our mind. It is argued that these claims may give second language researchers the chance to revise the way they think about word meaning, the literal meaning-figurative meaning dichotomy and the role of context in language processing. Giora’s arguments are related to recent second language research and their relevance is explained through examples. There are also several suggestions made for further research.
Is there a role for airway clearance techniques in chronic obstructive pulmonary disease?
Authors: Hollandl Anne E , Buttonl Brenda M
Published: April 2006

Chronic cough and sputum production are common featuresof chronic obstructive pulmonary disease (COPD) and havea significant impact on exacerbation frequency and qualityof life. Despite this, techniques to assist with removal of sputum from the airway do not have a well-defined role in COPD management. Clinical trials of airway clearance techniques (ACTs) in COPD have shown mixed results with little evidence of long-term benefit. However many studies havefailed to account for the heterogeneity of COPD lung disease, particularly with regard to the presence of bronchiectasis. Analysis of short-term studies suggests that there may be a cohort of patients who will benefit from prescription of a sputum clearance regimen. This review proposes a physiological rationale for the use of ACTs in COPD, taking into consideration the presence of bronchiectasis, the amount of sputum produced, the degree of airflow obstruction and the presence of decreased lung elastic recoil. The selection of an optimal ACT for individuals with COPD should take into account its effects on lung vloumes, expiratory flow and dynamic airway compression. Care should be taken to avoid airway collapse during forced expirations in patients with reduced lung recoil pressure; positive expiratory pressure therapy or autogenic drainage may prove effective in this patient group. The acceptability of ACTs to patients should also be considered, especially where long-term adherence is required. Future research should focus on more appropriate matching of the physiological effects of individual ACTs to the pathophysiology of lung disease in COPD.
Psychometric properties of the TACQOL-asthma, a disease-specific measure of health related quality-of-life for children with asthma and their parents
Authors: Flapper B C.T. , Koopman H M , ten Napel C , van der Schans C P
Published: April 2006

The disease-specific-TACQOL-asthma questionnaire measures health-status and appraisal of health status. The TACQOL-asthma evaluates the personal feelings about problems in the domains, ‘complaints, situations, emotions, treatment and medication’. The TACQOL-asthma can be used alone or in combination with the generic TACQOL. Our objective was to study the psychometric properties of the TACQOL-asthma-questionnaire. Responses of 298 parents and children with asthma (age eight to 16 years) in four paediatric practices in the northern part of the Netherlands were studied. The factor-analysis and item-domain correlation analysis show a moderate to strong correlation between the different items and their hypothesised domains. For all items, the correlation of the separate item with the hypothesized domain is stronger than with any other domain. The internal consistency (Cronbach's alpha) of the domains is moderate to good. Concurrent correlation with the Paediatric-Asthma-Quality-of-Life-Questionnaire-(PAQLQ) was significant. Effect sizes of differences between asthma-severity classes in TACQOL-asthma and PAQLQ-scores were similar and of clinical importance. This study validates the TACQOL-asthma as a new disease-specific questionnaire. The TACQOL-asthma ensures a measurement of health status as well as appraisal ofhealth problems. The TACQOL-asthma has good reliability and validity properties to serve as an evaluative and discriminate disease-specifichealth-related-quality-of-life questionnaire.
A pilot study on a cognitive-behavioral asthma self-management program for adults
Authors: Tousman S , Zeitz H , Bristol C , Taylor L
Published: April 2006

The purpose of our research was to design, implement and evaluate a cognitive-behavioral asthma self-management program for adults. Seventeen adults with asthma completed an eight-week course (two hours, once a week) that consisted of interactive small group discussions and a behavior change procedure. The group discussions were led by a multi-disciplinary faculty (nurse, respiratory therapist, allergist, social worker, psychologist). Following each weekly discussion, participants would attempt to change a behavior related to the discussion. At the following meeting, participants would share their results and get feedback from the group; subsequently a new topic was introduced for discussion and a new behavioral change goal was added at the end of the meeting. Primary outcome measurements included asthma related quality of life, peak flow rate and frequency of key lifestyle behaviors. Outcome analyses indicated statistically significant improvements in frequency of: 1) peak flow monitoring; 2) practicing relaxation; 3) drinking 64 ounces of water a day (P < 0.05). Outcome analyses also indicated statistically significant improvements inquality-of-life (QOL) and asthma knowledge (P < 0.05). These results provide evidence that a cognitive-behavioral asthma education program that incorporates a behavior change procedure with interactive group discussions can lead to both knowledge acquisition and behavioral changes. Such outcomes are essential for reducing asthma morbidity and asthma mortality.
Ethical aspects of palliative care in lung cancer and end stage lung disease
Authors: Neerkin J , Riley J
Published: April 2006

Over 50 000 people die per year in England and Wales from lung cancer and chronic obstructive pulmonary disease (COPD). Current National Institute for Clinical Evidence guidelines for lung cancer and COPD recommend provision of palliative care for those that need it. Palliative care historically has accepted patients with cancer, but access to patients with non-malignant disease has been more sporadic. This paper aims to highlight the many ethical dilemmas faced when treating both these groups of patients. These include issues surrounding the form of treatment or treatment with drawal, the burden on the patient or on the health service; or conducting research in terminally ill patients.
Lung health in Japan
Authors: Nishimura K
Published: April 2006

Japan appears to be one of the healthiest nations. However, each step of healthcare services is not excellent while macroscopic outcomes are exceptional. Globalization is also key concept in Japanese respiratory healthcare services. As international communication between physicians become more common, the reality that various gaps in respiratory healthcare services still remain in place is becoming clearer. Now, clinicians are paying attention to global sources of information. Respiratory medicine will also change from experience-based medicine to evidence-based science.
Enantioselective Aerobic Epoxidation of Acyclic Simple Olefins Catalyzed by the Optically Active β-Ketoiminato Manganese(III) Complex
Authors: Nagata Takushi , Imagawa Kiyomi , Yamada Tohru , Mukaiyama Teruaki
Published: April 2006

Enantioselective aerobic epoxidation of acyclic cis-olefins into the corresponding optically active epoxides was carried out with good-to-high enantioselectivities by using a new class of optically active β-ketoiminato manganese(III) complex catalyst, N,N′-ethylenebis(α-mesitoyl-β-ketoiminato)manganese(III) chloride. The key intermediate of the present epoxidation is also discussed.
Sugar-Assisted Chirality Control of Tris(2,2′-bipyridine)-Metal Complexes
Authors: Nakashima Kazuaki , Shinkai Seiji
Published: April 2006

2,2′-Bipyridine-4,4′-diboronic acid (2), a 2,2′-bipyridine derivative with sugar-binding sites was synthesized. The Δ vs. Λ chirality of the Fe2+·23 complex was selectively generated in correlation with the absolute configuration of added saccharides.
Ring Hydroxylations of Aromatic Amino Acid Derivatives and Toluene by Hydrogen Peroxide Catalyzed by Manganese Halogenated Porphyrins in CH2Cl2/H2O and Lipid Bilayers
Authors: Iida Kouji , Nango Mamoru , Okada Kenichi , Matsumoto Shunichi , Matsuura Mitsutaka , Yamashita Keiji , Tsuda Kazuichi , Kurono Yukihisa , Kimura Yoshikazu
Published: April 2006

Manganese fluorinated porphyrins catalyzed the ring hydroxylation of phenylalanine derivatives and toluene with H2O2 and an enhanced hydroxylation was observed especially in phospholipid bilayers when imidazole was present. The hydroxylation depended upon the structures of porphyrins and substrates.
Crystal-Chemical Factors Responsible for the Distribution of Octahedral Cations Over trans- and cis-Sites in Dioctahedral 2:1 Layer Silicates
Authors: Drits Victor A. , McCarty Douglas K. , Zviagina Bella B.
Published: April 2006

Crystal chemical analysis of various dioctahedral 2:1 phyllosilicates consisting of trans-vacant (tv) and cis-vacant (cv) layers and interstratified cv and tv layers shows that there is compositional control over the distribution of octahedral cations over trans and cis sites. Fe3+ and Mg-rich dioctahedral micas (celadonite, glauconite, leucophyllite and most phengite) occur only as tv varieties. Similarly, the occurrence of tv illites and tv illite fundamental particles in illite-smectite (I-S) does not depend significantly on the cation composition of the 2:1 layers. In contrast, compositional restrictions exist to control the occurrence of pure cv1M illite, which can form only as Fe- and Mg-poor varieties. Similarly, proportions of cv and tv layers in illite fundamental particles depend on the amount of Al in octahedral and tetrahedral sheets of the 2:1 layers.

Simulations of atomic coordinates and interatomic distances for periodic tv1M and cv1M illite structures allow us to reveal the main structural factors that favor the formation of cv layers in illite and I-S. It is shown that in contrast to the tv1M structure, interlayer K in cv1M illite has an environment which is similar to that in 2M1 muscovite. This similarity along with a high octahedral and tetrahedral Al content probably provides stability for cv1M illite in low-temperature natural environments. Because of structural control, the occurrence of monomineral cv1M illite, its association with tv 1M illite, and interstratified cv-tv illite fundamental particles is confined by certain physical and chemical conditions. These varieties are most often formed by hydrothermal activity of different origin. The initial material for their formation should be Al-rich and the hydrothermal fluids should be Mg- and Fe-poor. They occur mostly around ore deposits, in bentonites and in sandstone sedimentary rocks.

The factors governing the formation of tv and cv layers in dioctahedral smectite are probably related to the layer composition and local order-disorder in the distribution of isomorphous octahedral cations, because there is no influence from fixed interlayer cations. In particular, the occurrence of Mg-OH-Mg cation arrangements is more favorable for the formation of cv montmorillonite layers.
Nickel Solubility and Precipitation in Soils: A Thermodynamic Study
Authors: Peltier Edward , Allada Ramakumar , Navrotsky Alexandra , Sparks Donald L.
Published: April 2006

The formation of mixed-metal-Al layered double hydroxide (LDH) phases similar to hydrotalcite has been identified as a significant mechanism for immobilization of trace metals in some environmental systems. These precipitate phases become increasingly stable as they age, and their formation may therefore be an important pathway for sequestration of toxic metals in contaminated soils. However, the lack of thermodynamic data for LDH phases makes it difficult to model their behavior in natural systems. In this work, enthalpies of formation for Ni LDH phases with nitrate and sulfate interlayers were determined and compared to recently published data on carbonate interlayer LDHs. Differences in the identity of the anion interlayer resulted in substantial changes in the enthalpies of formation of the LDH phases, in the order of increasing enthalpy carbonate<sulfate<nitrate. Substitution of silica for carbonate resulted in an even more exothermic enthalpy of formation, confirming that silica substitution increases the stability of LDH precipitates. Both mechanical mixture and solid-solution models could be used to predict the thermodynamic properties of the LDH phases. Modeling results based on these thermodynamic data indicated that the formation of LDH phases on soil mineral substrates decreased Ni solubility compared to Ni(OH)2 over pH 5–9 when soluble Al is present in the soil substrate. Over time, both of these precipitate phases will transform to more stable Ni phyllosilicates.
Heating Fe Oxide-Rich Soils Increases the Dissolution Rate of Metals
Authors: Perrier Nicolas , Gilkes Robert J. , Colin Fabrice
Published: April 2006

Evidence for fire affecting the solubility of metals in Fe oxide-rich Oxisols of the Koniambo Massif of New Caledonia is presented. Acid-dissolution studies showed that Ni, Al and Cr are substituted for Fe in the structure of the Fe oxides. Thermal dehydroxylation of goethite under oxidizing conditions led to the formation of hematite and to the migration of some of these metals towards the surface of hematite crystals as indicated by their enhanced release during the early stage of dissolution. Dehydroxylation of goethite under reducing conditions led to the formation of hematite and maghemite. Nickel and Al were released preferentially during the early stages of dissolution whereas Cr was not released preferentially and may be uniformly incorporated within maghemite and hematite crystals. These results have significance to the mineral-processing industry, to geochemical exploration and to the availability of these metals to plants growing on burnt soils.
Thermal and Mineral Properties of Al-, Cr-, Mn-, Ni- and Ti-Substituted Goethite
Authors: Wells M. A. , Fitzpatrick R. W. , Gilkes R. J.
Published: April 2006

Mineralogical and thermal characteristics of synthetic Al-, Cr-, Mn-, Ni- and Ti-bearing goethites, synthesized via alkaline hydrolysis of metal-ferrihydrite gels, were investigated by powder X-ray diffraction and differential thermal analysis. Shifts in unit-cell dimensions were consistent with size of substituent metal ions and confirmed the incorporation of Al3+, Cr3+, Mn3+, Ni2+ and Ti4+ in the goethite structure. A weight loss of 6.2 wt.% for goethite containing 12.2 mol.% Ti, being significantly less than for stoichiometric goethite, is consistent with the replacement of Fe by Ti in the goethite structure coupled with the substitution of O2− ions for OH− (i.e. proton loss). These data provide the first confirmation of the direct replacement of Fe by Ti within goethite. Formation of multiple dehydroxylation endotherms for goethite containing 4.5 mol.% Al, 15.3 mol.% Mn and 12.2 mol.% Ti was not attributed to the decomposition of surface OH groups or related simply to the crystallinity of precursor goethite (‘high-a’ vs. ‘low-a’) as defined by the magnitude of a. Instead, endotherm doublet formation was associated with weight loss due to the dehydroxylation of goethite remaining after initial phase transformation to protohematite and to the evolution of OH− associated with the rapid increase in crystallite size of protohematite directed primarily along the a direction. Development of the first endotherm is due to initial dehydroxylation and transformation to protohematite. With continued heating of well ordered goethite or goethite containing moderate to high levels of substituent cations, domain growth along the a direction is delayed or inhibited to a critical point that provides enough thermal energy to enable goethite transformation to proceed to completion and for proto-hematite domain growth to occur. This results in the formation of a second endotherm. For less well ordered goethite and/or goethite containing only low levels of foreign metal cations, protohematite domain growth is not inhibited and proceeds continuously with heating to give only a single endotherm.
Comparisons of Structural Fe Reduction in Smectites by Bacteria and Dithionite: An Infrared Spectroscopic Study
Authors: Lee Kangwon , Kostka Joel E. , Stucki Joseph W.
Published: April 2006

The reduction of structural Fe in smectite is mediated either abiotically, by reaction with dithionite, or biotically, by Fe-reducing bacteria. The effects of abiotic reduction on clay-surface chemistry are much better known than the effects of biotic reduction. Since bacteria are probably the principal agent for mediating redox processes in natural soils and sediments, further study is needed to ascertain the differences between biotic and abiotic reduction processes. The purpose of the present study was to compare the effects of dithionite (abiotic) and bacteria (biotic) reduction of structural Fe in smectites on the clay structure as observed by infrared spectroscopy. Three reference smectites, namely, Garfield nontronite, ferruginous smectite (SWa-1), and Upton, Wyoming, montmorillonite, were reduced to similar levels by either Shewanella oneidensis or by pH-buffered sodium dithionite. Each sample was then analyzed by Fourier transform infrared spectroscopy (FTIR). Parallel samples were reoxidized by bubbling O2 gas through the reduced suspension at room temperature prior to FTIR analysis. Redox states were quantified by chemical analysis, using 1, 10-phenanthroline. The reduction level achieved by dithionite was controlled to approximate that of the bacterial reduction treatment so that valid comparisons could be made between the two treatments. Bacterial reduction was achieved by incubating the Na-saturated smectites with S. oneidensis strain MR-1 in a minimal medium including 20 mM lactate. After redox treatment, the clay was washed four times with deoxygenated 5 mM NaCl. The sample was then prepared either as a self-supporting film for OH-stretching and deformation bands or as a deposit on ZnSe windows for Si-O stretching bands and placed inside a controlled atmosphere cell also fitted with ZnSe windows. The spectra from bacteria-treated samples were compared with dithionite-treated samples having a similar Fe(II) content. The changes observed in all three spectral regions (OH stretching, M2-O-H deformation, and Si-O stretching) for bacteria-reduced smectite were similar to results obtained at a comparable level of reduction by dithionite. In general, the shift of the structural OH vibration and the Si-O vibration, and the loss of intensity of OH groups, indicate that the bonding and/or symmetry properties in the octahedral and tetrahedral sheets changes as Fe(III) reduces to Fe(II). Upon reoxidation, peak positions and intensities of the reduced smectites were largely restored to the unaltered condition with some minor exceptions. These observations are interpreted to mean that bacterial reduction of Fe modifies the crystal structures of Fe-bearing smectites, but the overall effects are modest and of about the same extent as dithionite at similar levels of reduction. No extensive changes in clay structure were observed under conditions present in our model system.
Identification of Neoformed Ni-Phyllosilicates Upon Ni Uptake in Montmorillonite: A transmission Electron Microscopy and Extended X-ray Absorption Fine Structure Study
Authors: Dähn Rainer , Jullien Michel , Scheidegger André M. , Poinssot Christophe , Baeyens Bart , Bradbury Michael H.
Published: April 2006

The aim of this work was to investigate whether neoformed Ni-phyllosilicates can be observed and identified using transmission electron microscopy (TEM) in combination with energy dispersive spectroscopy (EDS). The investigations focused on Ni-phyllosilicates formed from Ni-doped montmorillonite. The reaction conditions (pH 8, [Ni]initial = 660 and 3300 µM, 0.2 M Ca(NO3)2) employed were similar to those used in previous polarized extended X-ray absorption fine structure (P-EXAFS) investigations of neoformed Ni-phyllosilicates in a Ni-montmorillonite system.

The TEM investigations of Ni-doped montmorillonite revealed the presence of small, thin particles consisting of coherent stacks that yielded only three to five lattice fringes with spacings consistent with smectites. These small particles were neoformed phyllosilicates, based on the fact that the small particles were only observed in Ni-doped samples and their Ni content, as determined from EDS analysis, was high (up to 10 wt.% NiO). Furthermore, the particles did not possess the characteristic properties of montmorillonite particles, such as a 2:1 Si to Al ratio; instead these particles were rich in Si (up to 75 wt.% SiO2). Unlike montmorillonite, these particles did not contain any Fe. The particles were also significantly more resistant to electron beam damage than montmorillonite particles, and EXAFS measurements confirmed the presence of neoformed Ni-phyllosilicates.

The TEM study further indicates the presence of a variety of additional minerals (e.g. cristobalite, halloysite) and an X-ray amorphous Si-rich phase. A Ni signal could only be detected in the latter phase at high Ni loadings (403 µmol/g), suggesting that Ni uptake at low metal loadings (<90 µmol/g) is mainly controlled by the neoformation of phyllosilicates.
Effect of Acid Treatment and Alkali Treatment on Nanopore Properties of Selected Minerals
Authors: Jozefaciuk Grzegorz , Matyka-Sarzynska Dorota
Published: April 2006

Bentonite, biotite, illite, kaolin, muscovite, vermiculite and zeolite were acidified or alkalized with HCl orNaOH of concentrations 0.0, 0.1, 1.0 and 5.0 mole dm−3 at room temperature for 2 weeks and converted into Ca homoionic forms. Low-temperature nitrogen and room-temperature water-vapor adsorption-desorption isotherms were used to characterize the mineral pores of radii between 1 and 30 nm. Nanopore volumes, size distributions, average radii and fractal dimensions were calculated. Values calculated from the nitrogen isotherms differed from those derived from water-vapor data. With an increase of the acid-treatment concentration, the pore volumes measured using both adsorption techniques increased markedly for all minerals. The pore radii measured from nitrogen isotherms appeared to decrease for all minerals except zeolite, while the pore radius calculated from water-vapor data increased in most cases. The fractal dimension measured from water vapor isotherms decreased in all cases indicating smoothing of the mineral surfaces and decrease in pore complexity. No well defined trends in any of the pore parameters listed above were noted under alkaline treatment. In the reaction of each mineral with acid and alkali treatments, the individual character of the mineral and the presence of impurities seems important.
The Effect of Pressure on Order/Disorder in Kaolinite Under Wet and Dry Conditions
Authors: Galán Emilio , Aparicio Patricia , La Iglesia Ángel , González Isabel
Published: April 2006

Well ordered kaolinite was isostatically and uniaxially pressurized up to 13,200 kg/cm2 for 10 min in dry conditions and the effects of pressure on kaolinite order were determined by analyzing the shapes of two-dimensional diffraction bands on X-ray powder diffraction patterns. Increased pressure decreased the percentage of low-defect kaolinite phase, and isostatic pressure proved to be more effective than uniaxial pressure in increasing disorder, e.g. the degree of disorder resulting from 2000 kg/cm2 isostatic pressure was equivalent to that caused by a 3200 kg/cm2 uniaxial pressure. Also, the effect of high pressure was similar to that obtained with lower pressures applied several times (e.g. the effect of applying 8500 kg/cm2 pressure for 10 min was comparable to using 3200 kg/cm2 pressure five times).

In addition, six kaolinites of different structural order were isostatically pressurized up to 4000 kg/cm2 for 10 min, both in dry and wet (water) conditions. Under dry conditions, changes in structurally ordered kaolinite were comparable to those cited above whereas kaolinite pressurized in wet conditions showed a moderate improvement in structural order.

These results may contribute to our understanding of kaolinite behavior during burial diagenesis and low-grade metamorphism. In addition, these results can also be used in industry to improve kaolin technological properties that depend on kaolinite structural order by application of appropriate industrial pressure processes.
Low-Temperature Hydrothermal Alteration of Silicic Glass at the PACMANUS Hydrothermal Vent Field, Manus Basin: An XRD, SEM and AEM-TEM study
Authors: Glorgetti Glovanna , Monecke Thomas , Kleeberg Reinhard , Hannington Mark D.
Published: April 2006

Dacitic lava recovered from the immediate subsurface of the submarine PACMANUS hydrothermal vent field exhibits variable degrees of hydrothermal alteration resulting from the interaction of the glassy volcanic rocks with mineralizing hydrothermal fluids at relatively low temperatures. Transmission electron microscopic (TEM) investigations revealed that the felsic volcanic glass transformed to nm-thick smectitic flakes of the montmorillonite-beidellite series via a dissolution and reprecipitation mechanism. The process of smectite formation did not proceed through X-ray amorphous or poorly crystalline transitional phases. Alteration of the glass was found to be most pronounced adjacent to perlitic cracks and vesicles that form an interconnected network focusing fluid flow. Glass dissolution adjacent to these fluid pathways resulted in a characteristic alteration texture at the nm scale; the intensely altered groundmass contains round cavities that are partially coated or filled by smectitic flakes. The Mg content of the smectite broadly increases towards the fluid pathways. Smectitic flakes with compositions corresponding to saponite occur in the intensely altered groundmass adjacent to perlitic cracks. In addition, anatase, apatite and rare kaolinite were formed during the alteration of the volcanic glass. Primary minerals including plagioclase show only minor textural evidence of alteration. However, some primary plagioclase laths show X-ray amorphous rims depleted in Na, Ca and Al. The TEM investigations of the dacitic lava samples from the PACMANUS vent field demonstrate that volcanic glass has a higher susceptibility to hydrothermal alteration at low temperatures than most associated primary phases. The findings of the study suggest that the interaction between the volcanic rock and the hydrothermal fluids proceeded under open-system conditions leading to a mobilization of alkali elements and a redistribution of Ti at the nm scale. The Mg required for the formation of trioctahedral smectite was supplied by the hydrothermal fluids.
Structural Investigations of Natural and Synthetic Chlorite Minerals by X-ray Diffraction, Mössbauer Spectroscopy and Solid-State Nuclear Magnetic Resonance
Authors: Zazzi Åsa , Hirsch Tomas K. , Leonova Ekaterina , Kaikkonen Andrei , Grins Jekabs , Annersten Hans , Edén Mattias
Published: April 2006

The structures of one synthetic and two natural chlorites of the chlinochlore type were explored using X-ray diffraction, magic-angle spinning nuclear magnetic resonance (NMR) and Mössbauer spectroscopy. Rietveld refinements indicated that all structures are of the trioctahedral ordered IIb polytype. Mössbauer spectra provided the ratio IIFe/IIIFe but gave no evidence for the presence of IIIFe in the brucite-like sheet. We also report unit-cell parameters, Mössbauer isomeric shifts, Si NMR chemical shifts as well as 27Al isotropic shifts and quadrupolar coupling parameters. Very broad 29Si NMR peaks from the natural samples prevented us from obtaining accurate information on the Si-Al ordering in the tetrahedral sheets; the limitations of 29Si NMR as applied to natural chlorites are discussed. High-resolution 3QMAS NMR resolved the 27Al signal of the M4 octahedral site in the brucite-like sheet from the other three Al signals of crystallographically inequivalent octahedral positions.
Detecting Chlorite in the Chinese Loess Sequence by Diffuse Reflectance Spectroscopy
Authors: Ji Junfeng , Zhao Liang , Balsam William , Chen Jun , Wu Tao , Liu Lianwen
Published: April 2006

Chlorite is one of the most common Fe-bearing minerals and is susceptible to weathering in loess and soils. The conventional method for analyzing chlorite, based on XRD with the Rietveld technique, is quantitative, but very time consuming and expensive. In this paper we develop a new methodology based on diffuse reflectance spectroscopy (DRS) and selective chemical extractions to identify chlorite qualitatively in the Chinese loess sequence and present evidence suggesting that DRS may be used to quantify chlorite content. The spectral signature of chlorite in loess is obscured by Fe oxides, but becomes obvious when they are removed. Changes in the ferrous absorption band near 1140 nm vary consistently with changing chlorite content. Using this spectral feature, DRS can distinguish chlorite contents as small as 1 wt.% in loess sediments. Future possibilities for this method in other soil and sediment types need to be explored.
Tibetan Folk Opera: Lhamo in Contemporary Cultural Politics
Authors: Ahameda Saiyada Jamila
Published: April 2006

Lhamo, the popular folk opera of Tibet is a genre in which the contested politics of the Tibetan diaspora and the People's Republic of China are displayed. This essay notes the practice of the art by the Tibetan refugee community in India and beyond, where it evokes nostalgia for a lost existence and the struggle for a return to the Tibetan Buddhist homeland. Meanwhile the art has been redeveloped in the People's Republic of China in the wake of the Cultural Revolution and used to support Chinese claims to Tibet. Lhamo presents a case study of a particular art and how it can be articulated to different political and economic ends.