bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ionic liquids-kaolinite nanostructured materials. Intercalation of pyrrolidinium salts
Authors: Letaief Sadok , Detellier Christian 
Published: March 2008

AbstractIonic liquids intercalated in kaolinite constitute a novel class of nanostructured material. Kaolinite-pyrrolidinium halide intercalates have been prepared successfully by reacting the pyrrolidinium salts with kaolinite which was preintercalated with dimethyl sulfoxide (DMSO) using the melt condition under N2. X-ray diffraction, 13C magic angle spinning nuclear magnetic resonance, differential thermal analysis (DTA)-thermal gravimetric analysis, and Fourier transform infrared spectroscopy confirm the displacement of DMSO during the intercalation process. Based on results from the various characterization techniques, a structural model is proposed in which one mole of the pyrrolidinium salt covers two or three structural units of kaolinite, depending on the structure and size of the salt. The thermal stability was improved remarkably after intercalation of the pyrrolidinium salts, compared to the pre-intercalate. The DTA-TGA data show that the largest number of organic units released and decomposed, occurs under N2 flow, at temperatures ranging from 260 to 340°C, depending on the nature of the intercalated organic salts.
NMR spectroscopy of naturally occurring surface-adsorbed fluoride on Georgia kaolinite
Authors: Cochiara Stacey G. , Phillips Brian L. 
Published: March 2008

AbstractUsing 19F magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy, we show that most of the fluoride present in the KGa-lb reference kaolinite from Washington County, Georgia, occurs as a surface-adsorbed species bonded to Al. This surface fluoride can be removed from the <2 µm fraction by acid wash, but is largely retained in the coarse fraction. Correlation of integrated 19F NMR peak intensities with fluoride sorption experiments indicates a bulk F content of ∼144 ppm for KGa-1b, of which ∼30% substitutes for hydroxyl sites in the mineral structure and the remaining 70% occurs adsorbed on particle surfaces, corresponding to an edge surface fluoride density of ∼0.7 F− nm−2. 19F{27Al} TRAPDOR (TRAnsfer of Populations in DOuble Resonance) NMR data for the original kaolinite and for products of F− sorption experiments at pH 4 show that all of the observed 19F signals arise from fluoride bonded to Al atoms. Furthermore, bridging Al-F-Al sites and terminal Al-F give distinctly different TRAPDOR fractions allowing assignment of resolved peaks based on the number of Al in the first coordination sphere. This result was confirmed for fluoride adsorbed to the surface of gibbsite from aqueous suspension. No evidence was found for Si-F-type environments on the kaolinite surfaces.
Diagenetic reorientation of phyllosilicate minerals in Paleogene mudstones of the Podhale Basin, southern Poland
Authors: Day-Stirrat Ruarri J. , Aplin Andrew C. , Środoń Jan , van der Pluijm Ben A. 
Published: March 2008

AbstractWe used high-resolution X-ray texture goniometry to quantify changes in the mm-scale orientation of phyllosilicate minerals in a suite of Paleogene mudstones from the Podhale Basin in southern Poland. The sample set covers an estimated range of burial depths between 2.4 and 7.0 km, corresponding to a temperature range of 60–160°C. Although mechanical compaction has reduced porosities to ∼10% in the shallowest samples, the phyllosilicate fabric is only modestly aligned. Coarser-grained (>10 µm) detrital chlorite and mica appear to be more strongly aligned with (001) parallel to bedding, suggesting their deposition as single grains rather than as isotropic flocs or aggregates. From 2.4 to 4.6 km, R0 illite-smectite with 40–50% illite layers changes to R1 illite-smectite with 70–80%) illite layers. At the same time kaolinite is lost and diagenetic chlorite is formed. The mineralogical changes are accompanied by a strong increase in the alignment of illite-smectite, chlorite, and detrital illite, parallel to bedding and normal to the presumed principal effective stress. We propose that the development of a more aligned I-S fabric results from the dissolution of smectite and the growth of illite with (001) normal to the maximum effective stress. Water released by illitization may act as a lubricant for the rotation of all platy minerals into nanoporosity transiently formed by the illitization reaction. At greater depths and temperatures, further illitization is inhibited through the exhaustion of K-feldspar. After the cessation of illitization, a further 2.4 km of burial only results in a small increase in phyllosilicate alignment. At such small values for porosity and pore size, increasing stress does not substantially reorient phyllosilicates in the absence of mineralogical change.
Dendritic cell subtypes as primary targets of vaccines: the emerging role and cross-talk of pattern recognition receptors
Authors: Benkő Szilvia , Magyarics Zoltán , Szabó Attila , Rajnavölgyi Éva 
Published: March 2008

AbstractPreventive vaccination is the most successful approach against infectious diseases and has a great impact on world health. Vaccines operate through the activation of innate immunity that helps to stimulate antigen-specific T- and B-lymphocytes. These events are orchestrated by dendritic cells (DCs) that are able to sample foreign structures and concomitantly sense ‘danger signals’. Thus, DCs provide a functional link between innate and acquired immunity, and due to their regulatory potential are referred to as natural adjuvants. Human conventional and plasmacytoid DCs express different sets of well-characterized Toll-like membrane receptors (TLRs) that recognize a broad range of conserved molecular patterns of pathogens. The recently discovered cytosolic Nod-like receptors (NLRs) and RIG-like helicases (RLHs) also turned out to participate in pathogen recognition and modulation of immune responses through interacting signaling pathways. As a result of their collaboration, the TLR, NLR and RLH recognition systems induce the secretion of different combinations of cytokines that play a fundamental role in T-cell activation and instruction. Ligands of the innate recognition systems emerge as new adjuvants for vaccine design, whereas manipulation of the signaling pathways mediated by these receptors offers new avenues for fine tuning immune responses and optimizing immunotherapies.
Modeling of variant copies of subunit D1 in the structure of photosystem II from Thermosynechococcus elongatus
Authors: Loll Bernhard , Broser Matthias , Kós Peter B. , Kern Jan , Biesiadka Jacek , Vass Imre , Saenger Wolfram , Zouni Athina 
Published: March 2008

Abstract
In the cyanobacterium Thermosynechococcus elongatus BP-1, living in hot springs, the light environment directly regulates expression of genes that encode key components of the photosynthetic multi-subunit protein-pigment complex photosystem II (PSII). Light is not only essential as an energy source to power photosynthesis, but leads to formation of aggressive radicals which induce severe damage of protein subunits and organic cofactors. Photosynthetic organisms develop several protection mechanisms against this photo-damage, such as the differential expression of genes coding for the reaction center subunit D1 in PSII. Testing the expression of the three different genes (psbAI, psbAII, psbAIII) coding for D1 in T. elongatus under culture conditions used for preparing the material used in crystallization of PSII showed that under these conditions only subunit PsbA1 is present. However, exposure to high-light intensity induced partial replacement of PsbA1 with PsbA3. Modeling of the variant amino acids of the three different D1 copies in the 3.0 Å resolution crystal structure of PSII revealed that most of them are in the direct vicinity to redox-active cofactors of the electron transfer chain. Possible structural and mechanistic consequences for electron transfer are discussed.
Analysis of the human cytomegalovirus pp65-directed T-cell response in healthy HLA-A2-positive individuals
Authors: Schalich Juliane , Vytvytska Oresta , Zauner Wolfgang , Fischer Michael B. , Buschle Michael , Aichinger Gerald , Klade Christoph S. 
Published: March 2008

AbstractHuman cytomegalovirus (HCMV) is contained by T-lymphocyte responses focused towards the major tegument protein pp65. To systematically identify T-cell epitopes, we applied the following strategy: 441 overlapping 15mer peptides spanning the entire HCMV pp65 antigen in 1-aa steps were screened in enzyme-linked immunospot (ELIspot) assays for interferon gamma (IFN-γ) secretion by peripheral blood mononuclear cells (PBMCs) from nine healthy HCMV-seropositive subjects expressing human leukocyte antigen (HLA)-A2. This analysis confirmed a number of previously known epitopes and revealed several new ones. A total of 26 epitopes were identified, including 14 HLA-A2, four HLA-B7, -B35, -B12 and -B44 restricted class I epitopes, six class II epitopes, and two epitopes of unknown restriction. Three novel HLA-A2 epitopes were confirmed using T2-cells, and one peptide for which only binding data had been published so far was verified. Two novel class II epitopes were confirmed by intracellular cytokine staining. Responses were usually oligoclonal against up to seven HLA-A2 epitopes, albeit with a few dominating epitopes. Clusters of overlapping epitopes (hot-spots) were identified. These and the newly identified T-cell epitopes may be of great value for epitope-based immunotherapeutic approaches, including peptide vaccines.
Maintenance of serological memory
Authors: Wrammert Jens , Ahmed Rafi 
Published: March 2008

AbstractLong-lived plasma cells are key to maintaining long-term humoral immunity after infection or vaccination. Some vaccines and/or infections induce antibody levels that remain stable for the life of the individual. However, the mechanism whereby these long-lived plasma cells are maintained over long periods of time remains an open question. Furthermore, given a finite number of sustainable plasma cells within the bone marrow, it is also unclear how space for newly induced plasma cells is generated without compromising the pre-existing repertoire. Here we review the current understanding of these important issues.
Crystallographic aspects of the linear electro-optic effect
Authors: Bohatý Ladislav 
Published: March 2008

Aspects of symmetry and crystal chemistry of the linear electrooptic effect are analyzed on the basis of new experimental results.
Relations between the linear electro-optic effect [r
σ
ijk] (unclamped) and the linear electrostrictive effect [d
ijk] are investigated by comparison of the longitudinal effects r'111 and d'111; The relation |d'111|max/|r'111|max≥1 is valid for 41 of the hitherto available data of 49 crystals.
Guidelines for the search of crystals with high electro-optic effects are reviewed. The most important keywords for a “chemical engineering” of new electro-optic materials are: pyroelectric symmetry groups; “polar” structural units; structures with strongly asymmetric bonds; molecules with high hyperpolarizabilities; structures tending towards a dielectric instability.
Stream Gradient‐Related Movement and Growth of Atlantic Salmon Parr during Winter
Authors: Stickler Morten , Enders Eva C. , Pennell Curtis J. , Cote David , Alfredsen Knut , Scruton David A. 
Published: March 2008

AbstractThere has been considerable focus on winter studies of Atlantic salmonSalmo salarparr during the last two decades. However, a lack of knowledge exists about the linkage between the physical conditions, including ice, and parr behavior in flow environments during the cold season. In this study, the movement and growth of Atlantic salmon parr were studied during winter in two stream sections with different gradients (0.3% and 1.8%) in a small natural river. Passive integrated transponder (PIT) technology was implemented by using both fixed antennae and mobile tracking devices. In the low‐gradient section, the formation of surface ice dominated and created stable conditions, whereas in the high‐gradient section, the formation of anchor ice and anchor ice dams occurred periodically and produced a dynamic environment. The results indicated a relationship between parr movement and river gradient. Movement by parr was negatively correlated with time from autumn to late winter but increased as spring approached. The level of movement was considered low (median = 0.9 m), but larger movements (up to 125.6 m) were recorded, indicating individual variation. Furthermore, parr inhabiting the low‐gradient section with the static ice formation exhibited larger movement than parr in the high‐gradient section with dynamic ice formation. Parr showed high site fidelity to both high‐ and low‐gradient sections but were less attracted to pool habitats. Finally, from late autumn to spring, parr demonstrated a specific growth rate close to 0.0%, indicating suitable conditions in both sections. As this study implies, the complexity of physical conditions during winter may lead to variability in individual fish response (i.e., movements). However, the results also imply that winter is not a limiting factor in parr performance if fish have access to suitable cover, such as areas with low substrate embeddedness.
Instability of Retroviral DNA Methylation in Embryonic Stem Cells
Authors: Minoguchi Shigeru , Iba Hideo 
Published: March 2008

Abstract
The epigenetic status of pluripotent stem cells has been demonstrated to be extremely unstable. In our current study, we have attempted to further investigate the epigenetic dynamics of the stem cell genome by monitoring the expression of the murine stem cell virus (MSCV) retroviral vector in embryonic stem (ES) cells. Although MSCV is progressively silenced by proviral DNA methylation in ES cells, a substantial number of MSCV-transduced ES cell clones do show variegated proviral expression. This expression profile is due in part to the transient and reversible properties of MSCV silencing. However, the spontaneous reactivation rates of the silenced proviruses differ significantly between these variegated clones, indicating that the reversibility of silencing is dependent on the proviral integration site. Our current data suggest that the fidelity of DNA methylation among the genomic sequences that flank the proviral integration sites may be the determinant of this reversibility of MSCV silencing. Given that the adjoining epigenome environment affects the epigenetic regulation of proviral DNA, the reversible MSCV silencing effect is thus likely to reflect a unique and interesting feature of ES cell epigenome regulation that has not previously been revealed.
Disclosure of potential conflicts of interest is found at the end of this article.
Limitations of the current practices used to perform ecological risk assessment
Authors: Kapustka Larry 
Published: March 2008

Abstract
The framework for ecological risk assessments has provided a way to analyze stressors in the environment. Despite the power of this tool to inform environmental management decisions, the practice has not reached its full potential. In this paper, limitations of the practice are described under 2 categories, namely inherent and contrived. Inherent limitations are constraints of nature that we need to be aware of as we design and interpret studies. Contrived limitations are impediments that have arisen in the practice through precedent or policy. The closing portion of this paper provides a series of short-term and long-term steps that could remove some of the limitations, especially the contrived ones, and improve the usefulness of risk assessments.
Validity of the interview on pets kept at home for predicting the actual domestic expsoure to their specific allergens. Krakow inner city area study
Authors: Jedrychowski Wieslaw , Perera Frederica , Maugeri Umberto , Zembala Marek , Hajto Barbara , Flak Elzbieta , Mroz Elzbieta , Sowa Agata 
Published: March 2008

AbstractThe aim of the study was to describe the exposure to dog (Can f 1) and cat (Fel d 1) allergens within homes of very young children living with and without pets, and to assess the validity of the interview on pets for predicting the actual exposure to pet allergens in house dust. House dust samples were collected in 275 dwellings from the mattresses, children’s bedroom and kitchen floors. In the laboratory, dust samples were analyzed for Can f 1 and Fel d 1 using monoclonal antibody enzyme-linked immunosorbent assays (ELISA). The majority of households (79.3%) had neither a dog nor a cat living in the home over the past 6 months preceding the survey. Dog allergen above 2 μg/g dust were found in 22.5% of homes and 14.2% of homes contained dog allergen above 10 μg/g of house dust. In the total study sample, cat allergen above 1 μg/g of dust were found in 12.7% of homes, and 3.3% of homes contained Fel d 1 levels greater than 8 μg/g of dust. The majority of children (75.0%) with reported ownership of dogs were exposed to Can f 1 levels above 2 μg/g of house dust, and 73.1% of children with cats at home were exposed to Fel d 1 concentrations above 1 μg/g house dust. The results of the study showed that post-test probability of the true exposure to Can f 1 above 2 μg/g dust in houses with positive interview on indoor dogs was 75.0% (95%CI: 61.7–84.8%). On the other hand, the prediction of exposure estimated from the interview data on indoor dogs produced 12.6% of false negatives (95% CI: 9.9–15.8%). Similarly, the post-test probability of the true exposure to Fel d 1 above 1 μg/g dust in houses with positive interview on indoor cats was 73.1% (95%CI: 55.1–85.7%). On the other hand, the interview data produced 6.4% false negatives (95% CI: 4.6–9.0%). In conclusion, the study demonstrated that homes in Poland with pet ownership are important reservoir of Can f 1 and Fel d 1 allergens with levels that might induce allergic symptoms. Even in homes of children without a dog or cat indoors, there was a higher prevalence of pet allergens at the levels above allergic sensitisation thresholds. This may have an important implication for epidemiologic studies on pet related allergy and prevention practice.
The tumor supressor function of STGC3 and its reduced expression in nasopharyngeal carcinoma
Authors: He Xiu-Sheng , Deng Min , Yang Shuai , Xiao Zhi-Qiang , Luo Qiao , He Zhi-min , Hu Bo , Chen Zhu-Chu 
Published: March 2008

AbstractSTGC3 is a novel candidate tumor suppressor gene that was found to be associated with nasopharyngeal carcinoma (NPC) via the cDNA cloning and RACE processes. The biological function of the STGC3 protein and its expression level in nasopharyngeal carcinoma remain unknown. This study aimed to evaluate the STGC3 protein expression level in NPC and to investigate the inhibitory function of STGC3 as a candidate tumor suppressor gene. We assessed the expression of the STGC3 protein in NPC biopsies and normal control specimens via Western blot and immunohistochemical analysis. The expression of STGC3 as induced by doxycycline (Dox) via a tetracycline (Tet)-regulated system in human nasopharyngeal carcinoma cell line CNE2 was also established, and the effect of STGC3 restoration on the biological behavior of CNE2 was observed. A reduced level of STGC3 expression (0.978 ± 0.213 versus 0.324 ± 0.185, P < 0.05) was detected in NPC versus normal nasopharyngeal tissue by Western blot assay. Immunohistochemical assays for STGC3 detected positive staining in the nuclei and cytoplasm of epithelial cells, and the positive expression rate in NPC, 8 of 21 (38%), was lower than that in normal nasopharynx samples, 16 of 22 (72%). After STGC3 expression was restored, the growth capacity and clone formation potential of CNE2 cells in soft agar were significantly suppressed, and the cell percentage in G0/G1 phase increased, while the percentage of cells entering the S and G2 phases decreased. This indicates that an abnormality in STGC3 expression is associated with nasopharyngeal carcinogenesis and that it may play an important role in controlling cell growth and regulating the cell cycle.
The Effect of Classroom Structure on Shared Perceptions of Ability
Authors: Rosenholtz Susan J. , Wilson Bruce 
Published: March 2008

The degree of ability differentiation—shared understandings of ability differences—which occurs in classrooms, can be theoretically attributed to the uniformity of criteria comparing students and to the number of dimensions on which those criteria are applied. We identify a cluster of classroom characteristics, labeled “classroom resolution,” hypothesized to produce variation in the degree of ability differentiation: grouping practice, teacher evaluation practice, task differentiation, and student autonomy. Surveying upper-grade students and teachers from seven low resolution and eight high resolution classrooms, we find that consensus on an individual’s academic ranking is higher among classmates, between classmates and self, between teacher and classmates, and between teacher and self in high resolution classrooms. The results suggest that classrooms, varied by resolution, provide different interpretations of ability.
Limitations of Recent Research Relating Piaget’s Theory to Adolescent Thought
Authors: Nagy Philip , Griffiths Alan K. 
Published: March 2008

Educators have been interested in Jean Piaget’s theory of cognitive development as a means of linking developmental level, concepts that can be grouped, and instructional strategy. Also, considerable effort has been directed to acceleration of the child’s developmental level. Many researchers, wishing to generalize to large numbers, have turned away from Piaget’s technique to group paper-and-pencil tests. Attention has been focused on the psychometric properties of these tests and their statistical links with other constructs. This review takes the following perspectives. First, there is a questionable relationship between the observed products of mental effort and their underlying mental strategies. There is evidence of a many-many rather than a one-one relationship between solution and strategy. Second, when viewed from its own experimental statistical perspective, much of the research suffers from serious methodological flaws. Third, attempts to prescribe instructional strategies that accelerate intellectual development have borne little fruit. The review closes with suggestions for a redirection of emphasis on the application of Piaget’s theory to education.
Balancing - Analysis of Variance by Another Name
Authors: Appelbaum Mark I. , Cramer Elliot M. 
Published: March 2008

In Report 7 (1971) of the National Assessment of Educational Progress, an analytic technique known as balancing was introduced. The stated purpose of this technique is the elimination of confounding in multifactor survey studies in which some attributes are not equally represented in all cells of the survey sample design. The likely impact of the NAEP reports is great, and it is vital that the nature of the analyses and their relationships to other known analytic techniques be clearly understood. This report shows that the estimation procedure used in balancing is the equivalent of that employed in the nonorthogonal analysis of variance in an additive model. The nature of weighting schemes for the definition of marginal populations is considered in detail as well as the implications of these various schemes to interpretation of results. The results on weighting schemes and interpretations apply to both balancing and a much broader class of analyses.
Development of the Science of Catalysis
Authors: Davis Burtron H. 
Published: March 2008

Abstract
The sections in this article are

Early Concepts: Berzelius, Liebig, and Faraday

Wilhelm Ostwald

The Concepts of Kinetics and Intermediate Compounds

Negative Catalysis: Autocatalysis

Adsorption

Active Site: Geometric or Electronic?

Selected Systems

Ammonia Synthesis

Acid Catalysis

Zeolites

Ions in Catalysis

Hydrogenation

Oxidation

Summary