Displacement of methane by coadsorbed carbon dioxide is facilitated in narrow carbon nanopores

By using simulation methods, we studied the adsorption of binary CO2-CH4 mixtures on various CH4 preadsorbed carbonaceous materials (e.g., triply periodic carbon minimal surfaces, slit-shaped carbon micropores, and Harris's virtual porous carbons) at 293 K. Regardless of the different micropore geometry, two-stage mechanism of CH4 displacement from carbon nanospaces by coadsorbed CO2 has been proposed. In the first stage, the coadsorbed CO2 molecules induced the enhancement of CH4 adsorbed amount. In the second stage, the stronger affinity of CO2 to flat/curved graphitic surfaces as well as CO2-CO2 interactions cause the displacement of CH4 molecules from carbonaceous materials. The operating conditions of CO2-induced cleaning of the adsorbed phase from CH4 mixture component strongly depend on the size of the carbon micropores, but, in general, the enhanced adsorption field in narrow carbon ultramicropores facilitates the nonreactive displacement of CH4 by coadsorbed CO2. This is because in narrow carbon ultramicropores the equilibrium CO2/CH4 selectivity (i.e., preferential adsorption toward CO2) increased significantly. The adsorption field in wider micropores (i.e., the overall surface energy) for both CO2 and CH4 is very similar, which decreases the preferential CO2 adsorption. This suppresses the displacement of CH4 by coadsorbed CO2 and assists further adsorption of CH4 from the bulk mixture (i.e., CO2/CH4 mixing in adsorbed phase).

New age estimates for the Palaeolithic assemblages and Pleistocene succession of Casablanca, Morocco

Marine and aeolian Quaternary sediments from Casablanca, Morocco were dated using the optically stimulated luminescence (OSL) signal of quartz grains. These sediments form part of an extensive succession spanning the Pleistocene, and contain a rich faunal and archaeological record, including an Acheulian lithic assemblage from before the Brunhes–Matayama boundary, and a Homo erectus jaw from younger cave deposits. Sediment samples from the sites of Reddad Ben Ali, Oulad J’mel, Sidi Abderhamane and Thomas Quarries have been dated, in order to assess the upper limits of OSL. The revision of previously measured mammalian tooth enamel electron spin resonance (ESR) dates from the Grotte des Rhinocéros, Oulad Hamida Quarry 1, incorporating updated environmental dose rate measurements and attenuation calculations, also provide chronological constraint for the archaeological material preserved at Thomas Quarries. Several OSL age estimates extend back to around 500,000 years, with a single sample providing an OSL age close to 1 Ma in magnetically reversed sediments. These luminescence dates are some of the oldest determined, and their reliability is assessed using both internal criteria based on stratigraphic consistency, and external lithostratigraphic, morphostratigraphic and independent chronological constraints. For most samples, good internal agreement is observed using single aliquot regenerative-dose OSL measurements, while multiple aliquot additive-dose measurements generally have poorer resolution and consistency. Novel slow-component and component-resolved OSL approaches applied to four samples provide significantly enhanced dating precision, and an examination of the degree of signal zeroing at deposition. A comparison of the OSL age estimates with the updated ESR dates and one U-series date demonstrate that this method has great potential for providing reliable age estimates for sediments of this antiquity. We consider the cause of some slight age inversion observed at Thomas Quarries, and provide recommendations for further luminescence dating within this succession.

Extensive and intensive globalizations: explicating the low connectivity puzzle of U.S. cities using a city-dyad analysis

This article reports an experiment in world city network analysis focusing on city-dyads. Results are derived from an unusual principal components analysis of 27,966 city-dyads across 5 advanced producer service sectors. A 2-component solution is found that identifies different forms of globalization: extensive and intensive. The latter is characterized by very high component scores and describes the more important city-dyads focused upon London-New York (NYLON). The extensive globalization component heavily features London and New York but with each linked to less important cities. U.S. cities score relatively high on the intensive globalization component and we use this finding to explain the low connectivities of U.S. cities in previous studies of the world city network. The two components are tentatively interpreted in world-systems terms: intensive globalization is the process of core-making through city-dyads; extensive globalization is the process of linking core with non-core through city-dyads.

Walking in a winter wonderland? Strategies for Early and Middle Pleistocene survival in mid-latitude Europe

Any occupation of northern Europe by Lower Palaeolithic hominins, even those occurring during full interglacials, must have addressed the challenges of marked seasonality and cold winters. These would have included the problems of: wind-chill and frostbite; duration, distribution and depth of snow-cover; reduced daylight hours; and distribution and availability of animal and plant foods. Solutions can essentially be characterised as a ‘stick or twist’ choice: i.e. year-round presence on a local scale vs. extensive annual mobility. However these options, and the ‘interim’ strategies that lie between them, present various problems, including maintaining core body temperature, meeting the energetic demands of mobility, coping with reduced resource availability and increasing patchiness, and meeting nutritional requirements. The feasibility of different winter survival strategies are explored with reference to Lower Palaeolithic palaeoenvironmental reconstructions and on-site behavioural evidence. Emphasis is placed upon possible strategies for (i) avoiding the excessive lean meat protein problem of ‘rabbit starvation’ (e.g. through exploitation of ‘residential’ species with significant winter body fat and/or by targeting specific body parts, following modern ethnographic examples, supplemented by the exploitation of winter plants); and (ii) maintaining body temperatures (e.g. through managed pyrotechnology, and/or other forms of cultural insulation). The paper concludes with a suggested winter strategy.

Changing attitudes, beliefs and feelings towards food in bulimic patients

Eating attitudes are defined as beliefs. thoughts, feelings and behaviors towards food. Bulimia nervosa (BN) is ail eating disorder, in which the eating, attitudes are Seriously disturbed. Studies that evaluated nutritional aspects of BN focus mainly oil food intake, dietary restriction and binge eating. while the follow-up Studies evaluate mainly clinical symptoms. The objective of this study was to evaluate eating attitudes of patients with BN. during and after cognitive-behavioral intervention. Thirty nine (39) BN female patients received cognitive behavioral treatment with a Multidisciplinary team and had eating attitudes assessed by a questionnaire developed for this research. Frequencies of the attitudes assessed were compared at baseline. after 12 weeks and 24 weeks of treatment. After treatment, patients had less distorted beliefs about food, less guilty after eating ""forbidden"" foods and they felt more tranquil while caring outside home. Other negative behaviors, as dietary restriction, the desire of not cat, being angry when feeling hungry and using the food to relive stress. persisted. Eating attitudes of patients with BN are hard to be changed in a short-term. More attention to this disease`s component and new approaches to treatment are needed in order to have a better recovery.

Supercritical fluid extracts from the Brazilian cherry (Eugenia uniflora L.): Relationship between the extracted compounds and the characteristic flavour intensity of the fruit

Supercritical carbon dioxide (SC-CO(2)) extractions of Brazilian cherry (Eugenia uniflora L.) were carried out under varied conditions of pressure and temperature, according to a central composite 2(2) experimental design, in order to produce flavour-rich extracts. The composition of the extracts was evaluated by gas chromatography coupled with mass spectrometry (GC/MS). The abundance of the extracted compounds was then related to sensory analysis results, assisted by principal component and factorial discriminant analysis (PCA and FDA, respectively). The identified sesquiterpenes and ketones were found to strongly contribute to the characteristic flavour of the Brazilian cherry. The extracts also contained a variety of other volatile compounds, and part of the fruit wax contained long-chain hydrocarbons that according to multivariate analysis, contributed to the yield of the extracts, but not the flavour. Volatile phenolic compounds, to which antioxidant properties are attributed, were also present in the extracts in high proportion, regardless of the extraction conditions. (C) 2010 Elsevier Ltd. All rights reserved.

Modeling hourly and daily fractions of UV, PAR and NIR to global solar radiation under various sky conditions at Botucatu, Brazil

In this analysis, using available hourly and daily radiometric data performed at Botucatu, Brazil, several empirical models relating ultraviolet (UV), photosynthetically active (PAR) and near infrared (NIR) solar global components with solar global radiation (G) are established. These models are developed and discussed through clearness index K(T) (ratio of the global-to-extraterrestrial solar radiation). Results obtained reveal that the proposed empirical models predict hourly and daily values accurately. Finally. the overall analysis carried Out demonstrates that the sky conditions are more important in developing correlation models between the UV component and the global solar radiation. The linear regression models derived to estimate PAR and NIR components may be obtained without sky condition considerations within a maximum variation of 8%. In the case of UV, not taking into consideration the sky condition may cause a discrepancy of up to 18% for hourly values and 15% for daily values. (C) 2008 Elsevier Ltd. All rights reserved.

TAF15 and the leukemia-associated fusion protein TAF15-CIZ/NMP4 are cleaved by caspases-3 and-7

Caspases are central players in proteolytic pathways that regulate cellular processes Such as apoptosis and differentiation. To accelerate the discovery of novel caspase substrates we developed a method combining in silico screening and in vitro validation. With this approach, we identified TAH15 as a novel caspase Substrate in a trial Study. We find that TAF15 was specifically cleaved by caspases-3 and -7. Site-directed mutagenesis revealed the consensus sequence (106)DQPD/Y(110) as the only site recognized by these caspases. Surprisingly, TAF15 was cleaved at more than one site in staurosporine-treated Jurkat cells. In addition, we generated two oncogenic TAF15-CIZ/NMP4-fused proteins which have been found in acute myeloid leukemia and demonstrate that caspases-3 and -7 cleave the fusion proteins at one single site. Broad application of this combination approach should expedite identification of novel caspase-interacting proteins and provide new insights into the regulation of caspase pathways leading to cell death in normal and cancer cells. (C) 2009 Elsevier Inc. All rights reserved.

Up-regulation of NADPH oxidase components and increased production of interferon-gamma by leukocytes from sickle cell disease patients

We have previously demonstrated that mononuclear leukocytes from patients with sickle cell disease (SCD) release higher amounts of superoxide compared with normal controls. The aim of this study was to further study the NADPH oxidase system in these patients by investigating gene expression of NADPH oxidase components, phosphorylation of p47(phox) component, and the release of cytokines related to NADPH oxidase activation in mononuclear leukocytes from patients with SCD. gp91(phox) gene expression was significantly higher in monocytes from SCD patients compared with normal controls (P = 0.036). Monocytes from SCD patients showed higher levels of p47 phox phosphorylation compared with normal controls. INF-gamma release by lymphocytes from SCD patients was significantly higher compared with normal controls, after 48 h culture with phytohemagglutinin (P = 0.02). The release of TNF-alpha by monocytes from SCD patients and normal controls was similar after 24 and 48 h culture with lipopolysaccharide (P > 0.05). We conclude that monocytes from SCD patients show higher levels of gp91(phox) gene expression and p47(phox) phosphorylation, along with increased IFN-gamma release by SCD lymphocytes. These findings help to explain our previous observation showing the increased respiratory burst activity of mononuclear leukocytes from SCD patients and may contribute to inflammation and tissue damage in these patients.

Disruption of Saccharomyces cerevisiae by Plantaricin 149 and investigation of its mechanism of action with biomembrane model systems

The action of a synthetic antimicrobial peptide analog of Plantaricin 149 (Pln149a) against Saccharomyces cerevisiae and its interaction with biomembrane model systems were investigated. Pln149a was shown to inhibit S. cerevisiae growth by more than 80% in YPD medium, causing morphological changes in the yeast wall and remaining active and resistant to the yeast proteases even after 24 h of incubation. Different membrane model systems and carbohydrates were employed to better describe the Pln149a interaction with cellular components using circular dichroism and fluorescence spectroscopies, adsorption kinetics and surface elasticity in Langmuir monolayers. These assays showed that Pln149a does not interact with either mono/polysaccharides or zwitterionic LUVs, but is strongly adsorbed to and incorporated into negatively charged surfaces, causing a conformational change in its secondary structure from random-coil to helix upon adsorption. From the concurrent analysis of Pln149a adsorption kinetics and dilatational surface elasticity data, we determined that 2.5 mu M is the critical concentration at which Pln149a will disrupt a negative DPPG monolayer. Furthermore, Pln149a exhibited a carpet-like mechanism of action, in which the peptide initially binds to the membrane, covering its surface and acquiring a helical structure that remains associated to the negatively charged phospholipids. After this electrostatic interaction, another peptide region causes a strain in the membrane, promoting its disruption. (C) 2009 Elsevier B.V. All rights reserved.

Molecular Basis of the Thermostability and Thermophilicity of Laminarinases: X-ray Structure of the Hyperthermostable Laminarinase from Rhodothermus marinus and Molecular Dynamics Simulations

Glycosyl hydrolases are enzymes capable of breaking the glycosidic linkage of polysaccharides and have considerable industrial and biotechnological applications. Driven by the later applications, it is frequently desirable that glycosyl hydrolases display stability and activity under extreme environment conditions, such as high temperatures and extreme pHs. Here, we present X-ray structure of the hyperthermophilic laminarinase from Rhodothermus marinus (RmLamR) determined at 1.95 angstrom resolution and molecular dynamics simulation studies aimed to comprehend the molecular basis, for the thermal stability of this class of enzymes. As most thermostable proteins, RmLamR contains a relatively large number of salt bridges, which are not randomly distributed on the structure. On the contrary, they form clusters interconnecting beta-sheets of the catalytic domain. Not all salt bridges, however, are beneficial for the protein thermostability: the existence of charge-charge interactions permeating the hydrophobic core of the enzymes actually contributes to destabilize the structure by facilitating water penetration into hydrophobic cavities, as can be seen in the case of mesophilic enzymes. Furthermore, we demonstrate that the mobility of the side-chains is perturbed differently in each class of enzymes. The side-chains of loop residues surrounding the catalytic cleft in the mesophilic laminarinase gain mobility and obstruct the active site at high temperature. By contrast, thermophilic laminarinases preserve their active site flexibility, and the active-site cleft remains accessible for recognition of polysaccharide substrates even at high temperatures. The present results provide structural insights into the role played by salt-bridges and active site flexibility on protein thermal stability and may be relevant for other classes of proteins, particularly glycosyl hydrolases.

A new class of survival regression models with heavy-tailed errors: robustness and diagnostics

Birnbaum-Saunders models have largely been applied in material fatigue studies and reliability analyses to relate the total time until failure with some type of cumulative damage. In many problems related to the medical field, such as chronic cardiac diseases and different types of cancer, a cumulative damage caused by several risk factors might cause some degradation that leads to a fatigue process. In these cases, BS models can be suitable for describing the propagation lifetime. However, since the cumulative damage is assumed to be normally distributed in the BS distribution, the parameter estimates from this model can be sensitive to outlying observations. In order to attenuate this influence, we present in this paper BS models, in which a Student-t distribution is assumed to explain the cumulative damage. In particular, we show that the maximum likelihood estimates of the Student-t log-BS models attribute smaller weights to outlying observations, which produce robust parameter estimates. Also, some inferential results are presented. In addition, based on local influence and deviance component and martingale-type residuals, a diagnostics analysis is derived. Finally, a motivating example from the medical field is analyzed using log-BS regression models. Since the parameter estimates appear to be very sensitive to outlying and influential observations, the Student-t log-BS regression model should attenuate such influences. The model checking methodologies developed in this paper are used to compare the fitted models.

Preparation and characterization of colloidal Ni(OH)(2)/bentonite composites

A conductive and electrochemically active composite material has been prepared by the combination of bentonite and nickel hydroxide precursor sol. This material exhibits the characteristic intercalation properties of the clay component and the electrochemical and optical properties of nickel hydroxide. The clay particles seem to induce the aggregation of nickel hydroxide, leading to the formation of a layer of alpha-Ni(OH)(2) exhibiting needle like morphology. The composite forms stable films and has been conveniently used for the preparation of modified electrodes exhibiting intercalation and electrochemical properties, thus providing an interesting material for the development of amperometric sensors. (C) 2008 Elsevier Ltd. All rights reserved.