bluuebunny/crossref_metadata_2025 huggingface dataset:
Gαi2 and ZAP-70 Mediate RasGRP1 Membrane Localization and Activation of SDF-1–Induced T Cell Functions
Authors: Kremer Kimberly N. , Kumar Ashok , Hedin Karen E.
Published: August 2011

RasGRP1, a Ras guanine-nucleotide exchange factor, critically mediates T cell development and function and controls immunodeficiency and autoimmunity. In this study, we describe a unique mechanism of mobilization and activation of RasGRP1 in response to SDF-1, a chemokine that signals via the G protein-coupled receptor CXCR4. Depletion of RasGRP1 impaired SDF-1–stimulated human T cell migration, expression of the activation marker CD69, and activation of the ERK MAPK pathway, indicating that RasGRP1 mediates SDF-1 functions. SDF-1 treatment caused RasGRP1 to localize to the plasma membrane to activate K-Ras and to the Golgi to activate N-Ras. These events were required for cellular migration and for ERK activation that mediates downstream transcriptional events in response to SDF-1. SDF-1–dependent localization of RasGRP1 did not require its diacylglycerol-binding domain, even though diacyglycerol was previously shown to mediate localization of RasGRP1 in response to Ag stimulation. This domain was, however, required for activity of RasGRP1 after its localization. Intriguingly, SDF-1 treatment of T cells induced the formation of a novel molecular signaling complex containing RasGRP1, Gαi2, and ZAP-70. Moreover, SDF-1–mediated signaling by both Gi proteins and ZAP-70 was required for RasGRP1 mobilization. In addition, RasGRP1 mobilization and activation in response to SDF-1 was dependent on TCR expression, suggesting that CXCR4 heterodimerizes with the TCR to couple to ZAP-70 and mobilize RasGRP1. These results increase understanding of the molecular mechanisms that mediate SDF-1 effects on T cells and reveal a novel mechanism of RasGRP1 regulation. Other G protein-coupled receptors may similarly contribute to regulation of RasGRP1.
Simvastatin Inhibits IFN Regulatory Factor 4 Expression and Th17 Cell Differentiation in CD4+ T Cells Derived from Patients with Multiple Sclerosis
Authors: Zhang Xin , Tao Yazhong , Troiani Luigi , Markovic-Plese Silva
Published: August 2011

Subsequent to the clinical trial of simvastatin in patients with relapsing remitting multiple sclerosis (RR MS), which demonstrated the ability of simvastatin to inhibit new inflammatory CNS lesion formation, the current in vitro study has characterized the mechanisms through which simvastatin inhibits Th17 cell differentiation. The anti-inflammatory effects of statins are mediated by the inhibition of isoprenylation, which ensures proper membrane insertion and function of proteins. Small GTPases, involved in multiple signal transduction pathways, are the key targets for isoprenylation. We report that simvastatin, one of the most hydrophobic statins with good CNS penetration, inhibited Th17 cell differentiation and IL-17A, IL-17F, IL-21, and IL-22 secretion in in vitro-differentiated naive CD4+ T cells from RR MS patients. Simvastatin exerted a less prominent effect on the cells from healthy controls, as it inhibited only IL-17F secretion. The inhibition of Th17 cell differentiation was mediated via inhibition of IFN regulatory factor 4 (IRF4) expression, which was identified as a key transcription factor for human Th17 cell differentiation using both IRF4 gene knockdown and overexpression experiments. In studies addressing which isoprenylation pathway—geranylgeranylation or farnesylation—is inhibited by simvastatin, we demonstrated that the geranylgeranyl transferase inhibitor replicated the effect of simvastatin. Selective inhibition of geranylgeranylated RhoA-associated kinase replicated the effect of simvastatin on the inhibition of IRF4 expression and IL-17A, IL-17F, IL-21, and IL-22 secretion, presenting a promising new therapeutic approach for this disabling disease.
HIV-Mediated Phosphatidylinositol 3-Kinase/Serine–Threonine Kinase Activation in APCs Leads to Programmed Death-1 Ligand Upregulation and Suppression of HIV-Specific CD8 T Cells
Authors: Muthumani Karuppiah , Shedlock Devon J. , Choo Daniel K. , Fagone Paolo , Kawalekar Omkar U. , Goodman Jonathan , Bian Chaoran B. , Ramanathan Aarti A. , Atman Parikh , Tebas Pablo , Chattergoon Michael A. , Choo Andrew Y. , Weiner David B.
Published: August 2011

Recent evidence demonstrates that HIV-1 infection leads to the attenuation of cellular immune responses, which has been correlated with the increased expression of programmed death (PD)-1 on virus-specific CD8+ T cells. PD-1 is induced upon T cell activation, and its prolonged expression facilitates CD8+ T cell inhibitory signals when bound to its B7 family ligands, PD-ligand (L)1/2, which are expressed on APCs. Importantly, early reports demonstrated that blockade of the PD-1/PD-L interaction by Abs may help to counter the development of immune exhaustion driven by HIV viral persistence. To better understand the regulation of the PD-1 pathway during HIV infection, we examined the ability of the virus to induce PD-L expression on macrophages and dendritic cells. We found a direct relationship between the infection of APCs and the expression of PD-L1 in which virus-mediated upregulation induced a state of nonresponsiveness in uninfected HIV-specific T cells. Furthermore, this exhaustion phenotype was revitalized by the blockade of PD-L1, after which T cells regained their capacity for proliferation and the secretion of proinflammatory cytokines IFN-γ, IL-2, and IL-12 upon restimulation. In addition, we identify a critical role for the PI3K/serine–threonine kinase signaling pathway in PD-L1 upregulation of APCs by HIV, because inhibition of these intracellular signal transducer enzymes significantly reduced PD-L1 induction by infection. These data identify a novel mechanism by which HIV exploits the immunosuppressive PD-1 pathway and suggest a new role for virus-infected cells in the local corruption of immune responses required for viral suppression.
Structural Basis for FcγRIIa Recognition of Human IgG and Formation of Inflammatory Signaling Complexes
Authors: Ramsland Paul A. , Farrugia William , Bradford Tessa M. , Sardjono Caroline Tan , Esparon Sandra , Trist Halina M. , Powell Maree S. , Tan Peck Szee , Cendron Angela C. , Wines Bruce D. , Scott Andrew M. , Hogarth P. Mark
Published: August 2011

The interaction of Abs with their specific FcRs is of primary importance in host immune effector systems involved in infection and inflammation, and are the target for immune evasion by pathogens. FcγRIIa is a unique and the most widespread activating FcR in humans that through avid binding of immune complexes potently triggers inflammation. Polymorphisms of FcγRIIa (high responder/low responder [HR/LR]) are linked to susceptibility to infections, autoimmune diseases, and the efficacy of therapeutic Abs. In this article, we define the three-dimensional structure of the complex between the HR (arginine, R134) allele of FcγRIIa (FcγRIIa-HR) and the Fc region of a humanized IgG1 Ab, hu3S193. The structure suggests how the HR/LR polymorphism may influence FcγRIIa interactions with different IgG subclasses and glycoforms. In addition, mutagenesis defined the basis of the epitopes detected by FcR blocking mAbs specific for FcγRIIa (IV.3), FcγRIIb (X63-21), and a pan FcγRII Ab (8.7). The epitopes detected by these Abs are distinct, but all overlap with residues defined by crystallography to contact IgG. Finally, crystal structures of LR (histidine, H134) allele of FcγRIIa and FcγRIIa-HR reveal two distinct receptor dimers that may represent quaternary states on the cell surface. A model is presented whereby a dimer of FcγRIIa-HR binds Ag–Ab complexes in an arrangement that possibly occurs on the cell membrane as part of a larger signaling assembly.
Stroke in the Very Old: A Systematic Review of Studies on Incidence, Outcome, and Resource Use
Authors: Russo Tommasina , Felzani Giorgio , Marini Carmine
Published: August 2011

Background and Purpose. Stroke incidence increases with age and is likely to increase in the aging populations. We investigated incidence, outcome, and resource use in very old subjects with stroke.Methods. We performed a systematic review of available data through electronic search of the literature databases and manual search of reference lists. Data were extracted for the age groups of over 80, 80 to 84 years old, and over 85. Overall incidence rates, expressed as the number of first strokes per 1000 person-years, were estimated using Poisson regression analysis. Odds ratios for the comparisons between subjects over and under 80 were calculated with the Mantel-Haenszel method.Results. We found a high incidence of stroke in the very old. The estimated incidence rates were 20.78 (95% CI 19.69 to 21.87) in subjects over 80, 17.23 (95% CI 15.97 to 18.49) for those 80 to 85 years old, and 20.78 (95% CI 16.74 to 23.78) for those over 85. Subjects over 80 contributed 29.95% of strokes; rates were similar among genders. Thirty-day case fatality rate and occurrence of dependency were higher in subjects over 80, although associated with less frequent hospital and stroke unit admission and less diagnostic resource use.Conclusions. The contribution of very old subjects to the global burden of stroke is relevant and may require efficient dedicated stroke services.
Prostatic Adenocarcinoma Metastatic to Pleomorphic Liposarcoma, a “Collision Phenomenon”: Report of a Case with Review of Pelvic Collision Tumors
Authors: Roy Somak , Hrebinko Ronald L. , Cieply Kathleen M. , Parwani Anil V. , Rao Uma N. M.
Published: August 2011

“Collision tumor” is an uncommon phenomenon characterized by coexistence of two completely distinct and independent tumors at the same site. Collision tumors have been reported in different sites in the body; however, these are particularly uncommon in the pelvic cavity. A 70-year-old man, with prior history of urothelial and prostate cancer, presented with a large pelvic mass detected on imaging studies. Pathological examination revealed a large liposarcoma with prostatic carcinoma embedded in it. Immunohistochemistry and florescence in situ hybridization studies were performed to reach to a conclusive diagnosis. To the best of our knowledge, this is the second case reported till date. We present the challenges encountered in the diagnosis of this case and review of pelvic collision tumors.
Intensity of Oestrus Signalling Is the Most Relevant Indicator for Animal Well-Being in High-Producing Dairy Cows
Authors: Garcia Emanuel , Hultgren Jan , Fällman Pontus , Geust Johanna , Algers Bo , Stilwell George , Gunnarsson Stefan , Rodriguez-Martinez Heriberto
Published: August 2011

Full signalling of oestrous behaviour is vital for proper timing of AI and good reproductive performance, currently jeopardized by shorter observations of oestrus behaviour. Alternative indicators including progesterone (P4) recordings on-farm are tested. Oestrous intensity of 37 heifers (H) and 30 1st-parity dairy cows (C1) either Swedish Red (32) or Swedish Holstein (35) with high genetic potential for milk production, was studied in relation to AI. P4-levels in blood or milk were monitored on-farm at 0, 7, and 20 d post-AI with a portable ELISA reader (eProCheck800). Avoidance distance and body condition were scored at day 7, and pregnancy diagnosed by P4(day 20) and trans-rectal palpation (day 50). More heifers (46%) than C1-cows (10%) showed standing oestrus (strongest intensity,P<0.05), leading to higher pregnancy rate at d50 (72% versus 37% for C1,P<0.01) and calving rate (H: 64%, C1: 33%,P<0.05). Avoidance distances were short (<1 m), reflecting good human-animal interaction. Visually-recorded standing oestrus yielded 4.8 fold higher odds of pregnancy, respectively 4.6-fold higher odds of calving. On-farm P4-recordings had complementary value yet less accuracy. Intensity of oestrus signalling relates to animal well-being, reflected in pregnancy-to-term being a good indicator for optimal welfare in high-producing dairy cattle.
Preclinical Studies on Mesenchymal Stem Cell-Based Therapy for Growth Plate Cartilage Injury Repair
Authors: Chung Rosa , Foster Bruce K. , Xian Cory J.
Published: August 2011

In the last two decades, there has been a strong interest in searching for biological treatments for regeneration of injured growth plate cartilage and prevention of its bony repair. Various means have been tried, including implantation of chondrocytes, mesenchymal stem cell (MSC), together with exogenous growth factor and scaffolds, and gene therapy. However, with the lack of success with chondrocytes, more research has focussed on MSC-based treatments. In addition to circumvent limitations with MSC-based treatments (including cell harvest-associated morbidity, difficulties/time/cost involved in MSC isolation andex vivoexpansion, and potential disease transmission), mobilising endogenous MSCs to the growth plate injury site and enhancingin situregeneration mechanisms would represent an alternative attractive approach. Further studies are required to investigate the potential particularly in large animal models or clinical setting of theex vivoMSC approach and the feasibility of the endogenous MSCin situapproach in growth plate regeneration.
Laboratory Surveillance of Rabies in Humans, Domestic Animals, and Bats in Madagascar from 2005 to 2010
Authors: Reynes Jean-Marc , Andriamandimby Soa Fy , Razafitrimo Girard Marcelin , Razainirina Josette , Jeanmaire Elisabeth Marie , Bourhy Hervé , Heraud Jean-Michel
Published: August 2011

Background. Rabies virus (RABV) has circulated in Madagascar at least since the 19th century.Objectives. To assess the circulation of lyssavirus in the island from 2005 to 2010.Materials and Methods. Animal (including bats) and human samples were tested for RABV and other lyssavirus using antigen, ribonucleic acid (RNA), and antibodies detection and virus isolation.Results. Half of the 437 domestic or tame wild terrestrial mammal brains tested were found RABV antigen positive, including 54% of the 341 dogs tested. This percentage ranged from 26% to 75% across the period. Nine of the 10 suspected human cases tested were laboratory confirmed. RABV circulation was confirmed in 34 of the 38 districts sampled. No lyssavirus RNA was detected in 1983 bats specimens. Nevertheless, antibodies against Lagos bat virus were detected in the sera of 12 among 50Eidolon dupreanumspecimens sampled.Conclusion. More than a century after the introduction of the vaccine, rabies still remains endemic in Madagascar.
Histopathological and Genomic Grading Provide Complementary Prognostic Information in Breast Cancer: A Study on Publicly Available Datasets
Authors: Chowdhury Nilotpal
Published: August 2011

The genomic grade (GG) for breast cancer is thought to be the genomic counterpart of histopathological grade (HG). The motivation behind this study was to see whether HG retains its prognostic impact even when adjusted for GG, or whether it can be replaced by the latter. Four publicly available gene expression datasets were analyzed. Kaplan-Meier curves, log rank test, and Cox regression were used to study recurrence-free survival (RFS) and distant metastasis-free survival (DMFS). HG remained a significant prognostic indicator in low GG tumors (P = 0.003 for DMFS, P< 0.001 for RFS) but not in high GG tumors. HG grade 2 tumors differed significantly from HG grade 1 tumors, underlining the prognostic role of intermediate HG tumors. Additionally, GG could stratify HG 1 as well as HG 2 tumors into distinct prognostic groups. HG and GG add independent prognostic information to each other. However, the prognostic effects of both HG and GG are time varying, with the hazard ratios of high HG and GG tumors being markedly attenuated over time.
Indigenous farmers' rights, international agricultural trade and the WTO
Authors: Smith Fiona
Published: August 2011

Peasant and family farmers' activist groups argue that only indigenous farming practices can guarantee adequate food supplies without loss of biodiversity. Such activists argue that the international agricultural trade rules in the WTO should therefore recognise indigenous farmers' rights to farm in this way because it has such a positive impact. This article considers whether the WTO's rules on international agricultural trade contained in the WTO Agreement on Agriculture and the proposed changes to those rules from the Doha Draft Modalities on Agriculture give such rights to indigenous farmers. It argues that the WTO rules do not give such rights and that there is no prospect of amending the rules either, as there is no linguistic space in the WTO scheme to talk about indigenous farmers in this way. The WTO scheme is simply incapable of according such rights. Instead, indigenous farmers are seen as ‘victims’ of liberalisation who can be protected by the state against the progressive move towards ‘better’ agricultural trade. This protection is designed to allow farmers to adjust their agricultural production to the growing demand for, for example, food and biofuels. The farmer may benefit from the protection of the rules but will never become a rights-holder per se. The power to protect remains with the state and direct normative entitlement never resides in the farmer.
You are what you eat: market citizens and the right to know about nano foods
Authors: Stokes Elen
Published: August 2011

This article considers the role of consumers in the regulation of nanotechnology. The principal regulatory response to nanotechnology to date has been to require the disclosure of information. One such mechanism currently under negotiation in the food sector is the mandatory labelling of nanomaterial ingredients, commonly justified on the ground that consumers have the right to know what they eat. Not only does this provide a vehicle for free market choice but it also offers one of the few routes to citizen engagement in the policy debate. The potential benefits of nano labelling are substantial. As this article seeks to show, however, the demands placed on nano labelling may be difficult to meet because of a range of limiting factors. By highlighting an expectation-capacity gap, this article points to the need for developing a richer choice environment and for scrutinising difficulties not fully addressed in the policy discourse.
Food futures: system transitions towards UK food security
Authors: Lee Robert , Marsden Terry
Published: August 2011

The UK food system, it is argued here, is not sustainable in that it is beset by vulnerabilities and lacks the resilience to overcome these. Focusing on the UK, and relying on earlier empirical data, the nature of these vulnerabilities is explained, as is their impact on the global, carbon-dependent, agro-food system. The earlier data were generated by scenarios of different food futures. These were employed as a research tool, as both their generation and their consideration involved stakeholders concerned with the supply chains for both dairy produce and wheat in the UK. The scenarios and their underpinning methodology are explained by reference to theories of systems' transitions. This article explains how scenarios of this kind can try and capture landscape pressures which might threaten the dominant paradigm and leave room for niche activity to challenge the mainstream. It will also warn, however, that the mainstream will seek to incorporate and marginalise the niche activity. The article concludes that the methodology adopted can draw out critical factors and, in the present case, tease out some early thinking about the nature of transitions towards a more sustainable and resilient system of production and consumption of food.
Cloud condensation nuclei activity and droplet activation kinetics of wet processed regional dust samples and minerals
Authors: Kumar P. , Sokolik I. N. , Nenes A.
Published: August 2011

Abstract. This study reports laboratory measurements of particle size distributions, cloud condensation nuclei (CCN) activity, and droplet activation kinetics of wet generated aerosols from clays, calcite, quartz, and desert soil samples from Northern Africa, East Asia/China, and Northern America. The dependence of critical supersaturation, sc, on particle dry diameter, Ddry, is used to characterize particle-water interactions and assess the ability of Frenkel-Halsey-Hill adsorption activation theory (FHH-AT) and Köhler theory (KT) to describe the CCN activity of the considered samples. Wet generated regional dust samples produce unimodal size distributions with particle sizes as small as 40 nm, CCN activation consistent with KT, and exhibit hygroscopicity similar to inorganic salts. Wet generated clays and minerals produce a bimodal size distribution; the CCN activity of the smaller mode is consistent with KT, while the larger mode is less hydrophilic, follows activation by FHH-AT, and displays almost identical CCN activity to dry generated dust. Ion Chromatography (IC) analysis performed on regional dust samples indicates a soluble fraction that cannot explain the CCN activity of dry or wet generated dust. A mass balance and hygroscopicity closure suggests that the small amount of ions (from low solubility compounds like calcite) present in the dry dust dissolve in the aqueous suspension during the wet generation process and give rise to the observed small hygroscopic mode. Overall these results identify an artifact that may question the atmospheric relevance of dust CCN activity studies using the wet generation method. Based on the method of threshold droplet growth analysis, wet generated mineral aerosols display similar activation kinetics compared to ammonium sulfate calibration aerosol. Finally, a unified CCN activity framework that accounts for concurrent effects of solute and adsorption is developed to describe the CCN activity of aged or hygroscopic dusts.
Abiotic and biotic control of methanol exchanges in a temperate mixed forest
Authors: Laffineur Q. , Aubinet M. , Schoon N. , Amelynck C. , Müller J.-F. , Dewulf J. , Van Langenhove H. , Steppe K. , Heinesch B.
Published: August 2011

Abstract. Methanol exchanges over a mixed temperate forest in the Belgian Ardennes were measured for more than one vegetation season using disjunct eddy-covariance by a mass scanning technique and Proton Transfer Reaction Mass Spectrometry (PTR-MS). Half-hourly methanol fluxes were measured in the range of −0.6 to 0.6 μg m−2 s−1, and net daily methanol fluxes were generally negative in summer and autumn and positive in spring. On average, the negative fluxes dominated (i.e. the site behaved as a net sink), in contrast to what had been found in previous studies. An original model describing the adsorption/desorption of methanol in water films present in the forest ecosystem and the methanol degradation process was developed. Its calibration, based on field measurements, predicted a mean methanol degradation rate of −0.0074 μg m−2 s−1 and a half lifetime for methanol in water films of 57.4 h. Biogenic emissions dominated the exchange only in spring, with a standard emission factor of 0.76 μg m−2 s−1. The great ability of the model to reproduce the long-term evolution, as well as the diurnal variation of the fluxes, suggests that the adsorption/desorption and degradation processes play an important role in the global methanol budget. This result underlines the need to conduct long-term measurements in order to accurately capture these processes and to better estimate methanol fluxes at the ecosystem scale.
Evaluation of TRMM Multi-satellite Precipitation Analysis (TMPA) performance in the Central Andes region and its dependency on spatial and temporal resolution
Authors: Scheel M. L. M. , Rohrer M. , Huggel Ch. , Santos Villar D. , Silvestre E. , Huffman G. J.
Published: August 2011

Abstract. Climate time series are of major importance for base line studies for climate change impact and adaptation projects. However, for instance, in mountain regions and in developing countries there exist significant gaps in ground based climate records in space and time. Specifically, in the Peruvian Andes spatially and temporally coherent precipitation information is a prerequisite for ongoing climate change adaptation projects in the fields of water resources, disasters and food security. The present work aims at evaluating the ability of Tropical Rainfall Measurement Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA) to estimate precipitation rates at daily 0.25° × 0.25° scale in the Central Andes and the dependency of the estimate performance on changing spatial and temporal resolution. Comparison of the TMPA product with gauge measurements in the regions of Cuzco, Peru and La Paz, Bolivia were carried out and analysed statistically. Large biases are identified in both investigation areas in the estimation of daily precipitation amounts. The occurrence of strong precipitation events was well assessed, but their intensities were underestimated. TMPA estimates for La Paz show high false alarm ratio. The dependency of the TMPA estimate quality with changing resolution was analysed by comparisons of 1-, 7-, 15- and 30-day sums for Cuzco, Peru. The correlation of TMPA estimates with ground data increases strongly and almost linearly with temporal aggregation. The spatial aggregation to 0.5°, 0.75° and 1° grid box averaged precipitation and its comparison to gauge data of the same areas revealed no significant change in correlation coefficients and estimate performance. In order to profit from the TMPA combination product on a daily basis, a procedure to blend it with daily precipitation gauge measurements is proposed. Different sources of errors and uncertainties introduced by the sensors, sensor-specific algorithm aspects and the TMPA processing scheme are discussed. This study reveals the possibilities and restrictions of the use of TMPA estimates in the Central Andes and should assist other researchers in the choice of the best resolution-accuracy relationship according to requirements of their applications.
Cornice dynamics and meteorological control at Gruvefjellet, Central Svalbard
Authors: Vogel S. , Eckerstorfer M. , Christiansen H. H.
Published: August 2011

Abstract. Cornice fall avalanches endanger life and infrastructure in Nybyen, a part of Svalbard's main settlement Longyearbyen, located at 78° N in the High Arctic. Thus, cornice dynamics – accretion, cracking and eventual failure – and their controlling meteorological factors were studied along the ridgeline of the Gruvefjellet plateau mountain above Nybyen in the period 2008–2010. Using two automatic time-lapse cameras and hourly meteorological data in combination with intensive field observations on the Gruvefjellet plateau, cornice process dynamics were investigated for larger detail than previously possible. Cornice accretion starts directly following the first snowfall in late September and October, and proceeds throughout the entire snow season under a wide range of air temperature conditions that the maritime winter climate of Svalbard provides. Cornice accretion is particularly controlled by distinct storm events, with a prevailing wind direction perpendicular to the ridge line and average wind speeds from 12 m s−1. Particularly high wind speeds in excess of 30 m s−1 towards the plateau ridgeline lead to cornice scouring and reduce the cornice mass both vertically and horizontally. Induced by pronounced air temperature fluctuations, tension cracks develop between the cornice mass and the plateau. Our measurements indicate a linear crack opening due to snow creep and tilt of the cornice around a pivot point. Four to five weeks elapsed between the first observations of a cornice crack until cornice failure. Throughout the two snow seasons studied, 180 cornice failures were recorded, of which 70 failures were categorized as distinctive cornice fall avalanches. A clear temporal pattern with the majority of cornice failures in June was found. Thus only daily air temperature could determine avalanche from non-avalanche days. Seven large cornice fall avalanches reached the avalanche fans on which the Nybyen settlement is located. The size of the avalanches was primarily determined by the size of the cornice that detached. The improved understanding of the cornice dynamics process provides a first step towards a better predictability of this natural hazard.
Towards Inorganic Porous Materials by Design: Looking for New Architectures
Authors: Medina Manuela E. , Platero‐Prats Ana E. , Snejko Natalia , Rojas Alex , Monge Angeles , Gándara Felipe , Gutiérrez‐Puebla Enrique , Camblor Miguel A.
Published: August 2011

Crystalline porous materials, such as zeolites and metal‐organic frameworks (MOFs), possess a regular and well‐defined system of pores. While zeolites have been known for a long time and are widely used in industry, MOFs are still a new type of compounds with a huge potential for numerous applications. MOFs and zeolites may feature certain similarities as well as large differences, but concepts such as flexibility of the framework, thermodynamic versus kinetic control of the crystallization or stabilizing effect of guest species are key issues in both fields. This article presents a vision on the state of the art of such materials.
Simple, Highly Efficient Vacuum‐Processed Bulk Heterojunction Solar Cells Based on Merocyanine Dyes
Authors: Steinmann Vera , Kronenberg Nils M. , Lenze Martin R. , Graf Steven M. , Hertel Dirk , Meerholz Klaus , Bürckstümmer Hannah , Tulyakova Elena V. , Würthner Frank
Published: August 2011

In order to be competitive on the energy market, organic solar cells with higher efficiency are needed. To date, polymer solar cells have retained the lead with efficiencies of up to 8%. However, research on small molecule solar cells has been catching up throughout recent years and is showing similar efficiencies, however, only for more sophisticated multilayer device configurations. In this work, a simple, highly efficient, vacuum‐processed small molecule solar cell based on merocyanine dyes – traditional colorants that can easily be mass‐produced and purified – is presented. In the past, merocyanines have been successfully introduced in solution‐processed as well as vacuum‐processed devices, demonstrating efficiencies up to 4.9%. Here, further optimization of devices is achieved while keeping the same simple layer stack, ultimately leading to efficiencies beyond the 6% mark. In addition, physical properties such as the charge carrier transport and the cell performance under various light intensities are addressed.
Neuron deficit in the white matter and subplate in periventricular leukomalacia
Authors: Kinney Hannah C. , Haynes Robin L. , Xu Gang , Andiman Sarah E. , Folkerth Rebecca D. , Sleeper Lynn A. , Volpe Joseph J.
Published: August 2011

Objective:

The cellular basis of cognitive abnormalities in preterm infants with periventricular leukomalacia (PVL) is uncertain. One important possibility is that damage to white matter and subplate neurons that are critical to the formation of the cerebral cortex occurs in conjunction with oligodendrocyte and axonal injury in PVL. We tested the hypothesis that the overall density of neurons in the white matter and subplate region is significantly lower in PVL cases compared to non‐PVL controls.

Methods:

We used a computer‐based method for the determination of the density of microtubule‐associated protein 2‐immunolabeled neurons in the ventricular/subventricular region, periventricular white matter, central white matter, and subplate region in PVL cases and controls.

Results:

There were 5 subtypes of subcortical neurons: granular, unipolar, bipolar, inverted pyramidal, and multipolar. The neuronal density of the granular neurons in each of the 4 regions was 54 to 80% lower (p ≤ 0.01) in the PVL cases (n = 15) compared to controls adjusted for age and postmortem interval (n = 10). The overall densities of unipolar, bipolar, multipolar, and inverted pyramidal neurons did not differ significantly between the PVL cases and controls. No granular neurons expressed markers of neuronal and glial immaturity (Tuj1, doublecortin, or NG2).

Interpretation:

These data suggest that quantitative deficits in susceptible granular neurons occur in the white matter distant from periventricular foci, including the subplate region, in PVL, and may contribute to abnormal cortical formation and cognitive dysfunction in preterm survivors. ANN NEUROL 2012;
Deformational properties of filled rubber under quasistatic loading
Authors: Aniskevich Klara , Starkova Olesja , Aniskevich Andrey
Published: August 2011

To go ahead in understanding the nature of rubber reinforcement and evaluate the kinetics of filler clusters destruction during stretching of filled rubber, the styrene‐butadiene rubber both unfilled and filled with various contents of silica particles with and without surface treatment was tested under quasistatic loading up to failure. The Klueppel–Schramm model was used for description of strain softening, evaluation of both the rubber and filler network parameters as the functions of the filler volume content. It was found that an elastic modulus as a function of filler volume content follows Guth–Gold equation, confirming the hydrodynamic nature of the rubber reinforcement; the effectiveness factor depends on filler surface treatment. Hydrodynamic amplification factor increases with increase of filler volume content, its value depends on filler particles surface treatment. The decrease of hydrodynamic amplification factor during stretching correlates with the increase of viscoelastic strain. Taking into account the viscoelastic strain improves the description of the stress–strain response of filled rubber for loading–unloading process with the parameters obtained for active loading. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Synthesis and characterization of a novel charring agent and its application in intumescent flame retardant polypropylene system
Authors: Huang Jianqian , Zhang Yeqin , Yang Qi , Liao Xia , Li Guangxian
Published: August 2011

A novel halogen‐free charring agent bi(4‐methoxy‐1‐phospha‐2, 6, 7‐trioxabicyclo [2.2.2]‐octane‐1‐sulfide) phenylphosphate (BSPPO) was synthesized from phenylphosphonic dichloride (PPDC), and 4‐hydroxymethyl‐1‐phospha‐2, 6, 7‐trioxabicyclo[2.2.2]‐octane‐1‐sulfide (SPEPA) which was synthesized from pentaerythritol and thiophosphoryl chloride in this article. The structure of BSPPO and SPEPA was characterized by Fourier transform infrared (FTIR), 1H‐NMR, 13C‐NMR, and 31P‐NMR. Combined with ammonium polyphosphate (APP) and melamine pyrophosphate (MPP), the flame retardance and dripping resistance of BSPPO added in polypropylene (PP) were investigated. The fire performance of the flame retardant PP system was investigated by limiting oxygen index (LOI), vertical burning test (UL‐94), and cone calorimeter. The thermal stabilities of the composites were studied by thermogravimetric analysis (TGA). The flame retardance mechanism was investigated by FTIR and scanning electronic micrograph (SEM). The mechanical properties and water solubility were also investigated. The residue of BSPPO is 40.6% at 600°C, which indicates BSPPO has excellent charring ability. The char residue of the polypropylene intumescent flame retardant (PP‐IFR) system is 22% at 600°C, which suggests that the flame retardation synergy of APP, BSPPO, and MPP is good. With the optimum formulation, the LOI of the IFR‐PP system is 32.0, and the UL‐94 is V‐0 rating. The heat release rate (HRR), total heat release (THR), smoke production rate (SPR), total smoke production (TSP), and mass loss rate (MLR) of IFR‐PP with the optimum formulation decrease significantly comparing to pure PP from cone calorimeter analysis. The FTIR and SEM results indicate that the char properties and the char yield have direct effect on the flame retardance and antidripping behaviors. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Physicochemical and structural effects of electrolyte‐induced delamination on polyethylene teraphthalate‐coated steel plates
Authors: Zumelzu E. , Ortega C. , Rull F. , Cabezas C.
Published: August 2011

This research evaluated the in situ physicochemical changes and alterations occurring in an electrolytic chromium coated steel (ECCS), surface protected by polyethylene teraphthalate (PET) copolymer, after inducing a fracture on the coating in an acid acetic‐acetate medium. The delamination was characterized in the front of the failure by means of anodic and cathodic electrochemical mechanisms, and the resistance and degradation of the metal‐polymer composite's substrates were analyzed by means of Raman vibrational spectroscopy. The application of an electrochemical cell to generate in situ delamination, simulating the formation of pores or artificial defects, provided information on the activity inside the substrates of the PET‐coated ECCS composite as a result of the effect of the acetic acid. The anodic delamination mechanism is based on the diffusion of the electrolyte through the metal‐polymer interface and the pre‐existence of pores on the polymer layer. The cathodic delamination mechanism is based on the mechanical action of the gaseous hydrogen as a result of the reduction of H+. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Fabrication and characterization of silica/polypyrrole nanocomposites using silica sulfuric acid as templates
Authors: Wang Wenqin , Li Wenli , Chai Zhangling , Zhang Ruifeng
Published: August 2011

The sunflower‐like silica core‐polypyrrole (PPy) shell nanocomposites were prepared by using silica sulfuric acid as templates. The silica sulfuric acid was obtained by treating directly the silica nanoparticles with chlorosulfonic acid. The sulfonic groups (SO3H) on the surface of silica sulfuric acid not only offered the active sites for formation of polypyrrole particles but also acted as dopant agents in PPy. The nanostructures of sunflower‐like silica/PPy nanocomposites and hollow PPy capsules were investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The molecular structure and content of PPy were determined by Fourier transform infrared (FTIR) and thermal gravimetric analysis (TGA), respectively. The highest conductivity of nanocomposites is 2.4 S/cm. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Preparation, evaluation, and in vitro release study of O‐carboxymethyl chitosan nanoparticles loaded with gentamicin and salicylic acid
Authors: Ji Jingou , Hao Shilei , Dong Jin , Wu Danjun , Yang Bin , Xu Yi
Published: August 2011

To inhibit the ototoxicity of gentamicin (GM) and overcome the drawback related to chitosan (CS) nanoparticles preparation in acid solution, O‐carboxymethyl chitosan (O‐CMC) nanoparticles loaded with GM and salicylic acid (SA) were prepared by ionic cross‐linking method using calcium chloride as crosslinking agent. The Fourier transform infrared (FTIR) spectroscopy and X‐ray diffraction (XRD) were used to analyze the reaction of O‐CMC and crosslinking agent. The parameters of preparation of the compound nanoparticles including the concentration of O‐CMC, the mass ratio of O‐CMC to calcium chloride, and the feed ratio of SA to GM were investigated. The results showed that the obtained nanoparticles had a high zeta potential and drug‐loading capacity. The nanoparticles were characterized by a spherical morphology, with average size ranging from 148 to 345 nm and a narrow particle size distribution. In vitro release studies in phosphate buffer saline (pH 7.4) evidenced a burst release in the first 1 h, followed by a sustained release in the residual time. The release amount of SA and GM were approximately equal in 24 h, which indicated that the SA‐ and GM‐loaded O‐CMC nanoparticles are a promising carrier system for inhibiting the ototoxicity of GM. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Synthesis and characterization of linear low‐density polyethylene/sepiolite nanocomposites
Authors: Shafiq Muhammad , Yasin Tariq , Saeed Shaukat
Published: August 2011

Linear low‐density polyethylene (LLDPE)/sepiolite nanocomposites were prepared by melt blending using unmodified and silane‐modified sepiolite. Two methods were used to modify sepiolite: modification before heat mixing (ex situ) and modification during heat mixing (in situ). The X‐ray diffraction results showed that the position of the main peak of sepiolite remained unchanged during modification step. Infrared spectra showed new peaks confirming the development of new bonds in modified sepiolite and nanocomposites. SEM micrographs revealed the presence of sepiolite fibers embedded in polymer matrix. Thermogravimetric analysis showed that nanocomposites exhibited higher onset degradation temperature than LLDPE. In addition, in situ modified sepiolite nanocomposites exhibited higher thermal stability than ex situ modified sepiolite nanocomposites. The ultimate tensile strength and modulus of the nanocomposites were improved; whereas elongation at break was reduced. The higher crystallization temperature of some nanocomposite formulations revealed a heterogeneous nucleation effect of sepiolite. This can be exploited for the shortening of cycle time during processing. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Thermoreversible supramolecular polyurethanes with self‐complementary quadruple hydrogen‐bonded end groups
Authors: Zhu Bo , Feng Zhicheng , Zheng Zhen , Wang Xinling
Published: August 2011

In this article, a new type of strongly dimerizing 2‐ureido‐4‐[1H]‐pyrimidinone (UPy) with amine group is synthesized and then used as end‐group to prepare a novel series of supramolecular polyurethanes (PUs). The effects of strong and well‐defined hydrogen bonding on material properties of PUs are studied. In these PUs, the UPy groups consequently serve as thermoreversible associations or the “hard blocks” and the bi‐functional PU chains act as the “monomers.” This theoretical hypothesis is proved by the results of dynamic mechanical thermal analysis (DMTA) and rheological test. Thermal analysis shows that the strong hydrogen bonds from end groups restrict the formation of their microcrystalline domains. The supramolecular PUs exhibit good mechanical performance and their self‐assemble mechanism is discussed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Influence of nucleation on the brittle‐ductile transition temperature of impact‐resistant polypropylene copolymer: From the sight of phase morphology
Authors: Cheng Dong , Feng Jiachun , Yi Jianjun
Published: August 2011

Influence of α‐ and β‐nucleation on brittle‐ductile transition temperature (BDTT) of impact‐resistant polypropylene copolymers (IPCs) and their phase morphologies were comparatively investigated. Impact test showed that the BDTT of β‐nucleated IPC (β‐IPC) is ∼ 24°C lower than that of α‐nucleated one (α‐IPC). Structural characterizations including atomic force and scanning electron microscopic observations, small angle X‐ray scattering examination, and dynamical mechanical analysis revealed that dispersion of the ethylene‐propylene random copolymer‐rich (EPR‐rich) phase was finer in β‐IPC in comparison with that in α‐IPC. For the reason of looser lamellar arrangement, the portion of EPR‐rich components included in the interlamellar region of β‐IPC was higher than those of α‐IPC, which led to improved mobility for the amorphous polypropylene chains. It was proposed that the finer distribution of EPR‐rich phase, which might result from faster growth rate of the β‐crystal and looser lamellar arrangement of β‐spherulite, should be responsible for the improved impact‐resistance and lower BDTT in β‐IPC samples. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Electrospun magnetic fibrillar polyarylene ether nitriles nanocomposites reinforced with Fe‐phthalocyanine/Fe3O4 hybrid microspheres
Authors: Meng Fanbin , Zhan Yingqing , Lei Yajie , Zhao Rui , Zhong Jiachun , Liu Xiaobo
Published: August 2011

The electrospinning method has been employed to fabricate ultrafine nanofibers of high‐performance polyarylene ether nitriles (PEN) and PEN/Fe‐phthalocyanine/Fe3O4 nanocomposite fibers for the first time. Through optimizing the operational conditions, such as polymer concentration, applied electric voltage, federate, and distance between needle tip and collector, bead‐free and uniform fibers with smooth surfaces and certain diameters were obtained. The morphology of the PEN nanofibers is correlated to the corresponding rheological behaviors of the polymer solutions. The nanocomposite fibers showed a beads‐in‐string structures without agglomeration after introducing the Fe‐phthalocyanine/Fe3O4 hybrid microspheres in the polymer fibers. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) reveal an enhanced thermal stability of the nanocomposite fibers after introducing the hybrids. The glass transition temperature (Tg) of the nanocomposite fibers increases by 10°C with 30 wt % hybrid microspheres, compared with those of the pure PEN fibers. The magnetic properties of the PEN/Fe‐phthalocyanine/Fe3O4 nanocomposite fibers are different from those of the hybrid microspheres. The hybrid microspheres in the composite nanofibers become magnetically harder with a much larger coercivity than that of the fillers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Analysis of dynamically scheduled tile algorithms for dense linear algebra on multicore architectures
Authors: Haidar Azzam , Ltaief Hatem , YarKhan Asim , Dongarra Jack
Published: August 2011

The objective of this paper is to analyze the dynamic scheduling of dense linear algebra algorithms on shared‐memory, multicore architectures. Current numerical libraries (e.g., linear algebra package) show clear limitations on such emerging systems mainly because of their coarse granularity tasks. Thus, many numerical algorithms need to be redesigned to better fit the architectural design of the multicore platform. The parallel linear algebra for scalable multicore architectures library developed at the University of Tennessee tackles this challenge by using tile algorithms to achieve a finer task granularity. These tile algorithms can then be represented by directed acyclic graphs, where nodes are the tasks and edges are the dependencies between the tasks. The paramount key to achieve high performance is to implement a runtime environment to efficiently schedule the execution of the directed acyclic graph across the multicore platform. This paper studies the impact on the overall performance of some parameters, both at the level of the scheduler (e.g., window size and locality) and the algorithms (e.g., left‐looking and right‐looking variants). We conclude that some commonly accepted rules for dense linear algebra algorithms may need to be revisited. Copyright © 2011 John Wiley & Sons, Ltd.
Behavioural activation for the treatment of low‐income, African American adolescents with major depressive disorder: a case series
Authors: Jacob Maryann , L. Keeley Mary , Ritschel Lorie , Craighead W. Edward
Published: August 2011

Behavioural activation (BA) is a psychosocial treatment that has shown promise in the treatment of adults suffering from major depressive disorder (MDD). Recent studies have shown that BA may also be effective for treating depressed adolescents. There are no studies that have reported on the BA treatment of depressed and low‐income African American adolescents; thus, the current study reports on the effectiveness of a version of BA adapted for the treatment of African American adolescents who were diagnosed with MDD (n = 3). Participants were allowed to attend a maximum of 17 sessions of weekly psychotherapy. Based on results taken from structured interviews, two of the three participants no longer met criteria for MDD at the end of treatment, and the severity of clinician‐rated depressive symptoms and impairment decreased for all participants at post‐treatment assessment. Additionally, all participants and their caregivers reported satisfaction with treatment. Implications of these findings, study limitations and suggestions for future directions are discussed. Copyright © 2011 John Wiley & Sons, Ltd.

Key Practitioner Message

Behavioural activation is an emerging evidence‐based psychotherapeutic treatment for adolescent depression.

African American adolescents in particular can benefit behavioural activation.

Behavioural activation is an intervention that can be utilized in settings with limited resources.