bluuebunny/crossref_metadata_2025 huggingface dataset:
Cleavage of Transaldolase by Granzyme B Causes the Loss of Enzymatic Activity with Retention of Antigenicity for Multiple Sclerosis Patients
Authors: Niland Brian , Miklossy Gabriella , Banki Katalin , Biddison William E. , Casciola-Rosen Livia , Rosen Antony , Martinvalet Denis , Lieberman Judy , Perl Andras
Published: March 2010

Multiple sclerosis (MS) is an autoimmune demyelinating disease of the CNS resulting from a progressive loss of oligodendrocytes. Transaldolase (TAL) is expressed at selectively high levels in oligodendrocytes of the brain, and postmortem sections show concurrent loss of myelin basic protein and TAL from sites of demyelination. Infiltrating CD8+ CTLs are thought to play a key role in oligodendrocyte cell death. Cleavage by granzyme B (GrB) is predictive for autoantigenicity of self-proteins, thereby further implicating CTL-induced death in the initiation and propagation of autoimmunity. The precursor frequency and CTL activity of HLA-A2–restricted TAL 168–176–specific CD8+ T cells is increased in MS patients. In this paper, we show that TAL, but not myelin basic protein, is specifically cleaved by human GrB. The recognition site of GrB that resulted in the cleavage of a dominant TAL fragment was mapped to a VVAD motif at aa residue 27 by N-terminal sequencing and confirmed by site-directed mutagenesis. The major C-terminal GrB cleavage product, residues 28–337, had no enzymatic activity but retained the antigenicity of full-length TAL, effectively stimulating the proliferation and CTL activity of PBMCs and of CD8+ T cell lines from patients with MS. Sera of MS patients exhibited similar binding affinity to wild-type and GrB-cleaved TAL. Because GrB mediates the killing of target cells and cleavage by GrB is predictive of autoantigen status of self proteins, GrB-cleaved TAL-specific T cell-mediated cytotoxicity may contribute to the progressive destruction of oligodendrocytes in patients with MS.
Proinflammatory Cytokine IL-1β Stimulates IL-8 Synthesis in Mast Cells via a Leukotriene B4 Receptor 2-Linked Pathway, Contributing to Angiogenesis
Authors: Kim Geun-Young , Lee Jin-Wook , Ryu Ho-Cheol , Wei Jun-Dong , Seong Chu-Myong , Kim Jae-Hong
Published: March 2010

Recent studies have suggested that mast cells have critical roles in angiogenesis. However, the detailed mechanism by which mast cells contribute to angiogenesis is not yet clearly understood, especially in response to proinflammatory cytokines. In this study, we showed that the proinflammatory cytokine IL-1β induces the synthesis of IL-8, a potent angiogenic factor, in human mast cells via the leukotriene B4 receptor (BLT)2. We also characterized the BLT2 downstream signaling pathway and determined that BLT2-mediated IL-8 synthesis involves the upregulation of Nox1, a member of the NADPH oxidase family, Nox1-dependent reactive oxygen species generation and the subsequent activation of the redox-sensitive transcription factor NF-κB. For instance, knockdown of BLT2 and Nox1 with specific small interfering RNA, treatment with a specific BLT2 antagonist, LY255283, or treatment with a potential Nox inhibitor, diphenylene iodonium, suppressed IL-1β–induced IL-8 synthesis. We found that the conditioned media collected from IL-1β–treated human mast cell line HMC-1 had significantly enhanced angiogenic activity that could be dramatically attenuated by either small interfering RNA knockdown of BLT2 or treatment with neutralizing Ab to IL-8. Finally, the experiments were repeated using human primary cord blood-derived mast cells, and the results were clearly reproduced. Taken together, our results suggest that BLT2-Nox1-reactive oxygen species–dependent pathway plays a role in promoting the secretion of IL-8 from human mast cells in response to the proinflammatory cytokine IL-1β, thus contributing to angiogenesis.
Hypoxia-Mediated Expression of 5-Lipoxygenase–Activating Protein Involves HIF-1α and NF-κB and MicroRNAs 135a and 199a-5p
Authors: Gonsalves Caryn S. , Kalra Vijay K.
Published: March 2010

Hypoxia occurs in a number of pathological states, such as pulmonary, hematological, and cardiovascular disorders. In this study, we examined the molecular mechanism by which hypoxia contributes to increased leukotriene formation. Our studies showed hypoxia augmented the expression of 5-lipoxygenase activating protein (FLAP), a key enzyme in leukotriene formation, in both human pulmonary microvascular endothelial cells and a transformed human brain endothelial cell line. Hypoxia-induced FLAP mRNA expression involved activation of NADPH-oxidase, PI-3 kinase, mitogen-activated protein kinase, NF-κB, and hypoxia-inducible factor (HIF)-1α. Hypoxia-induced FLAP promoter activity was attenuated on mutation of hypoxia-response elements (HREs) and NF-κB binding motif in the FLAP promoter. Hypoxia also augmented binding of HIF-1α to HREs in FLAP promoter as demonstrated by EMSA with nuclear extracts. Furthermore, chromain immunoprecipitation analysis showed HIF-1α bound to HREs in native chromatin obtained from hypoxia-treated cells. Next, we examined the role of HIF-1α regulated microRNAs on FLAP expression. Our studies showed decreased expression of miR-135a and miR-199a-5p in response to hypoxia. However, overexpression of anti–miR-135a and anti–miR-199a-5p oligonucleotides led to a several fold increased FLAP mRNA and protein expression. These studies demonstrate for the first time that hypoxia-mediated FLAP expression is regulated by HREs and NF-κB site in its promoter, and negatively regulated by miR-135a and miR-199a-5p, which target the 3′-UTR of FLAP mRNA. An understanding of these regulatory pathways provides new avenues to ameliorate leukotriene formation and hence reactive airway disease, and inflammation in individuals who have sickle cell disease.
B Cells Are Required for Optimal CD4+ and CD8+ T Cell Tumor Immunity: Therapeutic B Cell Depletion Enhances B16 Melanoma Growth in Mice
Authors: DiLillo David J. , Yanaba Koichi , Tedder Thomas F.
Published: March 2010

B lymphocytes can both positively and negatively regulate cellular immune responses. Previous studies have demonstrated augmented T cell-mediated tumor immunity in genetically B cell-deficient mice, suggesting that therapeutic B cell depletion would enhance tumor immunity. To test this hypothesis and quantify B cell contributions to T cell-mediated anti-tumor immune responses, mature B cells were depleted from wild-type adult mice using CD20 mAb prior to syngeneic B16 melanoma tumor transfers. Remarkably, s.c. tumor volume and lung metastasis were increased 2-fold in B cell-depleted mice. Effector-memory and IFN-γ–or TNF-α–secreting CD4+ and CD8+ T cell induction was significantly impaired in B cell-depleted mice with tumors. Tumor Ag-specific CD8+ T cell proliferation was also impaired in tumor-bearing mice that lacked B cells. Thus, B cells were required for optimal T cell activation and cellular immunity in this in vivo nonlymphoid tumor model. Although B cells may not have direct effector roles in tumor immunity, impaired T cell activation, and enhanced tumor growth in the absence of B cells argue against previous proposals to augment tumor immunity through B cell depletion. Rather, targeting tumor Ags to B cells in addition to dendritic cells is likely to optimize tumor-directed vaccines and immunotherapies.
Neutrophil Transmigration Mediated by the Neutrophil-Specific Antigen CD177 Is Influenced by the Endothelial S536N Dimorphism of Platelet Endothelial Cell Adhesion Molecule-1
Authors: Bayat Behnaz , Werth Silke , Sachs Ulrich J. H. , Newman Debra K. , Newman Peter J. , Santoso Sentot
Published: March 2010

The human neutrophil-specific adhesion molecule CD177 (also known as the NB1 alloantigen) becomes upregulated on the cell surface in a number of inflammatory settings. We recently showed that CD177 functions as a novel heterophilic counterreceptor for the endothelial junctional protein PECAM-1 (CD31), an interaction that is mediated by membrane-proximal PECAM-1 IgD 6, which is known to harbor an S536N single nucleotide polymorphism of two major isoforms V98N536G643 and L98S536R643 and a yet-to-be-determined region on CD177. In vitro transendothelial migration experiments revealed that CD177+ neutrophils migrated significantly faster through HUVECs expressing the LSR, compared with the VNG, allelic variant of PECAM-1 and that this correlated with the decreased ability of anti-PECAM-1 Ab of ITIM tyrosine phosphorylation in HUVECs expressing the LSR allelic variant relative to the VNG allelic variant. Moreover, engagement of PECAM-1 with rCD177-Fc (to mimic heterophilic CD177 binding) suppressed Ab-induced tyrosine phosphorylation to a greater extent in cells expressing the LSR isoform compared with the VNG isoform, with a corresponding increased higher level of β-catenin phosphorylation. These data suggest that heterophilic PECAM-1/CD177 interactions affect the phosphorylation state of PECAM-1 and endothelial cell junctional integrity in such a way as to facilitate neutrophil transmigration in a previously unrecognized allele-specific manner.
Swiprosin-1/EFhd2 Controls B Cell Receptor Signaling through the Assembly of the B Cell Receptor, Syk, and Phospholipase C γ2 in Membrane Rafts
Authors: Kroczek Carmen , Lang Christiane , Brachs Sebastian , Grohmann Marcus , Dütting Sebastian , Schweizer Astrid , Nitschke Lars , Feller Stephan M. , Jäck Hans-Martin , Mielenz Dirk
Published: March 2010

Compartmentalization of the BCR in membrane rafts is important for its signaling capacity. Swiprosin-1/EFhd2 (Swip-1) is an EF-hand and coiled-coil–containing adaptor protein with predicted Src homology 3 (SH3) binding sites that we identified in membrane rafts. We showed previously that Swip-1 amplifies BCR-induced apoptosis; however, the mechanism of this amplification was unknown. To address this question, we overexpressed Swip-1 and found that Swip-1 amplified the BCR-induced calcium flux in WEHI231, B62.1, and Bal17 cells. Conversely, the BCR-elicited calcium flux was strongly attenuated in Swip-1–silenced WEHI231 cells, and this was due to a decreased calcium mobilization from intracellular stores. Complementation of Swip-1 expression in Swip-1–silenced WEHI231 cells restored the BCR-induced calcium flux and enhanced spleen tyrosine kinase (Syk) tyrosine phosphorylation and activity as well as SLP65/BLNK/BASH and phospholipase C γ2 (PLCγ2) tyrosine phosphorylation. Furthermore, Swip-1 induced the constitutive association of the BCR itself, Syk, and PLCγ2 with membrane rafts. Concomitantly, Swip-1 stabilized the association of BCR with tyrosine-phosphorylated proteins, specifically Syk and PLCγ2, and enhanced the constitutive interaction of Syk and PLCγ2 with Lyn. Interestingly, Swip-1 bound to the rSH3 domains of the Src kinases Lyn and Fgr, as well as to that of PLCγ. Deletion of the predicted SH3-binding region in Swip-1 diminished its association and that of Syk and PLCγ2 with membrane rafts, reduced its interaction with the SH3 domain of PLCγ, and diminished the BCR-induced calcium flux. Hence, Swip-1 provides a membrane scaffold that is required for the Syk-, SLP-65–, and PLCγ2-dependent BCR-induced calcium flux.
CXC Chemokine Ligand (CXCL) 9 and CXCL10 Are Antagonistic Costimulation Molecules during the Priming of Alloreactive T Cell Effectors
Authors: Rosenblum Joshua M. , Shimoda Naohiko , Schenk Austin D. , Zhang Howard , Kish Danielle D. , Keslar Karen , Farber Joshua M. , Fairchild Robert L.
Published: March 2010

Donor Ag-reactive CD4 and CD8 T cell production of IFN-γ is a principal effector mechanism promoting tissue injury during allograft rejection. The CXCR3-binding chemokines CXCL9 and CXCL10 recruit donor-reactive T cells to the allograft, but their role during the priming of donor-reactive T cells to effector function is unknown. Using a murine model of MHC-mismatched cardiac transplantation, we investigated the influence of CXCL9 and CXCL10 during donor-reactive T cell priming. In allograft recipient spleens, CXCL9 and CXCL10 were expressed as early as 24 h posttransplant and increased with similar kinetics, concurrently with CXCR3 expression on T cells. CXCL9, but not CXCL10, expression required NK cell production of IFN-γ. The absence of CXCL9 in donor allografts, recipients, or both significantly decreased the frequency of donor-reactive CD8 T cells producing IFN-γ and increased the frequency of donor-reactive CD8 T cells producing IL-17A. In contrast, the absence of CXCL10 increased the frequency of IFN-γ–producing CD8 T cells in a CXCL9-dependent manner. These data provide novel evidence that donor-reactive CD8 T cells use the CXCR3 chemokine axis as a costimulation pathway during priming to allografts where CXCL9 promotes the development of IFN-γ–producing CD8 T cells, and CXCL10 antagonizes this skewing.
The Actin-Bundling Proteinl-Plastin Dissociates CCR7 Proximal Signaling from CCR7-Induced Motility
Authors: Morley Sharon Celeste , Wang Chen , Lo Wan-Lin , Lio Chan-Wang J. , Zinselmeyer Bernd H. , Miller Mark J. , Brown Eric J. , Allen Paul M.
Published: March 2010

Chemokines promote lymphocyte motility by triggering F-actin rearrangements and inducing cellular polarization. Chemokines can also enhance cell–cell adhesion and costimulate T cells. In this study, we establish a requirement for the actin-bundling protein l-plastin (LPL) in CCR7- and sphingosine-1-phosphate–mediated T cell chemotaxis using LPL−/− mice. Disrupted motility of mature LPL−/− thymocytes manifested in vivo as diminished thymic egress. Two-photon microscopy of LPL−/− lymphocytes revealed reduced velocity and motility in lymph nodes. Defective migration resulted from defective cellular polarization following CCR7 ligation, as CCR7 did not polarize to the leading edge in chemokine-stimulated LPL−/− T cells. However, CCR7 signaling to F-actin polymerization and CCR7-mediated costimulation was intact in LPL−/− lymphocytes. The differential requirement for LPL in CCR7-induced cellular adhesion and CCR7-induced motility allowed assessment of the contribution of CCR7-mediated motility to positive selection of thymocytes and lineage commitment. Results suggest that normal motility is not required for CCR7 to function in positive selection and lineage commitment. We thus identify LPL as a molecule critical for CCR7-mediated motility but dispensable for early CCR7 signaling. The requirement for actin bundling by LPL for polarization reveals a novel mechanism of regulating actin dynamics during T cell motility.
Effects of MHC Class I Alleles on Licensing of Ly49A+ NK Cells
Authors: Jonsson A. Helena , Yang Liping , Kim Sungjin , Taffner Samantha M. , Yokoyama Wayne M.
Published: March 2010

NK cells are innate immune lymphocytes that can react to cells lacking self-MHC class I. However, NK cells that cannot engage self-MHC through an inhibitory receptor are resistant to stimulation through their activation receptors. To become licensed (i.e., functionally competent to be triggered through its activation receptors), an NK cell must engage host MHC class I via a MHC class I-specific inhibitory receptor, such as a member of the murine Ly49 family. To explore potential determinants of NK cell licensing on a single Ly49 receptor, we have investigated the relative licensing impacts of the b, d, k, q, r, and s H2 haplotypes on Ly49A+ NK cells. The results indicate that licensing is essentially analog but is saturated by moderate-binding MHC class I ligands. Interestingly, licensing exhibited a strong inverse correlation with a measure of cis engagement of Ly49A. Finally, licensing of Ly49A+ NK cells was found to be less sensitive to MHC class I engagement than Ly49A-mediated effector inhibition, suggesting that licensing establishes a margin of safety against NK cell autoreactivity.
Blockade of Programmed Death Ligand 1 Enhances the Therapeutic Efficacy of Combination Immunotherapy against Melanoma
Authors: Pilon-Thomas Shari , Mackay Amy , Vohra Nasreen , Mulé James J.
Published: March 2010

Inhibition of antitumor T cell responses can be mediated by the productive interaction between the programmed death-1 (PD-1) receptor on T cells and its ligand PD-L1. PD-L1 is highly expressed on both murine bone marrow-derived dendritic cells (DCs) and B16 melanoma. In this study, in vitro blockade of PD-L1 interaction on DCs led to enhanced IFN-γ production and cytotoxicity by Ag-specific T cells. In vivo, the systemic administration of anti–PD-L1 Ab plus melanoma peptide-pulsed DCs resulted in a higher number of melanoma peptide-specific CD8+ T cells, but this combination was insufficient to delay the growth of established B16 melanoma. Although the addition of 600 rad of total body irradiation delayed tumor growth, further adoptive transfer of Ag-specific CD8+ T cells was needed to achieve tumor regression and long-term survival of the treated mice. Lymphopenic mice treated with anti–PD-L1 Ab demonstrated increased activation and persistence of adoptively transferred T cells, including a higher number of CD8+ T cells infiltrating the tumor mass. Together, these studies support the blocking of PD-L1 signaling as a means to enhance combined immunotherapy approaches against melanoma.
Noncommutative geometry and compactifications of the moduli space of curves
Authors: Hamilton Alastair
Published: March 2010

In this paper we show that the homology of a certain natural compactification of the moduli space, introduced by Kontsevich in his study of Witten’s conjectures, can be described completely algebraically as the homology of a certain differential graded Lie algebra. This two-parameter family is constructed by using a Lie cobracket on the space of noncommutative 0-forms, a structure which corresponds to pinching simple closed curves on a Riemann surface, to deform the noncommutative symplectic geometry described by Kontsevich in his subsequent papers.
Prop profile of bi-Hamiltonian structures
Authors: Strohmayer Henrik
Published: March 2010

Recently S. A. Merkulov established a link between differential geometry and homological algebra by giving descriptions of several differential geometric structures in terms of minimal resolutions of props. In particular he described the prop profile of Poisson geometry. In this paper we define a prop such that representations of its minimal resolution in a vector space V are in a one-to-one correspondence with bi-Hamiltonian structures, i.e., pairs of compatible Poisson structures, on the formal manifold associated to V.
Locally constant $n$-operads as higher braided operads
Authors: Batanin Michael A.
Published: March 2010

We introduce a category of

locally constant

n

-operads

which can be considered as the category of higher braided operads. For

n = 1, 2, \infty

the homotopy category of locally constant

n

-operads is equivalent to the homotopy category of classical nonsymmetric, braided and symmetric operads, respectively.
Vibration Isolation of a GA Optimized Biomechanical Model of a Railway Passenger Using Magneto Rheological Damper Seat Suspension
Authors: Marzbanrad Javad , Rad Yousef Amiri , Afkar Amir
Published: March 2010

Driver tiredness during long term travel might result in many unwilling accidents. Hence, isolating the vibration transmitted to the driver plays a major role in keeping the driver restful and consequently having a safe trip. In this study, the transmitted vibration of a wagon suspension to a passenger model is isolated by a semi active control strategy using a magneto rheological (MR) damper. First, a revised linear lumped parameter biomechanical model of seated human body exposed to vertical vibrations is optimized. To this end, the parameters of the human body model, including mass, damper and stiffness coefficients are simultaneously optimized using genetic algorithm by employing a multi-objective function. Next, the optimized human body model is integrated on a nonlinear seat suspension model. This integrated model is excited by a sinusoidal frequency range as applicable to railway vehicles. The responses in time and frequency domains are derived. Finally, by using a MR damper instead of conventional dampers in the seat suspension, it is shown that the transmitted acceleration from the rail to the driver is reduced. Finally, a comparison of the performances of passive conventional dampers, semi-active MR dampers and active actuator assisted dampers is presented in detail.
Neural Networks Based Fatigue Life Prediction of Multi Walled Carbon Nano Tubes Doped E-Glass/Epoxy Laminates
Authors: Sai Prasanna Kumar J. V. , Soroja Devi M. , Raghava G. , Stanley A. Joseph
Published: March 2010

In recent years, carbon nano tubes and their applications have been the prime focus of research in the field of nanotechnology. In this paper, the fatigue life prediction of multi walled carbon nano tubes (MWCNT) doped E-Glass/Epoxy laminates is presented. Two different doping ratios of MWCNT (0.2% and 0.4%) are considered to demonstrate the improvement in fatigue life of the composite laminate. The fatigue tests are undertaken on an Instron 8802 universal testing machine using a uni-directional (UD) Glass/Epoxy laminate specimen fabricated as per the ASTM standard - ASTM D 3039. An artificial neural network (ANN) based approach with a back propagation algorithm is used to predict the fatigue life cycles. The proposed neural network is trained using the fatigue test data set. The predicted fatigue results from the ANN are in good agreement with the experimental results. The proposed approach can be utilised to predict the fatigue life of Glass/Epoxy laminates for varied MWCNT doping ratios.
Thermal Analysis of a Disc Brake Model Considering a Real Brake Pad Surface and Wear
Authors: Abu Bakar Abd. Rahim , Ouyang Huajiang , Khai Lee Chiing , Abdullah Mohd Shahrulizam
Published: March 2010

Vehicle braking system is considered as one of the most fundamental safety-critical systems in modern vehicles as its main purpose is to stop or decelerate the vehicle. The frictional heat generated during braking application can cause numerous negative effects on the brake assembly such as brake fade, premature wear, thermal cracks and disc thickness variation (DTV). In the past, surface roughness and wear at the pad interface have rarely been considered in studies of thermal analysis of a disc brake assembly using finite element method. This paper attempts to consider these two aspects to predict temperature distributions in a reduced disc brake model. First, two different brake pad interface models, i.e., smooth and rough surfaces are modelled and simulated. Temperature distributions in these two models are then compared. Next, the thermal analysis is performed with the effect of wear at three different braking applications.
Interference in eyewitness and earwitness recognition
Authors: Stevenage Sarah V , Howland Amy , Tippelt Anna
Published: March 2010

Face identification and voice identification were examined using a standard old/new recognition task in order to see whether seeing and hearing the target interfered with subsequent recognition. Participants studied either visual or audiovisual stimuli prior to a face recognition test, and studied either audio or audiovisual stimuli prior to a voice recognition test. Analysis of recognition performance revealed a greater ability to recognise faces than voices. More importantly, faces accompanying voices at study interfered with subsequent voice identification but voices accompanying faces at study did not interfere with subsequent face identification. These results are similar to those obtained in previous research using a lineup methodology, and are discussed with respect to the interference that can result when earwitnesses are also eyewitnesses. Copyright © 2010 John Wiley & Sons, Ltd.
The risks and benefits of long‐term use of hydroxyurea in sickle cell anemia: A 17.5 year follow‐up
Authors: Steinberg Martin H. , McCarthy William F. , Castro Oswaldo , Ballas Samir K. , Armstrong F. Danny , Smith Wally , Ataga Kenneth , Swerdlow Paul , Kutlar Abdullah , DeCastro Laura , Waclawiw Myron A.
Published: March 2010

A randomized, controlled clinical trial established the efficacy and safety of short‐term use of hydroxyurea in adult sickle cell anemia. To examine the risks and benefits of long‐term hydroxyurea usage, patients in this trial were followed for 17.5 years during which they could start or stop hydroxyurea. The purpose of this follow‐up was to search for adverse outcomes and estimate mortality. For each outcome and for mortality, exact 95% confidence intervals were calculated, or tests were conducted at α = 0.05 level (P‐value <0.05 for statistical significance). Although the death rate in the overall study cohort was high (43.1%; 4.4 per 100 person‐years), mortality was reduced in individuals with long‐term exposure to hydroxyurea. Survival curves demonstrated a significant reduction in deaths with long‐term exposure. Twenty‐four percent of deaths were due to pulmonary complications; 87.1% occurred in patients who never took hydroxyurea or took it for <5 years. Stroke, organ dysfunction, infection, and malignancy were similar in all groups. Our results, while no longer the product of a randomized study because of the ethical concerns of withholding an efficacious treatment, suggest that long‐term use of hydroxyurea is safe and might decrease mortality. Am. J. Hematol. 2010. © 2010 Wiley‐Liss, Inc.
Status of diurnal primate populations at the former settlement of a displaced village in Cameroon
Authors: Baya Lawrence , Storch Ilse
Published: March 2010

To understand whether or not primate populations recover in areas of abandoned human settlements, data are required that allow for site‐specific comparison over time. Here, we present baseline information on the presence/absence and relative abundance of primate species at the abandoned settlement of the Ekundukundu village, relocated out of the Korup National Park in 2000. Between July 2007 and March 2008, 62 km of transects was surveyed for sightings and calls of primates. All eight species of diurnal primates reported in the KNP were confirmed: Cercopithecus nictitans ludio, C. mona, C. erythrotis camerunensis, C. pogonias, Procolobus pennantii preussi, Cercocebus torquatus, Mandrillus leucophaeus leucophaeus, and Pan troglodytes vellerosus. At old Ekundukundu, C. nictitans accounted for 65% of all primate group sightings. Overall, sighting frequency of primates (0.55 groups/km) was not significantly different from other park sectors surveyed by a previous observer (J. Linder) in 2004–2005. The data reported here will be useful in the long‐term monitoring of primate populations in regenerating forest habitats of earlier human settlements. Am. J. Primatol. 72:645–652, 2010. © 2010 Wiley‐Liss, Inc.
Derivatives of biomacromolecules as stabilizers of aqueous alumina suspensions
Authors: Cerrutti Bianca M. , Lamas Juliana C. , De Britto Douglas , Campana Filho Sergio P. , Frollini Elisabete
Published: March 2010

The stabilization of alumina suspensions is key to the development of high‐performance materials for the ceramic industry, which has motivated extensive research into synthetic polymers used as stabilizers. In this study, mimosa tannin extract and a chitosan derivative, that is, macromolecules obtained from renewable resources, are shown to be promising to replace synthetic polymers, yielding less viscous suspensions with smaller particles and greater fluidity, that is, more homogeneous suspensions that may lead to better‐quality products. The functional groups of tannin present in mimosa extract and N,N,N‐trimethylchitosan (TMC) are capable of establishing interactions with the alumina surface, thus leading to repulsion between the particles mainly due to steric and electrosteric mechanisms, respectively. The stabilization of the suspension induced by either TMC or mimosa tannin was confirmed by a considerable decrease in viscosity and average particle size, in comparison with alumina suspensions without stabilizing agents. The viscosity/average particle size decreased by 49/84% and 52/87% for suspensions with TMC and mimosa tannin, respectively. In addition, the increase in the absolute zeta potential upon addition of either TMC or mimosa tannin extract, especially at high pHs, points to an increased stability of the suspension. The feasibility of using derivatives of macromolecules from renewable sources to stabilize aqueous alumina suspensions was therefore demonstrated. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Preparation of amidoximated bacterial cellulose and its adsorption mechanism for Cu2+ and Pb2+
Authors: Chen Shiyan , Shen Wei , Yu Feng , Hu Weili , Wang Huaping
Published: March 2010

Amidoximated bacterial cellulose (Am‐BC) was prepared through successive polymer analogous reactions of bacterial cellulose with acrylonitrile in an alkaline medium followed by reaction with aqueous hydroxylamine. It was used as an adsorbent to remove Cu2+ and Pb2+ from aqueous solutions. The adsorption behaviors of Cu2+ and Pb2+ onto Am‐BC were observed to be pH‐dependent. The maximum adsorption capacity of 84 and 67 mg g–1 was observed, respectively, for Cu2+ and Pb2+ at pH 5. Scanning electronic microscopy (SEM) indicated that the microporous network structure of Am‐BC was maintained even after the modifacation. The adsorption mechanisms for Cu2+ and Pb2+ onto Am‐BC were investigated by fourier transform infrared spectroscopy (FTIR), ζ potential measurement and X‐ray photoelectron spectroscopy (XPS). The results revealed that the mechanism for the adsorption of Cu2+ onto Am‐BC could be mainly described as between metal ions and nitrogen atom in the amidoxime groups or oxygen atom in the hydroxyl groups. However, in the adsorption process for Pb2+, precipitation played the important role along with electrostatic interactions, although chelation action also existed in the process accounted for the adsorption process. The regeneration of Am‐BC was studied by treatment with a strong complexing agent, ethylenediaminetetracetic acid (EDTA). © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Engineering properties of electron beam‐crosslinked ethylene methyl acrylate copolymer
Authors: Mongal Nilambar , Chakraborty Debabrata , Bhattacharyya Rupa , Kumar Chaki Tapan , Bhattacharya Pinaki
Published: March 2010

Effect of electron beam on mechanical, thermal, and morphological properties of ethylene methyl acrylate copolymer, grade Elvaloy 1335 has been investigated. The copolymer was subjected to varying doses of electron beam radiation with different proportion of the sensitizer trimethylolpropane trimethacrylate (TMPTMA). It was observed that with increase in electron beam dose, the physicomechanical properties of the crosslinked copolymer improve, reaches an optimum level and subsequently deteriorates. The thermal properties as envisaged from thermogravimetric analysis and differential scanning calorimetric studies revealed stability of the crosslinked irradiated samples over that of the unirradiated ones. The thermal stability was also found to attain the maximum at the same level of radiation and sensitizer. The morphological studies showed consistency with the mechanical properties. Based on the overall study, it may be concluded that ethylene methyl acrylate copolymer with 1 phr TMPTMA at 60 kGy radiation dose is the optimum condition within the range studied in this investigation. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Viscous behavior of PS, PP, and ABS in terms of temperature and pressure‐dependent hole fraction
Authors: Akdeniz Gülsüm , Yahsi Ugur , Tav Cumali
Published: March 2010

We have developed a zero‐shear viscous model in terms of temperature‐ and pressure‐dependent hole fraction computed from Simha‐Somcynsky Hole Theory. This model successfully interprets the viscosity data of PS, PP, and ABS as a function of hole fraction for a broad range of temperature and pressure. We have also introduced and discussed a new term: Viscoholibility; the derivative of logarithm of viscosity with respect to hole fraction. When the hole fraction takes highest available value, the viscoholibility approaches asymptotically to a constant value by which the viscosity changes linearly with the hole fraction. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
On the prospects of polyaniline and polyaniline/MWNT composites for possible pressure sensing applications
Authors: Varma S. J. , Jayalekshmi S.
Published: March 2010

This work highlights the prospects of applications of doped polyaniline (PANI) and Polyaniline–MultiWalled Carbon Nanotube (MWNT) composites with different dopants in pressure sensing devices. PANI and its nanocomposite samples in the form of pressed pellets show orders of change in electrical conductivity with applied pressure in the range 0–30 MPa, even for very small applied bias of a few milli‐volts. The percentage variation of electrical conductivity with applied pressure is strikingly large for PANI and its composite samples. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Dynamics of mechanical, acoustical, and electrical properties of epoxy‐amine compositions during cure
Authors: Rimlyand Vladimir I. , Starikova Vera N. , Bakhantsov Alexander V.
Published: March 2010

Dynamics of mechanical, acoustical, and electric properties is studied in the cure of three samples of polymeric compositions produced on the basis of epoxy oligomer with different content of the curing agent. The measurements were made in a parallel mode with an automated measuring complex. Variations in elastic modules, sound speed, attenuation coefficient, relaxation of the shear stress, electric resistance of the samples during the complete cure in the transition from a liquid into a glass state are considered. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Inter‐relationship between processing conditions and mechanical properties of blown film from different polypropylenes and high melt strength polypropylene blends
Authors: Auinger Thomas , Stadlbauer Manfred
Published: March 2010

The aim of this study is the improvement of process stability and film properties of various matrix polymers by the addition of long chain branched (LCB) polypropylene (PP) in the blown film process. Three commercially available PP grades were dry‐blended with two different high melt strength (HMS) PP grades with varying weight content in the range of 5, 10, and 20%. Maximum solid output was determined on a Hosokawa blown film line with a film thickness of 50 μm. Thickness was adjusted by proper relation between output and take‐up ratio (TUR). The blow‐up ratio (BUR) was varied from 1 : 2 to 1 : 3 and 1 : 4 in connection to the output rate and HMS‐PP content. Research showed an increase of the output due to the additon of HMS‐PP in various matrix polymers and different processing conditions. Influences on mechanical properties related to process parameters concerning stiffness and impact energy were found. Due to the addition of HMS‐PP in a heterophasic PP‐copolymer (PP‐I) the maximum solid output increases up to 50% as well as tensile properties were enhanced. Stiffness of the blown film is independent of the output and the BUR both in machine direction (MD) and transverse direction (TD). In contrast a reduction of the process stability and solid state properties were determined with homo‐PP (PP‐H) and random‐PP (PP‐R) mixtures. Decreasing impact energy of the heterophasic copolymer was determined with increasing HMS‐PP content. In comparison to the enhanced stiffness, toughness decreases which refers to a higher brittleness due to the addition of HMS‐PP. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Degradation behavior of hydrogel based on crosslinked poly(aspartic acid)
Authors: Yang Jun , Wang Fang , Tan Tianwei
Published: March 2010

The degradation behavior of hydrogel based on poly(aspartic acid) (PASP) which crosslinked by 1, 6‐hexamethylene diamine (HD) was studied in α‐chymotrypsin solution. The degradation behaviors of PASP under different crosslinking levels were evaluated as a function of biodegradation time by monitoring the changes of crosslinking density, molecular weight, rheological behavior, interior morphology, mass loss, and swelling ratio. It was found that the degradation behaviors relied heavily on the crosslinking density which calculated from the Flory‐Rehner equation. A pseudo first‐kinetic equation was proposed to model the mass loss behavior and the degradation rate constant was calculated under different crosslinking levels. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Degradation and antioxidant activity of κ‐carrageenans
Authors: Sun Tao , Tao Huina , Xie Jing , Zhang Shuo , Xu Xin
Published: March 2010

κ‐Carrageenan was degraded by an oxidative method involving hydrogen peroxide (H2O2). The molecular weight was measured by gel permeation chromatography. The effects of the concentration of H2O2 and initial κ‐carrageenan, pH value, and degradation time on the molecular weights of the degraded products were studied. The structural change of the degraded κ‐carrageenans was characterized by Fourier transform infrared spectroscopy and determination of the sulfate content. The antioxidant activity of the degraded κ‐carrageenans was evaluated as scavengers of superoxide anions and hydroxyl radicals by application of flow injection chemiluminescence technology. The values of the 50% inhibition concentration (IC50) against the superoxide anion of degraded κ‐carrageenans labeled A, B, C, and D (with weight‐average molecular weights of 3250, 5820, 15,080, and 209,000, respectively) were 2.65, 3.22, 6.66, and 8.13 mg/mL, respectively. As for hydroxyl radical scavenging, the IC50 values of κ‐carrageenans A, B, C, and D were 0.014, 0.049, 0.062, and 0.110 mg/mL, respectively. The results indicated that the κ‐carrageenans with lower molecular weights had better antioxidant activity. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Effect of organoclay in an immiscible poly(ethylene terephtalate) waste/poly(methyl methacrylate) blend
Authors: Kerboua N. , Cinausero N. , Sadoun T. , Lopez‐Cuesta J. M.
Published: March 2010

Blends of organically modified montmorillonite (OMMT) with poly(ethylene terephtalate) (PET) waste and poly(methyl methacrylate) (PMMA) were prepared by melt mixing. The morphology of PET/PMMA nanocomposites with different OMMT contents was characterized by transmission electron microscopy (TEM) and X‐ray diffraction (XRD). The nonisothermal crystallization temperatures of nanocomposites were also examined by DSC. TEM observations and XRD patterns revealed that silicate layers were intercalated and well dispersed in the blend. Nanocomposites displayed better mechanical properties when compared with the unfilled blend. DMA analyses also showed efficient mixing of the two immiscible polymers and changes in glass transition temperature with the presence of OMMT. DSC analysis showed an enhancement in crystallization rate of nanocomposites and a decrease in cristallinity. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Synthesis of biodegradable and biocompatible ABC triblock copolymers
Authors: He Xiaohua , Zhong Liang , Wang Kai , Luo Shufang , Xie Meiran
Published: March 2010

A facile approach is offered to synthesize well‐defined amphiphilic ABC triblock copolymers composed of poly(ethylene glycol) monomethyl ether (MPEO) as A block, poly(L‐lysine) (PLLys) as B block, and poly(ε‐caprolactone) (PCL) as C block by a combination of ring‐opening polymerization (ROP) and click reactions. The propargyl‐terminated poly(Z‐L‐lysine)‐block‐poly(ε‐caprolactone) (MPEO‐PzLLys‐PCL) diblock copolymers were synthesized via the ring‐opening polymerization of Nε‐carbobenzoxy‐L‐lysine N‐carboxyanhydride (Z‐L‐Lys NCA) in DMF at room temperature using propargyl amine as an initiator and the resulting amino‐terminated poly(Z‐L‐lysine) then used in situ as a macroinitiator for the polymerization of ε‐caprolactone in the presence of stannous octoate as a catalyst. The triblock copolymers poly(ethylene glycol) monomethyl ether –block‐poly(Z‐L‐lysine)‐block‐poly(ε‐caprolactone) (MPEO‐PzLLys‐PCL) were synthesized via the click reaction of the propargyl‐terminated PzLLys‐PCL and azido‐terminated poly(ethylene glycol) monomethyl ether (PEO‐N3) in the presence of CuBr and 1,1,4,7,7‐pentamethyldiethylenetriamine (PMDETA) catalyst system. After the removal of Z groups of L‐lysine units, amphiphilic and biocompatible ABC triblock copolymers MPEO‐PLLys‐PCL were obtained. The structural characteristics of these ABC triblock copolymers and corresponding precursors were characterized by NMR, IR, and GPC. These results showed the click reaction was highly effective. Therefore, a facile approach is offered to synthesize amphiphilic and biocompatible ABC triblock copolymers consisting of polyether, polypeptide and polyester. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Silk‐inspired polyurethane containing GlyAlaGlyAla tetrapeptide. I. Synthesis and primary structure
Authors: Liu Hongtao , Xu Weilin , Zhao Sanping , Huang Jingjing , Yang Hongjun , Wang Yunli , Ouyang Chenxi
Published: March 2010

Biomedical polyurethane (PU) and silk fibroin have similar molecular architecture in their primary and aggregate structure, both of which have imido bonds and microphase separation, and they have been employed as scaffold materials for biomedical applications. As the featured peptide sequence of silkworm silk protein, GlyAlaGlyAla (GAGA) tetrapeptide was synthesized by using traditional liquid‐phase peptide synthesis method with Boc‐protected alanine and glycine as starting materials, and was transformed to its derivative with two end‐amido groups. The derivative was incorporated into the backbone of the classical synthetic copolyurethane as a chain extender to form a silk‐inspired polyurethane. Elemental analysis showed the nitrogen content in the silk‐inspired PU was higher than that in the butanediol‐extended PU but lower than the theoretical value, indicating the chain extender containing GAGA was partially incorporated into the PU chain. The results from 1H‐nuclear magnetic resonance, Fourier transform infrared spectra, Raman scattering spectra and pyrolysis‐gas chromatography/mass spectrometry qualitatively identified the primary structure of the silk‐inspired polyurethane. This concept and strategy may allow the fabrication of a new class of thermoplastic polyurethane elastomer to mimic the structure and properties of silk fibers if in fiber form, which combines traditional synthetic polymer chains with peptide sequences. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Preparation of manganese oxide–polyethylene oxide hybrid nanofibers through in situ electrospinning
Authors: Madani Mohammad , Sharifi‐Sanjani Naser , Khoee Sepideh , Hasan‐Kaviar Ahmad , Kazemi Abbass
Published: March 2010

Manganese oxide nanoparticles–polyethylene oxide nanofibers as organic–inorganic hybrid were prepared via in situ electrospinning. Thus, electrospinning of polyethylene oxide solution with different manganese chloride concentration was carried out in gaseous ammonia atmosphere containing oxygen. The reaction of manganese chloride with ammonia produces manganese hydroxide, and then oxygen in the reaction media reacts with manganese hydroxide to yield manganese oxide. These two reactions occur during fiber formation. Transmission electron microscopy and scanning electron microscopy showed that manganese oxide (MnO2) nanoparticles were formed on the produced nanofibers of 100–600 nm in diameter. The existence of the formed MnO2 was also proved by X‐ray diffraction analysis, and it showed that the λ‐MnO2 nanoparticles were produced. Differential scanning calorimetry (DSC) analysis was used to determine the melting point and to calculate the crystallinity of the produced hybrid nanofibers. The DSC and thermogravimetric analysis results of the obtained nanofibers were compared with those of the nanofibers produced in electrospinning of pure polyethylene oxide solution. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Miscibility studies on a copolyester of bisphenol‐A with terephthalic and isophthalic acids/bisphenol‐A polycarbonate blends
Authors: Sakar Dolunay , Cakar Fatih , Cankurtaran Ozlem , Karaman Ferdane
Published: March 2010

The miscibility behavior of the blends of a copolyester of bisphenol‐A with terephthalic and isophthalic acids (PAr) and a bisphenol‐A polycarbonate (PC) was studied in dilute chloroform solutions at 25°C. The intrinsic viscosity and Huggins' parameter of the binary mixtures were determined from the intercept and slope of the linear straight line between specific viscosity and the overall polymer concentration at the studied compositions. From experimental results of the intrinsic viscosities of the mixtures, some miscibility parameters Δb, Δb′, (Δb)G, Δ[η], α, and β were obtained by applying the criteria proposed by the research groups Krigbaum and Wall, Catsiff and Hewett, Garcia et al., Sun et al. and Jiang and Han, respectively. The miscibility of mixtures was also studied by using differential scanning calorimetry and fourier transform infrared spectroscopy. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
An effort based analysis of the paradoxical effects of incentives on decision‐aided performance
Authors: Samuels Janet A. , Whitecotton Stacey M.
Published: March 2010

This study examines the effect of incentives on decision‐aided performance. In particular, the study provides further insight into whether, when, and how incentives affect task performance in the presence of decision aids by (1) replicating previous research showing the negative effects of incentives on performance; (2) investigating whether this effect generalizes to a more realistic scenario in which decision makers have access to additional contextual information not captured by the decision aid; and (3) applying an effort‐based framework to explain the link between incentives and performance. In contrast to the findings of prior research, our study shows that incentives do not necessarily decrease performance in the presence of decision aids. Rather, we demonstrate that the effect of incentives on decision‐aided performance depends on other contextual factors such as the absence or presence of additional contextual information. By further specifying the conditions under which incentives result in increases or decreases to decision‐aided task performance, our results have implications for both future research and the design of incentive systems in practice. Copyright © 2010 John Wiley & Sons, Ltd.