bluuebunny/crossref_metadata_2025 huggingface dataset:
Antigen-Induced Oligomerization of the B Cell Receptor Is an Early Target of FcγRIIB Inhibition
Authors: Liu Wanli , Won Sohn Hae , Tolar Pavel , Meckel Tobias , Pierce Susan K.
Published: January 2010

The FcγRIIB is a potent inhibitory coreceptor that blocks BCR signaling in response to immune complexes and, as such, plays a decisive role in regulating Ab responses. The recent application of high-resolution live cell imaging to B cell studies is providing new molecular details of the earliest events in the initiation BCR signaling that follow within seconds of Ag binding. In this study, we report that when colligated to the BCR through immune complexes, the FcγRIIB colocalizes with the BCR in microscopic clusters and blocks the earliest events that initiate BCR signaling, including the oligomerization of the BCR within these clusters, the active recruitment of BCRs to these clusters, and the resulting spreading and contraction response. Fluorescence resonance energy transfer analyses indicate that blocking these early events may not require molecular proximity of the cytoplasmic domains of the BCR and FcγRIIB, but relies on the rapid and sustained association of FcγRIIB with raft lipids in the membrane. These results may provide novel early targets for therapies aimed at regulating the FcγRIIB to control Ab responses in autoimmune disease.
miR-126 Is Downregulated in Cystic Fibrosis Airway Epithelial Cells and Regulates TOM1 Expression
Authors: Oglesby Irene K. , Bray Isabella M. , Chotirmall Sanjay H. , Stallings Raymond L. , O’Neill Shane J. , McElvaney Noel G. , Greene Catherine M.
Published: January 2010

Cystic fibrosis (CF) is one of the most common lethal genetic diseases in which the role of microRNAs has yet to be explored. Predicted to be regulated by miR-126, TOM1 (target of Myb1) has been shown to interact with Toll-interacting protein, forming a complex to regulate endosomal trafficking of ubiquitinated proteins. TOM1 has also been proposed as a negative regulator of IL-1β and TNF-α–induced signaling pathways. MiR-126 is highly expressed in the lung, and we now show for the first time differential expression of miR-126 in CF versus non-CF airway epithelial cells both in vitro and in vivo. MiR-126 downregulation in CF bronchial epithelial cells correlated with a significant upregulation of TOM1 mRNA, both in vitro and in vivo when compared with their non-CF counterparts. Introduction of synthetic pre–miR-126 inhibited luciferase activity in a reporter system containing the full length 3′-untranslated region of TOM1 and resulted in decreased TOM1 protein production in CF bronchial epithelial cells. Following stimulation with LPS or IL-1β, overexpression of TOM1 was found to downregulate NF-κB luciferase activity. Conversely, TOM1 knockdown resulted in a significant increase in NF-κB regulated IL-8 secretion. These data show that miR-126 is differentially regulated in CF versus non-CF airway epithelial cells and that TOM1 is a miR-126 target that may have an important role in regulating innate immune responses in the CF lung. To our knowledge, this study is the first to report of a role for TOM1 in the TLR2/4 signaling pathways and the first to describe microRNA involvement in CF.
Influenza Infection Leads to Increased Susceptibility to Subsequent Bacterial Superinfection by Impairing NK Cell Responses in the Lung
Authors: Small Cherrie-Lee , Shaler Christopher R. , McCormick Sarah , Jeyanathan Mangalakumari , Damjanovic Daniela , Brown Earl G. , Arck Petra , Jordana Manel , Kaushic Charu , Ashkar Ali A. , Xing Zhou
Published: January 2010

Influenza viral infection is well-known to predispose to subsequent bacterial superinfection in the lung but the mechanisms have remained poorly defined. We have established a murine model of heterologous infections by an H1N1 influenza virus and Staphylococcus aureus. We found that indeed prior influenza infection markedly increased the susceptibility of mice to secondary S. aureus superinfection. Severe sickness and heightened bacterial infection in flu and S. aureus dual-infected animals were associated with severe immunopathology in the lung. We further found that flu-experienced lungs had an impaired NK cell response in the airway to subsequent S. aureus bacterial infection. Thus, adoptive transfer of naive NK cells to the airway of prior flu-infected mice restored flu-impaired antibacterial host defense. We identified that TNF-α production of NK cells played an important role in NK cell-mediated antibacterial host defense as NK cells in flu-experienced lungs had reduced TNF-α expression and adoptive transfer of TNF-α–deficient NK cells to the airway of flu-infected mice failed to restore flu-impaired antibacterial host defense. Defected NK cell function was found to be an upstream mechanism of depressed antibacterial activities by alveolar macrophages as contrast to naive wild-type NK cells, the NK cells from flu-infected or TNF-α–deficient mice failed to enhance S. aureus phagocytosis by alveolar macrophages. Together, our study identifies the weakened NK cell response in the lung to be a novel critical mechanism for flu-mediated susceptibility to bacterial superinfection.
Mechanisms of Spatial and Temporal Development of Autoimmune Vitiligo in Tyrosinase-Specific TCR Transgenic Mice
Authors: Gregg Randal K. , Nichols Lisa , Chen Yiming , Lu Bao , Engelhard Victor H.
Published: January 2010

Generalized vitiligo is thought to have an autoimmune etiology and has been correlated with the presence of CD8 T cells specific for melanocyte differentiation Ag. However, limited animal models for the disease have hampered its understanding. Thus, we generated TCR transgenic mice that recognize an epitope of the melanocyte protein, tyrosinase. These animals develop vitiligo with strikingly similar characteristics to the human disease. Vitiligo develops temporally and spatially, with juvenile lesions forming bilaterally in head and facial areas, and only arising later in the body of adult animals. Vitiligo is entirely dependent on CD8 T cells, whereas CD4 T cells exert a negative regulatory effect. Importantly, CD8 T cells can be pervasively present in the skin in the steady state without inducing vitiligo in most areas. This points to developmental differences in melanocyte susceptibility and/or immunological effector mechanisms over time, or in different body locations. Disease is strongly dependent on both IFN-γ and CXCR3, whereas dependence on CCR5 is more limited, and both CCR4 and perforin are dispensable. Genetic ablation of CXCR3 or IFN-γ also resulted in scarce CD8 T cell infiltration into the skin. Our results identify unexpected complexity in vitiligo development and point toward possible therapeutic interventions.
Importance of Neonatal FcR in Regulating the Serum Half-Life of Therapeutic Proteins Containing the Fc Domain of Human IgG1: A Comparative Study of the Affinity of Monoclonal Antibodies and Fc-Fusion Proteins to Human Neonatal FcR
Authors: Suzuki Takuo , Ishii-Watabe Akiko , Tada Minoru , Kobayashi Tetsu , Kanayasu-Toyoda Toshie , Kawanishi Toru , Yamaguchi Teruhide
Published: January 2010

The neonatal FcR (FcRn) binds to the Fc domain of IgG at acidic pH in the endosome and protects IgG from degradation, thereby contributing to the long serum half-life of IgG. To date, more than 20 mAb products and 5 Fc-fusion protein products have received marketing authorization approval in the United States, the European Union, or Japan. Many of these therapeutic proteins have the Fc domain of human IgG1; however, the serum half-lives differ in each protein. To elucidate the role of FcRn in the pharmacokinetics of Fc domain-containing therapeutic proteins, we evaluated the affinity of the clinically used human, humanized, chimeric, or mouse mAbs and Fc-fusion proteins to recombinant human FcRn by surface plasmon resonance analysis. The affinities of these therapeutic proteins to FcRn were found to be closely correlated with the serum half-lives reported from clinical studies, suggesting the important role of FcRn in regulating their serum half-lives. The relatively short serum half-life of Fc-fusion proteins was thought to arise from the low affinity to FcRn. The existence of some mAbs having high affinity to FcRn and a short serum half-life, however, suggested the involvement of other critical factor(s) in determining the serum half-life of such Abs. We further investigated the reason for the relatively low affinity of Fc-fusion proteins to FcRn and suggested the possibility that the receptor domain of Fc-fusion protein influences the structural environment of the FcRn binding region but not of the FcγRI binding region of the Fc domain.
Children's memory for the times of events from the past years
Authors: Friedman William J. , Reese Elaine , Dai Xin
Published: January 2010

This study tested 8–12‐year‐olds' ability to localize in time parent‐reported events from four time intervals ranging from 6 months to 4 years ago. Memory for content was very accurate, and children's time estimates showed substantial agreement with the times provided by their parents. Accuracy of year judgments declined with retention interval, with the greatest change occurring between the 1–2‐year and 2–3‐year intervals. Season, month and time of day accuracy were much more stable over time. There were significant improvements with age in performance on measures of conventional time knowledge, and this performance was correlated with the accuracy of time estimates on the long time scales, controlling for age and general cognitive ability. Copyright © 2010 John Wiley & Sons, Ltd.
Video‐game training and naïve reasoning about object motion
Authors: Masson Michael E. J. , Bub Daniel N. , Lalonde Christopher E.
Published: January 2010

Naïve conceptions and associated misconceptions about object motion arise in part from limitations on perceptual experience. Certain commercial video games, such as Enigmo, provide interactive experience with realistic trajectories and practice at purposefully manipulating those trajectories. We tested the possibility that this experience could modify naïve intuitions about object motion, bringing them into closer alignment with Newtonian principles of mechanics. Fifty‐one middle‐school children were randomly assigned to play either Enigmo or a strategy game for six sessions. Only the Enigmo group improved their ability to generate realistic trajectories, but this improvement was limited to learning about the general parabolic shape of trajectories. After training, both groups received a 30‐minute tutorial on Newtonian principles which generated a much larger improvement in producing realistic trajectories than did game play. This improvement was of similar magnitude in both training groups, indicating that gaming experience provided no advantage in deriving benefits from direct instruction. Copyright © 2010 John Wiley & Sons, Ltd.
Testing the covariance matrix of the innovation sequence with sensor/actuator fault detection applications
Authors: Hajiyev Chingiz
Published: January 2010

Operative methods for testing the covariance matrix of the innovation sequence of the Kalman filter are proposed. The quadratic form of the random Wishart matrix is used in this process as a monitoring statistic, and the testing problem is reduced to the classical problem of minimization of a quadratic form on the unit sphere. As a result, two algorithms for testing the covariance matrix of the innovation sequence are proposed. In the first algorithm, the sum of all elements of the matrix is used as the scalar measure of the Wishart matrix that is being tested, while in the second algorithm, the largest eigenvalue of this matrix is used. In the simulations, the longitudinal and lateral dynamics of the F‐16 aircraft model are considered, and the detection procedure of sensor/actuator faults, which affect the covariance matrix of the innovation sequence, is examined. Some recommendations for the fastest detection of the fault are given. Copyright © 2010 John Wiley & Sons, Ltd.
Smart Hydrogels Co‐switched by Hydrogen Bonds and π–π Stacking for Continuously Regulated Controlled‐Release System
Authors: Li Fang , Zhu Yingchun , You Bo , Zhao Donghui , Ruan Qichao , Zeng Yi , Ding Chuanxian
Published: January 2010

A series of hydrogels with continuously regulatable release behavior can be achieved by incorporating hydrogen bonding and π–π stacking co‐switches in polymers. A poly(nitrophenyl methacrylate‐co‐methacrylic acid) hydrogel (NPMAAHG) for control over drug release is fabricated by copolymerizing 4‐nitrophenyl methacrylate and methacrylic acid using ethylene glycol dimethacrylate as a crosslinker. The carboxylic acid groups and nitrylphenyl groups form hydrogen bonds and π–π stacking interactions, respectively, which act as switches to control the release of guest molecules from the polymers. As revealed by the simulated gastrointestinal tract drug release experiments, the as‐synthesized NPMAAHG hydrogels can be regulated to release only 4.7% of drugs after 3 h in a simulated stomach and nearly 92.6% within 43 h in the whole digestive tract. The relation between the release kinetics and structures and the mechanism of the smart release control are analyzed in terms of diffusion exponent, swelling interface number, drug diffusion coefficient, and velocity of the swelling interface in detail. The results reveal that the release of guest molecules from the hydrogels can be continuously regulated for systemic administration by controlling the ratio of the hydrophilic hydrogen bonds and the hydrophobic π–π stacking switches.
Dual Stimuli‐Responsive Supramolecular Polypeptide‐Based Hydrogel and Reverse Micellar Hydrogel Mediated by Host–Guest Chemistry
Authors: Chen Yi , Pang Xiao‐Hui , Dong Chang‐Ming
Published: January 2010

Versatile strategies are currently being discovered for the fabrication of synthetic polypeptide‐based hybrid hydrogels, which have potential applications in polymer therapeutics and regenerative medicine. Herein, a new concept—the reverse micellar hydrogel—is introduced, and a versatile strategy is provided for fabricating supramolecular polypeptide‐based normal micellar hydrogel and reverse micellar hydrogels from the same polypeptide‐based copolymer via the cooperation of host–guest chemistry and hydrogen‐bonding interactions. The supramolecular hydrogels are thoroughly characterized, and a mechanism for their self‐assembly is proposed. These hydrogels can respond to dual stimuli—temperature and pH—and their mechanical and controlled drug‐release properties can be tuned by the copolymer topology and the polypeptide composition. The reverse micellar hydrogel can load 10% of the anticancer drug doxorubicin hydrochloride (DOX) and sustain DOX release for 45 days, indicating that it could be useful as an injectable drug delivery system.
Recent Progress in n‐Channel Organic Thin‐Film Transistors
Authors: Wen Yugeng , Liu Yunqi
Published: January 2010

Particular attention has been focused on n‐channel organic thin‐film transistors (OTFTs) during the last few years, and the potentially cost‐effective circuitry‐based applications in flexible electronics, such as flexible radiofrequency identity tags, smart labels, and simple displays, will benefit from this fast development. This article reviews recent progress in performance and molecular design of n‐channel semiconductors in the past five years, and limitations and practicable solutions for n‐channel OTFTs are dealt with from the viewpoint of OTFT constitution and geometry, molecular design, and thin‐film growth conditions. Strategy methodology is especially highlighted with an aim to investigate basic issues in this field.
Charge Transport Physics of Conjugated Polymer Field‐Effect Transistors
Authors: Sirringhaus Henning , Bird Matt , Zhao Ni
Published: January 2010

Field‐effect transistors based on conjugated polymers are being developed for large‐area electronic applications on flexible substrates, but they also provide a very useful tool to probe the charge transport physics of these complex materials. In this review we discuss recent progress in polymer semiconductor materials, which have brought the performance and mobility of polymer devices to levels comparable to that of small‐molecule organic semiconductors. These new materials have also enabled deeper insight into the charge transport physics of high‐mobility polymer semiconductors gained from experiments with high charge carrier concentration and better molecular‐scale understanding of the electronic structure at the semiconductor/dielectric interface.
Advanced Materials for Energy Storage
Authors: Liu Chang , Li Feng , Ma Lai‐Peng , Cheng Hui‐Ming
Published: January 2010

Popularization of portable electronics and electric vehicles worldwide stimulates the development of energy storage devices, such as batteries and supercapacitors, toward higher power density and energy density, which significantly depends upon the advancement of new materials used in these devices. Moreover, energy storage materials play a key role in efficient, clean, and versatile use of energy, and are crucial for the exploitation of renewable energy. Therefore, energy storage materials cover a wide range of materials and have been receiving intensive attention from research and development to industrialization. In this Review, firstly a general introduction is given to several typical energy storage systems, including thermal, mechanical, electromagnetic, hydrogen, and electrochemical energy storage. Then the current status of high‐performance hydrogen storage materials for on‐board applications and electrochemical energy storage materials for lithium‐ion batteries and supercapacitors is introduced in detail. The strategies for developing these advanced energy storage materials, including nanostructuring, nano‐/microcombination, hybridization, pore‐structure control, configuration design, surface modification, and composition optimization, are discussed. Finally, the future trends and prospects in the development of advanced energy storage materials are highlighted.
Halogen‐free flame‐retardant rigid polyurethane foams: Effect of alumina trihydrate and triphenylphosphate on the properties of polyurethane foams
Authors: Thirumal M. , Singha Nikhil K. , Khastgir Dipak , Manjunath B. S. , Naik Y. P.
Published: January 2010

Rigid polyurethane foam (PUF) filled with mixture of alumina trihydrate (ATH) and triphenyl phosphate (TPP) as fire retardant additive was prepared with water as a blowing agent. In this study, the ATH content was varied from 10 to 100 parts per hundred polyol by weight (php), and TPP was used at a higher loading of ATH (75 and 100 php) in a ratio of 1 : 5 to enhance the processing during PUF preparation. The effects of ATH on properties such as density, compressive strength, morphological, thermal conductivity, thermal stability, flame‐retardant (FR) behavior, and smoke characteristics were studied. The density and compressive strength of the ATH‐filled PUF decreased initially and then increased with further increase in ATH content. There was no significant change in the thermal stability with increasing ATH loading. We determined the FR properties of these foam samples by measuring the limiting oxygen index (LOI), smoke density, rate of burning, and char yield. The addition of ATH with TPP to PUF significantly decreased the flame‐spread rate and increased LOI. The addition of TPP resulted in easy processing and also improved FR characteristics of the foam. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Asymmetric cellulose acetate dialysis membranes: Synthesis, characterization, and performance
Authors: Saljoughi Ehsan , Amirilargani Mohammad , Mohammadi Toraj
Published: January 2010

Cellulose acetate (CA) is highly comparable to other synthetic polymer materials and is effective in the hemodialysis process. In this work, asymmetric CA membranes were synthesized with the phase‐inversion method. CA with a molecular weight of 52,000, poly(ethylene glycol) (PEG) with a molecular weight of 400, and 1‐methyl‐2‐pyrrolidone (NMP) were used as the polymer, additive, and solvent, respectively. The effects of the CA and PEG concentrations and coagulation bath temperature (CBT) on the morphology, pure water permeability (PWP), insulin/human serum albumin (HSA) transmission, and finally thermal and chemical stability of the prepared membranes were determined and investigated. In general, increasing the PEG concentration and CBT and reducing the CA concentration resulted in increased PWP and insulin/HSA transmission. Also, these variations facilitated the formation of macrovoids in the membrane sublayer. On the other hand, increasing the PEG and CA concentrations and reducing CBT resulted in increased thermal and chemical stability of the prepared membranes. Also, ratios of 15.5/10/74.5 and 17.5/10/72.5 (w/w) for the CA/PEG/NMP casting solutions and their immersion into coagulation baths with CBTs of 0 and 25°C, respectively, resulted in the preparation of membranes that had not only optimum sieving properties and higher PWP but also thermal and chemical stability better than that of conventional CA hemodialysis membranes. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Molecular dynamics study of TiO2/poly(acrylic acid‐co‐methyl methacrylate) and Fe3O4/polystyrene composite latex particles prepared by heterocoagulation
Authors: Luo Ying‐Da , Chen Jui‐Hung , Huang Ching‐I , Chiu Wen‐Yen
Published: January 2010

All‐atom molecular dynamics simulations were used to study the morphology of polymer/inorganic composite particles prepared by heterocoagulation. The results were also compared to those of our previous study of the preparation of TiO2/poly(acrylic acid‐co‐methyl methacrylate) and Fe3O4/polystyrene composite particles. In the simulation system, polymer or inorganic particles were simulated by surface‐charge‐modified C60 or Na atoms. Through a combination of analysis of the radial distribution functions of charged atoms and snapshots of the equilibrated structure, three kinds of particle distributions were observed under different conditions. When the polymer and inorganic particles had opposite surface charges and their sizes were very different, the composite morphology showed a core–shell structure with small particles adsorbed onto the surfaces of large particles. Furthermore, when the polymer and inorganic particles had opposite surface charges but comparable sizes, the polymer and inorganic particles aggregated domain by domain. Finally, when the polymer and inorganic particles were endowed with the same surface charge, the distribution of these two types of particles was homogeneous, regardless of their size difference. The simulation results were in agreement with the experimental results. The electrostatic interaction and the size of the particles dominated the final morphology of the composite particles when the heterocoagulation method was used. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Properties of compatibilized polylactide blend films with gelatinized corn and tapioca starches
Authors: Phetwarotai Worasak , Potiyaraj Pranut , Aht‐Ong Duangdao
Published: January 2010

Blend films containing two types of starch, various amounts of methylenediphenyl diisocyanate (MDI), and polylactide were prepared. The effects of MDI level and starch type on the tensile, thermal, and morphological properties of these films were investigated. The MDI amount was varied from 0 to 10 wt % on the basis of gelatinized starch (GS) content, whereas two types of starch (corn and tapioca) were added as fillers. In this study, the blend films were hot‐mixed at 180°C by an internal batch mixer and then compression‐molded to form test specimens. The results show that the addition of MDI as a compatibilizer led to an increase in the tensile properties compared with the uncompatibilized films. Furthermore, the thermal properties indicated some improving interfacial adhesion between the two phases, as evidenced by the morphological results. These behaviors were observed in the blends with both gelatinized tapioca starch and gelatinized corn starch. The different types of starch had no effect on the glass‐transition and melting‐temperature shifts, including water absorption of the blend films. On the other hand, the mechanical properties of the blends with gelatinized corn starch were higher than those of the others. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Anisotropic in vitro vessel model using poly(vinyl alcohol) hydro gel and mesh material
Authors: Liu Lei , Kosukegawa Hiroyuki , Ohta Makoto , Hayase Toshiyuki
Published: January 2010

In the present study, the authors fabricated straight multilayer hybrid tubular in vitro vessel models (inner diameter Din = 10 mm; thickness T = 4 mm) composed of poly(vinyl alcohol) hydrogel (PVA‐H) and anisotropic mesh materials. The authors performed tensile, stress‐relaxation and cyclic‐tensile tests using axial and circumferential test pieces as well as pressure‐diameter (P‐D) tests using tubular test piece. In the tensile and stress‐relaxation tests, the anisotropic and nonlinear mechanical properties and hysteresis characteristic of the in vitro models were confirmed. The in vitro models also showed behavior qualitatively similar to that of native arteries in cycle‐tensile and P‐D tests. These results demonstrate that the mechanical properties of native vessels can be duplicated in an in vitro model by controlling the components of the mesh material, the orientation of elastic fibers in the mesh material, and the concentration and thickness of PVA‐H layers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Architecture of prototype copolymer brushes composed of alternating structure and intramolecular phase separation of side chains in solution
Authors: Ishizu Koji , Furuta Yuya , Nojima Shuichi , Uchida Satoshi
Published: January 2010

Atom transfer radical polymerization (ATRP) was applied to the synthesis of prototype copolymer brushes composed polystyrene/poly(t‐butyl methacrylate) (PS/PBMA) alternating structure. Dilute solution properties of prototype copolymer brush were investigated by static and dynamic light scattering (SLS and DLS) in tetrahydrofuran (THF). As a result, such prototype copolymer brush composed of short aspect ratio formed a star‐like single molecule in THF. To discuss the intramolecular phase separation of PS/PBMA brushes in solution, we determined the radius of gyration (Rg) and cross‐sectional radius of gyration (Rg,c) of prototype copolymer brush by small‐angle X‐ray scattering (SAXS) using Guinier's plots in THF and styrene. We used styrene as solvent to cancel each other out with the electron density of PS side chains. Both Rg and Rg,c obtained in styrene decreased drastically compared with those obtained in THF. These results indicated strongly that PS and PBMA side chains of prototype brushes formed intramolecular phase separation even in good solvent. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Rheological behavior of polymer–clay nanocomposite hydrogels: Effect of nanoscale interactions
Authors: Abdurrahmanoglu Suzan , Okay Oguz
Published: January 2010

This research highlights different viscoelastic responses of polymer–clay nanocomposite hydrogels depending on the type of the monomer used in their preparation. Polymerization reactions of N,N‐dimethylacrylamide (DMA), N‐isopropylacrylamide (NIPA), and acrylamide (AAm) in aqueous clay (Laponite) dispersions have been investigated by rheometry using oscillatory deformation tests. The gelation profile of AAm polymerization obeys typical gelation kinetics, while a reverse behavior was observed during the DMA or NIPA polymerizations. In the latter cases, after an abrupt increase in elastic and viscous moduli at the start of the reaction, they both decrease continuously during the whole course of the gelation process. Creep‐recovery tests performed on the final hydrogels indicate that the time‐dependent viscoelastic response of the gels derived from AAm is distinctly different from the other gels. The retardation time of AAm gel is about twice that of DMA or NIPA gels indicating higher mobility of the crosslink zones in the former gel. As a consequence, a larger amount of energy is dissipated during the deformation of nanocomposite hydrogels based on AAm. Different extent of interactions between the clay particles and the monomers explains the results of observations. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Reactions of low molecular weight highly functionalized maleic anhydride grafted polyethylene with polyetherdiamines
Authors: Hameed Tayyab , Potter David K. , Takacs Elizabeth
Published: January 2010

Reaction between low molecular weight highly functionalized maleic anhydride grafted polyethylene and several diamines were carried out using xylene as a reaction media. The influence of varying the amine to maleic anhydride (NH2/MAH) molar ratio and chain length of diamine on reaction was investigated. It was shown that the reactions of these materials cannot be followed by FTIR measurements alone. In these examples, colorimetric titrations were used to assess residual acid/anhydride content that was not detected by FTIR. The reaction between anhydride and amine was observed to be fast. The degree of reaction and crosslinking in the reactor was observed to depend on the concentration of the reaction mixture and the NH2/MAH molar ratio. In some cases, a gelatinous insoluble mass was produced in the reactor and this material was not easily processed for further characterization. All soluble reaction products obtained were observed to be thermoplastic and could be melt processed at elevated temperatures. However, further reaction and crosslinking of these materials occurred during processing to produce thermosets, as demonstrated by rheological measurements and sintering experiments. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
A study of critical processing technologies of liquid crystal polymer printed circuit board for high speed application
Authors: Yung K. C. , Liem H. , Choy H. , Yue T. M.
Published: January 2010

Recent demand for high‐frequency and high‐speed signal transmission over GHz is driving the printed circuit board (PCB) industry towards a more advanced material‐based era. To meet this market demand, liquid crystal polymer (LCP) has been suggested for its predominant material characteristics, such as high temperature resistance, low moisture absorption and excellent dimensional stability. However, former experimental and theoretical studies on the fabrication technology for processing the LCP PCB at different treatment conditions are lacking. This article thus evaluates the recent development of LCP PCB process technology. Different process approaches involving in lamination, drilling, desmearing, and metallization are proposed and compared, and associated reliability testing is addressed. Experimental results are shown to demonstrate the efficacy of the proposed approach for developing the process technology of LCP PCB. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Measurement of the solubility and diffusivity of blowing agents in polystyrene
Authors: Perez‐Blanco Marcos , Hammons Jeffrey R. , Danner Ronald P.
Published: January 2010

The solubility and diffusivity of several gases in polystyrene (PS) and styrene acrylonitrile copolymer (SAN) were studied with the pressure decay method. Data were collected for carbon dioxide, isobutane, and 1,1,1,2‐tetrafluoroethane (R‐134a) in PS and for R‐134a in SAN. The temperature range was between 30 and 200°C, and the gas pressures ranged from approximately 0.2 to 8.2 MPa. To cover these ranges, both the absolute and differential pressure decay methods were required. Henry's law was found to adequately represent all the gas solubilities. Isobutane and R‐134a were found to have a plasticizing effect on PS and SAN; that is, the diffusivity increased significantly as the pressure (and mass uptake) increased. CO2 in PS had the highest diffusivity and lowest solubility and did not affect the diffusivity in PS over the pressure range studied. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Synthesis and characterization of fluorine‐containing liquid crystalline polysiloxanes bearing cholesteryl cinnamate mesogens and trifluoromethyl‐substituted mesogens
Authors: Meng Fan‐Bao , Wang Zheng‐Yan , Chai Guo‐Wei , Wang Hong‐Guang , Chen Ying , Zhang Bao‐Yan
Published: January 2010

Several novel side‐chain liquid crystalline (LC) polysiloxanes bearing cholesteryl cinnamate mesogens and trifluoromethyl‐substituted mesogens were synthesized by a one‐step hydrosilylation reaction with poly(methylhydrogeno)siloxane, a cholesteric LC monomer cholesteryl 3‐(4‐allyloxy‐phenyl)‐acryloate and a fluoro‐containing LC monomer 4‐[2‐(3‐trifluoromethyl‐phenoxy)‐acetoxy]‐phenyl 4‐allyloxy‐benzoate. The chemical structures and LC properties of the monomers and polymers were characterized by use of various experimental techniques, such as FTIR, 1H‐NMR, 13C‐NMR, TGA, DSC, POM, and XRD. The temperatures at which 5% weight loss occurred were greater than 300°C for all the polymers, and the residue weight near 600°C increased slightly with increase of the trifluoromethyl‐substituted mesogens in the fluorinated polymer systems. The samples containing mainly cholesteryl cinnamate mesogens showed chiral nematic phase when they were heated and cooled, but the samples containing more trifluoromethyl‐substituted mesogens exhibited chiral smectic A mesophase. The glass transition temperature of the series of polymers increased slightly with increase of trifluoromethyl‐substituted mesogens in the polymer systems, but mesophase–isotropic phase transition temperature did not change greatly. In XRD curves, the intensity of sharp reflections at low angle increased with increase of trifluoromethyl‐substituted mesogens in the fluorinated polymers systems, indicating that the smectic order derived from trifluoromethyl‐substituted mesogens should be strengthened. These results should be due to the fluorophobic effect between trifluoromethyl‐substituted mesogens and the polymer matrix. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Structure and properties of polyethylene ionomer based nanocomposites
Authors: Santamaría Pablo , Eguiazábal Jose I. , Nazábal Jon
Published: January 2010

Li and Zn ionomers of poly(ethylene‐co‐methacrylic acid) were modified by two organically modified montmorillonites by melt mixing. In the nanocomposites (NCs), the increase in the loss tangent main peak temperature indicated a reduction in the mobility of the long‐chain segments containing neutralized acid groups. The stack compaction observed by wide‐angle X‐ray scattering and transmission electron microscopy in the Cloisite 30B based NCs was attributed to the partial degradation of the surfactant and to the irreversible character of the ion‐exchange process of the ammonium cation of the surfactant with the Li cation. The considerable dispersion that occurred in the poly(ethylene‐co‐methacrylic acid) zinc salt (PEMA–Zn)/Cloisite 20A (20A) NCs was attributed to the high volume of the surfactant, which reduced undesired interactions between the inorganic clay surface and the ionomer. The ductile nature of the matrix remained in all of the NCs, and the increase in the modulus of elasticity of the PEMA–Zn/20A NCs reached a value five times greater than that of the PEMA–Zn matrix. The results suggest that this ionomer is suitable for use both as a matrix for 20A NCs and as a compatibilizer of polyolefin‐based NCs with 20A. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Macroscopic N‐halamine biocidal polymeric beads
Authors: Ahmed Abd El‐Shafey I. , Hay John N. , Bushell Michael E. , Wardell John N. , Cavalli Gabriel
Published: January 2010

The particle size of N‐halamine biocidal polymers was methodically modified forming beads of different sizes by blending water‐insoluble N‐halamine polyurethane with sodium alginate as the matrix and loading heterocyclic rings onto modified silica gels. The biological activity of the prepared beads and halogenated modified silica derivatives was evaluated against examples of Gram‐positive (Staphylococcus aureus) and Gram‐negative (Escherichia coli) bacteria. The recycling possibilities and the optimum preparation conditions of the blended beads were investigated; blending prehalogenated polyurethane (5%, w/v) with sodium alginate (3%, w/v) followed by crosslinking with CaCl2 (10%, w/v) at 40°C are the optimum preparation conditions for the alginate beads. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Fabrication of water‐stable electrospun polyacrylic acid‐based nanofibrous mats for removal of copper (II) ions in aqueous solution
Authors: Xiao Shili , Shen Mingwu , Ma Hui , Guo Rui , Zhu Meifang , Wang Shanyuan , Shi Xiangyang
Published: January 2010

Polyacrylic acid (PAA) is an important polymer material for metal ion complexation and for nanocomposite materials syntheses. Generating ultrafine, uniform, and stable PAA nanofibers is of great scientific and technological interest for various applications. In this study, we systematically investigated the influence of processing parameters on the morphology and stability of the electrospun ultrafine PAA nanofibers. We show that a higher concentration (up to 25 wt %) favored the formation of uniform PAA nanofibers, whereas at the concentration of 10 wt %, only bead structures were produced. Increasing the applied voltage (up to 22.5 kV) resulted in more uniform PAA nanofibers. In addition, longer collection distance (20 cm) was beneficial for the evaporation of solvent and for decreasing the adhesion between nanofibers, thus leading to the nanofibrous mats with high porosity. Finally, the PAA nanofibers could be rendered water insoluble by heating the electrospun composite PAA/polyvinyl alcohol (PVA) nanofibers at 145°C for 30 min. The resulting nanofibrous mats exhibited excellent performance to remove Cu(II) ions in aqueous solution. The formed nanofibers may find various applications in ultrafiltration, separation, and environmental sciences. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Photoactive antimicrobial PVA hydrogel prepared by freeze‐thawing process for wound dressing
Authors: Hong Kyung Hwa , Sun Gang
Published: January 2010

A freeze‐thawing process was employed to produce both rose bengal (RB)/polyvinyl alcohol (PVA) and benzophenone (BP)/PVA hydrogels, respectively. Results indicated that only RB incorporated PVA (RB/PVA) could form hydrogel after undergoing three cycles of freeze‐thawing process; One of the cycles should be conducted by freezing at −15°C ± 3°C for 18 h followed by thawing at 25°C for 6 h. The structural features and functional properties of the RB/PVA hydrogel were investigated by FTIR, XRD, SEM evaluations, and photo‐induced antimicrobial functions were examined as well. Release of RB from the RB/PVA hydrogel was examined by UV‐Vis spectroscopy. The freeze‐thawed RB/PVA hydrogel showed antimicrobial abilities against both E. coli and S. aureus under the exposure to fluorescence light as well as UVA (365 nm) light. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Formation and structure of poly(methyl methacrylate) gels containing triphenyl vinyl silane
Authors: Naghash Hamid Javaherian
Published: January 2010

A series of Poly(methyl methacrylate) gels (PMMA) were prepared for making optical lenses by solution free radical crosslinking copolymerization of 2,2,2,‐trifluoroethyl methacrylate (TFEMA), methyl methacrylate (MMA), ethylene glycol dimethacrylate (EGDM), and triphenyl vinyl silane (TPVS) comonomer systems. They were then studied in toluene at a total monomer concentration of 5 molL−1and 70°C. The conversion of monomer, volume swelling ratio, weight fraction, and gel point were measured as a function of the TPVS concentration, temperature, and chain transfer agents up to the onset of macrogelation. Structural characteristics of the gels were examined by using equilibrium swelling in toluene, gel fraction, and Fourier‐transform infrared (FTIR) analysis. The morphology of the copolymers was also investigated by Scanning electron microscopy (SEM). The dilution of the monomer mixture resulted in an increase in the gel point and swelling degree and a decrease in the percentage of conversion and gel fraction. Finally, TPVS is a compatible vinyl type silicone comonomer for this system. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Effects of acute or chronic exposure to dietary organic anions on secretion of methotrexate and salicylate by Malpighian tubules ofDrosophila melanogasterlarvae
Authors: Chahine Sarah , O'Donnell Michael J.
Published: January 2010

The effects of dietary exposure to organic anions on the physiology of isolated Malpighian tubules and on tubule gene expression were examined using larvae ofDrosophila melanogaster. Acute (24 h) or chronic (7 d) exposure to type I organic anions (fluorescein or salicylate) was associated with increased fluid secretion rates and increased fluxes of both salicylate and the type II organic anion methotrexate. By contrast, chronic exposure to dietary methotrexate was associated with increased fluid secretion rate and increased flux of methotrexate, but not salicylate. Exposure to methotrexate in the diet resulted in increases in the expression of a multidrug efflux transporter gene (MET; CG30344) in the Malpighian tubules. There were also increases in expression of genes for either aDrosophilamultidrug resistance–associated protein (dMRP; CG6214) or an organic anion transporting polypeptide (OATP; CG3380), depending on the concentration of methotrexate in the diet. Exposure to salicylate in the diet was associated with an increase in expression of dMRP and with decreases of MET and OATP. Exposure to dietary salicylate or methotrexate was also associated with different patterns of expression of heat shock protein genes. The results suggest that exposure to specific type I or type II organic anions has multiple effects and results not only in increased organic anion transport but also in increased rates of inorganic ion transport, which drives osmotically‐obliged fluid secretion. Increased fluid secretion may enhance secretion of organic anions by eliminating diffusive backflux from the tubule lumen to the hemolymph. © 2010 Wiley Periodicals, Inc.
Expression profiling of novel bacteria‐induced genes from the silkworm, Bombyx mori
Authors: Tanaka Hiromitsu , Suzuki Noriko , Nakajima Yoshiro , Sato Masaaki , Sagisaka Aki , Fujita Kosuke , Ishibashi Jun , Imanishi Shigeo , Mita Kazuei , Yamakawa Minoru
Published: January 2010

In this study, we have newly identified three bacteria‐induced genes from the silkworm Bombyx mori by quantitative reverse transcriptase‐polymerase chain reaction. One of these, eukaryotic initiation factor 4E‐1 (eIF4E‐1), is assumed to encode an eIF4E family, which plays a role in the initiation of translation as a mRNA cap‐binding protein. The second gene is BmFOXG1, belonging to a family of forkhead transcription factors, FOXG1. The third gene is MBF2‐related (MBF2‐R) whose product has high homology to a co‐activator protein MBF2 from B. mori. Although BmFOXG1 was up‐regulated in the fat body in response to three kinds of bacteria, Escherichia coli, Staphylococcus aureus, and Bacillus subtilis, eIF4E‐1 and MBF2‐R were up‐regulated by E. coli and B. subtilis, but not S. aureus, suggesting that bacteria possessing meso‐diaminopimelic acid‐containing peptidoglycan but not lysine‐containing peptidoglycan activate eIF4E‐1 and MBF2‐R, probably through a conserved immune deficiency pathway. We further profiled the expression of three genes in different tissues and a silkworm cell line, NIAS‐Bm‐aff3, in response to bacteria, and at different times after bacterial challenge in the fat body. © 2010 Wiley Periodicals, Inc.
Synthesis of α‐ and β‐Pyran Naphthoquinones as a New Class of Antitubercular Agents
Authors: Ferreira Sabrina B. , de Carvalho da Silva Fernando , Bezerra Flávio A. F. M. , Lourenço Maria C. S. , Kaiser Carlos R. , Pinto Angelo C. , Ferreira Vitor F.
Published: January 2010

A series of α‐ and β‐pyran naphthoquinones (lapachones) have been synthesized and evaluated for their in‐vitro antibacterial activity against Mycobacterium tuberculosis strain H37Rv (ATCC 27294) using the Alamar‐Blue susceptibility test; the activity was expressed as the minimum inhibitory concentration (MIC) in μg/mL. The synthetic methodology consisted of the formation of methylene and aryl o‐quinone methides (o‐QMs) generated by Knoevenagel condensation of 2‐hydroxy‐1,4‐naphthoquinone with formaldehyde and arylaldehydes. These o‐QMs then undergo facile hetero Diels–Alder reactions with dienophiles in aqueous ethanol media. Some naphthoquinones exhibited inhibition with MIC values of 1.25 μg/mL, similar to that of pharmaceutical concentrations currently used in tuberculosis treatment. These results justify further research into the value of these quinones as part of an original treatment for tuberculosis.
Post‐summer heavy rainfall events in Southeast Brazil associated with South Atlantic Convergence Zone
Authors: Lima Kellen Carla , Satyamurty Prakki
Published: January 2010

Heavy rainfall events (HREs) in the post‐summer month of March in Southeast Brazil cause disasters such as floods, mudslides and landslides, mainly because the soil becomes saturated by February. Forty‐five years of rainfall data show that heavy rainfall frequency increases again in the month of March. The composite anomaly fields of the atmospheric circulation during and before HREs associated with the formation of South Atlantic Convergence Zone show some special characteristics that may be used as a guide for early warning. The convergence of moisture flux in the troposphere over the region grows 40% during the 48 h before the HRE in March. Copyright © 2010 Royal Meteorological Society
A developer's people mover education
Authors: Parker Jeffrey A.
Published: January 2010

The Three Rivers Corporate Center office complex proposed to the City of Pittsburgh initially included a half‐mile, automated people mover system as a link to downtown. After four years of effort and substantial investment, the project was dropped and the people mover was never built. What happened and what lessons were learned are described by the project's would‐be developer. Issues affecting the commercial application of people movers are examined from a developer's perspective and recommendations for improving the marketability of people movers to real estate decisionmakers are offered for consideration.
An evaluation of vehicle deceleration profiles
Authors: Wortman Robert H. , Fox Thomas C.
Published: January 2010

Vehicles stopping at signalized intersections were examined for the purpose of evaluating the validity of the common assumption of constant and uniform deceleration rates. The data set consisted of the first vehicles to stop upon the onset of the yellow signal interval with measurements of the initial approach speed, deceleration time, and deceleration distance.

The deceleration rate may be computed using only two of the three measured values; thus the rate for each vehicle can be determined by three different equations. With nonuniform deceleration profiles, the equations will produce different values; and the degree of nonuniformity can be determined by comparing the differences in the computed deceleration rates.

The analysis of the field observations indicated that 69 percent of the vehicles demonstrated deceleration profiles associated with nonuniform deceleration rates. Furthermore, the deceleration profile and the degree of nonuniformity were found to be a function of the initial approach speed.