bluuebunny/crossref_metadata_2025 huggingface dataset:
A Novel Role for Plasmin-Mediated Degradation of Opsonizing Antibody in the Evasion of Host Immunity by Virulent, but Not Attenuated, Francisella tularensis
Authors: Crane Deborah D. , Warner Shayna L. , Bosio Catharine M.
Published: September 2009

Opsonization by Abs represents a critical component of the host immune response against many pathogens. The mechanisms by which virulent microbes evade this protective response are not completely understood. In disease mediated by Francisella tularensis, Ab can effectively protect against infections with attenuated strains, for example, LVS, but not virulent strains such as SchuS4. Thus, it is likely that SchuS4 has mechanisms, which are not present in LVS, that allow evasion of opsonization by Ab, dampening the protective effects of these host molecules. Here we demonstrate that evasion of Ab-mediated opsonization and phagocytosis by the highly virulent SchuS4 is associated with its ability to bind the host serine protease plasmin. SchuS4, but not the closely related LVS, bound active plasmin. Plasmin bound SchuS4 degraded exogenous and opsonizing Abs, whereas LVS failed to do so. Furthermore, plasmin-mediated inhibition of Ab opsonization by SchuS4 also inhibited Ab-mediated uptake of this bacterium by macrophages. Ab-mediated uptake of uncoated and opsonized SchuS4 elicited a strong proinflammatory response in infected macrophages. However, plasmin-coated, opsonized SchuS4 poorly elicited production of these protective proinflammatory cytokines. This unique host-pathogen interplay is a novel immune evasion strategy utilized by virulent F. tularensis, and it provides one explanation for the ability of Ab to protect against attenuated, but not virulent, strains of F. tularensis. This mechanism may also represent a more common hereto unrecognized strategy by which virulent bacteria evade detection and clearance by Ig.
Dimorphic Motifs in D0 and D1+D2 Domains of Killer Cell Ig-Like Receptor 3DL1 Combine to Form Receptors with High, Moderate, and No Avidity for the Complex of a Peptide Derived from HIV and HLA-A*2402
Authors: Sharma Deepti , Bastard Karine , Guethlein Lisbeth A. , Norman Paul J. , Yawata Nobuyo , Yawata Makoto , Pando Marcelo , Thananchai Hathairat , Dong Tao , Rowland-Jones Sarah , Brodsky Frances M. , Parham Peter
Published: September 2009

Comparison of mutant killer cell Ig-like receptor (KIR) 3DL1*015 substituted at natural positions of variation showed that tryptophan/leucine dimorphism at position 283 uniquely changes receptor conformation and can strongly influence binding of the A24nef tetramer. Dimorphic motifs at positions 2, 47, and 54 in D0 and 182 and 283 in D1+D2 distinguish the two 3DL1 lineages, typified by 3DL1*005 and 3DL1*015. The interlineage recombinant, KIR3DL1*001, combines D0 of 3DL1*005 with D1+D2 of 3DL1*015 and binds A24nef more strongly than either parent. In contrast, the reciprocal recombinant with D0 from 3DL1*015 and D1+D2 from 3DL1*005 cannot bind A24nef. Thus, D0 polymorphism directly affects the avidity of the KIR3DL1 ligand binding site. From these observations, multiple sequence alignment, and homology modeling, we constructed structural models for KIR3DL1 and its complex with A24nef. In these models, D0, D1, and D2 come together to form a binding surface for A24nef, which is contacted by all three Ig-like domains. A central pocket binds arginine 83, the only Bw4 motif residue essential for KIR3DL1 interaction, similar to the binding of lysine 80 in HLA-C by KIR2DL1. Central to this interaction is a salt bridge between arginine 83 of Bw4 and glutamate 282 of 3DL1, which juxtaposes the functionally influential dimorphism at position 283. Further 3DL1 mutants were tested and shown to have A24nef-binding properties consistent with the models. A24nef was not bound by KIR3DS1, the activating counterpart of KIR3DL1. Moreover, introducing any one of three residues specific to KIR3DS1, serine 163, arginine 166, or leucine 199, into 3DL1*015, abrogated A24nef binding.
Statistical analysis of the maternal death rate at the Ebonyi State University Teaching Hospital, Abakaliki, for the year ending 31 December 2007
Authors: Okeh Uchechukwu M.
Published: September 2009

Background: The maternal mortality rate in developing countries, such as Nigeria, remains relatively high, with the causes being multidimensional. The unbooked primigravidae with severe pre-eclampsia/eclampsia constitute a high risk group.Method: The data from the case notes of all the maternal deaths that occurred at the Ebonyi State University Teaching Hospital, Abakaliki, between 1 January and 31 December 2007 form the basis of this study. The case notes relating to all such deaths were stored in the office of the Head of the Department of Obstetrics and Gynaecology when the deaths occurred. Information was extracted from the case files at the end of 2007. Data relating to the total number of deliveries were obtained from the registers kept in the labour and isolation wards.Results: Of the 45 maternal deaths recorded, 40 (88.9%) were found to have occurred among the unbooked and 5 (11%) among the booked mothers, constituting a maternal mortality ratio (MMR) of 23 121.4 and 339.7 per 100 000 deliveries respectively. The combined mortality ratio was 2 735.6 per 100 000 deliveries. Fifteen (37.5%) unbooked primigravidae were found to have died of severe pre-eclampsia/eclampsia. A total of 1 645 mothers were noted to have delivered babies, of whom 1 472(89.5%) were booked, and 173 (10.5%) unbooked, with the hospital.Conclusion: Severe pre-eclampsia/eclampsia, haemorrhaging and sepsis were the major causes of death. A high maternal mortality rate was found to be common among the unbooked primigravidae, who are known usually to present late with pre-eclampsia/eclampsia. More research into the causes and management of pre-eclampsia/eclampsia is needed to reduce the high maternal death rate associated with it. The lack of antenatal care is also a high risk factor for maternal death.
Siderophore‐Binding Periplasmatic ProteinFhuDand Related Periplasmic Binding Proteins Involved in Bacterial Iron Uptake
Authors: Krewulak Karla D. , Köster Wolfgang , Vogel Hans J.
Published: September 2009

To fulfill their nutritional requirement for iron, many microorganisms synthesize low‐molecular‐weight iron‐chelating compounds calledsiderophores. These iron sources are transported into the gram‐negative bacterial cellviaspecific uptake pathways that include an outer membrane receptor, a periplasmic binding protein (PBP), and an inner membrane ATP‐binding cassette (ABC) transporter. Gram‐positive bacteria lack an outer membrane, and thus the uptake of the ferric siderophore involves a membrane‐anchored PBP and an ABC transporter. Siderophores are classified as hydroxamate, catecholate, or hydroxycarboxylate type siderophores. This review details what is currently known about the PBP, FhuD (Fhu — ferric hydroxamate uptake), involved in the uptake of hydroxamate‐type siderophores. In addition, several structurally related periplasmic binding proteins that mediate bacterial metal ion transport are also discussed.
Iron‐Binding Protein
Fut
A
1
Authors: Koropatkin Nicole , Pakrasi Himadri B , Smith Thomas J
Published: September 2009

FutA1 belongs to the bacterial extracellular solute‐binding protein family 1 and is part of an ATP‐binding cassette‐type (ABC‐type) transport system involved in the uptake of iron. In
Synechocystis
6803, the
futA1
(
slr1295)
and
futA2
(
slr0513
) genes encode periplasmic binding proteins that have been proposed to be part of a high‐affinity iron‐transport system, although these genes, along with those encoding the transmembrane pore and intracellular ATPase proteins, are widely distributed throughout the genome. While the solute‐binding domains in the cluster 9 ABC transport systems have a relatively rigid α‐helix running down the back of the protein, which restricts domain movement, FutA1 has two β‐strands connecting the two domains of the protein. It is likely that these β‐strands permit the large domain movement observed during iron binding and release. In FutA1, iron is chelated by four tyrosine and one histidine residues. These tyrosine residues do not move during the opening and closing of the binding‐site cleft. This is likely due to a strong secondary shell of interacting residues which also improve iron‐tyrosine interactions by increasing the electronegativity of the tyrosine hydroxyls. Unlike a number of other periplasmic iron‐binding proteins, there are no apparent anion interactions with the bound ferric iron.
[
Ni
Fe
] Hydrogenase Maturing Proteins
Hyp
C
,
Hyp
D
,
Hyp
E
Authors: Watanabe Satoshi , Miki Kunio
Published: September 2009

[NiFe] hydrogenases carry an NiFe(CO)(CN)
2
center at the active site, which catalyzes the reversible oxidation of molecular hydrogen. Hyp proteins (HypABCDEF) are required for the maturation of [NiFe] hydrogenase. HypA and HypB are involved in the insertion of the nickel atom. HypE and HypF catalyze the biosynthesis of the cyanide ligand in the form of HypE‐thiocyanate. HypC and HypD are assumed to deliver the iron atom with diatomic ligands to the active site of hydrogenase. The structures of HypC consist of an OB‐fold like β‐barrel domain and C‐terminal one or two α helices. The C‐terminal helices are shown to be quite flexible. The structure of HypE consists of two α/β domains and is similar to other PurM superfamily proteins. The C‐terminal tail of HypE adopts an outward extended conformation in the absence of adenosine 5′ triphosphate (ATP) or an inward closed conformation in the presence of ATP. The structure of HypD is composed of two α/β domains and an Fe–S cluster binding domain. Conserved regions of HypD show its probable iron binding and active sites for cyanation. The [4Fe–4 S] cluster environment of HypD is shown to be quite similar to that of ferredoxin : thioredoxin reductase (FTR). The cyanation reaction can be catalyzed through thiol redox signaling in the HypCDE complex.
Amyloids and Protein Aggregation—Analytical Methods
Authors: Li Huiyuan , Rahimi Farid , Sinha Sharmistha , Maiti Panchanan , Bitan Gal , Murakami Kazuma
Published: September 2009

More than 30 diseases are associated with amyloid‐forming proteins, which undergo conformational alterations and “misfolding” under particular conditions. These proteins deposit as insoluble proteinaceous aggregates generating disease‐specific histopathologic lesions. The proteins contributing to each disease have dissimilar sequences and native structures, yet they share the commonality of forming insoluble amyloid aggregates characterized by fibrillar morphology and cross‐β structure. Presently, it is thought that the predominant agents causing cell toxicity and tissue damage are soluble, prefibrillar assemblies of these proteins. Because of the metastable nature of these prefibrillar assemblies and the noncrystalline nature of fibrillar protein aggregates, structural study of amyloid proteins is difficult. As a result, structural characterization of these proteins is typically done using combinations of low‐resolution analytical methods. Here, we present a compendium of analytical methods used to study the secondary, tertiary, and quaternary structures, and morphology of prefibrillar and fibrillar assemblies of amyloid‐forming proteins.
Depth Profiling
Authors: Martin Guillaume , Garcia Philippe , Sauvage Thierry
Published: September 2009

Elemental depth profiles up to few micrometers below the surface of samples can be determined using nuclear methods. Two types of depth profiling techniques are mainly distinguished on the basis of the shape of the cross section of the reaction between incident particles and target atoms. First, for nonresonant reactions with a cross section that extends over a wide range of energies, the energy of detected ions may vary as a function of the depth at which they are emitted. The analysis of the target at a given incident energy therefore enables its elemental depth profiling by converting the energy of detected ions into their emission depth. Second, resonant reactions that show a sharp and strong resonance at a given energy usually provide the best depth resolutions. As incident ions penetrate the analyzed material, their energy decreases and most of detected particles originate from depths at which the incident ions have reached the resonance energy. In this case, several analyses are needed to probe the target at all relevant depths. The procedure to perform depth profiling analyses requires firstly the determination of the experimental conditions that optimize the depth resolution and secondly extracting from the experimental spectra depth profiles with accurate error bars.
Coprecipitation in Trace Element Analysis
Authors: Inagaki Kazumi , Zhu Yanbei , Miura Tsutomu , Chiba Koichi
Published: September 2009

Coprecipitation is one of the classical, but quite useful, techniques for separation/preconcentration for trace element analysis. Many elements can be easily collected with a carrier precipitate, and the handling is simpler and easier compared to that of other techniques such as solvent extraction and solid‐phase extraction. In addition, selective separation can also be designed by controlling of chemical and physical conditions in the procedure. In this section, mechanisms of coprecipitation, selection of a carrier precipitates, selectivity in coprecipitation, and typical examples of coprecipitation in trace element analysis are described.
Differential‐associative processing: A new strategy for learning highly‐similar concepts
Authors: Hannon Brenda , Lozano Gregorio , Frias Sarah , Picallo‐Hernandez Sandra , Fuhrman Robert
Published: September 2009

For many students concepts like fluid and crystallized intelligence are difficult to learn because they have highly‐similar definitions that are easy to confuse. The challenge of learning these highly‐similar, yet often confused concepts is further complicated by the fact that students are tested on exams about differences between the concepts. In this theoretically‐motivated research we test a new strategy for learning highly‐similar pairs of concepts, called differential‐associative processing. The results revealed that performance on multiple‐choice questions was higher when students learned highly‐similar concepts using differential‐associative processing rather than a strategy of their own choice, text‐based elaboration, or identifying similarities and differences. The results also revealed that students spontaneously transferred differential‐associative processing to a neutral control condition. Taken as a whole, the present study supports differential‐associative processing as a useful strategy for learning similar concepts. Copyright © 2009 John Wiley & Sons, Ltd.
Interactive elements for dynamically linked multiple representations in computer simulations
Authors: Rey Günter Daniel
Published: September 2009

Seventy‐three students learned central concepts about signal detection theory with an introductory text followed by a computer simulation. Each learner was randomly assigned to one of the three treatment groups: text boxes, scrollbars or drag and drop opportunities to modify parameters in the simulation. These three interactive elements were used for linking the different multiple representations in the simulation dynamically. Retention and transfer test, evaluation of the instructional material as well as time spent with the simulation were used as dependent measures. Learners who had to use scrollbars or had to modify parameters per drag and drop performed better on transfer, but not on retention, than did learners who had to use text boxes. Learners who had to modify parameters per drag and drop also evaluated the instructional material better than did learners who had to use text boxes. These results are consistent with the split‐attention principle. Copyright © 2009 John Wiley & Sons, Ltd.
Structural Evolution and Copper‐Ion Release Behavior of Cu‐pHEMA Hybrids Synthesized In Situ
Authors: Liu Yen‐Yu , Tung Tsan‐Hua , Liu Kun‐Ho , Chen San‐Yuan , Liu Dean‐Mo
Published: September 2009

A novel Cu‐pHEMA hybrid was successfully prepared by in situ photopolymerization of 2‐hydroxyethyl methacrylate (HEMA) monomer in the presence of Cu(II) copper ions, following an in situ chemical reduction. Experimental observations indicate that intermolecular interactions such as the coupling force and hydrogen bonding between the Cu and the hydroxyl groups further stabilize the hybrid structure to a considerable extent. Localization of the metallic copper particles within the pHEMA network structure as a result of those intermolecular interactions gives rise to the formation of discretely distributed nanocrystallites with particle sizes ranging from 5 to 25 nm in diameter. A crystallographic change of the Cu nanophase from an amorphous‐like to a crystalline structure is observed as the H2O:HEMA molar ratio increases, upon synthesis, accompanied with an increase in the particle size. A relatively slow and sustained release of the Cu (in the form of cupric ions) from the hybrids was measured for a time period of about 10 days, which also illustrates a Cu(II)‐induced proliferation of the endothelial cells over a relatively small range of release rate of the Cu from the hybrids. Such a new type of Cu‐loaded hybrid hydrogel is expected to be compatible and may be considered as a candidate biomaterial for biomedical/therapeutic uses.
Determination of Materials Selection Performance Indices Through the Combination of Numerical Modeling and Optimization Methods
Authors: Castillo German , Wargnier Hervé , Danis Michel , Brechet Yves
Published: September 2009

After translation, the first stages traditionally involved in the materials selection are filtration and classification, which require formulation of criteria (constraints or objectives) deduced from information written in the set of material requirements. These criteria, which are representative of the behavior of the material and the studied structure, must be formulated analytically in order to be used during selection stage. However, for complex behavior, analytical processing of models is no longer possible and it can be replaced by a combination of numerical resolution methods and an optimization method which make it possible to obtain approximate formal expressions of the criteria. In this paper, a complete selection method is proposed. The method is applied to the constraints as well as the objectives, in order to carry out the filtration and classification stages at the same time. The study of the thermomechanical behavior of a machine tool frame has been used to demonstrate the validity of the proposed method.
Insights into the Role of New Palladium Pincer Complexes as Robust and Recyclable Precatalysts for Suzuki–Miyaura Couplings in Neat Water
Authors: Inés Blanca , SanMartin Raul , Moure María Jesús , Domínguez Esther
Published: September 2009

Suzuki–Miyaura biaryl and diarylmethane syntheses via the coupling of arylboronic acids with aryl and arylmethyl bromides are performed in water by means of two new CNC‐type palladium pincer complexes. Good to excellent results (including high TON values and extended recycling procedures) are obtained in most cases for a range of electronically dissimilar halides and boronic acids. On the basis of a series of kinetics studies, transmission electron microscopy (TEM), mercury drop tests, and quantitative poisoning experiments, the real role of the latter palladacycles, closely linked to the formation and active participation of palladium nanoparticles, is discussed.
Proteinbiochips in der Biomedizin und Biotechnologie
Authors: Weinrich Dirk , Jonkheijm Pascal , Niemeyer Christof M. , Waldmann Herbert
Published: September 2009

Dank Fortschritten bei Immobilisierungsstrategien für Proteine sind Proteinbiochips in den letzten Jahren immer besser verfügbar geworden. Durch die Integration dieser Assay‐ und Analyseplattformen in die biomedizinische und biotechnologische Forschung konnte das Repertoire an Methoden für die Proteomik, die Biomarkerforschung und die Wirkstoffentwicklung deutlich vergrößert werden. In diesem Kurzaufsatz werden ausgewählte Entwicklungen bei der Anwendung von Proteinbiochips auf diesen Forschungsgebieten beleuchtet.
Applications of Protein Biochips in Biomedical and Biotechnological Research
Authors: Weinrich Dirk , Jonkheijm Pascal , Niemeyer Christof M. , Waldmann Herbert
Published: September 2009

Progress in the development of protein‐immobilization strategies and methods has made protein biochips increasingly accessible. The integration of these assay and analysis platforms into biomedical and biotechnological research has substantially expanded the repertoire of methods available for proteomics and biomarker research and for drug development. This Minireview highlights selected developments in the application of protein biochips in these fields.
Mechanical, thermal, and structural characterization of poly(ethylene terephthalate) and poly(butylene terephthalate) blend systems by the addition of postconsumer poly(ethylene terephthalate)
Authors: Baxi R. N. , Pathak S. U. , Peshwe D. R.
Published: September 2009

The focus of this study was mainly on the use of scrap poly(ethylene terephthalate) (PET) in poly(butylene terephthalate)‐rich blend systems. A good combination of tensile and impact properties was observed in the newly formed blend system with scrap PET. The morphology depicted controlled and well‐dispersed phases. The thorough mixing of the constituents was observed in the thermal study. For this innovative blend system, an attempt to correlate the mechanical, thermal, structural, morphological properties and the chemistry of the blend system seemed to be technoeconomical. This study contributed to the recycling of waste material. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Preparation and characterizations of polycaprolactone/green coconut fiber composites
Authors: Wu Chin‐San
Published: September 2009

The mechanical, thermal, and morphological properties of polycaprolactone (PCL) and green coconut fiber (GCF) composites were evaluated. Blends containing acrylic acid‐grafted PCL (PCL‐g‐AA/GCF) exhibited noticeably better mechanical properties due to better compatibility between the two components. The dispersion of GCF in the PCL‐g‐AA matrix was significantly more homogeneous due to the creation of branched and cross‐linked macromolecules via reactions between carboxyl groups in PCL‐g‐AA and hydroxyl groups in GCF. The tensile strength of the PCL‐g‐AA/GCF composites at break was considerably greater than that of PCL/GCF composites. In addition, the PCL‐g‐AA/GCF blend was more easily processed due to lower melt viscosity. Biodegradation tests were performed with each composite in an Acinetobacter baumannii BCRC 15556 environment. The mass of both composites was reduced by the GCF content within 4 weeks. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Accelerated aging versus realistic aging in aerospace composite materials. V. The effects of hot/wet aging in a structural epoxy composite
Authors: Dao B. , Hodgkin J. , Krstina J. , Mardel J. , Tian W.
Published: September 2009

Samples of an aerospace‐grade, carbon‐fiber epoxy composite (Hexcell 8552/IM7) were subject to long‐term (≈ 1 year) hot/wet aging and thermal spiking under different humidity levels and temperature conditions related to the “in‐service” conditions seen in military aircraft. Changes to the chemical and physico‐chemical structure of the composite were analyzed by a range of experimental techniques including gravimetric analysis, FTIR, and DMA, to compare the effects of the various aging conditions. The results indicated that, while the chemical changes (as seen by FTIR) in this well cured composite appeared to be only significant at the surface, they did appear to have a deeper influence on some of the major physical property changes observed, such as microcracking, glass‐transition‐temperature (Tg) variations, and Tan δ curves. These physical changes could not be fully explained by standard water‐absorption effects alone but could also be influenced by chemical changes similar to those seen at the surface. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Preparation and characterization of nanocomposites based on polylactides tethered with polyhedral oligomeric silsesquioxane
Authors: Lee Jong Hyun , Jeong Young Gyu
Published: September 2009

A series of polylactides tethered with polyhedral oligomeric silsesquioxane (POSS–PLAs) were synthesized via the ring‐opening polymerization of L‐lactide with 3‐hydroxypropylheptaisobutyl polyhedral oligomeric silsesquioxane (3‐hydroxypropylheptaisobutyl POSS) at a concentration of 0.02–2.00 mol % in the presence of a stannous(II) octoate catalyst.1H‐NMR spectra and a composition analysis of the POSS–PLA hybrids confirmed that 3‐hydroxypropylheptaisobutyl POSS served as an initiator for L‐lactide in the ring‐opening polymerization. X‐ray diffraction patterns evidenced that polyhedral oligomeric silsesquioxane (POSS) molecules of POSS–PLA hybrids were well dispersed without the formation of their crystalline aggregates. The POSS–PLA hybrid with 0.50 mol % POSS content was solution‐blended with a neat polylactide (PLA) homopolymer to obtain PLA/POSS–PLA nanocomposites with various POSS–PLA contents of 1–30 wt %. The X‐ray diffraction results of the PLA/POSS–PLA nanocomposites demonstrated that the POSS–PLA was well dispersed in the neat PLA matrix. The thermal and thermooxidative degradation properties of the nanocomposites were found to be improved at POSS–PLA contents of 1–20 wt %, compared to the neat PLA. The crystallization rates and crystallinities of the PLA/POSS–PLA nanocomposites were faster and higher, respectively, with increasing POSS–PLA content because of the nucleation effect of the POSS molecules in the neat PLA matrix. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Interfacial aspects of adhesion in polymer nanocomposite thin‐film devices
Authors: Murugaraj P. , Mainwaring D. E. , Chen L. G. , Sawant P. , Al Kobaisi M. , Yek W. M.
Published: September 2009

Nanoscale polymeric composites are important in many new electronic technologies, including lightweight and flexible devices and sensors. The influence of surface chemical treatments, which particularly affect the adhesion properties of carbon–polyimide nanocomposite thin films, was studied with infrared spectroscopy, electron microscopy, atomic force microscopy, and contact angle measurements with respect to corresponding polyimide thin films. The contact angles showed that the inclusion of carbon initially increased the hydrophilicity, whereas a potassium hydroxide treatment increased the hydrophilicity of the pure polyimide film and the polyimide component of the nanocomposite surface without increasing the hydrophilicity of the carbon nanoparticle component. Friction‐force atomic force microscopy was shown to be a powerful technique for confirming the relative wetting characteristics at the nanoscale. The lower hydrophilicity and activity of the carbon nanoparticles during adhesion reactions reduced the load at break, and this suggests that this conventional modification used for polyimides is less effective for their nanocomposite counterparts. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Synthesis and characterization of a novel covalently functionalized organoclay and its polypropylene nanocomposite
Authors: Du Xiaohua , Zhang Zhenjiang , Yu Haiou , Wan Dong , Xing Haiping , Tang Tao
Published: September 2009

A covalently functionalized organoclay was synthesized successfully through a condensation reaction of SiOH groups on the edge of montmorillonite (MMT) with acryloyl chloride followed by modification with hexadecyltrimethylammonium bromide (CTAB) via an ion‐exchange reaction. Fourier transform infrared confirmed that CC groups had been grafted to MMT sheets. Wide‐angle X‐ray diffraction measurements showed that CTAB had intercalated into MMT interlayers. The content of bonded acryloyl chloride was 2.42 wt % in the functionalized organoclay according to thermogravimetric analysis. Polypropylene (PP) nanocomposites were prepared by melt mixing. Rheological measurements and morphology observations confirmed that PP nanocomposites containing the organoclay bearing CC groups exhibited improved interfacial interaction between PP chains and MMT sheets. Thus, the PP nanocomposites showed not only higher storage modulus and complex viscosity values at low frequencies but also enhanced mechanical properties. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Studies on the self‐assembly of neat DBS and DBS/PPG organogels
Authors: Lai Wei‐Chi , Wu Chia‐Hui
Published: September 2009

The self‐assembly behavior of neat 1,3:2,4‐dibenzylidene‐D‐sorbitol (DBS) and DBS/poly(propylene glycol) (PPG) organogels has been investigated by scanning electron microscopy, polarizing optical microscopy, and rheological measurements. DBS molecules are capable of self‐organizing into fibrils and exhibit the birefringent spherulitic textures during cooling from the melt. On the other hand, DBS can self‐assemble into a fibrillar network in PPG to produce organogels. DBS/PPG organogels also reveal a spherulite‐like morphology. When a small amount of DBS is dispersed into a PPG matrix, we find that the spherulite sizes are much smaller than those of neat DBS. This is because the dilution of DBS causes DBS to self‐assemble in PPG at a lower temperature. Therefore, more nucleation sites and smaller spherulite sizes are found in the DBS/PPG organogel system. The rheological measurements demonstrate that the elastic modulus (G′) in DBS/PPG organogels increases as the DBS concentration increases. However, the increase in G′ is less obvious, as the DBS content exceeds 3 wt %. suggesting that the DBS networks become saturated. Also, it is found that these organogels require a certain period of time to reach thermodynamic equilibrium, depending on DBS concentrations. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Nucleation effect of inclusion complexes with different polyolefin as guest molecules on the crystallization of polypropylene
Authors: Li Chun , Isshiki Naoe , Saito Hiromu , Kohno Kazufumi , Toyota Akinori
Published: September 2009

The γ‐cyclodextrin (γ‐CD) inclusion complexes (ICs) with four kinds of polyolefin (PO) as guest molecules were prepared. The crystallization behavior of isotactic polypropylene (iPP) blended with the γ‐CD and γ‐CD–PO ICs was investigated by differential scanning calorimetry, polarized optical microscopy, and light scattering. The iPP blended with the ICs was found to exhibit higher crystallization temperature (TC), smaller spherulites, and faster crystallization rate than those of neat iPP, indicating that the ICs play a role of nucleating agent on the crystallization of iPP and induce accelerated crystallization. The IC with PO having higher TC as guest molecules showed higher nucleation effect than the IC with PO having lower TC as guest molecules. The results suggest that the nucleation effect of these ICs was affected by the kinds of the guest molecules. The higher TC guest molecules could result in higher nucleation effect. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Polyacrylamide‐g‐alginate‐based electrically responsive hydrogel for drug delivery application: Synthesis, characterization, and formulation development
Authors: Kulkarni Raghavendra V. , Setty Chitrali Mallikarjun , Sa Biswanath
Published: September 2009

An electrically responsive hydrolyzed polyacrylamide‐grafted‐sodium alginate (H‐PAAm‐g‐SA)‐based membrane‐controlled transdermal drug delivery systems were developed and evaluated. The grafting reaction was confirmed by Fourier transform infrared spectroscopy, elemental analysis, and thermogravimetric analysis. On application of electric stimulus, the swollen H‐PAAm‐g‐SA hydrogel was deswelled in the vicinity of electrodes. The drug release was greater in the presence of electric stimulus when compared with passive diffusion, and it was found to be dependent on the applied electric current strength, concentration of H‐PAAm‐g‐SA copolymer in the reservoir, and cross‐link density of rate‐controlling membrane. A pulsatile pattern of drug release was observed when the electric stimulus was switched “on” and “off.” The skin histopathology study suggested that, after application of an electrical stimulus, changes were in the structure of stratum corneum. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Hybrid emulsifiers enhancing polymerization stabilities and properties of pressure sensitive adhesives
Authors: Bai Yong‐Ping , Zhao Liang , Shao Lu
Published: September 2009

In this study, a series of (anionic and nonionic) emulsifiers were investigated to prepare acrylic pressure sensitive adhesives (PSA) with core‐shell structure by semicontinuous emulsion polymerization. The cloud point of different emulsifiers was characterized to explain the emulsifier effects on the emulsification ability. It was interestingly found that the hybrid emulsifiers (anionic coupling with nonionic) with optimized compositions could enhance the stability of emulsion system and improve the properties of PSA compared with the mono‐emulsifier. The stability of emulsion polymerization, the appearance of the emulsion system and the properties of PSA were studied in details by changing the proportion and the content of hybrid emulsifiers. When the ratio of sodium dodecyl sulfate (SDS: anionic emulsifier) to polyoxyethylene alkyl phenyl ether (OP‐10: nonionic emulsifier) reached 2 : 1, the content of hybrid emulsifiers reached 3 wt % and the reaction temperature was around 80°C, a better emulsion system was obtained in terms of comprehensive properties. At this condition, the synthesized PSA demonstrated the good holding power and 180° peel strength properties with fair tacky property, which was promising for industrial applications. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Electrospinning of waterborne polyurethanes
Authors: Buruaga Lorea , Sardon Haritz , Irusta Lourdes , González Alba , Fernández‐Berridi María José , Iruin Juan José
Published: September 2009

Polyurethane (PU) fibers were obtained by electrospinning of waterborne PU dispersions. As dispersion cannot be electrospun, a water‐soluble polymer (poly (ethylene oxide) (PEO)) was dissolved in the PU dispersion and fibers were obtained from electrospinning the resulting mixture. Pure PU fibers were obtained after removing PEO with water extraction. Continuous PU fibers were obtained using a PU/PEO weight ratio higher than 2.5. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Atomic force microscopy and contact angle studies of polymerizable gemini surfactant admicelles on mica
Authors: Asnachinda Emma , O'Haver John H. , Sabatini David A. , Khaodhiar Sutha
Published: September 2009

Atomic force microscopy (AFM) was used to directly observe and characterize a polymer‐modified mica surface prepared using a polymerizable gemini surfactant. Normal tapping mode and contact mode AFM were used to image the treated mica surface morphologies in air and liquid environments, respectively. The root mean square (RMS) roughness of mica surfaces before and after surface modification and polymerization was analyzed from these scans. To determine the effect of styrene adsolubilization on the surfactant‐modified mica, AFM measurements of the modified mica were made at various styrene concentrations. Contact angle measurements were also made to further characterize the nature of the surfactant‐modified mica surface. The surface morphology and surface hydrophilicity were observed to be different for the modified mica after polymerization. In addition, the polymerized surface maintained its morphology after washing/desorption studies demonstrating the stability of the polymerized surfactant film. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
The effect of incorporation of POSS units on polymer blend compatibility
Authors: Li Shuyan , Simon George P. , Matisons Janis G.
Published: September 2009

In this work, the compatibility of poly(methyl methacrylate) (PMMA) and polystyrene (PS) polymers with their polyhedral oligomeric silsesquioxane (POSS) copolymers combined by solution blending is investigated, to determine the effect of incorporation of the POSS unit on polymer compatibility. The morphology of these tethered POSS copolymer/polymer blends was studied by electron microscopy, thermal analysis, and density. Although the basic PS/PMMA blend was clearly immiscible, it was also found that the incorporation of POSS into the PS chain led to incompatibility when the POSScoPS copolymer was blended with PS homopolymer. However, conversely, in the case where the POSS moiety was included as part of a copolymer with PMMA, the copolymer was miscible with the PMMA homopolymer. The presence of isobutyl units on the corners of POSS cage is clearly sufficient to encourage miscibility with PMMA. Interestingly, blends of the two different POSS copolymers led to an immiscible structure, despite having the common POSS units, the interactions between the POSS moieties clearly not being sufficient to drive compatibility. The POSS copolymers have also been used as interfacial agents in immiscible PS and PMMA blend, and it has been found that the appearance of the interface bonding is improved, although the phase morphology is only slightly changed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Degradable poly(ester amine) based on poly(ethylene glycol) dimethacrylate and polyethylenimine as a gene carrier
Authors: Yu Jia‐Hui , Huang Jin , Nah Jae‐Woon , Cho Myung‐Haing , Cho Chong‐Su
Published: September 2009

Degradable poly(ester amine) (PEA) based on poly(ethylene glycol) dimethacrylate (PMEG) and polyethylenimine (PEI) were synthesized by Michael addition reaction. The ratios of PEI to PMEG in PEAs were 0.99, 1.02, and 1.07 with corresponding number‐average molecular weight of 1.3 × 104, 1.2 × 104, and 0.9 × 104, respectively. Degradation rate of PEA at pH 7.4 was higher than that at pH 5.6. Good plasmid condensation and protection ability was shown when N/P molar ratio of PEA to DNA was above 15 (N: nitrogen element in PEA, P: phosphate in DNA). PEA/DNA complexes had positive zeta potential, narrow size distribution, good dispersity, and spheric shape with size below 250 nm when N/P ratio was above 30, suggestion of their endocytosis potential. Compared with PEI 25 KDa, the PEAs showed essential nontoxic to HeLa, HepG2 and 293T cells. With an increase in the molecular weight of PMEG, the transfection efficiency of PEAs in HeLa, HepG2 and 293T showed a tendency to decrease as well as the percent decrease of gene transfection efficiency with serum. The mechanism of PEA‐mediated gene transfection was attributed to “proton sponge effect” of PEI in the PEA. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Kinetic rate equation combining ultraviolet‐induced curing and thermal curing. I. Bismaleimide system
Authors: Lin Rong‐Hsien , Huang Ru‐Yu , Yen Fu‐Shan , Chen Yi‐Hung , Ho Tzung‐Han
Published: September 2009

A novel and general kinetic rate equation combining ultraviolet‐induced (UV‐induced) curing and thermal curing was successfully derived from the conventional thermal‐kinetic rate equation. This proposed novel kinetic rate equation can be applicable to the curing system either simultaneously or individually by UV‐induced and thermal cure methods. This general kinetic rate equation is composed of the reaction order n, activation energy Ea, curing temperature T, energy barrier of photoinitiation EQ, intensity of UV radiation Q, concentration of photoinitiator [I], and a few other parameters. The proposed equation was supported by experimental data based on the curing systems of 4,4′‐bismaleimidodiphenylmethane (BMI) and 2,2‐bis(4‐(4 maleimido phenoxy) phenyl propane (BMIP). The BMI and BMIP systems were isothermally cured at various temperatures, or simultaneously cured with varying intensity of UV radiation (wavelength 365 nm). Conversion levels for the various cured samples were subsequently measured with a FTIR spectrometer. The reaction order n = 1.2, activation energy Ea = 40,800 J/mol, and EQ = 7.5 mW/cm2 were obtained for curing BMI system. The reaction order n = 1.3, activation energy Ea = 53,000 J/mol, and EQ = 9.1 mW/cm2 were obtained for curing BMIP system. The values of n and Ea in the same curing system (BMI or BMIP) are irrespective of the curing method (either simultaneously or individually by UV‐induced and thermal cure methods). The salient results of this study show that UV radiation only enhances the initiation rate and UV ration do not influence the activation energy Ea. The experimental results are reasonably well represented by these semi‐empirical expressions.© 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Divergences without probability vectors and their applications
Authors: Sachlas Athanasios , Papaioannou Takis
Published: September 2009

In general, divergences and measures of information are defined for probability vectors. However, in some cases, divergences are ‘informally’ used to measure the discrepancy between vectors, which are not necessarily probability vectors. In this paper we examine whether divergences with nonprobability vectors in their arguments share the properties of probabilistic or information theoretic divergences. The results indicate that divergences with nonprobability vectors share, under some conditions, some of the properties of probabilistic or information theoretic divergences and therefore can be considered and used as information measures. We then use these divergences in the problem of actuarial graduation of mortality rates. Copyright © 2009 John Wiley & Sons, Ltd.
Response Adaptive Designs with a Variance‐penalized Criterion
Authors: Yi Yanqing , Wang Xikui
Published: September 2009

We consider a response adaptive design of clinical trials with a variance‐penalized criterion. It is shown that this criterion evaluates the performance of a response adaptive design based on both the number of patients assigned to the better treatment and the power of the statistical test. A new proportion of treatment allocation is proposed and the doubly biased coin procedure is used to target the proposed proportion. Under reasonable assumptions, the proposed design is demonstrated to generate an asymptotic variance of allocation proportions, which is smaller than that of the drop‐the‐loser design. Simulation comparisons of the proposed design with some existing designs are presented.
TNF‐α, a potent lipid metabolism regulator
Authors: Chen Xiuping , Xun Keli , Chen Lidian , Wang Yitao
Published: September 2009

As a multifunctional cytokine, tumor necrosis factor alpha (TNF‐α) exerts a series of biological actions in different cells, tissues, organs, and species and has been demonstrated to regulate and interfere with energy metabolism, especially lipid homeostasis. A large body of researches suggested that the effects of TNF‐α on lipid metabolism mainly include five aspects: (1) suppresses free fatty acid (FFA) uptake and promotes lipogenesis; (2) induces lipolysis; (3) inhibits lipid‐metabolism‐related enzymes activity; (4) regulates cholesterol metabolism; (5) regulates other adipocyte‐derived adipokines. The molecular mechanisms underlying these actions are complex and several signal transduction pathways might be involved. Regulation of metabolism‐related gene expression at transcriptional and protein levels and impact on enzymes activity might be of importance. Identification and verification of these pathways might provide novel potential strategies and drug targets for dyslipidemia therapy. However, the inconsistent and even conflict conclusions on lipid profile drawn from human subjects after infliximab therapy poses the possibility that the effect of TNF‐α on lipid metabolism might be more complicated than it appeared to be. Copyright © 2009 John Wiley & Sons, Ltd.
Phytoremediation of Sb, As, Cu, and Zn from Contaminated Water by the Aquatic Macrophyte Eleocharis acicularis
Authors: Ha Nguyen Thi Hoang , Sakakibara Masayuki , Sano Sakae
Published: September 2009

Sb, As, Cu, and Zn toxicity and contamination have become a growing concern in recent years. Phytoremediation, a plant based and cost effective technology, may be an effective approach in the cleanup of water contaminated by these metals. In this study, the aquatic macrophyte Eleocharis acicularis was used in laboratory and field experiments to assess its capability to accumulate Sb, As, Cu, and Zn, and thereby investigate its potential application in phytoremediation. The results showed that E. acicularis adapted well to water contaminated by these metals. The removal rates of Sb, As, Cu, and Zn in the laboratory experiment were 3.04, 2.75, 0.417, and 1.49 μg/L/day, respectively. The highest concentrations of these metals accumulated in E. acicularis after 10 days of the laboratory experiment were 6.29, 6.44, 20.5, and 73.5 mg/kg dry weight, respectively. Only 8% of As, 12% of Sb, 87% of Cu and 93% of Zn removed from the water were used by E. acicularis. The highest concentrations of Sb, As, Cu, and Zn accumulated in E. acicularis after 10 wk of the field experiment were 76.0, 22.4, 33.9, and 266 mg/kg dry weight, respectively. The results indicate that E. acicularis has the ability to accumulate Sb, As, Cu, and Zn from contaminated water.
Flow Discharge Modeling in Open Canals Using a New Fuzzy Modeling Technique (SMRGT)
Authors: Toprak Z. Fuat
Published: September 2009

The main goal of this study was to research the answer to two important questions in flow modeling; i) how to optimally design the cross‐section of an open channel for a given flow, and ii) in the case of selecting the fuzzy method for modeling, how to construct the membership functions (MFs) and fuzzy rules (FRs) such that the system yields the best results. The first question is answered in order to minimize difficulties in excavation and related costs by using the appropriate flow velocity. To provide the best answer researchers use several methods. The second question is answered in order to minimize model error. For this aim, there are many algorithms proposed by researchers in the literature. In this paper, the fuzzy logic method was used for open canal flow modeling. Furthermore, a simple membership function and fuzzy rule generation technique (SMRGT) is introduced, and used for fuzzy modeling. Two fuzzy models, each for different cross‐sectional shape, are presented in this study as an application of SMRGT. The comparison depends on various statistics, mean absolute relative error, and contour maps showed that the fuzzy models were successful in open channel flow modeling and SMRGT is useful for MF (membership function) and FR (fuzzy rule) generation.
Exploiting semantics and virtualization for SLA‐driven resource allocation in service providers
Authors: Ejarque Jorge , de Palol Marc , Goiri Íñigo , Julià Ferran , Guitart Jordi , Badia Rosa M. , Torres Jordi
Published: September 2009

Resource management is a key challenge that service providers must adequately face in order to accomplish their business goals. This paper introduces a framework, the semantically enhanced resource allocator (SERA), aimed to facilitate service provider management, reducing costs and at the same time fulfilling the QoS agreed with the customers. The SERA assigns resources depending on the information given by the service providers according to its business goals and on the resource requirements of the tasks. Tasks and resources are semantically described and these descriptions are used to infer the resource assignments. Virtualization is used to provide an application specific and isolated virtual environment for each task. In addition, the system supports fine‐grain dynamic resource distribution among these virtual environments based on Service‐Level Agreements. The required adaptation is implemented using agents, guarantying enough resources to each task in order to meet the agreed performance goals. Copyright © 2009 John Wiley & Sons, Ltd.