bluuebunny/crossref_metadata_2025 huggingface dataset:
Follicular Dendritic Cells Activate HIV-1 Replication in Monocytes/Macrophages through a Juxtacrine Mechanism Mediated by P-Selectin Glycoprotein Ligand 1
Authors: Ohba Kenji , Ryo Akihide , Dewan Md. Zahidunnabi , Nishi Mayuko , Naito Toshio , Qi Xiaohua , Inagaki Yoshio , Nagashima Yoji , Tanaka Yuetsu , Okamoto Takashi , Terashima Kazuo , Yamamoto Naoki
Published: June 2009

Follicular dendritic cells (FDCs) are located in the lymphoid follicles of secondary lymphoid tissues and play a pivotal role in the selection of memory B lymphocytes within the germinal center, a major site for HIV-1 infection. Germinal centers are composed of highly activated B cells, macrophages, CD4+T cells, and FDCs. However, the physiological role of FDCs in HIV-1 replication remains largely unknown. We demonstrate in our current study that FDCs can efficiently activate HIV-1 replication in latently infected monocytic cells via an intercellular communication network mediated by the P-selectin/P-selectin glycoprotein ligand 1 (PSGL-1) interaction. Upon coculture with FDCs, HIV-1 replication was significantly induced in infected monocytic cell lines, primary monocytes, or macrophages. These cocultures were found to synergistically induce the expression of P-selectin in FDCs via NF-κB activation and its cognate receptor PSGL-1 in HIV-1-infected cells. Consistent with this observation, we find that this response is significantly blocked by antagonistic Abs against PSGL-1 and almost completely inhibited by PSGL-1 small interfering RNA. Moreover, a selective inhibitor for Syk, which is a downstream effector of PSGL-1, blocked HIV-1 replication in our cultures. We have thus elucidated a novel regulatory mechanism in which FDCs are a potent positive bystander that facilitates HIV-1 replication in adjacent infected monocytic cells via a juxtacrine signaling mechanism.
Pleiotropic Roles of S100A12 in Coronary Atherosclerotic Plaque Formation and Rupture
Authors: Goyette Jesse , Yan Wei Xing , Yamen Eric , Chung Yuen Ming , Lim Su Yin , Hsu Kenneth , Rahimi Farid , Di Girolamo Nick , Song Changjie , Jessup Wendy , Kockx Maaike , Bobryshev Yuri V. , Freedman S. Ben , Geczy Carolyn L.
Published: June 2009

Macrophages, cytokines, and matrix metalloproteinases (MMP) play important roles in atherogenesis. The Ca2+-binding protein S100A12 regulates monocyte migration and may contribute to atherosclerosis by inducing proinflammatory cytokines in macrophages. We found significantly higher S100A12 levels in sera from patients with coronary artery disease than controls and levels correlated positively with C-reactive protein. S100A12 was released into the coronary circulation from ruptured plaque in acute coronary syndrome, and after mechanical disruption by percutaneous coronary intervention in stable coronary artery disease. In contrast to earlier studies, S100A12 did not stimulate proinflammatory cytokine production by human monocytes or macrophages. Similarly, no induction of MMP genes was found in macrophages stimulated with S100A12. Because S100A12 binds Zn2+, we studied some functional aspects that could modulate atherogenesis. S100A12 formed a hexamer in the presence of Zn2+; a novel Ab was generated that specifically recognized this complex. By chelating Zn2+, S100A12 significantly inhibited MMP-2, MMP-9, and MMP-3, and the Zn2+-induced S100A12 complex colocalized with these in foam cells in human atheroma. S100A12 may represent a new marker of this disease and may protect advanced atherosclerotic lesions from rupture by inhibiting excessive MMP-2 and MMP-9 activities by sequestering Zn2+.
Identification of a Major Susceptibility Locus for Lethal Graft-versus-Host Disease in MHC-Matched Mice
Authors: Cao Thai M. , Lazzeroni Laura C. , Tsai Schickwann , Pang Wendy W. , Kao Amy , Camp Nicola J. , Thomas Alun , Shizuru Judith A.
Published: June 2009

Graft-vs-host disease (GVHD) is the major cause of morbidity and mortality after allogeneic hemopoietic cell transplantation. From a genetic perspective, GVHD is a complex phenotypic trait. Although it is understood that susceptibility results from interacting polymorphisms of genes encoding histocompatibility Ags and immune regulatory molecules, a detailed and integrative understanding of the genetic background underlying GVHD remains lacking. To gain insight regarding these issues, we performed a forward genetic study. A MHC-matched mouse model was used in which irradiated recipient BALB.K and B10.BR mice demonstrate differential susceptibility to lethal GHVD when transplanted using AKR/J donors. Assessment of GVHD in (B10.BR × BALB.K)F1 mice revealed that susceptibility is a dominant trait and conferred by deleterious alleles from the BALB.K strain. To identify the alleles responsible for GVHD susceptibility, a genome-scanning approach was taken using (B10.BR × BALB.K)F1 × B10.BR backcross mice as recipients. A major susceptibility locus, termed the Gvh1 locus, was identified on chromosome 16 using linkage analysis (logarithm of the odds, 9.1). A second locus was found on chromosome 13, named Gvh2, which had additive but protective effects. Further identification of Gvh genes by positional cloning may yield new insight into genetic control mechanisms regulating GVHD and potentially reveal novel approaches for effective GVHD therapy.
Elimination of Immunodominant Epitopes from Multispecific DNA-Based Vaccines Allows Induction of CD8 T Cells That Have a Striking Antiviral Potential
Authors: Riedl Petra , Wieland Andreas , Lamberth Kasper , Buus Soren , Lemonnier Francois , Reifenberg Kurt , Reimann Jörg , Schirmbeck Reinhold
Published: June 2009

Immunodominance limits the TCR diversity of specific antiviral CD8 T cell responses elicited by vaccination or infection. To prime multispecific T cell responses, we constructed DNA vaccines that coexpress chimeric, multidomain Ags (with CD8 T cell-defined epitopes of the hepatitis B virus (HBV) surface (S), core (C), and polymerase (Pol) proteins and/or the OVA Ag as stress protein-capturing fusion proteins. Priming of mono- or multispecific, HLA-A*0201- or Kb-restricted CD8 T cell responses by these DNA vaccines differed. Kb/OVA257–264- and Kb/S190–197-specific CD8 T cell responses did not allow priming of a Kb/C93–100-specific CD8 T cell response in mice immunized with multidomain vaccines. Tolerance to the S- Ag in transgenic Alb/HBs mice (that express large amounts of transgene-encoded S- Ag in the liver) facilitated priming of subdominant, Kb/C93–100-specific CD8 T cell immunity by multidomain Ags. The “weak” (i.e., easily suppressed) Kb/C93–100-specific CD8 T cell response was efficiently elicited by a HBV core Ag-encoding vector in 1.4HBV-Smut tg mice (that harbor a replicating HBV genome that produces HBV surface, core, and precore Ag in the liver). Kb/C93–100-specific CD8 T cells accumulated in the liver of vaccinated 1.4HBV-Smut transgenic mice where they suppressed HBV replication. Subdominant epitopes in vaccines can hence prime specific CD8 T cell immunity in a tolerogenic milieu that delivers specific antiviral effects to HBV-expressing hepatocytes.
Structural Bases for the Affinity-Driven Selection of a Public TCR against a Dominant Human Cytomegalovirus Epitope
Authors: Gras Stéphanie , Saulquin Xavier , Reiser Jean-Baptiste , Debeaupuis Emilie , Echasserieau Klara , Kissenpfennig Adrien , Legoux François , Chouquet Anne , Le Gorrec Madalen , Machillot Paul , Neveu Bérangère , Thielens Nicole , Malissen Bernard , Bonneville Marc , Housset Dominique
Published: June 2009

Protective T cell responses elicited along chronic human CMV (HCMV) infections are sometimes dominated by CD8 T cell clones bearing highly related or identical public TCR in unrelated individuals. To understand the principles that guide emergence of these public T cell responses, we have performed structural, biophysical, and functional analyses of an immunodominant public TCR (RA14) directed against a major HLA-A*0201-restricted HCMV Ag (pp65495–503) and selected in vivo from a diverse repertoire after chronic stimulations. Unlike the two immunodominant public TCRs crystallized so far, which focused on one peptide hotspot, the HCMV-specific RA14 TCR interacts with the full array of available peptide residues. The conservation of some peptide-MHC complex-contacting amino acids by lower-affinity TCRs suggests a shared TCR-peptide-MHC complex docking mode and supports an Ag-driven selection of optimal TCRs. Therefore, the emergence of a public TCR of an oligoclonal Ag-specific response after repeated viral stimulations is based on a receptor displaying a high structural complementarity with the entire peptide and focusing on three peptide hotspots. This highlights key parameters underlying the selection of a protective T cell response against HCMV infection, which remains a major health issue in patients undergoing bone marrow transplantation.
The Initial Phase of an Immune Response Functions to Activate Regulatory T Cells
Authors: O'Gorman William E. , Dooms Hans , Thorne Steve H. , Kuswanto Wilson F. , Simonds Erin F. , Krutzik Peter O. , Nolan Garry P. , Abbas Abul K.
Published: June 2009

An early reaction of CD4+ T lymphocytes to Ag is the production of cytokines, notably IL-2. To detect cytokine-dependent responses, naive Ag-specific T cells were stimulated in vivo and the presence of phosphorylated STAT5 molecules was used to identify the cell populations responding to IL-2. Within hours of T cell priming, IL-2-dependent STAT5 phosphorylation occurred primarily in Foxp3+ regulatory T cells. In contrast, the Ag-specific T cells received STAT5 signals only after repeated Ag exposure or memory differentiation. Regulatory T cells receiving IL-2 signals proliferated and developed enhanced suppressive activity. These results indicate that one of the earliest events in a T cell response is the activation of endogenous regulatory cells, potentially to prevent autoimmunity.
Downstream Signals for MyD88-Mediated Phagocytosis of Borrelia burgdorferi Can Be Initiated by TRIF and Are Dependent on PI3K
Authors: Shin Ok S. , Miller Lloyd S. , Modlin Robert L. , Akira Shizuo , Uematsu Satoshi , Hu Linden T.
Published: June 2009

We previously have shown that MyD88 is important for uptake of Borrelia burgdorferi by bone marrow derived macrophages (BMDMs). The mechanism by which MyD88 is involved in uptake of B. burgdorferi is currently is not well characterized. Here, we report that MyD88-mediated defect in the phagocytosis of B. burgdorferi can be complemented by TLR3/Toll/IL-1R domain-containing adaptor-inducing IFN-β (TRIF) activation in BMDMs from MyD88−/− mice. This effect of TLR3/TRIF activation was not due to its induction of type I IFNs, suggesting instead a convergence of signaling pathways downstream of MyD88 and TRIF. To characterize signaling pathways involved in MyD88-mediated phagocytosis of B. burgdorferi, BMDMs were treated with specific inhibitors of MAPK, protein kinase C, JAK/STAT, or PI3K. Only inhibition of PI3K resulted in a significant decrease of B. burgdorferi uptake. Consistent with this, B. burgdorferi activation of MyD88 or TLR3/TRIF signaling resulted in increased activity of PI3K. Additionally, association of B. burgdorferi with actin-related protein (Arp2/3) complexes, which facilitate actin rearrangements during phagocytosis, was similarly reduced in MyD88−/− BMDMs and in BMDMs treated with a PI3K inhibitor. Taken together, these findings define an essential pathway whereby downstream signals from MyD88 or TRIF converge on PI3K, which triggers actin polymerization to initiate the phagocytosis of B. burgdorferi.
Spark Plasma Sintering as a Useful Technique to the Nanostructuration of Piezo‐Ferroelectric Materials
Authors: Hungría Teresa , Galy Jean , Castro Alicia
Published: June 2009

This review gathers detail on the processing of piezo‐ferroelectric ceramic materials by spark plasma sintering for the first time. The results reported here clearly indicate that it is a powerful technique and opens the possibility of processing ceramics with controlled sub‐micron or even nanoscale grain sizes.
Restorable Type Conversion of Carbon Nanotube Transistor Using Pyrolytically Controlled Antioxidizing Photosynthesis Coenzyme
Authors: Kang Bo Ram , Yu Woo Jong , Kim Ki Kang , Park Hyeon Ki , Kim Soo Min , Park Yongjin , Kim Gunn , Shin Hyeon‐Jin , Kim Un Jeong , Lee Eun‐Hong , Choi Jae‐Young , Lee Young Hee
Published: June 2009

Here, a pyrolytically controlled antioxidizing photosynthesis coenzyme, β‐Nicotinamide adenine dinucleotide, reduced dipotassium salt (NADH) for a stable n‐type dopant for carbon nanotube (CNT) transistors is proposed. A strong electron transfer from NADH, mainly nicotinamide, to CNTs takes place during pyrolysis so that not only the type conversion from p‐type to n‐type is realized with 100% of reproducibility but also the on/off ratio of the transistor is significantly improved by increasing on‐current and/or decreasing off‐current. The device was stable up to a few months with negligible current changes under ambient conditions. The n‐type characteristics were completely recovered to an initial doping level after reheat treatment of the device.
Molecular Design of Unsymmetrical Squaraine Dyes for High Efficiency Conversion of Low Energy Photons into Electrons Using TiO2 Nanocrystalline Films
Authors: Geiger Thomas , Kuster Simon , Yum Jun‐Ho , Moon Soo‐Jin , Nazeeruddin Mohammad K. , Grätzel Michael , Nüesch Frank
Published: June 2009

An optimized unsymmetrical squaraine dye 5‐carboxy‐2‐[[3‐[(2,3‐dihydro‐1, 1‐dimethyl‐3‐ethyl‐1H‐benzo[e]indol‐2‐ylidene)methyl]‐2‐hydroxy‐4‐oxo‐2‐cyclobuten‐1‐ylidene]methyl]‐3,3‐dimethyl‐1‐octyl‐3H‐indolium (SQ02) with carboxylic acid as anchoring group is synthesized for dye‐sensitized solar cells (DSCs). Although the π‐framework of SQ02 is insignificantly extended compared to its antecessor squaraine dye SQ01, photophysical measurements show that the new sensitizer has a much higher overall conversion efficiency η of 5.40% which is improved by 20% when compared to SQ01. UV‐vis spectroscopy, cyclic voltammetry and time dependent density functional theory calculations are accomplished to rationalize the higher conversion efficiency of SQ02. A smaller optical band gap including a higher molar absorption coefficient leads to improved light harvesting of the solar cell and a broadened photocurrent spectrum. Furthermore, all excited state orbitals relevant for the π–π* transition in SQ02 are delocalized over the carboxylic acid anchoring group, ensuring a strong electronic coupling to the conduction band of TiO2 and hence a fast electron transfer.
Self‐Assembly of a Donor‐Acceptor Dyad Across Multiple Length Scales: Functional Architectures for Organic Electronics
Authors: Mativetsky Jeffrey M. , Kastler Marcel , Savage Rebecca C. , Gentilini Desirée , Palma Matteo , Pisula Wojciech , Müllen Klaus , Samorì Paolo
Published: June 2009

Molecular dyads based on polycyclic electron donor (D) and electron acceptor (A) units represent suitable building blocks for forming highly ordered, solution‐processable, nanosegregated D‐A domains for potential use in (opto)electronic applications. A new dyad, based on alkyl substituted hexa‐peri‐hexabenzocoronene (HBC) and perylene monoimide (PMI) separated by an ethinylene linker, is shown to have a high tendency to self‐assemble into ordered supramolecular arrangements at multiple length scales: macroscopic extruded filaments display long‐range crystalline order, nanofiber networks are produced by simple spin‐coating, and monolayers with a lamellar packing are formed by physisorption at the solution‐HOPG interface. Moreover, highly uniform mesoscopic ribbons bearing atomically flat facets and steps with single‐molecule heights self‐assemble upon solvent‐vapor annealing. Electrical measurements of HBC‐PMI films and mesoscopic ribbons in a transistor configuration exhibit ambipolar transport with well balanced p‐ and n‐type mobilities. Owing to the increased level of order at the supramolecular level, devices based on ribbons show mobility increases of more than one order of magnitude.
Brittle‐to‐Ductile Transition in Uniaxial Compression of Silicon Pillars at Room Temperature
Authors: Östlund Fredrik , Rzepiejewska‐Malyska Karolina , Leifer Klaus , Hale Lucas M. , Tang Yuye , Ballarini Roberto , Gerberich William W. , Michler Johann
Published: June 2009

Robust nanostructures for future devices will depend increasingly on their reliability. While great strides have been achieved for precisely evaluating electronic, magnetic, photonic, elasticity and strength properties, the same levels for fracture resistance have been lacking. Additionally, one of the self‐limiting features of materials by computational design is the knowledge that the atomistic potential is an appropriate one. A key property in establishing both of these goals is an experimentally‐determined effective surface energy or the work per unit fracture area. The difficulty with this property, which depends on extended defects such as dislocations, is measuring it accurately at the sub‐micrometer scale. In this Full Paper the discovery of an interesting size effect in compression tests on silicon pillars with sub‐micrometer diameters is presented: in uniaxial compression tests, pillars having a diameter exceeding a critical value develop cracks, whereas smaller pillars show ductility comparable to that of metals. The critical diameter is between 310 and 400 nm. To explain this transition a model based on dislocation shielding is proposed. For the first time, a quantitative method for evaluating the fracture toughness of such nanostructures is developed. This leads to the ability to propose plausible mechanisms for dislocation‐mediated fracture behavior in such small volumes.
The excess burden of stroke in hospitalized adults with sickle cell disease
Authors: Strouse John J. , Jordan Lori C. , Lanzkron Sophie , Casella James F.
Published: June 2009

This report compares the relative rates and risk factors associated with stroke in adults versus children with sickle cell disease (SCD) in the United States over the last decade. We identified incident strokes in patients with SCD using ICD‐9 codes for acute stroke and SCD and the California Patient Discharge Databases. We estimated SCD prevalence by using the incidence of SCD at birth with adjustment for early mortality from SCD. We identified 255 acute strokes (70 primary hemorrhagic and 185 ischemic) among 69,586 hospitalizations for SCD‐related complications from 1998 to 2007. The rate of stroke in children [<18 years old (310/100,000 person‐years)] was similar to young adults [18–34 years old (360/100,000 person‐years)], but much higher in middle‐aged [35–64 years old (1,160/100,000 person‐years)] and elderly adults [≥65 years old (4,700/100,000 person‐years)]. Stroke was associated with hypertension in children and hypertension, diabetes mellitus, hyperlipidemia, atrial fibrillation, and renal disease in adults. Most acute strokes (75%) and in‐hospital deaths from stroke (91%) occurred in adults. Our results suggest that the rate of stroke in SCD peaks in older adults and is three‐fold higher than rates previously reported in African‐Americans of similar age (35–64 years) without SCD. Stroke in SCD is associated with several known adult risk factors for ischemic and hemorrhagic stroke. Studies for the primary and secondary prevention of stroke in adults with SCD are urgently needed. Am. J. Hematol. 2009. © 2009 Wiley‐Liss, Inc.
Dopaminergic transplantation for parkinson's disease: Current status and future prospects
Authors: Olanow C. Warren , Kordower Jeffrey H. , Lang Anthony E. , Obeso Jose A.
Published: June 2009

Cell‐based therapies that involve transplantation into the striatum of dopaminergic cells have attracted considerable interest as possible treatments for Parkinson's disease (PD). However, all double‐blind, sham‐controlled, studies have failed to meet their primary endpoints, and transplantation of dopamine cells derived from the fetal mesencephalon is associated with a potentially disabling form of dyskinesia that persists even after withdrawal of levodopa (off‐medication dyskinesia). In addition, disability in advanced patients primarily results from features such as gait dysfunction, freezing, falling, and dementia, which are likely due to nondopaminergic pathology. These features are not adequately controlled with dopaminergic therapies and are thus unlikely to respond to dopaminergic grafts. More recently, implanted dopamine neurons have been found to contain Lewy bodies, suggesting that they are dysfunctional and may have been affected by the PD pathological process. Collectively, these findings do not bode well for the short‐term future of cell‐based dopaminergic therapies in PD. Ann Neurol 2009;66:591–596
Androgenic suppression of spreading depression in familial hemiplegic migraine type 1 mutant mice
Authors: Eikermann‐Haerter Katharina , Baum Michael J. , Ferrari Michel D. , van den Maagdenberg Arn M.J.M. , Moskowitz Michael A. , Ayata Cenk
Published: June 2009

Familial hemiplegic migraine type 1 (FHM1), a severe migraine with aura variant, is caused by mutations in the CACNA1A gene. Mutant mice carrying the FHM1 R192Q mutation exhibit increased propensity for cortical spreading depression (CSD), a propagating wave of neuroglial depolarization implicated in migraine aura. The CSD phenotype is stronger in female R192Q mutants and diminishes after ovariectomy. Here, we show that orchiectomy reciprocally increases CSD susceptibility in R192Q mutant mice. Chronic testosterone replacement restores CSD susceptibility by an androgen receptor‐dependent mechanism. Hence, androgens modulate genetically‐enhanced CSD susceptibility and may provide a novel prophylactic target for migraine. Ann Neurol 2009;66:564–568
Single‐cell expression profiling of dopaminergic neurons combined with association analysis identifies pyridoxal kinase as Parkinson's disease gene
Authors: Elstner Matthias , Morris Christopher M. , Heim Katharina , Lichtner Peter , Bender Andreas , Mehta Divya , Schulte Claudia , Sharma Manu , Hudson Gavin , Goldwurm Stefano , Giovanetti Alessandro , Zeviani Massimo , Burn David J. , McKeith Ian G. , Perry Robert H. , Jaros E. , Krüger Rejko , Wichmann H.‐Erich , Schreiber Stefan , Campbell Harry , Wilson James F. , Wright Alan F. , Dunlop Malcolm , Pistis Giorgio , Toniolo Daniela , Chinnery Patrick F. , Gasser Thomas , Klopstock Thomas , Meitinger Thomas , Prokisch Holger , Turnbull Douglass M.
Published: June 2009

Objective

The etiology of Parkinson disease (PD) is complex and multifactorial, with hereditary and environmental factors contributing. Monogenic forms have provided molecular clues to disease mechanisms but genetic modifiers of idiopathic PD are still to be determined.

Methods

We carried out whole‐genome expression profiling of isolated human substantia nigra (SN) neurons from patients with PD vs. controls followed by association analysis of tagging single‐nucleotide polymorphisms (SNPs) in differentially regulated genes. Association was investigated in a German PD sample and confirmed in Italian and British cohorts.

Results

We identified four differentially expressed genes located in PD candidate pathways, ie, MTND2 (mitochondrial, p = 7.14 × 10−7), PDXK (vitamin B6/dopamine metabolism, p = 3.27 × 10−6), SRGAP3 (axon guidance, p = 5.65 × 10−6), and TRAPPC4 (vesicle transport, p = 5.81 × 10−6). We identified a DNA variant (rs2010795) in PDXK associated with an increased risk of PD in the German cohort (p = 0.00032). This association was confirmed in the British (p = 0.028) and Italian (p = 0.0025) cohorts individually and reached a combined value of p = 1.2 × 10−7 (odds ratio [OR], 1.3; 95% confidence interval [CI], 1.18–1.44).

Interpretation

We provide an example of how microgenomic genome‐wide expression studies in combination with association analysis can aid to identify genetic modifiers in neurodegenerative disorders. The detection of a genetic variant in PDXK, together with evidence accumulating from clinical studies, emphasize the impact of vitamin B6 status and metabolism on disease risk and therapy in PD. Ann Neurol 2009;66:792–798
Fast Alkene Functionalization In Vivo by Photoclick Chemistry: HOMO Lifting of Nitrile Imine Dipoles
Authors: Wang Yizhong , Song Wenjiao , Hu Wen J. , Lin Qing
Published: June 2009

Äußerst schnell fluoreszenzmarkiert (<1 min) wurde ein rekombinantes Protein mit Alkenfunktion in Escherichia‐coli‐Zellen durch das Tetrazol 1. Der elektronenschiebende Methoxysubstituent hebt die Energie des höchsten besetzten Molekülorbitals des von 1 abgeleiteten Nitrilimin‐Intermediats an. Diese Strategie beschleunigt die Funktionalisierung von Alkenen in lebenden Systemen durch 1,3‐dipolare Cycloaddition erheblich.

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3 D Characterization of Gold Nanoparticles Supported on Heavy Metal Oxide Catalysts by HAADF‐STEM Electron Tomography
Authors: González J. C. , Hernández J. C. , López‐Haro M. , del Río E. , Delgado J. J. , Hungría A. B. , Trasobares S. , Bernal S. , Midgley P. A. , Calvino José Juan
Published: June 2009

Lieblingsplätze: Nach 3D‐Rekonstruktionen aus elektronentomographischen Daten, die an Au/Ce0.50Tb0.12Zr0.38O2−x‐Katalysatoren erhalten wurden, befinden sich Goldnanopartikel (gelb im Bild) vor allem an Stufen und Nanokristallgrenzen. Eine Epitaxiebeziehung zwischen Metall und Träger spielt für die strukturelle Stabilisierung der Goldnanopartikel eine entscheidende Rolle.

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A Highly Connected Porous Coordination Polymer with Unusual Channel Structure and Sorption Properties
Authors: Zhang Yue‐Biao , Zhang Wei‐Xiong , Feng Fei‐Yue , Zhang Jie‐Peng , Chen Xiao‐Ming
Published: June 2009

Stark vernetzt: Ein dreikerniger Nickelcluster, der eine zentrale Hydroxygruppe enthält, dient als Baustein für ein hoch vernetztes, hoch symmetrisches Gerüst mit uninodaler neunfach verknüpfender Topologie. Die von den Clustern abgeleiteten Triakistetraeder bilden ein überkreuzendes, biporöses Kanalsystem (siehe Bild).

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Fast Alkene Functionalization In Vivo by Photoclick Chemistry: HOMO Lifting of Nitrile Imine Dipoles
Authors: Wang Yizhong , Song Wenjiao , Hu Wen J. , Lin Qing
Published: June 2009

Extremely fast fluorescence labeling (<1 min) of a recombinant alkene‐encoded protein in living Escherichia coli cells was observed with tetrazole 1. The electron‐donating methoxy substituent raises the energy of the highest occupied molecular orbital of the nitrile–imine intermediate derived from 1. This strategy greatly accelerates the functionalization of alkenes by 1,3‐dipolar cycloaddition in living systems.

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3 D Characterization of Gold Nanoparticles Supported on Heavy Metal Oxide Catalysts by HAADF‐STEM Electron Tomography
Authors: González J. C. , Hernández J. C. , López‐Haro M. , del Río E. , Delgado J. J. , Hungría A. B. , Trasobares S. , Bernal S. , Midgley P. A. , Calvino José Juan
Published: June 2009

Living on the edge: Three‐dimensional reconstructions from electron tomography data recorded from Au/Ce0.50Tb0.12Zr0.38O2−x catalysts show that gold nanoparticles (see picture; yellow) are preferentially located on stepped facets and nanocrystal boundaries. An epitaxial relationship between the metal and support plays a key role in the structural stabilization of the gold nanoparticles.

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Application of carbon arc‐generated Mo‐ and W‐based catalyst systems to the ROMP of norbornene
Authors: Düz Bülent , Elbistan Can Koray , Ece Abdulilah , Sevin Fatma
Published: June 2009

This study focuses on the application of the carbon arc‐generated molybdenum‐ and tungsten‐based catalyst systems, MoCl5C and WCl6C, to effect ring‐opening metathesis polymerization (ROMP) of bicyclo[2.2.1]hept‐2‐ene (norbornene). The results are compared with those previously obtained by the electrochemically generated MoCl5ēAlCH2Cl2 and WCl6ēAlCH2Cl2 systems. The polymer products are characterized using 1H and 13C NMR, gel permeation chromatography, differential scanning calorimetry and thermo gravimetric analysis. According to NMR spectra analyses, the molybdenum‐based catalyst system produced polynorbornene with ca 48% cis structure whereas tungsten system produced ca 56% cis structure polynorbornene and in both cases the polynorbornene had a blocky distribution. Copyright © 2009 John Wiley & Sons, Ltd.
Polyimides derived from 1,4‐bis [3‐oxy‐(N‐aminophthalimide)] benzene
Authors: Li Taihang , Yan Jingling , Yang Huili , Li Dongfeng , Wang Zhen , Ding Mengxian
Published: June 2009

A novel diamine, 1,4‐bis [3‐oxy‐(N‐aminophthalimide)] benzene (BOAPIB), was synthesized from 1,4‐bis [3‐oxy‐(N‐phenylphthalimide)] benzene and hydrazine. Its structure was determined via IR, 1H NMR, and elemental analysis. A series of five‐member ring, hydrazine‐based polyimides were prepared from this diamine and various aromatic dianhydrides via one‐step polycondensation in p‐chlorophenol. The inherent viscosities of these polyimides were in the range of 0.17–0.61 dL/g. These polymers were soluble in polar aprotic solvents and phenols at room temperature. Thermogravimetric analysis (TGA) showed that the 5% weight‐loss temperatures of the polyimides were near 450°C in air and 500°C in nitrogen. Dynamic mechanical thermal analysis (DMTA) indicated that the glass‐transition temperatures (Tgs) of these polymers were in the range of 265–360°C. The wide‐angle X‐ray diffraction showed that all the polyimides were amorphous. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Preparation of P(AN‐MMA)/SiO2 hybrid solid electrolytes
Authors: Wang Hualin , Liu Xiaotao , Yu Shaoming , Shi Tiejun , Jiang Shaotong
Published: June 2009

Based on sol–gel methodology, poly(acrylonitrile‐methyl methacrylate) [P(AN‐MMA)[/SiO2 hybrid solid electrolytes were prepared from AN, MMA, and tetraethyl orthosilicate with 3‐methacryloxypropyl‐trimethoxysilane (KH570) as silane coupling agent. From Fourier transformed infrared spectroscopy and x‐ray photoelectron spectroscopy spectra, P(AN‐MMA) and silica units are linked by covalent bonds in P(AN‐MMA)/SiO2 hybrid network. Differential scanning calorimetry result shows the glass transition temperature (Tg) of P(AN‐MMA)/SiO2 hybrid material is higher than that of P(AN‐MMA) and increases with the increase of silica content. From X‐ray diffraction analysis, this hybrid solid electrolyte is amorphous. A study of ionic conductivity by AC impedance suggests that the ionic conductivity of P(AN‐MMA)/SiO2 hybrid solid electrolyte increases with the increase of the silica content and reaches a maximum value of 1.42 × 10−3 S cm−1 for 7 wt % SiO2, and then decreases for SiO2 > 7 wt %. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Glass fiber‐reinforced composite based on benzoxazine resin
Authors: Kimura Hajime , Matsumoto Akihiro , Ohtsuka Keiko
Published: June 2009

In this study, we aimed to prepare and characterize glass fiber‐reinforced composites (GFRP) based on benzoxazine resins. Therefore, the molten resin from benzoxazine and bisoxazoline with the latent curing agent was used as the matrix resin, and the properties of GFRP based on the molten resins were investigated. The properties of GFRP were estimated by mechanical properties, heat resistance, and flame resistance. As a result, it was found that GFRP based on the molten resins from benzoxazine and bisoxazoline with the latent curing agent showed good heat resistance, flame resistance, and mechanical properties compared with those of the conventional GFRP. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Surface properties of poly(ethylene oxide)‐based segmented block copolymers with monodisperse hard segments
Authors: Husken D. , Feijen Jan , Gaymans R. J.
Published: June 2009

The surface properties of segmented block copolymers based on poly(ethylene oxide) (PEO) segments and monodisperse crystallizable tetra‐amide segments were studied. The monodisperse crystallizable segments (T6T6T) were based on terephthalate (T) and hexamethylenediamine (6). Due to the crystallinity of T6T6T being high (∼ 85%), the amount of amorphous T6T6T dissolved in the polyether phase was limited. The length of the PEO segments was varied (between 600 and 4600 g/mol) and effect of extending the PEO segments with terephthalic groups was investigated. Studied was the hydrophilicity of the surface by contact angle measurements and of the bulk copolymers by water absorption measurements The results were compared with data of PEO‐poly(butylene terephthalate) (PEO‐PBT) copolymers. For a given hydrophilicity of the bulk copolymer, the surface hydrophilicity decreased in the order PEO‐PBT, PEO‐T6T6T, and (PEO‐T)‐T6T6T. The use of short monodisperse hard segments resulted in low contact angles, with a lowest observed value of ∼ 29°. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Preparation of Zr4+ affinity column by atom transfer radical polymerization for phosphoprotein isolation
Authors: Park Jung‐Hyun , Bae In‐Ae , Choi Seong‐Ho
Published: June 2009

This paper describes the preparation of the metallic affinity column by atom transfer radical polymerization of glycidyl methacrylate (GMA) on Wang resin surface. The metallic ions (Zr4+, Fe3+, and Pd2+) were introduced after phosphonation of the epoxy group of the grafted poly(GMA) on Wang resin surface. The successful results on metallic ion‐immobilized polymeric microsphere stationary phase were confirmed via Fourier transform infrared, scanning electron microscopy, X‐ray photoelectron spectra (XPS), and inductively coupled plasma‐atomic emission spectrometer. The resolution degree of the phosphonated casein and dephosphonated casein for Zr4+, Fe3+, and Pd2+ affinity column was examined. The result shows that the resolution time (min) of the phosphonated casein was higher than that of the dephosphated casein on the Zr4+ affinity column by liquid chromatography. However, the phosphonated casein and dephosphonated casein were not separated on the Fe3+ affinity column and Pd2+ affinity column by liquid chromatography. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Sodium alginate/Na+‐rectorite composite films: Preparation, characterization, and properties
Authors: Yang Lianli , Liang Guozheng , Zhang Zengping , He Shaobo , Wang Jinhe
Published: June 2009

Rectorite (REC), one kind of layered silicates, has been applied to polymers to improve their properties. The sodium alginate (SA) layered silicate is a new option to modify the properties of polysaccharides. In this article, SA was modified by Na+‐rectorite (Na+REC). The chemical structures and microstructures of Na+REC and Na+REC modified SA (SA/Na+REC) were analyzed by using Fourier transform infrared spectrometer and X‐ray diffraction. The morphologies of SA/Na+REC composites were observed by using scanning electron microscopy and transmission electron microscopy. The mechanical and anti‐ultraviolet properties as well as thermal properties of SA/Na+REC composites were investigated. The results show that the properties of pure SA film can be improved by the addition of Na+REC, and SA/Na+REC composite containing 2 wt % Na+REC has the best intercalation effect and optimum comprehensive properties among the prepared composites in this article. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Refolding of lysozyme in vitro assisted by colloidal thermosensitive poly(N‐isopropylacrylamide) brushes grafted onto the surface of uniform polystyrene cores
Authors: Ge Xiang , Guan Yi‐Xin , Chen Jie , Yao Zhen , Cao Kun , Yao Shan‐Jing
Published: June 2009

The renaturation of lysozyme assisted by a novel type of hairy particles was investigated. The particles used consisted of polystyrene (PS) cores onto which long chains of thermosensitive poly(N‐isopropylacrylamide) (PNIPAM) were grafted as shell. Here, two kinds of particles were synthesized as sub‐micron PS cores and 89 nm brush thickness (Particle A) and 122 nm brush thickness (Particle B), respectively. Thermosensitive characteristics of the above prepared hairy uniform PS particles with PNIPAM brushes were studied and the results indicated that the lower critical solution temperature (LCST) of PNIPAM brushes grafted on the surface of uniform PS cores was between 33 and 34°C. It was proved that the particles were quite efficient in assisting lysozyme renaturation at high initial protein concentration. When the protein concentration was increased to 500 μg/mL, the refolding yield of the recovery of lysozyme activity could achieve 58.0% (Particle A) and 71.5% (Particle B), compared with only 34.8% by simple dilution refolding. Furthermore, the kinetics of lysozyme refolding in the absence and the presence of the colloidal particles were studied accordingly. The results indicated that the time required for the refolding with colloidal particles was a little bit delayed than that by the simple dilution method owing to the hydrophobic interactions between lysozyme and the PNIPAM brushes. The mechanism of the enhancement for the hairy uniform PS particles with PNIPAM brushes assisted refolding was further discussed. All results above demonstrated that the spherical PNIPAM brushes presented an alternative way to assist protein renaturation in vitro.© 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Interactions between cationic conjugated polyelectrolyte and DNA and a label‐free method for DNA detection based on conjugated polyelectrolyte complexes
Authors: Song Heng , Sun Bin , Gu Ke‐Jun , Yang Yan , Zhang Yang , Shen Qun‐Dong
Published: June 2009

The electrostatic complexes of single‐stranded deoxyribonucleic acid (ssDNA) and a cationic conjugated polyelectrolyte (CPE), poly{9,9‐di[3‐(1‐ethyl‐1,1‐dimethyl ammonio)propyl]‐2,7‐fluorenyl‐alt‐1,4‐phenylene dibromide} (PFN), were investigated. Fluorescence emission of PFN solution (10 μmol/L) can be drastically quenched to about one fourth of its original intensity in the presence of a trace amount (2.6 μmol/L) of ssDNA. The effect of oligonucleotide length on the fluorescence quenching behavior was also investigated. In contrast to single‐stranded DNA with 20 bases (ssDNA‐20), ssDNA with 40 bases (ssDNA‐40) induces a relatively higher quenching efficiency and larger red‐shift of PFN emission maximum. The binding constant of ssDNA‐20 and PFN is estimated to be 1.12 × 1021. At extremely low concentration (10 nmol/L), PFN can respond to 0.2 nmol/L (or 2 × 10−10 mol/L) of ssDNA‐20 by significant enhancement of its emission intensity. The result is contrary to the observation in the relative higher concentration, and its mechanism is postulated. Based on the high binding ability of ssDNA with cationic CPE, a label‐free method for ssDNA detection is designed. It uses an electrostatic complex of cationic PFN and an anionic CPE, which exhibits fluorescence resonance energy transfer (FRET) between the two components. Addition of ssDNA improves the FRET extent, indicated by obvious change of fluorescence spectra of the conjugated polyelectrolyte complex. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Effect of orotic acid as a nucleating agent on the crystallization of bacterial poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) copolymers
Authors: Jacquel Nicolas , Tajima Koichirou , Nakamura Nobuo , Miyagawa Toshio , Pan Pengju , Inoue Yoshio
Published: June 2009

The kinetics of crystallization induced by orotic acid (OA) and boron nitride (BN) as nucleating agents were investigated for bacterial poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate)s (P(HB‐co‐HH)s) containing from 0 to 18% HH monomer units. The nucleation efficiency of these two chemicals was investigated by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). It was found that both orotic acid and boron nitride are able to nucleate the crystallization of PHB. In the case of P(HB‐co‐HH) copolymers, orotic acid showed an outstanding nucleating effect. The comparison of half‐crystallization times shows that for P(HB‐co‐10% HH), the crystallization initiated by orotic acid is more than three time faster than the one induced by boron nitride (t1/2BN/t1/2OA(60°C) = 3.7 and t1/2BN/t1/2OA(90°C) = 4.5). According to the fact that orotic acid is a biodegradable, biocompatible and a nontoxic chemical, this nucleating agent is a promising solution for PHAs used in medical applications such as implants. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Preparation and properties of flame retardant poly(urethane‐imide)s containing phosphine oxide moiety
Authors: Özarslan Özdemir , Bayazıt Mustafa Kemal , Çatıker Efkan
Published: June 2009

The preparation of new poly(urethane‐imide)s (PUIs) having acceptable thermal stability and higher flame resistance was aimed. Two new aromatic diisocyanate‐containing methyldiphenylphosphine oxide and triphenylphosphine oxide moieties were synthesized via Curtius rearrangement in situ and polymerized by various prepared diols. Four aliphatic hydroxy terminated aromatic based diols were synthesized by the reaction between ethylene carbonate and various diphenolic substances. Chemical structures of monomers and polymers were characterized by FTIR, 1H NMR, 13C NMR, and 31P NMR spectroscopy. Thermal stabilities and decomposition behaviors of the PUIs were tested by DSC and TGA. Thermal measurements indicate that the polymers have high thermal stability and produce high char. Polymers exhibit quite high fire resistance, evaluated by fire test UL‐94. The films of the polymers were prepared by casting the solution. Inherent viscosities, solubilities, and water absorbtion behaviors of the polymers were reported in. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Characterization and comparison of Acetosolv and Milox lignin isolated from crofton weed stem
Authors: Zhao Xuebing , Dai Lingmei , Liu Dehua
Published: June 2009

Crofton weed (Eupatorium adenophorum Spreng) is an invasive species in China, which has damaged native ecosystems and caused great economic losses. To use the weed instead of simple control and management of it, the weed stem of was delignified by Acetosolv and Milox processes to obtain lignin. The lignins (Acetosolv lignin, AL; and Milox lignin, ML) were characterized and compared through several analysis methods. It was found that both of AL and ML were syringyl‐guaiacyl type (GS) lignin, but that the chemical composition and structure of the two lignins were somewhat different. The obtained C9 expanded formulas for AL and ML were C9H9.16O3.50N0.13(OCH3)0.97(PhOH)0.34Ac0.22 and C9H7.96O3.13N0.13(OCH3)1.23(PhOH)0.51Ac0.14, respectively. According to an elementary analysis, the two lignins had similar higher heat value of 20.0–21.0 MJ kg−1, which were similar to that of raw coal. Gel permeation chromatography analysis indicated the two lignins had similar molecular weights. Notwithstanding that the Ultraviolet, Fourier transform infrared, and 1H‐NMR spectra illustrated that the two lignins had similar chemical functional groups, the AL showed more acetyl groups signals. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Structure and properties of hemp fabric treated with chitosan and dyed with mixed epoxy‐modified silicone oil
Authors: Zhang H. , Zhang L. M.
Published: June 2009

To enhance the color yield and improve the soft handle, hemp fabrics were treated with chitosan of molecular weight 4200 and degree of deacetylation 0.90, and then dyed using Remazol Brillant Blue R with mixed epoxy‐modified silicone oil in different volume ratios. The structural changes in hemp fibers were investigated by means of scanning electron microscope, FTIR, TG, DSC, and XRD. The properties of tensile, bending, dyeing, and color fastness for hemp fabric were also studied. The results showed that when compared with the untreated hemp fiber, the thermal performance of chitosan/silicone oil‐modified hemp fiber changed and the percent residual weight increased in the range of temperature 25–550°C. The crystal grain size decreased and the degree of crystallization increased. For chitosan/silicone oil‐treated hemp fabric, the flexural stiffness and tensile properties degraded. The maximum color yield (K/S value) was obtained when the volume ratio of dyeing liquor to silicone oil was 2 : 1. The color fastnesses to rubbing and wet scrubbing were also improved. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Crystallization behavior and UV‐protection property of PET‐ZnO nanocomposites prepared by in situ polymerization
Authors: He Junqing , Shao Wei , Zhang Ling , Deng Chao , Li Chunzhong
Published: June 2009

The aim of this study was to investigate the crystallization behavior and UV‐protection property of polyethylene terephthalate (PET)‐ZnO nanocomposits. PET‐ZnO nanocomposites containing 0.5–3.0 wt % of ZnO were successfully synthesized by in situ polymerization. The Fourier transformed infrared (FTIR) spectroscopy indicated the silane coupling agent was anchored onto the surface of ZnO. Scanning electron microscope (SEM) images showed ZnO particles were dispersed homogeneously in PET matrix with amount of 0.5–1.0 wt %. Differential scanning calorimetry (DSC) results exhibited that the incorporation of ZnO into PET resulted in increase of the melting transition temperature (Tm) and crystallization temperature (Tc) of PET‐ZnO nanocomposites. The crystallization behavior of PET and PET‐ZnO nanocomposites was strongly affected by cooling rate. ZnO nanoparticles can act as an efficient nucleating agent to facilitate PET crystallization. UV–vis spectrophotometry showed that UV‐ray transmittance of PET‐ZnO nanocomposites decreased remarkably and reached the minimum value of 14.3% with 1.5 wt % of ZnO, compared with pure PET whose UV‐ray transmittance was 84.5%. PET‐ZnO nanocomposites exhibited better UV‐protection property than pure PET, especially in the range of UVA. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Polymer crystallization and precipitation‐induced wrapping of carbon nanofibers with PBT
Authors: Mago Gaurav , Kalyon Dilhan M. , Fisher Frank T.
Published: June 2009

Carbon nanofibers (CNFs) have attracted significant interest because of their excellent mechanical, electrical, and physical properties. Recent advances in chemical functionalization strategies are anticipated to extend their utility in various applications. In this study, noncovalent methods of CNF functionalization utilizing solution crystallization and precipitation techniques were used to create hybrid nanostructures consisting of CNFs and poly(butylene terephthalate) (PBT). Key to this study is the finding thato‐chlorophenol can be used as a suitable solvent to dissolve PBT to generate these nanostructures. PBT crystallization was documented via wide‐angle X‐ray analysis and differential scanning calorimetry and was due to the nucleation effect of the CNFs. The sizes of the PBT crystals could be manipulated by altering the polymer concentration. The solution crystallization and precipitation techniques provide an alternative strategy to alter and control the nanostructure/polymer interface. The resulting nanohybrid structures may potentially find use in a broad range of applications including electronic devices, sensors, and as reinforcing agents in a polymer matrix. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009