bluuebunny/crossref_metadata_2025 huggingface dataset:
Microscopic Diffusion Dynamics of Silver Complex‐Based Room‐Temperature Ionic Liquids Probed by Quasielastic Neutron Scattering
Authors: Mamontov Eugene , Baker Gary A. , Luo Huimin , Dai Sheng
Published: March 2011

Quasielastic neutron scattering is used to probe the microscopic diffusion dynamics of the hydrogen‐bearing cations of two different silver complex‐derived room‐temperature ionic liquids, [Ag(propylamine)2+][Tf2N−] (Tf=trifluoromethanesulfonyl) and [Ag(1‐pentene)+][Tf2N−]. In the temperature range from 300 to 340 K, analysis of the scattering momentum transfer dependence of the data provides evidence for three distinct diffusion components. The slowest component describes the long‐range cationic translational diffusion. A possible link between the microscopic diffusion parameters and the structural features of the cations comprising these two ionic liquids is discussed.
Interaction of Inorganic Nanoparticles with Graphene
Authors: Das Barun , Choudhury Biswajit , Gomathi A. , Manna Arun K. , Pati S. K. , Rao C. N. R.
Published: March 2011

The changes in the electronic and magnetic properties of graphene induced by interaction with semiconducting oxide nanoparticles such as ZnO and TiO2 and with magnetic nanoparticles such as Fe3O4, CoFe2O4, and Ni are investigated by using Raman spectroscopy, magnetic measurements, and first‐principles calculations. Significant electronic and magnetic interactions between the nanoparticles and graphene are found. The findings suggest that changes in magnetization as well as the Raman shifts are directly linked to charge transfer between the deposited nanoparticles and graphene. The study thus demonstrates significant effects in tailoring the electronic structure of graphene for applications in futuristic electronic devices.
Steady state migratory RelB+ langerin+ dermal dendritic cells mediate peripheral induction of antigen‐specific CD4+CD25+Foxp3+ regulatory T cells
Authors: Azukizawa Hiroaki , Döhler Anja , Kanazawa Nobuo , Nayak Arnab , Lipp Martin , Malissen Bernard , Autenrieth Ingo , Katayama Ichiro , Riemann Marc , Weih Falk , Berberich‐Siebelt Friederike , Lutz Manfred B.
Published: March 2011

Tolerance to self‐antigens expressed in peripheral organs is maintained by CD4+ CD25+ Foxp3+ Treg cells, which are generated as a result of thymic selection or peripheral induction. Here, we demonstrate that steady‐state migratory DCs from the skin mediated Treg conversion in draining lymph nodes of mice. These DCs displayed a partially mature MHC IIint CD86int CD40hi CCR7+ phenotype, used endogenous TGF‐β for conversion and showed nuclear RelB translocation. Deficiency of the alternative NF‐κB signaling pathway (RelB/p52) reduced steady‐state migration of DCs. These DCs transported and directly presented soluble OVA provided by s.c. implanted osmotic minipumps, as well as cell‐associated epidermal OVA in transgenic K5‐mOVA mice to CD4+ OVA‐specific TCR‐transgenic OT‐II T cells. The langerin+ dermal DC subset, but not epidermal Langerhans cells, mediated conversion of naive OT‐II×RAG‐1−/− T cells into proliferating CD4+ CD25+ Foxp3+ Tregs. Thus, our data suggest that steady‐state migratory RelB+ TGF‐β+ langerin+ dermal DCs mediate peripheral Treg conversion in response to epidermal antigen in skin‐draining lymph nodes.
In vivo diabetogenic action of CD4+ T lymphocytes requires Fas expression and is independent of IL‐1 and IL‐18
Authors: Wen Li , Green Elizabeth A. , Stratmann Thomas , Panosa Anaïs , Gomis Ramon , Eynon Elizabeth E. , Flavell Richard A. , Mezquita Jovita A. , Mora Conchi
Published: March 2011

CD4+ T lymphocytes are required to induce spontaneous autoimmune diabetes in the NOD mouse. Since pancreatic β cells upregulate Fas expression upon exposure to pro‐inflammatory cytokines, we studied whether the diabetogenic action of CD4+ T lymphocytes depends on Fas expression on target cells. We assayed the diabetogenic capacity of NOD spleen CD4+ T lymphocytes when adoptively transferred into a NOD mouse model combining: (i) Fas‐deficiency, (ii) FasL‐deficiency, and (iii) SCID mutation. We found that CD4+ T lymphocytes require Fas expression in the recipients' target cells to induce diabetes. IL‐1β has been described as a key cytokine involved in Fas upregulation on mouse β cells. We addressed whether CD4+ T cells require IL‐1β to induce diabetes. We also studied spontaneous diabetes onset in NOD/IL‐1 converting enzyme‐deficient mice, in NOD/IL‐1β‐deficient mice, and CD4+ T‐cell adoptively transferred diabetes into NOD/SCID IL‐1β‐deficient mice. Neither IL‐1β nor IL‐18 are required for either spontaneous or CD4+ T‐cell adoptively transferred diabetes. We conclude that CD4+ T‐cell‐mediated β‐cell damage in autoimmune diabetes depends on Fas expression, but not on IL‐1β unveiling the existing redundancy regarding the cytokines involved in Fas upregulation on NOD β cells in vivo.
Triazolyl Derivatives for Acidic Release of Alcohols
Authors: Mondon Martine , Delatouche Régis , Bachmann Christian , Frapper Gilles , Len Christophe , Bertrand Philippe
Published: March 2011

New triazolyl‐based carbonates and ethers have been investigated as potential alcohol‐releasing systems under mild acidic conditions. Triazolyl carbonates could not be prepared because of their apparent instability, whereas ethers were successfully obtained. The rate of hydrolysis of these ethers ramged from a few hours to several days. A theoretical investigation demonstrated that the acidic release of alcohols from triazole derivatives proceeds first by protonation of the triazole ring followed by proton transfer from the triazole ring to the carbonyl group of the carbonates or to the oxygen atom of the ether derivatives. The rate of the decomposition reaction was shown to depend on the length of the N3–H···O hydrogen bond in the intermediate C‐NH+/E‐NH+ structures and on the stability of the triazole carbocation, which is closely related to the π‐donating effect of its R2 and R3 substituents.
Community‐based research on the effectiveness of the home smoke alarm in waking up children
Authors: Bruck D. , Thomas I. R.
Published: March 2011

This project targeted parents around Australia asking them to set off their home smoke alarm when their child was asleep and enter the results onto a special web site. The main aim was to determine the likelihood of children waking up under the same alarm conditions as would apply on a typical night at home. Valid data were collected for 123 children (60 M, 63 F, ages 5–15 years). Recruitment was done entirely via the media and postcards. Parents set off the smoke alarm closest to the child's bed for 30thinspaces, 1–3 h after sleep onset and 78% slept through the alarm. Younger children (5–10 years) were significantly more at risk, with 87% sleeping through, compared with 56% of 11–15‐year olds. Of the 27 children who woke up, 61% knew that the sound that woke them was a smoke alarm and 47% indicated that they knew they should leave the house. Our previous research suggests that some 5–10% more children may wake up if the alarm continues for 3 min. This study, consistent with previous less naturalistic studies, suggests that less than a third of children may wake up to their home smoke alarm within 3 min. Copyright © 2011 John Wiley & Sons, Ltd.
Second-phase hepatitis C virus RNA decline during telaprevir-based therapy increases with drug effectiveness: Implications for treatment duration
Authors: Guedj Jeremie , Perelson Alan S.
Published: March 2011

Hepatitis C virus (HCV) RNA decay during antiviral therapy is characterized by a rapid first phase, followed by a slower second phase. The current understanding of viral kinetics attributes the magnitude of the first phase of decay to treatment effectiveness, whereas the second phase of decay is attributed to the progressive loss of infected cells. Here, we analyzed data from 44 patients treated with telaprevir, a potent HCV protease inhibitor. Using a viral kinetic model that accounts for the pharmacokinetics of telaprevir, we found the second-phase slope of viral decline to be strongly correlated with treatment effectiveness and to be roughly four-fold more rapid than has been reported with interferon-based therapies. Because telaprevir is not known to increase the death rate of infected cells, our results suggest that the second-phase slope of viral decline is driven not only by the death of infected cells, but may also involve other mechanisms, such as a treatment-effectiveness–dependent degradation of intracellular viral RNA. As a result of the enhanced viral decay caused by the high antiviral effectiveness of telaprevir, we predict that if drug resistance could be avoided by using an appropriate combination of antiviral agents, treatment duration needed to clear HCV might be dramatically shortened. Indeed, we predict that in 95% of fully compliant patients, the last virus particle should be eliminated by week 7 of therapy. If the remaining infected hepatocytes act as a potential reservoir for the renewal of infection, no more than 10 weeks of treatment should be sufficient to clear the infection in 95% of fully compliant patients. However, if patients miss doses, treatment duration would need to be extended. (HEPATOLOGY 2011;)
Hypermagnesemia does not prevent intracranial hypertension and aggravates cerebral hyperperfusion in a rat model of acute hyperammonemia
Authors: Bjerring Peter Nissen , Eefsen Martin , Larsen Fin Stolze , Bernal William , Wendon Julia
Published: March 2011

Intravenous infusion of magnesium sulfate prevents seizures in patients with eclampsia and brain edema after traumatic brain injury. Neuroprotection is achieved by controlling cerebral blood flow (CBF), intracranial pressure, neuronal glutamate release, and aquaporin-4 (Aqp4) expression. These factors are also thought to be involved in the development of brain edema in acute liver failure. We wanted to study whether hypermagnesemia prevented development of intracranial hypertension and hyperperfusion in a rat model of portacaval anastomosis (PCA) and acute hyperammonemia. We also studied whether hypermagnesemia had an influence on brain content of glutamate, glutamine, and aquaporin-4 expression. The study consisted of three experiments: The first was a dose-finding study of four different dosing regimens of magnesium sulfate (MgSO4) in healthy rats. The second involved four groups of PCA rats receiving ammonia infusion/vehicle and MgSO4/saline. The effect of MgSO4 on mean arterial pressure (MAP), intracranial pressure (ICP), CBF, cerebral glutamate and glutamine, and aquaporin-4 expression was studied. Finally, the effect of MgSO4 on MAP, ICP, and CBF was studied, using two supplementary dosing regimens. In the second experiment, we found that hypermagnesemia and hyperammonemia were associated with a significantly higher CBF ( P < 0.05, two-way analysis of variance [ANOVA]). Hypermagnesemia did not lead to a reduction in ICP and did not affect the brain content of glutamate, glutamine, or Aqp-4 expression. In the third experiment, we achieved higher P-Mg but this did not lead to a significant reduction in ICP or CBF.

Conclusion:

Our results demonstrate that hypermagnesemia does not prevent intracranial hypertension and aggravates cerebral hyperperfusion in rats with PCA and hyperammonemia. (HEPATOLOGY 2011;)
The contribution of endoplasmic reticulum stress to liver diseases
Authors: Dara Lily , Ji Cheng , Kaplowitz Neil
Published: March 2011

The unfolded protein response (UPR) is an evolutionarily conserved cell signaling pathway that is activated to regulate protein synthesis and restore homeostatic equilibrium when the cell is stressed from increased client protein load or the accumulation of unfolded or malfolded proteins. Once activated, this signaling pathway can either result in the recovery of homeostasis or can activate a cascade of events that ultimately result in cell death. The UPR/endoplasmic reticulum (ER) stress response spectrum and its interplay with other cellular organelles play an important role in the pathogenesis of disease in secretory cells rich in ER, such as hepatocytes. Over the past 2 decades, the contribution of ER stress to various forms of liver diseases has been examined. Robust support for a contributing, as opposed to a secondary role, for ER stress response is seen in the nonalcoholic steatohepatitis, alcoholic liver disease, ischemia/reperfusion injury, and cholestatic models of liver disease. The exact direction of the cause and effect relationship between modes of cell injury and ER stress remains elusive. It is apparent that a complex interplay exists between ER stress response, conditions that promote it, and those that result from it. A vicious cycle in which ER stress promotes inflammation, cell injury, and steatosis and in which steatogenesis, inflammation, and cell injury aggravate ER stress seems to be at play. It is perhaps the nature of such a vicious cycle that is the key pathophysiologic concept. Therapeutic approaches aimed at interrupting the cycle may dampen the stress response and the ensuing injury. (hepatology 2011;)
The nicotinamide adenine dinucleotide phosphate oxidase (NOX) homologues NOX1 and NOX2/gp91phox mediate hepatic fibrosis in mice
Authors: Paik Yong-Han , Iwaisako Keiko , Seki Ekihiro , Inokuchi Sayaka , Schnabl Bernd , Österreicher Christoph H. , Kisseleva Tatiana , Brenner David A.
Published: March 2011

Nicotinamide adenine dinucleotide phosphate oxidase (NOX) is a multicomponent enzyme that mediates electron transfer from nicotinamide adenine dinucleotide phosphate to molecular oxygen, which leads to the production of superoxide. NOX2/gp91phox is a catalytic subunit of NOX expressed in phagocytic cells. Several homologues of NOX2, including NOX1, have been identified in nonphagocytic cells. We investigated the contributory role of NOX1 and NOX2 in hepatic fibrosis. Hepatic fibrosis was induced in wild-type (WT) mice, NOX1 knockout (NOX1KO) mice, and NOX2 knockout (NOX2KO) mice by way of either carbon tetrachloride (CCl4) injection or bile duct ligation (BDL). The functional contribution of NOX1 and NOX2 in endogenous liver cells, including hepatic stellate cells (HSCs), and bone marrow (BM)-derived cells, including Kupffer cells (KCs), to hepatic reactive oxygen species (ROS) generation and hepatic fibrosis was assessed

in vitro

and

in vivo

using NOX1 or NOX2 BM chimeric mice. Hepatic NOX1 and NOX2 messenger RNA expression was increased in the two experimental mouse models of hepatic fibrosis. Whereas NOX1 was expressed in HSCs but not in KCs, NOX2 was expressed in both HSCs and KCs. Hepatic fibrosis and ROS generation were attenuated in both NOX1KO and NOX2KO mice after CCl4 or BDL. Liver fibrosis in chimeric mice indicated that NOX1 mediates the profibrogenic effects in endogenous liver cells, whereas NOX2 mediates the profibrogenic effects in both endogenous liver cells and BM-derived cells. Multiple NOX1 and NOX2 components were up-regulated in activated HSCs. Both NOX1- and NOX2-deficient HSCs had decreased ROS generation and failed to up-regulate collagen α1(I) and transforming growth factor β in response to angiotensin II.

Conclusion:

Both NOX1 and NOX2 have an important role in hepatic fibrosis in endogenous liver cells, including HSCs, whereas NOX2 has a lesser role in BM-derived cells. (Hepatology 2011;)
Identification of the most influential factors in the Norwegian guidelines for risk assessment of dispersion of contaminants from sediments
Authors: Saloranta Tuomo M , Ruus Anders , Borgå Katrine
Published: March 2011

The Norwegian guidelines for risk assessment of contaminated sediments are used to identify areas of concern where remediation may be needed to meet the governmental long-term goal of clean fjords and harbors along the Norwegian coastline. By a thorough sensitivity analysis, this study identifies the most influential factors and parameters for the Tier 2A model in this risk guideline, which are used to estimate fluxes of contaminants from sediments due to diffusion and bioturbation (Fdiff), resuspension caused by ship traffic (Fskipnorm), and uptake and predation of benthic biota (Forg). The sensitivity analysis is run for 36 different scenarios combining 3 different sizes of contaminated area, 3 harbor types, and 3 persistent organic pollutants, namely lindane (γ-hexachlorocyclohexane), benzo[a]pyrene, and 2,2′,4,4′,5,5′-hexachlorobiphenyl (PCB-153), as well as the metal mercury (Hg). The most influential parameters vary from scenario to scenario, but generally 5 parameters appear to be particularly influential for the fluxes and transport estimated by the Tier 2A model: flux of organic carbon to sediment (OCsed), factor for increased diffusion due to bioturbation (a), sediment–water partitioning coefficient (Kd), benthic biota–water bioconcentration factor (BCFfisk), and mass of resuspended fine sediment during arrival or departure of a ship (msed). We also quantify which of the 3 fluxes (Fdiff, Fskipnorm, and Forg) dominate in the different scenarios. Our sensitivity analysis results can be used by authorities, problem owners, consultants, and environmental managers involved in contaminated sediment management to gain insight on the key processes and parameters and to focus their site-specific or laboratory-based measurement efforts on the key parameters and thus increase efficiency and reliability in the contaminated sediment risk assessment. Integr Environ Assess Manag 2011;7:657–667. © 2011 SETAC
Synthesis of new 1‐phenylthieno[1,2,4]triazolo[4,3‐a]pyrimidin‐5(4H)‐one derivatives
Authors: Song Yang‐Heon , Son Hoon Young
Published: March 2011

A series of novel 1‐phenylthieno[1,2,4]triazolo[4,3‐a]pyrimidin‐5(4H)‐one derivatives 5 and 6 were synthesized by oxidative cyclization of thienopyrimidinonyl hydrazones using iodobenzene diacetate. J. Heterocyclic Chem., (2011).
Ten marker compounds‐based comparative study of green tea and guava leaf by HPTLC densitometry methods: Antioxidant activity profiling
Authors: Khan Imran , Sangwan Payare L. , Abdullah Sheikh Tasduq , Gupta Bhisan D. , Dhar Jagdish K. , Manickavasagar Rajendran , Koul Surrinder
Published: March 2011

High‐performance thin layer chromatography (HPTLC) method for the separation and quantitative determination of ten markers (catechins, flavonoids, and phenolics) in different extracts of green tea and guava leaf has been developed and the antioxidant activity profiles of the two plant extracts have been determined. Ten marker compounds have been resolved using silica gel 60 F254 plates, toluene/acetone/formic acid (5:4:1 v/v/v) for markers 1–6, and toluene/ethyl acetate/formic acid/methanol (3:3:0.8:0.2 v/v/v/v) for markers 7–10 as the mobile phases. The high‐performance thin layer chromatography densitometry was performed at wavelengths of 282 and 285 nm for the markers 1–6 and 7–10, respectively. Potent antioxidant activity and the presence of phenolics and flavan‐3‐ols has been observed for the guava leaf extracts suggestive of its use as an alternate economical source of antioxidants over green tea – the well‐established food additive/nutraceutical agent.
Adherence in Liver Transplant Recipients
Authors: Burra Patrizia , Germani Giacomo , Gnoato Francesca , Lazzaro Silvia , Russo Francesco Paolo , Cillo Umberto , Senzolo Marco
Published: March 2011

Adherence to a medical regimen has been defined as the extent to which a patient's behavior coincides with clinical prescriptions. In liver transplant patients, adherence to immunosuppressive therapy and to medical indications in general is crucial for short- and long-term outcomes. Nonadherence to immunosuppression carries a risk of graft rejection and potential graft loss, whereas nonadherence to general medical indications (eg, avoiding alcohol intake and smoking after transplantation) may be associated with other complications such as de novo tumors and increasing health care costs. Among adult liver transplant patients, the rate of nonadherence to immunosuppressive drugs ranges from 15% to 40%, whereas the rate of nonadherence to clinical appointments ranges from 3% to 47%. The wide range of reported rates is due to different definitions of the term nonadherence and the variety of methods used to measure adherence in the medical literature. Nonadherence seems to be nearly 4 times higher in pediatric and adolescent patients versus adult transplant recipients. Several nonadherence risk factors, such as high medication costs, psychiatric disorders, the conviction that the medication is harmful, and side effects of immunosuppressive therapy, have been described among adult liver transplant patients. The risk factors for nonadherence in pediatric and adolescent liver transplant patients are psychological distress, the functional status of their families, and the impact of immunosuppressive side effects on their physical appearance. A single approach to promoting adherence to general medical prescriptions has been proved to be ineffectual, so a multidisciplinary strategy should be adopted to achieve significant improvements in this field. The aim of this review is to analyze the published literature on adherence in liver transplant patients with a particular focus on the reported prevalence and the identified risk factors. Patients have been split into 2 age groups (adults and children/adolescents) because the scale of the problem and the potential risk factors differ in the 2 groups. Liver Transpl 17:760-770, 2011. © 2011 AASLD.
Characterisation of the Chemical Composition Distribution of LLDPE Using Interactive Liquid Chromatography
Authors: Dolle Volker , Albrecht Andreas , Brüll Robert , Macko Tibor
Published: March 2011

It is demonstrated that copolymers of ethylene with higher 1‐olefins can be separated using bare silica gel as the stationary phase and a gradient of ethylene glycol monobutyl ether and 1,2,4‐trichlorobenzene as the mobile phase at 160 °C. The separation of ethylene 1‐hexene copolymers according to their composition is confirmed by linking the chromatographic separation to infrared spectroscopy. Using well‐characterised model fractions from temperature rising elution fractionation or solvent/non‐solvent fractionation (“Holtrup”), it can be shown that both the content and type of the comonomer mainly govern the elution in two peaks which differ in their comonomer content. The molar mass only plays a subordinate rule.

magnified image
Improving the Stability in Aqueous Media of Polymer Brushes Grafted from Silicon Oxide Substrates by Surface‐Initiated Atom Transfer Radical Polymerization
Authors: Paripovic Dusko , Klok Harm‐Anton
Published: March 2011

Hydrophilic polymer brushes grown via surface‐initiated ATRP from silicon oxide surfaces are susceptible to detachment via hydrolytic cleavage of the anchoring siloxane bond. This paper investigates the influence of the structure of the ATRP initiator on the stability of these brushes and seeks for strategies to further enhance their stability. It is found that increasing the hydrophobicity of the organosilane modified ATRP initiator reduces the susceptibility of the brushes toward cleavage. Robust, hydrophilic polymer brushes are prepared, which are obtained by introducing a short, hydrophobic PMMA or PEHMA block between the silicon oxide substrate and the hydrophilic polymer brush.

magnified image
A Strategy for Fabrication of Columnar Supramolecular Polymers by Highly Directional π‐π Stacking and Strong Multiple Ionic Bonds
Authors: Tao Kang , Bai Ruke , Zhao Xiulan , Wang Yanxue , Li Juan , Xue Lixin
Published: March 2011

A columnar supramolecular HDTP/HCTP polymer is prepared by simple addition of two oppositely charged triphenylene‐based monomers. 1H NMR indicates an ordered aggregate formation with parallel stacking of the aromatic subunits in aqueous solution. UV‐Vis and fluorescence spectra imply that HDTP and HCTP self‐assemble to construct H‐aggregates, in which two monomers have a strict geometric association with each other. A fiber‐like structure (and fiber aggregates) is also found in the solid state. The microstructure of the supramolecular polymer is also studied by WAXS. Based on the analyses, a tentative model for the columnar supramolecular polymer is proposed, which suggests the importance of directional π‐π interactions and strong multiple ionic bonds.

magnified image
Micromechanics of Soft Particles
Authors: Guo Mingyu , Wyss Hans M.
Published: March 2011

Materials that contain soft, deformable particles exhibit a rich range of macroscopic mechanical properties. Experimental access to the mechanics at the scale of a single particle is the basis for studying and understanding the macroscopic mechanics of these materials. In this paper, we discuss experimental methods that can be used to characterize the mechanics of microscopic soft particles. We focus on the recently developed capillary micromechanics method, which yields the full linear elastic behavior of a single particle. We validate the method by comparing results for the compressive modulus to osmotic compression measurements, which provide the most direct and unambiguous measure of compressibility. We find good agreement between the two methods on a system of deformable and compressible poly‐N‐isopropylacrylamide microgel particles. Our results thus support the validity of the capillary micromechanics method and suggest that it could be applied to a wide range of materials that consist of deformable soft objects.

magnified image
Natural Rubber Nanocomposites by In Situ Modification of Clay
Authors: Lowe David J. , Chapman Andrew V. , Cook Stuart , Busfield James J.C.
Published: March 2011

The fabrication of nanocomposites by organic modification of clay during mixing into NR is reported. NR/OMMT nanocomposites show more intercalation and exfoliation at higher modifier content, increasing the tensile modulus primarily by improved filler reinforcement. Comparison with nominally identical pre‐modified OMMT shows similar microstructures and physical properties. No effect of mixing duration is observed, indicating that modification is rapid. Unlike montmorillonite, unmodified sepiolite disperses well in NR, so organo‐modification improves compatibility but does not affect the nanocomposite microstructure. This means that organo‐sepiolite offers relatively small improvements over sepiolite as a filler for NR.

magnified image
Spherulite Growth Rate in Polypropylene/Silica Nanoparticle Composites: Effect of Particle Morphology and Compatibilizer
Authors: Palza H. , Vera J. , Wilhelm M. , Zapata P.
Published: March 2011

Spherical and tube‐like (TL) silica nanoparticles were melt blended with an isotactic polypropylene (PP) matrix and its effect on the isothermal spherulite growth rate was analyzed by polarized optical microscope. The addition of low amount (≈1 wt.‐%) of either 15 nm spherical or TL particles raises the spherulite growth rate and the nucleation density of spherulites. Samples prepared with silica spheres of 80 nm otherwise do not show any change in the crystallization behavior. By adding a compatibilizer, both the nucleation density and the spherulite growth rate of the pure polymer are increased. Noteworthy, although the nanoparticles do not further increase the nucleation density of the PP/compatibilizer blend, independent of its form and size, they cause a decrease in its spherulite growth rate.

magnified image
Electrogenerated Chemiluminescence of Pure Polymer Films and Polymer Blends
Authors: Chen Jiun‐Tai , Chang Ya‐Lan , Guo Song , Fabian Omar , Lackowski William M. , Barbara Paul F.
Published: March 2011

We recently reported the discovery of soliton‐like electrogenerated chemiluminescence (ECL) waves from pure conjugated polymer films and gold‐nanoparticles‐doped polymer films. In addition to a more detailed study of these polymer systems by changing the film thickness and the distribution of local leaks, we also apply the ECL wave phenomenon to polymer blends of conjugated and nonconjugated polymers. Poly(9,9‐dioctylfluorene‐co‐benzothiadiazole) (F8BT) is used as the active material that is oxidized and produces ECL with the presence of a co‐reactant, tri‐n‐propylamine (TPA). Several factors such as film thickness, artificial leaks, and solubility of doped polymers are examined for their effects on the ECL behavior. When polystyrene (PS), less soluble in the electrolyte, is blended with F8BT, dotted ECL signals are observed and transported as waves. When poly(methyl methacrylate) (PMMA), more soluble in the electrolyte, is blended with F8BT, PMMA serves as local scratches and ECL waves are triggered simultaneously from the whole film.

magnified image
Micro‐composite systems by in‐situ polymerizations
Authors: Ogata Naoya
Published: March 2011

In‐situ polycondensation of terephthaloyl chloride and p‐phenylenediamine was carried out by solution or interfacial polycondensation methods in the presence of rubbers such as styrene‐butadiene triblock copolymers and acrylonitrile‐butadiene random copolymers so that a novel composite polymer of rubbers and poly(p‐phenylenetere‐phthalamide) was obtained. Mechanical properties of rubbers were greatly improved by the incorporation of rigid rod‐like polymers.

In‐situ polymerization of N‐carboxy methyl‐L‐glutamate was carried out in solutions of rubbers so that a composite polymer of rubbers and poly(L‐glutamate) was obtained. Mechanical properties of rubbers were also greatly improved by the in‐situ polymerization, while solution blending of poly(L‐glutamate) did not result in the improvement of mechanical properties.
Perspectives in application of screw reactors in plastics processing
Authors: Uhland Eberhard , Wiedmann Werner
Published: March 2011

Twin‐screw reactors have proven to be a good technical and economical solution for the synthesis of polymers and their chemical modification. The main mechanical and process criteria for the chemical reaction process for this type of reactor are discussed. Examples for products economically produced already today and an outlook for other new processes under development are given.
Highly functional nucleid analogs
Authors: Takemoto Kiichi
Published: March 2011

Synthetic polymers having pendant nucleic acid bases were prepared by polymer design techniques. After thorough investigations on their chemical and physico–chemical properties, further studies on their applicability were done, and in particular, the analogs as photoresists, the analogs for high performance liquid chromatography, and the analogs applicable in the field of polymeric pharmaceuticals were shown.
Structural properties of partially charged poly (acrylic acid) gels as probed by light scattering
Authors: Candau Sauveur J. , Skouri Rachid , Schosseler François , Munch Jean‐Pierre
Published: March 2011

We report results of static light scattering for partially charged gels at different swelling degrees and different ionization degrees. We measured both the ensemble‐average and the rms fluctuations of the scattered intensity by scanning through various positions in the gel. It is shown that the dynamic concentration fluctuations are, to the first order, the same as in semi‐dilute solutions at the same concentration. The excess of scattering of the gel with respect to the solutions arises mainly from frozen‐in scattering domains with spatial extent less than ∼ 300 Å.
Structure of cellulose in cuoxam
Authors: Seger Bernd , Burchard Walther
Published: March 2011

Cuoxam ([CuII(NH3)4](OH)2) is a well known solvent for cellulose. Because of its deep blue colour, it has been used so far only for viscosity measurements. Direct light scattering measurements have not yet been reported in the literature.

We carried out static and dynamic light scattering measurements in cuoxam using the blue wavelength of λ0 = 457.9 nm from an Argon ion laser. The measurements were involved with some difficulties mainly caused by colloidal particles of CuO and Cu(OH)2 which could be removed by direct centrifugation of the cells. Furthermore, the scattering intensity had to be corrected for extinction. The refractive index increment was taken from the literature.

12 samples of different molecular weight and different origin were measured, and common power law behavior was found in a region up to about DPw = 1000 for both, the radius of gyration Rg and the hydrodynamic radius Rh, derived from the diffusion coefficient Dz. At higher degrees of polymerization characteristic deviations to lower radii occurred.These deviations are not caused by aggregation since the DPw's agreed with those from the cellulose tricarbanilates. The quantitative analysis of the radii and the angular dependence of the scattered light allowed determination of the chain stiffness. A Kuhn segment length of Ik = 25.6 (±6.2) nm and a characteristic ratio C∞ = 49.6 (±12.0) were derived. These values are close to those for cellulose‐tri‐carbanilate in dioxane.The reason for the increased stiffening is discussed on the basis of a special H‐bond model.
Alternating copolymerizations of 9,10–dicarbonyl–9,10–dihydroanthracene with 1,4–benzoquinones and 1,4–benzoquinone diimines: A novel preparative route to polyarylate and polyaramide
Authors: Iwatsuki Shouji , Itoh Takahito , Kozaki Masahiko
Published: March 2011

The anthracene–9, 10–bisketene compound 9, 10‐dicarbonyl‐9, 10–dihydroanthracene (1) was found to react spontaneously with a variety of benzoquinones and benzoquinone diimines to give aromatic polyesters and polyamides, respectively. These addition reactions are regarded as a novel preparative route to polyarylate and polyaramide.
Synthesis and properties of metal poly(butyl methacrylates) 7
Authors: Galo Cárdenas T. , Hernán Carbacho H. , Elizabeth Salgado C. , MarioRodriguez B.
Published: March 2011

Metal butyl methacrylate colloids were obtained by codeposition at 77K of the monomer with several metals such as Au, Pd, Cu, Ag, Zn, Cd, Ga, In, Ge, Sn, Sb and Bi. Au and Pd colloids are stable tor months at room temperature. The colloids were polymerized with different amounts of initiator benzoyl peroxide at 65°C for 25 min and a wide range of viscosity‐average molecular weights (103 <M̄v < 105) were obtained depending upon the metal used. The particle size of the clusters dispersed in the polymer matrix is around 500 A°. The polymers are stable even at 300°C, being Pd‐poly(butyl methacrylate) the most stable with 388.90°C. The metal content is ranging from 0.02 to 1.65 wt% for Sb and Pd, respectively. Polymers with different colors were obtained depending on the metal used.
Charge transport polymers for organic electroluminescent devices
Authors: Kido Junji , Hongawa Kenichi , Nagai Katsutoshi , Okuyama Katsuro
Published: March 2011

Triple‐layer‐type organic electroluminescent devices were fabricated using charge‐transporting poly(N‐vinylcarbazole) (PVK) as a hole‐transporting emitter layer. Electron‐transporting layers consisting of a triazole derivative (TAZ) and an aluminum complex (Alq) layer were used to maximize the carrier recombination efficiency. The EL device with a structure of glass substrate/indium‐tinoxide/PVK/TAZ/AIq/Mg:Ag showed bright blue emission from the PVK layer with a luminance of over 700 cd/m2. The emission color was tuned to a desirable color in the visible region through doping the PVK layer with fluorescent dyes. Bright white emission, in particular, was obtained for the first time at a high luminance level of over 3000 cd/m2 by using three kinds of fluorescent dyes each emitting red, green or blue.
Stereocomplex formation of isotactic poly(methyl methacrylate) with a wide variety of syndiotactic polymethacrylates
Authors: Hatada Koichi , Kitayama Tatsuki , Ute Koichi , Fujimoto Nobutaka , Miyatake Nobuo
Published: March 2011

Syndiotactic (st–) polymers of methacrylates with primary and secondary ester groups, prepared by the syndiotactic‐specific living polymerization with t‐C4H9Li/R3Al, were found to form stereocomplexes with isotactic (it–) poly(methyl methacrylate) (PMMA) by annealing in the solid state or by mixing in certain solvents such as acetone and toluene. Melting points of the complexes depend on the structure of the ester group and can be changed in a wide range of temperature. st–Polymers of tertiary esters did not form the complex. Effects of anneal conditions, molecular weight, and tacticity on the melting point of the complex were studied in some detail for the combination of st–poly(benzyl methacrylate) and it–PMMA. st–Random copolymers of MMA with several alkyl methacrylates also formed stereocomplexes with it–PMMA, whose melting point could be changed continuously by changing the composition in a certain range of temperature. st–Block copolymers of PMMA and poly(benzyl methacrylate) formed stereocomplexes with it–PMMA which showed two melting points, provided the block lengths are long enough for the two types of the com plexes to form independently. Stereoblock PMMA, it–PMMA–block–st–PMMA, and stereoblock copolymer, it–PMMA–block–st–poly(butyl methacrylate), were found to form stereocomplexes more easily than the corresponding mixtures. The stereoregular uniform PMMAs were used for elucidating the process of stereocomplex formation and its stoichiometry by means of gelpermeation chromatography (GPC). The preliminary results clearly indicated that the complexation occurs mainly in 1:1 stoichiometry in the beginning, while a small fraction of 1:2 (it–: st–) complex was also formed concomitantly. By similar GPC experiments using a series of uniform PMMAs, the minimum length of PMMA chains for the complex formation was found to be in the range of degrees of polymerization from 42 to 46.
Molecular design and synthesis of novel side‐chain liquid crystalline polymers
Authors: Kawakami Yusuke
Published: March 2011

Novel side‐chain liquid crystalline polymers were synthesized based on the molecular design of the chemical structures of main‐chain, spacer, and mesogenic groups. The main‐chain structures are polyether, by the cationic ring‐opening polymerization of oxetane derivatives, and polydiene, by the radical polymerization of diene derivatives. Some of the polymers from oxetanes with various mesogen and spacer groups show smectic liquid crystalline phase. Both cyano‐ and fluorine‐substituted biphenyls are good mesogenic groups in these liquid crystalline polymers. Polydiene also acts as a novel main‐chain to give smectic liquid crystalline state with cyanobiphenyl or fluorobiphenyl as a mesogen. Not only oligomethylene groups but also siloxane and oligo(oxyethylene) groups act as a component of the spacer groups to give liquid crystalline state.
Synthesis of membranes having a saccharide side chain and their optical resolution properties for d‐/l‐ glucose mixtures
Authors: Nakagawa Tsutomu , Toyokawa Yoshida , Abe Motoji , Higuchi Akon
Published: March 2011

The objective of the present investigation is to synthesize new polymeric membranes having a saccharide in the side chain and to clarify the specific affinity of the saccharide chains. During this study chloromethylated polysulfone (CM‐PSF), poly(chloromethylated styrene) (P‐CM‐St), poly(methyl methacrylate) (PMMA), and chlororethylated poly(γ ‐methyl L‐glutamate) (CE‐PMLG) as synthetic polymers along with an equal mixture of α‐D‐2‐deoxy‐2‐aminoglucopyranosyl‐(1'→6) ‐D‐sorbitol and mannitol (AGP) as saccharides were used. PMMA+AGP and CE‐PMLG+AGP membranes showed the highest permeability of D‐glucose in sugars (molecular weight = 180.16), although the CM‐PSP+AGP and P‐CM‐St+AGP membranes showed less permeability. The reason for the high permeability of D‐glucose is the high partition coefficient of D‐glucose, which may come from an interaction between the AGP terminating D‐glucose structure and D‐glucose as the solute. The optical resolution could be done by the difference between the D‐ and L‐glucose permeation rates from an equimolar mixture of D‐glucose and L‐glucose.
Proton transfer reactions in aqueous solution of 2‐vinylquinoline copolymers
Authors: Morales Elena , Gómez‐Antón M. Rosa , Piérola Inés F.
Published: March 2011

Fluorescence spectra of atactic and isolaclic poly‐2‐vinylquinoline and copolymers of 2‐vinylquinoline and four non fluorescent comonomers have been measured as a function of pH. The homopolymers and the copolymers with pyrrolidone show two band fluorescence spectra; their intensity ratio changes with pH, polymer concentration and excitation wavelength. For the other copolymers the emission of the protonated heterocycle is only a shoulder of the emission of the neutral form. A kinetic scheme has been proposed to explain these results.
Optical effects in stratified colloidal particles near transparency
Authors: Alexander‐Katz Roberto , De La Rosa Aída , Rojas Fernando , Contreras Claudia , Cardoso Judith
Published: March 2011

Non‐isotropic scattering patterns showing a minimum for small and almost transparent core‐shell particles are discussed. It is shown that for any particle size, close to transparency, a core‐shell particle behaves optically differently from a non‐structured particle due to the presence of a minimum in the scattering pattern. Transparency criteria are discussed in the light of the non‐isotropic character of the scattered light. Direct experimental evidence of the existence of this minimum is presented and compared with the theoretical predictions of the scattering by colloids having a distribution of particle composition.
Structure and thermodynamics of polystyrene‐block‐poly(ethylene/propene) micelles in selective solvents
Authors: Katime Issa , Villacampa Manuel , Quintana José R.
Published: March 2011

The concentration and temperature dependencies of micelle formation by a polystyrene‐block‐poly(ethylene/propene) copolymer in several ketones (2‐butanone, 3‐pentanone, 4‐methyl‐2‐pentanone, 4‐heptanone, 5‐methyl‐2‐hexanone and 5‐methyl‐3‐heptanone) were studied by static and dynamic light scattering, viscometry and size exclusion chromatography. No micelles were detected in solutions of 5‐methyl‐3‐heptanone. The standard Gibbs energy, ΔG°, the standard enthalpy, ΔH°, and the standard entropy, ΔS°, of micellization were estimated. The values of ΔG° and ΔH° were negative for all ketones studied and depended on the polar character of the ketone. The micelles showed larger association numbers and densities independent of the ketone. Micelle dimensions hardly depended on the ketone.
Blends of poly(n‐vinyl‐2‐pyrrolidone)/poly(monoitaconates) II. The coefficient of linear expansion
Authors: Opazo Alejandra , Gargallo Ligia , Radic Deodato
Published: March 2011

Blends of poly(monoitaconates)b) containing different side chain structures with poly(N‐vinyl‐2‐pyrrolidone) (PVP) of three different weight‐average molecular weights (M̄w) were studied by thermomechanical analysis. Blends containing PVP of M̄w =10000 shows a monotonous variation of the coefficient of linear expansion α against composition but PVP samples of higher molecular weights present a minimum which is attributed to polymer‐polymer complex due to strong specific interactions.
Binary polymer blends involving multiple specific interaction sites: Poly(vinyl methyl ether) blends with an ethyl methacrylate‐co‐4‐vinyl phenol copolymer
Authors: Xu Yun , Bhagwagar Dorab E. , Painter Paul C. , Coleman Michael M.
Published: March 2011

We report the results of experimental infrared and thermal analysis studies of binary miscible blends of poly(vinyl methyl ether) (PVME) with an ethyl methacrylate‐co‐4‐vinyl phenol (EMAVPh) copolymer. This is a complex blend system, involving multiple specific interaction sites. Using the concept of competing equilibria we show that the equilibrium constant describing hydrogen bonding between the OH group of EMAVPh and the ether oxygen of PVME can be determined from quantitative infrared spectroscopic analysis of the fraction of hydrogen bonded carbonyl groups present in miscible binary blends.
Synthesis, structure, and swelling behavior of two‐component copolymer networks
Authors: Shiomi Tomoo , Tezuka Yasuyuki , Okada Koji , Imai Kiyokazu , Hayashi Hisao
Published: March 2011

A two‐component copolymer network comprising polystyrene (PS) and poly(dimethylsiloxane) (PDMS) as copolymer components was prepared by cross‐linking PS with telechelic PDMS with a new method. The microphase structure of the dry PS/PDMS network was found to be irregular from DSC and small angle X‐ray scattering measurements. The swelling behavior was observed in three kinds of mixed solvents which were chosen so as to contrast with one another in respect of solubility of the component polymers. The observed swelling degree depended on the solvent composition in a manner peculiar to the respective mixed solvent systems. The Flory swelling equation extended to the two‐component polymer network qualitatively reproduced the experimental swelling behavior.
Kinetics of styrene uptake by a polyurethane network during the formation of interpenetrating polymer networks
Authors: Derrough Samir N. , Widmaier Jean‐Michel , Meyer Guy C.
Published: March 2011

Due to insolubility of the components, formation of interpenetrating polymer networks (IPNs) requires particular ways of synthesis. Among others, IPNs can be prepared by the sequential technique where a network is swollen in a monomer and its crosslinker, which are then polymerized in situ. The simplest case is to swell at equilibrium; however this leads to IPNs of a given composition. For obtaining other compositions, swelling has to be stopped before equilibrium, or the swollen network (gel) has to be deswollen to a certain extent. Therefore, diffusivity of the monomer within the gel has to be known. The kinetics of monomer uptake was studied for a polyether urethane/styrene‐divinylbenzene system which gives transparent materials despite the difference in refractive indexes. This allows direct visual observations of the monomer progress within the network. The results are not fully in agreement with the theories of Tanaka and of Candau which both predict the progression of a solvent in a polymeric gel. Two regimes of swelling depending on the concentration distribution of the monomer within the gel were found.
Dynamics of cyclic poly(methylphenylsiloxane)
Authors: Maçanita Antonio L. , Horta Arturo , Piérola Inés F.
Published: March 2011

Fluorescence spectra of cyclic poly(methylphenylsiloxane)s having 3, 4.4 and 9.0 monomelic units, and of the monochromophoric analog methylphenyldimethoxysilane (MS), were measured as a function of temperature in the range 150 to 320 K. Both the low‐ and the high‐temperature limits were reached in this range. The crossover temperature between both limits was thus determined, as well as the activation energy for excimer formation and the excimer binding enthalpy. From measurements of the lifetime of MS as a function of temperature, the rate constant for excimer formation was also determined, and its relationship with the rate constant for rotation through backbone bonds was discussed.
Developments in the cationic polymerization of alkenes — A personal view
Authors: Plesch Peter H.
Published: March 2011

In this paper the author presents some of his contributions to the theory and practice of the cationic polymerization (C.P.) of alkenes since 1944. The first phase of his work at the University of Manchester comprises the discovery of co‐catalysis by water with TiCl4, the invention of the pseudo‐Dewar reaction vessel, the use of trichloroacetic acid as co‐catalyst, and the disproof of the alleged cationic isomerization of cis‐stilbene.