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See detailReactive compatibilization of PC/PVDF polymer blends by zinc carboxylate containing poly(methylmethacrylate)ionomers
Moussaif, Noureddine; Pagnoulle, Christophe; Jérôme, Robert ULg

in Polymer (2000), 41(15), 5551-5562

Polycarbonate (PC) has been reacted with a random copolymer of methylmethacrylate and 6 mol% of acrylic acid (poly(MMA-co-AA)) and with this copolymer neutralized (totally or not) by Zn cations. When ... [more ▼]

Polycarbonate (PC) has been reacted with a random copolymer of methylmethacrylate and 6 mol% of acrylic acid (poly(MMA-co-AA)) and with this copolymer neutralized (totally or not) by Zn cations. When conducted in solution at 240°C, the reaction leads to the grafting of PC onto the copolymer neutralized or not. In the melt at 235°C, the grafting reaction occurs only when the copolymer is at least partly neutralized. Whatever the experimental conditions (solution or bulk), PMMA does not react with PC, which confirms that the acidolysis of PC is at the origin of the grafting reaction. Poly(vinylidene fluoride) (PVDF) and PC have been melt blended at 235°C in the presence of the poly(MMA-co-AA) copolymer totally neutralized or not by Zn cations, the purpose being the reactive formation of PMMA-g-PC copolymer that would act as compatibilizer for the PC/PVDF blend. The phase morphology and the mechanical properties of the compatibilized PC/PVDF blends have been compared with the parent non-reactive polyblends. Compared to the modification of PVDF by 20 wt% of PMMA, the use of 20 wt% of the partly neutralized poly(MMA-co-AA) copolymer decreases further the average size of the dispersed phase, enhances its adhesion to the matrix, and results in a considerable increase of the elongation at break. The beneficial effect of zinc carboxylate in the PMMA copolymer is explained by the grafting of PC onto PMMA at the interface. [less ▲]

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See detailReactive compatibilization of SAN/EPR blends. 1. Dependence of the phase morphology development on the reaction kinetics
Pagnoulle, Christophe; Koning, Cor; Leemans, Luc et al

in Macromolecules (2000), 33(17), 6275-6283

SAN containing 20 wt % of reactive SAN-X has been melt blended with EPDM containing 50 wt % of EP chains grafted by maleic anhydride (EP-g-MA). Two types of reactive groups (X) have been attached to SAN ... [more ▼]

SAN containing 20 wt % of reactive SAN-X has been melt blended with EPDM containing 50 wt % of EP chains grafted by maleic anhydride (EP-g-MA). Two types of reactive groups (X) have been attached to SAN (2 mol % of X), i.e., a primary amine and a precursor of it at the processing temperature, i.e., a carbamate. The SAN/rubber weight composition was kept constant at 75/25. The development of the phase morphology from pellet-sized rubber particles to dispersed submicrometer droplets has been investigated during reactive mixing for the two types of reactive SAN and has been found to depend on the interpolymer reaction rate and thus on the relative reactivity of the amine and the carbamate groups attached to SAN toward the maleic anhydride function of EP. [less ▲]

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See detailReactive compatibilization of SAN/EPR blends. 2. Effect of type and content of reactive groups randomly attached to SAN
Pagnoulle, Christophe; Jérôme, Robert ULg

in Macromolecules (2001), 34(4), 965-975

Kinetics of the poly(styrene-co-acrylonitrile)/poly(ethylene-co-propylene) (SAN/EPR) interfacial reaction has been varied by changing both the average number of reactive groups per SAN chain and the ... [more ▼]

Kinetics of the poly(styrene-co-acrylonitrile)/poly(ethylene-co-propylene) (SAN/EPR) interfacial reaction has been varied by changing both the average number of reactive groups per SAN chain and the content of reactive SAN in the SAN phase, while keeping constant the overall SAN/EPR composition, i.e., 75/25 w/w. For this purpose, reactive SAN chains containing 0.004, 0.028, 0.049, and 0.078 mol/wt % of either primary amine or carbamate (an amine precursor) have been synthesized, and the content of reactive SAN in the SAN phase has been changed from 2.5 to 73.33 wt %. It appears that the number and type of reactive groups attached onto SAN affect not only the extent of the compatibilization reaction but also the compatibilization capability of the in situ formed graft copolymer in a strong dependence on molecular weight and molecular architecture. [less ▲]

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See detailReactive compatibilization of SAN/EPR blends: Effect of kinetics of the compatibilization reaction on the interfacial adhesion
Pagnoulle, Christophe; Jérôme, Robert ULg

in Macromolecular Symposia (2000), 149

The very poor adhesion between films of styrene and acrylonitrile random copolymer (SAN) and maleic anhydride grafted polypropylene (PP-g-MA) can be dramatically improved by an intermediate thin layer of ... [more ▼]

The very poor adhesion between films of styrene and acrylonitrile random copolymer (SAN) and maleic anhydride grafted polypropylene (PP-g-MA) can be dramatically improved by an intermediate thin layer of SAN bearing groups reactive toward maleic anhydride. The rate of the interfacial reaction, which is controlled by the reactive groups attached to SAN (amine vs. carbamate) and by the method used to build up the sandwich assembly, has a decisive effect on the capability of the SAN-g-PP graft copolymer formed at the interface to improve the fracture toughness in direct dependence on its molecular architecture. [less ▲]

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See detailReactive compatibilization of SAN/EPR blends: Effect of rubber content and reactivity of the SAN functional groups
Pagnoulle, Christophe; Martin, Philippe; Jérôme, Robert ULg

in Macromolecular Chemistry and Physics (2000), 201(16), 2181-2194

SAN containing 20 wt.-% reactive SAN-X was melt blended with EPDM containing 50 wt.-% maleic anhydride EPR grafted chains (EP-g-MA). The rubber content was changed from 15 to 80 wt.-%, and 2 types of ... [more ▼]

SAN containing 20 wt.-% reactive SAN-X was melt blended with EPDM containing 50 wt.-% maleic anhydride EPR grafted chains (EP-g-MA). The rubber content was changed from 15 to 80 wt.-%, and 2 types of reactive groups (X) were attached to SAN (0.028 mol X/ wt.-%), i. e. primary amines and carbamates which are primary amine precursors at the processing temperature. Phase morphology, tensile properties and impact strength depend not only on the rubber content but also on the relative reactivity of the amine and the carbamate groups towards maleic anhydride, in a strong dependence on the reaction rate and the reaction completeness. The dispersion mechanism has been discussed, including formation of sub-inclusions. Dependence of the impact resistance on the rubber phase content for non-reactive blends (□) and blends modified by SAN-NH2 (;) and SAN-carb (o), respectively. [less ▲]

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See detailReactive Oxygen Intermediate-Dependent Nf-Kappab Activation by Interleukin-1beta Requires 5-Lipoxygenase or Nadph Oxidase Activity
Bonizzi, Giuseppina; Piette, Jacques ULg; Haterte, Stéphanie ULg et al

in Molecular & Cellular Biology (1999), 19(3), 1950-60

We previously reported that the role of reactive oxygen intermediates (ROIs) in NF-kappaB activation by proinflammatory cytokines was cell specific. However, the sources for ROIs in various cell types are ... [more ▼]

We previously reported that the role of reactive oxygen intermediates (ROIs) in NF-kappaB activation by proinflammatory cytokines was cell specific. However, the sources for ROIs in various cell types are yet to be determined and might include 5-lipoxygenase (5-LOX) and NADPH oxidase. 5-LOX and 5-LOX activating protein (FLAP) are coexpressed in lymphoid cells but not in monocytic or epithelial cells. Stimulation of lymphoid cells with interleukin-1beta (IL-1beta) led to ROI production and NF-kappaB activation, which could both be blocked by antioxidants or FLAP inhibitors, confirming that 5-LOX was the source of ROIs and was required for NF-kappaB activation in these cells. IL-1beta stimulation of epithelial cells did not generate any ROIs and NF-kappaB induction was not influenced by 5-LOX inhibitors. However, reintroduction of a functional 5-LOX system in these cells allowed ROI production and 5-LOX-dependent NF-kappaB activation. In monocytic cells, IL-1beta treatment led to a production of ROIs which is independent of the 5-LOX enzyme but requires the NADPH oxidase activity. This pathway involves the Rac1 and Cdc42 GTPases, two enzymes which are not required for NF-kappaB activation by IL-1beta in epithelial cells. In conclusion, three different cell-specific pathways lead to NF-kappaB activation by IL-1beta: a pathway dependent on ROI production by 5-LOX in lymphoid cells, an ROI- and 5-LOX-independent pathway in epithelial cells, and a pathway requiring ROI production by NADPH oxidase in monocytic cells. [less ▲]

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See detailReactive oxygen species downregulate the expression of pro-inflammatory genes by human chondrocytes.
Mathy, Marianne ULg; Martin, G.; Devel, P. et al

in Inflammation Research (2003), 52(3), 111-8

OBJECTIVES: To determine the regulatory effects of reactive oxygen species (ROS) on the expression by human osteoarthritic chondrocytes of interleukin (IL)-1beta, -6 and -8, inducible nitric oxide ... [more ▼]

OBJECTIVES: To determine the regulatory effects of reactive oxygen species (ROS) on the expression by human osteoarthritic chondrocytes of interleukin (IL)-1beta, -6 and -8, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) gene in response to interleukin (IL)-1beta or lipopolysaccharide (LPS). METHODS: Human chondrocytes in monolayer culture were incubated for 3 h with ROS generating molecules such as S-nitroso-N-acetyl-D,L-penicillamine (SNAP, 100 microM), 3-morpholinosydnonimine (SIN-1, 100 microM), with chemically synthesised peroxynitrite (ONOO-, 10 microM) or hydrogen peroxide (H2O2, 100 microM). After treatment by ROS, chondrocytes were washed and then cultured for the next 24 h with or without lipopolysaccharide LPS (10 microg/ml) or IL-1beta (1.10(-11) M). IL-1beta, IL-6, IL-8, iNOS and COX-2 gene expression was analysed by real time and quantitative RT PCR. IL-6, IL-8 and prostaglandin (PG) E2 productions were assayed by specific immunoassays. Nitrite was measured in the culture supernatants by the Griess procedure. RESULTS: LPS and IL-1beta stimulated IL-1beta, IL-6, IL-8, iNOS and COX-2 gene expression. SNAP significantly downregulated LPS induced overall gene expressions, whereas SIN-1 had no effect. ONOO- inhibited iNOS and COX-2 gene expression but not that of the cytokine genes. When chondrocytes were incubated with IL-1beta, SIN-1 and ONOO dramatically decreased all gene expressions while SNAP was inefficient. H2O2 treatment inhibited both LPS and IL-1beta induced gene expressions. CONCLUSIONS: These data provide an evidence that ROS may have anti-inflammatory properties by depressing inflammatory gene expression. Further, we demonstrate that ROS effects are dependent on the nature of radical species and the signalling pathway that is activated. These findings should be taken into consideration for the management of antioxidant therapy in treatment of inflammatory joint diseases. [less ▲]

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See detailReactive oxygen species downregulate the expression of pro-inflammatry genes by humachondrocytes
Henrotin, Yves ULg; Mathy-Hartert, Marianne ULg; Martin, G. et al

in Osteoporosis International (2002, November), 13(Suppl. 3), 53

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See detailReactive transport modelling of a groundwater contamination by ammoniacal liquor
Haerens, Bruno; Prommer, Henning; Lerner, David N. et al

(2006)

A reactive transport modeling study was carried out to assess the fate of a groundwater contamination by ammoniacal liquor from a former coking plant and the associated geochemical response. The ... [more ▼]

A reactive transport modeling study was carried out to assess the fate of a groundwater contamination by ammoniacal liquor from a former coking plant and the associated geochemical response. The simulations over a 45-year period provide a conclusive explanation and quantitative description of all measured data from observation wells down gradient of the contaminant source. It is shown that cation exchange exerts the main control on the fate of the ammonium plume as it strongly retards the migration of dissolved ammonium. The sorption of ammonium is accompanied by the elution of native cations, an effect that can be seen in some observation wells where ammonium is absent. While phenol has not been detected in the observation wells in recent years, the modeling results suggest that it has completely degraded in the aquifer, which is inferred from the agreement between the simulated and the observed geochemical fingerprint that the degradation of phenol imposes on groundwater composition. [less ▲]

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See detailReactive transport modelling of Ammonium: 1D Conceptual modelling and comparison of reactive transport codes
Haerens, Bruno; Dassargues, Alain ULg; Lerner, David

in Acta Universitatis Carolinae. Geologica (2002), 46(2-3), 27-31

Contamination of NH4+, as main inorganic contaminant, resulted from disposal of ammoniacal liquor at a former coal carbonisation plant at Mansfield, UK. Previous research for evaluating natural ... [more ▼]

Contamination of NH4+, as main inorganic contaminant, resulted from disposal of ammoniacal liquor at a former coal carbonisation plant at Mansfield, UK. Previous research for evaluating natural attenuation (Davison, 1998; Davison and Lerner, 2000; Jones, 2001; Jones et al., 1998; Jones and Lerner, 2001) revealed strong retardation of NH4+ in the aquifer due to cation exchange with existing cations on the sediment. After disposal of ammoniacal liquor, NH4+ entered the aquifer and equilibrium took place between NH4+, the existing cations and the available exchange sites. An existing hydraulic gradient keeps flushing the contaminated aquifer with pristine background water. NH4+ desorbs progressively due to new cation exchange equilibrium when the input of NH4+ decreases or eventually stops. In order to be able to model the reactive transport of NH4+, a reaction module is set up for future 2D/3D reactive transport modelling of NH4+ using PHT3D. In a first approach a conceptual 1D-model example is considered and two multicomponent reactive transport models, PHT3D (Prommer and Barry, 2001; Prommer et al., 1999) and PHREEQC (Parkhurst and Appelo, 1999), are compared. In the 1D-model example, the flushing of ammonium contaminated groundwater by pristine background water is simulated. The included processes are advection, dispersion and cation exchange between NH4+, Ca2+, Mg2+, K+, Na+ and the sediment. As both models are using the same geochemical module, the comparison focuses on the coupling approach between the transport and geochemical modules. Results show that large numbers of pore volumes (i.e., a nondimensional time parameter where elapsed time is divided by the hydrodynamic residence time (Brusseau, 1994)) are needed to flush the NH4+ off the aquifer sediment. From the comparison of simulation results compiled with the two codes it is clear that an appropriate choice of the reaction step size for the sequential coupling between the transport and geochemistry modules, is a major point for accuracy of the model predictions. [less ▲]

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See detailReactively and physically compatibilized immiscible polymer blends: Stability of the copolymer at the interface
Harrats, Charef; Dedecker, Kristof; Groeninckx, Gabriel et al

in Macromolecular Symposia (2003), 198

This paper reports on the interfacial behaviour' of block and graft copolymers used as compatibilizers in immiscible polymer blends. A limited residence time of the copolymer at the interface has been ... [more ▼]

This paper reports on the interfacial behaviour' of block and graft copolymers used as compatibilizers in immiscible polymer blends. A limited residence time of the copolymer at the interface has been shown in both reactive blending and blend compatibilization by preformed copolymers. Polystyrene (PS)/polyamide6 (PA6), polyphenylene oxide (PPO)/ PA6 and polymethylmethaciylate (PMMA)/PA6 blends have . been reactively compatibilized by a styrene-maleic anhydride copolymer SMA. The extent of miscibility of SMA with PS, PPO and PMMA is a key criterion for the stability of the graft copolymer' at the interface. For the first 10 to 15 minutes of mixing, the in situ formed copolymer is able to decrease the particle size of the dispersed phase and to prevent it from coalescencing. However, upon increasing mixing time, the copolymer leaves the interface which results in phase coalescence. In PS/LDPE blends compatibilized by preformed PS / hydrogenated polybutadiene (hPB) block copolymers, a tapered diblock stabilizes efficiently a co-continuous two-phase morphology, in contrast to a triblock copolymer that was unable to prevent phase coarsening during annealing at 180°C for 150 minutes. [less ▲]

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See detailReactivite bronchique chez les patients diabetiques.
Piéron, Maurice ULg; Scheen, André ULg; Corhay, Jean-Louis ULg et al

in Revue des Maladies Respiratoires (1997), 14(5), 379-85

The data of the literature concerning bronchial reactivity in diabetic patients are controversial. Therefore, we studied the influence of the presence of a diabetic cardiac autonomic neuropathy (CAN) on ... [more ▼]

The data of the literature concerning bronchial reactivity in diabetic patients are controversial. Therefore, we studied the influence of the presence of a diabetic cardiac autonomic neuropathy (CAN) on the ventilatory parameters measured during a methacholine-induced bronchoconstriction test. Ten insulin-dependent diabetic patients without CAN, ten insulin-dependent diabetic patients with CAN and ten healthy volunteers, all non-smokers and free of respiratory symptoms, have undergone a functional respiratory check-up before the methacholine test. The presence of CAN was classically studied by the decrease in heart rate changes during three standardized tests (deep breathing at 6 cycles/min, Valsalva manoeuver, orthostatism) which all mainly explore the parasympathetic function. The bronchial response to methacholine was similar in the healthy subjects and in the diabetic patients without CAN. However, the fall in forced expiratory volume in 1 second induced by the highest dose of methacholine was significantly less marked in the diabetic subjects with CAN than in the two other groups. These results suggest that the diabetic autonomic neuropathy also involves the vagal innervation of the respiratory tract. [less ▲]

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See detailRéactivité du tétroxyde d'osmium et des osmates vis-à-vis des séléniures et des sélénoxydes: application à la synthèse d'alcools allyliques et à la dihydroxylation énantiosélective d'oléfines
Colaux, Catherine ULg

Doctoral thesis (2002)

Ce travail traite de l’équilibre réactionnel établi entre le tétroxyde d’osmium et les séléniures d’une part et les osmates (VI) et les sélénoxydes d’autre part. La thèse se divise en trois grandes ... [more ▼]

Ce travail traite de l’équilibre réactionnel établi entre le tétroxyde d’osmium et les séléniures d’une part et les osmates (VI) et les sélénoxydes d’autre part. La thèse se divise en trois grandes parties : 1. L’oxydation des allylséléniures par l’AD-mix 2. L’utilisation des sélénoxydes comme oxydants des sels osmiques (VI) 3. L’établissement de l’existence de l’équilibre réactionnel précité La réaction d’oxydation des allylséléniures par l’AD-mix nous a permis de décrire une réaction dont la chemosélectivité dépend largement de la nature du groupement sélénié mais également de la nature et du degré de substitution de la double liaison. Nous avons au cours de ce travail comparé la réactivité d’une double liaison carbone-carbone comportant une espèce séléniée en position allylique avec celle de son homologue alkylé. Enfin, nous avons dans deux cas déterminé la stéréochimie absolue et relative des diols séléniés générés par oxydation des doubles liaisons carbone-carbone. L’utilisation des sélénoxydes comme co-oxydants des sels osmiques (VI) a conduit à un nouveau système de dihydroxylation catalytique énantiosélective d’oléfines générant dans tous les cas les diols correspondants avec de bons rendements chimiques et d’excellents excès énantiomériques. Une étude de l’influence exercée par la nature du sélénoxyde sur la réaction nous a permis d’une part de sélectionner le sélénoxyde le plus adapté à notre système mais également de déterminer l’étape limitante de vitesse. Enfin, nous avons posé les bases d’un système de dihydroxylation catalytique énantiosélective impliquant la génération in situ des sélénoxydes par oxydation du séléniure présent en quantité catalytique avec l’oxygène singulet généré photochimiquement. Enfin, nous avons démontré l’existence de l’équilibre reliant les quatre espèces (osmium (VIII), séléniure et osmate (VI), sélénoxyde). Cet équilibre a été mis à profit pour générer sélectivement des alcool allyliques. Dissertation doctorale en Sciences Chimiques Le 28 Janvier 2002 Laboratoire de Chimie Organique de Synthèse Promoteur : Prof. A. Krief [less ▲]

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See detailReactivity and Collisionally Activated Dichlorocarbene Dications studied by Tandem Mass Spectrometry.
Leyh, Bernard ULg; Hautot, D.

in Journal of the American Society for Mass Spectrometry (1995), 6

The dissociation mechanisms of dichlorocarbene dications following collisional activation have been investigated via tandem mass spectrometric technique and semi-empirical calculations. Three channels ... [more ▼]

The dissociation mechanisms of dichlorocarbene dications following collisional activation have been investigated via tandem mass spectrometric technique and semi-empirical calculations. Three channels appear to be significant: (CCl2)2+->CCl+(X1Sigma+)+Cl+(3P) (channel 1); (CCl2)2+->CCl+(X1Sigma+)+Cl+(1D) (channel 2); (CCl2)2+->(Cl2)+(X2Pig)+C+(2P). The second channel becomes dominant at high internal energy. Production of ground state fragments (channel 1) involves a transition driven by spin-orbit coupling from the (CCl2)2+ X 1Sigma+g state to the (CCl2)2+ a 3Sigma-u state en route to the fragments. The dissociation barrier for the production of the ground state fragments from the ground electronic state of (CCl2)2+ via the spin-orbit-induced transition is equal to 420 kJ/mol. The dissociation pathway that corresponds to channel 3 includes a first isomerization step from the linear (Cl-C-Cl)2+ structure to a bent (Cl-C-Cl)2+ connectivity. The calculated isomerization barrier amounts to 550 kJ/mol. The calculated reverse activation barriers are compatible with the measured kinetic energy released on the fragments. [less ▲]

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See detailReactivity of (R)-4-phenyloxazolidin-2-thione chiral auxiliary: from deprotection to heterocyclic interconversion
Monbaliu, Jean-Christophe ULg; Tinant, Bernard; Marchand-Brynaert, Jacqueline

in Heterocycles (2008), 75

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See detailReactivity of auranofin with selenols and thiols: implications for the anticancer activity of gold(I) compounds
Di Sarra, Francesca; Fresch, Barbara ULg; Bini, Riccardo et al

in European Journal of Inorganic Chemistry [=EurJIC] (2013), 2013(15), 2718

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See detailReactivity of autoantibodies in systemic lupus erythematosus with synthetic core histone peptides.
Muller, S.; Bonnier, D.; Thiry, Marc ULg et al

in International Archives of Allergy and Applied Immunology (1989), 89(2-3), 288-96

The specificity of autoantibodies present in the serum of 151 patients with systemic lupus erythematosus (SLE) was investigated by ELISA using as antigen individual histones as well as 17 different core ... [more ▼]

The specificity of autoantibodies present in the serum of 151 patients with systemic lupus erythematosus (SLE) was investigated by ELISA using as antigen individual histones as well as 17 different core histone synthetic peptides. Many of the sera reacted with four terminal peptides (residues 1-21 and 130-135 of H3, 1-29 of H4 and 1-25 of H2B) while fewer reacted with internal peptides (residues 65-85 of H2A and 40-55 of H3). Of the 151 SLE sera, 88% reacted with one or more of the six core histone peptides whereas only 57% reacted with one or more of the complete core histone molecules. Antibodies to mononucleosomes from chicken erythrocytes were also prepared in rabbits. The rabbit antisera were tested by ELISA using as antigen chromatin subunits, native and denatured DNA, individual histones and 23 natural and synthetic peptides of histones. The antinucleosome antibodies were found to recognize the same peptide fragments as those recognized by the SLE sera. [less ▲]

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See detailReactivity of functional SAN toward coreactive EPR-g-MA at planar interface
Pagnoulle, Christophe; Moussaif, Noureddine; Riga, Joseph et al

in Journal of Polymer Science. Part A, Polymer Chemistry (2000), 38(19), 3682-3689

The grafting kinetics of reactive poly(styrene-co-acrylonitrile) (SAN) onto EPR-g-MA was studied under isothermal conditions, at the planar interface of an SAN/ethylene-propylene rubber (EPR) bilayer film ... [more ▼]

The grafting kinetics of reactive poly(styrene-co-acrylonitrile) (SAN) onto EPR-g-MA was studied under isothermal conditions, at the planar interface of an SAN/ethylene-propylene rubber (EPR) bilayer film in relation to the type of reactive groups, NH2 versus carbamate (which is an amine precursor), attached to SAN. The amount of SAN chemically bound to EPR chains at the interface was estimated by selectively washing off the unreacted SAN chains before X-ray photon spectroscopic analysis of the released surface. It is clear that the mutual reactivity of the reactive groups, i.e., the NH2-MA pair versus the carbamate-MA pair, has a decisive effect on the amount of SAN that reacts with EPR-g-MA at the interface. In case of SAN-carb, the grafting reaction is controlled by the thermolysis of the carbamate groups into primary amines. [less ▲]

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