Specific interaction between polyethylenimine and azo dyes carrying hydroxyl groups

1985 ◽  
Vol 23 (1) ◽  
pp. 37-47 ◽  
Author(s):  
Toru Takagishi ◽  
Kiyoaki Yoshikawa ◽  
Hiromitsu Hamano ◽  
Nobuhiko Kuroki ◽  
Hiroshi Kozuka
Keyword(s):  
Azo Dyes ◽  
Specific Interaction ◽  
Hydroxyl Groups

Effects of metal ions on the interaction between polyethylenimine and azo dyes carrying hydroxyl groups

1985 ◽  
Vol 23 (1) ◽  
pp. 255-259 ◽  
Author(s):  
Toru Takagishi ◽  
Kiyoaki Yoshikawa ◽  
Sadatsugu Okuda ◽  
Nobuhiko Kuroki ◽  
Hiroshi Kozuka
Keyword(s):  
Metal Ions ◽  
Azo Dyes ◽  
Hydroxyl Groups

Reinforcement of Silicone Rubber by Particulate Silica

1975 ◽  
Vol 48 (4) ◽  
pp. 558-576 ◽  
Author(s):  
B. B. Boonstra ◽  
H. Cochrane ◽  
E. M. Dánnenberg
Keyword(s):  
Silicone Rubber ◽  
Silica Surface ◽  
Specific Interaction ◽  
Interaction Coefficient ◽  
Hydroxyl Groups ◽  
Surface Hydroxyl ◽  
Silanol Groups ◽  
Compression Set ◽  
Surface Hydroxyl Groups ◽  
Bound Rubber

Abstract The interaction between fumed silica and silicone elastomer after various treatments of the silica surface has been investigated. The effect of the treatments was determined by measuring bound rubber, an interaction coefficient by means of the oscillating disk rheometer, the mechanical properties of the vulcanizates, the morphology of the silica aggregates, and the use of an hydroxyl-terminated silicone rubber. The results indicated that the interaction is much more intensive than in carbon black-hydrocarbon rubber systems. This is demonstrated by much higher bound rubber values (by a factor of 2–3) and a higher interaction coefficient. It is shown that the major effect on this interaction coefficient is the specific interaction by hydrogen bonding, between silica surface silanol groups and the polydimethylsiloxane chain. In this bonding the isolated hydroxyl groups should play the major part. Partial inactivation of these isolated silanol groups leads to improved strength but lower modulus. Maximum inactivation of the surface hydroxyl groups leads to soft compounds with lower tensile strengths and moduli, as well as very low bound rubber. Replacement of surface hydroxyl groups by vinyldimethylsilyl groups did not have the expected activating effect. Apparently the attached vinyldimethylsilyl groups do not form crosslinks with the elastomer chains, so that the overall result of the presence of these groups on the silica surface is a weakening of the interaction with the silicone rubber chains, although to a lesser degree than in the case of trimethylsilyl groups. The interaction between filler surface and polysiloxane can be maximizedby the use of a hydroxyl-terminated elastomer. The terminal groups will react with the silica surface so strongly that the particles act as crosslinks after proper heat treatment and a crosslinked polymer is obtained with a tensile strength of the same level as a peroxide-crosslinked vulcanizate but with higher compression set. At the temperature of the compression set test (175°C) the bonds apparently rearrange so that the permanent deformation is practically 100%. Quantitative data have been presented which prove that breakdown of silica aggregates does occur during mixing in silicone rubber on a two-roll mill.

scholarly journals Membrane Interactivity of Anesthetic Adjuvant Dexmedetomidine Discriminable from Clonidine and Enantiomeric Levomedetomidine

2019 ◽  
pp. 1-15
Author(s):  
Maki Mizogami ◽  
Hironori Tsuchiya
Keyword(s):  
Membrane Fluidity ◽  
Lipid Rafts ◽  
Lipid Bilayers ◽  
Nerve Cell ◽  
Adrenergic Receptors ◽  
Membrane Lipids ◽  
Specific Interaction ◽  
Hydroxyl Groups ◽  
Clinical Effects ◽  
Adrenergic Agonists

Aims: Dexmedetomidine, which has been increasingly used as an anesthetic adjuvant, is more lipophilic and more active than another α2-adrenergic agonist clonidine and enantiomeric levomedetomidine. Lipophilicity and stereostructure affect the clinical effects of α2-adrenergic agonists. We aimed to compare the membrane interactivity of dexmedetomidine with clonidine and levomedetomidine from a point of view different from the mode of action on α2-adrenergic receptors. Methodology: Unilamellar vesicles were prepared with phospholipids and cholesterol to mimic the lipid compositions of peripheral nerve cell, central nerve cell and cardiomyocyte membranes, and lipid rafts. They were subjected to the reactions with dexmedetomidine, clonidine and levomedetomidine at 10-200 μM, followed by measuring fluorescence polarization to determine the membrane interactivity to change membrane fluidity and specify the membrane region for the stereostructure-specific interaction. Results: Dexmedetomidine and clonidine acted on lipid bilayers to increase the membrane fluidity with potencies varying by a compositional difference of membrane lipids. Dexmedetomidine showed greater interactivity with neuro-mimetic and cardiomyocyte-mimetic membranes than clonidine, being consistent with their comparative lipophilicity and activity. The effects of α2-adrenergic agonists on lipid raft model membranes were much weaker than those on other membranes, indicating that lipid rafts are not mechanistically relevant to them. Higher interactive dexmedetomidine was discriminated from lower interactive levomedetomidine in the presence of chiral cholesterol in membranes. An interactivity difference between two enantiomers was largest in the superficial region of lipid bilayers and the rank order of their membrane-interacting potency was reversed by replacing cholesterol with epicholesterol, suggesting that cholesterol’s 3β-hydroxyl groups positioned close to the membrane surface are responsible for the enantioselective interaction. Conclusion: Dexmedetomidine structure-specifically interacts with biomimetic membranes depending on their lipid compositions more potently than clonidine and levomedetomidine. Such membrane interactivity associated with higher lipophilicity and stereostructure characterizes dexmedetomidine in addition to higher affinity for α2-adrenergic receptors.

scholarly journals Degradation of Azo Dyes with Different Functional Groups in Simulated Wastewater by Electrocoagulation

Water ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 123
Author(s):  
Yang Liu ◽  
Chenglong Li ◽  
Jia Bao ◽  
Xin Wang ◽  
Wenjing Yu ◽  
...  
Keyword(s):  
Functional Groups ◽  
Azo Dyes ◽  
Current Intensity ◽  
Hydroxyl Groups ◽  
Time Saving ◽  
Alizarin Yellow ◽  
Energy Conserving ◽  
Carcinogenic Effects ◽  
Simulated Wastewater ◽  
Hydroxyl Free Radicals

Increasing attention has been paid to the widespread contamination of azo dyes in water bodies globally. These chemicals can present high toxicity, possibly causing severe irritation of the respiratory tract and even carcinogenic effects. The present study focuses on the periodically reverse electrocoagulation (PREC) treatment of two typical azo dyes with different functional groups, involving methyl orange (MO) and alizarin yellow (AY), using Fe-Fe electrodes. Based upon the comparative analysis of three main parameters, including current intensity, pH, and electrolyte, the optimal color removal rates for MO and AY could be achieved at a rate of up to 98.7% and 98.6%, respectively, when the current intensity is set to 0.6 A, the pH is set at 6.0, and the electrolyte is selected as NaCl. An accurate predicted method of response surface methodology (RSM) was established to optimize the PREC process involving the three parameters above. The reaction time was the main influence for both azo dyes, while the condition of PREC treatment for AY simulated wastewater was time-saving and energy conserving. According to the further UV–Vis spectrophotometry analysis throughout the procedure of the PREC process, the removal efficiency for AY was better than that of MO, potentially because hydroxyl groups might donate electrons to iron flocs or electrolyze out hydroxyl free radicals. The present study revealed that the functional groups might pose a vital influence on the removal efficiencies of the PREC treatment for those two azo dyes.

Interactions entre les cations et les sucres. I. Évaluation de l'enthalpie libre d'interaction Ca2+ − D-(−)-ribose dans l'eau à 25 °C

1985 ◽  
Vol 63 (10) ◽  
pp. 2639-2643 ◽  
Author(s):  
Jean-Pierre Morel ◽  
Claude Lhermet
Keyword(s):  
Liquid Membrane ◽  
Specific Interaction ◽  
Pair Interaction ◽  
Hydroxyl Groups ◽  
Electrochemical Cells ◽  
Selective Electrode ◽  
Liquid Junction ◽  
Free Energy Of Transfer ◽  
Energy Of Transfer ◽  
Pair Interaction Parameter

The interaction of the two isomeric pentoses D-(−)-ribose and D-(−)-arabinose with the Ca2+ ion in aqueous solution is studied with the help of two types of electrochemical cells (with and without liquid junction) including a liquid-membrane Ca2+-selective electrode. Some of the D-(−)-ribose isomers contain a sequence of hydroxyl groups which can interact specifically with the cation. The measurement of the Gibbs free energy of transfer of Ca2+ between water and the sugar solutions allows one to calculate a characteristic pair-interaction parameter. This specific interaction can also be characterized by its association constant: β1 = 0.93. The two approaches are studied and their coherence is shown.

Heparin Counteracts the Antiaggregating Effect of Prostacyclin by Potentiating Platelet Aggregation

1983 ◽  
Vol 49 (02) ◽  
pp. 081-083 ◽  
Author(s):  
Vittorio Bertelé ◽  
Maria Carla Roncaglioni ◽  
Maria Benedetta Donati ◽  
Giovanni de Gaetano
Keyword(s):  
Platelet Aggregation ◽  
Human Platelet ◽  
Specific Interaction ◽  
Inhibitory Effect ◽  
Effective Inhibitor ◽  
Inhibitory Potency ◽  
Human Platelet Aggregation

SummaryIt has recently been reported that heparin neutralizes the inhibitory effect of prostacyclin (PGI2) on human platelet aggregation. The mechanism of this interaction has not yet been unequivocally established. We present here evidence that heparin (Liquemin Roche) does not react directly with PGI2 but counteracts its inhibitory effect by potentiating platelet aggregation. In the absence of heparin, PGI2 was a less effective inhibitor of platelet aggregation induced by the combination of ADP and serotonin than by ADP alone. Moreover, the inhibitory effect of PGI2 was similarly reduced when increasing the concentrations of ADP (in the absence of heparin). The lack of a specific interaction between heparin and PGI2 is supported by the observation that, in the presence of heparin, other prostaglandins such as PGD2 and PGE1, and a non-prostanoid compound such as adenosine also appeared to lose their inhibitory potency. It is concluded that heparin opposes platelet aggregation inhibitory effect of PGI2 by enhancement of platelet aggregation.

Bleaching ability of pre-hydrolyzed pulps in the context of a biorefinery mill

TAPPI Journal ◽  
2013 ◽  
Vol 12 (11) ◽  
pp. 49-53 ◽  
Author(s):  
CHRISTINE CHIRAT ◽  
LUCIE BOIRON ◽  
DOMINIQUE LACHENAL
Keyword(s):  
Carbon Content ◽  
Acid Hydrolysis ◽  
13C Nmr ◽  
Kraft Lignin ◽  
Kappa Number ◽  
Hydroxyl Groups ◽  
Kraft Pulps ◽  
Quaternary Carbon ◽  
Oxygen Delignification

Autohydrolysis and acid hydrolysis treatments were applied on mixed softwood chips. The cooking ability was studied by varying the alkali and duration of the cook. Pulps with kappa numbers varying from 30 to 70 were obtained. The bleaching ability of these pulps was studied and compared to control kraft pulps. The prehydrolyzed pulps were shown to be more efficiently delignified by oxygen than the control kraft pulps starting from the same kappa number. Furthermore, the final bleaching was also easier for these pulps. It was also shown that extensive oxygen delignification applied on high-kappa pre-hydrolyzed pulps could be a way to improve the overall yield, which is a prerequisite for the development of such biorefinery concepts. Lignin was isolated from the control kraft and the two pre-hydrolyzed kraft pulps and analyzed by 13C NMR. Lignins from pre-hydrolyzed kraft pulps had similar free phenolic groups content to the control kraft lignin, but their aliphatic hydroxyl groups and β-O-4 content were lower than for the control lignin. The quaternary carbon content was the same for all the samples.

Synthesis and antimicrobial properties of oligomeric silsesquioxanes containing quaternized nitrogen atoms and hydroxyl groups in organic shell

2017 ◽  
Vol 39 (3) ◽  
pp. 188-194
Author(s):  
M.A. Gumenna ◽  
◽  
N.S. Klimenko ◽  
A.V. Stryutsky ◽  
D.M. Hodyna ◽  
...  
Keyword(s):  
Antimicrobial Properties ◽  
Hydroxyl Groups ◽  
Organic Shell
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