Crystallization in Natural Rubber. V. Chemically Modified Rubber

1958 ◽  
Vol 31 (3) ◽  
pp. 519-525
Author(s):  
A. N. Gent
Keyword(s):  
Natural Rubber ◽  
Crystallization Process ◽  
Solid Phase ◽  
Quantitative Agreement ◽  
General Interest ◽  
Chemical Modifications ◽  
Chemically Modified ◽  
Chemical Combination ◽  
Final Extent ◽  
Thiol Acid

Abstract Small amounts of crosslinking have been shown to reduce the rate of crystallization of natural rubber by large factors. It has also been inferred from measurements on peroxide and sulfur vulcanizates of various kinds that sulfur combined in forms other than crosslinks may retard the crystallization process efficiently. A simple banned volume mechanism has been proposed to account for the influence of crosslinking and sidegroup combination on the rate and final extent of crystallization, and has been shown to predict the form of the observed dependences for crosslinked rubber, and approximately the relative magnitudes, but good quantitative agreement was not obtained. Measurements are described below of the rate and final extent of crystallization in natural rubber which has been modified by the chemical combination of sidegroups to the rubber molecule. It has not proved possible to account quantitatively for the observed rates of crystallization, but it is thought that a description of the extremely large effects found to accompany slight chemical modifications will be of general interest. The preparation of the modified rubbers is described elsewhere. The substances added were six thiol acids; namely, monochlorothiolacetic, trichlorothiolacetic, thiolbenzoic, 1-thiolnaphthoic, thiolsalicylic, and thiol-stearic acids. The reactions were carried out in the solid phase by addition of the thiol acid to purified rubber on an open mill, in solution by addition of the thiol acid to a solution of purified rubber in benzene, and in the latex phase.

Novel membranes from physico-chemically modified deproteinized natural rubber latex: development, characterisation and drug permeation

2018 ◽  
Vol 42 (17) ◽  
pp. 14179-14187
Author(s):  
Janisha Jayadevan ◽  
G. Unnikrishnan
Keyword(s):  
Drug Release ◽  
Natural Rubber ◽  
Natural Rubber Latex ◽  
Rubber Latex ◽  
Drug Permeation ◽  
Chemically Modified ◽  
Blend Membranes ◽  
Deproteinized Natural Rubber

Novel blend membranes from physico-chemically modified deproteinized natural rubber latex for drug release applications.

Evaluation of an enzyme immunoassay kit for estrogen receptor measurement--report II.

1988 ◽  
Vol 34 (10) ◽  
pp. 2053-2057 ◽  
Author(s):  
S Raam ◽  
D M Vrabel
Keyword(s):  
Enzyme Immunoassay ◽  
Binding Sites ◽  
Solid Phase ◽  
Functional Characterization ◽  
Quantitative Agreement ◽  
Type I ◽  
Type Ii ◽  
Immunoreactive Protein ◽  
Estrogen Binding

Abstract We present evidence to show that monoclonal antibodies to estrogen receptors (ER) in solid phase recognize the secondary estrogen binding sites with moderate to low affinity for estradiol (E2). An excellent quantitative agreement was found in five cytosols between the ER values obtained by the enzyme immunoassay (ER-EIA) and the amount of secondary estrogen binding sites measured by the assay involving dextran-coated charcoal (Clin Chem 1986;32:1496). The immunoreactive protein recognized by the antibody-coated beads, when allowed to react with ER(+) cytosols, is shown to bind [3H]estradiol only when the ligand concentration exceeds 8 nmol/L. Further biochemical and functional characterization of the immunoreactive protein is required to establish similarities/dissimilarities between this protein, high-affinity Type I ER sites, and the secondary sites such as Type II sites.

scholarly journals Simultaneous Determination of Synthetic Food Dyes Using a Single Cartridge for Preconcentration and Separation Followed by Photometric Detection

2020 ◽  
Vol 2020 ◽  
pp. 1-6 ◽  
Author(s):  
Elizaveta A. Rukosueva ◽  
Gulselem R. Aliyarova ◽  
Tatyana I. Tikhomirova ◽  
Vladimir V. Apyari ◽  
Pavel N. Nesterenko
Keyword(s):  
Spectrophotometric Determination ◽  
Solid Phase ◽  
Sunset Yellow ◽  
Photometric Detection ◽  
Chemically Modified ◽  
Relative Standard ◽  
Food Dyes ◽  
Quantitative Separation ◽  
Simultaneous Sorption

A novel preconcentration/separation method for simultaneous sorption-spectrophotometric determination of anionic food dyes Sunset Yellow and Tartrazine is proposed. The method is based on preconcentration of the dyes using solid phase extraction on a cartridge filled with silica chemically modified with C16 groups from aqueous solution at pH 1 followed by elution with water/acetonitrile mixture containing 2 mmol·L−1 KH2PO4 adjusted to pH 3 with a step gradient of acetonitrile content. This elution allows quantitative separation of the dyes which makes their individual spectrophotometric determination possible. The detection limits for Tartrazine and Sunset Yellow are 0.15 and 0.11 μg·mL−1 and the linearity range is 2–20 μg·mL−1. The method is applied for analysis of beverages. The recovery of dyes is higher than 97% at the relative standard deviation not exceeding 10%.

scholarly journals RNA Chemistry for RNA Biology

2019 ◽  
Vol 73 (5) ◽  
pp. 368-373 ◽  
Author(s):  
Pascal Röthlisberger ◽  
Christian Berk ◽  
Jonathan Hall
Keyword(s):  
Chemical Synthesis ◽  
Nucleic Acids ◽  
Chemical Biology ◽  
Rna Synthesis ◽  
Intrinsic Properties ◽  
Chemical Modifications ◽  
Chemically Modified ◽  
Wide Range ◽  
Rna Biology ◽  
Modified Nucleic Acids

Advances in the chemical synthesis of RNA have opened new possibilities to address current questions in RNA biology. Access to site-specifically modified oligoribonucleotides is often a pre-requisite for RNA chemical-biology projects. Driven by the enormous research efforts for development of oligonucleotide therapeutics, a wide range of chemical modifications have been developed to modulate the intrinsic properties of nucleic acids in order to fit their use as therapeutics or research tools. The RNA synthesis platform, supported by the NCCR RNA & Disease, aims to provide access to a large variety of chemically modified nucleic acids. In this review, we describe some of the recent projects that involved work of the platform and highlight how RNA chemistry supports new discoveries in RNA biology.

scholarly journals Interaction of methoxy- and methylenedioxyamphetamines with carbon and polymeric adsorbents in polar liquids

2010 ◽  
Vol 8 (4) ◽  
pp. 750-757
Author(s):  
Waldemar Tomaszewski ◽  
Vladimir Gun’ko ◽  
Roman Leboda ◽  
Jadwiga Skubiszewska-Zięba
Keyword(s):  
Free Energy ◽  
Surface Area ◽  
Surface Composition ◽  
Solid Phase ◽  
Chemical Compositions ◽  
Phase Extraction ◽  
Polar Liquids ◽  
Polymeric Adsorbents ◽  
Chemically Modified ◽  
Amphetamine Derivatives

AbstractSolid phase extraction (SPE) of methoxy- and methylenedioxyamphetamines from diluted aqueous solutions was investigated on carbon and polymeric adsorbents of different textures and chemical compositions. Those adsorbents were applied cartridges packed with three chemically modified carbons prepared from plum stones (initial A2PS, oxidized A2PS-O, and reduced A2PS-H) and commercially available adsorbents (polymeric LiChrolut EN, graphitized Hypercarb and Carboprep). Several factors influence the recovery rates of amphetamine derivatives such as the polarity of adsorbates (free energy of salvation), the specific surface area and surface composition of adsorbents, and the solvent characteristics. Different combinations of these factors affect the recovery rate (R1) for high- and low-surface area adsorbents. The minimal R1 values are observed for an amphetamine derivative at a maximal solvation effect and for a set of amphetamines adsorbed on graphitized carbons.

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