scholarly journals Formation of Microfiltration Membranes from PMP/PIB Blends: Effect of PIB Molecular Weight on Membrane Properties

Membranes ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 9 ◽  
Author(s):  
Sergey Ilyin ◽  
Viktoria Ignatenko ◽  
Tatyana Anokhina ◽  
Danila Bakhtin ◽  
Anna Kostyuk ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Porous Structure ◽  
Membrane Properties ◽  
Retention Performance ◽  
Sem Images ◽  
Immiscible Blends ◽  
Molecular Weights ◽  
Flat Sheet ◽  
Optimal Filtration ◽  
Microfiltration Membranes

A series of microfiltration membranes were fabricated by the extraction of polyisobutylene (PIB) from its immiscible blends with polymethylpentene (PMP). Three PIB with different molecular weight of 7.5 × 104 (Oppanol B15), 34 × 104 (Oppanol B50) and 110 × 104 (Oppanol B100) g/mol, respectively, were used to evaluate the effect of molecular weight on the porous structure and transport properties of resulting PMP-based membranes. To mimic the conditions of 3D printing, the flat-sheet membranes were fabricated by means of melting of mixtures of various PMP and PIB concentrations through the hot rolls at 240 ∘ C followed by a quick cooling. The rheology study of individual components and blends at 240 ∘ C revealed that PIB B50 possessed the most close flow curve to the pure PMP, and their blends demonstrated the lowest viscosity comparing to the compositions made of PIB with other molecular weights (B15 or B100). SEM images of the cross-section PMP membranes after PIB extraction (PMP/PIB = 55/45) showed that the use of PIB B50 allowed obtaining the sponge-like porous structure, whereas the slit-shaped pores were found in the case of PIB B15 and PIB B100. Additionally, PMP/B50 blends demonstrated the optimum combinations of mechanical properties (str = 9.1 MPa, E = 0.20 GPa), adhesion to steel (adh = 0.8 kPa) and retention performance (R240 nm = 99%, R38 nm = 39%). The resulting membranes were non- or low-permeable for water if the concentration of PIB B50 in the initial blends was 40 wt.% or lower. The optimal filtration performance was observed in the case of PMP/B50 blends with a ratio of 55/45 (Pwater = 1.9 kg/m2hbar, R240 nm = 99%, R38 nm = 39%) and 50/50 (Pwater = 1100 kg/m2hbar, R240 nm = 91%, R38 nm = 36%).

The effect of various retention aids on retention and formation

2010 ◽  
Vol 25 (2) ◽  
pp. 195-203 ◽  
Author(s):  
Anna Svedberg ◽  
Tom Lindström
Keyword(s):  
Molecular Weight ◽  
Single Component ◽  
Retention Performance ◽  
Total Solids ◽  
Cationic Polyacrylamide ◽  
Molecular Weights ◽  
Different Types ◽  
Retention Aids ◽  
Solids Content

Abstract The interdependency between retention and paper formation was studied using a previously designed R-F (Retention and formation)-machine. The objective of the work was to investigate the retentionformation relationship for different types of retention aid systems. Both single-component cationic polyacrylamides with varying molecular weights and polyacrylamide- based microparticulate retention aids were investigated on the R-F-machine, for a fine paper stock with addition of 25% filler (based on total solids content). Results showed that the retention-formation relationship was not dependent on the retention aid systems used, since all systems provided similar relationships. In terms of the retention performance, significant differences were observed, depending on the choice of microparticle system and molecular weight of the used cationic polyacrylamide.

Investigation by HPLC of the Catabolism of Recombinant Tissue Plasminogen Activator in the Rat

1988 ◽  
Vol 60 (01) ◽  
pp. 107-112 ◽  
Author(s):  
Roy Harris ◽  
Louis Garcia Frade ◽  
Lesley J Creighton ◽  
Paul S Gascoine ◽  
Maher M Alexandroni ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Plasminogen Activator ◽  
Tissue Plasminogen Activator ◽  
Half Life ◽  
Recombinant Tissue Plasminogen Activator ◽  
Rat Plasma ◽  
High Molecular Weight Complex ◽  
Molecular Weights ◽  
Major Activity ◽  
Tissue Plasminogen

SummaryThe catabolism of recombinant tissue plasminogen activator (rt-PA) was investigated after injection of radiolabelled material into rats. Both Iodogen and Chloramine T iodination procedures yielded similar biological activity loss in the resultant labelled rt-PA and had half lives in the rat circulation of 1 and 3 min respectively. Complex formation of rt-PA was investigated by HPLC gel exclusion (TSK G3000 SW) fractionation of rat plasma samples taken 1-2 min after 125I-rt-PA injection. A series of radiolabelled complexes of varying molecular weights were found. However, 60% of the counts were associated with a single large molecular weight complex (350–500 kDa) which was undetectable by immunologically based assays (ELISA and BIA) and showed only low activity with a functional promoter-type t-PA assay. Two major activity peaks in the HPLC fractions were associated with Tree t-PA and a complex having a molecular weight of ̴ 180 kDa. HPLC fractionation to produce these three peaks at various timed intervals after injection of 125I-rt-PA showed each to have a similar initial rate half life in the rat circulation of 4-5 min. The function of these complexes as yet is unclear but since a high proportion of rt-PA is associated with a high molecular weight complex with a short half life in the rat, we suggest that the formation of this complex may be a mechanism by which t-PA activity is initially regulated and finally cleared from the rat circulation.

Permeability Enhancing and Chemotactic Activities of Lower Molecular Weight Degradation Products of Human Fibrinogen

1981 ◽  
Vol 45 (01) ◽  
pp. 090-094 ◽  
Author(s):  
Katsuo Sueishi ◽  
Shigeru Nanno ◽  
Kenzo Tanaka
Keyword(s):  
Molecular Weight ◽  
Degradation Products ◽  
Electron Microscopic Observation ◽  
Chemotactic Activity ◽  
Lower Molecular Weight ◽  
Electron Microscopic ◽  
Human Fibrinogen ◽  
Rabbit Skin ◽  
Molecular Weights ◽  
Active Fragments

SummaryFibrinogen degradation products were investigated for leukocyte chemotactic activity and for enhancement of vascular permeability. Both activities increased progressively with plasmin digestion of fibrinogen. Active fragments were partially purified from 24 hr-plasmin digests. Molecular weights of the permeability increasing and chemotactic activity fractions were 25,000-15,000 and 25,000 respectively. Both fractions had much higher activities than the fragment X, Y, D or E. Electron microscopic observation of the small blood vessels in rabbit skin correlated increased permeability with the formation of characteristic gaps between adjoining endothelial cells and their contraction.These findings suggest that lower molecular weight degradation products of fibrinogen may be influential in contributing to granulocytic infiltration and enhanced permeability in lesions characterized by deposits of fibrin and/or fibrinogen.

Toxicity of Heparinoids, with Special Reference to the Precipitation of Fibrinogen

1964 ◽  
Vol 12 (01) ◽  
pp. 232-261 ◽  
Author(s):  
S Sasaki ◽  
T Takemoto ◽  
S Oka
Keyword(s):  
Molecular Weight ◽  
Dextran Sulfate ◽  
Anticoagulant Activity ◽  
Molecular Structures ◽  
Severe Reaction ◽  
Clinical Use ◽  
Molecular Weights ◽  
Close Relationship

SummaryTo demonstrate whether the intravascular precipitation of fibrinogen is responsible for the toxicity of heparinoid, the relation between the toxicity of heparinoid in vivo and the precipitation of fibrinogen in vitro was investigated, using dextran sulfate of various molecular weights and various heparinoids.1. There are close relationships between the molecular weight of dextran sulfate, its toxicity, and the quantity of fibrinogen precipitated.2. The close relationship between the toxicity and the precipitation of fibrinogen found for dextran sulfate holds good for other heparinoids regardless of their molecular structures.3. Histological findings suggest strongly that the pathological changes produced with dextran sulfate are caused primarily by the intravascular precipitates with occlusion of the capillaries.From these facts, it is concluded that the precipitates of fibrinogen with heparinoid may be the cause or at least the major cause of the toxicity of heparinoid.4. The most suitable molecular weight of dextran sulfate for clinical use was found to be 5,300 ~ 6,700, from the maximum value of the product (LD50 · Anticoagulant activity). This product (LD50 · Anticoagulant activity) can be employed generally to assess the comparative merits of various heparinoids.5. Clinical use of the dextran sulfate prepared on this basis gave satisfactory results. No severe reaction was observed. However, two delayed reactions, alopecia and thrombocytopenia, were observed. These two reactions seem to come from the cause other than intravascular precipitation.

Molecular Weights of Factor VIII (AHF) and Factor IX (PTC) by Electron Irradiation

1962 ◽  
Vol 08 (02) ◽  
pp. 270-275 ◽  
Author(s):  
David L Aronson ◽  
John W Preiss ◽  
Michael W Mosesson
Keyword(s):  
Molecular Weight ◽  
Factor Viii ◽  
Electron Irradiation ◽  
Factor Ix ◽  
Molecular Weights

SummaryThe molecular weights of AHF (factor VIII) and of PTC (factor IX) have been estimated by their sensitivity to inactivation by 7 kilovolt electrons. The molecular weight of AHF was found to be 180 000 by this method and that of PTC was found to be 110 000.

scholarly journals Effects of Molecular Weight of Functionalized Liquid Butadiene Rubber as a Processing Aid on the Properties of SSBR/Silica Compounds

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 850
Author(s):  
Donghyuk Kim ◽  
Byungkyu Ahn ◽  
Kihyun Kim ◽  
JongYeop Lee ◽  
Il Jin Kim ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Anionic Polymerization ◽  
High Performance ◽  
Crosslink Density ◽  
Functional Group ◽  
Vital Role ◽  
Butadiene Rubber ◽  
Molecular Weights ◽  
Mooney Viscosity ◽  
Silica Dispersion

Liquid butadiene rubber (LqBR) which used as a processing aid play a vital role in the manufacturing of high-performance tire tread compounds. However, the studies on the effect of molecular weight, microstructure, and functionalization of LqBR on the properties of compounds are still insufficient. In this study, non-functionalized and center-functionalized liquid butadiene rubbers (N-LqBR and C-LqBR modified with ethoxysilyl group, respectively) were synthesized with low vinyl content and different molecular weights using anionic polymerization. In addition, LqBR was added to the silica-filled SSBR compounds as an alternative to treated distillate aromatic extract (TDAE) oil, and the effect of molecular weight and functionalization on the properties of the silica-filled SSBR compound was examined. C-LqBR showed a low Payne effect and Mooney viscosity because of improved silica dispersion due to the ethoxysilyl functional group. Furthermore, C-LqBR showed an increased crosslink density, improved mechanical properties, and reduced organic matter extraction compared to the N-LqBR compound. LqBR reduced the glass transition temperature (Tg) of the compound significantly, thereby improving snow traction and abrasion resistance compared to TDAE oil. Furthermore, the energy loss characteristics revealed that the hysteresis loss attributable to the free chain ends of LqBR was dominant.

scholarly journals Nuclear matrix of HeLa S3 cells. Polypeptide composition during adenovirus infection and in phases of the cell cycle.

1977 ◽  
Vol 72 (1) ◽  
pp. 194-208 ◽  
Author(s):  
L D Hodge ◽  
P Mancini ◽  
F M Davis ◽  
P Heywood
Keyword(s):  
Cell Cycle ◽  
Molecular Weight ◽  
Nuclear Matrix ◽  
Apparent Molecular Weight ◽  
Molecular Weight Range ◽  
Weight Range ◽  
Molecular Weights ◽  
Liver Nuclei ◽  
Hela S3 ◽  
Biochemical Analyses

A subnuclear fraction has been isolated from HeLa S3 nuclei after treatment with high salt buffer, deoxyribonuclease, and dithiothreitol. This fraction retains the approximate size and shape of nuclei and resembles the nuclear matrix recently isolated from rat liver nuclei. Ultrastructural and biochemical analyses indicate that this structure consists of nonmembranous elements as well as some membranous elements. Its chemical composition is 87% protein, 12% phospholipid, 1% DNA, and 0.1% RNA by weight. The protein constituents are resolved in SDS-polyacrylamide slab gels into 30-35 distinguishable bands in the apparent molecular weight range of 14,000 - 200,000 with major peptides at 14,000 - 18,000 and 45,000 - 75,000. Analysis of newly synthesized polypeptides by cylindrical gel electrophoresis reveals another cluster in the 90,000-130,000 molecular weight range. Infection with adenovirus results in an altered polypeptide profile. Additional polypeptides with apparent molecular weights of 21,000, 23,000, and 92,000 become major components by 22 h after infection. Concomitantly, some peptides in the 45,000-75,000 mol wt range become less prominent. In synchronized cells the relative staining capacity of the six bands in the 45,000-75,000 mol wt range changes during the cell cycle. Synthesis of at least some matrix polypeptides occures in all phases of the cell cycle, although there is decreased synthesis in late S/G2. In the absence of protein synthesis after cell division, at least some polypeptides in the 45,000-75,000 mol wt range survive nuclear dispersal and subsequent reformation during mitosis. The possible significance of this subnuclear structure with regard to structure-function relationships within the nucleus during virus replication and during the life cycle of the cell is discussed.

scholarly journals Design of Aerogels, Cryogels and Xerogels of Alginate: Effect of Molecular Weight, Gelation Conditions and Drying Method on Particles’ Micromeritics

Molecules ◽  
2019 ◽  
Vol 24 (6) ◽  
pp. 1049 ◽  
Author(s):  
Rosalía Rodríguez-Dorado ◽  
Clara López-Iglesias ◽  
Carlos García-González ◽  
Giulia Auriemma ◽  
Rita Aquino ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Physicochemical Properties ◽  
Textural Properties ◽  
Supercritical Drying ◽  
Processing Parameters ◽  
Storage Conditions ◽  
Drying Methods ◽  
Drying Method ◽  
Molecular Weights ◽  
Nanostructured Particles

Processing and shaping of dried gels are of interest in several fields like alginate aerogel beads used as highly porous and nanostructured particles in biomedical applications. The physicochemical properties of the alginate source, the solvent used in the gelation solution and the gel drying method are key parameters influencing the characteristics of the resulting dried gels. In this work, dried gel beads in the form of xerogels, cryogels or aerogels were prepared from alginates of different molecular weights (120 and 180 kDa) and concentrations (1.25, 1.50, 2.0 and 2.25% (w/v)) using different gelation conditions (aqueous and ethanolic CaCl2 solutions) and drying methods (supercritical drying, freeze-drying and oven drying) to obtain particles with a broad range of physicochemical and textural properties. The stability of physicochemical properties of alginate aerogels under storage conditions of 25 °C and 65% relative humidity (ICH-climatic zone II) during 1 and 3 months was studied. Results showed significant effects of the studied processing parameters on the resulting alginate dried gel properties. Stability studies showed small variations in aerogels weight and specific surface area after 3 months of storage, especially, in the case of aerogels produced with medium molecular weight alginate.

Relation between Molecular Weights and Physical Properties of Rubber Fractions

1941 ◽  
Vol 14 (3) ◽  
pp. 580-589 ◽  
Author(s):  
G. Gee ◽  
L. R. G. Treloar
Keyword(s):  
Molecular Weight ◽  
Natural Rubber ◽  
Physical Properties ◽  
High Molecular Weight ◽  
Elastic Properties ◽  
Elastic Material ◽  
Experimental Results ◽  
Molecular Weights ◽  
High Elasticity ◽  
Latex Rubber

Abstract As high elasticity is a property possessed only by substances of high molecular weight, it is of interest to enquire into the relation between the elastic properties of a highly elastic material such as rubber and its molecular weight. An investigation on these lines has been made possible through the work of Bloomfield and Farmer, who have succeeded in separating natural rubber into fractions having different average molecular weights. The more important physical properties of these fractions have been examined with the object of determining which of the properties are dependent on molecular weight and which are not. Fairly extensive observations were made on the fractions from latex rubber referred to as Nos. 2, 3 and 4 by Bloomfield and Farmer, and some less extensive observations were carried out on the less oxygenated portion of fraction No. 1 obtained from crepe rubber (called hereafter 1b) . Before considering these experimental results, and their relation to the molecular weights of the fractions, it will be necessary to refer briefly to the methods used for the molecular-weight determinations, and to discuss the significance of the figures obtained.

Sign in / Sign up

Export Citation Format

Share Document