scholarly journals Biodegradation of low molecular weight polyacrylamide under aerobic and anaerobic conditions: effect of the molecular weight

2020 ◽  
Vol 81 (2) ◽  
pp. 301-308 ◽  
Author(s):  
Wenzhe Song ◽  
Yu Zhang ◽  
Amir Hossein Hamidian ◽  
Min Yang
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Carbon Chain ◽  
Anaerobic Treatment ◽  
Low Molecular Weight ◽  
Amino Groups ◽  
Molecular Weights ◽  
Weight One ◽  
Hydrolysis Of ◽  
Aerobic And Anaerobic

Abstract The biodegradation of polyacrylamide (PAM) includes the hydrolysis of amino groups and cleavage of the carbon chain; however, the effect of molecular weight on the biodegradation needs further investigations. In this study, biodegradation of low molecular weight PAM (1.6 × 106 Da) was evaluated in two aerobic (25 °C and 40 °C) and two anaerobic (35 °C and 55 °C) reactors over 100 days. The removal of the low molecular weight PAM (52.0–52.6%) through the hydrolysis of amino groups by anaerobic treatment (35 °C and 55 °C) was much higher than that of the high molecular weight (2.2 × 107 Da, 11.2–17.0%) observed under the same conditions. The molecular weight was reduced from 1.6 × 106 to 6.45–7.42 × 105 Da for the low molecular weight PAM, while the high molecular weight PAM declined from 2.2 × 107 to 3.76–5.87 × 106 Da. The results showed that the amino hydrolysis of low molecular weight PAM is easier than that of the high molecular weight one, while the cleavage of its carbon chain is still difficult. The molecular weights of PAM in the effluents from the two aerobic reactors (25 °C and 40 °C) were further reduced to 4.31 × 105 and 5.68 × 105 Da by the biofilm treatment, respectively. The results would be useful for the management of wastewater containing PAM.

scholarly journals Effects Of Environmental Factors On The Dispersion Behavior Of Iron Oxide In Aqueous Solutions With Poly Acrylic Acid

2015 ◽  
Vol 60 (2) ◽  
pp. 1561-1564
Author(s):  
E.-H. Lee ◽  
K.-M. Kim ◽  
W.-Y. Maeng ◽  
D.-H. Hur
Keyword(s):  
Molecular Weight ◽  
Acrylic Acid ◽  
High Molecular Weight ◽  
Low Molecular Weight ◽  
Solution Ph ◽  
Molecular Weights ◽  
Aqueous Suspensions ◽  
Magnetite Particles ◽  
The Stability ◽  
Poly Acrylic Acid

Abstract After preparing aqueous suspensions from magnetite particles with a poly-acrylic acid, we investigated the effects of several experimental parameters. We characterized the stability of the suspensions using visual inspection, sedimentation, adsorption, and thermal stability of the dispersant. The dispersion stability is affected by the solution pH, the concentrations of magnetite particles, the molecular weight, the concentration of the dispersants, and the temperature. The stability of the suspensions increased as the concentration of the dispersant and the temperature increased. In terms of the molecular weights of the dispersant, the suspensions with dispersant of low-molecular weight (1800) were more stable than those of high-molecular weight (250000) at room temperature. However, at high temperature the suspensions with high-molecular weight showed stability. The adsorption efficiency of the dispersant was very low. The dispersant of high-molecular weight showed a higher thermal integrity than that of low-molecular weight. From this work, we obtained the optimum conditions for stable aqueous suspensions of magnetite particles.

Analysis of proteins in rabbit pulmonary surfactant using monoclonal antibodies

1986 ◽  
Vol 250 (3) ◽  
pp. C460-C467 ◽  
Author(s):  
R. J. King ◽  
H. M. Martin ◽  
J. B. Baseman ◽  
J. Morrison-Plummer
Keyword(s):  
Molecular Weight ◽  
Monoclonal Antibodies ◽  
High Molecular Weight ◽  
Gel Electrophoresis ◽  
Pulmonary Surfactant ◽  
Polyacrylamide Gel Electrophoresis ◽  
Low Molecular Weight ◽  
Weight Group ◽  
Molecular Weights ◽  
Intermediate Group

We have used monoclonal antibodies developed against the apolipoproteins associated with pulmonary surfactant purified from rabbit lavage fluid to study the expression of epitopes common to these proteins. The pulmonary surfactant contained nearly 20 proteins, of which at least 10 were not derived from serum. Electrophoresis, with sulfhydryl reduction of these proteins indicated apparent molecular weights of approximately 155, 135, 125, and 115 X 10(3) (high-molecular-weight group); 80, 70, and 60 X 10(3) (intermediate group); and 18 through 10 X 10(3) (low-molecular-weight group). Two-dimensional polyacrylamide gel electrophoresis, in which the proteins were electrophoresed without reduction in the first dimension, but with sulfhydryl reduction in the second dimension, revealed that the 80, 70, and 60 X 10(3) proteins dissociated into proteins of nominal molecular weights of 40, 35, and 30 X 10(3), respectively. In contrast, the 125 and 115 X 10(3) proteins of the high-molecular-weight group contained a protein which could only be reduced to a minimum molecular weight of 55 to 60 X 10(3). Monoclonal antibodies generally were of three types: those that reacted strongly with the high-molecular-weight group and weakly with the intermediate group; those that reacted conversely; and those that reacted only with the low-molecular-weight group. Our results indicate that at least two different surfactant apolipoproteins, with differing minimum molecular weights in SDS-polyacrylamide gel electrophoresis, have common epitopes. Although these results cannot certify a physiological relationship between these proteins, they suggest that the intracellular synthesis or extracellular processing of surfactant apolipoproteins may be more complicated than predicted by the findings of previous experiments, perhaps involving the posttranslational assembly of one surfactant protein into oligomers which resist dissociation under the conditions used for the analyses.

Conditions Affecting the Molecular Weight of Factor VIII.

1979 ◽  
Author(s):  
G. Rock ◽  
E. Tackaberry ◽  
D. Palmer
Keyword(s):  
Molecular Weight ◽  
Factor Viii ◽  
High Molecular Weight ◽  
Calcium Concentration ◽  
Low Molecular Weight ◽  
Biochemical Purification ◽  
Molecular Weights ◽  
Will Self ◽  
And Storage ◽  
Molecular Weight Form

By purifying Factor VIII while maintaining physiological concentrations of calcium we have recently demonstrated that about 50% of the procoagulant activity is in a very low molecular weight (VLHW) form not associated with the carrier (VIII: RAG). The remainder is carrier associated and elutes at Vo as a high molecular weight (HMW) compound upon Sepharose 6B chromatography. Reduction of the calcium concentration by increasing the amount of citrate added to heparin results in decreasing the ratio of VLMW:HMW from 1:1 in pure heparin to 1:5 in pure citrate. If citrate is replaced with the more strongly chelating EDTA no VLMW is detectable in the plasma. It has also been found that most of the biochemical purification techniques which have been previously used to prepare Factor VIII for study actually result in the aggregation of this VLMW with the carrier to produce the high molecular weight form. This includes: cryoprecipitation, precipitation by polyethylene glycol and storage -80°C. As well, the VLMW material will self-associate upon freezing to produce an aggregate with a molecular weight of 106. However, this material does not cross-react with rabbit antibody directed against VIII: RAG. The data indicate that many of the previously reported biochemical characteristics, including molecular weights, actually describe species which are artifacts of the isolation process rather than those of the physiologically occuring Factor VIII.

Experimental Study on Flow-Front Fingering Instabilities in Injection Molding of Polymer Solutions and Melts

2004 ◽  
Author(s):  
Kalonji K. Kabanemi ◽  
Jean-Franc¸ois He´tu ◽  
Samira H. Sammoun
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Polymer Solutions ◽  
Low Molecular Weight ◽  
Flow Front ◽  
High Molecular Weight Polymer ◽  
Molecular Weight Polymer ◽  
Polymer Molecules ◽  
Molecular Weights ◽  
Solvent Molecules

An experimental investigation of the flow behavior of dilute, semi-dilute and concentrated polymer solutions has been carried out to gain a better understanding of the underlying mechanisms leading to the occurrence of instabilities at the advancing flow front during the filling of a mold cavity. Experiments were performed using various mass concentrations of low and high molecular weight polyacrylamide polymers in corn syrup and water. This paper reports a new type of elastic fingering instabilities at the advancing flow front that has been observed only in semi-dilute polymer solutions of high molecular weight polymers. These flow front elastic instabilities seem to arise as a result of a mixture of widely separated high molecular weight polymer molecules and low molecular weight solvent molecules, which gives rise to a largely non-uniform polydisperse solution, with respect to all the kinds of molecules in the resulting mixture (solvent molecules and polymer molecules). The occurrence of these instabilities appears to be independent of the injection flow rate and the cavity thickness. Moreover, these instabilities do not manifest themselves in dilute or concentrated regimes, where respectively, polymer molecules and solvent molecules are minor perturbation of the resulting solution. In those regimes, smooth flow fronts are confirmed from our experiments. Based on these findings, the experimental investigations have been extended to polymer melts. Different mixtures of polycarbonate melts of widely separated molecular weights (low and high molecular weights) were first prepared. The effect of the large polydispersity of the resulting mixtures on the flow front behavior was subsequently studied. The same instabilities at the flow front were observed only in the experiments where a very small amount of high molecular weight polycarbonate polymer has been mixed to a low molecular weight polycarbonate melt (oligomers).

scholarly journals Fire Resistance, Thermal and Anti-Ageing Properties of Transparent Fire-Retardant Coatings Modified with Different Molecular Weights of Polyethylene Glycol Borate

Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4206
Author(s):  
Long Yan ◽  
Xinyu Tang ◽  
Xiaojiang Xie ◽  
Zhisheng Xu
Keyword(s):  
Molecular Weight ◽  
Polyethylene Glycol ◽  
High Molecular Weight ◽  
Fire Resistance ◽  
Fire Retardant ◽  
Phosphate Ester ◽  
Low Molecular Weight ◽  
Molecular Weights ◽  
Flame Retarded ◽  
Residual Weight

Four kinds of polyethylene glycol borate (PEG-BA) with different molecular weights were grafted into cyclic phosphate ester (PEA) to obtain flexible phosphate esters (PPBs), and then applied in amino resin to obtain a series of transparent intumescent fire-retardant coatings. The comprehensive properties of the transparent coatings containing different molecular weights of PEG-BA were investigated by various analytical instruments. The transparency and mechanical analyses indicate that the presence of PEG-BA slightly decreases the optical transparency of the coatings but improves the flexibility and adhesion classification of the coatings. The results from fire protection and cone calorimeter tests show that low molecular weight of PEG-BA exerts a positive flame-retarded effect in the coatings, while high molecular weight of PEG800-BA behaves against flame-retarded effect. Thermogravimetric and char residue analyses show that the incorporation of low molecular weight of PEG-BA clearly increases the thermal stability and residual weight of the coatings and generates a more compact and stable intumescent char on the surface of the coatings, thus resulting in superior synergistic flame-retarded effect. In particular, MPPB1 coating containing PEG200-BA exerts the best flame-retarded effect and highest residual weight of 36.3% at 700 °C, which has 57.6% reduction in flame spread rate and 23.9% reduction in total heat release compared to those of MPPB0 without PEG-BA. Accelerated ageing test shows that low molecular weight of PEG-BA promotes to enhance the durability of structural stability and fire resistance of the coatings, while PEG800-BA with high molecular weight weakens the ageing resistance. In summary, the fire-resistant and anti-ageing efficiencies of PEG-BA in the coatings depend on its molecular weight, which present the order of PEG200-BA > PEG400-BA > PEG600-BA > PEG800-BA.

Variability of Low-Molecular-Weight, Heat-Modifiable Outer Membrane Proteins of Neisseria meningitidis

1980 ◽  
Vol 30 (3) ◽  
pp. 642-648
Author(s):  
J. T. Poolman ◽  
S. De Marie ◽  
H. C. Zanen
Keyword(s):  
Molecular Weight ◽  
Outer Membrane ◽  
High Molecular Weight ◽  
Outer Membrane Proteins ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Low Molecular Weight ◽  
Molecular Weights ◽  
Sds Page ◽  
Index Cases

Analysis of major outer membrane protein (MOMP) profiles of various meningococci by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (SDS-PAGE) revealed the presence of 0 to 2 low-molecular-weight, heat-modifiable MOMPs (molecular weight, 25,000 to 32,000) and 1 to 3 high-molecular-weight MOMPs (molecular weight, 32,000 to 46,000). Heat modifiability was investigated by comparing MOMP profiles after heating in SDS solutions at 100°C for 5 min or at 40°C for 1 h. Low-molecular-weight MOMPs shifted to higher apparent molecular weights after being heated at 100°C. Heat modifiability of high-molecular-weight MOMPs varied among strains; whenever modified these proteins shifted to lower apparent molecular weights after complete denaturation. Variability of low-molecular-weight, heat-modifiable MOMPs was demonstrated when MOMP profiles were compared of (i) isolates from index cases and associated cases and carriers among contacts, (ii) different isolates from the same individual, and (iii) isolates from a small epidemic caused by serogroup W-135. In some cases high-molecular-weight MOMPs revealed quantitative differences among related strains. The observed variability and quantitative differences indicate that MOMP serotyping and typing on the basis of SDS-PAGE profiles (PAGE typing) need careful reevaluation.

Fracture Toughness of Epoxy Resins Containing Blends of Monomers with Different Molecular Weights

2007 ◽  
Vol 345-346 ◽  
pp. 1511-1514 ◽  
Author(s):  
Andi Haris ◽  
Tadaharu Adachi ◽  
Wakako Araki ◽  
Yu Hayashi
Keyword(s):  
Fracture Toughness ◽  
Molecular Weight ◽  
High Molecular Weight ◽  
Weight Ratio ◽  
Crosslinking Degree ◽  
Molecular Weights ◽  
Epoxy Monomer ◽  
Weight One ◽  
Simultaneous Decrease

The effect of adding a high molecular weight epoxy monomer (epikote 1001) to a low molecular weight one (epikote 828) on fracture toughness properties was investigated according to the crosslinking degree and density heterogeneity. To characterize the crosslinking degree and density heterogeneity, the glass transition temperature, Tg, and fragility, m, were deduced from thermo-viscoelastic properties. The characterization of Tg and m revealed that blends can be divided into two groups: one group with (φ < 10 wt%) and another one with (φ > 10 wt%), where φ is the weight ratio of epikote 1001 to epikote 828. The first group had the same average crosslinking degree (the same Tg) but different density heterogeneities (m decreased). The other group had a lower crosslinking degree (Tg decreased) and even more density heterogeneity (m decreased). The fracture toughness results showed that KIC of blends of the first group was approximately constant because the increase in density heterogeneity was still too weak (ineffective m), whereas KIC of blends of the second group was higher due to the simultaneous decrease in average crosslinking degree and increase in density heterogeneity. Therefore, the lower crosslinking degree (lower Tg) is and the more heterogeneous the blend (lower m) is due to the addition of high molecular weight monomer, the higher KIC becomes.

scholarly journals When Attempting Chain Extension, Even Without Solvent, It Is Not Possible to Avoid Chojnowski Metathesis Giving D3

Molecules ◽  
2021 ◽  
Vol 26 (1) ◽  
pp. 231
Author(s):  
Mengchen Liao ◽  
Yang Chen ◽  
Michael A. Brook
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Efficient Method ◽  
Heterogeneous Reaction ◽  
Chain Extension ◽  
Molecular Weights ◽  
Second Growth ◽  
The One ◽  
Hydrolysis Of ◽  
Homogeneous Reactions

A simple, mild and efficient method to prepare HSi- or HOSi-telechelic, high-molecular-weight polydimethylsiloxane polymers (to 41,600 g·mol−1) using the one-shot hydrolysis of MHMH is reported; titration of the water allowed for higher molecular weights (to 153,900 g·mol−1). The “living” character of the chain extension processes was demonstrated by adding a small portion of MHMH and B(C6F5)3 (BCF) to a first formed polymer, which led to a ~2-fold, second growth in molecular weight. The heterogeneous reaction reached completion in less than 30 min, much less in some cases, regardless of whether it was performed neat or 50 wt% in dry toluene; homogeneous reactions in toluene were much slower. The process does not involve traditional redistribution, as judged by the low quantities (<3%) of D4 produced. However, it is not possible to avoid Chojnowski metathesis from MHDDMH giving D3, which occurs competitively with chain extension.

scholarly journals Fabrication of a High-Performance Bending Actuator Made with a PVC Gel

2018 ◽  
Vol 8 (8) ◽  
pp. 1284 ◽  
Author(s):  
Eun-Jae Shin ◽  
Won-Hyeong Park ◽  
Sang-Youn Kim
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
High Performance ◽  
Low Molecular Weight ◽  
Bending Angle ◽  
Bending Performance ◽  
Molecular Weights ◽  
Elapsed Time ◽  
Poly Vinyl Chloride ◽  
Bending Actuator

This paper proposes a small, transparent, electroactive and highly deformable poly vinyl chloride (PVC) gel-based bending actuator. The effect of the PVC molecular weight and plasticizer content on the performance of the bending actuator is investigated. Three PVCs are prepared with different molecular weights (low molecular weight: PVCL, 116,000; medium molecular weight: PVCM, 239,000; and high molecular weight: PVCH, 282,000) and mixed with plasticizers in various ratios to achieve the best performance of the bending actuator. Experiments are conducted to investigate the bending performance of the actuators based on the prepared PVC gels. Among the prepared actuators, the PVCH-based bending actuator shows the best performance (maximum bending angle: 180°, elapsed time: 3.15 s).

scholarly journals Synthesis of High Molecular Weight Chitosan from Chitin by Mechanochemistry and Aging

2019 ◽  
Author(s):  
Thomas Di Nardo ◽  
Caroline Hadad ◽  
Albert Nguyen Van Nhien ◽  
Audrey Moores
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Magic Angle Spinning ◽  
Low Molecular Weight ◽  
Magic Angle ◽  
Energy Usage ◽  
Molecular Weights ◽  
Low Molecular Weight Chitosan ◽  
Angle Spinning ◽  
High Molecular Weight Chitosan

Chitosan can be obtained from the deacetylation of chitin. This process is however difficult and usually accompanied by depolymerization, affording low molecular weight chitosan. We report a novel path, relying on a combination of mechanochemitry and aging, to afford high molecular weight chitosan with minimal use of energy and solvent. This method is versatile and applicable to a number of chitin sources, including crude crustaceans and insect shells, yielding deacetylation up to 98% and remarkably high molecular weights. Chitin deacetylation was measured by magic angle spinning nuclear magnetic resonance and molecular weight by viscometry. This process affords chitosan in a safer fashion and with less materials and energy usage than the classic hydrothermal one.

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