scholarly journals Fluorescent Characteristics and Metal Binding Properties of Different Molecular Weight Fractions in Stratified Extracellular Polymeric Substances of Activated Sludge

Separations ◽  
2021 ◽  
Vol 8 (8) ◽  
pp. 120
Author(s):  
Jingwen Lian ◽  
Yang Yang ◽  
Weiyi Qiu ◽  
Lijie Huang ◽  
Chuanhua Wang ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Molecular Weight ◽  
Activated Sludge ◽  
Metal Binding ◽  
Extracellular Polymeric Substances ◽  
Three Dimensional ◽  
Fluorescence Analysis ◽  
Quenching Effect ◽  
Molecular Weights ◽  
Different Molecular Weight

The combination of heavy metals and extracellular polymeric substances (EPSs) affects the distribution of heavy metals in microbial aggregates, soil, and aquatic systems. This paper aimed to explore the binding mechanisms of EPSs of different molecular weights in activated sludge with heavy metals. We extracted the stratification components of activated sludge EPSs and divided the components into five fractions of different molecular weight ranges. In the three-dimensional fluorescence analysis of each fraction, the EPSs of activated sludge had two peaks, peak A (representing low-excitation tryptophan) and peak B (representing high-excitation tryptophan), and static quenching was the main reason for the fluorescence quenching between the compounds attributable to peak A in activated sludge EPSs and Pb2+ and Cu2+. Further exploration suggested that the EPSs of activated sludge interacted with Cd2+, Pb2+, Cu2+, and Zn2+ to form new substances. The quenching effect of the EPSs with the highest molecular weight (100 kDa–0.7 μm) was more significant, and the binding ability was more stable. This study implies that the application of EPSs from activated sludge is promising. While effectively binding heavy metals, it can also reduce the volume of the excess activated sludge.

Isolation of copper-binding proteins from activated sludge culture

2001 ◽  
Vol 44 (2-3) ◽  
pp. 453-459 ◽  
Author(s):  
K. Fukushi ◽  
S. Kato ◽  
T. Antsuki ◽  
T. Omura
Keyword(s):  
Molecular Weight ◽  
Activated Sludge ◽  
Metal Uptake ◽  
Binding Proteins ◽  
Growth Media ◽  
Copper Binding ◽  
Molecular Weights ◽  
Binding Capability ◽  
Copper Binding Proteins

Six copper-binding microbial proteins were isolated from activated sludge cultures grown on media containing copper at various concentrations. Molecular weights among isolated proteins were ranged from 1.3k to 174k dalton. Isolated proteins were compared for their copper binding capabilities. Proteins isolated from cultures grown in the presence of copper in the growth media exhibited higher copper binding capabilities than those isolated from the culture grown in the absence of copper. The highest metal uptake of 61.23 (mol copper/mol protein) was observed by a protein isolated from a culture grown with copper at a concentration of 0.25 mM. This isolated protein (CBP2) had a molecular weight of 24k dalton. Other protein exhibited copper binding capability of 4.8-32.5 (mol copper/mol protein).

Kinetics and fundamental mechanisms of starch removal by activated sludge: hydrolysis of starch to maltose and maltotriose is the rate-determining step

1999 ◽  
Vol 40 (1) ◽  
pp. 61-68 ◽  
Author(s):  
Y. Ubukata
Keyword(s):  
Molecular Weight ◽  
Activated Sludge ◽  
Removal Rates ◽  
Molecular Weights ◽  
Rate Determining Step ◽  
Molecular Weight Distributions ◽  
Uptake Rates ◽  
Weight Distributions ◽  
Sludge Hydrolysis ◽  
Hydrolysis Of

The mechanisms of hydrolysis and uptake of starch, a polymer in sewage, by activated sludge (AS) were investigated, taking into consideration the mechanisms of the maltose transport system, responsible for the uptake of hydrolysis products of starch, in Gram-negative bacteria. AS was acclimated to dextrin, and the molecular weight distributions of the substrates during dextrin removal are analyzed using a GPC method. The removal rates of substrates such as dextrin, various maltodextrins (maltotriose, etc.), maltose and glucose by AS, and the oxygen uptake rates (OURs) of AS during the removal of these substrates were compared. Low-molecular-weight saccharides such as glucose, maltose and maltotriose were undetectable in the substrates during dextrin removal. The removal rates of maltose and maltotriose were higher than those of dextrin and glucose, and the OURs of AS during the removal of maltose and maltotriose were higher than those for other substrates. Therefore, hydrolysis of starch to maltose (dimer) and maltotriose (trimer), and not to glucose (monomer), appears to be the rate-determining step during the removal of starch, although maltodextrins with molecular weights up to 1152 (maltoheptaose) appear to penetrate the bacterial outer membrane.

Three-dimensional excitation emission matrix fluorescence spectroscopy and gel-permeating chromatography to characterize extracellular polymeric substances in aerobic granulation

2010 ◽  
Vol 61 (11) ◽  
pp. 2931-2942 ◽  
Author(s):  
Huacheng Xu ◽  
Pinjing He ◽  
Guanzhao Wang ◽  
Liming Shao
Keyword(s):  
Molecular Weight ◽  
Fluorescence Spectroscopy ◽  
Extracellular Polymeric Substances ◽  
Operating Time ◽  
Three Dimensional ◽  
Aerobic Granules ◽  
Aerobic Granulation ◽  
Excitation Emission Matrix ◽  
Two Peaks ◽  
Eem Fluorescence

Three-dimensional excitation emission matrix (EEM) fluorescence spectroscopy and gel-permeating chromatography (GPC) were employed to characterize the extracellular polymeric substances (EPS) in aerobic granulation. EPS matrix in this study was stratified into four fractions: (1) supernatant, (2) slime, (3) loosely bound EPS (LB-EPS), and (4) tightly bound EPS (TB-EPS). The results showed that the dissolved organic carbon was mainly distributed in TB-EPS fraction, and increased with increasing the operating time. The supernatant, slime, and LB-EPS fractions exhibited four fluorescence peaks, an autochthonous signature, unimodal MW distribution and lower molecular weight (MW) (3 < log [MW]<5), whereas the TB-EPS fraction only had two peaks, an allochthonous signature, multiple peaks and higher MW (5 < log [MW]<7). It was deemed that the formation of aerobic granules was correlated with the accumulation of proteins in the TB-EPS fraction. EEM spectroscopy and GPC profiles could be used as appropriate and effective methods to characterize the EPS in aerobic granulation from a micro-view level.

Heavy metal-binding proteins from metal-stimulated bacteria as a novel adsorbent for metal removal technology

2006 ◽  
Vol 53 (6) ◽  
pp. 221-226 ◽  
Author(s):  
D. Sano ◽  
K. Myojo ◽  
T. Omura
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Activated Sludge ◽  
Metal Binding ◽  
Binding Proteins ◽  
Metal Removal ◽  
Heavy Metal Removal ◽  
Copper Ion ◽  
Amino Acid Sequences ◽  
Heavy Metal Binding

Water pollution with toxic heavy metals is of growing concern because heavy metals could bring about serious problems for not only ecosystems in the water environment but also human health. Some metal removal technologies have been in practical use, but much energy and troublesome treatments for chemical wastes are required to operate these conventional technologies. In this study, heavy metal-binding proteins (HMBPs) were obtained from metal-stimulated activated sludge culture with affinity chromatography using copper ion as a ligand. Two-dimensional electrophoresis revealed that a number of proteins in activated sludge culture were recovered as HMBPs for copper ion. N-termini of five HMBPs were determined, and two of them were found to be newly discovered proteins for which no amino acid sequences in protein databases were retrieved at more than 80% identities. Metal-coordinating amino acids occupied 38% of residues in one of the N-terminal sequences of the newly discovered HMBPs. Since these HMBPs were expected to be stable under conditions of water and wastewater treatments, it would be possible to utilize HMBPs as novel adsorbents for heavy metal removal if mass volume of HMBPs can be obtained with protein cloning techniques.

scholarly journals Penetration Efficiency of Antitumor Agents in Ovarian Cancer Spheroids: The Case of Recombinant Targeted Toxin DARPin-LoPE and the Chemotherapy Drug, Doxorubicin

Pharmaceutics ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 219 ◽  
Author(s):  
Evgeniya Sokolova ◽  
Olga Kutova ◽  
Alena Grishina ◽  
Anton Pospelov ◽  
Evgeniy Guryev ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Antitumor Agents ◽  
Three Dimensional ◽  
Growth Factor Receptor ◽  
Ovarian Adenocarcinoma ◽  
Chemotherapy Drug ◽  
Molecular Weights ◽  
Epidermal Growth ◽  
Cancer Spheroids ◽  
Targeted Toxin

The efficiency of delivering a therapeutic agent into a tumor is among the crucial factors determining the prospects for its clinical use. This problem is particularly acute in the case of targeted antitumor agents since many of them are high-molecular-weight compounds. In this work, the penetration of therapeutic agents of two distinct molecular weights into the spheroids of ovarian adenocarcinoma overexpressing human epidermal growth factor receptor 2 (HER2) was studied. It was shown that the low-molecular-weight chemotherapy drug, doxorubicin (~0.5 kDa), effectively penetrates through almost the entire depth of a 300 to 400 μm spheroid, while the penetration depth of the HER2-specific recombinant targeted toxin, DARPin-LoPE (~42 kDa), is only a few surface layers of cells and does not exceed 70 μm. The low penetration of the targeted toxin into spheroid was shown along with a significant decrease in its efficiency against the three-dimensional tumor spheroid as compared with the two-dimensional monolayer culture. The approaches to increasing the accumulation of agents in the tumor are presented and prospects of their use in order to improve the effectiveness of therapy are discussed.

Physical Properties of Fractions of GR-S and Their Vulcanizates

1949 ◽  
Vol 22 (2) ◽  
pp. 494-517 ◽  
Author(s):  
John A. Yanko
Keyword(s):  
Molecular Weight ◽  
Intrinsic Viscosity ◽  
Large Scale ◽  
Average Molecular Weight ◽  
Three Dimensional ◽  
Reduced Pressure ◽  
Molecular Weights ◽  
Styrene Copolymers ◽  
Straight Line ◽  
The Relationship

Abstract A large-scale precise fractionation of GR-S (X-55) was carried out at 25° C, using a fractional precipitation technique. Nine fractions, each weighing approximately 150 grams and comprising about 11 per cent by weight of the original unfractionated sample, were obtained, with number-average molecular weights varying from 4000 to 1,650,000. High molecular fractions undergo gelation rapidly, even when dried in the absence of light at reduced pressure, and the higher the molecular weight of the fraction, the greater the amount of gel formed. Compared to unfractionated butadiene-styrene copolymers of similar gel contents, the gel portions of the higher molecular fractions had unusually high swelling indices, indicating qualitatively that the average molecular weights between points of effective cross-linking in the three-dimensional gel structure were higher than those found in the past in unfractionated samples of similar gel contents. Through the concentration range studied, the intrinsic viscosity values varied as a straight-line function of the concentration terms for all the fractions. However, the negative slopes of these lines increased as the molecular weight of the fraction increased, demonstrating the greater dependence of the intrinsic viscosity values of the higher molecular fractions on the concentration variable. The relationship between number-average molecular weight, as determined by osmometric measurements, and limiting intrinsic viscosity of the GR-S fractions is given by the equation: [η]0=5.4×10−4 M0.66, which is similar to that obtained by French and Ewart. The μi values calculated from the equation of Huggins were essentially the same (0.35) through the molecular range 12,400 to 723,000.

Thermodynamic analysis on the binding of heavy metals onto extracellular polymeric substances (EPS) of activated sludge

2013 ◽  
Vol 47 (2) ◽  
pp. 607-614 ◽  
Author(s):  
Guo-Ping Sheng ◽  
Juan Xu ◽  
Hong-Wei Luo ◽  
Wen-Wei Li ◽  
Wei-Hua Li ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Activated Sludge ◽  
Thermodynamic Analysis ◽  
Extracellular Polymeric Substances

Effect of Initial Molecular Weight of a Rubber on the Strength and Fatigue of Its Vulcanizates

1957 ◽  
Vol 30 (1) ◽  
pp. 54-60
Author(s):  
G. M. Bartenev ◽  
A. S. Novikov ◽  
F. A. Galil-Ogly
Keyword(s):  
Molecular Weight ◽  
Dynamic Testing ◽  
Three Dimensional ◽  
Maximum Load ◽  
Testing Conditions ◽  
Maximum Deformation ◽  
Molecular Weights ◽  
Permanent Set ◽  
Dimensional Network ◽  
Equilibrium Modulus

Abstract (1) With decrease of the original molecular weight of rubber, there is a parallel decrease of the durability of its vulcanizates when they contain the same percentage of combined sulfur. On the other hand, this decrease of durability with decrease of the original molecular weight is only slight for vulcanizates having the same equilibrium modulus, i.e., the same density of crosslinks in the three-dimensional network. (2) In dynamic testing which involves repeated stretching, the durability depends on the testing conditions when the vulcanizates contain the same percentage of combined sulfur and at the same time when either the original molecular weight of the rubber is low or the equilibrium modulus is small. On the contrary, when the original molecular weight or the modulus is high, the durability does not depend on the testing conditions. When vulcanizates have the same equilibrium modulus, their durability depends on the original molecular weight. In this latter case the durability increases with increase of the molecular weight, independent of the testing conditions (given maximum load, given maximum deformation, etc.), and reaches a practically constant value at high molecular weights. (3) The fundamental influence of the original molecular weight on the strength and dynamic durability of vulcanizates containing the same percentage of combined sulfur is manifest in the retardation of the formation of a spatial network in low-molecular rubbers when vulcanized. With rubber of low original molecular weight, vulcanization leads to the formation of a thin space network and consequently a large number of molecular chain ends outside the network. For this reason, vulcanizates of low-molecular rubbers when tested are characterized by high permanent set.

Resist Materials and Nanolithography

1999 ◽  
Vol 584 ◽  
Author(s):  
Elizabeth A. Dobisz
Keyword(s):  
Molecular Weight ◽  
Metal Binding ◽  
Mechanical Stability ◽  
Diffusion Reaction ◽  
Naval Research ◽  
Molecular Weights ◽  
Assembled Monolayers ◽  
Order Of Magnitude ◽  
Post Exposure Bake ◽  
Chemically Amplified Resists

AbstractThe work focuses on lithographic processes and materials for sub-50 nm lithography. Lithographic results of polymethyl methacrylates of molecular weights of 50,000, 100,000, 496,000, and 950, 000 are compared. It was found that the molecular weight and developer concentration do not affect smallest linewidth, within experimental error. However, the molecular weight does affect the line-to-line resolution in dense gratings of 40–60 nm in contrast and developer induced swelling. 40 nm period gratings are shown. The work next examines the use of chemically amplified resists for nanofabrication, with a focus on SAL-601. Sub-50 nm lines are defined with latitude of an order of magnitude in dose and a factor of two in post exposure bake time. The results are modeled with a diffusion reaction kinetic model and an approach to optimize resolution and reproducibility is presented. Challenges to attaining the ultimate resolution and line-to-line resolution in polymeric resists include contrast, mechanical stability, swelling, and adhesion. Metal binding self assembled monolayers (SAMs) are presented a class of resists, that circumvent the latter three complications. Work at the Naval Research Laboratory on SAM resists is outlined.

Synergistic effect of PLA–PBAT–PLA tri-block copolymers with two molecular weights as compatibilizers on the mechanical and rheological properties of PLA/PBAT blends

RSC Advances ◽  
2015 ◽  
Vol 5 (90) ◽  
pp. 73842-73849 ◽  
Author(s):  
Zhiqiang Sun ◽  
Bao Zhang ◽  
Xinchao Bian ◽  
Lidong Feng ◽  
Han Zhang ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Block Copolymers ◽  
Synergistic Effect ◽  
Rheological Properties ◽  
Systematic Study ◽  
Synergistic Effects ◽  
Molecular Weights ◽  
Different Molecular Weight

Systematic study on the synergistic effects of different molecular-weight PLA–PBAT–PLA tri-block copolymers on the mechanical and rheological properties of PLA/PBAT blends.

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