Evaluation of nanofiltration for disinfection by-products control in drinking water treatment

2001 ◽  
Vol 1 (5-6) ◽  
pp. 233-243 ◽  
Author(s):  
M. Itoh ◽  
S. Kunikane ◽  
Y. Magara
Keyword(s):  
Molecular Weight ◽  
River Water ◽  
High Performance ◽  
Membrane Surface ◽  
Drinking Water Treatment ◽  
Apparent Molecular Weight ◽  
Distribution Patterns ◽  
Low Concentrations ◽  
Almost All ◽  
By Products

DBP control by nanofiltration was studied. Nine DBPs including THMs were selected as target compounds. Reagent DBPs and DBPs formed as a result of chlorination of NOM contained in river water, were applied to nanofiltration to examine DBPs removal. Humic acid was used to investigate DBP precursor control. Nanofiltration was conducted for about one day for each experiment using two 2-inch membrane modules. NF showed high performance for DBP precursor removal but little effect on the removal of DBPs themselves, especially THMs. In the experiment of DBP precursors removal, rejections were 98 to 100 percent for most of the DBPFPs. For NOM in river water, rejections of THMFPs were 96 to 99 percent. This shows nanofiltration is effective even at low concentrations of NOM. Nanofiltration can remove almost all organic substances with the apparent molecular weight of greater than 2,000 daltons. Molecular weight distribution patterns of the permeate were different depending on NF. THMs showed decreasing rejection as filtration proceeded because of adsorption on the membrane surface. THM rejections at 24 hours after filtration started were about 10 and 30 percent in Module-A and B, respectively. Haloacetic acids showed relatively higher rejections. It is recommended, from the viewpoint of THM control, that NOM removal using NF is much preferable to the removals of THM, formed by chlorination, using NF.

scholarly journals Impact of Simulated Human Gastrointestinal Digestion on the Bioactive Fraction of Upcycled Pineapple By-Products

Foods ◽  
2022 ◽  
Vol 11 (1) ◽  
pp. 126
Author(s):  
Ricardo Gómez-García ◽  
Ana A. Vilas-Boas ◽  
Ana Oliveira ◽  
Manuela Amorim ◽  
José A. Teixeira ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Performance ◽  
Antioxidant Activities ◽  
Liquid Fraction ◽  
Biological Activities ◽  
Soluble Carbohydrates ◽  
Small Molecular Weight ◽  
Carbohydrate Source ◽  
The Impact ◽  
By Products

Pineapple by-products (peels and stems) from fruit processing industries were evaluated to understand its potential application as a functional food. Therefore, the bioactive compounds of pineapple by-products were characterized for prebiotic and antioxidant activities. A total characterization of soluble carbohydrates profile (simples and complex carbohydrates), as well as polyphenols was performed, after removal of enzymatic fraction from pineapple crude juice, allowing the decrease of proteolytic activity and improving the other biological activities. Results showed that pineapple liquid fraction, from stem and peels, can be applied as a prebiotic enhancer, promoting the growth of five probiotic microorganisms (two strains of Lactobacillus sp. and three strains of Bifidobacterium sp.), as a single carbohydrate source. Moreover, through HPLC (High Performance Liquid Chromatography) analysis, 10 polyphenols were identified in pineapple liquid fractions, with some expected differences between both evaluated by-products. Gastrointestinal tract was simulated, in a continuous mode to understand the impact of pH changes and gastrointestinal enzymes into pineapple liquid fractions. Results showed a digestion of high molecular weight polysaccharides into small molecular weight tri-, di-, and monosaccharides. There was an increase of samples antioxidant activity through the gastrointestinal stage, followed by the release of specific polyphenols, such as chlorogenic, coumaric, and ferulic acids. The prebiotic activity did not improve throughout the simulation, in fact, the prebiotic potential decreased throughout the different stages.

scholarly journals The cercarial glycocalyx of Schistosoma mansoni.

1985 ◽  
Vol 100 (5) ◽  
pp. 1423-1434 ◽  
Author(s):  
J C Samuelson ◽  
J P Caulfield
Keyword(s):  
Electron Microscopy ◽  
Molecular Weight ◽  
Schistosoma Mansoni ◽  
High Molecular Weight ◽  
Membrane Surface ◽  
Periodate Oxidation ◽  
Apparent Molecular Weight ◽  
Ruthenium Red ◽  
Unit Membrane

Cercariae, the freshwater stage of Schistosoma mansoni infectious to man, are covered by a single unit membrane and an immunogenic glycocalyx. When cercariae penetrate the host skin, they transform to schistosomula by shedding tails, secreting mucous and enzymes, and forming microvilli over their surface. Here the loss of the glycocalyx from cercariae transforming in vitro was studied morphologically and biochemically. By scanning electron microscopy, the glycocalyx was a dense mesh composed of 15-30 nm fibrils that obscured spines on the cercarial surface. The glycocalyx was absent on organisms fixed without osmium and was partially lost when parasites aggregated in their own secretions before fixation. By transmission electron microscopy, a 1-2 microns thick mesh of 8-15-nm fibrils was seen on parasites incubated with anti-schistosomal antibodies or fixed in aldehydes containing tannic acid or ruthenium red. Cercariae transformed to schistosomula when tails were removed mechanically and parasites were incubated in saline. Within 5 min of transformation, organisms synchronously formed microvilli which elongated to 3-5 microns by 20 min and then were shed. However, considerable fibrillar material remained adherent to the double unit membrane surface of schistosomula. For biochemical labeling, parasites were treated with eserine sulfate, which blocked cercarial swimming, secretion, infectivity, and transformation to schistosomula. Material labeled by periodate oxidation and NaB3H4 was on the surface as shown by autoradiography and had an apparent molecular weight of greater than 10(6) by chromatography. Periodate-NaB3H4 glycocalyx had an isoelectric point of 5.0 +/- 0.4 and was precipitable with anti-schistosomal antibodies. More than 60% of the radiolabeled glycocalyx was released into the medium by transforming parasites in 3 h and was recovered as high molecular weight material. Parasites labeled with periodate and fluorescein-thiosemicarbazide and then transformed had a corona of fluorescence containing microvilli, much of which was shed onto the slide. Material on cercariae labeled by lodogen-catalyzed iodination was also of high molecular weight and was antigenic. In conclusion, the cercarial glycocalyx appears to be composed of acidic high molecular weight fibrils which are antigenic and incompletely cleared during transformation.

Molecular heterogeneity of the β-core fragment of human chorionic gonadotrophin

1993 ◽  
Vol 139 (3) ◽  
pp. 519-532 ◽  
Author(s):  
S. F. de Medeiros ◽  
F. Amato ◽  
C. D. Matthews ◽  
R. J. Norman
Keyword(s):  
Molecular Weight ◽  
High Performance ◽  
Apparent Molecular Weight ◽  
Chorionic Gonadotrophin ◽  
Human Chorionic Gonadotrophin ◽  
Molecular Heterogeneity ◽  
Hplc Separation ◽  
Con A ◽  
Peripheral Tissues ◽  
Core Fragment

ABSTRACT We have analysed the structure and composition of the β-core fragment of human chorionic gonadotrophin (βC-hCG) from fresh urine specimens obtained from pregnant women and compared our findings with those previously proposed by other groups using different protocols. SDS-PAGE separation of reduced βC-hCG demonstrated two major bands with apparent molecular weights of Mr 8900 and Mr 7500. The molecular weight of the agalacto βC-hCG was estimated to be Mr 10 218 from the amino acid analysis after high-performance liquid chromatography (HPLC) separation. Moreover, HPLC separation of its reduced and S-carboxymethylated peptides resulted in three peaks, but only two of them could be sequenced and demonstrated to be the previously reported β6-40 (Mr 5000) and β55-92 (Mr 5300) peptides of the βhCG subunit. The results showed that 56-78% of βC-hCG molecules of molecular weight Mr 12 800 were able to bind Concanavalin A (Con A). While most were lacking all the peripheral monosaccharides and terminated in mannose, some retained other sugar residues on their antennae. Direct carbohydrate analysis showed the following molar content normalized to six mannose molecules: galactose 2·8, glucosamine 5·3, galactosamine 0·3, fucose 1·7 and sialic acid 3·0. Approximately 22–44% of the βC-hCG molecules did not bind Con A (Con A non-reactive forms), of which 88% were totally deprived of sugar units and had an apparent molecular weight of approximately Mr 10 000, and 12% were weakly reactive to Con A and reactive to anion exchange (negatively charged forms), being incompletely trimmed of their oligosaccharide chains. Comparison of our results with those of two other groups have indicated that the differences noted among preparations are due to either the source or the methods used to purify and characterize this fragment. In addition, our results showed significant microheterogeneity on the N-linked oligosaccharide moieties with some molecules apparently having no sugar molecules. These results have implications for the origins of βC-hCG, suggesting secretion of some molecules without sugar chains and in other cases possible metabolism of hCG in the peripheral tissues. Journal of Endocrinology (1993) 139, 519–532

BEHAVIOUR OF OZONATION BY-PRODUCTS DURING ADVANCED DRINKING WATER TREATMENT WITH PEARL RIVER WATER

2018 ◽  
Vol 17 (5) ◽  
pp. 1035-1041
Author(s):  
Yue Wu ◽  
Chun-De Wu ◽  
Zhi-Lin Zhang ◽  
Fauzia Naluswata ◽  
Bo-Jie Yuan ◽  
...  
Keyword(s):  
Drinking Water ◽  
Water Treatment ◽  
River Water ◽  
Drinking Water Treatment ◽  
Pearl River ◽  
By Products ◽  
Advanced Drinking Water Treatment

Synthesis of new organic–inorganic hybrids poly[2-hydroxethyl methacrylate (HEMA)-glycidyl methacrylate (GMA)-silica] and their mechanical properties

2008 ◽  
Vol 23 (1) ◽  
pp. 66-71
Author(s):  
Shuxi Li ◽  
Solomon Praveen Samuel ◽  
Andreas Mylonakis ◽  
Apoorva Shah ◽  
Alex Hsieh ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Glycidyl Methacrylate ◽  
Sol Gel ◽  
Low Molecular Weight ◽  
Silica Hybrids ◽  
Almost All ◽  
Sol Gel Synthesis ◽  
And Storage ◽  
By Products

The presence of low-molecular-weight by-products is a major problem in poly[2-hydroxethyl methacrylate (HEMA)-silica] hybrids prepared using sol-gel synthesis. Low-molecular-weight by-products have a detrimental effect on the optical transparency, and mechanical and storage properties of poly(HEMA-silica) hybrids. To solve this problem, a new sol-gel synthesis procedure was developed to prepare organic–inorganic hybrids. Glycidyl methacrylate (GMA) was used as a comonomer to form poly(HEMA-GMA-silica) (PHGS) hybrids. In addition to forming a copolymer, GMA has two more functions. It facilitates the removal of almost all of the low-molecular-weight by-product molecules formed during sol-gel synthesis and also prevents further condensation of free silanol groups during the polymerization, storage, and use. The mechanical properties of PHGS hybrids were evaluated by using compression testing. The mechanical properties of PHGS hybrids were higher compared to Plexiglas G poly(methyl methacrylate), and the hybrids can be synthesized with reproducible mechanical properties.

Vacuum System to Minimize the Specimen Contamination of High-Performance EM

1977 ◽  
Vol 35 ◽  
pp. 68-69
Author(s):  
N. Yoshimura ◽  
K. Shirota ◽  
T. Etoh
Keyword(s):  
Electron Microscope ◽  
High Speed ◽  
High Performance ◽  
High Vacuum ◽  
Vacuum System ◽  
Pump System ◽  
Pumping System ◽  
Diffusion Pump ◽  
Almost All ◽  
Cascade Type

One of the most important requirements for a high-performance EM, especially an analytical EM using a fine beam probe, is to prevent specimen contamination by providing a clean high vacuum in the vicinity of the specimen. However, in almost all commercial EMs, the pressure in the vicinity of the specimen under observation is usually more than ten times higher than the pressure measured at the punping line. The EM column inevitably requires the use of greased Viton O-rings for fine movement, and specimens and films need to be exchanged frequently and several attachments may also be exchanged. For these reasons, a high speed pumping system, as well as a clean vacuum system, is now required. A newly developed electron microscope, the JEM-100CX features clean high vacuum in the vicinity of the specimen, realized by the use of a CASCADE type diffusion pump system which has been essentially improved over its predeces- sorD employed on the JEM-100C.

A high-performance oil-free backing pump for electron microscopes

1978 ◽  
Vol 36 (1) ◽  
pp. 110-111
Author(s):  
G.K.W. Balkau ◽  
E. Bez ◽  
J.L. Farrant
Keyword(s):  
Molecular Weight ◽  
Electron Microscope ◽  
Hot Spots ◽  
High Performance ◽  
Carbonaceous Material ◽  
Contamination Rate ◽  
Low Molecular Weight ◽  
Principal Source ◽  
Rotary Pumps ◽  
Electron Microscopes

The earliest account of the contamination of electron microscope specimens by the deposition of carbonaceous material during electron irradiation was published in 1947 by Watson who was then working in Canada. It was soon established that this carbonaceous material is formed from organic vapours, and it is now recognized that the principal source is the oil-sealed rotary pumps which provide the backing vacuum. It has been shown that the organic vapours consist of low molecular weight fragments of oil molecules which have been degraded at hot spots produced by friction between the vanes and the surfaces on which they slide. As satisfactory oil-free pumps are unavailable, it is standard electron microscope practice to reduce the partial pressure of organic vapours in the microscope in the vicinity of the specimen by using liquid-nitrogen cooled anti-contamination devices. Traps of this type are sufficient to reduce the contamination rate to about 0.1 Å per min, which is tolerable for many investigations.

Physico-Chemical Properties of Recombinant Desulphatohirudin

1990 ◽  
Vol 63 (03) ◽  
pp. 499-504 ◽  
Author(s):  
A Electricwala ◽  
L Irons ◽  
R Wait ◽  
R J G Carr ◽  
R J Ling ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Gel Filtration ◽  
Chemical Properties ◽  
Alpha Helix ◽  
Apparent Molecular Weight ◽  
Correlation Spectroscopy ◽  
Nmr Studies ◽  
Recombinant Hirudin ◽  
Physico Chemical ◽  
Recombinant Molecule

SummaryPhysico-chemical properties of recombinant desulphatohirudin expressed in yeast (CIBA GEIGY code No. CGP 39393) were reinvestigated. As previously reported for natural hirudin, the recombinant molecule exhibited abnormal behaviour by gel filtration with an apparent molecular weight greater than that based on the primary structure. However, molecular weight estimation by SDS gel electrophoresis, FAB-mass spectrometry and Photon Correlation Spectroscopy were in agreement with the theoretical molecular weight, with little suggestion of dimer or aggregate formation. Circular dichroism studies of the recombinant molecule show similar spectra at different pH values but are markedly different from that reported by Konno et al. (13) for a natural hirudin-variant. Our CD studies indicate the presence of about 60% beta sheet and the absence of alpha helix in the secondary structure of recombinant hirudin, in agreement with the conformation determined by NMR studies (17)

The Activation of Human Factor IX

1975 ◽  
Vol 33 (03) ◽  
pp. 553-563 ◽  
Author(s):  
B Østerud ◽  
K Laake ◽  
H Prydz
Keyword(s):  
Molecular Weight ◽  
Sodium Dodecyl ◽  
Apparent Molecular Weight ◽  
Factor Ix ◽  
Factor Vii ◽  
Activate Factor ◽  
Human Factor Ix ◽  
Factor Xia ◽  
Tissue Thromboplastin ◽  
Native Factor

SummaryThe activation of factor IX purified from human plasma has been studied. Factor XIa and kallikrein separately activated factor IX to factor IXa. In both cases factor IX a had an apparent molecular weight of about 42–45000 in sodium dodecyl sul-phate-polyacrylamide disc gel electrophoresis compared with a molecular weight of about 70000 for the native factor IX. The activation by XIa required Ca2+-ions whereas Ca2+-ions did not influence the activation by kallikrein. A mixture of tissue thromboplastin and factor VII or RusselPs-viper venom alone did not activate factor IX. Trypsin activated and plasmin inactivated factor IX.

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