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1

Regeneration of Cellulose Acetate Membranes.  

National Technical Information Service (NTIS)

Several simple methods for in situ one-step regeneration of both flux and salt-retention properties of service-deteriorated membranes have been developed. Membranes have been successfully regenerated using hot, 4% acetic acid, and a one-step cleaning meth...

P. A. Cantor W. S. Higley C. W. Saltonstall

1970-01-01

2

Fabricating PFPE Membranes for Capillary Electrophoresis  

NASA Technical Reports Server (NTRS)

A process has been developed for fabricating perfluoropolyether (PFPE) membranes that contain microscopic holes of precise sizes at precise locations. The membranes are to be incorporated into laboratory-on-a-chip microfluidic devices to be used in performing capillary electrophoresis. The present process is a modified version of part of the process, described in the immediately preceding article, that includes a step in which a liquid PFPE layer is cured into solid (membrane) form by use of ultraviolet light. In the present process, one exploits the fact that by masking some locations to prevent exposure to ultraviolet light, one can prevent curing of the PFPE in those locations. The uncured PFPE can be washed away from those locations in the subsequent release and cleaning steps. Thus, holes are formed in the membrane in those locations. The most straightforward way to implement the modification is to use, during the ultraviolet-curing step, an ultraviolet photomask similar to the photomasks used in fabricating microelectronic devices. In lieu of such a photomask, one could use a mask made of any patternable ultraviolet-absorbing material (for example, an ink or a photoresist).

Lee, Michael C.; Willis, Peter A.; Greer, Frank; Rolland, Jason

2009-01-01

3

Isolation of membrane protein complexes by blue native electrophoresis.  

PubMed

Blue native PAGE is a discontinuous electrophoretic system that allows the separation of membrane protein complexes in a native, enzymatically active state with high resolution. Membrane protein complexes are solubilized by neutral, nondenaturing detergents like n-dodecyl-beta-D-maltoside. After addition of Coomassie G250 that binds to the surface of the proteins, separation of the negatively charged complexes according to molecular mass is possible. After electrophoresis the structure and function of the isolated protein complexes can be investigated. PMID:18369880

Reisinger, Veronika; Eichacker, Lutz A

2008-01-01

4

Isolation of Spiroplasma citri membranes and characterization of membrane proteins by two-dimensional gel electrophoresis  

Microsoft Academic Search

This paper describes a method for isolating plasma membranes fromSpiroplasma citri and for comparing membrane and cytoplasmic proteins by two-dimensional gel electrophoresis. Plasma membranes ofS. citri were stabilized against fragmentation by coating cell with Concanavalin A just prior to lysis. After lysis of the cells by ultrasonic irradiation, membranes were purified by differential centrifugation and step gradients. The purified fraction,

Philippe Simoneau; Jacques Labarère

1988-01-01

5

Photoelectrochemistry of polyaniline supported in a microporous cellulose acetate membrane  

Microsoft Academic Search

We studied the photoelectrochemical response of polyaniline dispersed in a microporous membrane structure. Films of the composite were obtained by electropolymerization of aniline on a platinum electrode coated with a microporous cellulose acetate membrane. They were characterized by UV—Visible spectroscopy, scanning electron microscopy and electrochemical impedance spectroscopy. We compared the results with a electrochemically synthesized polyaniline and a composite film

S. das Neves; M.-A. De Paoli

1998-01-01

6

Cellulose Acetate Decoupler for On-Column Electrochemical Detection in Capillary Electrophoresis  

PubMed Central

A new decoupler for on-column electrochemical detection in capillary electrophoresis is presented. The decoupler is constructed by etching a series of holes through the side of the separation capillary with a CO2 laser and then coating the holes with cellulose acetate. The decoupler shows isolation of the detection circuit for separation currents up to 30 ?A. Detection limits below 1 nM were achieved for four model compounds, including anions, neutrals, and cations, using the laser-etched decoupler. This decoupler design combines excellent mechanical stability, effective shunting of high separation currents, and ease of manufacture.

Osbourn, Damon M.; Lunte, Craig E.

2008-01-01

7

Cellulose acetate decoupler for on-column electrochemical detection in capillary electrophoresis.  

PubMed

A new decoupler for on-column electrochemical detection in capillary electrophoresis is presented. The decoupler is constructed by etching a series of holes through the side of the separation capillary with a CO2 laser and then coating the holes with cellulose acetate. The decoupler shows isolation of the detection circuit for separation currents up to 30 microA. Detection limits below 1 nM were achieved for four model compounds, including anions, neutrals, and cations, using the laser-etched decoupler. This decoupler design combines excellent mechanical stability, effective shunting of high separation currents, and ease of manufacture. PMID:11791566

Osboum, D M; Lunte, C E

2001-12-15

8

Cellulose acetate nanofiltration hollow fiber membranes for forward osmosis processes  

Microsoft Academic Search

Cellulose acetate (CA) nanofiltration (NF) hollow fiber membranes have been fabricated and tested in the forward osmosis (FO) process. A two-step heat-treatment, i.e., 60min at 60°C and 20min at 95°C, effectively shrinks the membrane mean pore radius from 0.63 to 0.30nm. The molecular weight cut off (MWCO) of the resultant CA NF membrane is 186Da. In the NF experiments under

Jincai Su; Qian Yang; Joo Fuat Teo; Tai-Shung Chung

2010-01-01

9

Pervaporation characteristics of ethylene–vinyl acetate copolymer membranes with different composition for recovery of ethyl acetate from aqueous solution  

Microsoft Academic Search

The degree of crystallization, surface property and density of ethylene–vinyl acetate (EVA) copolymer membranes with different vinyl acetate (VA) content were measured by differential scanning calorimetry (DSC), contact angle meter and pycnometer. The pervaporation (PV) characteristics of the EVA copolymer membranes for recovery of ethyl acetate (EA) from aqueous EA solutions have been investigated. The separation factor (?) decreased with

Yunxiang Bai; Jinwen Qian; Quanfu An; Zhihui Zhu; Peng Zhang

2007-01-01

10

Solubilization of membrane proteins for two-dimensional gel electrophoresis: identification of sarcoplasmic reticulum membrane proteins.  

PubMed

Solubilization of membrane proteins for two-dimensional electrophoresis (2DE) is very difficult. In this study, we report the use of 1,2-diheptanoyl-sn-glycero-3-phosphatdiyl choline (DHPC) as a detergent to solubilize integral membrane proteins for 2DE. Rat ventricular microsomal fractions enriched with sarco(endo)plasmic reticulum (SR) membrane proteins were used as a model system. Compatibility of DHPC with a high concentration of urea increases the solubility of proteins compared with sulphobetaines or ASB-14. Peptide mass analysis assisted in the identification of key SR membrane proteins including SR Ca(2+) ATPase and other membrane proteins, which have not previously been reported on 2DE. These results suggest that DHPC is a better detergent for solubilizing membrane proteins and may be useful in generating proteomic maps for most complex organelles including SR. PMID:14715292

Babu, Gopal J; Wheeler, Debra; Alzate, Oscar; Periasamy, Muthu

2004-02-01

11

Ion selective permeation through cellulose acetate membranes in forward osmosis.  

PubMed

Solute-solute interactions can have a dramatic impact on the permeation of solutes through dense polymeric membranes. In particular, understanding how solute-solute interactions can affect the design of osmotically driven membrane processes (ODMPs) is critical to the successful development of these emerging water treatment and energy generation processes. In this work, we investigate the influence that solute-solute interactions have on nitrate permeation through an asymmetric cellulose acetate forward osmosis membrane. A series of experiments that included systematic modifications to the cation paired with nitrate, the identity of the draw solute, and the solution pH were conducted. These experiments reveal that in the unique operating geometry of ODMPs, where solute containing solutions are present on both sides of the membrane, nitrate fluxes are significantly higher (>15 times in some cases) than predicted by existing models for solute permeation in ODMPs. The identity of the cation paired with nitrate influences the flux of nitrate; the identity of the cation in the draw solution does not affect the flux of nitrate; however, the identity of the anion in the draw solution has the most significant impact on the flux of nitrate. These results suggest that an ion exchange mechanism, which allows nitrate to switch rapidly with anions from the draw solution, is present when cellulose acetate based membranes are used in ODMPs. PMID:24152190

Irvine, Gavin J; Rajesh, Sahadevan; Georgiadis, Michael; Phillip, William A

2013-12-01

12

Cellulose membranes for reverse osmosis Part I. RO cellulose acetate membranes including a composite with polypropylene  

Microsoft Academic Search

With the aim of obtaining RO membranes for brackish water desalination from purified celluloses (cotton linters and bleached bagasse pulp), two reactions (heterogeneous and homogeneous) were applied for the synthesis of cellulose acetate (CA). The efficiency of the membranes was measured and compared with those prepared from purchased CA and prepared CA by acetylation of imported high-grade viscose wood pulp.

Houssni El-Saied; Altaf H. Basta; Barsoum N. Barsoum; Mohamed M. Elberry

2003-01-01

13

Transport Parameters in a Porous Cellulose Acetate Membrane  

PubMed Central

The transport parameters of a cellulose acetate membrane prepared from a mixture of cellulose acetate, formamide, and acetone, 25:25:50 by weight, were studied. The membrane consists of a thin, porous layer, the skin, in series with a thick, highly porous layer, the coarse support. In the skin the diffusional permeability coefficient, ?, of a number of small amides and alcohols depends critically upon the partition coefficient, Ks, the size of the molecule, and the apparent hydrogen-bonding ability, Ns, of the solute. These observations are in general agreement with our earlier conclusions on the properties of nonporous membranes. On the other hand, the corrected reflection coefficient, ?', is not a very sensitive function of either Ns or Ks taken separately. The correlation between ?' and molecular diameter is reasonably good; however, it is much improved when both Ns and Ks are taken into consideration. Isotope interaction was also studied in the present preparation and was found to provide only a small (5–8%) contribution to the diffusional permeability coefficient of ethylene glycol. The contribution of solute-water friction was found to be less than 24% of the total solute friction.

DiPolo, R.; Sha'afi, R. I.; Solomon, A. K.

1970-01-01

14

The Effects of Porous and Solid Fillers on the Permeability of Cellulose Acetate Membranes.  

National Technical Information Service (NTIS)

Several types of filled cellulose acetate membranes were prepared to determine the effect of filler properties and polymer properties on permeability of the composite materials. Casting procedures were chosen to give a dense cellulose acetate phase and a ...

P. Harriott J. Wu F. Klunker

1973-01-01

15

Pervaporation of acetic acid\\/water mixtures through carbon molecular sieve-filled PDMS membranes  

Microsoft Academic Search

The pervaporation process for acetic\\/water has been investigated with carbon molecular sieve (CMS)-filled polydimethylsiloxane (PDMS) membranes. The effects of feed temperature, feed acetic acid concentration and CMS content on the performance of the membranes have been studied. It is found that the addition of CMS can improve pervaporation behavior of PDMS membranes to some extent and greatly increases the strength

Lei Li; Zeyi Xiao; Zhibing Zhang; Shujuan Tan

2004-01-01

16

Towards green membranes: preparation of cellulose acetate ultrafiltration membranes using methyl lactate as a biosolvent  

Microsoft Academic Search

Ultrafiltration membranes were prepared using cellulose acetate (CA) as a polymer, LiCl and CaCl2 as porogens and methyl-(S)-lactate as a solvent. CA, methyl lactate and the porogens used in this work are obtained from renewable resources; they are biodegradable, non-toxic and non-volatile organic compounds. Flat sheet ultrafiltration membranes were prepared by the phase inversion technique. A molecular weight cut-off between

Y. Medina-Gonzalez; P. Aimar; J.-F. Lahitte; J.-C. Remigy

2011-01-01

17

Application of cellulose acetate butyrate-based membrane for osmotic drug delivery  

Microsoft Academic Search

The release rate of drugs from an OROS is controlled by semipermeable membranes composed typically of cellulose acetate (CA) with various flux enhancers. Cellulose\\u000a acetate butyrate (CAB) was identified as a viable alternative. The CAB membrane matched the CA membrane in robustness but\\u000a had superior drying properties, offering particular advantages for thermolabile formulations. Studies were conducted to characterize\\u000a CAB membrane

Anant Shanbhag; Brian Barclay; Joanna Koziara; Padmaja Shivanand

2007-01-01

18

Study on cellulose acetate membranes for reverse osmosis and polyethersulfone membranes for ultrafiltration by electron spin resonance technique  

Microsoft Academic Search

Electron spin resonance (ESR) technique was used to study cellulose acetate (CA) membranes for reverse osmosis (RO) and polyethersulfone (PES) membranes for ultrafiltration. TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy — free radical) was used as a spin probe that was brought into the membranes by immersing the membranes into solutions involving TEMPO, or by blending TEMPO into membrane casting solutions. It was found that

K. C. Khulbe; T. Matsuura; C. Y. Feng

2002-01-01

19

Role of membrane surface morphology in colloidal fouling of cellulose acetate and composite aromatic polyamide reverse osmosis membranes  

Microsoft Academic Search

Laboratory-scale colloidal fouling tests, comparing the fouling behavior of cellulose acetate and aromatic polyamide thin-film composite reverse osmosis (RO) membranes, are reported. Fouling of both membranes was studied at identical initial permeation rates so that the effect of the transverse hydrodynamic force (permeation drag) on the fouling of both membranes is comparable. Results showed a significantly higher fouling rate for

Menachem Elimelech; Xiaohua Zhu; Amy E. Childress; Seungkwan Hong

1997-01-01

20

Water and ions transport mechanism in hyperfiltration with symmetric cellulose acetate membranes  

Microsoft Academic Search

Hyperfiltration is carried out under reverse osmotic conditions by the application of mechanical energy to force the solvent from higher to lower concentration of solute across semipermeable membranes. In the present investigation, experimental work has been performed to measure the water and inorganic cation transport fluxes across cellulose acetate homogeneous hyperfiltration membranes. The osmosis, reverse osmosis, kinetic conductance and membrane

M. Ashraf Chaudry

2002-01-01

21

In Situ Formation of Cellulose Acetate Carbamate Dry-RO (Trade Name) Membranes.  

National Technical Information Service (NTIS)

The in situ formation of cellulose acetate (CA) carbamates was investigated to increase the performance of Dry-RO membranes of CA. The CA casting solutions were charged with reversibly blocked isocyanate monomers, which when heated, formed CA carbamates. ...

R. E. Kesting J. Ditter A. Murray J. Newman

1980-01-01

22

Gas permeation properties of ethylene vinyl acetate–silica nanocomposite membranes  

Microsoft Academic Search

The effect of silica nanoparticles on the gas separation properties of ethylene vinyl acetate (EVA) copolymer containing 28% vinyl acetate has been investigated. The EVA and hybrid EVA–silica membranes were prepared via thermal phase inversion method. Silica nanoparticles prepared by hydrolysis of tetraethylorthosilicate (TEOS), through the sol–gel mechanism. The prepared membranes were characterized using FT-IR, SEM, DSC and XRD methods.

Morteza Sadeghi; Ghader Khanbabaei; Amir H. Saeedi Dehaghani; Mohammad Sadeghi; Mohammad A. Aravand; Mohammad Akbarzade; Somaieh Khatti

2008-01-01

23

Demystifying Hardy-Weinberg: Using Cellulose Acetate Electrophoresis of the Lap Locus to Study Population Genetics in White Campion (Silene latifolia)  

NSDL National Science Digital Library

This laboratory exercise could used as an introductory biology lab and/or an upper level course lab, with minor adjustments, covering ecology, evolution, population genetics and physiology. Population genetics is explored using seedlings from several population of the perennial herb white campion, (Silene latifolia), scientific method,cellulose acetate protein electrophoresis and the Hardy-Weinberg Equilibrium Theory.

Patricia A. Peroni (Davidson College;); David E. McCauley (Vanderbilt University;)

1999-01-01

24

Electrophoresis of concanavalin A receptors along embryonic muscle cell membrane  

Microsoft Academic Search

Fluorescent concanavalin A (con A)-labelling showed that an electric field of 4 V cm-1 grossly redistributed con A receptors along the plasma membranes of living muscle cells within 4 h. This field produced a voltage drop of 12 mV across these 30 µm-wide cells. The movement of receptors was independent of cell metabolism and seemed to be electrophoretic in nature.

Mu-Ming Poo; Kenneth R. Robinson

1977-01-01

25

Nafion membrane electrophoresis with direct and simplified end-column pulse electrochemical detection of amino acids.  

PubMed

A novel electrophoresis technique, in which the separation column was replaced by a strip of Nafion membrane (5.0 cm x 0.20 mm x 0.25 mm), was developed for the separation of an amino acid mixture (glycine, asparic acid and lysine), followed by quadruple-pulse electrochemical detection. Nafion membrane contains hydrophilic pores (10-20 A and 50-60 A in size) acting as very narrow electrophoresis channels. The fixed-charge sites (-SO(3) (-)) on the hydrophilic pore surface provide a strong charged background. A platinum disk electrode (0.90 mm inner diameter) was employed as the detection electrode and the electrophoresis cathode was used as the quasi-reference and counter electrode for the end-column electrochemical detector, without decoupler. Under optimized conditions the mixture of amino acids could be separated at a voltage of only 90 V with a detection limit of 10(-7) M, indicating that Nafion membrane electrophoresis is a potentially attractive technique for the separation of small organic molecules or ions. PMID:14743490

Fang, Cheng; Wu, Bingliang; Zhou, Xingyao

2004-01-01

26

Inability of Microorganisms To Degrade Cellulose Acetate Reverse-Osmosis Membranes  

PubMed Central

Operational cellulose acetate reverse-osmosis membranes were examined for evidence of biological degradation. Numerous fungi and bacteria were isolated by direct and enrichment techniques. When tested, most of the fungi were active cellulose degraders, but none of the bacteria were. Neither fungi nor bacteria were able to degrade cellulose acetate membrane in vitro, although many fungi were able to degrade cellulose acetate membrane after it had been deacetylated. Organisms did not significantly degrade powdered cellulose acetate in pure or mixed cultures as measured by reduction in acetyl content or intrinsic viscosity or production of reducing sugars. Organisms did not affect the performance of cellulose triacetate fibers when incubated with them. The inability of the organisms to degrade cellulose acetate was attributed to the high degree of acetate substitution of the cellulose polymer. The rate of salt rejection decline was strongly correlated with chlorination of feed water and inversely with densities of microorganisms. These data suggest that microbial degradation of operational cellulose acetate reverse-osmosis membranes is unlikely.

Ho, Leighton C. W.; Martin, David D.; Lindemann, William C.

1983-01-01

27

Proteoliposome-based capillary electrophoresis for screening membrane protein inhibitors.  

PubMed

A method for screening of monoamine oxidase (MAO) inhibitor was carried out using capillary electrophoresis (CE) based on the interaction of MAO and its substrate kynuramine (Kyn). Bioactive proteoliposome was reconstituted by liposome and MAO and then was applied as the pseudostationary phase (PSP) of CE to mimic the interaction between the enzyme and its substrate. N-prolmrgyl-R-2-heptylamine (R-2-HPA) and rasagiline [N-propargyl-1-(R)-aminoindan], which are two kinds of MAO inhibitors, were added into the running buffers containing proteoliposome. The results showed that the relative migration time ratio (RMTR × 10(-1)) values of Kyn were enhanced from 8.88 to 9.31 with an increase of the concentrations of rasagiline from 10(-6) to 1 mM. However, the RMTR values of Kyn were enhanced from 8.83 to 9.14 with an increase of the concentrations of R-2-HPA from 10(-6) to 1 mM. The RMTR value of Kyn in the presence of rasagiline was larger than that in the presence of R-2-HPA when rasagiline and R-2-HPA were at the same concentration. The results indicated that the interaction between Kyn and MAO was weakened with the increase of the inhibitors. In addition, the results of offline incubation showed that the inhibitions of rasagiline were 100.0, 72.1, 51.8 and 5.4% at the concentration of 1, 10(-2), 10(-4) and 10(-6) mM; moreover, the inhibitions of R-2-HPA were 70.0, 44.9, 4.1 and 0.9% at the concentrations of 1, 10(-2), 10(-4) and 10(-6) mM. The inhibition efficiency of rasagiline was stronger than that of R-2-HPA at the same concentration. Additionally, the interaction between Kyn and liposome was also investigated. This newly developed method might provide a potential tool for screening MAO inhibitor. PMID:22547660

Li, Bing; Lv, Xuefei; Geng, Lina; Qing, Hong; Deng, Yulin

2012-08-01

28

[Computer-assisted findings on protein electrophoresis on cellulose acetate film].  

PubMed

Until a short time ago efficient computer assisted reporting of electrophoretograms was not possible owing to the lack of appropriate technology. By integrating a fully mechanized electrophoresis system into the laboratory data processing system of a centralized institute of clinical chemistry, the separation and the interpretation of results can be performed for 300 samples per day. The interpretation is based upon available patient data (specified clinical diagnoses, previous results), calculated fractions and analysis of the electrophoretic curve in the area of albumin and the beta- and gamma-globulin fraction. In this way it is possible to classify hereditary bisalbuminaemias and to detect transient bisalbuminaemias and monoclonal gammopathies. Diagnostic indications of specific dysproteinaemias and defect proteinaemias are printed on the report form if individual serum protein fractions and the total protein content are changed specifically. The results of the different electrophoretic fractions, the total protein and a set of possible alterations of the curve are numerically coded according to the scaled biochemical ranges in five definite sections or to a decision matrix (alteration 'given' or 'not given'), respectively. The composed 'result patterns' are matched with preassigned 'reference patterns' stored in the computer file. The procedure is efficient and adaptable to other areas of analysis. PMID:6207264

Knüppel, W; Neumeier, D; Fateh-Moghadam, A; Knedel, M

1984-06-01

29

Enhanced detergent extraction for analysis of membrane proteomes by two-dimensional gel electrophoresis  

PubMed Central

Background The analysis of hydrophobic membrane proteins by two-dimensional gel electrophoresis has long been hampered by the concept of inherent difficulty due to solubility issues. We have optimized extraction protocols by varying the detergent composition of the solubilization buffer with a variety of commercially available non-ionic and zwitterionic detergents and detergent-like phospholipids. Results After initial analyses by one-dimensional SDS-PAGE, quantitative two-dimensional analyses of human erythrocyte membranes, mouse liver membranes, and mouse brain membranes, extracted with buffers that included the zwitterionic detergent MEGA 10 (decanoyl-N-methylglucamide) and the zwitterionic lipid LPC (1-lauroyl lysophosphatidylcholine), showed selective improvement over extraction with the common 2-DE detergent CHAPS (3 [(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate). Mixtures of the three detergents showed additive improvements in spot number, density, and resolution. Substantial improvements in the analysis of a brain membrane proteome were observed. Conclusion This study demonstrates that an optimized detergent mix, coupled with rigorous sample handling and electrophoretic protocols, enables simple and effective analysis of membrane proteomes using two-dimensional electrophoresis.

Churchward, Matthew A; Butt, R Hussain; Lang, John C; Hsu, Kimberly K; Coorssen, Jens R

2005-01-01

30

An ATR-FTIR study of water in cellulose acetate membranes prepared by phase inversion  

Microsoft Academic Search

The state of water in the active layer of a series of cellulose acetate asymmetric membranes, prepared by the phase inversion process, was investigated using attenuated total reflection infrared spectroscopy (ATR-FTIR). The relative amount of water present in the active layer depends on the inherent surface or skin layer morphology; the more permeable ultrafiltration asymmetric membranes contain more water compared

Damien Murphy; Maria Norberta de Pinho

1995-01-01

31

Separation of nutmeg essential oil and dense CO 2 with a cellulose acetate reverse osmosis membrane  

Microsoft Academic Search

The association of membrane separation processes to the supercritical fluid extraction of essential oils from vegetable matrices can be an alternative to the reduction of recompression costs derived from the depressurization step necessary for the recovering of the extracts. In this work, a cellulose acetate reverse osmosis membrane was applied to perform the separation of nutmeg essential oil and dense

Cinthia Bittencourt Spricigo; Ariovaldo Bolzan; Ricardo Antonio Francisco Machado; Luiz Henrique Castelan Carlson; José Carlos Cunha Petrus

2001-01-01

32

Direct coupling of supported liquid membranes to capillary electrophoresis for analysis of complex samples: a tutorial.  

PubMed

This tutorial provides an overview of direct coupling of extraction techniques based on supported liquid membranes (SLMs) to capillary electrophoresis (CE) for treatment and subsequent analysis of complex samples. Pros and cons of using each of the described instrumental arrangement are addressed and where relevant, comments with personal experience of the authors are presented. Solid porous membrane based extraction techniques coupled directly to CE are also presented in this tutorial and a comprehensive discussion is included on their instrumental set-ups and their possible adaptation for use with SLMs. PMID:23830417

Kubá?, Pavel; Bo?ek, Petr

2013-07-17

33

Electrospun membrane of cellulose acetate for heavy metal ion adsorption in water treatment  

Microsoft Academic Search

Cellulose acetate (CA) nonwoven membrane for heavy metal ion adsorption was prepared by electrospinning and surface modification with poly(methacrylic acid) (PMAA). The morphology and graft modification of the membrane were characterized by SEM and ATR-FTIR. The adsorption of heavy metal ions Cu2+, Hg2+ and Cd2+ on this membrane was investigated. The adsorption capacity increased with the increasing of initial pH

Ye Tian; Min Wu; Ruigang Liu; Yanxiang Li; Deqian Wang; Junjun Tan; Rongcheng Wu; Yong Huang

2011-01-01

34

Adsorptive Membranes vs. Resins for Acetic Acid Removal from Biomass Hydrolysates  

SciTech Connect

Acetic acid is a compound commonly found in hemicellulosic hydrolysates. This weak acid strongly influences the bioconversion of sugar containing hydrolysates. Previous investigators have used anion exchange resins for acetic acid removal from different hemicellulosic hydrolysates. In this study, the efficiency of an anion exchange membrane was compared to that of an anion exchange resin, for acetic acid removal from a DI water solution and an acidic hemicellulose hydrolysate pretreated using two different methods. Ion exchange membranes and resins have very different geometries. Here the performance of membranes and resins is compared using two dimensionless parameters, the relative mass throughput and chromatographic bed number. The relative mass throughput arises naturally from the Thomas solution for ion exchange. The results show that the membrane exhibit better performance in terms of capacity, and loss of the desired sugars. In addition acetic acid may be eluted at a higher concentration from the membrane thus leading to the possibility of recovery and re-use of the acetic acid.

Han, B.; Carvalho, W.; Canilha, L.; da Silva, S. S.; e Silva, J. B. A.; McMillan, J. D.; Wickramasinghe, S. R.

2006-01-01

35

Integration of nanoporous membranes for sample filtration/preconcentration in microchip electrophoresis.  

PubMed

Microfluidic devices integrating membrane-based sample preparation with electrophoretic separation are demonstrated. These multilayer devices consist of 10 nm pore diameter membranes sandwiched between two layers of PDMS substrates with embedded microchannels. Because of the membrane isolation, material exchange between two fluidic layers can be precisely controlled by applied voltages. More importantly, since only small molecules can pass through the nanopores, the integrated membrane can serve as a filter or a concentrator prior to microchip electrophoresis under different design and operation modes. As a filter, they can be used for separation and selective injection of small analytes from sample matrix. This has been effectively applied in rapid determination of reduced glutathione in human plasma and red blood cells without any off-chip deproteinization procedure. Alternatively, in the concentrator mode, they can be used for online purification and preconcentration of macromolecules, which was illustrated by removing primers and preconcentrating the product DNA from a PCR product mixture. PMID:17117457

Long, Zhicheng; Liu, Dayu; Ye, Nannan; Qin, Jianhua; Lin, Bingcheng

2006-12-01

36

Simultaneous measurement of individual mitochondrial membrane potential and electrophoretic mobility by capillary electrophoresis.  

PubMed

Mitochondrial membrane potential varies, depending on energy demand, subcellular location, and morphology and is commonly used as an indicator of mitochondrial functional status. Electrophoretic mobility is a heterogeneous surface property reflective of mitochondrial surface composition and morphology, which could be used as a basis for separation of mitochondrial subpopulations. Since these properties are heterogeneous, methods for their characterization in individual mitochondria are needed to better design and understand electrophoretic separations of subpopulations of mitochondria. Here we report on the first method for simultaneous determination of individual mitochondrial membrane potential and electrophoretic mobility by capillary electrophoresis with laser-induced fluorescence detection (CE-LIF). Mitochondria were isolated from cultured cells, mouse muscle, or liver, and then polarized, labeled with JC-1 (a ratiometric fluorescent probe, which indicates changes in membrane potential), and separated with CE-LIF. Red/green fluorescence intensity ratios from individual mitochondria were used as an indicator of mitochondrial membrane potential. Reproducible distributions of individual mitochondrial membrane potential and electrophoretic mobility were observed. Analysis of polarized and depolarized regions of interest defined using red/green ratios and runs of depolarized controls allowed for the determination of membrane potential and comparison of electrophoretic mobility distributions in preparations containing depolarized mitochondria. Through comparison of these regions of interest, we observed dependence of electrophoretic mobility on membrane potential, with polarized regions of interest displaying decreased electrophoretic mobility. This method could be applied to investigate mitochondrial heterogeneity in aging or disease models where membrane potential is an important factor. PMID:24673334

Wolken, Gregory G; Arriaga, Edgar A

2014-05-01

37

Determination of Ca, K, Mg, Na, sulfate, phosphate, formate, acetate, propionate, and glycerol in biodiesel by capillary electrophoresis with capacitively coupled contactless conductivity detection  

Microsoft Academic Search

In this work, a new method employing capillary electrophoresis (CE) for the determination of several species in biodiesel is introduced. The concentrations of inorganic species (Na+, K+, Ca2+, Mg2+, SO42?, and PO43?) and glycerol are of interest to the regulatory authorities due to their ability to form undesirable compounds in engines. Additionally, other species of low molecular weight (e.g., acetate,

Thiago Nogueira; Claudimir Lucio do Lago

2011-01-01

38

Performances of poly(vinylpyrrolidone-co-vinyl acetate)-cellulose acetate blend membranes in the pervaporation of ethanol–ethyl tert-butyl ether mixtures  

Microsoft Academic Search

High performance pervaporation membranes for the selective removal of ethanol from ethyl t-butyl ether (ETBE) were prepared by blending cellulose acetate with poly(vinylpyrrolidone-co-vinyl acetate) in different proportions and studied in sorption and pervaporation of ethanol–ETBE mixtures of compositions ranging from 5 to 25wt% ethanol. The membrane performances are improved when the copolymer content is higher due to strong flux enhancement.

Quang-Trong Nguyen; Robert Clément; Irwan Noezar; Pierre Lochon

1998-01-01

39

Enhanced separation of membranes during free flow zonal electrophoresis in plants.  

PubMed

Free flow zonal electrophoresis (FFZE) is a versatile technique that allows for the separation of cells, organelles, membranes, and proteins based on net surface charge during laminar flow through a thin aqueous layer. We have been optimizing the FFZE technique to enhance separation of plant vacuolar membranes (tonoplast) from other endomembranes to pursue a directed proteomics approach to identify novel tonoplast transporters. Addition of ATP to a mixture of endomembranes selectively enhanced electrophoretic mobility of acidic vesicular compartments during FFZE toward the positive electrode. This has been attributed to activation of the V-ATPase generating a more negative membrane potential outside the vesicles, resulting in enhanced migration of acidic vesicles, including tonoplast, to the anode (Morré, D. J.; Lawrence, J.; Safranski, K.; Hammond, T.; Morré, D. M. J. Chromatogr., A 1994, 668, 201-213). We confirm that ATP does induce a redistribution of membranes during FFZE of microsomal membranes isolated from several plant species, including Arabidopsis thaliana, Thellungiella halophila, Mesembryanthemum crystallinum, and Ananas comosus. However, we demonstrate, using V-ATPase-specific inhibitors, nonhydrolyzable ATP analogs, and ionophores to dissipate membrane potential, that the ATP-dependent migrational shift of membranes under FFZE is not due to activation of the V-ATPase. Addition of EDTA to chelate Mg2+, leading to the production of the tetravalent anionic form of ATP, resulted in a further enhancement of membrane migration toward the anode, and manipulation of cell surface charge by addition of polycations also influenced the ATP-dependent migration of membranes. We propose that ATP enhances the mobility of endomembranes by screening positive surface charges on the membrane surface. PMID:17566980

Barkla, Bronwyn J; Vera-Estrella, Rosario; Pantoja, Omar

2007-07-15

40

Permeation performance of Cellulose acetate propionate\\/polyvinylidine fluoride blend membranes by phase inversion  

Microsoft Academic Search

In this study, cellulose acetate propionate (CAP) and polyvinylidene fluoride (PVDF) were selected to prepare porous-blend membrane by wet phase inversion method. The effect of the CAP and PVDF concentration of the casting solution on membrane morphology structure and thermal stability was investigated by scanning electron microscopy (SEM) and thermal gravimetry\\/differential scanning calorimetry (TGA\\/DSC). The pure water flux by the

Kuo-Liang Chuang; Ming-Chi Hsieh; Yun-Chieh Su; Hui-Hsin Tseng; Li-Luen Huang

2010-01-01

41

Polyethersulfone (PES)\\/cellulose acetate phthalate (CAP) blend ultrafiltration membranes: Preparation, morphology, performance and antifouling properties  

Microsoft Academic Search

Polyethersulfone (PES)\\/cellulose acetate phthalate (CAP) blend ultrafiltration (UF) membranes were prepared with phase inversion induced by immersion precipitation method. CAP was employed to improve the hydrophilicity of PES membranes. Polyvinylpyrrolidone (PVP) was selected as pore former. Dimethylacetamide (DMAc) and water+isopropyl alcohol (IPA) (80\\/20vol%) were used as solvent and coagulant respectively. The contact angle measurements indicate that the hydrophilicities of PES\\/CAP

A. Rahimpour; S. S. Madaeni

2007-01-01

42

Performance of cellulose acetate butyrate membranes in hyperfiltration of sodium chloride and urea feed solution  

NASA Technical Reports Server (NTRS)

Cellulose acetate butyrate (CAB) membranes are shown to give high salt and urea rejection with water flux of about 3 gallons/sq ft per day at 600 psig. Membranes prepared from a formulation containing glyoxal show a significant increase in flux and decrease in salt and urea rejection with drying time. Zero drying time gives maximum urea and salt rejection and is therefore most suitable for hyperfiltration of sodium chloride and urea feed solution.

Wydeven, T.; Leban, M.

1973-01-01

43

Controlled release of triprolidine using ethylene-vinyl acetate membrane and matrix systems.  

PubMed

The studies on the permeability of triprolidine through ethylene-vinyl acetate (EVA) copolymer membrane using two-chamber diffusion cell was carried out to develop the controlled delivery system. To evaluate the effect of drug concentration in reservoir, polyethylene glycol (PEG) 400 was added to saline solution as a solubilizer and a sink condition was maintained in the receptor solution. The permeation rate of drug through EVA membrane was proportional to PEG 400 volume fraction. A linear relationship existed between the permeation rate and the reciprocal of the membrane thickness. Triprolidine-containing matrix was fabricated with EVA copolymer to control the release of the drug. The plasticizers was added for preparing the pore structure of EVA membranes to increase the drug release. The effects of PEG 400, vinyl acetate (VA) contents of EVA, membrane thickness, drug concentration, temperature, and plasticizers, on drug release were studied. The release rate of drug from the EVA matrix increased with PEG 400 volume fraction, increased temperature and drug loading doses. An increased vinyl acetate comonomer content in EVA membrane increased the drug release rate and permeability coefficient. Among the plasticizers used such as alkyl citrates and phthalates, tetra ethyl citrate showed the best enhancing effects showing the enhancement factor of 1.88. The release of triprolidine from the EVA matrix follows a diffusion controlled model, where the quantity released per unit area is proportional to the square root of time. The controlled release of triprolidine could be achieved using the EVA polymer including the plasticizer. PMID:12191692

Shin, Sang-Chul; Lee, Hyun-Jin

2002-09-01

44

Controlled release of triprolidine using ethylene-vinyl acetate membrane and matrix systems  

Microsoft Academic Search

The studies on the permeability of triprolidine through ethylene-vinyl acetate (EVA) copolymer membrane using two-chamber diffusion cell was carried out to develop the controlled delivery system. To evaluate the effect of drug concentration in reservoir, polyethylene glycol (PEG) 400 was added to saline solution as a solubilizer and a sink condition was maintained in the receptor solution. The permeation rate

Sang-Chul Shin; Hyun-Jin Lee

2002-01-01

45

Effect of Additive Concentration on Cellulose Acetate Blend Membranes-Preparation, Characterization and Application Studies  

Microsoft Academic Search

Ultrafiltration techniques have particular advantages for simultaneous purification, concentration, and fractionation of macromolecules. A comparative study is presented on novel ultrafiltration polymeric blend membranes based on cellulose acetate (CA) prepared in the absence and presence of polymeric additives such as polyethylene Glycol 200 (PEG) and polyvinylpyrrolidone (PVP) by phase inversion technique using N,N?-dimethylformamide (DMF) as solvent. Polymer blend composition, additive

S. Vidya; A. Vijayalakshmi; A. Nagendran; D. Mohan

2008-01-01

46

Tailoring the properties of asymmetric cellulose acetate membranes by gas plasma etching.  

PubMed

Cellulose triacetate (CTA) ultrafilters and cellulose acetate blend (CAB) desalination membranes were treated with a radiofrequency gas plasma (tetrafluoromethane (CF(4)) or carbon dioxide (CO(2)), 47-49 W, 0.04-0.08 mbar). Treatment times were varied between 15 s and 120 min. The plasma-treated top layer of the membranes was characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, and contact angle measurements to obtain information about surface structure, chemistry, and wettability, respectively. The membrane properties (e.g., permeability, selectivity, fouling) were studied by waterflux measurements, molecular weight cutoff measurements, and fouling experiments with bovine serum albumin. CO(2) plasma treatment resulted in gradual etching of the membrane's dense top layer. Permeation and selectivity changed significantly for treatment times of 0-15 min for CTA and 5-60 min for CAB membranes. Moreover, CTA membranes were hydrophilized during CO(2) plasma treatment whereas CF(4) plasma treatment led to hydrophobic surfaces due to strong fluorination of the top layer. This study shows that gas plasma etching can tailor the properties of asymmetric cellulose acetate membranes by simultaneously modifying the chemistry and structure of the top layer. The low fouling properties of CTA membranes were thereby largely maintained. PMID:16290368

Olde Riekerink, M B; Engbers, G H M; Wessling, M; Feijen, J

2002-01-15

47

Preparation and Characterization of Cellulose Acetate?Sulfonated Poly (Ether Imide) Blend Ultrafiltration Membranes and their Applications  

Microsoft Academic Search

Modification of polymeric membrane materials by incorporation of hydrophilicity results in membranes with low fouling behavior and high flux. Hence, polyetherimide (PEI) was functionalized by sulfonation and ultrafiltration membranes were prepared based on cellulose acetate (CA) and sulfonated poly (ether imide) (SPEI) in various blend compositions in N?methyl?2?pyrrolidone (NMP) as solvent by phase inversion technique. Prepared membranes were subjected to

A. Nagendran; S. Vidya; D. Mohan

2008-01-01

48

Preparation, characterization and effect of annealing on performance of cellulose acetate\\/sulfonated polysulfone and cellulose acetate\\/epoxy resin blend ultrafiltration membranes  

Microsoft Academic Search

Polymeric membranes based on cellulose acetate (CA)––sulfonated polysulfone blends at three different polymer compositions were prepared by solution blending and phase inversion technique, characterized and subjected to annealing at 70, 80 and 90 °C. The permeate water flux, separation of bovine serum albumin and its flux by the blend membranes before and after thermal treatment, have been compared and discussed.

R Mahendran; R Malaisamy; D Mohan

2004-01-01

49

Study of ABO blood types by combining membrane electrophoresis with surface-enhanced Raman spectroscopy  

NASA Astrophysics Data System (ADS)

The molecular characterization of ABO blood types, which is clinically significant in blood transfusion, has clinical and anthropological importance. Polymerase chain reaction sequence-based typing (PCR-SBT) is one of the most commonly used methods for the analysis of genetic bases of ABO blood types. However, such methods as PCR-SBT are time-consuming and are high in demand of equipments and manipulative skill. Here we showed that membrane electrophoresis based SERS method employed for studying the molecular bases of ABO blood types can provide rapidand easy-operation with high sensitivity and specificity. The plasma proteins were firstly purified by membrane electrophoresis and then mixed with silver nanoparticles to perform SERS detection. We use this method to classify different blood types, including blood type A (n=13), blood type B (n=9) and blood type O (n=10). Combination of principal component analysis (PCA) and liner discriminant analysis (LDA) was then performed on the SERS spectra of purified albumin, showing good classification results among different blood types. Our experimental outcomes represent a critical step towards the rapid, convenient and accurate identification of ABO blood types.

Wang, Jing; Lin, Juqiang; Huang, Zufang; Sun, Liqing; Shao, Yonghong; Lu, Peng; Shi, Wei; Lin, Jinyong; Chen, Rong

2012-12-01

50

Enzymatic activation of cellulose acetate membrane for reducing of protein fouling.  

PubMed

In this study, the surface of cellulose acetate (CA) ultrafiltration membrane was activated with serine protease (Savinase) enzyme to reduce protein fouling. Enzyme molecules were covalently immobilized with glutaraldehyde (cross-linking agent) onto the surface of CA membranes. The membrane activation was verified using filtration experiments and morphological analysis. Scanning electron microscopy (SEM) images and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy of the activated membrane when compared with raw membrane were confirmed that the enzyme was immobilized onto the membrane surface. The immobilization efficiencies changed from 13.2 to 41.2% according to the enzyme ratios from 2.5 to 10.0 mg/mL. However, the permeability values decreased from 232±6 to 121±4 L/m(2) h bar with increasing enzyme concentration from 2.5 to 10.0 mg/mL. In fouling experiments, bovine serum albumin (BSA) was used as the protein model solution and activated sludge was used as the model biological sludge. Enzyme-activated membranes exhibited good filtration performances and protein rejection efficiencies were compared with raw CA membrane. Also the relative flux reduction (RFR) ratios of membranes were calculated as 97% and 88% for raw CA and enzyme-activated membranes (5 mg/mL savinase), respectively. The membrane activated with Savinase enzyme could be proposed as a surface treatment method before filtration to mitigate protein fouling. PMID:22218336

Koseoglu-Imer, Derya Y; Dizge, Nadir; Koyuncu, Ismail

2012-04-01

51

Study of polydimethylsiloxane/aromatic polyamide laminated membranes for separation of acetic acid/water mixtures by pervaporation process  

SciTech Connect

Separation of acetic acid/water mixtures by pervaporation was attempted over a range of compositions using polydimethylsiloxane (PDMS), aromatic polyamide (PA), and laminated polydimethylsiloxane-aromatic polyamide membranes. PDMS membranes are hydrophobic and acetic acid selective, whereas PA membranes are hydrophilic and water selective. When PDMS and PA membranes were laminated, with PDMS on the top side and in contact with the feed, water selectivity of the bottom PA membrane was intensified. On the other hand, when the PA membrane was on the top side and in contact with the feed, the selectivity was lowered. 10 refs., 4 figs.

Deng, S.; Sourirajan, S.; Matsuura, T. (Univ. of Ottawa (Canada))

1994-06-01

52

Study of gas separation properties of ethylene vinyl acetate (EVA) copolymer membranes prepared via phase inversion method  

Microsoft Academic Search

The gas separation properties of ethylene vinyl acetate (EVA) membranes containing 18 and 28wt% of vinyl acetate (VA) were investigated in this study. The effects of membrane preparation conditions, such as thermal and thermal\\/wet phase inversion, and the type of solvent on the gas separation properties of EVA membranes were investigated. The permeation of pure O2, N2, CH4, and CO2

Seyyed Abbas Mousavi; Morteza Sadeghi; M. Mohammad Yusef Motamed-Hashemi; Mahdi Pourafshari Chenar; Reza Roosta-Azad; Mohammad Sadeghi

2008-01-01

53

Western Blotting Using Microchip Electrophoresis Interfaced to a Protein Capture Membrane  

PubMed Central

Western blotting is a commonly used assay for proteins. Despite the utility of the method, it is also characterized by long analysis times, manual operation, and lack of established miniaturized counterpart. We report a new way to Western blot which addresses these limitations. In the method, sodium dodecyl sulfate (SDS)-protein complexes are separated by sieving electrophoresis in a microfluidic device or chip. The chip is interfaced to a moving membrane so that proteins are captured in discrete zones as they migrate from the chip. Separations of SDS-protein complexes in the molecular weight range of 11 to 155 kDa were completed in 2 min with 4 × 104 theoretical plates at 460 V/cm. Migration time and peak area relative standard deviations were 3–6% and 0.2% respectively. Detection limit for actin was 0.7 nM. Assays for actin, AMP-kinase, carbonic anhydrase, and lysozyme are shown to demonstrate versatility of the method. Total analysis time including immunoassay was 22–32 min for a single sample. Because processing membrane for immunoassay is the slow step of the assay, sequential injections from different reservoirs on the chip and capture in different tracks on the same membrane allow increased throughput. As a demonstration, 9 injections were collected on one membrane and analyzed in 43 min (~5 min/sample). Further improvements in throughput are possible with more reservoirs or parallel channels.

Jin, Shi; Anderson, Gwendolyn J.; Kennedy, Robert T.

2013-01-01

54

High resolution clear native electrophoresis is a good alternative to blue native electrophoresis for the characterization of the Escherichia coli membrane complexes.  

PubMed

Blue native electrophoresis (BNE) has become the most popular method for the global analysis of membrane protein complexes. Although it has been shown to be very useful for that purpose, it can produce the dissociation of complexes with weak interactions and, due to the use of Coomassie Brilliant Blue, does not allow the subsequent application of fluorimetric and/or enzymatic techniques. Recently, we have successfully used the high resolution clear native electrophoresis (hrCNE) for the analysis of Neisseria meningitidis outer membrane porin complexes. The aim of this study was to determine the composition of the complexome of the Escherichia coli envelope by using hrCNE and to compare our results with those previously obtained using BNE. The bidimensional electrophoresis approaches used, hrCN/hrCNE and hrCN/SDS-PAGE, coupled to mass spectrometry allowed a detailed analysis of the complexome of E. coli membranes. For the first time, the three subunits of the formate dehydrogenase FDH-O were identified forming a single complex and hrCNE also allowed the identification of both the HflK and HflC proteins as components of the HflA complex. This technique also allowed us to suggest a relationship between OmpF and DLDH and, although OmpA is considered to be monomeric in vivo, we found this protein structured as homodimers. Thus hrCNE provides a good tool for future analyses of bacterial membrane proteins and complexes and is an important alternative to the commonly used BNE. PMID:24845470

Diéguez-Casal, Ernesto; Freixeiro, Paula; Costoya, Liliana; Criado, M Teresa; Ferreirós, Carlos; Sánchez, Sandra

2014-07-01

55

In situ modification on cellulose acetate hollow fiber membrane modified with phospholipid polymer for biomedical application  

Microsoft Academic Search

The hollow fiber membrane (HFM) made from synthetic polymers need improvement in terms of hemocompatibility or biocompatibihty, for use in the medical field. In this study, cellulose acetate (CA) HFM modified with the water-soluble amphiphilic 2-methacryloyloxyethyl phosphorylcholine (MPC) copolymer (poly (MPC-co-n-butyl methacrylate) (PMB80, MPC:BMA=80:20 (mol%)) was prepared by a dry-jet wet spinning process. The PMB80 was coated on the CA

Sang Ho Ye; Junji Watanabe; Yasuhiko Iwasaki; Kazuhiko Ishihara

2005-01-01

56

Study on Preparation and Performance of Modified Polyvinyl Chloride-Co-vinyl Acetate Microfiltration Membranes  

Microsoft Academic Search

In this paper, flat-sheet microfiltration membranes were prepared from modified polyvinyl chloride-vinyl acetate (VC-co-VAc) material with hydroxyl group, VC-co-VAc-OH, by phase inversion technique. The influences of casting solution composition (polymer concentration, additive types and content) and preparation conditions (coagulation temperature, evaporation time of solvent and the relative humidity in the environment) on pure water flux, retention and pore size distribution

Jing Zhang; Wenjuan Li; Zhan Wang; Xiao Ye; Longyue Shi; Wentao Yang; Sha Chen

2012-01-01

57

Pervaporation characteristics of polyetherimide\\/?-alumina composite membrane for a quaternary equilibrium mixture of acetic acid-ethanol-ethyl acetate-water  

Microsoft Academic Search

Polyetherimide\\/?-alumina composite membrane has been prepared by dipping method for further reactor application. Separation\\u000a factors and permeances for a quaternary acetic acid-ethanol-ethyl acetate-water equilibrium feed mixture have been measured\\u000a on the composite membrane in the range of temperature from 303 K up to 343 K and space time from 27 sec to 27,000 sec at a\\u000a permeate-side pressure of 2.67?10-3

Byoung-Gi Park

2004-01-01

58

Adsorption of N-alkylpyridinium chlorides from water and salt solutions on cellulose acetate ultrafiltration membranes  

SciTech Connect

A study has been made of the adsorption of three homologues in the N-alkylpyridinium chloride series from water and salt solutions, over a wide range of concentrations, on cellulose acetate ultrafiltration membranes, Grades UAM-500 and UAM-150. When adsorption takes place from true solutions, the membrane surface is hydrophobized. In the region of micellar solutions, nonassociated molecules and micelles are adsorbed in the mesopores and supermicropores, forming a mosaic adsorption layer. The thickness of the modifying layer depends on the length of the hydrophobic radical and on the composition of the system.

Klimenko, N.A.; Yaroshenko, N.A.; Kondratova, T.B.

1988-09-01

59

Development of a LCST membrane forming system for cellulose acetate ultrafiltration hollow fiber  

Microsoft Academic Search

A novel lower critical solution temperature (LCST) membrane forming system containing cellulose acetate (CA)\\/poly (vinyl pyrrolidone) (PVP 360K)\\/N-methyl-2-pyrrolidone (NMP)\\/1,2-propanediol with a weight ratio of 24.0:5.0:62.6:8.4 had been developed. CA hollow fiber ultrafiltration (UF) membranes were fabricated using the dry–wet spinning technique. The fibers were post-treated with a 200mg\\/L hypochlorite solution over a period of 6h at pH 7. The experimental

Jian-Jun Qin; Maung Htun Oo; Yi-Ming Cao; Leng-Siang Lee

2005-01-01

60

Preparation and characterisation of poly (amide-imide) incorporated cellulose acetate membranes for polymer enhanced ultrafiltration of metal ions  

Microsoft Academic Search

Polymeric membranes intended to use in industrial separations must maintain excellent thermal and mechanical properties over their targeted operating conditions. Therefore, cellulose acetate (CA) membranes with superior properties were prepared by phase inversion technique using high performance thermoplastic poly (amide-imide) (PAI) as the modification agent. The prepared membranes were characterised using scanning electron microscopy (SEM), atomic force microscopy (AFM), differential

S. Rajesh; P. Maheswari; S. Senthilkumar; A. Jayalakshmi; D. Mohan

2011-01-01

61

Phase inversion cellulose acetate membranes for suppression of protein interferences in anodic stripping voltammetry 2 1. Improvement of the membrane preparation procedure  

Microsoft Academic Search

Phase inversion (PI) cellulose acetate membranes were cast on glassy carbon electrodes from a solution containing acetone as solvent and aqueous magnesium perchlorate as pore former. It is shown that a significant improvement of the reproducibility and permselective properties of the membrane is obtained by allowing complete evaporation of the solvent in a controlled humidity environment before the membrane is

Boy Hoyer; Nina Jensen

1996-01-01

62

Formation of micro- and nano-spheric particles (filter dust) during the preparation of cellulose acetate membranes  

Microsoft Academic Search

Membranes were prepared from six samples of cellulose acetate (CA) differing in their average molecular weight (75–260kg\\/mole) and molecular weight distribution using methyl acetate as solvent and 2-propanole as precipitant. The routes through the phase diagram and the evaporation times were varied in these experiments. Electron microscopy demonstrates that the amount of filter dust (CA particles deposited on the membrane

J. Eckelt; S. Loske; M. C. Gonçalves; B. A. Wolf

2003-01-01

63

Cellulose acetate hollow fiber ultrafiltration membranes made from CA\\/PVP 360 K\\/NMP\\/water  

Microsoft Academic Search

Hydrophilic hollow fiber ultrafiltration (UF) membranes have been prepared from a new dope solution containing cellulose acetate (CA)\\/poly(vinyl pyrrolidone) (PVP 360K)\\/N-methyl-2-pyrrolidone (NMP)\\/water with a mass ratio of 19.0\\/5.0\\/74.8\\/1.2 by using a dry-jet wet spinning process. The effect of air-gap length was studied. The as-spun fibers were post-treated by means of a hypochlorite solution of 200mgl?1 (200ppm) over different duration. The

Jian-Jun Qin; Ying Li; Leng-Siang Lee; Hsiaowan Lee

2003-01-01

64

Tunable membranes for free-flow zone electrophoresis in PDMS microchip using guided self-assembly of silica microbeads.  

PubMed

In this paper, we evaluate the strategy of using self-assembled microbeads to build a robust and tunable membrane for free-flow zone electrophoresis in a PDMS microfluidic chip. To fabricate a porous membrane as a salt bridge for free-flow zone electrophoresis, we used silica or polystyrene microbeads between 3-6 ?m in diameter and packed them inside a microchannel. After complete evaporation, we infiltrated the porous microbead structure with a positively or negatively charged hydrogel to modify its surface charge polarity. Using this device, we demonstrated binary sorting (separation of positive and negative species at a given pH) of peptides and dyes in standard buffer systems without using sheath flows. The sample loss during sorting could be minimized by using ion selectivity of hydrogel-infiltrated microbead membranes. Our fabrication method enables building a robust membrane for pressure-driven free-flow zone electrophoresis with tunable pore size as well as surface charge polarity. PMID:24251795

Song, Yong-Ak; Wu, Lidan; Tannenbaum, Steven R; Wishnok, John S; Han, Jongyoon

2013-12-17

65

Optical, bactericidal and water repellent properties of electrospun nano-composite membranes of cellulose acetate and ZnO  

Microsoft Academic Search

In this report, ZnO nanoparticles embedded cellulose acetate (CA) fibrous membrane with multifunctional properties have been prepared through electrospinning method. The morphology of the electrospun composite membrane was analyzed by Scanning Electron Microscope (SEM). It was found that the polymer concentration in the solution has a significant effect on the morphology of the fibers. The optical property of the sample

S. Anitha; B. Brabu; D. John Thiruvadigal; C. Gopalakrishnan; T. S. Natarajan

66

Adsorptive removal of phenolic compounds using cellulose acetate phthalate-alumina nanoparticle mixed matrix membrane.  

PubMed

Mixed matrix membranes (MMMs) were prepared using alumina nanoparticles and cellulose acetate phthalate (CAP) by varying concentration of nanoparticles in the range of 10 to 25wt%. The membranes were characterized by scanning electron micrograph, porosity, permeability, molecular weight cut off, contact angle, surface zeta potential, mechanical strength. Addition of nanoparticles increased the porosity, permeability of the membrane up to 20wt% of alumina. pH at point of zero charge of the membrane was 5.4. Zeta potential of the membrane became more negative up to 20wt% of nanoparticles. Adsorption of phenolic derivatives, catechol, paranitrophenol, phenol, orthochloro phenol, metanitrophenol, by MMMs were investigated. Variation of rejection and permeate flux profiles were studied for different solutes as a function of various operating conditions, namely, solution pH, solute concentration in feed and transmembrane pressure drop. Difference in rejection of phenolic derivatives is consequence of interplay of surface charge and adsorption by alumina. Adsorption isotherm was fitted for different solutes and effects of pH were investigated. Catechol showed the maximum rejection 91% at solution pH 9. Addition of electrolyte reduced the rejection of solutes. Transmembrane pressure drop has insignificant effects on solute rejection. Competitive adsorption reduced the rejection of individual solute. PMID:24333710

Mukherjee, Raka; De, Sirshendu

2014-01-30

67

Suppressing glucose uptake and acetic acid production increases membrane protein overexpression in Escherichia coli  

PubMed Central

Background The production of integral membrane spanning proteins (IMP's) constitutes a bottleneck in pharmaceutical development. It was long considered that the state-of-the-art was to produce the proteins as inclusion bodies using a powerful induction system. However, the quality of the protein was compromised and the production of a soluble protein that is incorporated into the membrane from which it is extracted is now considered to be a better method. Earlier research has indicated that a slower rate of protein synthesis might overcome the tendency to form inclusion bodies. We here suggest the use of a set of E. coli mutants characterized by a slower rate of growth and protein synthesis as a tool for increasing the amount of soluble protein in high- throughput protein production processes. Results A set of five IMP's was chosen which were expressed in three mutants and the corresponding WT cell (control). The mutations led to three different substrate uptake rates, two of which were considerably slower than that of the wild type. Using the mutants, we were able to express three out of the five membrane proteins. Most successful was the mutant growing at 50% of the wild type growth rate. A further effect of a low growth rate is a low acetic acid formation, and we believe that this is a possible reason for the better production. This hypothesis was further supported by expression from the BL21(DE3) strain, using the same plasmid. This strain grows at a high growth rate but nevertheless yields only small amounts of acetic acid. This strain was also able to express three out of the five IMP's, although at lower quantities. Conclusions The use of mutants that reduce the specific substrate uptake rate seems to be a versatile tool for overcoming some of the difficulties in the production of integral membrane spanning proteins. A set of strains with mutations in the glucose uptake system and with a lower acetic acid formation were able to produce three out of five membrane proteins that it was not possible to produce with the corresponding wild type.

2011-01-01

68

Poly(vinylidene fluoride- co-hexafluoropropene) (PVDF-HFP) membranes for ethyl acetate removal from water  

Microsoft Academic Search

In this study, poly(vinylidene fluoride-co-hexafluoropropene) (PVDF-HFP) with low crystallinity was applied as the membrane material for pervaporative separating ethyl acetate (EtAc) from its aqueous solutions. The drying conditions during membrane fabrication by means of casting the PVDF-HFP solution dominated the obtained membrane morphologies when the polar solvents such as dimethylacetamide (DMAc) and acetone were used. It was demonstrated that both

Xiuzhi Tian; Xue Jiang

2008-01-01

69

Effect of formation conditions of poly(ethylene- co-vinyl acetate) membrane on the membrane physical structure and pervaporation properties in the recovery of ethyl acetate from aqueous solution  

Microsoft Academic Search

The solution properties, intrinsic viscosity [?] and Huggins constant KH of ethylene-vinyl acetate (EVA) copolymer with 38wt% vinyl acetate content (EVA38) in solvents of chloroform (CF), 1,2-dichloroethane (DCE) and cyclohexane (CYH) were measured by an Ubbelohode viscometer. The physical structure and pervaporation performances of the EVA membranes cast from different solvents were also investigated by wide-angle X-ray diffraction (WAXD), contact

Yun-Xiang Bai; Jin-Wen Qian; Qiang Zhao; Zhi-Hui Zhu; Peng Zhang

2007-01-01

70

Method for the preparation of cellulose acetate flat sheet composite membranes for forward osmosis—Desalination using MgSO 4 draw solution  

Microsoft Academic Search

A lab scale method for the preparation of defect free flat sheet composite membranes for forward osmosis (FO) has been developed. Membranes containing a thin layer of cellulose acetate (CA) cast on a nylon fabric of 50?m thick were prepared by phase inversion in water. Cellulose acetate (CA) membranes with an overall thickness of 70–80?m have been prepared with lactic

M. Sairam; E. Sereewatthanawut; K. Li; A. Bismarck; A. G. Livingston

2011-01-01

71

Comparison of protein mixtures in aqueous humor by membrane preconcentration - capillary electrophoresis - mass spectrometry.  

PubMed

The significance of proteomic research is coupled with the recent exponential growth of these investigations. Currently, the most popular techniques used for these studies include the coupling of 1- and 2-dimensional electrophoresis with mass spectrometric analysis of the extracted and digested proteins. However, detection limits of gel staining methods have led to a search for complimentary techniques that afford the detection of lower concentrations of biologically relevant proteins. In the present studies, we have evaluated the applicability of on-line capillary electrophoresis - mass spectrometry (CE-MS) for this application. Specifically, we used membrane preconcentration-CE-MS (mPC-CE-MS) to analyze 13 samples of human aqueous humor (AH) from patients with various ocular pathologies (cataract, cataract plus glaucoma, and cataract plus pseudoexfoliation syndrome). This approach enabled rapid analysis of a relatively large volume (1 microL of each specimen, and a protein map for each was created. Measured average molecular weights (Mr) were used to tentatively identify proteins after search of the SWISS-PROT database using TagIdent from ExPaSy. Among those proteins tentatively identified are beta-2 microglobulin (Mr 11731.2), apolipoprotein A1 (Mr 28078.6) and serum albumin (Mr 66400). Proteins with Mr of 4349 (unidentified), 11731.2 (beta-2 microglobulin), 13400-14100 (immunoglobulin fragments), 28078.2 (apolipoprotein A1) and approximately 68000 (serum albumin) were observed in the majority of specimens. Generally no significant differences were noted in the protein composition of aqueous humor samples from different pathologies. However, the absence of an Mr 13345 protein and its oxidized form (Mr 13361) in samples from patients with pseudoexfoliation syndrome was noted. Occasionally the alpha-and beta-chains of hemoglobin, a contaminant in aqueous humor introduced during sampling, were also detected. We conclude from these studies that mPC-CE-MS is an attractive complimentary technique for proteome research, as this approach enables direct mapping and characterization of low concentrations of proteins that are present in complex physiologically derived fluids. PMID:9788321

Rohde, E; Tomlinson, A J; Johnson, D H; Naylor, S

1998-10-01

72

A novel blood plasma analysis technique combining membrane electrophoresis with silver nanoparticle-based SERS spectroscopy for potential applications in noninvasive cancer detection  

Microsoft Academic Search

Combining membrane electrophoresis with silver nanoparticle-based surface-enhanced Raman spectroscopy (SERS), we have developed a novel method for blood plasma analysis for cancer detection applications. In this method, total serum proteins are isolated from blood plasma by membrane electrophoresis and mixed with silver nanoparticles to perform SERS spectral analysis. The obtained SERS spectra present information-rich, fingerprint-type signatures of the biochemical constituents

Juqiang Lin; Rong Chen; Shangyuan Feng; Jianji Pan; Yongzeng Li; Guannan Chen; Min Cheng; Zufang Huang; Yun Yu; Haishan Zeng

2011-01-01

73

Phorbol myristate acetate stimulates ATP-dependent calcium transport by the plasma membrane of neutrophils.  

PubMed Central

We studied the effect of phorbol myristate acetate (PMA) on the plasma membrane ATP-dependent calcium pump in neutrophils. Plasma membrane-enriched fractions ("podosomes") from PMA-stimulated guinea pig neutrophils exhibited a twofold stimulation of ATP-dependent calcium transport when compared with control podosomes. The stimulatory effect was rapid (beginning less than 2 min after exposure to PMA) and reached maximal values within 5 min. PMA increased the maximum velocity but not the affinity of the calcium pump for Ca++. Pump activation was not preceded by a rise in cytosolic free calcium concentration [Ca++]i, as assessed by the intracellularly trapped fluorescent calcium indicator Quin 2, but instead slightly lowered [Ca++]i and prevented the rise in [Ca++]i normally induced by the chemotactic peptide formyl-methionyl-leucyl-phenylalanine. These results suggest that the calcium pump in the plasma membrane of neutrophils may be stimulated by calcium-independent pathways, and that this activation could be one of the earliest events mediating some of the effects of phorbol esters.

Lagast, H; Pozzan, T; Waldvogel, F A; Lew, P D

1984-01-01

74

Composite membrane of niobium(V) oxide and cellulose acetate: Preparation and characterization  

SciTech Connect

Composite membranes of niobium(V) oxide and cellulose acetate (Cel/Nb{sub 2}O{sub 5}) were prepared with the following Nb{sub 2}O{sub 5} loadings (in wt%): 1.1, 6.1, 9.8, 15.6, and 20.9. The thermal stability of the membranes slightly decreased in relation to the pure membrane on incorporation of the metal oxide into the matrix. Scanning electron microscopy and niobium mapping with an X-ray EDS microprobe showed that the metal oxide particles are homogeneously dispersed in the matrix. The electronic absorption bands indicated that the oxide particle size varies from that of the monomer to those of oligomer species on increased Nb{sub 2}O{sub 5} loading in the matrix. The dispersed oxide possesses mainly Lewis acid character, a clear indication that on increasing the oxide loading in the matrix, the coordination number of the metal is not saturated by formation of the Nb-O-Nb bond. These materials can be useful in ion-exchange process, as supports for enzymes, in catalytic reactions, and in reverse osmosis experiments.

Campos, E.A.; Gushikem, Y. [Unicamp, Campinas, Sao Paulo (Brazil). Inst. de Quimica] [Unicamp, Campinas, Sao Paulo (Brazil). Inst. de Quimica

1997-09-01

75

Membrane-supported liquid-liquid-liquid microextraction combined with anion-selective exhaustive injection capillary electrophoresis-ultraviolet detection for sensitive analysis of phytohormones.  

PubMed

A novel method based on off-line membrane-supported liquid-liquid-liquid microextraction (MS-LLLME) combined with on-column anion-selective exhaustive injection (ASEI) capillary electrophoresis-ultraviolet (CE-UV) detection was established for the analysis of seven phytohormones (abscisic acid (ABA), jasmonic acid (JA), 2,4-dichlorophenoxyacetic acid (2,4-D), 1-naphthalene acetic acid (NAA), indole-3-acetic acid (IAA), salicylic acid (SA) and gibberellic acid (GA)). In MS-LLLME, the target phytohormones were extracted from the acid donor phase to the alkaline acceptor phase, and the acceptor solutions were directly analyzed by ASEI-CE-UV. Under the optimal experimental conditions, the analytical performance of the method was evaluated. The limits of detection (LODs) of ABA, JA, 2,4-D, NAA, IAA, SA and GA were determined to be 1.00, 2.21, 0.33, 0.17, 0.67, 0.05 and 16.5ng/mL, respectively. The relative standard deviations (RSDs, n=7) ranged from 4.7% to 12.9%, and the enrichment factors were in the range of 307 to 20,160. The proposed method was successfully applied for the determination of multiple phytohormones in banana, cabbage and cucumber extracts, and ABA, IAA and SA were detected in these samples. The recoveries for the spiked samples were in the range of 79.0 to 116.4%. The proposed method was demonstrated to be suitable for the simultaneous quantification of multiple phytohormones with high sensitivity and good sample cleanup ability. PMID:24720904

Huang, Linfang; He, Man; Chen, Beibei; Hu, Bin

2014-05-23

76

Well-constructed cellulose acetate membranes for forward osmosis: Minimized internal concentration polarization with an ultra-thin selective layer  

Microsoft Academic Search

The design and engineering of membrane structure that produces low salt leakage and minimized internal concentration polarization (ICP) in forward osmosis (FO) processes have been explored in this work. The fundamentals of phase inversion of cellulose acetate (CA) regarding the formation of an ultra-thin selective layer at the bottom interface of polymer and casting substrate were investigated by using substrates

Sui Zhang; Kai Yu Wang; Tai-Shung Chung; Hongmin Chen; Y. C. Jean; Gary Amy

2010-01-01

77

Light scattering and membrane formation studies on polysulfone solutions in NMP and in mixed solvents of NMP and ethyl acetate  

Microsoft Academic Search

The relationship between the characteristics of the polymer dope solution and the skin formation mechanism as well as the performance of the asymmetric membrane has been investigated. The solution characteristics have been studied on the polysulfone (PSf) dope solution as a function of the concentrations of both polymer and the cosolvent, ethyl acetate (EA), by dynamic light scattering. An anomalous

Jongok Won; Yong Soo Kang; Hyun Chae Park; Un Young Kim

1998-01-01

78

Development and optimization of a capillary zone electrophoresis technique for simultaneous determination of miconazole nitrate and hydrocortisone acetate in a cream pharmaceutical formulation.  

PubMed

A simple, fast, inexpensive, and reliable capillary zone electrophoresis (CZE) method for the determination of a mixture of miconazole nitrate (MCZ) and hydrocortisone acetate (HCZ) in a cream formulation has been developed and validated. Optimum conditions were sodium dihydrogen phosphate buffer (50 mM, pH 4) and 30 kV applied voltage in a 85 cm x 75 pm id capillary. Direct UV detection at 230 nm led to adequate sensitivity without interference from the sample excipients. MCZ and HCZ migrated in approximately 165 and 415 s, respectively. The analytical curves had a coefficient of correlation, r, of 0.9999 and 0.9996 for MCZ and HCZ, respectively. The LOD and LOQ were 0.28 and 0.93 microg/mL for MCZ and 0.38 and 1.27 microg/mL for HCZ, respectively. Thus, excellent accuracy and precision were obtained. Recoveries varied from 98 to 102%, and intraday and interday precision, calculated as the RSD, were less than 2.0% for each drug. The proposed CZE method displayed advantageous performance characteristics and can be considered suitable for QC of the MCZ and HCZ cream formulation. PMID:24645507

Korany, Mohamed A; Maher, Hadir M; Galal, Shereen M; Ragab, Marwa A A

2013-01-01

79

Surface modification of commercial cellulose acetate membranes using surface-initiated polymerization of 2-hydroxyethyl methacrylate to improve membrane surface biofouling resistance  

Microsoft Academic Search

To improve biofouling resistance, cellulose acetate (CA) reverse osmosis membranes were modified by reacting surface hydroxyl groups with an atom transfer radical polymerization (ATRP) initiator, 2-bromoisobutyryl bromide, followed by polymeric grafting of 2-hydroxyethyl methacrylate (pHEMA) using activators regenerated by electron transfer (ARGET) ATRP. Thermogravimetric analysis (TGA), atomic force microscopy (AFM) and water contact angle (WCA) measurements of pristine and modified

Clare H. Worthley; Kristina T. Constantopoulos; Milena Ginic-Markovic; Rachel J. Pillar; Janis G. Matisons; Stephen Clarke

2011-01-01

80

An optimized procedure for sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of hydrophobic peptides from an integral membrane protein.  

PubMed

A procedure for successful analysis of the hydrophobic tryptic peptides of the Neurospora crassa plasma membrane H+-ATPase by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) is described. The features of this procedure that are essential for the best results include (i) treatment of the hydrophobic peptide samples with neat trifluoroacetic acid, (ii) dissolution and disaggregation of the hydrophobic peptide samples with SDS at 0 degrees C, (iii) SDS-PAGE of the hydrophobic peptide samples in gels containing a 200:1 ratio of acrylamide to bisacrylamide and a 5-20% convex acrylamide gradient, and (iv) silver-staining of the gels after electrophoresis. This method results in the reproducible resolution and visualization of the H+-ATPase hydrophobic tryptic peptides, which range in size from ca. 5 to 21 kDa, as well as other peptides and proteins ranging in size from ca. 2.5 to 150 kDa. The methods described should also prove useful in other studies where resolution and visualization of hydrophobic peptides of integral membrane proteins are required. PMID:2525882

Hennessey, J P; Scarborough, G A

1989-02-01

81

Fouling propensity and separation efficiency of epoxidated polyethersulfone incorporated cellulose acetate ultrafiltration membrane in the retention of proteins  

NASA Astrophysics Data System (ADS)

Epoxidated polyethersulfone (EPES) incorporated cellulose acetate (CA) ultrafiltration membranes were prepared by diffusion induced precipitation technique in the absence and presence of pore former polyethyleneglycol-600. Effect of blend ratio on the compatibility, thermal stability, mechanical strength, hydrophilicity, morphology, pure water flux, protein adsorption resistance, protein separation efficiency and fouling propensity of the CA/EPES blend membranes was evaluated. Addition of EPES results in the formation of thin separating layer and spongy sub layer in CA/EPES blend membranes. The efficiency of these membranes in the separation of commercially important proteins such as bovine serum albumin, egg albumin, pepsin and trypsin was studied and found to be enhanced as compared to CA membranes. The fouling-resistant capability of the membranes was studied by bovine serum albumin as the model foulant and flux recovery ratio of the membranes were calculated. Attempts have been made to correlate the changes in membrane morphology with pure water flux, hydraulic resistance, thermal and mechanical stability, separation efficiency and antifouling property of the CA/EPES membranes. The optimal combination of CA and EPES, thus allows the preparation of high performance UF membranes which are sufficiently dense to retain proteins and at the same time give economically viable fluxes.

Jayalakshmi, A.; Rajesh, S.; Mohan, D.

2012-10-01

82

Selective oxidation of ethanol to acetic acid in highly efficient polymer electrolyte membrane-direct ethanol fuel cells  

Microsoft Academic Search

The selective conversion of ethanol into potassium acetate with concomitant production of electrical energy has been achieved in both passive and active direct fuel cells containing platinum-free electrodes and an anion-exchange polymer membrane. The power densities supplied by the passive systems at r.t. can be as high as 55mWcm?2, while the active systems can deliver up to 170mWcm?2 at 80°C.

Claudio Bianchini; Valentina Bambagioni; Jonathan Filippi; Andrea Marchionni; Francesco Vizza; Paolo Bert; Alessandro Tampucci

2009-01-01

83

A novel precursor composed of polycarbosilane and palladium(II) acetate for a SiC-based gas separation membrane  

Microsoft Academic Search

Organic-inorganic conversion process of a novel precursor composed of polycarbosilane and palladium(II) acetate was investigated in order to develop a SiC-based gas separation membrane. It was found that the precursor was converted to inorganic material forming Si-C-Si, Si-O-Si and Si-O-C network and evolving hydrogen, methane, ethane, carbon monoxide and carbon dioxide gases in a temperature range of 350-1000K. Furthermore, it

Akira Idesaki; Masaki Sugimoto; Masahito Yoshikawa

2011-01-01

84

Effects of annealing on the microstructure and performance of cellulose acetate membranes for pressure-retarded osmosis processes  

Microsoft Academic Search

The effects of annealing on the microstructure and performance of cellulose acetate (CA) forward osmosis (FO) hollow fiber membranes have been studied. The mean pore radius decreases from 0.63nm to 0.39, 0.36, 0.30 and 0.30 upon annealing at 70, 80, 85 and 90°C, respectively. The density of free volume in the depth range of 0.31–1.33?m significantly decreases with depth with

Jincai Su; Sui Zhang; Hangzheng Chen; Hongmin Chen; Y. C. Jean; Tai-Shung Chung

2010-01-01

85

Outer membrane protein profiles and multilocus enzyme electrophoresis analysis for differentiation of clinical isolates of Proteus mirabilis and Proteus vulgaris.  

PubMed

Outer membrane protein (MP) profiles and multilocus enzyme electrophoresis (MEE) analysis were used as tools for differentiating clinical isolates of Proteus spp. Fourteen distinct MP profiles were established by sodium dodecyl sulfate-urea polyacrylamide gel electrophoresis in 54 clinical isolates of Proteus spp. (44 strains identified as P. mirabilis and 10 strains identified as P. vulgaris). Forty-one isolates of P. mirabilis and eight isolates of P. vulgaris were grouped within six and three MP profiles, respectively. The remaining P. mirabilis and P. vulgaris isolates had unique profiles. MEE analysis was used to further discriminate among the strains belonging to the same MP groups. Thirty-five distinct electrophoretic types (ETs) were identified among P. mirabilis isolates. The isolates of P. mirabilis from the four most common MP groups were subgrouped into 30 ETs. All of the P. vulgaris strains had unique ETs. The results suggest that upon biochemical classification of Proteus isolates as P. mirabilis or P. vulgaris, further differentiation among strains of the same species can be obtained by the initial determination of MP profiles followed by MEE analysis of strains with identical MPs. PMID:1400963

Kappos, T; John, M A; Hussain, Z; Valvano, M A

1992-10-01

86

Outer membrane protein profiles and multilocus enzyme electrophoresis analysis for differentiation of clinical isolates of Proteus mirabilis and Proteus vulgaris.  

PubMed Central

Outer membrane protein (MP) profiles and multilocus enzyme electrophoresis (MEE) analysis were used as tools for differentiating clinical isolates of Proteus spp. Fourteen distinct MP profiles were established by sodium dodecyl sulfate-urea polyacrylamide gel electrophoresis in 54 clinical isolates of Proteus spp. (44 strains identified as P. mirabilis and 10 strains identified as P. vulgaris). Forty-one isolates of P. mirabilis and eight isolates of P. vulgaris were grouped within six and three MP profiles, respectively. The remaining P. mirabilis and P. vulgaris isolates had unique profiles. MEE analysis was used to further discriminate among the strains belonging to the same MP groups. Thirty-five distinct electrophoretic types (ETs) were identified among P. mirabilis isolates. The isolates of P. mirabilis from the four most common MP groups were subgrouped into 30 ETs. All of the P. vulgaris strains had unique ETs. The results suggest that upon biochemical classification of Proteus isolates as P. mirabilis or P. vulgaris, further differentiation among strains of the same species can be obtained by the initial determination of MP profiles followed by MEE analysis of strains with identical MPs. Images

Kappos, T; John, M A; Hussain, Z; Valvano, M A

1992-01-01

87

Comparison of polycarbonate and cellulose acetate membrane filters for isolation of Campylobacter concisus from stool samples.  

PubMed

One thousand seven hundred ninety-one diarrheic stool samples were cultivated for Campylobacter spp. We found a high prevalence of Campylobacter concisus with use of a polycarbonate filter (n = 114) compared to a cellulose acetate filter (n = 79) (P < .0001). The polycarbonate filter is superior to the commonly used cellulose acetate filter for detection of C. concisus. PMID:23743174

Nielsen, Hans Linde; Engberg, Jørgen; Ejlertsen, Tove; Nielsen, Henrik

2013-08-01

88

Capillary electrophoresis with capacitively coupled contactless conductivity detection: a universal tool for the determination of supported liquid membrane selectivity in electromembrane extraction of complex samples.  

PubMed

Monitoring the selectivity of supported liquid membranes (SLMs) is of paramount importance since the amount and type of compounds that are transferred across a SLM directly influence the transfer efficiency, reproducibility and accuracy. To apply a correct SLM in particular sample pretreatment, rapid determination of the transfer of analytes and matrix compounds across the SLM is necessary, which requires the use of an analytical method with universal detection technique. Capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C(4)D) has proven to be a useful tool for the determination of SLM selectivity. Background electrolyte solution consisting of 1M acetic acid (pH 2.4) was used for simultaneous separation and detection of three basic drugs (nortriptyline, haloperidol and loperamide) and major matrix components (inorganic cations, proteins, amino acids, etc.) after electromembrane extraction (EME) of standard solutions and complex samples. The CE-C(4)D method has evidenced for the first time that large proteins, such as human serum albumin, are efficiently retained on all examined SLMs and that transfer of other matrix components and the analytes is strongly SLM dependent. Excellent transfer of the analytes was achieved across SLMs impregnated with 2-nitrophenyl octyl ether (NPOE) or 1-ethyl-2-nitrobenzene, however, an increased co-extraction of interfering matrix components, which disabled quantitative determination of haloperidol with the current CE-C(4)D setup, was observed for the latter. After addition of a commonly used ion carrier (bis(2-ethylhexyl)phosphate) to NPOE, a wide range of matrix components were transferred across the SLM with no measurable transfer of the analytes. Best selectivity regarding transfer of the basic drugs and elimination of matrix components was obtained using SLM impregnated with NPOE. An optimized EME-CE-C(4)D method was used to determine the basic drugs in various samples and satisfactory analytical parameters were obtained. PMID:22835694

Kubá?, Pavel; Bo?ek, Petr

2012-12-01

89

Poly(vinylidene fluoride-co-hexafluoropropene) (PVDF-HFP) membranes for ethyl acetate removal from water.  

PubMed

In this study, poly(vinylidene fluoride-co-hexafluoropropene) (PVDF-HFP) with low crystallinity was applied as the membrane material for pervaporative separating ethyl acetate (EtAc) from its aqueous solutions. The drying conditions during membrane fabrication by means of casting the PVDF-HFP solution dominated the obtained membrane morphologies when the polar solvents such as dimethylacetamide (DMAc) and acetone were used. It was demonstrated that both the DMAc-cast and acetone-cast PVDF-HFP membranes vacuum-dried at 60 degrees C were dense but had different crystalline structures. Predominantly alpha and gamma crystalline phases were found in the acetone-cast and DMAc-cast PVDF-HFP membranes, respectively. And the different pervaporative separating performances of the two solvent-cast PVDF-HFP membranes were well explained in terms of different solution-diffusion properties which were induced from the permeants/polymer interactions on the base of the polarity differences between permeants and the two solvent-cast PVDF-HFP membranes. PMID:17884287

Tian, Xiuzhi; Jiang, Xue

2008-05-01

90

On-chip electrophoresis in supported lipid bilayer membranes achieved using low potentials.  

PubMed

A micro supported lipid bilayer (SLB) electrophoresis method was developed, which functions at low potentials and appreciable operating times. To this end, (hydroxymethyl)-ferrocene (FcCH2OH) was employed to provide an electrochemical reaction at the anode and cathode at low applied potential to avoid electrolysis of water. The addition of FcCH2OH did not alter the SLB characteristics or affect biomolecule function, and pH and temperature variations and bubble formation were eliminated. Applying potentials of 0.25-1.2 V during flow gave homogeneous electrical fields and a fast, reversible, and strong build-up of a charged dye-modified lipid in the direction of the oppositely charged electrode. Moreover, streptavidin mobility could be modulated. This method paves the way for further development of analytical devices. PMID:24345193

van Weerd, Jasper; Krabbenborg, Sven O; Eijkel, Jan; Karperien, Marcel; Huskens, Jurriaan; Jonkheijm, Pascal

2014-01-01

91

Electrophoresis of cellular membrane components creates the directional cue guiding keratocyte galvanotaxis  

PubMed Central

Summary Background Motile cells exposed to an external direct current electric field will reorient and migrate along the direction of the electric potential in a process known as galvanotaxis. The underlying physical mechanism that allows a cell to sense an electric field is unknown, although several plausible hypotheses have been proposed. In this work we evaluate the validity of each of these mechanisms. Results We find that the directional motile response of fish epidermal cells to the cathode in an electric field does not require extracellular sodium or potassium, is insensitive to membrane potential, and also insensitive to perturbation of calcium, sodium, hydrogen, or chloride ion transport across the plasma membrane. Cells migrate in the direction of applied forces from laminar fluid flow, but reversal of electroosmotic flow did not affect the galvanotactic response. Galvanotaxis fails when extracellular pH is below 6, which suggests that the effective charge of membrane components may be a crucial factor. Slowing the migration of membrane components with an increase in aqueous viscosity slows the kinetics of the galvanotactic response. In addition inhibition of PI3K reverses the cell’s response to the anode, suggesting the existence of multiple signaling pathways downstream of the galvanotactic signal. Conclusions Our results are most consistent with the hypothesis that electrophoretic redistribution of membrane components of the motile cell is the primary physical mechanism for motile cells to sense an electric field. This chemical polarization of the cellular membrane is then transduced by intracellular signaling pathways canonical to chemotaxis to dictate the cell’s direction of travel.

Allen, Greg M.; Mogilner, Alex; Theriot, Julie A.

2013-01-01

92

On-chip alternating current electrophoresis in supported lipid bilayer membranes.  

PubMed

By forming lipid bilayers within SU8 patterns, between interdigitated electrodes, we have demonstrated that it is possible to manipulate charged membrane components using low applied voltages over relatively short time scales. Two distinct patterns were studied: a nested "fish trap" which served as a molecular trap, and a diffusion aided Brownian ratchet which operated as a molecular pump. By reducing the size of the structures we have demonstrated that large applied fields (>200 V/cm) can be achieved on-chip, using low applied potentials (<13 V). By using ac fields applied orthogonal to the direction of desired motion, the molecular pumps provide a voltage independent method for moving charged components within lipid membranes over large distances. The reduced scale of the trap structures compared to those previously used in our laboratory has led to over a 10-fold decrease in the operational time require for charge build-up, from 16 h down to 1.5 h. The observed benefits of scaling means that these systems should be suitable for the on-chip separation and manipulation of charged species within supported lipid membranes. PMID:23137293

Bao, Peng; Cheetham, Matthew R; Roth, Johannes S; Blakeston, Anita C; Bushby, Richard J; Evans, Stephen D

2012-12-18

93

Functional analysis of cellulose acetate flat membranes prepared via casting technique  

Microsoft Academic Search

Cellulosic membranes reflect better utilization of renewable resources with minimum impacts on the environment. Significant market for medium pressure application is encountered in water filtration and reclamation. Thus, endeavors are needed to balance advancement of cellulose membrane and manufacturing technology modification. Cellulose membranes have been prepared via phase inversion process from different blends of polymers\\/solvents\\/additives. The casting solutions comprising polymer

S. A. Ahmed; M. H. Sorour; H. A. Talaat; S. S. Ali

2010-01-01

94

Separation of three isoenzymes of N-acetyl-?-D-hexosaminidase from human tissues by cellulose acetate membrane electrophoresis  

Microsoft Academic Search

The separation of N-acetyl-?-D-hexosaminidase isoenzymes from human tissues is used in the diagnosis and differential diagnosis of GM2 gangliosidosis, since in type 1 the A isoenzyme is deficient and in type 2 both the A and B isoenzymes are deficient. Peripheral blood leucocytes are commonly used for these investigations, and the present study demonstrates that, in addition to these two

A. Westwood; D. N. Raine

1974-01-01

95

Electrochemical sensor for 2,4-dichlorophenoxy acetic acid using molecularly imprinted polypyrrole membrane as recognition element  

Microsoft Academic Search

An electrochemical sensor based on molecularly imprinted polypyrrole membranes is reported for the determination of 2,4-dichlorophenoxy\\u000a acetic acid (2,4-D). The sensor was prepared by electropolymerization of pyrrole on a glassy carbon electrode in the presence\\u000a of 2,4-D as a template. The template was removed by overoxidation at +1.3 V in buffer solution. The sensor can effectively\\u000a improve the reductive properties of

Chenggen Xie; Shan Gao; Qingbao Guo; Ke Xu

2010-01-01

96

A novel precursor composed of polycarbosilane and palladium(II) acetate for a SiC-based gas separation membrane  

NASA Astrophysics Data System (ADS)

Organic-inorganic conversion process of a novel precursor composed of polycarbosilane and palladium(II) acetate was investigated in order to develop a SiC-based gas separation membrane. It was found that the precursor was converted to inorganic material forming Si-C-Si, Si-O-Si and Si-O-C network and evolving hydrogen, methane, ethane, carbon monoxide and carbon dioxide gases in a temperature range of 350-1000K. Furthermore, it was found that the volume shrinkage of precursor during pyrolysis process was 50%, which is 14% lower than that of PCS, because of efficient crosslinking of PCS and network formation.

Idesaki, Akira; Sugimoto, Masaki; Yoshikawa, Masahito

2011-04-01

97

Difference in Changes of Membrane Fluidity of Polymorphonuclear Leukocytes Stimulated With Phorbol Myristate Acetate and Formyl-Methionyl-Leucyl-Phenylalanine: Role of Excited Oxygen Species  

Microsoft Academic Search

Polymorphonuclear leukocytes (PMN) were stimulated with phorbol myristate acetate (PMA) and N-formyl-methionyl-leucyl phenylalanmne (FMLP) to clarify the role of excited oxygen species in inducing changes of membrane fluidity. Membrane fluidity was as- sessed by the excimer-forming lipid technique using pyrenedecanoic acid and flow cy- tometry. Membrane fluidity of PMN decreased following stimulation with PMA, and the extent of decrease was

Midori Masuda; Yutaka Komiyama; Takashi Murakami; Kenjiro Murata; Masafumi Hasui; Yoichi Hirabayashi; Yohnosuke Kobayashi

98

Net Increase of platelet membrane tyrosine specific-protein kinase activity by phorbol myristate acetate  

Microsoft Academic Search

Tyrosine protein kinase (TPK) activity in rabbit platelets after stimulation by phorbol myristate acetate (PMA) or thrombin was directly estimated by ³²P incorporation from (γ-³²)ATP into synthetic peptide angiotensin II. By PMA-treatment a net increase of TPK activity was obtained, while thrombin acted on the TPK quickly but stimulation was limited within the range attained by the control after lengthy

Noriko Ishihara; Hikaru Sakamoto; Minako Iwama; Bonro Kobayashi

1990-01-01

99

ADSORPTION AND MEMBRANE SEPARATION MEASUREMENTS WITH MIXTURES OF ETHANOL, ACETIC ACID, AND WATER  

EPA Science Inventory

Biomass fermentation produces ethanol and other renewable biofuels. Pervaporation using hydrophobic membranes is potentially a cost-effective means of removing biofuels from fermentation broths for small- to medium-scale applications. Silicalite-filled polydimethylsiloxane (PDMS)...

100

Removal of chromium from aqueous solution using cellulose acetate and sulfonated poly(ether ether ketone) blend ultrafiltration membranes.  

PubMed

A process for purifying aqueous solutions containing heavy and toxic metals such as chromium has been investigated. Chromium salts are largely used in various industries including leather-manufacturing industry. Ultrafiltration processes are largely being applied for macromolecular and heavy metal ion separation from aqueous streams. Cellulose acetate and sulfonated poly(ether ether ketone) blend ultrafiltration membranes were prepared by precipitation phase inversion technique in 100/0, 90/10, 80/20 and 70/30% polymer blend compositions and subjected to the rejection of chromium at different concentrations such as 200, 400, 600, 800 and 1000 ppm with a water-soluble macroligand (polyvinylalcohol). Factors affecting the percentage rejection and permeate flux such as pH, concentration of solute, concentration of PVA, transmembrane pressure and composition of blend membranes were investigated. It was found that percentage rejection improved at a pH 6 and a macroligand concentration of 2 wt.%. The transmembrane pressure and concentration of solute also have an effect on the separation and product rate efficiencies of the blend membranes. PMID:16860465

Arthanareeswaran, G; Thanikaivelan, P; Jaya, N; Mohan, D; Raajenthiren, M

2007-01-01

101

Permeation and Separation Characteristics of Acetic Acid?Water Mixtures Through Poly(Vinyl Alcohol)\\/Malic Acid Membranes by Evapomeation and Temperature Difference Controlled Evapomeation  

Microsoft Academic Search

The characteristics of permeation and separation of acetic acid?water mixtures through 85\\/15 (v\\/v) poly(vinyl alcohol)\\/malic acid (PVA\\/MA) membranes were investigated by evapomeation (EV) and temperature difference controlled evapomeation (TDEV) methods. The effects of permeation temperature, membrane surrounding temperature, and feed composition on the permeation rate and the separation factor were studied. The permeation rates increased but separation factors decreased with

Nuran I??klan; Oya ?anl?

2005-01-01

102

Membrane lipid dynamics in human promyelocytic leukemia cells sensitive and resistant to 12-O-tetradecanoylphorbol-13-acetate induction of differentiation  

SciTech Connect

A series of fluorescent probes was used to analyze membrane lipid dynamics in promyelocytic leukemic cells sensitive (HL-60) or resistant (R-55) to phorbol diester induction of cell differentiation. When examined with the probe 1,6-diphenyl-1,3,5-hexatriene, R-55 cells were found to have higher fluorescence anisotropy values, indicative of decreased lipid fluidity, as compared to HL-60 cells. In contrast, when HL-60 and R-55 cells were compared using a series of membrane-impermeant fluorophores that incorporate only into the outer hemileaflet of the plasma membrane, no difference was observed in membrane lipid fluidity. Exposure to 12-O-tetradecanoylphorbol-13-acetate (10 ng/ml) for 24 hr decreased the fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene in both HL-60 and R-55 cells, whereas by 48 hr only the HL-60 cells displayed the reduction. No effect on the fluorescence anisotropy of 1-(4'-trimethylammonium phenyl)-6-phenyl-1,3,5-hexatriene, which is believed to localize in the plasma membrane, was observed in R-55 cells exposed to 12-O-tetradecanoylphorbol-13-acetate (10 or 100 ng/ml), whereas HL-60 cells treated with 12-O-tetradecanoylphorbol-13-acetate (10 ng/ml) showed a marked reduction in the fluorescence anisotropy. These observations suggest that the ability of HL-60 cells to respond to 12-O-tetradecanoylphorbol-13-acetate may be affected by the physical state of the plasma membrane lipids and that the resistant phenotype is associated with decreased fluidity of either the inner leaflet of the plasma membrane and/or of the cytosolic organellar membranes.

Fisher, P.B.; Schachter, D.; Abbott, R.E.; Callaham, M.F.; Huberman, E.

1984-12-01

103

EFFECT OF METHANOL CONCENTRATION ON THE PERFORMANCE OF ASYMMETRIC CELLULOSE ACETATE REVERSE OSMOSIS MEMBRANES USING DRY\\/WET PHASE INVERSION TECHNIQUE  

Microsoft Academic Search

Asymmetric membranes were prepared from a multicomponent dope polymer so- lution consisting of cellulose acetate, acetone, formamide and methanol. In this work, the dry\\/wet phase inversion technique is used and the presence of methanol is studied. In addition, this work also presents the fundamental issues involved in altering flat sheet casting solutions to produce solutions, potentially useful for preparing hollow

ANI IDRIS; AHMAD FAUZI ISMAIL; S. ISWANDI; SIMON J. SHILTON

104

Controlled porosity osmotic pump-based controlled release systems of pseudoephedrine. I. Cellulose acetate as a semipermeable membrane.  

PubMed

A controlled porosity osmotic pump-based drug delivery system has been described in this study. Unlike the elementary osmotic pump (EOP) which consists of an osmotic core with the drug surrounded by a semipermeable membrane drilled with a delivery orifice, controlled porosity of the membrane is accomplished by the use of different channeling agents in the coating. The usual dose of pseudoephedrine is 60 mg to be taken three or four times daily. It has a short plasma half life of 5-8 h. Hence, pseudoephedrine was chosen as a model drug with an aim to develop a controlled release system for a period of 12 h. Sodium bicarbonate was used as the osmogent. The effect of different ratios of drug:osmogent on the in-vitro release was studied. Cellulose acetate (CA) was used as the semipermeable membrane. Different channeling agents tried were diethylphthalate (DEP), dibutylphthalate (DBP), dibutylsebacate (DBS) and polyethyleneglycol 400 (PEG 400). The effect of polymer loading on in-vitro drug release was studied. It was found that drug release rate increased with the amount of osmogent due to the increased water uptake, and hence increased driving force for drug release. This could be retarded by the proper choice of channeling agent in order to achieve the desired zero order release profile. Also the lag time seen with tablets coated using diethylphthalate as channeling agent was reduced by using a hydrophilic plasticizer like polyethyleneglycol 400 in combination with diethylphthalate. This system was found to deliver pseudoephedrine at a zero order rate for 12 h. The effect of pH on drug release was also studied. The optimized formulations were subjected to stability studies as per ICH guidelines at different temperature and humidity conditions. PMID:12695059

Makhija, Sapna N; Vavia, Pradeep R

2003-04-14

105

Colorful Electrophoresis  

NSDL National Science Digital Library

In this activity, learners follow step-by-step instructions to build a gel electrophoresis chamber using inexpensive materials from local hardware and electronic stores. Then, learners follow instructions to simulate DNA electrophoresis using food colors from the kitchen pantry.

Utah, University O.

2012-01-01

106

Electrophoresis-Enhanced Detection of Deoxyribonucleic Acids on a Membrane-Based Lateral Flow Strip Using Avian Influenza H5 Genetic Sequence as the Model  

PubMed Central

This study reports a simple strategy to detect a deoxyribonucleic acid (DNA) on a membrane-based lateral flow (MBLF) strip without tedious gel preparation, gel electrophoresis, and EtBr-staining processes. The method also enhances the detection signal of the genetic sample. A direct electric field was applied over two ends of the MBLF strips to induce an electrophoresis of DNAs through the strips. The signal enhancement was demonstrated by the detection of the H5 subtype of avian influenza virus (H5 AIV). This approach showed an excellent selectivity of H5 AIV from other two control species, Arabidopsis thaliana and human PSMA5. It also showed an effective signal repeatability and sensitivity over a series of analyte concentrations. Its detection limit could be enhanced, from 40 ng to 0.1 ng by applying 12 V. The nano-gold particles for the color development were labeled on the capture antibody, and UV-VIS and TEM were used to check if the labeling was successful. This detection strategy could be further developed to apply on the detection of drug-allergic genes at clinics or detection of infectious substances at incident sites by a simple manipulation with an aid of a mini-PCR machine and auxiliary kits.

Wu, Jui-Chuang; Chen, Chih-Hung; Fu, Ja-Wei; Yang, Huan-Ching

2014-01-01

107

Removal of pesticides and other micropollutants with cellulose-acetate, polyamide and ultra-low pressure reverse osmosis membranes  

Microsoft Academic Search

In 1995 several membrane manufacturers started to sell ultra low-pressure reverse osmosis membranes. The specifications of these membranes indicated that they have rejections for dissolved salts comparable to “conventional” composite (polyamide) membranes, while the required feed pressure to realize a specific production capacity is 30–40% less. This article describes the results of a preliminary study on the performance of these

J. A. M. H. Hofman; E. F. Beerendonk; H. C. Folmer; J. C. Kruithof

1997-01-01

108

Gypsum (CaSO4?2H2O) Scaling on Polybenzimidazole and Cellulose Acetate Hollow Fiber Membranes under Forward Osmosis  

PubMed Central

We have examined the gypsum (CaSO4·2H2O) scaling phenomena on membranes with different physicochemical properties in forward osmosis (FO) processes. Three hollow fiber membranes made of (1) cellulose acetate (CA), (2) polybenzimidazole (PBI)/polyethersulfone (PES) and (3) PBI-polyhedral oligomeric silsesquioxane (POSS)/polyacrylonitrile (PAN) were studied. For the first time in FO processes, we have found that surface ionic interactions dominate gypsum scaling on the membrane surface. A 70% flux reduction was observed on negatively charged CA and PBI membrane surfaces, due to strong attractive forces. The PBI membrane surface also showed a slightly positive charge at a low pH value of 3 and exhibited a 30% flux reduction. The atomic force microscopy (AFM) force measurements confirmed a strong repulsive force between gypsum and PBI at a pH value of 3. The newly developed PBI-POSS/PAN membrane had ridge morphology and a contact angle of 51.42° ± 14.85° after the addition of hydrophilic POSS nanoparticles and 3 min thermal treatment at 95 °C. Minimal scaling and an only 1.3% flux reduction were observed at a pH value of 3. Such a ridge structure may reduce scaling by not providing a locally flat surface to the crystallite at a pH value of 3; thus, gypsum would be easily washed away from the surface.

Chen, Si Cong; Su, Jincai; Fu, Feng-Jiang; Mi, Baoxia; Chung, Tai-Shung

2013-01-01

109

Gel Electrophoresis  

NSDL National Science Digital Library

This interactive activity from the Dolan DNA Learning Center illustrates the process of gel electrophoresis, in which DNA fragments are separated by size as they migrate at different rates through a gel matrix.

Foundation, Wgbh E.

2007-04-19

110

Gel Electrophoresis  

NSDL National Science Digital Library

In the early days of DNA manipulation, DNA fragments were laboriously separated by gravity. In the 1970s, the powerful tool of DNA gel electrophoresis was developed. This process uses electricity to separate DNA fragments by size as they migrate through a gel matrix. This animation from Cold Spring Harbor Laboratory's Dolan DNA Learning Center presents Gel Electrophoresis through a series of illustrations of the processes involved.

2012-01-20

111

Synthesis and Characterisation of ETS-10/Acetate-based Ionic Liquid/Chitosan Mixed Matrix Membranes for CO2/N2 Permeation.  

PubMed

Mixed matrix membranes (MMMs) were prepared by incorporating organic surfactant-free hydrothermally synthesised ETS-10 and 1-ethyl-3-methylimidazolium acetate ionic liquid (IL) to chitosan (CS) polymer matrix. The membrane material characteristics and permselectivity performance of the two-component membranes were compared with the three-component membrane and the pure CS membrane. The addition of IL increased CO2 solubility of the polymer, and, thus, the CO2 affinity was maintained for the MMMs, which can be correlated with the crystallinity, measured by FT-IR, and void fraction calculations from differences between theoretical and experimental densities. The mechanical resistance was enhanced by the ETS-10 nanoparticles, and flexibility decreased in the two-component ETS-10/CS MMMs, but the flexibility imparted by the IL remained in three-component ETS-10/IL/CS MMMs. The results of this work provide insight into another way of facing the adhesion challenge in MMMs and obtain CO2 selective MMMs from renewable or green chemistry materials. PMID:24957178

Casado-Coterillo, Clara; Del Mar López-Guerrero, María; Irabien, Angel

2014-01-01

112

Synthesis and Characterisation of ETS-10/Acetate-based Ionic Liquid/Chitosan Mixed Matrix Membranes for CO2/N2 Permeation  

PubMed Central

Mixed matrix membranes (MMMs) were prepared by incorporating organic surfactant-free hydrothermally synthesised ETS-10 and 1-ethyl-3-methylimidazolium acetate ionic liquid (IL) to chitosan (CS) polymer matrix. The membrane material characteristics and permselectivity performance of the two-component membranes were compared with the three-component membrane and the pure CS membrane. The addition of IL increased CO2 solubility of the polymer, and, thus, the CO2 affinity was maintained for the MMMs, which can be correlated with the crystallinity, measured by FT-IR, and void fraction calculations from differences between theoretical and experimental densities. The mechanical resistance was enhanced by the ETS-10 nanoparticles, and flexibility decreased in the two-component ETS-10/CS MMMs, but the flexibility imparted by the IL remained in three-component ETS-10/IL/CS MMMs. The results of this work provide insight into another way of facing the adhesion challenge in MMMs and obtain CO2 selective MMMs from renewable or green chemistry materials.

Casado-Coterillo, Clara; Lopez-Guerrero, Maria del Mar; Irabien, Angel

2014-01-01

113

Micromanipulation of adhesion of phorbol 12-myristate-13-acetate-stimulated T lymphocytes to planar membranes containing intercellular adhesion molecule-1.  

PubMed Central

This paper presents an analytical and experimental methodology to determine the physical strength of cell adhesion to a planar membrane containing one set of adhesion molecules. In particular, the T lymphocyte adhesion due to the interaction of the lymphocyte function associated molecule 1 on the surface of the cell, with its counter-receptor, intercellular adhesion molecule-1 (ICAM-1), on the planar membrane, was investigated. A micromanipulation method and mathematical analysis of cell deformation were used to determine (a) the area of conjugation between the cell and the substrate and (b) the energy that must be supplied to detach a unit area of the cell membrane from its substrate. T lymphocytes stimulated with phorbol 12-myristate-13-acetate (PMA) conjugated strongly with the planar membrane containing purified ICAM-1. The T lymphocytes attached to the planar membrane deviated occasionally from their round configuration by extending pseudopods but without changing the size of the contact area. These adherent cells were dramatically deformed and then detached when pulled away from the planar membrane by a micropipette. Detachment occurred by a gradual decrease in the radius of the contact area. The physical strength of adhesion between a PMA-stimulated T lymphocyte and a planar membrane containing 1,000 ICAM-1 molecules/micron 2 was comparable to the strength of adhesion between a cytotoxic T cell and its target cell. The comparison of the adhesive energy density, measured at constant cell shape, with the model predictions suggests that the physical strength of cell adhesion may increase significantly when the adhesion bonds in the contact area are immobilized by the actin cytoskeleton. Images FIGURE 2 FIGURE 4 FIGURE 5 FIGURE 8 FIGURE 9

Tozeren, A; Mackie, L H; Lawrence, M B; Chan, P Y; Dustin, M L; Springer, T A

1992-01-01

114

Membrane filtration of Sudan orange G on a cellulose acetate membrane filter for separation-preconcentration and spectrophotometric determination in water, chili powder, chili sauce and tomato sauce samples.  

PubMed

A simple membrane filtration procedure for separation-enrichment of Sudan orange G is presented. The method is based on the adsorption of Sudan orange G on a cellulose acetate filter and its elution from the membrane with 10 mL of ethanol. Sudan orange G in the eluent was determined by UV-visible spectrophotometry at 388 nm. The effect of analytical conditions, including pH, flow rates and eluent, sample volume, type of membrane for quantitative preconcentration and separation of Sudan orange G were examined. The influences of matrix components on Sudan orange G recoveries were studied. The preconcentration factor was 125. The detection limit was 4.9 ?g L(-1). The relative standard deviation was 4.3%. The presented procedure was applied to chili powder, chili sauce, tomato sauce, powdered beverage and water samples. PMID:22617351

ALOthman, Zeid A; Unsal, Yunus E; Habila, Mohamed; Shabaka, Azza; Tuzen, Mustafa; Soylak, Mustafa

2012-08-01

115

Electrophoresis technology  

NASA Technical Reports Server (NTRS)

A new high resolution apparatus designed for space was built as a laboratory prototype. Using a moving wall with a low zeta potential coating, the major sources of flow distortion for an electrophoretic sample stream are removed. Highly resolved fractions, however, will only be produced in space because of the sensitivity of this chamber to buoyancy-induced convection in the laboratory. The second and third flights of the McDonnell Douglas Astronautics Corporation continuous flow electrophoresis system carried samples developed at MSFC intended to evaluate the broad capabilities of free flow electrophoresis in a reduced gravity environment. Biological model materials, hemoglobin and polystyrene latex microspheres, were selected because of their past use as electrophoresis standards and as visible markers for fluid flow due to electroosmosis, spacecraft acceleration or other factors. The dependence of the separation resolution on the properties of the sample and its suspension solution was assessed.

Snyder, R. S.

1985-01-01

116

Monosaccharide and oligosaccharide analysis of proteins transferred to polyvinylidene fluoride membranes after sodium dodecyl sulfate-polyacrylamide gel electrophoresis.  

PubMed

We have developed an intermediate method toward the complete carbohydrate analysis of proteins, which should be universally applicable to all proteins and independent of sample matrix. Using only Coomassie Blue-stained proteins which have been electroblotted onto polyvinylidene fluoride membranes, we report a strategy for: (i) determining unequivocally whether a protein is glycosylated; (ii) obtaining a complete monosaccharide composition; (iii) oligosaccharide mapping which separates most forms according to size, charge and isomerity; and (iv) sequentially releasing and analyzing specific classes of oligosaccharides with endoglycosidases. The method was shown to be applicable to a variety of well characterized soluble glycoproteins and to the membrane-bound protein, the gastric H+, K(+)-ATPase. The monosaccharide composition of the H+,K(+)-ATPase revealed the absence of N-acetylneuraminic or N-glycolylneuraminic acids and a monosaccharide composition which indicated O-linked sugar chains. Oligomannosidic/hybrid and biantennary oligosaccharides were sequentially released and analyzed from one electroblotted band of recombinant tissue plasminogen activator using endo-beta-N-acetylglucosaminidase H and endo-beta-N-acetylglucosaminidase F2, respectively. Sialylated polylactosamine structures were identified and quantified by analyzing high performance liquid chromatography profiles of oligosaccharides first released by peptide-N4-(N-acetyl-beta-D-glucosaminyl)asparagine amidase and then treated with endo-beta-galactosidase, using a single, stained band of recombinant erythropoietin. This recombinant erythropoietin was found to contain eight times more tetrasialylated oligosaccharides than previously reported (Sasaki, H., Bothner, B., Dell, A., and Fukuda, M. (1987) J. Biol. Chem. 262, 12059-12076); 47% of released oligosaccharides were identified as polylactosamine structures. PMID:8444888

Weitzhandler, M; Kadlecek, D; Avdalovic, N; Forte, J G; Chow, D; Townsend, R R

1993-03-01

117

Supported liquid membrane extraction coupled in-line to commercial capillary electrophoresis for rapid determination of formate in undiluted blood samples.  

PubMed

A cheap, disposable sample pretreatment device with planar supported liquid membrane (SLM) was proposed, assembled and placed into an autosampler carousel of a commercial capillary electrophoresis (CE) instrument for automated pretreatment and analysis of formate in undiluted whole blood and serum samples. All analytical procedures except for filling the pretreatment device with donor and acceptor solutions, i.e., extraction across SLM, injection of the extracted sample and CE-UV determination of formate, were performed fully automatically. The pretreatment device required only ?L volumes of blood sample and organic solvent per extraction and was disposed off after each extraction. Good repeatability of peak areas (?7.7%) and migration times (?1.5%), linear relationship (r(2)=0.998-0.999) and limits of detection (?35?M) were achieved. The overall analytical process including blood withdrawal, filling the SLM device with respective solutions, extraction of blood sample, injection into separation capillary and CE separation of formate from other anions took less than 4min. The method was proved useful by direct determination of elevated formate concentrations in undiluted serum samples of a methanol intoxicated patient. Due to its compatibility with currently commercially available CE instrumentation, disposability of extraction devices, minimum sample handling/consumption, and short extraction/analysis times, the developed method might be attractive for rapid diagnosis of methanol poisoning in clinical and toxicological laboratories. PMID:23777836

Pant??ková, Pavla; Kubá?, Pavel; Bo?ek, Petr

2013-07-19

118

A difference gel electrophoresis study on thylakoids isolated from poplar leaves reveals a negative impact of ozone exposure on membrane proteins.  

PubMed

Populus tremula L. x P. alba L. (Populus x canescens (Aiton) Smith), clone INRA 717-1-B4, saplings were subjected to 120 ppb ozone exposure for 28 days. Chloroplasts were isolated, and the membrane proteins, solubilized using the detergent 1,2-diheptanoyl-sn-glycero-3-phosphocholine (DHPC), were analyzed in a difference gel electrophoresis (DiGE) experiment comparing control versus ozone-exposed plants. Extrinsic photosystem (PS) proteins and adenosine triphosphatase (ATPase) subunits were detected to vary in abundance. The general trend was a decrease in abundance, except for ferredoxin-NADP(+) oxidoreductase (FNR), which increased after the first 7 days of exposure. The up-regulation of FNR would increase NAPDH production for reducing power and detoxification inside and outside of the chloroplast. Later on, FNR and a number of PS and ATPase subunits decrease in abundance. This could be the result of oxidative processes on chloroplast proteins but could also be a way to down-regulate photochemical reactions in response to an inhibition in Calvin cycle activity. PMID:21520910

Bohler, Sacha; Sergeant, Kjell; Hoffmann, Lucien; Dizengremel, Pierre; Hausman, Jean-Francois; Renaut, Jenny; Jolivet, Yves

2011-07-01

119

Parallel Characterization of Anaerobic Toluene- and Ethylbenzene-Degrading Microbial Consortia by PCR-Denaturing Gradient Gel Electrophoresis, RNA-DNA Membrane Hybridization, and DNA Microarray Technology  

PubMed Central

A mesophilic toluene-degrading consortium (TDC) and an ethylbenzene-degrading consortium (EDC) were established under sulfate-reducing conditions. These consortia were first characterized by denaturing gradient gel electrophoresis (DGGE) fingerprinting of PCR-amplified 16S rRNA gene fragments, followed by sequencing. The sequences of the major bands (T-1 and E-2) belonging to TDC and EDC, respectively, were affiliated with the family Desulfobacteriaceae. Another major band from EDC (E-1) was related to an uncultured non-sulfate-reducing soil bacterium. Oligonucleotide probes specific for the 16S rRNAs of target organisms corresponding to T-1, E-1, and E-2 were designed, and hybridization conditions were optimized for two analytical formats, membrane and DNA microarray hybridization. Both formats were used to characterize the TDC and EDC, and the results of both were consistent with DGGE analysis. In order to assess the utility of the microarray format for analysis of environmental samples, oil-contaminated sediments from the coast of Kuwait were analyzed. The DNA microarray successfully detected bacterial nucleic acids from these samples, but probes targeting specific groups of sulfate-reducing bacteria did not give positive signals. The results of this study demonstrate the limitations and the potential utility of DNA microarrays for microbial community analysis.

Koizumi, Yoshikazu; Kelly, John J.; Nakagawa, Tatsunori; Urakawa, Hidetoshi; El-Fantroussi, Said; Al-Muzaini, Saleh; Fukui, Manabu; Urushigawa, Yoshikuni; Stahl, David A.

2002-01-01

120

Role of bis(monoacylglycero)phosphate in propranolol binding to phospholipid membranes under acidic conditions as measured by high-performance frontal analysis/capillary electrophoresis.  

PubMed

Bis(monoacylglycero)phosphate (BMP) is localized in acidic organelles such as late endosomes or lysosomes. It has been reported that BMP levels increase under phospholipidosis induced by cationic amphiphilic drugs. In the present study, the effect of BMP on the binding of propranolol (PRO) to phospholipid liposomes under acidic conditions was investigated. Binding experiments were conducted by high-performance frontal analysis/capillary electrophoresis. PRO showed nonspecific binding to BMP-containing liposomes (BMP:phosphatidylcholine = 1:4), when numbers of bound drug molecules per lipid molecule (r) ranged 0.01-0.06. Total binding affinity increased depending on the BMP content. Binding affinity was decreased by low ionic strength, or by substitution of BMP with diacylglycerol, suggesting that electrostatic interactions were involved. The binding-enhancement effect of BMP was almost equivalent to that of phosphatidylglycerol, and slightly larger than that of phosphatidylserine. An acidic environment (pH 5.0) decreased total binding affinity to BMP-containing liposomes. This could be explained by the pH-partition theory (i.e., the loss in affinity was caused by a decrease in the neutral form of the drug accessible to the membrane core). These results suggest that PRO binding is enhanced by BMP in late endosomes or lysosomes, whereas an acidic environment weakens such binding. PMID:22996699

Hamaguchi, Ryohei; Kuroda, Yukihiro; Tanimoto, Toshiko; Haginaka, Jun

2012-10-01

121

Characterization of a direct effect of phorbol myristate acetate on human neutrophil cell membrane using 31D8 monoclonal antibody  

Microsoft Academic Search

We found that 4-13-phorbol 12-myristate 13-acetate (PMA) caused decreased expression of the polymorphonuclear neutrophil (PMN) surface antigen 31D8. In contrast to the rapid initiation of the oxidative burst caused by PMA, the effect was slow to start but in- creased during incubation periods up to 50 mm. To study this apparent protein kinase C-independent late effect of PMA, we measured

Charles L. Woronick; Eufronio G. MaderazotS; Monique N. AnthonyPeter; J. Krause; Ramadan I. Sha

122

Gel Electrophoresis  

NSDL National Science Digital Library

In this activity, learners simulate the process of DNA fingerprinting by using electricity to separate colored dyes. Learners use simple materials to assemble a comb (electrophoresis chamber) to hold the samples, make a 0.2% sodium bicarbonate buffer and 1% gel solution, connect a high voltage power supply, and prepare 5 different samples. Then learners test their model and observe each sample.

Yu, Julie

2007-01-01

123

Molecular imprinting of cellulose acetate-sulfonated polysulfone blend membranes for Rhodamine B by phase inversion technique  

Microsoft Academic Search

A functional polymer, sulfonated polysulfone (SPS) with a degree of substitution of 0.10, was prepared and then blended with cellulose diacetate (CA) as the matrix polymer for the preparation of molecularly imprinted polymer (MIP) membranes via phase inversion from a casting solution containing a template. Polyethylene glycol was found to be compatible with these polymers and was subsequently used as

Malaisamy Ramamoorthy; Mathias Ulbricht

2003-01-01

124

Calcium movement and membrane potential changes in the early phase of neutrophil activation by phorbol myristate acetate: a study with ion- selective electrodes  

PubMed Central

To quantitate calcium movements and membrane potential changes in stimulated neutrophils, we have measured net fluxes of Ca2+ and of the lipophilic cation tetraphenyl phosphonium by a very sensitive ion- selective electrode system. Activation of neutrophils by 3 X 10(-8) M phorbol 12-myristate, 13-acetate induces a release of approximately 20% of total cell calcium, with an initial lag period of less than 10 s. The Ca2+ outflux is markedly reduced in ATP-depleted cells and in the presence of a calmodulin inhibitor, thereby suggesting that it occurs by activation of the ATP-driven Ca2+ pump of the neutrophil plasmalemma. Activation of neutrophils also induces a transiently increased exchange of medium 45Ca with cell calcium, which is measurable a few seconds after cell exposure to the stimulant and peaks at approximately 40 s. Stimulation of neutrophils after attainment of steady-state accumulation of tetraphenyl phosphonium (resting potential of -67 mV) results in a marked depolarization, with a lag period of approximately 60 s. The rate and extent of depolarization are reduced by 40 and 65%, respectively, in a low Na+ medium but are not modified by an inhibitor of anion exchange across membranes. A high-K+ medium depolarizes neutrophils without either modifying their resting oxidative metabolism or impairing stimulability by the phorbol ester. Phorbol 12-myristate, which also exhibits no effect on the oxidative metabolism of neutrophils, does not induce Ca2+ extrusion and membrane potential changes. The causal relationship between Ca2+ mobilization, membrane potential changes and activation of neutrophil functions is discussed.

1982-01-01

125

Characterisation of the effects of anthranilic and (indanyloxy) acetic acid derivatives on chloride transport in membrane vesicles.  

PubMed

The effects of the Cl- channel blockers, NPPB, IAA94/95 and a number of related compounds on 36Cl- transport in membrane vesicles from bovine kidney cortex and rabbit ileum mucosa brush borders have been studied. These vesicles have been previously shown to be enriched in Cl- channel and Cl-/anion cotransport activity, respectively. Chloride transport was assayed in both types of vesicles by measuring the uptake of 36Cl- in response to an outwardly-directed Cl- concentration gradient. In kidney microsomes, a large proportion of the observed 36Cl- uptake was mediated by an electrogenic uniport and could be substantially reduced by clamping the membrane potential at zero mV using K+ and valinomycin. Chloride uptake was inhibited by both NPPB and IAA94/95 with apparent IC50 values of around 10 microM under optimal conditions (i.e., 4 min uptake at 4 degrees C). Under other conditions (e.g., 10 min uptake at 25 degrees C), where uptake had reached a steady-state level, much higher concentrations of inhibitor were required to cause inhibition. Therefore, previous differences in the reported potency of these compounds may, in part, have been due to the conditions under which Cl- uptake was measured. In addition, both NPPB and, to a lesser extent, IAA94/95 were found to have other effects on the vesicles, in that, when added at a concentration of 100 microM, they induced a leakage of pre-accumulated 36Cl-. This was probably caused by either dissipation of membrane potential or damage to the vesicle membranes. The sulphonic acid derivatives of NPPB and IAA94/95 (NPPB-S and ISA94/95, respectively) blocked 36Cl- uptake with around the same potency as NPPB and IAA94/95, but did not cause any non-specific Cl- leakage, when added at concentrations up to 100 microM. Inhibition of 36Cl- uptake by all four compounds was almost completely reversible. However, when vesicles were incubated with the inhibitors in the presence of an outward Cl- concentration gradient, or if vesicles were freeze/thawed in the presence of the compounds, inhibition could be only partially reversed. In rabbit brush border membrane vesicles, 36Cl- uptake was not reduced when the vesicles were voltage clamped using valinomycin and K+, and was therefore probably mediated by Cl-/Cl- exchange. However, despite the lack of effect of valinomycin, 36Cl- uptake was inhibited by both NPPB (approx. 80% inhibition at 100 microM) and, to a lesser extent, by IAA94/95 (approx. 30% inhibition at 100 microM).(ABSTRACT TRUNCATED AT 400 WORDS) PMID:1651113

Pope, A J; Richardson, S K; Ife, R J; Keeling, D J

1991-08-01

126

Characterization of Clluloseetate butyrate Membranes.  

National Technical Information Service (NTIS)

Three major areas of interest were investigated. These included the characterization of cellulose acetate butyrate membranes, the optimization of cellulose acetate butyrate membranes, the optimization of butyrate membrane performance and the production of...

S. Mankikian M. I. Foley C. M. Wong W. S. Gillam H. E. Podall

1970-01-01

127

Fluid flow electrophoresis in space  

NASA Technical Reports Server (NTRS)

Four areas relating to free-flow electrophoresis in space were investigated. The first was the degree of improvement over earthbound operations that might be expected. The second area of investigation covered the problems in developing a flowing buffer electrophoresis apparatus. The third area of investigation was the problem of testing on the ground equipment designed for use in space. The fourth area of investigation was the improvement to be expected in space for purification of biologicals. The results of some ground-based experiments are described. Other studies included cooling requirements in space, fluid sealing techniques, and measurement of voltage drop across membranes.

Griffin, R. N.

1975-01-01

128

Abiraterone acetate.  

PubMed

Abiraterone acetate (CB 7630; CB7630; JNJ-212082), the 3?-acetate prodrug of abiraterone, is structurally related to ketoconazole and is being developed by Cougar Biotechnology as a hormonal therapy for advanced prostate and breast cancers. As a selective inhibitor of adrenal androgens, it is thought to be a safer product than existing second-line hormonal therapies. This review discusses the key development milestones and therapeutic trials of this drug. PMID:21171672

2010-01-01

129

Electrophoresis device  

NASA Technical Reports Server (NTRS)

A device for separating cellular particles of a sample substance into fractionated streams of different cellular species includes a casing having a distribution chamber, a separation chamber, and a collection chamber. The electrode chambers are separated from the separation chamber interior by means of passages such that flow variations and membrane variations around the slotted portion of the electrode chamber do not enduce flow perturbations into the laminar buffer curtain flowing in the separation chamber. The cellular particles of the sample are separated under the influence of the electrical field and the separation chamber into streams of different cellular species. The streams of separated cells enter a partition array in the collection chamber where they are fractionated and collected.

Rhodes, P. H.; Snyder, R. S. (inventors)

1982-01-01

130

Parallel Characterization of Anaerobic Toluene and Ethylbenzene-Degrading Microbial Consortia by PCR-Denaturing Gradient Gel Electrophoresis, RNA-DNA Membrane Hybridization, and DNA Microarray Technology  

Microsoft Academic Search

A mesophilic toluene-degrading consortium (TDC) and an ethylbenzene-degrading consortium (EDC) were established under sulfate-reducing conditions. These consortia were first characterized by denaturing gradient gel electrophoresis (DGGE) fingerprinting of PCR-amplified 16S rRNA gene fragments, followed by sequenc- ing. The sequences of the major bands (T-1 and E-2) belonging to TDC and EDC, respectively, were affiliated with the family Desulfobacteriaceae. Another major

Yoshikazu Koizumi; John J. Kelly; Tatsunori Nakagawa; Hidetoshi Urakawa; Saïd El-Fantroussi; Saleh Al-Muzaini; Manabu Fukui; Yoshikuni Urushigawa; David A. Stahl

2002-01-01

131

Separation of plant membranes by electromigration techniques  

Microsoft Academic Search

The review focuses on the multiple separating regimes that offers the free flow electrophoresis technique: free flow zone electrophoresis, isoelectric focusing, isotachophoresis, free flow step electrophoresis. Also, the feasibility to apply either interval or continuous flow electrophoresis is evaluated. The free flow zone electrophoresis regime is generally selected for the separation of cells, organelles and membranes while the other regimes

Hervé Canut; Johann Bauer; Gerhard Weber

1999-01-01

132

Kidney cell electrophoresis  

NASA Technical Reports Server (NTRS)

A kidney cell electrophoresis technique is described in four parts: (1) the development and testing of electrophoresis solutions; (2) optimization of freezing and thawing; (3) procedures for evaluation of separated kidney cells; and (4) electrophoretic mobility characteristics of kidney cells.

Todd, P.

1979-01-01

133

Protein electrophoresis - serum  

MedlinePLUS

This lab test measures the types of protein in the fluid (serum) part of a blood sample. Other electrophoresis tests that measure proteins in the serum include: Immunoelectrophoresis Immunofixation Globulin electrophoresis

134

An Economical Electrophoresis Apparatus  

ERIC Educational Resources Information Center

Describes the production of an electrophoresis apparatus from commonly discarded articles. Outlines paper and gel electrophoresis and its application to the separation of amino acids and intestinal enzymes. (GS)

Andrews, I. M.

1975-01-01

135

Capillary Electrophoresis of Proteins  

Microsoft Academic Search

1.1. Capillary Electrophoresis of Proteins Capillary electrophoresis (CE) is a separation technique that combines aspects of both gel electrophoresis and high performance liquid chromatography (HPLC). As is the case for gel electrophoresis, the separation in CE is based upon differential migration in an electrical field. Like HPLC, the detection of the migrating sample analytes may be monitored on-line or postcolumn\\/capillary

Mark Strege

136

A 9-vinyladenine-based molecularly imprinted polymeric membrane for the efficient recognition of plant hormone 1H-indole-3-acetic acid  

Microsoft Academic Search

9-Vinyladenine was synthesized as a novel functional monomer for molecular imprinting techniques and its structure was established with elemental analysis and 1H NMR spectroscopy. The binding mechanism between this functional monomer 9-vinyladenine and the plant hormone 1H-indole-3-acetic acid in acetonitrile was studied with UV–vis spectrophotometry. Based on this study, using 1H-indole-3-acetic acid as a template molecule, a specific 9-vinyladenine-based molecularly

Changbao Chen; Yanjun Chen; Jie Zhou; Chunhui Wu

2006-01-01

137

Variation within serovars of Neisseria gonorrhoeae detected by structural analysis of outer-membrane protein PIB and by pulsed-field gel electrophoresis  

Microsoft Academic Search

Outer-membrane protein PI is the antigen responsible for serovar specificity of Neisseria gonorrhoeae and is a potential vaccine target. In order to investigate possible hidden variation within a serovar, the sequence of the por genes encoding protein PIB have been obtained from a series of strains, including isolates known to be epidemiologically linked. The inferred amino acid sequences of the

Susan J. Cooke; C. La Poh; C. A. Ison; J. E. Heckels

1997-01-01

138

A comparative study of the sorption of serum albumin, lysozyme, and cytochrome C at phospholipid membranes using surface tensiometry, electrophoresis, and leakage of probe molecules  

Microsoft Academic Search

Protein sorption at phospholipid membranes is studied when proteins are injected into the solution, by measuring the change in the surface tension of lipid monolayers spread on the water surface. A method for analyzing the surface tension data is proposed. The results of this analysis are in agreement with the results of experiments on liposomes: an investigation of the change

Hideo Matsumura; Mariana Dimitrova

1996-01-01

139

Electrokinetic injection across supported liquid membranes: new sample pretreatment technique for online coupling to capillary electrophoresis. Direct analysis of perchlorate in biological samples.  

PubMed

A simple and sensitive method for quantifying perchlorate in biological samples using CE and capacitively coupled contactless conductivity detection was developed. An online combination of a supported liquid membrane, an inert polypropylene membrane impregnated with 1-hexanol, and electrokinetic injection of perchlorate across the supported liquid membrane directly into the separation capillary reduced the need for laborious sample pretreatment procedures, resulting in a cheap and rapid method with low LODs capability. Baseline separation of perchlorate and other anions in biological samples was achieved in background electrolyte solution consisting of 15 mM nicotinic acid and 1 mM 3-(N,N-dimethylmyristylammonio)propanesulfonate at pH 3.3. The analytical method showed excellent parameters in terms of reproducibility; RSD values for peak areas and corrected migration times at a spiked concentration of 100 ?g/L of perchlorate were below 10 and 0.4%, respectively. Linear calibration curves were obtained for perchlorate in the concentration range 10-1000 ?g/L (r(2) >0.999) with LODs between 2 and 5 ?g/L for human urine, breast milk, serum, cow's milk, and red wine. Recoveries at 25 ?g/L of perchlorate were between 97 and 106% for all biological samples. The low LODs rivaling those of presently used analytical methods support the use of this method for quantification of perchlorate in biological samples in the future. PMID:22965714

Kubá?, Pavel; Kiplagat, Isaac K; Bo?ek, Petr

2012-09-01

140

Kidney cell electrophoresis  

NASA Technical Reports Server (NTRS)

Materials and procedures for microgravity electrophoresis of living human embryonic kidney cells were evaluated, ground support in the form of analytical cell electrophoresis and flow cytometry was provided and cells returned from space flight were analyzed. Preflight culture media, electrophoresis buffer, fraction collection media, temperature profiles, and urokinase assay procedures were tested prior to flight. Electrophoretic mobility distributions of aliquots of the cell population to be fractionated in flight were obtained. The protocol established and utilized is given.

Todd, P.

1985-01-01

141

Isolation of glycosaminoglycans (heparan sulfate) from glomerular basement membranes  

PubMed Central

Glycosaminoglycans were isolated from purified fractions of glomerular basement membranes and partially characterized by chemical analysis and cellulose acetate electrophoresis. Basement membranes were prepared by detergent treatment of rat glomeruli and subjected to digestion with papain and Pronase. Glycosaminoglycans were isolated from the digests by precipitation with cetyl pyridinium chloride and ethanol. Results of cellulose acetate electrophoresis of the isolated glycosaminoglycan fraction revealed the presence of one major and one minor spot. The major spot was identified as heparan sulfate because it comigrated with the heparan sulfate standard and was sensitive to heparinase and to nitrous acid oxidation but insensitive to chondroitinase ABC and to testicular or leech hyaluronidase. The minor spot was tentatively identified as hyaluronic acid based on its migratory behavior and sensitivity to leech and testicular hyaluronidase. The chemical composition of the isolated glycosaminoglycan was typical of that of heparan sulfate (high carbazole/orcinol ratio, high sulfate content, absence of galactosamine). The data support and confirm the cytochemical data obtained previously [Kanwar, Y. S. & Farquhar, M. G. (1979) Proc. Natl. Acad. Sci. USA 76, 1303-1307] demonstrating that heparan sulfate is the only sulfated glycosaminoglycan detectable in the glomerular basement membrane. The present results suggest that in addition to sulfated glycosaminoglycan some nonsulfated glycosaminoglycan (hyaluronic acid) may also be present in the glomerular basement membrane. Images

Kanwar, Yashpal S.; Farquhar, Marilyn Gist

1979-01-01

142

Electrophoresis of biological materials  

NASA Technical Reports Server (NTRS)

The selection of biological products was studied for electrophoresis in space. Free flow electrophoresis, isoelectric focusing, and isotachophoresis are described. The candidates discussed include: immunoglobulins and gamma globulins; isolated islet of langerhans from pancreas; bone marrow; tumor cells; kidney cells, cryoprecipitate; and column separated cultures.

1975-01-01

143

Automatic multiple applicator electrophoresis  

NASA Technical Reports Server (NTRS)

Easy-to-use, economical device permits electrophoresis on all known supporting media. System includes automatic multiple-sample applicator, sample holder, and electrophoresis apparatus. System has potential applicability to fields of taxonomy, immunology, and genetics. Apparatus is also used for electrofocusing.

Grunbaum, B. W.

1977-01-01

144

Electrophoresis experiments for space  

NASA Astrophysics Data System (ADS)

It has long been hoped that space could alleviate the problems of large-scale, high-capacity electrophoresis. Support media and reduced chamber dimensions of capillary electrophoresis have established the physical boundaries for Earth-based systems. Ideally, electrophoresis conducted in a virtual weightless environment in an unrestricted ``free'' fluid should have great potential. The electrophoresis and isoelectric focusing experiments done in the reduced gravity over the past twenty-five years have demonstrated the absence of thermal convection and sedimentation as well as the presence of electrohydrodynamics that requires careful control. One commercial venture produced gram amounts of an electrophoretically purified protein during seven Space Shuttle flights but the market disappeared in the six years between experiment conception and performance on the Space Shuttle. Our accumulated experience in microgravity plus theoretical models predict improvements that should be possible with electrophoresis if past problems are considered and both invention of new technologies and innovation of procedures on the Space Station are encouraged. .

Snyder, Robert S.; Rhodes, Percy H.

2000-01-01

145

Synthesis and characterization of cellulose acetate-polysulfone blend microfiltration membrane for separation of microbial cells from lactic acid fermentation broth  

Microsoft Academic Search

This work is focused on synthesis and characterization of a polymer blend microfiltration membrane for separation of microbial cells from lactic acid fermentation broth in a continuous process. The membranes were prepared by blending hydrophilic cellulose diacetate (CA) polymer with hydrophobic polysulfone (PSF) polymer in wet phase inversion method. Polymers were blended in N-methyl-2-pyrrolidone (NMP) solvent (70wt.%) where polyethylene glycol

J. Sikder; C. Pereira; S. Palchoudhury; K. Vohra; D. Basumatary; P. Pal

2009-01-01

146

Demonstration of calcium-dependent phospholipase A2 activity in membrane preparation of rabbit neutrophils. Absence of activation by fMet-Leu-Phe, phorbol 12-myristate 13-acetate and A-kinase.  

PubMed Central

The presence of a phospholipase A2 (PLA2) activity in rabbit neutrophil membrane preparation that is able to release [1-14C]oleic acid from labelled Escherichia coli has been demonstrated. The activity is critically dependent on the free calcium concentration and marginally stimulated by GTP gamma S. More than 80% of maximal activity is reached at 10 microM-Ca2+. The chemotactic factor, fMet-Leu-Phe, does not stimulate the PLA2 activity in this membrane preparation. Pretreatment of the membrane preparation, under various experimental conditions, or intact cells, before isolation of the membrane with phorbol 12-myristate 13-acetate (PMA), does not affect PLA2 activity. Addition of the catalytic unit of cyclic AMP-dependent kinase to membrane preparation has no effect on PLA2 activity. Pretreatment of the intact neutrophil with dibutyryl-cAMP before isolation of the membrane produces a small but consistent increase in PLA2 activity. The activity of PLA2 in membrane isolated from cells treated with the protein kinase inhibitor 1-(5-isoquinolinesulphonyl)-2-methyl piperazine dihydrochloride (H-7) is significantly decreased. Furthermore, although the addition of PMA to intact rabbit neutrophils has no effect on the release of [3H]arachidonic acid from prelabelled cells, it potentiates significantly the release produced by the calcium ionophore A23187. This potentiation is not due to an inhibition of the acyltransferase activity. H-7 inhibits the basal release of arachidonic acid but does not inhibit the potentiation by PMA. These results suggest several points. (1) fMet-Leu-Phe does not stimulate PLA2 directly, and its ability to release arachidonic acid in intact neutrophils is mediated through its action on phospholipase C. (2) The potentiating effect of PMA on A23187-induced arachidonic acid release is most likely due to PMA affecting either the environment of PLA2 and/or altering the organization of membrane phospholipids in such a way as to increase their susceptibility to hydrolysis. (3) The intracellular level of cyclic AMP probably does not directly affect the activity of PLA2.

Matsumoto, T; Tao, W; Sha'afi, R I

1988-01-01

147

Binary Oscillatory Crossflow Electrophoresis  

NASA Technical Reports Server (NTRS)

We present preliminary results of our implementation of a novel electrophoresis separation technique: Binary Oscillatory Cross flow Electrophoresis (BOCE). The technique utilizes the interaction of two driving forces, an oscillatory electric field and an oscillatory shear flow, to create an active binary filter for the separation of charged species. Analytical and numerical studies have indicated that this technique is capable of separating proteins with electrophoretic mobilities differing by less than 10%. With an experimental device containing a separation chamber 20 cm long, 5 cm wide, and 1 mm thick, an order of magnitude increase in throughput over commercially available electrophoresis devices is theoretically possible.

Molloy, Richard F.; Gallagher, Christopher T.; Leighton, David T., Jr.

1996-01-01

148

Preparative electrophoresis experiment design  

NASA Technical Reports Server (NTRS)

A multifaceted study supporting the NASA programs to develop a space electrophoresis capability has been conducted. The study involved principally the technique of continuous free electrophoresis. It comprised a critical review of the art, study of new techniques for enhancing resolution and stability, and construction and initial testing of a high resolution cell. The effort resulted in a significant advance in free electrophoresis technique. It has provided also a much improved base for developments exploiting the added advantages of a zero-gravity environment.

Thiehler, A.

1972-01-01

149

Measuring Genetic Variation in Zebra Mussels Using Acetate Electrophoresis  

NSDL National Science Digital Library

This resource is a mini-workshop for instructing a laboratory exercise in genetics and evolutionary biology. Students learn concepts of genetic variability and equilibria in natural populations. This resource can be used to organize laboratory exercises for classes in genetics and evolutionary biology.

Corey A Goldman (University of Toronto;)

1998-01-01

150

Electrophoresis operations in space  

NASA Technical Reports Server (NTRS)

Application of electrophoresis in space processing is described. Spaceborne experiments in areas such as biological products and FDA approved drugs are discussed. These experiments will be carried on shuttle payloads.

Richman, D. W.

1982-01-01

151

Electrophoresis and Gel Analysis  

NSDL National Science Digital Library

In this animation produced by WGBH and Digizyme, Inc., see how molecules of DNA are separated using gel electrophoresis, and how this process enables scientists to compare the molecular variations of two or more DNA samples.

Foundation, Wgbh E.

2011-09-22

152

Effect of phorbol myristate acetate on secretion of parathyroid hormone  

SciTech Connect

The influence of phorbol myristate acetate (PMA), an activator of protein kinase c, on the secretion of parathyroid hormone from collagenase-dispersed bovine parathyroid cells was tested. The cells were incubated at low or high concentrations of calcium in the medium, and the hormone secreted into the medium was measured by a radioimmunoassay that recognizes both intact and C-terminal fragments of hormone. A stimulatory effect of PMA at high calcium, seen at PMA concentrations as low as 1.6 nM, did not occur with a biologically inactive 4{alpha}-isomer of phorbol ester, and was independent of changes in cellular adenosine 3{prime},5{prime}-cyclic monophosphate levels. Examination of {sup 32}P-labeled phosphoproteins by two-dimensional gel electrophoresis revealed acidic proteins of {approximately}20,000 and 100,000 Da that were phosphorylated at low and high calcium + 1.6 {mu}M PMA but not at high calcium alone. The protein kinase c activity associated with the membrane fraction of parathyroid cells significantly decreased 40% when the cells were incubated at high vs. low calcium. The data suggest that calcium may regulate parathyroid hormone secretion through changes in protein kinase c activity of the membrane fraction of the cell and protein phosphorylation.

Morrissey, J.J. (Washington Univ. School of Medicine, St. Louis, MO (USA))

1988-01-01

153

Recent advances in preparative electrophoresis  

NASA Technical Reports Server (NTRS)

Various approaches for preparative electrophoresis, and three new instruments for preparative electrophoresis are discussed. Consideration is given to isoelectric focusing, isotachophoresis, and zone electrophoresis, three gel-based electrophoresis methods. The design, functions, and performance of the Elphor VaP 21 device of Hannig (1982), the shear-stabilized BIOSTREAM separator of Thompson (1983), and the recycling isoelectric focusing device are described.

Mosher, Richard A.; Thormann, Wolfgang; Egen, Ned B.; Couasnon, Pascal; Sammons, David W.

1987-01-01

154

Glycosaminoglycan blotting on nitrocellulose membranes treated with cetylpyridinium chloride after agarose-gel electrophoretic separation.  

PubMed

We describe a method for blotting and immobilizing several nonsulfated and sulfated complex polysaccharides on membranes made hydrophilic and positively charged by a cationic detergent after their separation by conventional agarose gel electrophoresis. Nitrocellulose membranes were derivatized with the cationic detergent cetylpyridinium chloride (CPC) and mixtures of glycosaminoglycans (GAGs) were capillary-blotted after their separation in agarose gel electrophoresis in barium acetate/1,2-diaminopropane. Single purified species of variously sulfated polysaccharides were transferred onto the derivatized membranes after electrophoresis with an efficiency of 100% and stained with alcian blue (irreversible staining) and toluidine blue (reversible staining) permitting about 0.1 nug threshold of detection. Nonsulfated polyanions, hyaluronic acid, a fructose-containing polysaccharide with a chondroitin backbone purified from Escherichia coli U1-41, and its defructosylated product, were also electrophoretically separated and transferred onto membranes. The limit of detection for desulfated GAGs was about 0.1-0.5 nug after irreversible or reversible staining. GAG extracts from bovine, lung and aorta, and human aorta and urine were separated by agarose gel electrophoresis and blotted on CPC-treated nitrocellulose membranes. The polysaccharide composition of these extracts was determined. The membrane stained with toluidine blue (reversible staining) was destained and the same lanes used for immunological detection or other applications. Reversible staining was also applied to recover single species of polysaccharides after electrophoretic separation of mixtures of GAGs and their transfer onto membranes. Single bands were released from the membrane with an efficiency of 70-100% for further biochemical characterization. PMID:12373753

Maccari, Francesca; Volpi, Nicola

2002-09-01

155

Capillary electrophoresis-mass spectrometry of carbohydrates  

PubMed Central

The development of methods for capillary electrophoresis (CE) with on-line mass spectrometric detection (CE/MS) is driven by the need for accurate, robust and sensitive glycomics analysis for basic biomedicine, biomarker discovery, and analysis of recombinant protein therapeutics. One important capability is to profile glycan mixtures with respect to the patterns of substituents including sialic acids, acetate, sulfate, phosphate, and other groups. There is additional need for an MS-compatible separation system capable of resolving carbohydrate isomers. This review summarizes applications of CS/MS to analysis of carbohydrates, glycoproteins and glycopeptides that have appeared since 2008. Readers are referred to recent comprehensive reviews covering earlier publications.

Zaia, Joseph

2014-01-01

156

[Transparency of analytical results found by different methods of electrophoresis studies on casein (author's transl)].  

PubMed

The electrophoretic mobility of the major casein components has been studied on different carriers. Besides free electrophoresis and paper electrophoresis starch gel, polyacrylamide gel and cellulose acetate gel have compared. With urea buffer mixtures of neutral to alkaline pH a mobility scale on all gels was found corresponding the order alphas-, beta-, kappa-, gamma-casein in the sense of decreasing mobility. The application of commercially available cellulose acetate strips for the investigation of genetic material in large numbers has been found to be sufficient. The transparency of polyacrylamide gel, starch gel and cellulose acetate gel results is guaranteed. PMID:7057

Kirchmeier, O

1975-04-01

157

Electrophoresis in space.  

PubMed

Programs for free flow electrophoresis in microgravity over the past 25 years are reviewed. Several studies accomplished during 20 spaceflight missions have demonstrated that sample throughput is significantly higher in microgravity than on the ground. Some studies have shown that resolution is also increased. However, many cell separation trials have fallen victim to difficulties associated with experimenting in the microgravity environment such as microbial contamination, air bubbles in electrophoresis chambers, and inadequate facilities for maintaining cells before and after separation. Recent studies suggest that the charge density of cells at their surface may also be modified in microgravity. If this result is confirmed, a further cellular mechanism of "sensing" the low gravity environment will have been found. Several free fluid electrophoresis devices are now available. Most have been tried at least once in microgravity. Newer units not yet tested in spaceflight have been designed to accommodate problems associated with space processing. The USCEPS device and the Japanese FFEU device are specifically designed for sterile operations, whereas the Octopus device is designed to reduce electroosmotic and electrohydrodynamic effects, which become dominant and detrimental in microgravity. Some of these devices will also separate proteins by zone electrophoresis, isotachophoresis, or isoelectric focusing in a single unit. Separation experiments with standard test particles are useful and necessary for testing and optimizing new space hardware. A cohesive free fluid electrophoresis program in the future will obviously require (1) flight opportunities and funding, (2) identification of suitable cellular and macromolecular candidate samples, and (3) provision of a proper interface of electrophoresis processing equipment with biotechnological facilities--equipment like bioreactors and protein crystal growth chambers. The authors feel that such capabilities will lead to the production of commercially useful quantities of target products and to an accumulation of new knowledge relating to the complexities of electrostatic phenomena at the cell surface. PMID:10660776

Bauer, J; Hymer, W C; Morrison, D R; Kobayashi, H; Seaman, G V; Weber, G

1999-01-01

158

Gel Electrophoresis of Dyes  

NSDL National Science Digital Library

In this experiment related to plant biotechnology, learners discover how to prepare and load an electrophoresis gel. They will then run the gels in an electrophoresis system to separate several dyes that are of different molecular sizes and carry different charges. This technique is fundamental to many of the procedures used in biotechnology. This lesson guide includes background information for the educator, safety precautions, and questions with answers for learners. For safety reasons, adult supervision is recommended. Modifications for use with younger learners are described in a related PDF (see related resource).

Stephens, Janice; Leach, Jan

2011-01-01

159

Automatic multiple-sample applicator and electrophoresis apparatus  

NASA Technical Reports Server (NTRS)

An apparatus for performing electrophoresis and a multiple-sample applicator is described. Electrophoresis is a physical process in which electrically charged molecules and colloidal particles, upon the application of a dc current, migrate along a gel or a membrane that is wetted with an electrolyte. A multiple-sample applicator is provided which coacts with a novel tank cover to permit an operator either to depress a single button, thus causing multiple samples to be deposited on the gel or on the membrane simultaneously, or to depress one or more sample applicators separately by means of a separate button for each applicator.

Grunbaum, B. W. (inventor)

1977-01-01

160

Pallidol hexa-acetate ethyl acetate monosolvate  

PubMed Central

The entire mol­ecule of pallidol hexa­acetate {systematic name: (±)-(4bR,5R,9bR,10R)-5,10-bis­[4-(acet­yloxy)phen­yl]-4b,5,9b,10-tetra­hydro­indeno­[2,1-a]indene-1,3,6,8-tetrayl tetra­acetate} is completed by the application of twofold rotational symmetry in the title ethyl acetate solvate, C40H34O12·C4H8O2. The ethyl acetate mol­ecule was highly disordered and was treated with the SQUEEZE routine [Spek (2009 ?). Acta Cryst. D65, 148–155]; the crystallographic data take into account the presence of the solvent. In pallidol hexa­acetate, the dihedral angle between the fused five-membered rings (r.m.s. deviation = 0.100?Å) is 54.73?(6)°, indicating a significant fold in the mol­ecule. Significant twists between residues are also evident as seen in the dihedral angle of 80.70?(5)° between the five-membered ring and the pendent benzene ring to which it is attached. Similarly, the acetate residues are twisted with respect to the benzene ring to which they are attached [C—O(carb­oxy)—C—C torsion angles = ?70.24?(14), ?114.43?(10) and ?72.54?(13)°]. In the crystal, a three-dimensional architecture is sustained by C—H?O inter­actions which encompass channels in which the disordered ethyl acetate mol­ecules reside.

Mao, Qinyong; Taylor, Dennis K.; Ng, Seik Weng; Tiekink, Edward R. T.

2013-01-01

161

Isolation and Characterization of the Outer Membrane of Neisseria gonorrhoeae  

PubMed Central

The cell envelope of Neisseria gonorrhoeae strain 2686, colonial type 4, was isolated from spheroplasts formed by the action of ethylenediaminetetraacetic acid and lysozyme. Isopycnic centrifugation of osmotically ruptured spheroplasts resolved the cell envelope into two main membrane fractions. Chemical and enzymatic analyses were used to characterize these isolated membranes. Succinic dehydrogenase, reduced nicotinamide adenine dinucleotide oxidase, and d-lactate dehydrogenase were localized in the membrane fraction of buoyant density, ?° = 1.141 g/cm3. Lipopolysaccharide and over half of the cell envelope protein were associated with the membrane that banded in sucrose at ?° = 1.219 g/cm3. These fractions were consequently designated cytoplasmic and outer or L-membrane, respectively. Sodium dodecyl sulfate-polyacrylamide electrophoresis of isolated membranes demonstrated the relative simplicity of the protein spectrum of the outer membrane. The majority of the protein in this membrane could be accounted for by proteins of molecular weights 34,500, 22,000, and 11,500. The protein of molecular weight 34,500 accounted for 66% of the total protein of the L-membrane. Isoelectric precipitation at pH 4.6 with 10% acetic acid selectively removed this protein from a 150 mM NaCl in 10 mM tris(hydroxymethyl)aminomethane-hydrochloride, pH 7.4, extract of purified outer membrane. At pH 4.0, the other proteins of the L-membrane were precipitated. It was concluded that the membrane components of the cell envelope of N. gonorrhoeae were similar to those of other gram-negative bacteria. The cell envelope fractions described here, in particular the outer membrane, are sufficiently well defined to provide a valuable tool for future biochemical and immunological studies on N. gonorrhoeae.

Johnston, K. H.; Gotschlich, E. C.

1974-01-01

162

Preparative electrophoresis for space  

NASA Technical Reports Server (NTRS)

A premise of continuous flow electrophoresis is that removal of buoyance-induced thermal convection caused by axial and lateral temperature gradients results in ideal performance of these instruments in space. Although these gravity dependent phenomena disturb the rectilinear flow in the separation chamber when high voltage gradients or thick chamber are used, distortion of the injected sample stream due to electrodynamic effects cause major broadening of the separated bands. The electrophoresis separation process is simple, however flow local to the sample filament produced by the applied electric field were not considered. These electrohydrodynamic flows distort the sample stream and limit the separation. Also, electroosmosis and viscous flow combine to further distort the process. A moving wall concept is being proposed for space which will eliminate and control the disturbances. The moving wall entrains the fluid to move as a rigid body and produces a constant residence time for all samples distributed across the chamber thickness. The moving wall electrophoresis chamber can only be operated in space because there is no viscous flow in the chamber to stabilize against thermal convection.

Rhodes, Percy H.; Snyder, Robert S.

1988-01-01

163

Preparative electrophoresis for space  

NASA Technical Reports Server (NTRS)

A premise of continuous flow electrophoresis is that removal of buoyancy-induced thermal convection caused by axial and lateral temperature gradients results in ideal performance of these instruments in space. Although these gravity dependent phenomena disturb the rectilinear flow in the separation chamber when high voltage gradients or thick chambers are used, distortion of the injected sample stream due to electrohydrodynamic effects cause major broadening of the separated bands. The electrophoresis separation process is simple, however flow local to the sample filament produced by the applied electric field have not been considered. These electrohydrodynamic flows distort the sample stream and limit the separation. Also, electroosmosis and viscous flow combine to further distort the process. A moving wall concept is being proposed for space which will eliminate and control the disturbances. The moving wall entrains the fluid to move as a rigid body and produces a constant residence time for all samples distributed across the chamber thickness. The moving wall electrophoresis chamber can only be operated in space because there is no viscous flow in the chamber to stabilize against thermal convection.

Rhodes, Percy H.; Snyder, Robert S.

1987-01-01

164

Electrophoresis experiments in microgravity  

NASA Technical Reports Server (NTRS)

The use of the microgravity environment to separate and purify biological cells and proteins has been a major activity since the beginning of the NASA Microgravity Science and Applications program. Purified populations of cells are needed for research, transplantation and analysis of specific cell constituents. Protein purification is a necessary step in research areas such as genetic engineering where the new protein has to be separated from the variety of other proteins synthesized from the microorganism. Sufficient data are available from the results of past electrophoresis experiments in space to show that these experiments were designed with incomplete knowledge of the fluid dynamics of the process including electrohydrodynamics. However, electrophoresis is still an important separation tool in the laboratory and thermal convection does limit its performance. Thus, there is a justification for electrophoresis but the emphasis of future space experiments must be directed toward basic research with model experiments to understand the microgravity environment and fluid analysis to test the basic principles of the process.

Snyder, Robert S.; Rhodes, Percy H.

1991-01-01

165

Membranes for Reverse Osmosis by Direct Casting on Porous Supports.  

National Technical Information Service (NTIS)

Cellulose acetate membranes cast under a variety of conditions on various support materials were tested with a standard 1% sodium chloride at different pressures. The objective was to examine the possibility of casting thin cellulose acetate membranes on ...

R. L. Nickelson E. A. Birkhimer D. E. Coverdell J. Y. Lai D. G. Wang

1970-01-01

166

Study of Mass Transfer in Membrane Processes.  

National Technical Information Service (NTIS)

Electrical potential differences across membranes were measured with both an anion-exchange membrane used in electrodialysis and a modified cellulose acetate membrane used in reverse osmosis. These measurements were performed in special apparatus which on...

K. S. Spiegler

1970-01-01

167

High-throughput genotyping of factor V Leiden mutation by ultrathin-layer agarose gel electrophoresis  

Microsoft Academic Search

Ultrathin-layer agarose gel electrophoresis is a novel combination of the established methodologies of slab gel electrophoresis and capillary gel electrophoresis. This new format provides a multilane separation platform with rapid analysis time and excellent sensitivity by using laser-induced fluorescence scanning detection system. Sample injection onto the ultrathin-layer separation platform is easily accomplished by membrane mediated loading technology. In this paper,

Timea Lengyel; Maria Sasvari-Szekely; Andras Guttman

1999-01-01

168

Determination of terbinafine in pharmaceuticals and dialyzates by capillary electrophoresis.  

PubMed

A capillary electrophoresis method has been developed for the separation and determination of terbinafine (TER) in various pharmaceutically relevant matrices. Capillary zone electrophoresis (CZE) separation and UV absorbance photometric detection were carried out in a 160mm capillary tube with a 300mum i.d., hydrodynamically (membrane) closed. The influences of pH, carrier cation and counterion on migration parameters of TER were studied and the following conditions were selected: a 20mmoll(-1) glycine running buffer adjusted to pH 2.7 with acetic acid, 0.2% (w/v) methylhydroxyethylcellulose (m-HEC) as an electro-osmotic flow (EOF) suppressor, a 250muA driving current, and 20 degrees C. The optimized separation conditions were convenient for the determination of TER in commercial tablets and spray and in dialyzates. Here, the dialysis was used to investigate in vitro permeation of TER through the skin from the gel. The samples of dialyzates were examined with and without simple extraction procedure and the results were compared. A permeation profile of the drug present in the gel of given composition was obtained analyzing pretreated samples. The proposed electrophoretic method was successfully validated. It was suitable for the simple, sensitive, rapid and highly reproducible assay of TER. CZE analysis was completed within 5.5min. The detection limit of TER was 1.73mumoll(-1) at a 224nm detection wavelength. The intra- and inter-laboratory precisions over the concentration range 6.0-60.0mumoll(-1) were between 0.32-0.69% and 1.04-1.44% including R.S.D. of migration times and peak areas, respectively. The mean absolute recoveries of drugs from samples were found to be 98.34 (tablets) and 99.47% (spray). It is suggested that there are potentialities to determine TER present in unpretreated complex samples, as CZE in a hydrodynamically closed separation system may be easily on-line combinable with purification and preconcentration CE modes (e.g., isotachophoresis, ITP). PMID:18969906

Mikus, Peter; Valásková, Iva; Havránek, Emil

2005-02-28

169

Multiplexed capillary electrophoresis system  

DOEpatents

The invention provides a side-entry optical excitation geometry for use in a multiplexed capillary electrophoresis system. A charge-injection device is optically coupled to capillaries in the array such that the interior of a capillary is imaged onto only one pixel. In Sanger-type 4-label DNA sequencing reactions, nucleotide identification ("base calling") is improved by using two long-pass filters to split fluorescence emission into two emission channels. A binary poly(ethyleneoxide) matrix is used in the electrophoretic separations.

Yeung, Edward S. (Ames, IA); Chang, Huan-Tsang (Silver Spring, MD); Fung, Eliza N. (Ames, IA); Li, Qingbo (Ames, IA); Lu, Xiandan (Ames, IA)

1996-12-10

170

Multiplexed capillary electrophoresis system  

DOEpatents

The invention provides a side-entry optical excitation geometry for use in a multiplexed capillary electrophoresis system. A charge-injection device is optically coupled to capillaries in the array such that the interior of a capillary is imaged onto only one pixel. In Sanger-type 4-label DNA sequencing reactions, nucleotide identification ("base calling") is improved by using two long-pass filters to split fluorescence emission into two emission channels. A binary poly(ethyleneoxide) matrix is used in the electrophoretic separations.

Yeung, Edward S. (Ames, IA); Li, Qingbo (Ames, IA); Lu, Xiandan (Ames, IA)

1998-04-21

171

Multiplexed capillary electrophoresis system  

DOEpatents

The invention provides a side-entry optical excitation geometry for use in a multiplexed capillary electrophoresis system. A charge-injection device is optically coupled to capillaries in the array such that the interior of a capillary is imaged onto only one pixel. In Sanger-type 4-label DNA sequencing reactions, nucleotide identification (``base calling``) is improved by using two long-pass filters to split fluorescence emission into two emission channels. A binary poly(ethyleneoxide) matrix is used in the electrophoretic separations. 19 figs.

Yeung, E.S.; Chang, H.T.; Fung, E.N.; Li, Q.; Lu, X.

1996-12-10

172

Multiplexed capillary electrophoresis system  

DOEpatents

The invention provides a side-entry optical excitation geometry for use in a multiplexed capillary electrophoresis system. A charge-injection device is optically coupled to capillaries in the array such that the interior of a capillary is imaged onto only one pixel. In Sanger-type 4-label DNA sequencing reactions, nucleotide identification (``base calling``) is improved by using two long-pass filters to split fluorescence emission into two emission channels. A binary poly(ethyleneoxide) matrix is used in the electrophoretic separations. 19 figs.

Yeung, E.S.; Li, Q.; Lu, X.

1998-04-21

173

Detection of Polymorphisms of Human DNA by Gel Electrophoresis as Single-Strand Conformation Polymorphisms  

Microsoft Academic Search

We developed mobility shift analysis of single-stranded DNAs on neutral polyacrylamide gel electrophoresis to detect DNA polymorphisms. This method follows digestion of genomic DNA with restriction endonucleases, denaturation in alkaline solution, and electrophoresis on a neutral polyacrylamide gel. After transfer to a nylon membrane, the mobility shift due to a nucleotide substitution of a single-stranded DNA fragment could be detected

Masato Orita; Hiroyuki Iwahana; Hiroshi Kanazawa; Kenshi Hayashi; Takao Sekiya

1989-01-01

174

Primitive Model Electrophoresis.  

PubMed

The electrophoresis of a spherical macroion is calculated with the new primitive model electrophoresis (PME) theory, which incorporates the ionic size. The results are compared with the classical theory of Wiersema, O'Brien, and White. The PME mobility, as a function of the macroion's surface charge (sigma) or zeta potential (zeta), is found to depend on the ionic valence, radius and concentration, and macroion hydrodynamical radius (A); i.e., it is not universal with kappaA, as predicted by the classical theory. The mobility is very nonlinear as a function of zeta. This behavior is related to the nonlinear dependence of zeta, as a function of sigma, when ionic size is included in the theory. In the classical theory zeta is a monotonic function of sigma. Important quantitative and/or qualitative differences between PME and the classical theory are found. However, in the limit of zero ionic diameter, and/or low salt concentration, and low macroion charge, the new theory reduces to the classical theory. The agreement of the PME with experimental data is very good. In particular, the prediction of reversed mobility is corroborated by recent experimental data. Copyright 2001 Academic Press. PMID:11426992

Lozada-Cassou, Marcelo; González-Tovar, Enrique

2001-07-15

175

Preparation of vinyl acetate  

DOEpatents

This invention pertains to the preparation of vinyl acetate by contacting a mixture of hydrogen and ketene with a heterogeneous catalyst containing a transition metal to produce acetaldehyde, which is then reacted with ketene in the presence of an acid catalyst to produce vinyl acetate.

Tustin, Gerald Charles (Kingsport, TN); Zoeller, Joseph Robert (Kingsport, TN); Depew, Leslie Sharon (Kingsport, TN)

1998-01-01

176

Preparation of vinyl acetate  

DOEpatents

This invention pertains to the preparation of vinyl acetate by contacting a mixture of hydrogen and ketene with a heterogeneous catalyst containing a transition metal to produce acetaldehyde, which is then reacted with ketene in the presence of an acid catalyst to produce vinyl acetate.

Tustin, G.C.; Zoeller, J.R.; Depew, L.S.

1998-03-24

177

Determination of yessotoxins and pectenotoxins in shellfish by capillary electrophoresis-electrospray ionization-mass spectrometry  

Microsoft Academic Search

Conditions for the determination of lipophilic marine toxins, such as yessotoxins and pectenotoxins (PTX)-6, were investigated with capillary electrophoresis coupled to mass spectrometry (MS) with an electrospray ionization source. After optimization, a simple and MS compatible alkaline volatile buffer solution of ammonium acetate was selected as background electrolyte, with isopropanol\\/water (80\\/20, v\\/v) sheath liquid modified with ammonium acetate used at

P. de la Iglesia; A. Gago-Martínez

2009-01-01

178

Cellulose acetate graft copolymers with nano-structured architectures: Synthesis and characterization  

Microsoft Academic Search

Cellulose acetate is a very good film-forming polymer with major applications in cigarette filters, photographic films, cosmetics and pharmaceutics formulations and membrane separation processes. Nevertheless, its rigidity and relative hydrophobic character can be limiting drawbacks for some applications. In this work, new cellulose acetate materials with highly flexible and hydrophilic grafts were obtained with different hydrophilic\\/hydrophobic balances. Cellulose acetate was

M. Billy; A. Ranzani Da Costa; P. Lochon; R. Clément; M. Dresch; S. Etienne; J. M. Hiver; L. David; A. Jonquières

2010-01-01

179

Electrophoresis experiment for space  

NASA Technical Reports Server (NTRS)

The Apollo 16 electrophoresis experiment was analyzed, demonstrating that the separation of the two different-size monodisperse latexes did indeed take place, but that the separation was obscured by the pronounced electroosmotic flow of the liquid medium. The results of this experiment, however, were dramatic since it is impossible to carry out a similar separation on earth. It can be stated unequivocally from this experiment that any electrophoretic separation will be enhanced under microgravity conditions. The only question is the degree of this enhancement, which can be expected to vary from one experimental technique to another. The low-electroosmotic-mobility coating (Z6040-MC) developed under this program was found to be suitable for a free-fluid electrophoretic separation such as the experiment designed for the ASTP flight. The problem with this coating, however, is that its permanency is limited because of the slow desorption of the methylcellulose from the coated surface.

Vanderhoff, J. W.; Micale, F. J.

1976-01-01

180

Static continuous electrophoresis device  

NASA Technical Reports Server (NTRS)

An apparatus is disclosed for carrying out a moving wall type electrophoresis process for separation of cellular particles. The apparatus includes a water-tight housing containing an electrolytic buffer solution. A separation chamber in the housing is defined by spaced opposed moving walls and spaced opposed side walls. Substrate assemblies, which support the moving wall include vacuum ports for positively sealing the moving walls against the substrate walls. Several suction conduits communicate with the suction ports and are arranged in the form of valleys in a grid plate. The raised land portion of the grid plat supports the substrate walls against deformation inwardly under suction. A cooling chamber is carried on the back side of plate. The apparatus also has tensioner means including roller and adjustment screws for maintaining the belts in position and a drive arrangement including an electric motor with a gear affixed to its output shaft. Electrode assemblies are disposed to provide the required electric field.

Rhodes, P. H. (inventor)

1982-01-01

181

Nanofabrication in cellulose acetate.  

PubMed

We have demonstrated nanofabrication with commercialized cellulose acetate. Cellulose acetate is used for bulk nanofabrication and surface nanofabrication. In bulk nanofabrication, cellulose acetate reacts with an e-beam and permanent patterns are formed in it instead of being transferred to other substrates. We have studied the nano relief modulation performance of cellulose acetate before and after development. The depth of the nanopatterns is magnified after development, and is varied by exposing dosage and line width of the pattern. The thinnest 65 nm wide line is achieved in the bulk fabrication. We also demonstrate a binary phase Fresnel lens array which is directly patterned in a cellulose acetate sheet. Because of its unique mechanical and optical properties, cellulose is a good candidate for a template material for soft imprinting lithography. In the surface nanofabrication, cellulose acetate thin film spin-coated on silicon wafers is employed as a new resist for e-beam lithography. We achieved 50 nm lines with 100 nm pitches, dots 50 nm in diameter, and single lines with the smallest width of 20 nm. As a new resist of e-beam lithography, cellulose acetate has high resolution comparable with conventional resists, while having several advantages such as low cost, long stock time and less harmfulness to human health. PMID:19224020

Zeng, Hongjun; Lajos, Robert; Metlushko, Vitali; Elzy, Ed; An, Se Young; Sautner, Joshua

2009-03-01

182

Kidney cell electrophoresis, continuing task  

NASA Technical Reports Server (NTRS)

Materials and procedures for microgravity electrophoresis of living human embryonic kidney cells were evaluated to provide ground support in the form of analytical cell electrophoresis and flow cytometry. Preflight culture media, electrophoresis buffer, fraction collection media, temperature profiles, and urokinase assay procedures were tested prior to flight. Electrophoretic mobility distributions of aliquots of the cell population to be fractionated in flight were obtained. Cells were prepared in suspension prior to flight in electrophoresis buffer and 10% calf serum. Electrophoretic separation proceeded in electrophoresis buffer without serum in the Continuous Flow Electrophoretic Separator, and fractions were collected into sample bags containing culture medium and concentrated serum. Fractions that yielded enough progeny cells were analyzed for morphology and electrophoretic mobility distributions. It is noted that the lowest mobility fraction studied produced higher mobility progeny while the other fractions produced progeny cells with mobilities related to the fractions from which they were collected.

Todd, P. W.

1985-01-01

183

Electrophoresis demonstration on Apollo 16  

NASA Technical Reports Server (NTRS)

Free fluid electrophoresis, a process used to separate particulate species according to surface charge, size, or shape was suggested as a promising technique to utilize the near zero gravity condition of space. Fluid electrophoresis on earth is disturbed by gravity-induced thermal convection and sedimentation. An apparatus was developed to demonstrate the principle and possible problems of electrophoresis on Apollo 14 and the separation boundary between red and blue dye was photographed in space. The basic operating elements of the Apollo 14 unit were used for a second flight demonstration on Apollo 16. Polystyrene latex particles of two different sizes were used to simulate the electrophoresis of large biological particles. The particle bands in space were extremely stable compared to ground operation because convection in the fluid was negligible. Electrophoresis of the polystyrene latex particle groups according to size was accomplished although electro-osmosis in the flight apparatus prevented the clear separation of two particle bands.

Snyder, R. S.

1972-01-01

184

Salt-induced changes in the plasma membrane proteome of the halotolerant alga Dunaliella salina as revealed by blue native gel electrophoresis and nano-LC-MS/MS analysis.  

PubMed

The halotolerant alga Dunaliella salina is a recognized model photosynthetic organism for studying plant adaptation to high salinity. The adaptation mechanisms involve major changes in the proteome composition associated with energy metabolism and carbon and iron acquisition. To clarify the molecular basis for the remarkable resistance to high salt, we performed a comprehensive proteomics analysis of the plasma membrane. Plasma membrane proteins were recognized by tagging intact cells with a membrane-impermeable biotin derivative. Proteins were resolved by two-dimensional blue native/SDS-PAGE and identified by nano-LC-MS/MS. Of 55 identified proteins, about 60% were integral membrane or membrane-associated proteins. We identified novel surface coat proteins, lipid-metabolizing enzymes, a new family of membrane proteins of unknown function, ion transporters, small GTP-binding proteins, and heat shock proteins. The abundance of 20 protein spots increased and that of two protein spots decreased under high salt. The major salt-regulated proteins were implicated in protein and membrane structure stabilization and within signal transduction pathways. The migration profiles of native protein complexes on blue native gels revealed oligomerization or co-migration of major surface-exposed proteins, which may indicate mechanisms of stabilization at high salinity. PMID:17569891

Katz, Adriana; Waridel, Patrice; Shevchenko, Andrej; Pick, Uri

2007-09-01

185

((35)S)sulfate incorporation into glomerular basement membrane glycosaminoglycans is decreased in experimental diabetes  

SciTech Connect

Isolated rat renal glomeruli incorporate radioactive sulfate into glycosaminoglycans, which are integral components of the glomerular basement membrane. Cellulose acetate electrophoresis and specific enzymatic sensitivities of glycosaminoglycans prepared after pronase digestion of purified glomerular basement membrane indicate the presence of heparan sulfate. We examined the effect of experimental diabetes on the incorporation of ((35)S)-sulfate into glycosaminoglycans deposited into newly synthesized glomerular basement membrane in vitro. Basement membranes were purified from glomeruli isolated from normal and streptozotocin-diabetic rats after incubation for 2 hr with radiolabeled sulfate and then were subjected to pronase digestion for isolation of the glycosaminoglycans. ((35)S) incorporation into basement membrane glycosaminoglycans was significantly decreased in glomeruli from diabetic animals. The addition of insulin (100 micron U/ml) in vitro did not affect ((35)S) incorporation into glycosaminoglycans of the glomerular basement membranes in normal or diabetic glomeruli. High glucose concentration (5 vs. 20 mM) was without effect in short-term incubations of glomeruli from normal animals. The results indicate that experimental diabetes influences ((35)S) sulfate incorporation into glomerular basement membrane glycosaminoglycans and suggest that decreased heparan sulfate production and/or sulfation may contribute to the increased permeability of the glomerular basement membrane in diabetes.

Cohen, M.P.; Surma, M.L.

1981-11-01

186

Reptation theories of electrophoresis.  

PubMed

In this review, we present the main aspects of the reptation theory, which has provided an essential insight into the processes at work during DNA electrophoretic separation in gels. We avoid mathematical developments, and rely as much as possible on an intuitive description. We first present the original biased reptation model, which assumes that the DNA threads its way as a "worm" of fixed length among the fibers of the gel. We then introduce a more recent version, the model of Biased Reptation with Fluctuations (BRF), which allows for longitudinal flexibility along the DNA. We then propose a quantitative comparison with experiments performed in constant field, and discuss the application of reptation theories to pulsed field techniques either with crossed fields or with field inversion. We also discuss at some length the different experiments that led to a criticism of reptation ideas, such as orientation measurements and videomicroscopy. Finally, we use these experiments together with various computer simulations developed recently for gel electrophoresis, to propose a more realistic qualitative description of DNA motion in gels, and we discuss what elements in this motion are relevant to reptation and what processes are not included in present analytical models. PMID:8887359

Viovy, J L

1996-08-01

187

``Force-free'' electrophoresis?  

NASA Astrophysics Data System (ADS)

When a colloidal particle is exposed to an externally applied electric field, it acquires an electrophoretic velocity, resulting from fluid slip occurring across the Debye screening layer. When the field is uniformly applied, it is usually assumed that the net neutrality of the combined particle-layer system implies that the net electric force acting on it must vanish. This assumption of ``force-free'' phoretic motion has been employed extensively to describe electrophoresis in both unbounded and bounded fluid domains [J. L. Anderson, Annu. Rev. Fluid Mech. 21, 61 (1989)]. A careful inspection reveals here that this intuitive premise may fail when the fluid domain is bounded, in which case a nonzero electric force (resembling dielectrophoretic forces in nonuniformly applied fields) may actually exist. Such forces (represented via surface integrals of Maxwell stresses) result in particle motion above and beyond the one driven by the phoretic slip mechanism. A positive demonstration for the existence of a such a force is provided for a standard sphere-wall configuration, where the applied field acts parallel to the wall. In that scenario, particle motion consists of a (familiar) slip-driven contribution parallel to the wall, together with a superimposed force-driven drift away from the wall. An analogy with pressure forces occurring at incompressible and inviscid potential flows is presented.

Yariv, Ehud

2006-03-01

188

Mechanisms of acetate formation and acetate activation in halophilic archaea  

Microsoft Academic Search

The halophilic archaea Halococcus (Hc.) saccharolyticus, Haloferax (Hf.) volcanii, and Halorubrum (Hr.) saccharovorum were found to generate acetate during growth on glucose and to utilize acetate as a growth substrate. The mechanisms of acetate formation from acetyl-CoA and of acetate activation to acetyl-CoA were studied. Hc. saccharolyticus, exponentially growing on complex medium with glucose, formed acetate and contained ADP-forming acetyl-CoA

Christopher Bräsen; Peter Schönheit

2001-01-01

189

Electrophoresis for Under Five Dollars.  

ERIC Educational Resources Information Center

Equipped with a little more than batteries, food-dye, and sieving media, teachers can demonstrate an essential process used in biochemical research. An activity is provided to aid in helping students to understand electrophoresis. (ZWH)

Lumetta, Vincent J.; Doktycz, Mitchel J.

1994-01-01

190

Copolymers For Capillary Gel Electrophoresis  

DOEpatents

This invention relates to an electrophoresis separation medium having a gel matrix of at least one random, linear copolymer comprising a primary comonomer and at least one secondary comonomer, wherein the comonomers are randomly distributed along the copolymer chain. The primary comonomer is an acrylamide or an acrylamide derivative that provides the primary physical, chemical, and sieving properties of the gel matrix. The at least one secondary comonomer imparts an inherent physical, chemical, or sieving property to the copolymer chain. The primary and secondary comonomers are present in a ratio sufficient to induce desired properties that optimize electrophoresis performance. The invention also relates to a method of separating a mixture of biological molecules using this gel matrix, a method of preparing the novel electrophoresis separation medium, and a capillary tube filled with the electrophoresis separation medium.

Liu, Changsheng (State College, PA); Li, Qingbo (State College, PA)

2005-08-09

191

Electromembrane extraction of amino acids from body fluids followed by capillary electrophoresis with capacitively coupled contactless conductivity detection.  

PubMed

Electromembrane extraction (EME) proved to be a simple and rapid pretreatment method for analysis of amino acids and related compounds in body fluid samples. Body fluids were acidified to the final concentration of 2.5 M acetic acid and served as donor solutions. Amino acids, present as cations in the donor solutions, migrated through a supported liquid membrane (SLM) composed of 1-ethyl-2-nitrobenzene/bis-(2-ethylhexyl)phosphonic acid (85:15 (v/v)) into the lumen of a porous polypropylene hollow fiber (HF) on application of electric field. The HF was filled with 2.5 M acetic acid serving as the acceptor solution. Matrix components in body fluids were efficiently retained on the SLM and did not interfere with subsequent analysis. Capillary electrophoresis with capacitively coupled contactless conductivity detection was used for determination of 17 underivatized amino acids in background electrolyte solution consisting of 2.5 M acetic acid. Parameters of EME, such as composition of SLM, pH and composition of donor and acceptor solution, agitation speed, extraction voltage, and extraction time were studied in detail. At optimized conditions, repeatability of migration times and peak areas of 17 amino acids was better than 0.3% and 13%, respectively, calibration curves were linear in a range of two orders of magnitude (r(2)=0.9968-0.9993) and limits of detection ranged from 0.15 to 10 ?M. Endogenous concentrations of 12 amino acids were determined in EME treated human serum, plasma, and whole blood. The method was also suitable for simple and rapid pretreatment and determination of elevated concentrations of selected amino acids, which are markers of severe inborn metabolic disorders. PMID:21824620

Strieglerová, Lenka; Kubá?, Pavel; Bo?ek, Petr

2011-09-16

192

Determination of glycoalkaloids and relative aglycones by nonaqueous capillary electrophoresis coupled with electrospray ionization-ion trap mass spectrometry.  

PubMed

Glycoalkaloids are naturally occurring nitrogen-containing compounds present in many species of the family Solanaceae, including cultivated and wild potatoes (Solanum spp.), tomatoes (Lycopersicon spp.), etc. These compounds have pharmacological and toxicological effects on humans due to their significant anticholinesterase activity and disruption of cell membranes. Herein is reported the development of a capillary electrophoresis (CE) method using nonaqueous (NA) separation solutions in combination with ion trap mass spectrometry (MS and MS/MS) detection for the identification and quantification of glycoalkaloids and their relative aglycones. A mixture 90:10 v/v of MeCN-MeOH containing 50 mM ammonium acetate and 1.2 M acetic acid (applied voltage of 25.5 kV) was selected as a good compromise for the separation and detection of these compounds. The electrospray MS measurements were carried out in the positive ionization mode using a coaxial sheath liquid, methanol-water (1:1) with 1% of acetic acid at a flow rate of 2.5 microL/min. Under optimized experimental conditions, the predominant ion was the protonated molecular ion ([M+H](+)) of solanidine (m/z = 398), tomatidine (m/z = 416), chaconine (m/z = 852), solanine (m/z = 868), and tomatine (m/z = 1034). MS/MS experiments were carried out systematically by changing the relative collisional energy and monitoring the intensities of the fragment ions that were not high enough to allow better quantification than with the mother ions. The method was used for analyzing glycoalkaloids in potato extracts. PMID:12207298

Bianco, Giuliana; Schmitt-Kopplin, Philippe; De Benedetto, Giuseppe; Kettrup, Antonius; Cataldi, Tommaso R I

2002-09-01

193

Membrane Processes (Osmosis and Reverse Osmosis).  

National Technical Information Service (NTIS)

Previous work on the general problem of making more productive reverse osmosis membranes resulted in new classes of porous cellulose acetate reverse osmosis membranes for low pressure work of highly increased (100%) productivities, as well as in a new con...

B. Kunst G. Arneri P. Goran A. M. Basnec

1973-01-01

194

Membranes for Desalination by Reverse Osmosis.  

National Technical Information Service (NTIS)

'Salt leakage' through cellulose acetate membranes may take place through regions of very low polymer density or 'defects' in the membrane. Research was carried out to increase the salt rejection efficiency by selectively eliminating defects which are ion...

L. L. Markley R. A. Cross H. J. Bixler

1967-01-01

195

Comparison of the phosphorylation events in membranes prepared from proliferating versus quiescent endothelial cells  

SciTech Connect

Little is known of the intracellular events which regulate the proliferation of endothelial cells (EC). Triton-solubilized membranes from proliferating (sparse) and quiescent (confluent) EC were incubated at pH 6.5 in the presence of divalent cations and (/sup 32/P)ATP. Membrane proteins were analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis and autoradiography. The overall kinase activity per mg protein was slightly greater in membranes prepared from proliferating versus quiescent cells. They found four proteins labeled in sparse cells to a dramatically greater extent having the following approximate molecular masses: 180, 100, 97 and 55 kilodalton (kd). The first two phosphoproteins were phosphorylated on serine residues exclusively; the 97 kd phosphoprotein contained 39% phosphoserine (p-ser) and 61% phosphothreonine (p-thr); and the 55 kd phosphoprotein contained 62% p-ser, 16% p-thr, and 22% phosphotyrosine (p-tyr). The kinases acting on all four phosphoproteins were independent of Ca/sup 2 +/, cAMP, cGMP, or phorbol 12-myristate 13-acetate. The observed differences in phosphorylation events between sparse and confluent membranes occurred in membranes from two EC lines - pig aortic and bovine aortic - but were not apparent in membranes prepared from human foreskin fibroblasts or 3T3 cells. Sparse endothelial cells made quiescent by serum deprivation were found to resemble confluent cells in the kinase activity; therefore, the enhanced kinase activity in sparse membranes may be growth dependent.

Kazlauskas, A.; DiColeto, P.E.

1986-05-01

196

On-Column Electrochemical Detection for Microchip Capillary Electrophoresis  

PubMed Central

The development of a cellulose acetate decoupler for on-column electrochemical detection in microchip capillary electrophoresis is presented. The capillary based laser-etched decoupler is translated to the planar format to isolate the detector circuit from the separation circuit. The decoupler is constructed by aligning a series of 20 30-?m holes through the coverplate of the microchip with the separation channel and casting a thin film of cellulose acetate within the holes. The decoupler shows excellent isolation of the detection circuit for separation currents up to 60 ?A, with noise levels at or below 1 pA at a carbon fiber electrode. Detection limits of 25 nM were achieved for dopamine. This decoupler design combines excellent mechanical stability, effective shunting of high separation currents, and ease of manufacture.

Osbourn, Damon M.; Lunte, Craig E.

2008-01-01

197

On-column electrochemical detection for microchip capillary electrophoresis.  

PubMed

The development of a cellulose acetate decoupler for on-column electrochemical detection in microchip capillary electrophoresis is presented. The capillary based laser-etched decoupler is translated to the planar format to isolate the detector circuit from the separation circuit. The decoupler is constructed by aligning a series of 20 30-microm holes through the coverplate of the microchip with the separation channel and casting a thin film of cellulose acetate within the holes. The decoupler shows excellent isolation of the detection circuit for separation currents up to 60 microA, with noise levels at or below 1 pA at a carbon fiber electrode. Detection limits of 25 nM were achieved for dopamine. This decoupler design combines excellent mechanical stability, effective shunting of high separation currents, and ease of manufacture. PMID:12948140

Osbourn, Damon M; Lunte, Craig E

2003-06-01

198

Radiation sterilization of hydrocortisone acetate.  

National Technical Information Service (NTIS)

The feasibility of using high energy ionizing radiation for the sterilization of hydrocortisone acetate was investigated. Hydrocortisone acetate in the form of powder was exposed to different dose levels of gamma radiation using a Cobalt-60 source. The ir...

A. Charef A. Boussaha

1989-01-01

199

Contactless conductivity detector for microchip capillary electrophoresis  

NASA Technical Reports Server (NTRS)

A microfabricated electrophoresis chip with an integrated contactless conductivity detection system is described. The new contactless conductivity microchip detector is based on placing two planar sensing aluminum film electrodes on the outer side of a poly(methyl methacrylate) (PMMA) microchip (without contacting the solution) and measuring the impedance of the solution in the separation channel. The contactless route obviates problems (e.g., fouling, unwanted reactions) associated with the electrode-solution contact, offers isolation of the detection system from high separation fields, does not compromise the separation efficiency, and greatly simplifies the detector fabrication. Relevant experimental variables, such as the frequency and amplitude of the applied ac voltage or the separation voltage, were examined and optimized. The detector performance was illustrated by the separation of potassium, sodium, barium, and lithium cations and the chloride, sulfate, fluoride, acetate, and phosphate anions. The response was linear (over the 20 microM-7 mM range) and reproducible (RSD = 3.4-4.9%; n = 10), with detection limits of 2.8 and 6.4 microM (for potassium and chloride, respectively). The advantages associated with the contactless conductivity detection, along with the low cost of the integrated PMMA chip/detection system, should enhance the power and scope of microfluidic analytical devices.

Pumera, Martin; Wang, Joseph; Opekar, Frantisek; Jelinek, Ivan; Feldman, Jason; Lowe, Holger; Hardt, Steffen; Svehla, D. (Principal Investigator)

2002-01-01

200

Contactless conductivity detector for microchip capillary electrophoresis.  

PubMed

A microfabricated electrophoresis chip with an integrated contactless conductivity detection system is described. The new contactless conductivity microchip detector is based on placing two planar sensing aluminum film electrodes on the outer side of a poly(methyl methacrylate) (PMMA) microchip (without contacting the solution) and measuring the impedance of the solution in the separation channel. The contactless route obviates problems (e.g., fouling, unwanted reactions) associated with the electrode-solution contact, offers isolation of the detection system from high separation fields, does not compromise the separation efficiency, and greatly simplifies the detector fabrication. Relevant experimental variables, such as the frequency and amplitude of the applied ac voltage or the separation voltage, were examined and optimized. The detector performance was illustrated by the separation of potassium, sodium, barium, and lithium cations and the chloride, sulfate, fluoride, acetate, and phosphate anions. The response was linear (over the 20 microM-7 mM range) and reproducible (RSD = 3.4-4.9%; n = 10), with detection limits of 2.8 and 6.4 microM (for potassium and chloride, respectively). The advantages associated with the contactless conductivity detection, along with the low cost of the integrated PMMA chip/detection system, should enhance the power and scope of microfluidic analytical devices. PMID:12033293

Pumera, Martin; Wang, Joseph; Opekar, Frantisek; Jelínek, Ivan; Feldman, Jason; Löwe, Holger; Hardt, Steffen

2002-05-01

201

Introduction to Agarose Gel Electrophoresis  

NSDL National Science Digital Library

In this module, developed as part of Cornell's Learning Initiative in Medicine and Bioengineering (CLIMB), students are introduced to the concepts of gel electrophoresis without requiring all the equipment needed to run a full gel electrophoresis experiment. The goal is to have students understand how gels are made for DNA separation and how altering the composition can affect the experimental parameters. This module contains a teacher's guide, classroom activity, and suggestions for extended activities. This lab is a precursor to Cornellâs Institute for Biology Teachers labâs entitled DNA Profiling â Paternity Testing, which is linked within the teacher's guide. CLIMB is part of the NSF GK-12 program.

Bioengineering, Climb: C.

202

Search for New Desalination Membranes.  

National Technical Information Service (NTIS)

Chitin has been deacetylated to produce chitosan. Chitosan salt films have been cast from dilute acetic acid solvent and free amine films have been generated by an alkali coagulation technique. The water content of these films and coagulated membranes is ...

S. Mukherjee P. Luner

1972-01-01

203

Polyaniline Membranes for Separation Applications.  

National Technical Information Service (NTIS)

High quality membranes of poly aniline/ethylaniline copolymers along with polyaniline/polyimide blends have been synthesized. Water permeates preferentially over organic (such as acetic acid) through doped poly aniline due to a combination of favorable di...

R. B. Kaner

1997-01-01

204

Acetate Production by Methanogenic Bacteria  

PubMed Central

Methanosarcina barkeri MS and 227 and Methanosarcina mazei S-6 produced acetate when grown on H2-CO2, methanol, or trimethylamine. Marked differences in acetate production by the two bacterial species were found, even though methane and cell yields were nearly the same. M. barkeri produced 30 to 75 ?mol of acetate per mmol of CH4 formed, but M. mazei produced only 8 to 9 ?mol of acetate per mmol of CH4.

Westermann, Peter; Ahring, Birgitte K.; Mah, Robert A.

1989-01-01

205

Electrophoretic characterization of a detergent-treated plasma membrane fraction from corn roots.  

PubMed

Experiments were conducted to determine conditions essential for electrophoretic characterization of a detergent-extracted plasma membrane fraction from corn (Zea mays L.) roots. Sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis (PAGE) initially gave poor resolution of polypeptides in the plasma membrane fraction and, upon detergent treatment for purification of the proton-pumping adenosine triphosphatase (ATPase), showed no enrichment for a 100 kilodalton catalytic subunit characteristic of the ATPase. In contrast to SDS-PAGE, phenol urea acetic acid (PAU)-PAGE clearly resolved two polypeptides in the 100 kilodalton region that were enriched during detergent treatment and indicated at least one polypeptide forms a phosphorylated intermediate characteristic of the ATPase. Problems with SDS-PAGE were found to be caused, in part, by a combination of endogenous proteases and heat-induced aggregation of high molecular weight proteins. The usually standard procedure of boiling the sample prior to SDS-PAGE caused the aggregation of the 100 kilodalton polypeptides. By controlling for proteases using chymostatin and/or phenylmethane sulfonyl floride, and not boiling the sample prior to electrophoresis, two polypeptides were clearly resolved by SDS-PAGE in the 100 kilodalton region of Triton X-114-extracted membranes from corn, oat, barley, and tomato. PMID:16665234

Gallagher, S R; Leonard, R T

1987-02-01

206

Acet-oxy-?-valerolactone  

PubMed Central

Levulinyl cellulose esters have been produced as an effective renewable binder for architectural coatings. The title compound, C7H10O4 (systematic name: 2-methyl-5-oxo­tetra­hydro­furan-2-yl acetate), assigned as the esterifying species, was isolated and crystallized to confirm the structure. In the crystal, the mol­ecules pack in layers parallel to (102) utilizing weak C—H?O inter­actions.

Tristram, Cameron; Gainsford, Graeme J.; Hinkley, Simon

2013-01-01

207

Plasma acetate turnover and oxidation.  

PubMed Central

Plasma acetate turnover and oxidation were determined in 11 healthy subjects by the constant infusion of a trace amount of [1-14C]acetate for 6 h. The subjects ages ranged from 22 to 57 yr. There was a positive correlation (P less than 0.001) between plasma acetate concentration and turnover rate, and a negative correlation (P less than 0.001) between turnover and age. The plasma acetate concentration in the subjects 22--28 yr old was 0.17 vs. 0.13 mM (P less than 0.02) in subjects 40--57 yr old. The plasma acetate turnover rate was also greater in the younger age group (8.23 +/- 0.66 vs. 4.98 +/- 0.64 mumol/min . kg, P less than 0.01). Approximately 90% of the plasma acetate turnover was immediately oxidized to CO2 in both age groups, however, 13.2 +/- 0.89% of the CO2 output in the younger group was derived from plasma acetate oxidation compared to 7.9 +/- 0.94% in the older group (P less than 0.01). The mean plasma acetate concentration, turnover, and oxidation in six cancer patients 47--63 yr old were similar to the values observed in the age-matched healthy subjects. Uptake or output of acetate by various tissues was measured by arterial-venous plasma acetate concentration differences. In seven of eight subjects undergoing elective surgery, the arterial-portal venous concentration difference was negative, which indicated that the gastrointestinal tract can contribute to plasma acetate production. Uptake of plasma acetate by both the leg and liver appeared to be dictated by the arterial acetate concentration. Net production of acetate by both the leg and liver was most often observed at arterial plasma acetate concentrations less than 0.08 mM.

Skutches, C L; Holroyde, C P; Myers, R N; Paul, P; Reichard, G A

1979-01-01

208

DNA electrophoresis in microfabricated devices  

NASA Astrophysics Data System (ADS)

Picking up at the conclusion of Viovy’s review of the physics of gel electrophoresis [J.-L. Viovy, Rev. Mod. Phys. 72, 813 (2000)10.1103/RevModPhys.72.813], this review synthesizes the experimental data, theoretical models, and simulation results for DNA electrophoresis in microfabricated and nanofabricated devices appearing since the seminal paper by Volkmuth and Austin [Nature (London) 358, 600 (1992)10.1038/358600a0]. Prototype versions of these devices separate DNA by molecular weight at a rate far superior to gel electrophoresis. After providing an overview of the requisite background material in polymer physics, electrophoresis, and microfluidic device fabrication, the focus is on the following three generic problems: (i) collision with an isolated post, (ii) transport in an array of posts, and (iii) entropic trapping and filtration in the slit-well motif. The transport phenomena are examined here in the context of the length and time scales characterizing the DNA, the device, and the applied electric field.

Dorfman, Kevin D.

2010-10-01

209

Capillary electrophoresis in food analysis  

Microsoft Academic Search

Unlike other chromatographic methods such as gas chromatography and high performance liquid chromatography which were routinely used in almost all food labs, capillary electrophoresis is relatively a novice in food science, the detection limits and low process sample volume is the Achilles’ heel of this technique. Nevertheless, with ease of its high resolving power, rapid method development, easy sample preparation

Yiyang Dong

1999-01-01

210

Cell morphology variations of Klebsiella pneumoniae induced by acetate stress using biomimetic vesicle assay.  

PubMed

Supplementation with acetate under low levels was used as a novel approach to control the morphological development of Klebsiella pneumoniae aimed to improve 1,3-propanediol (1,3-PD) production. A full range of morphological types formed from rod shape to oval shape even round shape in response to different concentrations of acetate. The cell growth and 1,3-PD productions in the shake flasks with 0.5 g/L acetate addition were improved by 9.4 and 28.37%, respectively, as compared to the control, while the cell became shorter and began to lose its original shape. The cell membrane penetration by acetate was investigated by the biomimetic vesicles, while higher concentration of acetate led to more moderate colorimetric transitions. Moreover, the percentage composition of unsaturated fatty acid (UFA) was increased as well as the increased concentrations of acetate, whereas higher UFA percentage, higher fluidity of bacterial cell membrane. PMID:23892619

Lu, Shengguo; Han, Yuwang; Duan, Xujia; Luo, Fang; Zhu, Lingyan; Li, Shuang; Huang, He

2013-10-01

211

Characterization of the formyl peptide chemotactic receptor appearing at the phagocytic cell surface after exposure to phorbol myristate acetate.  

PubMed

We examined the biochemistry and subcellular source of new formyl peptide chemotactic receptor appearing at the human neutrophil and differentiated HL-60 (d-HL-60) cell surface after stimulation with phorbol myristate acetate (PMA). Formyl peptide receptor was analyzed by affinity labeling with formyl-norleu-leu-phe-norleu-[125I]iodotyr-lys and ethylene glycol bis(succinimidyl succinate) followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and densitometric analysis of autoradiographs. PMA, a specific granule secretagogue, increases affinity labeling of formyl peptide receptors on the neutrophil surface by 100%, and on d-HL-60, which lack specific granule markers, by 20%. Papain treatment markedly reduces surface labeling of formyl peptide receptor in both neutrophils and d-HL-60, and results in the appearance of a lower m.w. membrane-bound receptor fragment. PMA stimulation of papain-treated cells increases uncleaved surface receptor on neutrophils by 400%, and on d-HL-60 by only 45%. This newly appearing receptor is the same apparent m.w. (55,000 to 75,000 for neutrophils; 62,000 to 80,000 for d-HL-60) and yields the same papain cleavage product (Mr, 31,000 for neutrophils; Mr, 29,000 for d-HL-60) as receptor on the surface of unstimulated cells. Formyl peptide receptor detected by affinity labeling in neutrophil specific granule-enriched subcellular fractions is identical to receptor found on the surface of unstimulated cells appearing as equal amounts of two isoelectric forms (isoelectric points, 5.8 and 6.2) at Mr 55,000 to 70,000. There is twice as much receptor present in the specific granule-enriched fraction per cell equivalent compared with plasma membrane. Azurophil granules contain trace amounts of receptor. Similar analysis of neutrophils treated with papain before subcellular fractionation shows that papain cleaved receptor fragment is detectable almost exclusively in the plasma membrane-enriched fraction. Most of the affinity-labeled formyl peptide receptor present in specific granule enriched fraction is present in membranes other than plasma membrane or Golgi membrane, because specific granule-enriched fraction contains only a small amount of plasma membrane marker and an amount of Golgi membrane marker equal to that found in plasma membrane-enriched fraction.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:3511145

Gardner, J P; Melnick, D A; Malech, H L

1986-02-15

212

Techniques For Focusing In Zone Electrophoresis  

NASA Technical Reports Server (NTRS)

In two techniques for focusing in zone electrophoresis, force of applied electrical field in each charged particle balanced by restoring force of electro-osmosis. Two techniques: velocity-gradient focusing (VGF), suitable for rectangular electrophoresis chambers; and field-gradient focusing (FGF), suitable for step-shaped electrophoresis chambers.

Sharnez, Rizwan; Twitty, Garland E.; Sammons, David W.

1994-01-01

213

Background electrolytes in 50% methanol\\/water for the determination of acidity constants of basic drugs by capillary zone electrophoresis  

Microsoft Academic Search

The acidic dissociation constants of several hydrophobic drugs, amiodarone and a series of antidepressants that show a secondary or tertiary amino group, were determined in a 50% methanol\\/water mixture by capillary zone electrophoresis. The electrophoretic behavior of buffers prepared from sodium acetate, tris(hydroxymethyl) aminomethane hydrochloride, sodium hydrogenphosphate, ammonium chloride, ethanolamine, butilammonium chloride, and sodium borate in the hydroalcoholic solution was

Vasco de Nogales; Rebeca Ruiz; Martí Rosés; Clara Ràfols; Elisabeth Bosch

2006-01-01

214

Acetate oxidation by syntrophic association between Geobacter sulfurreducens and a hydrogen-utilizing exoelectrogen  

PubMed Central

Anodic microbial communities in acetate-fed microbial fuel cells (MFCs) were analyzed using stable-isotope probing of 16S rRNA genes followed by denaturing gradient gel electrophoresis. The results revealed that Geobacter sulfurreducens and Hydrogenophaga sp. predominated in the anodic biofilm. Although the predominance of Geobacter sp. as acetoclastic exoelectrogens in acetate-fed MFC systems has been often reported, the ecophysiological role of Hydrogenophaga sp. is unknown. Therefore, we isolated and characterized a bacterium closely related to Hydrogenophaga sp. (designated strain AR20). The newly isolated strain AR20 could use molecular hydrogen (H2), but not acetate, with carbon electrode as the electron acceptor, indicating that the strain AR20 was a hydrogenotrophic exoelectrogen. This evidence raises a hypothesis that acetate was oxidized by G. sulfurreducens in syntrophic cooperation with the strain AR20 as a hydrogen-consuming partner in the acetate-fed MFC. To prove this hypothesis, G. sulfurreducens strain PCA was cocultivated with the strain AR20 in the acetate-fed MFC without any dissolved electron acceptors. In the coculture MFC of G. sulfurreducens and strain AR20, current generation and acetate degradation were the highest, and the growth of strain AR20 was observed. No current generation, acetate degradation and cell growth occurred in the strain AR20 pure culture MFC. These results show for the first time that G. sulfurreducens can oxidize acetate in syntrophic cooperation with the isolated Hydrogenophaga sp. strain AR20, with electrode as the electron acceptor.

Kimura, Zen-ichiro; Okabe, Satoshi

2013-01-01

215

Changes in Phospholipid Composition Studied by HPLC and Electric Properties of Liver Cell Membrane of Ethanol-Poisoned Rats  

PubMed Central

Ethanol introduced into the organism undergoes rapid metabolism to acetaldehyde and then to acetic acid. The process is accompanied by formation of reactive oxygen species (ROS), which damage mainly lipids of membrane cells. The effects of ROS can be neutralized by administering preparations with antioxidant properties. The natural preparations of this kind are teas. This paper reports data on the effect of green and black tea on the surface charge density, content of phospholipids, and level of lipid peroxidation products of liver cell membrane of rats chronically intoxicated with ethanol. Surface charge density of liver cells was measured by the electrophoresis method, whereas qualitative phospholipid composition was determined by the HPLC method. Ethanol administration caused an increase in the amount of all phospholipids, in surface charge density as well as in lipid peroxidation products. Ingestion of green and black tea with ethanol partially prevented these ethanol-induced changes, and the action of green tea was stronger than that of black tea.

Szachowicz-Petelska, Barbara; Dobrzynska, Izabela; Skrzydlewska, Elzbieta; Figaszewski, Zbigniew A.

2008-01-01

216

Studies on Cellulose Acetate Phthalate. 3. Osmotic Pressure Measurements  

Microsoft Academic Search

Osmotic pressure measurements of aqueous solutions of cellulose acetate phthalate (CAP) were carried out with the help of a highspeed membrane osmometer. The value of the osmotic coefficient, g, for different concentrations of CAP, as well as at different degree of neutralization for various concentrations, were estimated. The effect of concentration and degree of neutralization on the value of g

C. P. Patel; H. C. Trivedi; K. C. Patel; R. D. Patel

1986-01-01

217

Investigation on isobaric vapor liquid equilibrium for acetic acid + water + ( n-propyl acetate or iso-butyl acetate)  

Microsoft Academic Search

Isobaric vapor–liquid equilibrium (VLE) data for acetic acid+water, acetic acid+n-propyl acetate, acetic acid+iso-butyl acetate, acetic acid+water+n-propyl acetate, acetic acid+water+iso-butyl acetate are measured at 101.33kPa with a modified Rose still. The nonideal behavior in vapor phase caused by the association of acetic acid are corrected by the chemical theory and Hayden–O’Connell method, and analyzed by calculating the second virial coefficients and

Chundong Zhang; Hui Wan; Lijun Xue; Guofeng Guan

2011-01-01

218

Electrophoresis in strong electric fields.  

PubMed

Two kinds of non-linear electrophoresis (ef) that can be detected in strong electric fields (several hundred V/cm) are considered. The first ("classical" non-linear ef) is due to the interaction of the outer field with field-induced ionic charges in the electric double layer (EDL) under conditions, when field-induced variations of electrolyte concentration remain to be small comparatively to its equilibrium value. According to the Shilov theory, the non-linear component of the electrophoretic velocity for dielectric particles is proportional to the cubic power of the applied field strength (cubic electrophoresis) and to the second power of the particles radius; it is independent of the zeta-potential but is determined by the surface conductivity of particles. The second one, the so-called "superfast electrophoresis" is connected with the interaction of a strong outer field with a secondary diffuse layer of counterions (space charge) that is induced outside the primary (classical) diffuse EDL by the external field itself because of concentration polarization. The Dukhin-Mishchuk theory of "superfast electrophoresis" predicts quadratic dependence of the electrophoretic velocity of unipolar (ionically or electronically) conducting particles on the external field gradient and linear dependence on the particle's size in strong electric fields. These are in sharp contrast to the laws of classical electrophoresis (no dependence of V(ef) on the particle's size and linear dependence on the electric field gradient). A new method to measure the ef velocity of particles in strong electric fields is developed that is based on separation of the effects of sedimentation and electrophoresis using videoimaging and a new flowcell and use of short electric pulses. To test the "classical" non-linear electrophoresis, we have measured the ef velocity of non-conducting polystyrene, aluminium-oxide and (semiconductor) graphite particles as well as Saccharomice cerevisiae yeast cells as a function of the electric field strength, particle size, electrolyte concentration and the adsorbed polymer amount. It has been shown that the electrophoretic velocity of the particles/cells increases with field strength linearly up to about 100 and 200 V/cm (for cells) without and with adsorbed polymers both in pure water and in electrolyte solutions. In line with the theoretical predictions, in stronger fields substantial non-linear effects were recorded (V(ef)~E(3)). The ef velocity of unipolar ion-type conducting (ion-exchanger particles and fibres), electron-type conducting (magnesium and Mg/Al alloy) and semiconductor particles (graphite, activated carbon, pyrite, molybdenite) increases significantly with the electric field (V(ef)~E(2)) and the particle's size but is almost independent of the ionic strength. These trends are inconsistent with Smoluchowski's equation for dielectric particles, but are consistent with the Dukhin-Mishchuk theory of superfast electrophoresis. PMID:19041962

Barany, Sandor

2009-01-01

219

Capillary electrophoresis of natural products.  

PubMed

Capillary electrophoresis (CE) and micellar electrokinetic chromatography were used for the separation of widely different compounds from natural materials including antibiotics, humic substances, flavonoids, isoflavonoids, illicit drugs, coumarins, alkaloids, steroids, Chinese herbal preparations, nicotine, caffeine, amphetamines, toxins such as aflatoxins B1, B2, G1, G2, mycotoxins, heptapeptide toxins and others, ephedrine compounds, mineral elements, and natural compounds in biological samples. A discussion of sample extraction and clean-up and the advantages of using CE is also presented. PMID:9456058

Issaq, H J

1997-11-01

220

Capillary electrophoresis systems and methods  

DOEpatents

An embodiment of the invention is directed to a capillary electrophoresis apparatus comprising a plurality of separation micro-channels. A sample loading channel communicates with each of the plurality of separation channels. A driver circuit comprising a plurality of electrodes is configured to induce an electric field across each of the plurality of separation channels sufficient to cause analytes in the samples to migrate along each of the channels. The system further comprises a plurality of detectors configured to detect the analytes.

Dorairaj, Rathissh (Hillsboro, OR); Keynton, Robert S. (Louisville, KY); Roussel, Thomas J. (Louisville, KY); Crain, Mark M. (Georgetown, IN); Jackson, Douglas J. (New Albany, IN); Walsh, Kevin M. (Louisville, KY); Naber, John F. (Goshen, KY); Baldwin, Richard P. (Louisville, KY); Franco, Danielle B. (Mount Washington, KY)

2011-08-02

221

DNA Sequencing by Capillary Electrophoresis  

PubMed Central

Sequencing of human and other genomes has been at the center of interest in the biomedical field over the past several decades and is now leading toward an era of personalized medicine. During this time, DNA sequencing methods have evolved from the labor intensive slab gel electrophoresis, through automated multicapillary electrophoresis systems using fluorophore labeling with multispectral imaging, to the “next generation” technologies of cyclic array, hybridization based, nanopore and single molecule sequencing. Deciphering the genetic blueprint and follow-up confirmatory sequencing of Homo sapiens and other genomes was only possible by the advent of modern sequencing technologies that was a result of step by step advances with a contribution of academics, medical personnel and instrument companies. While next generation sequencing is moving ahead at break-neck speed, the multicapillary electrophoretic systems played an essential role in the sequencing of the Human Genome, the foundation of the field of genomics. In this prospective, we wish to overview the role of capillary electrophoresis in DNA sequencing based in part of several of our articles in this journal.

Karger, Barry L.; Guttman, Andras

2009-01-01

222

BIOCHEMICAL AND MORPHOLOGICAL COMPARISON OF PLASMA MEMBRANE AND MILK FAT GLOBULE MEMBRANE FROM BOVINE MAMMARY GLAND  

PubMed Central

Purified plasma membrane fractions from lactating bovine mammary glands and membranes of milk fat globules from the same source were similar in distribution and fatty acid composition of phospholipids. The sphingomyelin content of the phospholipid fraction of both membranes was higher than in these fractions from other cell components, ?-carotene, a constituent characteristic of milk fat, was present in the lipid fraction of the plasma membrane. Cholesterol esters of plasma membrane were similar in fatty acid composition to those of milk fat globule membranes. Disc electrophoresis of either membrane preparation on polyacrylamide gels revealed a single major protein component characteristic of plasma membrane from other sources. Distinct morphological differences between plasma membrane and milk fat globule membranes were observed in both thin sections and in negatively stained material. Plasma membrane was vesicular in appearance while milk fat globule membranes had a platelike aspect. These observations are consistent with derivation of fat globule membrane from plasma membrane accompanied by structural rearrangement of membrane constituents.

Keenan, T. W.; Morre, D. James; Olson, Diane E.; Yunghans, W. N.; Patton, Stuart

1970-01-01

223

High-resolution zone electrophoresis, combined with immunofixation, in the detection of an occult myeloma paraprotein.  

PubMed

A high-resolution agarose gel electrophoretic technique, coupled with immunofixation, was used to follow paraprotein concentrations retrospectively in a patient with multiple myeloma of nine years' duration. Although the patient's IgA lambda gammopathy "disappeared" shortly after the initiation of therapy, as judged by routine cellulose acetate electrophoresis and immunoelectrophoresis, high-resolution zone electrophoresis demonstrated a monoclonal band that we identified by immunofixation as the IgA lambda paraprotein. The combination of the two simple, inexpensive, and reliable techniques of high-resolution agarose electrophoresis and immunofixation thereby permitted detection and identification of a myeloma protein in a patient otherwise thought to be in complete remission. We believe this approach is useful in assessing persistent or recurrent disease in patients with a known history of myeloma; this combination of techniques may also prove beneficial in the early diagnosis of multiple myeloma. PMID:7127781

Reichert, C M; Everett, D F; Nadler, P I; Papadopoulos, N M

1982-11-01

224

Hydrocasting Reverse Osmosis Membranes, Development of Porous Support Tubes, Study of the Mechanism of Membrane Formation and Development of Non-Cellulosic Desalination Membranes.  

National Technical Information Service (NTIS)

The report discusses the results from on going research on hydrocasting cellulose acetate membranes in porous support tubes and porous tubes development, characterization of cellulosic and non cellulosic membrane tubules hydrocast in solid tubes, radii op...

A. Gollan M. Frommer R. Matz M. Tulin

1973-01-01

225

[Nomegestrol acetate: clinical pharmacology].  

PubMed

Progestogens are used in clinical practice in some conditions. Their effects depend on their chemical structure, pharmacokinetics, pharmacodynamics, with important differences among various progestogens. Generally, progestins are classified according to their parent molecule, of which often they keep some features. Derivatives of 19-nor-progesterone are characterized by high selectivity of action on progestin receptor. In particular, nomegestrol acetate (NomAc) shows an important progestational potency, neutral gluco-lipid profile, and antigonadotropic activity. It is used for treating menstrual cycle disorders and for hormone replacement therapy in menopause in association with an estrogen. In future, thanks to its antigonadotropic activity, NomAc will be used in estroprogestin combinations in fertile women, thus taking advantage of its tolerability profile and obtaining numerous non-contraceptive benefits as well. PMID:19749678

Lello, S

2009-10-01

226

Effect of surface roughness of hollow fiber membranes with gear-shaped structure on membrane fouling by sodium alginate  

Microsoft Academic Search

In this work, the relationship between surface roughness of the membrane and membrane fouling was investigated with sodium alginate which is a kind of extracellular polymeric substances (EPS) and is regarded as a main foulant in membrane bioreactor (MBR). Cellulose acetate butyrate polymer which is superior in heat-resistance and mechanical strength was used as membrane material. The membranes having the

Masatoshi Hashino; Takeshi Katagiri; Noboru Kubota; Yoshikage Ohmukai; Tatsuo Maruyama; Hideto Matsuyama

2011-01-01

227

Membranes and Films from Polymers.  

ERIC Educational Resources Information Center

Provides background information on polymeric films and membranes including production methods, special industrial and medical applications, laboratory preparation, and an experimental investigation of a porous cellulose acetate membrane. Presents a demonstration to distinguish between high- and low-density polyethylene. (JM)

Blumberg, Avrom A.

1986-01-01

228

Thermogravimetric analysis of the relationship among calcium magnesium acetate, calcium acetate and magnesium acetate  

Microsoft Academic Search

Thermal decomposition characteristic of calcium magnesium acetate (CMA), calcium acetate (CA) and magnesium acetate (MA) are investigated through thermogravimetric (TG) analysis at the heating rates of 5Kmin?1, 7.5Kmin?1, 10Kmin?1 and 15Kmin?1. After dehydration, the evaporation of carboxylic radical and carbon dioxide of CMA and CA exist in two separate segments, but for MA, this occurs together in just one segment

Shengli Niu; Kuihua Han; Chunmei Lu; Rongyue Sun

2010-01-01

229

Membrane humidity control investigation  

NASA Technical Reports Server (NTRS)

The basic performance data on a hollow fiber membrane unit that removes water from a breathing gas loop by diffusion is presented. Using available permeability data for cellulose acetate, a preliminary design was made of a dehumidifier unit that would meet the problem statement.

Elam, J.; Ruder, J.; Strumpf, H.

1974-01-01

230

Stabilized Calcium Acetate Oil Dispersions.  

National Technical Information Service (NTIS)

A lubricating composition is imparted with improved load-carrying ability and anti-wear properties by incorporation of calcium acetate. The composition consists of a base lubricant, 0.1 to 50 percent by weight calcium acetate and 0.01 to 20 percent by wei...

R. H. Davis

1965-01-01

231

[Formulation of calcium acetate tablets].  

PubMed

The results of the testing of calcium acetate tablets, produced by direct compression and by wet granulation (Ph. Jug. IV) are presented. Tablet hardness, friability and disintegration were determined. The best properties were observed in the tablets produced with maize starch. This procedure is fast and simple, and compound tablets of calcium acetate fulfill the current requirements for this type of preparation. PMID:11521467

Obrenovic, D; Gazikalovic, E; Ognjanovic, J; Nidzovic Z, Z

2000-01-01

232

Integrated multiplexed capillary electrophoresis system  

DOEpatents

The present invention provides an integrated multiplexed capillary electrophoresis system for the analysis of sample analytes. The system integrates and automates multiple components, such as chromatographic columns and separation capillaries, and further provides a detector for the detection of analytes eluting from the separation capillaries. The system employs multiplexed freeze/thaw valves to manage fluid flow and sample movement. The system is computer controlled and is capable of processing samples through reaction, purification, denaturation, pre-concentration, injection, separation and detection in parallel fashion. Methods employing the system of the invention are also provided.

Yeung, Edward S. (Ames, IA); Tan, Hongdong (Ames, IA)

2002-05-14

233

Denaturing gradient gel electrophoresis (DGGE).  

PubMed

Denaturing Gradient Gel Electrophoresis (DGGE) is a technique used to separate short- to medium-length DNA fragments based on their melting characteristics. It has been used frequently for identifying single-nucleotide polymorphisms without the need for DNA sequencing and as a molecular fingerprinting method for complex ecosystem communities, in particular in conjunction with amplification of microbial 16S rRNA genes. Here, the principles of DGGE, based on partial DNA strand separation at a given position in a gradient of chemical denaturant, are described, and an example protocol, optimized for fingerprinting of 200-300 bp fragments of bacterial 16S rRNA genes, is given. PMID:23913290

Strathdee, Fiona; Free, Andrew

2013-01-01

234

Electromigration dispersion in Capillary Electrophoresis  

PubMed Central

In a previous paper (S. Ghosal and Z. Chen Bull. Math. Biol. 2010 72, pg. 2047) it was shown that the evolution of the solute concentration in capillary electrophoresis is described by a nonlinear wave equation that reduced to Burger’s equation if the nonlinearity was weak. It was assumed that only strong electrolytes (fully dissociated) were present. In the present paper it is shown that the same governing equation also describes the situation where the electrolytic buffer consists of a single weak acid (or base). A simple approximate formula is derived for the dimensionless peak variance which is shown to agree well with published experimental data.

Chen, Zhen; Ghosal, Sandip

2012-01-01

235

Molecular Structure of Phenylmercuric acetate  

NSDL National Science Digital Library

Phenylmercuric acetate is white to white-yellow crystalline powder that is odorless. This phenyl mercury compound is used mainly as a fungicide, herbicide, slimicide and bacteriocide. Phenylmercuric acid serves as a preservative in canned paint, eye ointments and drops, injectable solutions, skin disinfectants and in cosmetics products such as hair shampoos, mouthwashes and toothpastes. It is also used in contraceptive gels and foams. Phenylmercuric acetate is prepared by interaction of benzene with mercuric acetate in glacial acetic acid. Phenylmercuric acetate's former production and use as a fungicide and as a mildew inhibitor in paints may have resulted in its direct release to the environment. This substance is very toxic to aquatic organisms and may be hazardous to the environment.

2004-11-10

236

Development of a New Concept in Membrane Structure for Application in Hemodialysis.  

National Technical Information Service (NTIS)

The objective of this program was to develop ultrathin membranes that would exhibit superior transport properties when compared to conventional cellulose membranes. A new, high permeability ultrathin cellulose membrane derived from cellulose acetate has b...

L. T. Rozelle R. J. Petersen

1974-01-01

237

DNA electrophoresis in a monodisperse porous medium  

NASA Astrophysics Data System (ADS)

Electrophoresis of DNA migrating in an ordered matrix is studied and compared with classical agarose gel electrophoresis. A well-defined migration medium is obtained by crystallization of monodisperse silica spheres. Electrophoretic mobility of DNA is measured with fluorescence recovery after photobleaching experiments. The main result is that, as it was the case for gel electrophoresis, diffusion and electrophoretic mobility of DNA in such a medium are well described with reptation theories.

Meistermann, L.; Tinland, B.

2000-09-01

238

Characterization of Carbohydrates Using Highly Fluorescent 2-Aminobenzoic Acid Tag Following Gel Electrophoresis of Glycoproteins  

Microsoft Academic Search

Application of the most sensitive fluorescent label 2-aminobenzoic acid (anthranilic acid, AA) for characterization of carbohydrates from the glycoproteins (?15 pmol) separated by polyacrylamide gel electrophoresis is described. AA label is used for the determination of both monosaccharide composition and oligosaccharide map. For the monosaccharide determination, bands containing the glycoprotein of interest are excised from the polyvinylidene fluoride (PVDF) membrane

Kalyan R. Anumula; Ping Du

1999-01-01

239

Charge Shift Electrophoresis: Simple Method for Distinguishing between Amphiphilic and Hydrophilic Proteins in Detergent Solution  

Microsoft Academic Search

Seventeen hydrophilic proteins and five amphiphilic membrane proteins were subjected to agarose gel electrophoresis in the presence of a nonionic detergent (Triton X-100), a mixture of a nonionic and an anionic detergent (Triton X-100 and sodium deoxycholate), and a mixture of a nonionic and a cationic detergent (Triton X-100 and cetyltrimethylammonium bromide). The electrophoretic mobility of the hydrophilic proteins was

Ari Helenius; Kai Simons

1977-01-01

240

Transient electrophoresis of dielectric spheres.  

PubMed

The dynamic electrophoretic response of a spherical dielectric particle suspended in an electrolyte solution to a step change in the applied electrics field is analytically studied. The electrical double layer surrounding the particle may have either a small but finite thickness or a very large thickness relative to the particle radius. For the case of electrophoresis of a particle with a thin double layer, the local electroosmotic velocity at the outer edge of the double layer evolving with time after the external field is imposed is used as an apparent slip boundary condition at the particle surface so that the unsteady equation of motion for the fluid flow outside the double layer is solved. Closed-form formulas for the transient electrophoretic mobility of the particle are derived as functions of relevant parameters. The results demonstrate that, when the double layer surrounding the particle is relatively thin, the normalized electrophoretic mobility at a given dimensionless time decreases monotonically with a decrease in the parameter kappaa, where kappa(-1) is the Debye screening length and a is the particle radius. When the double layer of the particle is relatively thick, the particle mobility can have magnitudes comparable to those for a particle with a thin double layer in the initial stage, but will become much smaller afterward. In general, the effect of the relaxation time for transient electrophoresis is negligible, regardless of the value of kappaa. PMID:15990107

Keh, Huan J; Huang, You C

2005-11-01

241

Capillary electrophoresis for drug analysis  

NASA Astrophysics Data System (ADS)

Capillary electrophoresis (CE) is a high resolution separation technique which is amenable to a wide variety of solutes, including compounds which are thermally degradable, non-volatile and highly polar, and is therefore well suited for drug analysis. Techniques which have been used in our laboratory include electrokinetic chromatography (ECC), free zone electrophoresis (CZE) and capillary electrochromatography (CEC). ECC, which uses a charged run buffer additive which migrates counter to osmotic flow, is excellent for many applications, including, drug screening and analyses of heroin, cocaine and methamphetamine samples. ECC approaches include the use of micelles and charged cyclodextrins, which allow for the separation of complex mixtures. Simultaneous separation of acidic, neutral and basic solutes and the resolution of optical isomers and positional isomers are possible. CZE has been used for the analysis of small ions (cations and anions) in heroin exhibits. For the ECC and CZE experiments performed in our laboratory, uncoated capillaries were used. In contrast, CEC uses capillaries packed with high performance liquid chromatography stationary phases, and offers both high peak capacities and unique selectivities. Applications include the analysis of cannabinoids and drug screening. Although CE suffers from limited concentration sensitivity, it is still applicable to trace analysis of drug samples, especially when using injection techniques such as stacking, or detection schemes such as laser induced fluorescence and extended pathlength UV.

Lurie, Ira S.

1999-02-01

242

Triamcinolone acetonide acetate.  

PubMed

IN THE CRYSTAL STRUCTURE OF THE TITLE COMPOUND [SYSTEMATIC NAME: 2-(4b-fluoro-5-hy-droxy-4a,6a,8,8-tetra-methyl-2-oxo-2,4a,4b,5,6,6a,9a,10,10a,10b,11,12-dodeca-hydro-7,9-dioxa-penta-leno[2,1-a]phenanthren-6b-yl)-2-oxoethyl acetate], C(26)H(33)FO(7), the mol-ecules are connected by inter-molecular O-H?O hydrogen bonds into an infinite supra-molecular chain along the b axis. The mol-ecular framework consists of five condensed rings, including three six-membered rings and two five-membered rings. The cyclo-hexa-2,5-dienone ring is nearly planar [maximum deviation = 0.013?(3)?Å], while the cyclo-hexane rings adopt chair conformations. The two five-membered rings, viz. cyclo-pentane and 1,3-dioxolane, display envelope conformations. PMID:21523039

Lu, Xiao; Tang, Gu-Ping; Gu, Jian-Ming; Hu, Xiu-Rong

2011-01-01

243

Triamcinolone acetonide acetate  

PubMed Central

In the crystal structure of the title compound [systematic name: 2-(4b-fluoro-5-hy­droxy-4a,6a,8,8-tetra­methyl-2-oxo-2,4a,4b,5,6,6a,9a,10,10a,10b,11,12-dodeca­hydro-7,9-dioxa­penta­leno[2,1-a]phenanthren-6b-yl)-2-oxoethyl acetate], C26H33FO7, the mol­ecules are connected by inter­molecular O—H?O hydrogen bonds into an infinite supra­molecular chain along the b axis. The mol­ecular framework consists of five condensed rings, including three six-membered rings and two five-membered rings. The cyclo­hexa-2,5-dienone ring is nearly planar [maximum deviation = 0.013?(3)?Å], while the cyclo­hexane rings adopt chair conformations. The two five-membered rings, viz. cyclo­pentane and 1,3-dioxolane, display envelope conformations.

Lu, Xiao; Tang, Gu-Ping; Gu, Jian-Ming; Hu, Xiu-Rong

2011-01-01

244

Conducting polymer electrodes for gel electrophoresis.  

PubMed

In nearly all cases, electrophoresis in gels is driven via the electrolysis of water at the electrodes, where the process consumes water and produces electrochemical by-products. We have previously demonstrated that ?-conjugated polymers such as poly(3,4-ethylenedioxythiophene) (PEDOT) can be placed between traditional metal electrodes and an electrolyte to mitigate electrolysis in liquid (capillary electroosmosis/electrophoresis) systems. In this report, we extend our previous result to gel electrophoresis, and show that electrodes containing PEDOT can be used with a commercial polyacrylamide gel electrophoresis system with minimal impact to the resulting gel image or the ionic transport measured during a separation. PMID:24586761

Bengtsson, Katarina; Nilsson, Sara; Robinson, Nathaniel D

2014-01-01

245

DNA Sequencing Using capillary Electrophoresis  

SciTech Connect

The overall goal of this program was to develop capillary electrophoresis as the tool to be used to sequence for the first time the Human Genome. Our program was part of the Human Genome Project. In this work, we were highly successful and the replaceable polymer we developed, linear polyacrylamide, was used by the DOE sequencing lab in California to sequence a significant portion of the human genome using the MegaBase multiple capillary array electrophoresis instrument. In this final report, we summarize our efforts and success. We began our work by separating by capillary electrophoresis double strand oligonucleotides using cross-linked polyacrylamide gels in fused silica capillaries. This work showed the potential of the methodology. However, preparation of such cross-linked gel capillaries was difficult with poor reproducibility, and even more important, the columns were not very stable. We improved stability by using non-cross linked linear polyacrylamide. Here, the entangled linear chains could move when osmotic pressure (e.g. sample injection) was imposed on the polymer matrix. This relaxation of the polymer dissipated the stress in the column. Our next advance was to use significantly lower concentrations of the linear polyacrylamide that the polymer could be automatically blown out after each run and replaced with fresh linear polymer solution. In this way, a new column was available for each analytical run. Finally, while testing many linear polymers, we selected linear polyacrylamide as the best matrix as it was the most hydrophilic polymer available. Under our DOE program, we demonstrated initially the success of the linear polyacrylamide to separate double strand DNA. We note that the method is used even today to assay purity of double stranded DNA fragments. Our focus, of course, was on the separation of single stranded DNA for sequencing purposes. In one paper, we demonstrated the success of our approach in sequencing up to 500 bases. Other application papers of sequencing up to this level were also published in the mid 1990's. A major interest of the sequencing community has always been read length. The longer the sequence read per run the more efficient the process as well as the ability to read repeat sequences. We therefore devoted a great deal of time to studying the factors influencing read length in capillary electrophoresis, including polymer type and molecule weight, capillary column temperature, applied electric field, etc. In our initial optimization, we were able to demonstrate, for the first time, the sequencing of over 1000 bases with 90% accuracy. The run required 80 minutes for separation. Sequencing of 1000 bases per column was next demonstrated on a multiple capillary instrument. Our studies revealed that linear polyacrylamide produced the longest read lengths because the hydrophilic single strand DNA had minimal interaction with the very hydrophilic linear polyacrylamide. Any interaction of the DNA with the polymer would lead to broader peaks and lower read length. Another important parameter was the molecular weight of the linear chains. High molecular weight (> 1 MDA) was important to allow the long single strand DNA to reptate through the entangled polymer matrix. In an important paper, we showed an inverse emulsion method to prepare reproducibility linear polyacrylamide polymer with an average MWT of 9MDa. This approach was used in the polymer for sequencing the human genome. Another critical factor in the successful use of capillary electrophoresis for sequencing was the sample preparation method. In the Sanger sequencing reaction, high concentration of salts and dideoxynucleotide remained. Since the sample was introduced to the capillary column by electrokinetic injection, these salt ions would be favorably injected into the column over the sequencing fragments, thus reducing the signal for longer fragments and hence reading read length. In two papers, we examined the role of individual components from the sequencing reaction and then developed a protocol to reduce the deleterio

Dr. Barry Karger

2011-05-09

246

Regulation of membrane associated protein kinase C activity by guanine nucleotide in rabbit peritoneal neutrophils  

SciTech Connect

Addition of phorbol myristate acetate (PMA) (0.1 ..mu..g/ml) or guanosine-5'-0-(3-thiotriphosphate) (GTP..gamma..S) (10..mu..M) to the membrane fraction from rabbit peritoneal neutrophils results in an increase of phosphorylation of several membrane proteins. To test whether membrane associated protein kinase C is involved in the activation, histone is added to the membrane as a substrate for protein kinase C. Phosphorylation of histone is determined by counting the gel pieces containing histone IIIS after separation from other membrane components by SDS-gel electrophoresis. In the presence of CaC12 (20 ..mu..M), GTP..gamma..S (10 ..mu..M) or PMA (0.1 ..mu..g/ml) stimulates the phosphorylation of histone IIIS (40% to 70% increase). To achieve this effect calcium is required for GTP..gamma..S but not for PMA. The effect of GTP..gamma..S but not PMA is inhibited in membranes obtained from cells pretreated with pertussis toxin. Membrane protein kinase C is solubilized with Triton X-100 (1%) and then applied to a DEAE-52 cellulose column chromatography. Two peaks of protein kinase C activity are observed. Peak one is eluted at 40 mM NaCl, peak two is eluted at 140 mM NaCl. The activity of peak one is stimulated with phosphatidylserine (PS) and PMA but not with PS and calcium. The activity of peak two is stimulated with either PS and PMA or PS and calcium. The results suggest that GTP binding protein is involved in the activation of membrane associated protein kinase C and the kinase may exist in two forms, calcium sensitive and calcium insensitive.

Huang, C.K.; Devanney, J.F.

1986-03-05

247

Dichloroaniline retention by nanofiltration membranes.  

PubMed

This study evaluates the performance of two nanofiltration membranes in removing a herbicide: dichloroaniline. The membranes, one polyamide and one cellulose acetate, have a cut-off in the range 150-300 g/mol (manufacturers' data). The experiments were carried out with solutions of dichloroaniline in demineralized water, with concentrations from 1 to 10 ppb. For each membrane, the amount of herbicide retained and adsorbed by the membrane was determined as a function of feed concentration and transmembrane pressure. The two membranes, made of different materials but having the same nominal cut-off, retained dichloroaniline to very different extents and by different mechanisms. PMID:15878032

Causserand, C; Aimar, P; Cravedi, J P; Singlande, E

2005-04-01

248

Molecular Structure of Sodium acetate  

NSDL National Science Digital Library

Sodium acetate is known for its ability to supercool. It freezes at 130 degrees, but can exist as a liquid at a much lower temperature. In order to melt solidified sodium acetate, however, every single crystal must liquify, otherwise the material will recrystallize. Sodium acetate has been used as a deicer for roads and runways. It is also used a component of buffer systems and in the manufacture of pharmaceuticals and heat pads. The compound is quite stable. It may act as an irritant and be harmful if inhaled or absorbed through the skin.

2002-08-26

249

Electrophoresis-mass spectrometry probe  

DOEpatents

The invention involves a new technique for the separation of complex mixtures of chemicals, which utilizes a unique interface probe for conventional mass spectrometers which allows the electrophoretically separated compounds to be analyzed in real-time by a mass spectrometer. This new chemical analysis interface, which couples electrophoresis with mass spectrometry, allows complex mixtures to be analyzed very rapidly, with much greater specificity, and with greater sensitivity. The interface or probe provides a means whereby large and/or polar molecules in complex mixtures to be completely characterized. The preferred embodiment of the probe utilizes a double capillary tip which allows the probe tip to be continually wetted by the buffer, which provides for increased heat dissipation, and results in a continually operating interface which is more durable and electronically stable than the illustrated single capillary tip probe interface.

Andresen, Brian D. (Pleasanton, CA); Fought, Eric R. (Livermore, CA)

1987-01-01

250

Electrophoresis-mass spectrometry probe  

DOEpatents

The invention involves a new technique for the separation of complex mixtures of chemicals, which utilizes a unique interface probe for conventional mass spectrometers which allows the electrophoretically separated compounds to be analyzed in real-time by a mass spectrometer. This new chemical analysis interface, which couples electrophoresis with mass spectrometry, allows complex mixtures to be analyzed very rapidly, with much greater specificity, and with greater sensitivity. The interface or probe provides a means whereby large and/or polar molecules in complex mixtures to be completely characterized. The preferred embodiment of the probe utilizes a double capillary tip which allows the probe tip to be continually wetted by the buffer, which provides for increased heat dissipation, and results in a continually operating interface which is more durable and electronically stable than the illustrated single capillary tip probe interface. 8 figs.

Andresen, B.D.; Fought, E.R.

1987-11-10

251

Combined sorption\\/transport of sodium dodecyl sulfate and hydrochloric acid in a blend of cellulose acetate butyrate with cellulose acetate hydrogen phthalate  

Microsoft Academic Search

The transport of hydrochloric acid (0.001–0.1 M) and sodium dodecyl sulfate (0.001–0.1 M) has been measured through a membrane consisting of a blend of cellulose acetate butyrate and cellulose acetate hydrogen phthalate. The cellulose derivative blend is suggested to suffer an alteration in the degree of hydrophobicity when in equilibrium with sodium dodecyl sulfate (SDS) through hemimicelle formation. An increase

Artur J. M. Valente; Hugh D. Burrows; Alexandre Ya. Polishchuk; Maria G. Miguel; Victor M. M. Lobo

2004-01-01

252

Fluorescence detection for gel and capillary electrophoresis  

SciTech Connect

First, an indirect fluorescence detection system for the separation of proteins via gel electrophoresis. Quantities as low as 50 nanograms of bovine serum albumin and soybean trypsin inhibitor are separated and detected visually without the need for staining of the analytes. This is very similar to levels of protein commonly separated with gel electrophoresis.

Hogan, B.

1992-07-21

253

Getting the Most out of Electrophoresis Units  

ERIC Educational Resources Information Center

At Oklahoma City Community College, they have developed gel electrophoresis activities that support active learning of many scientific concepts, including: pH, electrolysis, oxidation reduction, electrical currents, potentials, conductivity, molarity, gel electrophoresis, DNA and protein separation, and DNA fingerprinting. This article presents…

Mulvihill, Charlotte

2007-01-01

254

Compensating for Electro-Osmosis in Electrophoresis  

NASA Technical Reports Server (NTRS)

Simple mechanical adjustment eliminates transverse velocity component. New apparatus for moving-wall electrophoresis increases degree of collimation of chemical species in sample stream. Electrophoresis chamber set at slight angle in horizontal plane to adjust angle between solution flow and wall motion. Component of velocity created cancels electro-osmotic effect.

Rhodes, Percy H.; Snyder, Robert S.

1987-01-01

255

Acetate catabolism by Methanosarcina barkeri  

SciTech Connect

Cell suspensions of Methanosarcina barkeri convert the carboxyl and methyl group carbons of acetate to carbon dioxide and methane at pH 6 under an atmosphere of 100% CO/sub 2/. The rate of loss of radioactivity from (1-/sup 14/C)acetate was over three times greater than that from (2-/sup 14/C)acetate under these conditions. Control experiments with both labeled substrates present showed that the rates were additive. Addition of a high level of 2-bromoethanesulfonate to selectively inhibit methane formation largely inhibited release of /sup 14/C from methyl-labeled acetate but only marginally decreased the rate of loss from (1-/sup 14/C)acetate. Thus, in the absence of the inhibitor loss of /sup 14/C from (1-/sup 14/C)acetate likely reflects an isotopic exchange reaction with CO/sub 2/ superimposed on the overall conversion of acetate to CO/sub 2/ and CH/sub 4/. The exchange reaction was inhibited by uncouplers such as 2,4-dinitrophenol, CCCP, and FCCP. Cells permeabilized by treatment with nonionic detergents or disrupted by passage through a French pressure cell failed to catalyze the exchange reaction. Exchange activity was not restored by addition of ATP or by use of (1-/sup 14/C)acetyl CoA as substrate. No evidence for involvement of carbon monoxide dehydrogenase in the exchange was found in these experiments when CO/sub 2/ was replaced by CO. However, the soluble extracts retained the ability to convert acetate to methane in the presence of H/sub 2/ and ATP.

Grahame, D.A.

1987-05-01

256

Two Electrophoresis Experiments for Freshmen in the Health Professions.  

ERIC Educational Resources Information Center

Describes procedures involved with paper electrophoresis separation of amino acids, gel electrophoresis separation of DNA, and design of an electrophoresis tank. Describes experiments using paper (amino acids) and gel (deoxyribonucleic acid fragments). Provides material lists, procedures, and discussion. (JM)

Brabson, G. Dana; Waugh, David S.

1986-01-01

257

Phorbol myristate acetate receptors in human polymorphonuclear neutrophils  

Microsoft Academic Search

Resting or phorbol myristate acetate (PMA)-pretreated neutrophils were disrupted by nitrogen cavitation and were fractionated on Percoll density gradients to identify the subcellular location of PMA receptors. Receptors were found in the cytoplasm of resting cells; neither primary nor secondary granules bound (³H)PMA, and the few binding sites located in non-granule membrane fractions appeared to reflect cytosolic contamination. Contrastingly, PMA-pretreated

J. Nishihira; J. T. OFlaherty

1985-01-01

258

Hydrolysis of ethyl acetate:a pervaporation study  

Microsoft Academic Search

The influence of temperature on the separation factor, diffusion process, permeation rate, and permeability coefficient (k) for hydrolysis of ethyl acetate using a standard poly(vinyl alcohol) (PVA) membrane by pervaporation was investigated. The preliminary data presented in this work was obtained using a simple pervaporation technique built in-house. The experiments were conducted at 80, 65, 50 and 35°C. The initial

Habib I. Shaban

1998-01-01

259

Investigation on isobaric vapor–liquid equilibrium for acetic acid + water + methyl ethyl ketone + isopropyl acetate  

Microsoft Academic Search

Isobaric vapor–liquid equilibrium (VLE) data for acetic acid+water, acetic acid+methyl ethyl ketone (MEK), MEK+isopropyl acetate, acetic acid+MEK+water and acetic acid+MEK+isopropyl acetate+water are measured at 101.33kPa using a modified Rose cell. The nonideal behavior in vapor phase of binary systems measured in this work is analyzed through calculating fugacity coefficients since mixture containing acetic acid deviates from ideal behavior seriously in

Qiang Xie; Hui Wan; MingJuan Han; GuoFeng Guan

2009-01-01

260

Improved Isolation Procedures for the Purple Membrane of Halobacterium Halobium  

Microsoft Academic Search

Techniques for purifying the purple membrane of Halobacterium halobium are given. This purple membrane contains a chromoprotein with a retinal prosthetic group similar to rhodopsin, the chromoprotein found in the visual systems of higher invertebrates and vertebrates. The described purple membrane isolation procedures yield a highly purified preparation as determined by transmitting electron microscopy and gel electrophoresis. Critical analysis of

Brian M. Becher; Seph Y. Cassim

1975-01-01

261

The effect of CA membrane properties on adsorptive fouling by humic acid  

Microsoft Academic Search

Cellulose acetate membranes with varied charge, hydrophobicity, porosity, and pore size have been developed by annealing, hydrolysis and oxidation of a basic cellulose acetate membrane. The effects of these modifications were characterized by poly(ethylene glycol) retention, contact angle and streaming potential measurements, and atomic force microscopy. The behavior of the membranes during humic acid adsorption experiments has also been studied.

C Combe; E Molis; P Lucas; R Riley; M. M Clark

1999-01-01

262

Intracellular Reactions in Single Human Granulocytes upon Phorbol Myristate Acetate Activation using Confocal Raman Microspectroscopy  

Microsoft Academic Search

We have obtained new evidence for the occurrence of intracellular NADPH-oxidase activity in neutrophilic and eosinophilic granulocytes upon stimulation with phorbol myristate acetate (PMA). PMA activation leads to a partial translocation of cytochrome b558 from the membranes of the specific granules to the plasma membrane. It was suggested that NADPH-oxidase activity only takes place in the plasma membrane, leading to

Nanna M. Sijtsema; Arjan G. J. Tibbe; Ine G. M. J. Segers-Nolten; Arthur J. Verhoeven; Ron S. Weening; Jan Greve; Cees Otto

2000-01-01

263

Rapid and simple pretreatment of human body fluids using electromembrane extraction across supported liquid membrane for capillary electrophoretic determination of lithium.  

PubMed

Electromembrane extraction was used for simultaneous sample cleanup and preconcentration of lithium from untreated human body fluids. The sample of a body fluid was diluted 100 times with 0.5 mM Tris solution and lithium was extracted by electromigration through a supported liquid membrane composed of 1-octanol into 100 mM acetic acid acceptor solution. Matrix compounds, such as proteins, red blood cells, and other high-molecular-weight compounds were efficiently retained on the supported liquid membrane. The liquid membrane was anchored in pores of a short segment of a polypropylene hollow fiber, which represented a low cost, single use, disposable extraction unit and was discarded after each use. Acceptor solutions were analyzed using capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C(4) D) and baseline separation of lithium was achieved in a background electrolyte solution consisting of 18 mM L-histidine and 40 mM acetic acid at pH 4.6. Repeatability of the electromembrane extraction-CE-C(4) D method was evaluated for the determination of lithium in standard solutions and real samples and was better than 0.6 and 8.2% for migration times and peak areas, respectively. The concentration limit of detection of 9 nM was achieved. The developed method was applied to the determination of lithium in urine, blood serum, blood plasma, and whole blood at both endogenous and therapeutic concentration levels. PMID:21500213

Strieglerová, Lenka; Kubá?, Pavel; Bo?ek, Petr

2011-05-01

264

Nonlinear waves in capillary electrophoresis  

PubMed Central

Electrophoretic separation of a mixture of chemical species is a fundamental technique of great usefulness in biology, health care and forensics. In capillary electrophoresis the sample migrates in a microcapillary in the presence of a background electrolyte. When the ionic concentration of the sample is sufficiently high, the signal is known to exhibit features reminiscent of nonlinear waves including sharp concentration ‘shocks’. In this paper we consider a simplified model consisting of a single sample ion and a background electrolyte consisting of a single co-ion and a counterion in the absence of any processes that might change the ionization states of the constituents. If the ionic diffusivities are assumed to be the same for all constituents the concentration of sample ion is shown to obey a one dimensional advection diffusion equation with a concentration dependent advection velocity. If the analyte concentration is sufficiently low in a suitable non-dimensional sense, Burgers’ equation is recovered, and thus, the time dependent problem is exactly solvable with arbitrary initial conditions. In the case of small diffusivity either a leading edge or trailing edge shock is formed depending on the electrophoretic mobility of the sample ion relative to the background ions. Analytical formulas are presented for the shape, width and migration velocity of the sample peak and it is shown that axial dispersion at long times may be characterized by an effective diffusivity that is exactly calculated. These results are consistent with known observations from physical and numerical simulation experiments.

Ghosal, Sandip; Chen, Zhen

2011-01-01

265

Acetate and Formate Stress: Opposite Responses in the Proteome of Escherichia coli  

PubMed Central

Acetate and formate are major fermentation products of Escherichia coli. Below pH 7, the balance shifts to lactate; an oversupply of acetate or formate retards growth. E. coli W3110 was grown with aeration in potassium-modified Luria broth buffered at pH 6.7 in the presence or absence of added acetate or formate, and the protein profiles were compared by two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Acetate increased the steady-state expression levels of 37 proteins, including periplasmic transporters for amino acids and peptides (ArtI, FliY, OppA, and ProX), metabolic enzymes (YfiD and GatY), the RpoS growth phase regulon, and the autoinducer synthesis protein LuxS. Acetate repressed 17 proteins, among them phosphotransferase (Pta). An ackA-pta deletion, which nearly eliminates interconversion between acetate and acetyl-coenzyme A (acetyl-CoA), led to elevated basal levels of 16 of the acetate-inducible proteins, including the RpoS regulon. Consistent with RpoS activation, the ackA-pta strain also showed constitutive extreme-acid resistance. Formate, however, repressed 10 of the acetate-inducible proteins, including the RpoS regulon. Ten of the proteins with elevated basal levels in the ackA-pta strain were repressed by growth of the mutant with formate; thus, the formate response took precedence over the loss of the ackA-pta pathway. The similar effects of exogenous acetate and the ackA-pta deletion, and the opposite effect of formate, could have several causes; one possibility is that the excess buildup of acetyl-CoA upregulates stress proteins but excess formate depletes acetyl-CoA and downregulates these proteins.

Kirkpatrick, Christopher; Maurer, Lisa M.; Oyelakin, Nikki E.; Yoncheva, Yuliya N.; Maurer, Russell; Slonczewski, Joan L.

2001-01-01

266

Biodegradable cellulose acetate nanofiber fabrication via electrospinning.  

PubMed

Nanofiber manufacturing is one of the key advancements in nanotechnology today. Over the past few years, there has been a tremendous growth of research activities to explore electrospinning for nanofiber formation from a rich variety of materials. This quite simple and cost effective process operates on the principle that the solution is extracted under the action of a high electric field. Once the voltage is sufficiently high, a charged jet is ejected following a complicated looping trajectory. During its travel, the solvent evaporates leaving behind randomly oriented nanofibers accumulated on the collector. The combination of their nanoscale dimensionality, high surface area, porosity, flexibility and superior strength makes the electrospun fibers suitable for several value-added applications, such as filters, protecting clothes, high performance structures and biomedical devices. In this study biodegradable cellulose acetate (CA) nanofibrous membranes were produced using electrospinning. The device utilized consisted of a syringe equipped with a metal needle, a microdialysis pump, a high voltage supply and a collector. The morphology of the yielded fibers was determined using SEM. The effect of various parameters, including electric field strength, tip-to-collector distance, solution feed rate and composition on the morphological features of the electrospun fibers was examined. The optimum operating conditions for the production of uniform, non-beaded fibers with submicron diameter were also explored. The biodegradable CA nanofiber membranes are suitable as tissue engineering scaffolds and as reinforcements of biopolymer matrix composites in foils by ultrasonic welding methods. PMID:21133179

Christoforou, Theopisti; Doumanidis, Charalabos

2010-09-01

267

Two-dimensional difference gel electrophoresis.  

PubMed

Two-dimensional difference gel electrophoresis (2D DIGE) is a modified form of 2D electrophoresis (2DE) that allows one to compare two or three protein samples simultaneously on the same gel. The proteins in each sample are covalently tagged with different color fluorescent dyes that are designed to have no effect on the relative migration of proteins during electrophoresis. Proteins that are common to the samples appear as "spots" with a fixed ratio of fluorescent signals, whereas proteins that differ between the samples have different fluorescence ratios. With the appropriate imaging system, difference gel electrophoresis (DIGE) is capable of reliably detecting as little as 0.2 fmol of protein, and protein differences down to ±15%, over a ?20,000-fold protein concentration range. DIGE combined with digital image analysis therefore greatly improves the statistical assessment of proteome variation. Here we describe a protocol for conducting DIGE experiments, which takes 2-3 days to complete. PMID:22585495

Minden, Jonathan S

2012-01-01

268

Novel absorption detection techniques for capillary electrophoresis.  

National Technical Information Service (NTIS)

Capillary electrophoresis (CE) has emerged as one of the most versatile separation methods. However, efficient separation is not sufficient unless coupled to adequate detection. The narrow inner diameter (I.D.) of the capillary column raises a big challen...

Y. Xue

1994-01-01

269

Capillary electrophoresis electrospray ionization mass spectrometry interface  

DOEpatents

The present invention is an interface between a capillary electrophoresis separation capillary end and an electrospray ionization mass spectrometry emitter capillary end, for transporting an anolyte sample from a capillary electrophoresis separation capillary to a electrospray ionization mass spectrometry emitter capillary. The interface of the present invention has: (a) a charge transfer fitting enclosing both of the capillary electrophoresis capillary end and the electrospray ionization mass spectrometry emitter capillary end; (b) a reservoir containing an electrolyte surrounding the charge transfer fitting; and (c) an electrode immersed into the electrolyte, the electrode closing a capillary electrophoresis circuit and providing charge transfer across the charge transfer fitting while avoiding substantial bulk fluid transfer across the charge transfer fitting. Advantages of the present invention have been demonstrated as effective in providing high sensitivity and efficient analyses.

Smith, Richard D. (Richland, WA); Severs, Joanne C. (Hayward, CA)

1999-01-01

270

High-performance capillary electrophoresis of histones  

SciTech Connect

A high performance capillary electrophoresis (HPCE) system has been developed for the fractionation of histones. This system involves electroinjection of the sample and electrophoresis in a 0.1M phosphate buffer at pH 2.5 in a 50 {mu}m {times} 35 cm coated capillary. Electrophoresis was accomplished in 9 minutes separating a whole histone preparation into its components in the following order of decreasing mobility; (MHP) H3, H1 (major variant), H1 (minor variant), (LHP) H3, (MHP) H2A (major variant), (LHP) H2A, H4, H2B, (MHP) H2A (minor variant) where MHP is the more hydrophobic component and LHP is the less hydrophobic component. This order of separation is very different from that found in acid-urea polyacrylamide gel electrophoresis and in reversed-phase HPLC and, thus, brings the histone biochemist a new dimension for the qualitative analysis of histone samples. 27 refs., 8 figs.

Gurley, L.R.; London, J.E.; Valdez, J.G.

1991-01-01

271

Preparative Sephadex Column Electrophoresis: An Improved Apparatus.  

National Technical Information Service (NTIS)

A preparative column electrophoresis using Sephadex G-25 as supporting medium offers a rapid and inexpensive method of purifying a large quantity of proteins with minimum sample loss. This apparatus has been very effective in separating closely related ho...

E. Kay J. H. C. Shih

1973-01-01

272

Analysis of Simple Carbohydrates by Capillary Electrophoresis and Capillary Electrophoresis–Mass Spectrometry  

Microsoft Academic Search

\\u000a An overview of the application of capillary electrophoresis and ­capillary electrophoresis–mass spectrometry in the analysis\\u000a of simple carbohydrates without any previous derivatization step is given. Besides electrolyte systems for ­carbohydrate separation,\\u000a detection techniques employed in capillary electrophoresis, such as ­spectrophotometric detection, electrochemical detection,\\u000a and mass spectrometric ­detection, are discussed, as are less common detection techniques. Thus, the chapter focuses on

Christian W. Klampfl; Markus Himmelsbach; Wolfgang Buchberger

273

Aptamers in Affinity Separations:Capillary Electrophoresis  

Microsoft Academic Search

Assays employing aptamers in capillary electrophoresis (CE), including competitive and noncompetitive assays, fluorescence polarization (FP) assays, nonequilibrium capillary electrophoresis of equilibrium mixtures, and affinity-polymerase chain reaction-CE assays, are summarized. These assays can be used to estimate dissociation rate and equilibrium binding constants, determine binding stoichiometries, study molecular interactions, and quantitatively determine specific analytes (e.g., proteins) in complex media. They can

Jeffrey W. Guthrie; Yuanhua Shao; X. Chris Le

2009-01-01

274

Electrophoresis of polymeric dyes in macroporous polymer  

Microsoft Academic Search

Summary  \\u000a Macroporous poly(styrene-co-divinylbenzene), with poly(vinyl alcohol) (PVA)-coated pores, was investigated as a novel medium\\u000a for thin-layer electrophoresis. The system was tested using polymeric dyes having polyelectrolyte character, which were prepared\\u000a by reaction of a vinylsulphone reactive dye (CI Reactive Blue 19) with PVA. Higher molar mass samples exhibited higher mobility\\u000a on electrophoresis in the macroporous medium.

Adrian D. Price; Peter M. Budd

2002-01-01

275

Lead Acetate, Teratology Study - Rabbits.  

National Technical Information Service (NTIS)

Three groups of 15 females rabbits were mated. Two groups were fed lead acetate in their diet at lead concentrations of 54.6 and 546 ppm from day 6 through day 16 of their gestation period. The third group of females and all males received the basal labor...

D. C. Jessup

1967-01-01

276

Analysis of illicit drugs by nonaqueous capillary electrophoresis and electrochemical detection.  

PubMed

Nonaqueous capillary electrophoresis (NACE) was applied to the determination of illicit drugs. The complete separation of amphetamine, methamphetamine, 3,4-methylene dioxy amphetamine (MDA), 3,4-methylene dioxy methamphetamine (MDMA), mescaline, cocaine and benzoylecgonine was obtained using an acetonitrile based buffer solution containing 10 mM sodium acetate and 1 M acetic acid. Electrochemical detection using a Pt microdisk electrode set to a potential of +1.8 V was found to be selective for MDA, MDMA and mescaline. The detection limits for these compounds were in the low ng/mL range which is between 2 and 3 orders of magnitude lower compared to UV-detection. PMID:11225861

Backofen, U; Matysik, F M; Hoffmann, W; Lunte, C E

2000-06-01

277

Vibrational spectroscopy and electrophoresis as a "golden means" in monitoring of polysaccharides in medical plant and gels.  

PubMed

In recent years, some bioactive polysaccharides isolated from natural sources have attracted much attention in the field of biochemistry and pharmacology. Of them, polysaccharides or their glycoconjugates were shown to exhibit multiple biological activities including anticarcinogenic, anticoagulant, immunostimulating, antioxidant, etc. Pharmacotherapy using plant-derived substances can be currently regarded as a very promising future alternative to conventional therapy. The advanced biotechnologies available today enable chemical investigation of well-defined bioactive plant components as sources of novel drugs. The need for safer drugs without side effects has led to the use of natural ingredients with proven safety. Special interest is focused on plant polysaccharides. This article attempts to review the current structural and conformational characterization of some importantly bioactive monosaccharides isolated from following plant cell-wall: Symphytum officinale (comfrey), Thymus pulegioides (thyme), Trigonella foenum-graecum L. (fenugreek), Tussilago farfara L. (coltsfoot), Hyssopus officinalis (hyssop), Althaea officinalis L. (marshmallow) and Equisetum arvense L. (horsetail). The chemical structures of monosaccharides were analysed using FTIR and Raman spectroscopies as well as cellulose acetate membrane electrophoresis (CAE). The dried plant samples were gently hydrolysed with sulphuric acid. The presence of glucuronic acid, galacturonic acid, alginic acid, glucose, mannose and xylose in the hydrolysates of reference substances and non-defatted plant films was proved. The possibility of a taxonomic classification of plant cell walls based on infrared and Raman spectroscopies and the use of spectral fingerprinting for authentication and detection of adulteration of products rich in cell-wall materials are discussed. Individual bands were selected to monitor the sugar content in medical plant cell walls and to confirm the identity of the analysed plants. PMID:22465769

Pielesz, A

2012-07-01

278

Vibrational spectroscopy and electrophoresis as a "golden means" in monitoring of polysaccharides in medical plant and gels  

NASA Astrophysics Data System (ADS)

In recent years, some bioactive polysaccharides isolated from natural sources have attracted much attention in the field of biochemistry and pharmacology. Of them, polysaccharides or their glycoconjugates were shown to exhibit multiple biological activities including anticarcinogenic, anticoagulant, immunostimulating, antioxidant, etc. Pharmacotherapy using plant-derived substances can be currently regarded as a very promising future alternative to conventional therapy. The advanced biotechnologies available today enable chemical investigation of well-defined bioactive plant components as sources of novel drugs. The need for safer drugs without side effects has led to the use of natural ingredients with proven safety. Special interest is focused on plant polysaccharides. This article attempts to review the current structural and conformational characterization of some importantly bioactive monosaccharides isolated from following plant cell-wall: Symphytum officinale (comfrey), Thymus pulegioides (thyme), Trigonella foenum-graecum L. (fenugreek), Tussilago farfara L. (coltsfoot), Hyssopus officinalis (hyssop), Althaea officinalis L. (marshmallow) and Equisetum arvense L. (horsetail). The chemical structures of monosaccharides were analysed using FTIR and Raman spectroscopies as well as cellulose acetate membrane electrophoresis (CAE). The dried plant samples were gently hydrolysed with sulphuric acid. The presence of glucuronic acid, galacturonic acid, alginic acid, glucose, mannose and xylose in the hydrolysates of reference substances and non-defatted plant films was proved. The possibility of a taxonomic classification of plant cell walls based on infrared and Raman spectroscopies and the use of spectral fingerprinting for authentication and detection of adulteration of products rich in cell-wall materials are discussed. Individual bands were selected to monitor the sugar content in medical plant cell walls and to confirm the identity of the analysed plants.

Pielesz, A.

279

BIOGENESIS OF CHLOROPLAST MEMBRANES  

PubMed Central

The development of photosynthetic lamellae during greening of dark-grown Chlamydomonas y-1 cells was investigated by radioautography. Acetate-3H was used as a marker for membrane lipids. In short pulse-labeling experiments, about 50–60% of the radioactivity incorporated was found in the lipid fraction and about 25–50% in starch granules present in the chloroplast of these algae. The relative specificity of acetate-3H used as a marker for membranes was artificially increased through quantitative removal of the starch granules from fixed cells by amylase treatment. Analysis of turnover coefficients of different membrane constituents and of the contribution of turnover and net synthesis to the total label incorporated in pulse experiments indicated that the incorporation of acetate into specific lipids was mainly due to net synthesis. The distribution of radioactivity in the different lipid constituents at the end of a short pulse and after 30- and 60-min chases indicated that transacylation is minimal and may be disregarded as a possible cause of randomization of the label. Statistical analysis of radioautographic grain distribution and measurements of different structural parameters indicate that (a) the chloroplast volume and surface remain constant during the process, whereas the growth of the photosynthetic lamellae parallels the increase in chlorophyll; (b) the lamellae do not develop from the chloroplast envelope or from the tubular system of the pyrenoid; (c) all the lamellae grow by incorporation of new material within preexisting structures; (d) different types of lamellae grow at different rates. The pyrenoid tubular system develops faster than the thylakoids, and single thylakoids develop about twice as fast as those which are paired or fused to grana. It is concluded that growth of the membranes occurs by a mechanism of random intussusception of molecular complexes within different types of preexisting membranes.

Goldberg, I.; Ohad, I.

1970-01-01

280

Application of denaturing gradient gel electrophoresis (DGGE) and temperature gradient gel electrophoresis (TGGE) in microbial ecology  

Microsoft Academic Search

Here, the state of the art of the application of denaturing gradient gel electrophoresis (DGGE) and temperature gradient gel electrophoresis (TGGE) in microbial ecology will be presented. Furthermore, the potentials and limitations of these techniques will be discussed, and it will be indicated why their use in ecological studies has become so important.

Gerard Muyzer; Kornelia Smalla

1998-01-01

281

Application of denaturing gradient gel electrophoresis (DGGE) and temperature gradient gel electrophoresis (TGGE) in microbial ecology  

Microsoft Academic Search

Here, the state of the art of the application of denaturing gradient gel electrophoresis (DGGE) and temperature gradient gel electrophoresis (TGGE) in microbial ecology will be presented. Furthermore, the potentials and limitations of these techniques will be discussed, and it will be indicated why their use in ecological studies has become so important. Abbreviations: ARDRA - amplified ribosomal DNA restriction

Gerard Muyzer; Kornelia Smalla

1998-01-01

282

Biofiltration of ethyl acetate and amyl acetate using a composite bead biofilter.  

PubMed

Biodegradation kinetic behaviors of ethyl acetate and amyl acetate in a composite bead biofilter were investigated. The composite bead was the spherical PVA/peat/KNO3/GAC composite bead which was prepared in our previous works. Both microbial growth rate and biochemical reaction rate were inhibited at higher inlet concentration. For the microbial growth process, the microbial growth rate of ethyl acetate was greater than that of amyl acetate in the inlet concentration range of 100-400ppm. The degree of inhibitive effect was almost the same for ethyl acetate and amyl acetate in this concentration range. The half-saturation constant Ks values of ethyl acetate and amyl acetate were 16.26 and 12.65ppm, respectively. The maximum reaction rate Vm values of ethyl acetate and amyl acetate were 4.08 and 3.53gCh(-1)kg(-1) packed material, respectively. Zero-order kinetic with the diffusion limitation could be regarded as the most adequate biochemical reaction model. For the biochemical reaction process, the biochemical reaction rate of ethyl acetate was greater than that of amyl acetate in the inlet concentration range of 100-400ppm. The inhibitive effect for ethyl acetate was more pronounced than that for AA in this concentration range. The maximum elimination capacity of ethyl acetate and amyl acetate were 82.3 and 37.93gCh(-1)m(-3) bed volume, respectively. Ethyl acetate degraded by microbial was easier than amyl acetate did. PMID:18445522

Chan, Wu-Chung; Su, Mei-Qi

2008-11-01

283

[Advances in functional genomics studies underlying acetic acid tolerance of Saccharomyces cerevisiae].  

PubMed

Industrial microorganisms are subject to various stress conditions, including products and substrates inhibitions. Therefore, improvement of stress tolerance is of great importance for industrial microbial production. Acetic acid is one of the major inhibitors in the cellulosic hydrolysates, which affects seriously on cell growth and metabolism of Saccharomyces cerevisiae. Studies on the molecular mechanisms underlying adaptive response and tolerance of acetic acid of S. cerevisiae benefit breeding of robust strains of industrial yeast for more efficient production. In recent years, more insights into the molecular mechanisms underlying acetic acid tolerance have been revealed through analysis of global gene expression and metabolomics analysis, as well as phenomics analysis by single gene deletion libraries. Novel genes related to response to acetic acid and improvement of acetic acid tolerance have been identified, and novel strains with improved acetic acid tolerance were constructed by modifying key genes. Metal ions including potassium and zinc play important roles in acetic acid tolerance in S. cerevisiae, and the effect of zinc was first discovered in our previous studies on flocculating yeast. Genes involved in cell wall remodeling, membrane transport, energy metabolism, amino acid biosynthesis and transport, as well as global transcription regulation were discussed. Exploration and modification of the molecular mechanisms of yeast acetic acid tolerance will be done further on levels such as post-translational modifications and synthetic biology and engineering; and the knowledge obtained will pave the way for breeding robust strains for more efficient bioconversion of cellulosic materials to produce biofuels and bio-based chemicals. PMID:25007573

Zhao, Xinqing; Zhang, Mingming; Xu, Guihong; Xu, Jianren; Bai, Fengwu

2014-03-01

284

Carbon-isotopic analysis of dissolved acetate  

NASA Technical Reports Server (NTRS)

Heating of dried, acetate-containing solids together with oxalic acid dihydrate conveniently releases acetic acid for purification by gas chromatography. For determination of the carbon-isotopic composition of total acetate, the acetate-containing zone of the chromatographic effluent can be routed directly to a combustion furnace coupled to a vacuum system allowing recovery, purification, and packaging of CO2 for mass-spectrometric analysis. For analysis of methyl carbon, acetic acid can be cryogenically trapped from the chromatographic effluent, then transferred to a tube containing excess NaOH. The tube is evacuated, sealed, and heated to 500 degrees C to produce methane by pyrolysis of sodium acetate. Subsequent combustion of the methane allows determination of the 13C content at the methyl position in the parent acetate. With typical blanks, the standard deviation of single analyses is less than 0.4% for acetate samples larger than 5 micromoles. A full treatment of uncertainties is outlined.

Gelwicks, J. T.; Hayes, J. M.

1990-01-01

285

Ozone decomposition in aqueous acetate solutions  

SciTech Connect

The acetate radical ion reacts with ozone with a rate constant of k = (1.5 +/- 0.5) x 10Z dmT mol s . The products from this reaction are CO2, HCHO, and O2 . By subsequent reaction of the peroxy radical with ozone the acetate radical ion is regenerated through the OH radical. A chain decomposition of ozone takes place. It terminates when the acetate radical ion reacts with oxygen forming the unreactive peroxy acetate radical. The chain is rather short as oxygen is developed, as a result of the ozone consumption. The inhibiting effect of acetate on the ozone decay is rationalized by OH scavenging by acetate and successive reaction of the acetate radical ion with oxygen. Some products from the bimolecular disappearance of the peroxy acetate radicals, however, react further with ozone, reducing the effectiveness of the stabilization.

Sehested, K.; Holcman, J.; Bjergbakke, E.; Hart, E.J.

1987-01-01

286

Combining electrophoresis with detection under ultraviolet light and multiple ultrafiltration for isolation of humic fluorescence fractions  

Microsoft Academic Search

Polyacrylamide gel electrophoresis of chernozem soil humic acids (HAs) followed by observation under UV (312nm) excitation light reveals new low molecular weight (MW) fluorescent fractions. Ultrafiltration of HAs sample in 7M urea on a membrane of low nominal MW retention (NMWR, 5kDa) was repetitively used for separation of fluorescent and non-fluorescent species. Thirty ultrafiltrates and the final retentate R were

Olga E. Trubetskaya; Lubov A. Shaloiko; Dmitrii V. Demin; Victor V. Marchenkov; Ivan I. Proskuryakov; Christian Coelho; Oleg A. Trubetskoj

2011-01-01

287

Carbon-isotopic analysis of dissolved acetate  

Microsoft Academic Search

Heating of dried, acetate-containing solids together with oxalic acid dihydrate conveniently releases acetic acid for purification by gas chromatography. For determination of the carbon-isotopic composition of total acetate, the acetate-containing zone of the chromatographic effluent can be routed directly to a combustion furnace coupled to a vacuum system allowing recovery, purification, and packaging of COâ for mass-spectrometric analysis. For analysis

Jeffrey T. Gelwicks; J. M. Hayes

1990-01-01

288

21 CFR 184.1185 - Calcium acetate.  

Code of Federal Regulations, 2011 CFR

, CAS Reg. No. 62-54-4), also known as acetate of lime or vinegar salts, is the calcium salt of acetic acid. It may be produced by the calcium hydroxide neutralization of acetic acid. (b) The ingredient meets the specifications of the Food Chemicals Codex, 3d Ed. (1981),...

2013-04-01

289

21 CFR 184.1185 - Calcium acetate.  

Code of Federal Regulations, 2010 CFR

, CAS Reg. No. 62-54-4), also known as acetate of lime or vinegar salts, is the calcium salt of acetic acid. It may be produced by the calcium hydroxide neutralization of acetic acid. (b) The ingredient meets the specifications of the Food Chemicals Codex, 3d Ed. (1981),...

2012-04-01

290

A new injection method for soil nutrient analysis in capillary electrophoresis  

NASA Astrophysics Data System (ADS)

We present a new method for the direct injection of liquid sample into a capillary electrophoresis (CE) device. Instead of a double-T injection mechanism, a single inlet provided with a membrane filter is used. From a reservoir on top of this inlet, the liquid directly enters the separation channel through the membrane. The driving force is a short electrical pulse. This avoids an additional sample channel, so that the chip needs only three microfluidic connects and no mechanical sample pumping is demanded. The high injection reproducibility and the comparatively simple setup open up the way for mobile application of soil analysis.

Smolka, M.; Puchberger-Enengl, D.; Bipoun, M.; Fercher, G.; Klasa, A.; Krutzler, C.; Keplinger, F.; Vellekoop, M. J.

2013-05-01

291

Acetate-dependent methylation of two corrinoid proteins in extracts of Methanosarcina barkeri.  

PubMed Central

Corrinoid proteins have been implicated as methyl carriers in methane formation from acetate, yet specific corrinoid proteins methylated by acetate-derived intermediates have not been identified. In the presence of ATP, H2, and bromoethanesulfonic acid, label from 3H- or 2-14C-labeled acetate was incorporated into the protein fraction of cell extracts of Methanosarcina barkeri. Incorporated label was susceptible to photolysis, yielding labeled methane as the anaerobic photolysis product. Size exclusion high-pressure liquid chromatography (HPLC) demonstrated the presence of at least three labeled proteins with native molecular sizes of 480, 200, and 29 kDa, while electrophoresis indicated that four major labeled proteins were present. Dual-label experiments demonstrated that these four proteins were methylated rather than acetylated. Two of the proteins (480 and 29 kDa) contained the majority of radiolabel and were stably methylated. After labeling with [2-14C]acetate, the stable 14CH3-proteins were partially purified, and 14CH3-cofactors were isolated from each protein. UV-visible spectroscopy and HPLC demonstrated these to be methylated corrinoids. When the 480-kDa corrinoid protein was purified to 70% homogeneity, the preparation was found to have subunits of 40 and 30 kDa. The 480-kDa protein but not the 29-kDa protein was methylated during in vitro methanogenesis from acetate and demethylated as methanogenesis ceased, consistent with the involvement of this protein in methane formation. Images

Cao, X J; Krzycki, J A

1991-01-01

292

Aptamers in Affinity Separations:Capillary Electrophoresis  

Microsoft Academic Search

\\u000a Assays employing aptamers in capillary electrophoresis (CE), including competitive and noncompetitive assays, fluorescence\\u000a polarization (FP) assays, nonequilibrium capillary electrophoresis of equilibrium mixtures, and affinity-polymerase chain\\u000a reaction-CE assays, are summarized. These assays can be used to estimate dissociation rate and equilibrium binding constants,\\u000a determine binding stoichiometries, study molecular interactions, and quantitatively determine specific analytes (e.g., proteins)\\u000a in complex media. They can

Jeffrey W. Guthrie; Yuanhua Shao; X. Chris Le

293

Identification of viroids by gel electrophoresis.  

PubMed

Two-dimensional PAGE involving an initial fractionation under nondenaturing conditions followed by a second electrophoresis under denaturing conditions provides a powerful means to detect viroids and other small circular RNAs. This unit describes a method known as "R(eturn) PAGE" in which denaturation is achieved by simultaneously raising the temperature and lowering the ionic strength during the second electrophoresis. Under denaturing conditions, circular RNAs migrate more slowly than their corresponding linear forms. Following fractionation, RNAs are visualized by staining with ethidium bromide, SYBR Gold, or silver nitrate. Unlike nucleic acid hybridization or RT-PCR, viroid identification by R-PAGE requires no nucleotide sequence information. PMID:18729055

Owens, Robert A

2008-08-01

294

Application of Microchip Electrophoresis for Clinical Tests  

NASA Astrophysics Data System (ADS)

Microchip electrophoresis has recently attracted much attention in the field of nuclear acid analysis due to its high efficiency, ease of operation, low consumption of samples and reagents, and relatively low costs. In addition, the analysis has expanded to an analytical field like not only the analysis of DNA but also the analysis of RNA, the protein, the sugar chain, and the cellular function, etc. In this report, we showed that high-performance monitoring systems for human blood glucose levels and ?-amylase activity in human plasma using microchip electrophoresis.

Yatsushiro, Shouki; Kataoka, Masatoshi

295

The interplay of phase inversion and membrane formation in the drug release characteristics of a membrane-based delivery system  

Microsoft Academic Search

The interplay of phase inversion and membrane formation in the drug release characteristics of a cellulose acetate (CA) membrane-based delivery system has been examined. Drug encapsulated films were cast from solutions of naproxen (drug), CA (polymer), acetone (solvent), and water (nonsolvent). Membrane morphologies, drug release kinetics, and drug–polymer interactions were studied using scanning electron microscopy (SEM), USP apparatus 5 dissolution

Decheng Ma; Anthony J. McHugh

2007-01-01

296

Membrane isolation on polylysine-coated beads. Plasma membrane from HeLa cells  

PubMed Central

HeLa cell plasma membranes have been purified after binding cells to polylysine-coated polyacrylamide beads. Cell attachment to beads and membrane recovery were maximal in a sucrose-acetate buffer, pH 5.0, at 25 degrees C. Measurements of ouabain-sensitive NaK-adenosine triphosphatase, membrane-bound 125I-wheat germ agglutinin, and chemical analyses showed that membranes on beads were of comparable or greater purity than membranes isolated by conventional methods. Because the isolation procedure is rapid (approximately 2.5 h), and produces membranes whose protoplasmic surfaces are fully exposed, it should be a useful supplement to standard isolation techniques.

1977-01-01

297

Cellulose membranes for reverse osmosis part II. Improving RO membranes prepared from non-woody cellulose  

Microsoft Academic Search

Experiments were carried out to minimize the stages of preparing reverse osmosis (RO) desalination membranes at economical cost and to improve the transport properties of RO membranes prepared from non-wood fibrous materials (cotton linters and bagasse pulp) to approach those prepared from imported viscose pulp and purchased cellulose acetate (see Part I). Further study was carried out on examining the

Altaf H. Basta; Houssni El-Saied; M. Elberry

2003-01-01

298

DNA ADDUCT RESEARCH WITH CAPILLARY ELECTROPHORESIS  

EPA Science Inventory

DNA's central importance in all biological systems dictates a wide variety of DNA-related research. or much of this research, the utilization of capillary electrophoresis (CE) can be of significant advantage. pen-tube CE yields excellent separations of DNA components, which can b...

299

Lanes Detection in PCR Gel Electrophoresis Images  

Microsoft Academic Search

This study aims at development of methods to track the center of and detect lanes as the first step of automated tooì to analyze rose DNA using PCR gel electrophoresis images. Although several research results have been previously reported using projection profiles in a whole image, it is still challenge to track the center of and detect bent lanes using

Sang Cheol Park; In Seop Na; Soo Hyung Kim; Guee Sang Lee; Kang Han Oh; Jeong Hwan Kim; Tae Ho Han

2011-01-01

300

Increasing Sensitivity In Continuous-Flow Electrophoresis  

NASA Technical Reports Server (NTRS)

Sensitivity of continuous-flow electrophoresis (CFE) chamber increased by introducing lateral gradients in concentration of buffer solution and thickness of chamber. Such gradients, with resulting enhanced separation, achieved in CFE chamber with wedge-shaped cross section and collateral flow. Enables improved separations of homogeneous components of mixtures of variety of biologically important substances.

Sharnez, Rizwan; Sammons, David W.

1994-01-01

301

The repton model of gel electrophoresis  

NASA Astrophysics Data System (ADS)

We discuss the repton model of agarose gel electrophoresis of DNA. We review previous results, both analytic and numerical, as well as presenting a new numerical algorithm for the efficient simulation of the model, and suggesting a new approach to the model's analytic solution.

Barkema, G. T.; Newman, M. E. J.

1997-02-01

302

The Genetic Science Learning Center: Gel Electrophoresis  

NSDL National Science Digital Library

Gel Electrophoresis, designed and run by the University of Utah, is an interactive program that allows the student to learn and practice basic techniques that molecular biologists use every day. This program is an interactive animated procedure that allows the user to "see" DNA strands and instructs the student or user on the basics of DNA.

2007-04-05

303

Low voltage electrophoresis on a CMOS chip  

Microsoft Academic Search

Electrophoresis is a valuable technique for the separation and analysis of chemical and biological specimens. Typically, an electric field is established between two electrodes that induces charged particles to move and separate. Instead of using only one electrode at each end of the separation area, this paper presents a very small, low voltage system that utilizes electrodes beneath the entire

Heather A. Wake; Martin A. Brooke

2007-01-01

304

Study on dicarboxylic acids in aerosol samples with capillary electrophoresis.  

PubMed

The research was performed to study the simultaneous detection of a homologous series of ? , ? -dicarboxylic acids (C2-C10), oxalic, malonic, succinic, glutaric, adipic, pimelic, suberic, azelaic, and sebacic acids, with capillary electrophoresis using indirect UV detection. Good separation efficiency in 2,6-pyridinedicarboxylic acid as background electrolyte modified with myristyl trimethyl ammonium bromide was obtained. The dicarboxylic acids were ionised and separated within five minutes. For the study, authentic samples were collected onto dry cellulose membrane filters of a cascade impactor (12 stages) from outdoor spring aerosols in an urban area. Hot water and ultrasonication extraction methods were used to isolate the acids from membrane filters. Due to the low concentrations of acids in the aerosols, the extracts were concentrated with solid-phase extraction (SPE) before determination. The enrichment of the carboxylic acids was between 86 and 134% with sample pretreatment followed by 100-time increase by preparation of the sample to 50? ? L. Inaccuracy was optimised for all the sample processing steps. The aerosols contained dicarboxylic acids C2-C10. Then, mostly they contained C2, C5, and C10. Only one sample contained succinic acid. In the study, the concentrations of the acids in aerosols were lower than 10?ng/m(3). PMID:24729915

Adler, Heidi; Sirén, Heli

2014-01-01

305

Study on Dicarboxylic Acids in Aerosol Samples with Capillary Electrophoresis  

PubMed Central

The research was performed to study the simultaneous detection of a homologous series of ?, ?-dicarboxylic acids (C2–C10), oxalic, malonic, succinic, glutaric, adipic, pimelic, suberic, azelaic, and sebacic acids, with capillary electrophoresis using indirect UV detection. Good separation efficiency in 2,6-pyridinedicarboxylic acid as background electrolyte modified with myristyl trimethyl ammonium bromide was obtained. The dicarboxylic acids were ionised and separated within five minutes. For the study, authentic samples were collected onto dry cellulose membrane filters of a cascade impactor (12 stages) from outdoor spring aerosols in an urban area. Hot water and ultrasonication extraction methods were used to isolate the acids from membrane filters. Due to the low concentrations of acids in the aerosols, the extracts were concentrated with solid-phase extraction (SPE) before determination. The enrichment of the carboxylic acids was between 86 and 134% with sample pretreatment followed by 100-time increase by preparation of the sample to 50??L. Inaccuracy was optimised for all the sample processing steps. The aerosols contained dicarboxylic acids C2–C10. Then, mostly they contained C2, C5, and C10. Only one sample contained succinic acid. In the study, the concentrations of the acids in aerosols were lower than 10?ng/m3.

Adler, Heidi; Siren, Heli

2014-01-01

306

Plasmodium falciparum Polypeptides Associated with the Infected Erythrocyte Plasma Membrane  

NASA Astrophysics Data System (ADS)

Plasmodium falciparum proteins associated with plasma membranes of infected erythrocytes were identified by using three techniques: (i) isolated plasma membranes from infected and uninfected erythrocytes were compared by gel electrophoresis and silver staining; (ii) isolated plasma membranes from cells metabolically labeled with [35S]methionine were assayed by gel electrophoresis; and (iii) uninfected and infected intact erythrocytes were surface-labeled by lactoperoxidase iodination, and the labeled polypeptides were compared by gel electrophoresis. The results from these experiments indicate that at least six parasite-derived polypeptides (Mr = > 240,000, 150,000, 55,000, 45,000, 35,000, and 20,000) are associated with the infected erythrocyte plasma membrane. At least four of these peptides (Mr = 55,000, 45,000, 35,000, and 20,000) may be exposed on the surface of the infected erythrocytes.

Stanley, Harold A.; Reese, Robert T.

1986-08-01

307

Plasma membrane of Entamoeba histolytica  

PubMed Central

Axenically propagated Entamoeba histolytica (HK9:NIH strain) were employed as starting material for the isoation of plasma membrane by a novel procedure. In the absence of known enzymatic markers, the externally disposed polypeptides of intact amoebae were iodinated and the incorporated label used to monitor membrane separation and recovery. 12 major plasma membrane polypeptides (12 x 10(3)-200 x 10(3) mol wt) were labeled and separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Each of these was a glycoprotein. Preincubation of amoebae with concanavalin A stabilized the plasma membranes as large sheets, facilitating its separation by low-speed centrifugation. Dissociation of the lectin with alpha-methyl mannoside, followed by additional homogenization led to vesiculation and further purification. The isolated plasma membrane was recovered in high yield (28%) and enriched 30-fold in terms of incorporated iodide. All iodinated surface glycoproteins of the intact organism were present in the plasma membrane fraction. A Ca++-dependent ATPase was enriched in the plasma membrane to a similar extent, but over one-half of the total activity was associated with internal, unlabeled membranes, suggesting a dual localization of this activity. The isolated plasma membrane was enriched in cholesterol and had a cholesterol:molar ratio of 0.87. It also contained larger amounts of an unusual phospholipid--ceramide aminoethyl phosphonate--a phospholipase-resistant species.

1980-01-01

308

Phorbol myristate acetate receptors in human polymorphonuclear neutrophils  

SciTech Connect

Resting or phorbol myristate acetate (PMA)-pretreated neutrophils were disrupted by nitrogen cavitation and were fractionated on Percoll density gradients to identify the subcellular location of PMA receptors. Receptors were found in the cytoplasm of resting cells; neither primary nor secondary granules bound (/sup 3/H)PMA, and the few binding sites located in non-granule membrane fractions appeared to reflect cytosolic contamination. Contrastingly, PMA-pretreated cells lost cytosolic receptors; > 80% of PMA-binding sites were associated with non-granule membranes. Protein kinase C activity similarly shifted from cytosol to membranes after PMA treatment. Indeed, protein kinase C and PMA receptors co-sedimented on Percoll gradients, co-eluted from Ultragel AcA 44 columns loaded with neutrophil cytoplasm, and were identically influenced by various phospholipids. Finally, PMA, mezerein, diacylglycerol, and dialkylglycerol activated protein kinase C with potencies that paralleled their respective abilities to stimulate neutrophil aggregation responses and inhibit (/sup 3/H)PMA binding to whole cells or cytosol. These results fit a model of stimulus-response coupling wherein exogenous PMA or endogenous diacylglycerol solvate in cellular membranes. Cytosolic protein kinase C binds to the intramembranous ligand, forming an active, membrane-associated complex that phosphorylates nearby elements involved in triggering aggregation and other responses.

Nishihira, J.; O'Flaherty, J.T.

1985-11-01

309

Development of nanofibrous cellulose acetate/gelatin skin substitutes for variety wound treatment applications.  

PubMed

The major component of fibrous extracellular matrix of dermis is composed of a complex combination of proteins and polysaccharides. Electrospun cellulose acetate/gelatin might be an effective simulator of the structure and composition of native skin and during this study, we electrospun cellulose acetate/gelatin membranes in various compositions and their performance as a scaffold for either skin tissue engineering or as a wound dressing was evaluated. Skin treatment products, whether tissue-engineered scaffolds or wound dressings, should be sufficiently hydrophilic to allow for gas and fluid exchange and absorb excess exudates while controlling the fluid loss. However, a wound dressing should be easily removable without causing tissue damage and a tissue-engineered scaffold should be able to adhere to the wound, and support cell proliferation during skin regeneration. We showed that these distinct adherency features are feasible just by changing the composition of cellulose acetate and gelatin in composite cellulose acetate/gelatin scaffolds. High proliferation of human dermal fibroblasts on electrospun cellulose acetate/gelatin 25:75 confirmed the capability of cellulose acetate/gelatin 25:75 nanofibers as a tissue-engineered scaffold, while the electrospun cellulose acetate/gelatin 75:25 can be a potential low-adherent wound dressing. PMID:23640859

Vatankhah, Elham; Prabhakaran, Molamma P; Jin, Guorui; Mobarakeh, Laleh Ghasemi; Ramakrishna, Seeram

2014-02-01

310

Comparative actions of progesterone, medroxyprogesterone acetate, drospirenone and nestorone on breast cancer cell migration and invasion  

Microsoft Academic Search

BACKGROUND: Limited information is available on the effects of progestins on breast cancer progression and metastasis. Cell migration and invasion are central for these processes, and require dynamic cytoskeletal and cell membrane rearrangements for cell motility to be enacted. METHODS: We investigated the effects of progesterone (P), medroxyprogesterone acetate (MPA), drospirenone (DRSP) and nestorone (NES) alone or with 17?-estradiol (E2)

Xiao-Dong Fu; Maria Silvia Giretti; Lorenzo Goglia; Marina Ines Flamini; Angel Matias Sanchez; Chiara Baldacci; Silvia Garibaldi; Regine Sitruk-Ware; Andrea Riccardo Genazzani; Tommaso Simoncini

2008-01-01

311

Using Gel Electrophoresis To Illustrate Protein Diversity and Isoelectric Point.  

ERIC Educational Resources Information Center

Demonstrates the differences in protein structures by focusing on isoelectric point with an experiment that is observable under certain pH levels in gel electrophoresis. Explains the electrophoresis procedure and reports results of the experiments. (YDS)

Browning, Mark; Vanable, Joseph

2002-01-01

312

Gel Electrophoresis on a Budget to Dye For  

NSDL National Science Digital Library

Gel electrophoresis is one of the most important tools used in molecular biology and has facilitated the entire field of genetic engineering by enabling the separation of nucleic acids and proteins. However, commercial electrophoresis kits can cost up to

Yu, Julie H.

2010-01-01

313

Lipoprotein Agarose Gel Electrophoresis. Application in HDL-Cholesterol Methodology.  

National Technical Information Service (NTIS)

We perform agarose gel lipoprotein electrophoresis (AGLE) in this laboratory using glass microscope slides to support the agarose gel and 0.025 M barbital buffer for the electrophoresis. This report describes details, including special apparatus used to f...

E. L. Mosser D. A. Clark

1985-01-01

314

Preparation of electrospun silk fibroin\\/Cellulose Acetate blend nanofibers and their applications to heavy metal ions adsorption  

Microsoft Academic Search

Silk fibroin (SF)\\/Cellulose Acetate (CA) blend nanofibrous membranes were prepared by electrospinning and their heavy metal\\u000a absorbabilities were examined in an aqueous solution after ethanol treatment. The electrospun nanofibrous membranes were comprised\\u000a of randomly oriented ultrafine fibers of 100–600 nm diameters. As a result of field emission electron microscope (FEEM), the\\u000a anti-felting properties of the blend nanofibrous membranes were markedly

Weitao Zhou; Jianxin He; Shizhong Cui; Weidong Gao

2011-01-01

315

Reconstitution in vitro of neurotoxin-responsive ion efflux by using membrane glycoproteins of neuroblastoma cells.  

PubMed Central

Glycoproteins were purified from a clonal cell line of mouse neuroblastoma, N-18, labeled metabolically with L-[3H]fucose. The purified radioactive glycoproteins were reconstituted into artificial phosphatidylcholine vesicles. When the vesicles were preloaded with cesium acetate and treated with neurotoxins to activate the Na+ channel, a shift in intravesicular density was observed to a less dense position after centrifugation on sucrose gradients. This shift was partially inhibited by tetrodotoxin, which prevents the activation of the Na+ channel. A similarly derived fraction of [14C]fucose-containing glycoproteins from a neuroblastoma cell line that does not possess excitable membranes, N1A-103, was reconstituted into phospholipid vesicles, and, after preloading with cesium ions, the fraction was combined with those of the 3H-labeled glycoproteins of the differentiated cells, N-18, which have excitable membranes. Only the 3H-labeled glycoprotein-containing vesicles were responsive to the neurotoxins, as shown by a shift in intravesicular density on sucrose gradients. These results are interpreted as a demonstration of the reconstitution of glycoproteins to form the activated Na+ channel. Comparison of the radioactive glycoprotein profiles after polyacrylamide gel electrophoresis showed that glycoproteins of Mr 200,000, Mr 165,000, and Mr 65,000 were common to the reconstituted fractions that were biologically active.

Giovanni, M Y; Glick, M C

1983-01-01

316

INTERVAL CARRIER FREE ELECTROPHORESIS FOR HIGH RESOLUTION PROTEIN PURIFICATION  

Microsoft Academic Search

Interval free flow zone electrophoresis is a new mode of free flow zone electrophoresis (FFZE), which facilitates purification of proteins and other molecular substances at very high resolution. It can be performed in the commercially available free flow electrophoresis (FFE) apparatus Octopus. The specimens are loaded and unloaded as usual with the help of a thin buffer film flowing between

Johann Bauer; Gerhard Weber

1998-01-01

317

Protein Electrophoresis in the Biology Classroom Using "Safe" Gels.  

ERIC Educational Resources Information Center

Describes the use of electrophoresis in the high school utilizing two new gels that are easy to pour, do not require degassing, can be used on a horizontal gel electrophoresis, and are not neurotoxic or carcinogenic health hazards. Large diagrams and written instructions are used to present the protocol of setting up the electrophoresis. (PR)

Atkins, Thomas

1991-01-01

318

Activation of bronchial mucin proteolysis by 4-aminophenylmercuric acetate and disulphide bond reducing agents.  

PubMed

High molecular weight bronchial glycoproteins, as nearly native as possible, were treated with either 2-mercaptoethanol or 4-aminophenylmercuric acetate (APMA): analytical electrophoresis revealed that a decrease in molecular weight of glycoproteins coincided with the disappearance of some proteins associated with high molecular weight bronchial glycoproteins. These modifications were not observed if high molecular weight bronchial glycoproteins were incubated with paramethylsulphonyl fluoride and EDTA, two synthetic protease-inhibitors, prior to 2-mercaptoethanol or APMA action. These data suggest that protease-antiprotease complexes are associated with bronchial mucins and that reducing agents or APMA activate proteases. PMID:6860710

Houdret, N; Lamblin, G; Scharfman, A; Humbert, P; Roussel, P

1983-07-01

319

Radical addition of methyldichlorosilane to vinyl acetate  

Microsoft Academic Search

The GC-MS method was used to identify the addition products of methyldichlorosilane to vinyl acetate. Radiation-induced addition of methyldichlorosilane to vinyl acetate produces 2-methyldichlorosilylethyl ethyl ether. The reaction follows a radical-chain mechanism. The ratio of the rate constants of methyldichlorosilyl radical addition to C=C and C=O to vinyl acetate amounts to 0.4±0.1 (303 K).

Yu. M. Lugovoi; N. P. Tarasova; G. Bourgeois; N. V. Bryantseva; V. V. Kostikov; C. Filliatre; A. G. Shostenko

1991-01-01

320

Graft polymerization of vinyl acetate onto silica  

Microsoft Academic Search

The free-radical graft polymerization of vi- nyl acetate onto nonporous silica particles was studied ex- perimentally. The grafting procedure consisted of surface activation with vinyltrimethoxysilane, followed by free-rad- ical graft polymerization of vinyl acetate in ethyl acetate with 2,2-azobis(2,4-dimethylpentanenitrile) initiator. Initial monomer concentration was varied from 10 to 40% by vol- ume and the reaction was spanned from 50 to

Van Nguyen; Wayne Yoshida; Yoram Cohen

2003-01-01

321

[Synthesis of ethriolophospholipids of acetal type].  

PubMed

New analogues of acetal-type phospholipids were obtained on the basis of ethriol (2-hydroxymethyl-2-ethyl-1,3-propanediol). The starting triol originally was condensed with decanal or dodecanal to form acetals, which were then phosphorylated with tetraethyldiamidophosphorous acid chloride. The amidophosphites were further oxidized with iodosobenzene or sulfurized to the corresponding acetal-type phospholipids and their thio analogues. PMID:17042275

Savin, G A

2006-01-01

322

Miscibility of cellulose acetate with vinyl polymers  

Microsoft Academic Search

Binary blend films of cellulose acetate (CA) with flexible syntheticpolymers including poly(vinyl acetate) (PVAc), poly(N-vinyl pyrrolidone) (PVP),and poly(N-vinyl pyrrolidone-co-vinyl acetate) [P(VP-co-VAc)] were preparedfrommixed polymer solutions by solvent evaporation. Thermal analysis by DSC showedthat CA of any degree of substitution (DS) was not miscible with PVAc, but CAwith DS less than 2.8 was miscible with PVP to form homogeneous blends. Thestate

Yoshiharu Miyashita; Tetsuya Suzuki; Yoshiyuki Nishio

2002-01-01

323

Oxidative reaction of oxindole-3-acetic acids.  

PubMed

The oxindole-3-acetic acids, oxidative metabolites of indole-3-acetic acid, were isolated from a byproduct of a corn starch manufacturing plant, and were further converted to the 3-hydroxyl derivatives in the presence of metal ion. The mechanical study was followed by a chemical analysis including other byproducts, and suggested the presence of an intermediate that had a radical at the C-3 position of oxindole-3-acetic acids. PMID:14519969

Niwa, Toshio; Ishii, Sayuri; Hiramatsu, Atsushi; Osawa, Toshihiko

2003-09-01

324

Comparison between agarose gel electrophoresis and capillary electrophoresis for variable numbers of tandem repeat typing of Mycobacterium tuberculosis  

Microsoft Academic Search

Variable numbers of tandem repeat (VNTR) typing of Mycobacterium tuberculosis was performed on 54 strains including 23 strains derived from 9 outbreaks. PCR amplicon sizes of 12 mycobacterial interspersed repetitive unit tandem repeat loci were measured using both agarose gel electrophoresis and capillary electrophoresis. Similarities using agarose gel electrophoresis of Euclidian distances among the 23 strains derived from the 9

Eiji Yokoyama; Kazunori Kishida; Masako Uchimura; Sadato Ichinohe

2006-01-01

325

Putative ABC Transporter Responsible for Acetic Acid Resistance in Acetobacter aceti  

PubMed Central

Two-dimensional gel electrophoretic analysis of the membrane fraction of Acetobacter aceti revealed the presence of several proteins that were produced in response to acetic acid. A 60-kDa protein, named AatA, which was mostly induced by acetic acid, was prepared; aatA was cloned on the basis of its NH2-terminal amino acid sequence. AatA, consisting of 591 amino acids and containing ATP-binding cassette (ABC) sequences and ABC signature sequences, belonged to the ABC transporter superfamily. The aatA mutation with an insertion of the neomycin resistance gene within the aatA coding region showed reduced resistance to acetic acid, formic acid, propionic acid, and lactic acid, whereas the aatA mutation exerted no effects on resistance to various drugs, growth at low pH (adjusted with HCl), assimilation of acetic acid, or resistance to citric acid. Introduction of plasmid pABC101 containing aatA under the control of the Escherichia coli lac promoter into the aatA mutant restored the defect in acetic acid resistance. In addition, pABC101 conferred acetic acid resistance on E. coli. These findings showed that AatA was a putative ABC transporter conferring acetic acid resistance on the host cell. Southern blot analysis and subsequent nucleotide sequencing predicted the presence of aatA orthologues in a variety of acetic acid bacteria belonging to the genera Acetobacter and Gluconacetobacter. The fermentation with A. aceti containing aatA on a multicopy plasmid resulted in an increase in the final yield of acetic acid.

Nakano, Shigeru; Fukaya, Masahiro; Horinouchi, Sueharu

2006-01-01

326

Aptamers in Affinity Separations:Capillary Electrophoresis  

NASA Astrophysics Data System (ADS)

Assays employing aptamers in capillary electrophoresis (CE), including competitive and noncompetitive assays, fluorescence polarization (FP) assays, nonequilibrium capillary electrophoresis of equilibrium mixtures, and affinity-polymerase chain reaction-CE assays, are summarized. These assays can be used to estimate dissociation rate and equilibrium binding constants, determine binding stoichiometries, study molecular interactions, and quantitatively determine specific analytes (e.g., proteins) in complex media. They can potentially be completed in under 60 s, detect zeptomol (10-24) amounts of analyte, be utilized in complex media with little or no cross reaction, and target a number of different analytes of biological, environmental, and clinical importance. This chapter briefly overviews the process of aptamer selection using CE and discusses the various CE-based bioanalytical methods that have been used to study biomolecular interactions.

Guthrie, Jeffrey W.; Shao, Yuanhua; Le, X. Chris

327

Capillary Electrophoresis Applied to Proteomic Analysis  

PubMed Central

In the postgenomic era, proteomics has become a dominant field for identifying and quantifying the complex protein machinery of the cell. The expression levels, post-translational modifications, and specific interactions of proteins control the biology of such processes as development, differentiation, and signal transduction. Studies of the proteins involved in these processes often leads to a better understanding of biology and of human disease. Powerful separation techniques and sensitive detection methods enable researchers to untangle these complicated networks of processes. Capillary electrophoresis coupled with either mass spectrometry or laser-induced fluorescence are two of the techniques that make this possible. This review will cover proven capillary electrophoresis-based methods for proteomics on the cell and tissue level and their application in biological and clinical studies, relevant new developments in enabling technology such as microfluidic CE-MS demonstrated on model systems, and comment on the future of CE in proteomics.

Fonslow, Bryan R.; Yates, John R.

2012-01-01

328

Sampling techniques for single-cell electrophoresis  

PubMed Central

Cells are extraordinarily complex, containing thousands of different analytes with concentrations spanning at least nine orders of magnitude. Analyzing single cells instead of tissue homogenates provides unique insights into cell-to-cell heterogeneity and aids in distinguishing normal cells from pathological ones. The high sensitivity and low sample consumption of capillary and on-chip electrophoresis, when integrated with fluorescence, electrochemical, and mass spectrometric detection methods, offer an ideal toolset for examining single cells and even subcellular organelles; however, the isolation and loading of such small samples into these devices is challenging. Recent advances have addressed this issue by interfacing a variety of enhanced mechanical, microfluidic, and optical sampling techniques to capillary and on-chip electrophoresis instruments for single-cell analyses.

Cecala, Christine; Sweedler, Jonathan V.

2013-01-01

329

A new approach to electrophoresis in space  

NASA Technical Reports Server (NTRS)

Previous electrophoresis experiments performed in space are reviewed. There is sufficient data available from the results of these experiments to show that they were designed with incomplete knowledge of the fluid dynamics of the process including electrohydrodynamics. Redesigning laboratory chambers and operating procedures developed on Earth for space without understanding both the advantages and disadvantages of the microgravity environment has yielded poor separations of both cells and proteins. However, electrophoreris is still an important separation tool in the laboratory and thermal convection does limit its performance. Thus, there is a justification for electrophoresis but the emphasis of future space experiments must be directed toward basic research with model experiments to understand the microgravity environment and fluid analysis to test the basic principles of the process.

Snyder, Robert S.; Rhodes, Percy H.

1990-01-01

330

Numerical simulation of electrophoresis separation processes  

NASA Technical Reports Server (NTRS)

A new Petrov-Galerkin finite element formulation has been proposed for transient convection-diffusion problems. Most Petrov-Galerkin formulations take into account the spatial discretization, and the weighting functions so developed give satisfactory solutions for steady state problems. Though these schemes can be used for transient problems, there is scope for improvement. The schemes proposed here, which consider temporal as well as spatial discretization, provide improved solutions. Electrophoresis, which involves the motion of charged entities under the influence of an applied electric field, is governed by equations similiar to those encountered in fluid flow problems, i.e., transient convection-diffusion equations. Test problems are solved in electrophoresis and fluid flow. The results obtained are satisfactory. It is also expected that these schemes, suitably adapted, will improve the numerical solutions of the compressible Euler and the Navier-Stokes equations.

Ganjoo, D. K.; Tezduyar, T. E.

1986-01-01

331

DNA electrophoresis in a nanofence array†  

PubMed Central

We present the design and implementation of an oxidized silicon “nanofence array” for long DNA electrophoresis. The device consists of a periodic array of post-filled regions (the nanofences) alternating with empty channel regions. Even in this prototype version, the nanofence array provides the resolving power of a hexagonal nanopost array without requiring any direct-write nanopatterning steps such as electron-beam lithography. Through detailed single molecule investigations, we demonstrate that the origin of the resolving power of the nanofence array is not a reduction in band broadening, which might be expected from the theories for DNA electrophoresis in post arrays. Rather, the enhanced stretching of the hooked DNA by the uniform electric field between nanofences increases the efficiency of the collisions.

Park, Sung-Gyu; Olson, Daniel W.

2012-01-01

332

Electrophoresis for genotyping: microtiter array diagonal gel electrophoresis on horizontal polyacrylamide gels, hydrolink, or agarose.  

PubMed

Electrophoresis of DNA has been performed traditionally in either an agarose or acrylamide gel matrix. Considerable effort has been directed to improved quality agaroses capable of high resolution, but for small fragments, such as those from polymerase chain reaction (PCR) and post-PCR digests, acrylamide still offers the highest resolution. Although agarose gels can easily be prepared in an open-faced format to gain the conveniences of horizontal electrophoresis, acrylamide does not polymerize in the presence of air and the usual configurations for gel preparation lead to electrophoresis in the vertical dimension. We describe here a very simple device and method to prepare and manipulate horizontal polyacrylamide gels (H-PAGE). In addition, the open-faced horizontal arrangement enables loading of arrays of wells. Since many procedures are undertaken in standard 96-well microtiter plates, we have also designed a device which preserves the exact configuration of the 8 x 12 array and enables electrophoresis in tracks following a 71.6 degrees diagonal between wells (MADGE, microtiter array diagonal gel electrophoresis), using either acrylamide or agarose. This eliminates almost all of the staff time taken in setup, loading, and recordkeeping and offers high resolution for genotyping pattern recognition. The nature and size of the gels allow direct stacking of gels in one tank, so that a tank used typically to analyze 30-60 samples can readily be used to analyze 1000-2000 samples. The gels would also enable robotic loading. Electrophoresis allows analysis of size and charge, parameters inaccessible to liquid-phase methods: thus, genotyping size patterns, variable length repeats, and haplotypes is possible, as well as adaptability to typing of point variations using protocols which create a difference detectable by electrophoresis. PMID:7864363

Day, I N; Humphries, S E

1994-11-01

333

Membrane stabilizer  

DOEpatents

A device is provided for stabilizing a flexible membrane secured within a frame, wherein a plurality of elongated arms are disposed radially from a central hub which penetrates the membrane, said arms imposing alternately against opposite sides of the membrane, thus warping and tensioning the membrane into a condition of improved stability. The membrane may be an opaque or translucent sheet or other material.

Mingenbach, William A. (P.O. Box 49, Taos, NM 87571)

1988-01-01

334

Creatininium 2-chloro-acetate  

PubMed Central

In the title compound (systematic name: 2-amino-1-methyl-4-oxo-4,5-dihydro-1H-imidazol-3-ium 2-chloro­acetate), C4H8N3O+·C2H2ClO2 ?, the mol­ecular aggregations are stabil­ized through classical (N—H?O) and non-classical (C—H?O and C—H?N) hydrogen-bonding inter­actions. The cations are linked to the anions, forming ion pairs through two N—H?O bonds that produce characteristic R 2 2(8) ring motifs. These cation–anion pairs are connected through another N—H?O hydrogen bond, leading to an R 4 2(8) ring motif. Further weak C—H?N inter­actions link the mol­ecules along the a axis, while other C—H?O inter­actions generate zigzag chains extending along b.

Ali, A. Jahubar; Athimoolam, S.; Bahadur, S. Asath

2012-01-01

335

Capillary zone electrophoresis-mass spectrometer interface  

DOEpatents

A device for providing equal electrical potential between two loci unconnected by solid or liquid electrical conductors is provided. The device comprises a first electrical conducting terminal, a second electrical conducting terminal connected to the first terminal by a rigid dielectric structure, and an electrically conducting gas contacting the first and second terminals. This device is particularly suitable for application in the electrospray ionization interface between a capillary zone electrophoresis apparatus and a mass spectrometer. 1 fig.

D`Silva, A.

1996-08-06

336

Velocity plateaus in traveling-wave electrophoresis.  

PubMed

One-dimensional models are used to study traveling-wave electrophoresis, a tunable method for separating charged analytes. A traveling-electrode model reveals the mechanism for longitudinal oscillations. A stationary-electrode model explains the origin of mode-locked plateaus in the average velocity, predicts devil's staircases with nested Farey sequences, and reduces to a continuum sinusoidal model in the high electrode-density limit. PMID:23214624

Correll, Robert; Edwards, Boyd F

2012-10-01

337

Capillary zone electrophoresis-mass spectrometer interface  

DOEpatents

A device for providing equal electrical potential between two loci unconnected by solid or liquid electrical conducts is provided. The device comprises a first electrical conducting terminal, a second electrical conducting terminal connected to the first terminal by a rigid dielectric structure, and an electrically conducting gas contacting the first and second terminals. This device is particularly suitable for application in the electrospray ionization interface between a capillary zone electrophoresis apparatus and a mass spectrometer.

D'Silva, Arthur (Ames, IA)

1996-08-06

338

Multiplexed fluorescence detector system for capillary electrophoresis  

DOEpatents

A fluorescence detection system for capillary electrophoresis is provided wherein the detection system can simultaneously excite fluorescence and substantially simultaneously monitor separations in multiple capillaries. This multiplexing approach involves laser irradiation of a sample in a plurality of capillaries through optical fibers that are coupled individually with the capillaries. The array is imaged orthogonally through a microscope onto a charge-coupled device camera for signal analysis. 14 figures.

Yeung, E.S.; Taylor, J.A.

1994-06-28

339

Portable electrophoresis apparatus using minimum electrolyte  

NASA Technical Reports Server (NTRS)

An electrophoresis unit for use in conducting electrophoretic analysis of specimens is described. The unit includes a sealable container in which a substrate mounted specimen is suspended in an electrolytic vapor. A heating unit is employed to heat a supply of electrolyte to produce the vapor. The substrate is suspended within the container by being attached between a pair of clips which also serve as electrodes to which a direct current power source may be connected.

Stevens, M. R.; Vickers, J. M. (inventors)

1976-01-01

340

Nonwoven fabric supported poly(acrylonitrile-vinyl acetate) gel electrolyte for lithium ion battery use  

Microsoft Academic Search

This paper reported on a new gel polymer electrolyte (GPE) based on polyethylene (PE) non-woven fabric supported poly(acrylonitrile-vinyl\\u000a acetate) (P(AN-VAc)\\/PE) membrane for lithium ion battery use. The preparation and performances of the P(AN-VAc)\\/PE membrane\\u000a and its GPE based on 1 M LiPF6 in dimethyl carbonate\\/diethylene carbonate\\/ethylene carbonate (1:1:1 in volume) were investigated with a comparison of the\\u000a unsupported P(AN-VAc) membrane. It

Xiaoping Li; Mumin Rao; Youhao Liao; Weishan Li; Mengqing Xu

2010-01-01

341

SOLID-PHASE ASSAY FOR THE PHOSPHORYLATION OF PROTEINS BLOTTED ON NITROCELLULOSE MEMBRANE FILTERS  

EPA Science Inventory

A new procedure for the phosphorylation and assay of phosphoproteins is described. Proteins are solubilized from tissue samples, separated by polyacrylamide gel electrophoresis, transferred onto nitrocellulose membrane filters and the blotted polypeptides are phosphorylated with ...

342

Capillary electrophoresis-based assessment of nanobody affinity and purity.  

PubMed

Drug purity and affinity are essential attributes during development and production of therapeutic proteins. In this work, capillary electrophoresis (CE) was used to determine both the affinity and composition of the biotechnologically produced "nanobody" EGa1, the binding fragment of a heavy-chain-only antibody. EGa1 is an antagonist of the epidermal growth factor receptor (EGFR), which is overexpressed on the surface of tumor cells. Using a background electrolyte (BGE) of 50mM sodium phosphate (pH 8.0) in combination with a polybrene-poly(vinylsulfonic acid) capillary coating, CE analysis of EGa1 showed the presence of at least three components. Affinity of the EGa1 components towards the extracellular domain of EGFR was assessed by adding different concentrations (0-12 nM) of the receptor to the BGE while measuring the effective electrophoretic mobility of the respective EGa1 components. Binding curves obtained by plotting electrophoretic mobility shifts as a function of receptor concentration, yielded dissociation constants (Kd) of 1.65, 1.67, and 1.75 nM for the three components, respectively; these values were comparable to the Kd of 2.1 nM obtained for the bulk EGa1 product using a cellular assay. CE with mass spectrometry (MS) detection using a BGE of 25 mM ammonium acetate (pH 8.0) revealed that the EGa1 sample comprised of significant amounts of deamidated, bisdeamidated and N-terminal pyroglutamic acid products. CE-MS using a BGE of 100mM acetic acid (pH 2.8) in combination with a polybrene-dextran sulfate-polybrene capillary coating demonstrated the additional presence of minor products related to incomplete removal of the signal peptide from the produced nanobody. Combining the results obtained from affinity CE and CE-MS, it is concluded that the EGa1 nanobody product is heterogeneous, comprising highly-related proteins that exhibit very similar affinity towards EGFR. PMID:24626396

Haselberg, Rob; Oliveira, Sabrina; van der Meel, Roy; Somsen, Govert W; de Jong, Gerhardus J

2014-03-25

343

Highly selective and efficient determination of US Environmental Protection Agency priority phenols employing solid-phase extraction and non-aqueous capillary electrophoresis  

Microsoft Academic Search

Non-aqueous capillary electrophoresis has been used in the separation of a complete list of 26 priority phenols included in the 8041 US Environmental Protection Agency method and the 76\\/464\\/EEC European Union directive. A highly selective and efficient separation was obtained when the background electrolyte used was 150 mM ammonium acetate dissolved in N-methylformamide–acetonitrile (75:25). Solid-phase extraction was successfully assayed as

S Morales; R Cela

2000-01-01

344

Automated extraction of direct, reactive, and vat dyes from cellulosic fibers for forensic analysis by capillary electrophoresis.  

PubMed

Systematic designed experiments were employed to find the optimum conditions for extraction of direct, reactive, and vat dyes from cotton fibers prior to forensic characterization. Automated microextractions were coupled with measurements of extraction efficiencies on a microplate reader UV-visible spectrophotometer to enable rapid screening of extraction efficiency as a function of solvent composition. Solvent extraction conditions were also developed to be compatible with subsequent forensic characterization of extracted dyes by capillary electrophoresis with UV-visible diode array detection. The capillary electrophoresis electrolyte successfully used in this work consists of 5 mM ammonium acetate in 40:60 acetonitrile-water at pH 9.3, with the addition of sodium dithionite reducing agent to facilitate analysis of vat dyes. The ultimate goal of these research efforts is enhanced discrimination of trace fiber evidence by analysis of extracted dyes. PMID:19536528

Dockery, C R; Stefan, A R; Nieuwland, A A; Roberson, S N; Baguley, B M; Hendrix, J E; Morgan, S L

2009-08-01

345

Electrophoretic extraction of proteins from two-dimensional electrophoresis gel spots  

DOEpatents

After two-dimensional electrophoresis of proteins or the like, resulting in a polyacrylamide gel slab having a pattern of protein gel spots thereon, an individual protein gel spot is cored out from the slab, to form a gel spot core which is placed in an extraction tube, with a dialysis membrane across the lower end of the tube. Replicate gel spots can be cored out from replicate gel slabs and placed in the extraction tube. Molten agarose gel is poured into the extraction tube where the agarose gel hardens to form an immobilizing gel, covering the gel spot cores. The upper end portion of the extraction tube is filled with a volume of buffer solution, and the upper end is closed by another dialysis membrane. Upper and lower bodies of a buffer solution are brought into contact with the upper and lower membranes and are provided with electrodes connected to the positive and negative terminals of a DC power supply, thereby producing an electrical current which flows through the upper membrane, the volume of buffer solution, the agarose, the gel spot cores and the lower membrane. The current causes the proteins to be extracted electrophoretically from the gel spot cores, so that the extracted proteins accumulate and are contained in the space between the agarose gel and the upper membrane. A high percentage extraction of proteins is achieved. The extracted proteins can be removed and subjected to partial digestion by trypsin or the like, followed by two-dimensional electrophoresis, resulting in a gel slab having a pattern of peptide gel spots which can be cored out and subjected to electrophoretic extraction to extract individual peptides.

Zhang, Jian-Shi (Shanghai, CN); Giometti, Carol S. (Glenview, IL); Tollaksen, Sandra L. (Montgomery, IL)

1989-01-01

346

(Acetoxy)(2-methylphenyl)methyl acetate  

PubMed Central

In the title compound, C12H14O4, the two acet­oxy groups are inclined by 57.92?(5)° and 62.71?(6)° to the benzene ring. An inter­molecular C—H?O inter­action involving the two acet­oxy groups generates a centrosymmetric dimer via an R 2 2(16) ring motif.

Kanchanadevi, J.; Anbalagan, G.; Saravanan, V.; Mohanakrishnan, A. K.; Manivannan, V.

2011-01-01

347

Biodegradable Plastics Based on Cellulose Acetate  

Microsoft Academic Search

It is generally known that secondary cellulose acetate (with 53 to 56% acetyl groups) is suitable for thermoplastic processing. With appropriate plasticizers a plastic material is obtained which excels in transparency and pleasant texture, and it is therefore often used for tool handles, combs, spectacle frames, and the like. In principle, cellulose acetate with such a degree of substitution is

Alexander Ach

1993-01-01

348

Carbon-isotopic analysis of dissolved acetate  

SciTech Connect

Heating of dried, acetate-containing solids together with oxalic acid dihydrate conveniently releases acetic acid for purification by gas chromatography. For determination of the carbon-isotopic composition of total acetate, the acetate-containing zone of the chromatographic effluent can be routed directly to a combustion furnace coupled to a vacuum system allowing recovery, purification, and packaging of CO{sub 2} for mass-spectrometric analysis. For analysis of methyl carbon, acetic acid can be cryogenically trapped from the chromatographic effluent, then transferred to a tube containing excess NaOH. The tube is evacuated, sealed, and heated to 500{degree}C to produce methane by pyrolysis of sodium acetate. Subsequent combustion of the methane allows determination of the {sup 13}C content at the methyl position in the parent acetate. With typical blanks, the standard deviation of single analyses is less than 0.4{per thousand} for acetate samples larger than 5 {mu}mol. A full treatment of uncertainties is outlined.

Gelwicks, J.T. (Merck and Co., Inc., Rahway, NJ (USA)); Hayes, J.M. (Indiana Univ., Bloomington (USA))

1990-03-01

349

The permeation performance of SBA15\\/CAP\\/PVDF blend membranes  

Microsoft Academic Search

To improve the mechanical strength of cellulose acetate (CA) membranes, porous inorganic\\/organic hybrid membranes were prepared via phase inversion technique from casting solution composed of cellulose acetate propionate (CAP), poly(vinylidene fluoride) (PVDF), mesoporous SBA-15 materials, and N-methyl-2-pyrrolidone (NMP). The effects of PVDF content and modification with SBA-15 on membranes structure, and properties were characterized in terms of fieldemission scanning electron

Yun-Chieh Su; Kuo-Liang Chuang; Ming-Chi Hsieh; Hui-Hsin Tseng; Li-Luen Huang

2010-01-01

350

Capillary Zone Electrophoresis-Electrospray Ionization-Tandem Mass Spectrometry for Top-Down Characterization of the Mycobacterium marinum Secretome.  

PubMed

Capillary zone electrophoresis (CZE) with an electrokinetically pumped sheath-flow nanospray interface was coupled with a high-resolution Q-Exactive mass spectrometer for the analysis of culture filtrates from Mycobacterium marinum. We confidently identified 22 gene products from the wildtype M. marinum secretome in a single CZE-tandem mass spectrometry (MS/MS) run. A total of 58 proteoforms were observed with post-translational modifications including signal peptide removal, N-terminal methionine excision, and acetylation. The conductivities of aqueous acetic acid and formic acid solutions were measured from 0.1% to 100% concentration (v/v). Acetic acid (70%) provided lower conductivity than 0.25% formic acid and was evaluated as low ionic-strength and a CZE-MS compatible sample buffer with good protein solubility. PMID:24725189

Zhao, Yimeng; Sun, Liangliang; Champion, Matthew M; Knierman, Michael D; Dovichi, Norman J

2014-05-20

351

Ulipristal acetate in emergency contraception.  

PubMed

Despite the widespread availability of highly effective methods of contraception, unintended pregnancy is common. Unplanned pregnancies have been linked to a range of health, social and economic consequences. Emergency contraception reduces risk of pregnancy after unprotected intercourse, and represents an opportunity to decrease number of unplanned pregnancies and abortions. Emergency contraception pills (ECP) prevent pregnancy by delaying or inhibiting ovulation, without interfering with post fertilization events. If pregnancy has already occurred, ECPs will not be effective, therefore ECPs are not abortificants. Ulipristal acetate (17alpha-acetoxy-11beta-(4N-N,N-dymethilaminophenyl)-19-norpregna--4,9-diene-3,20-dione) is the first drug that was specifically developed and licensed for use as an emergency contraceptive. It is an orally active, synthetic, selective progesterone modulator that acts by binding with high affinity to the human progesterone receptor where it has both antagonist and partial agonist effects. It is a new molecular entity and the first compound in a new pharmacological class defined by the pristal stem. Up on the superior clinical efficacy evidence, UPA has been quickly recognized as the most effective emergency contraceptive pill, and recently recommended as the first prescription choice for all women regardless of the age and timing after intercourse. This article provides literature review of UPA and its role in emergency contraception. PMID:24851646

Goldstajn, Marina Sprem; Baldani, Dinka Pavici?; Skrgati?, Lana; Radakovi?, Branko; Vrbi?, Hrvoje; Cani?, Tomislav

2014-03-01

352

Condensation nucleation light scattering detection for capillary electrophoresis.  

PubMed

We describe two means for interfacing condensation nucleation light scattering detection to capillary electrophoresis (CE). With the first method, a fused-silica capillary was used for the separation and the CE was grounded through a Nafion membrane that also connected the system to a microconcentric pneumatic nebulizer. Limits of detection (LODs) for underivatized amino acids were at the low microgram per milliliter level, and separation efficiencies were ?9 times lower than the optimum predicted for these species based on the injection plug width and axial dispersion by diffusion. LODs were limited by background nonvolatiles resulting from dissolution of fused silica at the high pHs used for the separations. An alternate system employed PEEK capillaries which acted as the separation capillary and also as the inner nebulizer capillary. In this case, the exit end of the capillary was coated with conductive paint which extended to the tip of the nebulizer, was in contact with the CE buffer, and was grounded to complete the CE circuit. Response was nonlinear and the separation efficiency of this system was somewhat lower than that for the Nafion membrane system. Response as peak heights for all of the amino acids and peptides studied was nearly identical on a mass basis. With this system, much lower background signals were obtained, and as a result, LODs for underivatized amino acids and peptides were below the 1 ?g/mL level, corresponding to less than 10 pg or less than 100 fmol injected. Both systems were fairly simple, effective means to generate aerosols with the low flows of CE and should be applicable to interfacing of other aerosol-based detectors with CE. PMID:21619346

Szostek, B; Koropchak, J A

1996-09-01

353

Electrophoretic extraction of proteins from two-dimensional electrophoresis gel spots  

DOEpatents

After two-dimensional electrophoresis of proteins or the like, resulting in a polyacrylamide gel slab having a pattern of protein gel spots thereon, an individual protein gel spot is cored out from the slab, to form a gel spot core which is placed in an extraction tube, with a dialysis membrane across the lower end of the tube. Replicate gel spots can be cored out from replicate gel slabs and placed in the extraction tube. Molten agarose gel is poured into the extraction tube where the agarose gel hardens to form an immobilizing gel, covering the gel spot cores. The upper end portion of the extraction tube is filled with a volume of buffer solution, and the upper end is closed by another dialysis membrane. Upper and lower bodies of a buffer solution are brought into contact with the upper and lower membranes and are provided with electrodes connected to the positive and negative terminals of a dc power supply, thereby producing an electrical current which flows through the upper membrane, the volume of buffer solution, the agarose, the gel spot cores and the lower membrane. The current causes the proteins to be extracted electrophoretically from the gel spot cores, so that the extracted proteins accumulate and are contained in the space between the agarose gel and the upper membrane. 8 figs.

Zhang, Jian-Shi; Giometti, C.S.; Tollaksen, S.L.

1987-09-04

354

The fluid mechanics of continuous flow electrophoresis  

NASA Astrophysics Data System (ADS)

The overall objective is to establish theoretically and confirm experimentally the ultimate capabilities of continuous flow electrophoresis chambers operating in an environment essentially free of particle sedimentation and buoyancy. The efforts are devoted to: (1) studying the effects of particle concentration on sample conductivity and dielectric constant. The dielectric constant and conductivity were identified as playing crucial roles in the behavior of the sample and on the resolving power and throughput of continuous flow devices; and (2) improving the extant mathematical models to predict flow fields and particle trajectories in continuous flow electrophoresis. A dielectric spectrometer was designed and built to measure the complex dielectric constant of a colloidal dispersion as a function of frequency between 500 Hz and 200 kHz. The real part of the signal can be related to the sample's conductivity and the imaginary part to its dielectric constant. Measurements of the dielectric constants of several different dispersions disclosed that the dielectric constants of dilute systems of the sort encountered in particle electrophoresis are much larger than would be expected based on the extant theory. Experiments were carried out to show that, in many cases, this behavior is due to the presence of a filamentary structure of small hairs on the particle surface. A technique for producing electrokinetically ideal synthetic latex particles by heat treating was developed. Given the ubiquitous nature of hairy surfaces with both cells and synthetic particles, it was deemed necessary to develop a theory to explain their behavior. A theory for electrophoretic mobility of hairy particles was developed. Finally, the extant computer programs for predicting the structure of electro-osmotically driven flows were extended to encompass flow channels with variable wall mobilities.

Saville, D. A.

1990-11-01

355

The fluid mechanics of continuous flow electrophoresis  

NASA Technical Reports Server (NTRS)

The overall objective is to establish theoretically and confirm experimentally the ultimate capabilities of continuous flow electrophoresis chambers operating in an environment essentially free of particle sedimentation and buoyancy. The efforts are devoted to: (1) studying the effects of particle concentration on sample conductivity and dielectric constant. The dielectric constant and conductivity were identified as playing crucial roles in the behavior of the sample and on the resolving power and throughput of continuous flow devices; and (2) improving the extant mathematical models to predict flow fields and particle trajectories in continuous flow electrophoresis. A dielectric spectrometer was designed and built to measure the complex dielectric constant of a colloidal dispersion as a function of frequency between 500 Hz and 200 kHz. The real part of the signal can be related to the sample's conductivity and the imaginary part to its dielectric constant. Measurements of the dielectric constants of several different dispersions disclosed that the dielectric constants of dilute systems of the sort encountered in particle electrophoresis are much larger than would be expected based on the extant theory. Experiments were carried out to show that, in many cases, this behavior is due to the presence of a filamentary structure of small hairs on the particle surface. A technique for producing electrokinetically ideal synthetic latex particles by heat treating was developed. Given the ubiquitous nature of hairy surfaces with both cells and synthetic particles, it was deemed necessary to develop a theory to explain their behavior. A theory for electrophoretic mobility of hairy particles was developed. Finally, the extant computer programs for predicting the structure of electro-osmotically driven flows were extended to encompass flow channels with variable wall mobilities.

Saville, D. A.

1990-01-01

356

Lipidomic profiling of Saccharomyces cerevisiae and Zygosaccharomyces bailii reveals critical changes in lipid composition in response to acetic acid stress.  

PubMed

When using microorganisms as cell factories in the production of bio-based fuels or chemicals from lignocellulosic hydrolysate, inhibitory concentrations of acetic acid, released from the biomass, reduce the production rate. The undissociated form of acetic acid enters the cell by passive diffusion across the lipid bilayer, mediating toxic effects inside the cell. In order to elucidate a possible link between lipid composition and acetic acid stress, the present study presents detailed lipidomic profiling of the major lipid species found in the plasma membrane, including glycerophospholipids, sphingolipids and sterols, in Saccharomyces cerevisiae (CEN.PK 113_7D) and Zygosaccharomyces bailii (CBS7555) cultured with acetic acid. Detailed physiological characterization of the response of the two yeasts to acetic acid has also been performed in aerobic batch cultivations using bioreactors. Physiological characterization revealed, as expected, that Z. bailii is more tolerant to acetic acid than S. cerevisiae. Z. bailii grew at acetic acid concentrations above 24 g L(-1), while limited growth of S. cerevisiae was observed after 11 h when cultured with only 12 g L(-1) acetic acid. Detailed lipidomic profiling using electrospray ionization, multiple-reaction-monitoring mass spectrometry (ESI-MRM-MS) showed remarkable changes in the glycerophospholipid composition of Z. bailii, including an increase in saturated glycerophospholipids and considerable increases in complex sphingolipids in both S. cerevisiae (IPC 6.2×, MIPC 9.1×, M(IP)2C 2.2×) and Z. bailii (IPC 4.9×, MIPC 2.7×, M(IP)2C 2.7×), when cultured with acetic acid. In addition, the basal level of complex sphingolipids was significantly higher in Z. bailii than in S. cerevisiae, further emphasizing the proposed link between lipid saturation, high sphingolipid levels and acetic acid tolerance. The results also suggest that acetic acid tolerance is associated with the ability of a given strain to generate large rearrangements in its lipid profile. PMID:24023914

Lindberg, Lina; Santos, Aline Xs; Riezman, Howard; Olsson, Lisbeth; Bettiga, Maurizio

2013-01-01

357

Microfluidic concentration of bacteria by on-chip electrophoresis  

PubMed Central

In this contribution, we present a system for efficient preconcentration of pathogens without affecting their viability. Development of miniaturized molecular diagnostic kits requires concentration of the sample, molecule extraction, amplification, and detection. In consequence of low analyte concentrations in real-world samples, preconcentration is a critical step within this workflow. Bacteria and viruses exhibit a negative surface charge and thus can be electrophoretically captured from a continuous flow. The concept of phaseguides was applied to define gel membranes, which enable effective and reversible collection of the target species. E. coli of the strains XL1-blue and K12 were used to evaluate the performance of the device. By suppression of the electroosmotic flow both strains were captured with efficiencies of up to 99%. At a continuous flow of 15??l/min concentration factors of 50.17?±?2.23 and 47.36?±?1.72 were achieved in less than 27?min for XL1-blue and K12, respectively. These results indicate that free flow electrophoresis enables efficient concentration of bacteria and the presented device can contribute to rapid analyses of swab-derived samples.

Puchberger-Enengl, Dietmar; Podszun, Susann; Heinz, Helene; Hermann, Carsten; Vulto, Paul; Urban, Gerald A.

2011-01-01

358

Capillary electrophoresis of anthraquinones from Cassia siamea.  

PubMed

The separation and determination of two anthraquinones, emodin and chrysophanol, and two bianthraquinones, cassiamin A and cassiamin B, were achieved by capillary electrophoresis (CE). The running electrolyte used in this method was 0.05 M hydroxypropyl-gamma-cyclodextrin in 0.1 M borate buffer (pH 9) containing 10% acetonitrile, with an applied voltage of 20 kV. Application of this technique in the determination of the main bianthraquinones, cassiamin A and cassiamin B, of Cassia siamea is demonstrated in this paper. PMID:12192145

Koyama, Junko; Morita, Izumi; Tagahara, Kiyoshi; Bakari, Jameelah; Aqil, Mohammad

2002-08-01

359

Hybrid slab-microchannel gel electrophoresis system  

DOEpatents

A hybrid slab-microchannel gel electrophoresis system. The hybrid system permits the fabrication of isolated microchannels for biomolecule separations without imposing the constraint of a totally sealed system. The hybrid system is reusable and ultimately much simpler and less costly to manufacture than a closed channel plate system. The hybrid system incorporates a microslab portion of the separation medium above the microchannels, thus at least substantially reducing the possibility of non-uniform field distribution and breakdown due to uncontrollable leakage. A microslab of the sieving matrix is built into the system by using plastic spacer materials and is used to uniformly couple the top plate with the bottom microchannel plate.

Balch, Joseph W. (Livermore, CA); Carrano, Anthony V. (Livermore, CA); Davidson, James C. (Livermore, CA); Koo, Jackson C. (San Ramon, CA)

1998-01-01

360

Biotechnology Laboratory: Gel Electrophoresis of Dyes  

NSDL National Science Digital Library

A portion of the Partnership for Plant Genomics Education, hosted by the University of California-Davis, this PDF presents a student activity where students will use agarose gel electrophoresis to separate several different dyes. The lab is described as a âÂÂprecursor to DNA separationsâ and thus provides an important step in the subject matter. The lab provides for students: detailed instructions, background information, and a quiz and group questions. Answers to the questions, and also the general objective of the lab, are provided for the instructor. Overall, the lab is introductory in nature and perfect for any science classroom.

2008-12-05

361

Fluid mechanics of continuous flow electrophoresis  

NASA Technical Reports Server (NTRS)

The following aspects of continuous flow electrophoresis were studied: (1) flow and temperature fields; (2) hydrodynamic stability; (3) separation efficiency, and (4) characteristics of wide gap chambers (the SPAR apparatus). Simplified mathematical models were developed so as to furnish a basis for understanding the phenomena and comparison of different chambers and operating conditions. Studies of the hydrodynamic stability disclosed that a wide gap chamber may be particularly sensitive to axial temperature variations which could be due to uneven heating or cooling. The mathematical model of the separation process includes effects due to the axial velocity, electro-osmotic cross flow and electrophoretic migration, all including the effects of temperature dependent properties.

Saville, D. A.; Ostrach, S.

1978-01-01

362

Doped with Sodium Acetate and Metallic Sodium  

NASA Astrophysics Data System (ADS)

We have investigated the thermoelectric properties of p-type Na-doped Mg2 Si0.25Sn0.75 solid solutions prepared by liquid-solid reaction and hot-pressing methods. Na was introduced into Mg2Si0.25Sn0.75 by using either sodium acetate (CH3COONa) or metallic sodium (2 N). The samples doped with sodium acetate consisted of phases with antifluorite structure and a small amount of MgO as revealed by x-ray diffraction, whereas the sample doped with metallic sodium contained the Sn, MgO, and Mg2SiSn phases. The hole concentrations of Mg1.975Na0.025Si0.25Sn0.75 doped by sodium acetate and metallic sodium were 1.84 × 1025 m-3 and 1.22 × 1025 m-3, respectively, resulting in resistivities of 4.96 × 10-5 ? m (sodium acetate) and 1.09 × 10-5 ? m (metallic sodium). The Seebeck coefficients were 198 ?V K-1 (sodium acetate) and 241 ?V K-1 (metallic sodium). The figures of merit for Mg1.975Na0.025Si0.25Sn0.75 were 0.40 × 10-3 K-1 (sodium acetate) and 0.25 × 10-3 K-1 (metallic sodium) at 400 K. Thus, sodium acetate is a suitable Na dopant for Mg2Si1- x Sn x .

Tada, Satoki; Isoda, Yukihiro; Udono, Haruhiko; Fujiu, Hirofumi; Kumagai, Shunji; Shinohara, Yoshikazu

2014-06-01

363

Biogenesis of plasma membrane cholesterol  

SciTech Connect

A striking feature of the molecular organization of eukaryotic cells is the singular enrichment of their plasma membranes in sterols. The authors studies are directed at elucidating the mechanisms underlying this inhomogeneous disposition. Cholesterol oxidase catalyzes the oxidation of plasma membrane cholesterol in intact cells, leaving intracellular cholesterol pools untouched. With this technique, the plasma membrane was shown to contain 95% of the unesterified cholesterol of cultured human fibroblasts. Cholesterol synthesized from (/sup 3/H) acetate moved to the plasma membrane with a half-time of 1 h at 37/sup 0/C. They used equilibrium gradient centrifugation of homogenates of biosynthetically labeled, cholesterol oxidase treated cells to examine the distribution of newly synthesized sterols among intracellular pools. Surprisingly, lanosterol, a major precursor of cholesterol, and intracellular cholesterol both peaked at much lower buoyant density than did 3-hydroxy-3-methylglutaryl-CoA reductase. This suggests that cholesterol biosynthesis is not taken to completion in the endoplasmic reticulum. The cholesterol in the buoyant fraction eventually moved to the plasma membrane. Digitonin treatment increased the density of the newly synthesized cholesterol fractions, indicating that nascent cholesterol in transit is associated with cholesterol-rich membranes. The authors are testing the hypothesis that the pathway of cholesterol biosynthesis is spatially organized in various intracellular membranes such that the sequence of biosynthetic steps both concentrates the sterol and conveys it to the plasma membrane.

Lange, Y.

1986-05-01

364

36 CFR 1232.24 - Unstable cellulose-acetate film.  

Code of Federal Regulations, 2010 CFR

...2009-07-01 2009-07-01 false Unstable cellulose-acetate film. 1232.24 Section 1232...Audiovisual Records Management § 1232.24 Unstable cellulose-acetate film. Cellulose-acetate film, also known as safety...

2009-07-01

365

21 CFR 172.833 - Sucrose acetate isobutyrate (SAIB).  

Code of Federal Regulations, 2010 CFR

... 2009-04-01 2009-04-01 false Sucrose acetate isobutyrate (SAIB). 172.833...CONSUMPTION Multipurpose Additives § 172.833 Sucrose acetate isobutyrate (SAIB). Sucrose acetate isobutyrate may be safely used in...

2009-04-01

366

21 CFR 172.833 - Sucrose acetate isobutyrate (SAIB).  

Code of Federal Regulations, 2010 CFR

...3 2010-01-01 2009-04-01 true Sucrose acetate isobutyrate (SAIB). 172.833...CONSUMPTION Multipurpose Additives § 172.833 Sucrose acetate isobutyrate (SAIB). Sucrose acetate isobutyrate may be safely used in...

2010-01-01

367

Determination of creatine and phosphocreatine in muscle biopsy samples by capillary electrophoresis with contactless conductivity detection.  

PubMed

A capillary electrophoresis method with contactless conductivity detection was evaluated as a new approach for quantification of creatine and phosphocreatine in human quadriceps femoris biopsy samples. The running buffers employed consisted of 1 M acetic acid at a pH of 2.3 for the determination of creatine and 50 mM 3-(N-morpholino)propanesulfonic acid/30 mM histidine at a pH of 6.4 for the determination of phosphocreatine in the centrifuged muscle extracts. The limits of detection for creatine and phosphocreatine were found to be 2.5 and 1.0 ?M, respectively. Creatine and phosphocreatine were determined in six human muscle biopsy samples and the results were found comparable to those of a standard enzymatic assay. The procedures developed for creatine and phosphocreatine also allow the determination of creatinine as well as adenosine diphosphate and adenosine triphosphate. PMID:22541827

See, Hong Heng; Schmidt-Marzinkowski, Julia; Pormsila, Worapan; Morand, Réjane; Krähenbühl, Stephan; Hauser, Peter C

2012-05-21

368

[Comparative studies of avian mycoplasmas by flat gel polyacrylamide electrophoresis (author's transl)].  

PubMed

The phenol-acetic-acid extraced cell proteins of Mycoplasma (M.) and Acholeplasma (A.) reference strains (PG31 (M. gallisepticum), PG 16 (M. gallinarum), PG30 (M iners), 17529 (M. meleagridis), WVU 1853 (M. synoviae), 1340 (M. anatis), PG8 and PG9 (A. laidlawii), CKK (Serovar C), DD (Serovar D), WR1 (Serogroup F), 695 (Serogroup I) and 694 (Serogroup L) were anlysed by the flat gel polyacrylamide electrophoresis. With exception of PG8 and PG9 the Coomassie Blue-stained protein patterns show that each of the strains produced reproducible characteristic electrophoretic pattern by which the reference strains could be differentiated. However, before the question could be answered whether the procedure described is suitable to replace the serological species differentiation of avian mycoplasmas, serological and electrophoretic studies of a relevant number of field strain are necessary. PMID:566006

Hinz, K H; Neumann, U

1978-04-01

369

Membrane stabilizer  

DOEpatents

A device is provided for stabilizing a flexible membrane secured within a frame, wherein a plurality of elongated arms are disposed radially from a central hub which penetrates the membrane, said arms imposing alternately against opposite sides of the membrane, thus warping and tensioning the membrane into a condition of improved stability. The membrane may be an opaque or translucent sheet or other material. 10 figs.

Mingenbach, W.A.

1988-02-09

370

DESOXYCORTICOSTERONE ACETATE AND WOUND HEALING  

PubMed Central

The effect of desoxycorticosterone acetate (DCA) on the granulation tissue of healing and healed linear laparotomy wounds was studied in young adult male guinea pigs maintained on a complete diet and on a known intake of ascorbic acid. DCA induces the production of an excessive amount of granulation tissue, as evidenced by a relatively great number of fibroblasts and by a larger amount of ground substance. This effect was accompanied by a slight to moderate lag in the maturation process of both cellular and intercellular elements. These changes were observed when DCA administration was begun 5 days prior to operation, but were less obvious or absent if DCA was injected, beginning on the 5th or 10th postoperative day. The results indicate that the action of DCA on immature, proliferating connective tissue is marked, and is considerably less or absent when connective tissue elements have reached partial or almost complete maturity. The effect of DCA on connective tissue does not appear to rest on the basis of an altered nutritional status. Chemical and histochemical studies of the adrenals suggest that the action of DCA on connective tissue is probably mediated through a disturbance of adrenocortical function, namely an imbalance between hormones of the zona glomerulosa (excess of DCA) and those of the zona fasciculata (deficiency of glucocorticoids). The presence of changes in granulation tissue and the lack of them in mature resting connective tissue of DCA-treated guinea pigs confirm the view that a profound difference in the response mechanism exists between resting and actively proliferating connective tissue.

Pirani, Conrad L.; Stepto, Robert C.; Sutherland, Kenneth

1951-01-01

371

The pharmacology of nomegestrol acetate.  

PubMed

Nomegestrol acetate (NOMAC) is a 19-norprogesterone derivative with high biological activity at the progesterone receptor, a weak anti-androgenic effect, but with no binding to estrogen, glucocorticoid or mineralocorticoid receptors. At dosages of 1.5mg/day or more, NOMAC effectively suppresses gonadotropic activity and ovulation in women of reproductive age. Hemostasis, lipids and carbohydrate metabolism remain largely unchanged. In normal and cancerous human breast cells, NOMAC has shown favorable effects on estrogen metabolism. Like natural progesterone (but in contrast to some other synthetic progestogens), it does not appear stimulate the proliferation of cancerous breast cells. While there has been some experience of the use of NOMAC in combination with estrogens as a hormone replacement therapy, most of the data on the compound are reported in the context of its inclusion as a component of a new contraceptive pill comprising 2.5mg NOMAC combined with 1.5mg estradiol. Because of its strong endometrial efficacy, and due to its high antigonadotropic activity and long elimination half-life (about 50h), the contraceptive efficacy of the new pill is maintained even when dosages are missed. Furthermore, for the first time with a monophasic 24/4 regimen containing estradiol, cyclical stability can be achieved comparable with that obtained using pills containing ethinyl estradiol and progestogens like levonorgestrel or drospirenone. The addition of NOMAC to estradiol means that the beneficial effects of estrogen are not lost, which is of especial importance in relation to the cardiovascular system. On the basis both of its pharmacology and of studies performed during the development of the NOMAC/estradiol pill, involving some 4000 women in total, good long-term tolerability can be expected for NOMAC, although its safety profile is still to be fully ascertained, as the clinical endpoint studies are yet to be completed. PMID:22364709

Ruan, Xiangyan; Seeger, Harald; Mueck, Alfred O

2012-04-01

372

Correlation between acetic acid resistance and characteristics of PQQ-dependent ADH in acetic acid bacteria.  

PubMed

In this study, we compared the growth properties and molecular characteristics of pyrroloquinoline quinone (PQQ)-dependent alcohol dehydrogenase (ADH) among highly acetic acid-resistant strains of acetic acid bacteria. Gluconacetobacter europaeus exhibited the highest resistance to acetic acid (10%), whereas Gluconacetobacter intermedius and Acetobacter pasteurianus resisted up to 6% of acetic acid. In media with different concentrations of acetic acid, the maximal acetic acid production rate of Ga. europaeus slowly increased, but specific growth rates decreased concomitant with increased concentration of acetic acid in medium. The lag phase of A. pasteurianus was twice and four times longer in comparison to the lag phases of Ga. europaeus and Ga. intermedius, respectively. PQQ-dependent ADH activity was twice as high in Ga. europaeus and Ga. intermedius as in A. pasteurinus. The purified enzymes showed almost the same specific activity to each other, but in the presence of acetic acid, the enzyme activity decreased faster in A. pasteurianus and Ga. intermedius than in Ga. europaeus. These results suggest that high ADH activity in the Ga. europaeus cells and high acetic acid stability of the purified enzyme represent two of the unique features that enable this species to grow and stay metabolically active at extremely high concentrations of acetic acid. PMID:16133326

Trcek, Janja; Toyama, Hirohide; Czuba, Jerzy; Misiewicz, Anna; Matsushita, Kazunobu

2006-04-01

373

Immobilization of cellulase in nanofibrous PVA membranes by electrospinning  

Microsoft Academic Search

Electrospinning is a nanofiber-forming process by which either polymer solution or melt is charged to high voltages. With high specific surface area and porous structure, electrospun fibrous membranes are excellent candidates for immobilization of enzymes. In this paper, immobilization of cellulase in nanofibrous poly(vinyl alcohol) (PVA) membranes was studied by electrospinning. PVA and cellulase were dissolved together in an acetic

Lili Wu; Xiaoyan Yuan; Jing Sheng

2005-01-01

374

IMMERSED ULTRAFILTRATION MEMBRANES FOR TREATMENT OF ORGANICALLY LADEN SURFACE WATER  

Microsoft Academic Search

Ultrafiltration membranes are becoming increasingly prevalent in potable water treatment applications. This trend can be attributed to the improved cost effectiveness of membrane systems as compared to conventional treatment technologies and to progressively more stringent water quality regulations. In particular, increased awareness related to the formation of disinfection by-products (DBPs) such as trihalomethanes (THMs) and halo-acetic acids (HAAs) has required

John Van Doesburg; Sophie Pease; Miles Sherman

375

Research and Development of New and Improved Cellulose Ester Membranes.  

National Technical Information Service (NTIS)

The goal of the program was the preparation of membranes for demineralizing brackish waters and seawater with a retention of at least 80% of their initial flux after one year of operation. Two membranes, one made from a blend of cellulose acetates and one...

A. J. Secchi C. W. Saltonstall D. L. Hoernschemeyer O. S. Schaeffler

1973-01-01

376

Basement membrane alterations during development and regression of tubular cysts  

Microsoft Academic Search

Basement membrane alterations during development and regression of tubular cysts. Tubular cysts consisting of dilatation of the collecting ducts at the level of the subcapsular zone of the kidney were induced in newborn rabbits by a single injection of methylprednisolone acetate. We describe here the structural and compositional modifications of the tubular basement membrane (BM) during the formation, growth, and

José L Ojeda; M A Angeles Ros; José M Icardo; Juan A García-Porrero

1990-01-01

377

PERVAPORATION OF ETHANOL-WATER USING CHITOSAN CLAY COMPOSITE MEMBRANE  

Microsoft Academic Search

The pervaporation performance for the separation of ethanol-water azeotrope mixture was assessed by chitosan-clay composite membranes. Composite hydrophilic chitosan membrane was prepared from commercially available chitosan powder. The chitosan powder was dissolved using dilute acetic acid to produce chitosan solution. The chitosan solution was blended with small amount of clay and casted on a porous support which prepared from polysulfone

MOHD GHAZALI MOHD NAWAWI; AZIATUL NIZA SADIKIN; TAN GI GI

378

Capillary electrophoresis of 99mtechnetium radiopharmaceuticals  

Microsoft Academic Search

Diagnostically used 99mTc kit radiopharmaceuticals were analyzed using capillary zone electrophoresis with radioactivity detection: 99mTc-bis(bis(2-ethyloxyethyl)phosphino)ethane (99mTc-Myoview, 99mTc-Tetrofosmin), 99mTc-trans(1,2-bis(dehydro-2,2,5,5,-tetramethyl-3-furanone-4-methylene-amino)ethane)-tris(3-methoxy-1-propyl)phosphine) (99mTc-Technescan Q12, 99mTc-Furifosmin), 99mTc-methoxyisobutylisonitrile (99mTc-MIBI), 99mTc-l,l-ethylenecysteine diethylester dimer (99mTc-ECD), 99mTc-d,l-hexamethylene propyleneamine oxime (99mTc-HMPAO), 99mTc-diethylenetriaminepentaacetic acid (99mTc-DTPA), 99mTc-ethylene hepatobiliary iminodiacetic acid (99mTc-EHIDA), 99mTc-l,l-ethylenecysteine dimer (99mTc-EC), 99mTc-mercaptoacetylglycylglycylglycine (99mTc-MAG3), 99mTc-dimercaptosuccinic acid (99mTc-DMSA), 99mTc-methylene diphosphonate (99mTc-MDP) and 99mNaTcO4. A pressure-driven capillary zone electrophoresis was employed to

R Jankowsky; B Noll; B Johannsen

1999-01-01

379

Analysis of DNA ligation by microchip electrophoresis.  

PubMed

We describe the potential of microchip electrophoresis with a Hitachi SV1100, which can be used to determine DNA sizes between 500 and 5000 bp with good quantification (DNA concentration, <8 ng/l) within 5 min, for the analysis of DNA ligation. On analysis of an electropherogram of a ligation mixture of the pTAC1-T vector and a 789 bp PCR-amplified DNA fragment, the presence of recombinant DNA was easily detected by comparison with an electropherogram obtained without ligase. On analysis of a ligation mixture of pUC19/Eco RI without alkaline phosphatase treatment and a 667 bp Eco RI-digested fragment of foreign DNA, several peaks observed in the electropherogram corresponded to the formation of monomeric and polymeric insert DNAs, self-ligated vector DNA, and recombinant DNA. On the other hand, several peaks were also observed in the electropherogram of the ligation mixture of pUC19/Eco RI with alkaline phosphatase treatment and the 667 bp Eco RI-digested fragment of foreign DNA, the fluorescence intensity corresponding to recombinant DNA apparently being increased. These results indicate the potential of microchip electrophoresis for the analysis of DNA ligation, it offering high resolution in a short time. PMID:20196235

Umemoto, Yoshihiro; Kataoka, Masatoshi; Yatsushiro, Shouki; Yamamura, Shouhei; Ooie, Toshihiko; Kido, Jun-ichi; Yamamoto, Takenori; Shinohara, Yasuo; Baba, Yoshinobu

2010-06-01

380

Fractionation of mineral species by electrophoresis  

NASA Technical Reports Server (NTRS)

The fractionation of fine-grained aggregates into their major components is a problem in many scientific areas including earth and planetary science. Electrophoresis, the transport of electrically charged particles, immersed in a suspension medium, by a direct current field (Bier, 1959), was employed in this study as a means of separating simulated lunar soil into its constituent minerals. In these tests, conducted in a static analytical cylindrical microelectrophoresis apparatus, samples of simulated lunar soil and samples of pure mineral constituents were placed in the chamber; the electrophoretic mobilities of the lunar soil and the individual mineral constituents were measured. In most of the suspension buffers employed separability was indicated, on the basis of differences in mobility, for all the constituent mineral species except ilmenite and pyroxene, which were not efficiently separable in any of the buffers. Although only a few suspension media were employed, the success of this initial study suggests that electrophoresis may be an important mineral fractionation option in fine-grained aggregate processing.

Dunning, J. D.; Herren, B. J.; Tipps, R. W.; Snyder, R. S.

1982-01-01

381

[Electronic microscopy in endodontic electrophoresis efficiency assessment].  

PubMed

The reason for insufficient efficiency of endodontic treatments is a complex structure of root canals system and presence of dentine tubules (DT) in a root dentine. For sterilization and obturation of all spaces in a root canal system the method of cupper-calcium hydroxide (CCH) electrophoresis was developed. The authors proposed more effective method of CCH galvanophoresis by means of galvanic pins based on electrophoresis principles but allowing deep impregnation of the root dentine by nanoparticles of CCH. The purpose of the study was to validate the parameters of root dentine nanoimpregnation by CCH at endodontic galvanophoresis. Material and methods. Research has carried out on 24 removed teeth in laboratory model. The impact of irrigation of root canal and nanoimpregnation duration on the microflora, dentine smear layer, depth of penetration of CCH particles in dentine tubules was studied by scanning electronic microscopy. Results. Irrigation of root canals essentially reduces the amount of microorganisms and eliminates the dentine smear layer. Nanoimpregnation of root dentine by CCH for 1 day results in obtuation of 60-70% of DT up to 100-200 nm, for 1 week - promotes uniform obturation of DT to 35-50 microns. These values proves galvanophoresis to be a useful tool for pulpitis treatment. By nanoimpregnation for 2 weeks DT were filled with nanoparticles of CCH on depth up to 1.2-1.5 mm, and for 4 weeks - up to 2.5 mm. These terms can be recommended for treatment of apical periodontitis. PMID:23715442

Rumiantsev, V A; Rodionova, E G; Denis, A G; Ol'khovskaia, A V; Tsaturova, Iu V

2013-01-01

382

Electrode array detector for microchip capillary electrophoresis.  

PubMed

Selectivity and resolution for analyses conducted using microfluidic devices can be improved by increasing the total number of individual detection elements in the device. Here, a poly(dimethylsiloxane) capillary electrophoresis microchip was fabricated with an integrated electrode array for selective detection of small molecules. Eight individually addressable gold electrodes were incorporated in series after a palladium current decoupler in the separation channel of an electrophoresis microchip. The electrode array device was characterized using a mixture of biologically relevant analytes and xenobiotics: norepinephrine, 4-aminophenol, acetaminophen, uric acid, and 3,4-dihydroxyphenylacetic acid. Separation efficiencies as high as 9000 +/- 1000 plates (n = 3) for 3,4-dihydroxyphenylacetic acid and limits of detection as low as 2.6 +/- 1.2 microM (n = 3) for norepinephrine were obtained using this device. After characterizing the performance of the device, potential step detection was conducted at the array electrodes and selective detection achieved based upon differences in redox potentials for individual analytes. Utilization of potential step detection was particularly advantageous for resolving co-migrating species; resolution of 3,4-dihydroxy-l-phenylalanine from acetaminophen using potential control was demonstrated. Finally, a human urine sample was analyzed using potential step detection to demonstrate the applicability of this device for complex sample analysis. PMID:19238284

Holcomb, Ryan E; Kraly, James R; Henry, Charles S

2009-03-01

383

Photothermal densitometer for reading electrophoresis gels  

US Patent & Trademark Office Database

A densitometer apparatus for evaluating electrophoresis gel samples based on photothermal techniques. In accordance with this invention, electrophoresis gels are characterized by passing a heating light beam through the gel at a particular location. Light absorbed by the presence of staining dyes in that area causes heat evolution which generates a local index of refraction variation or a "thermal lens". A probe beam is passed through the sample in the area of the thermal lens a predetermined period of time after it is generated and the modification to the beam caused by the thermal lens is evaluated. For example, defocusing of the probe beam can be sensed by a detector which receives transmitted light through a limiting aperture. Various means of separating the heating and probe beams are disclosed, including use of separate lasers, crossed beams, modulation by plane of polarization, etc. One embodiment of this invention is particularly adapted for characterizing dry gels in which the heating beam is absorbed by the sample and the probe beam passes across the sample and is modified by a thermal lens generated in the air above the sample. Several embodiments are related to means for offsetting the probe beam from the heating beam for use with samples that are swept by the photothermal techniques in accordance with this invention offer advantages in terms of sensitivity over conventional transmission-type densitometers. These advantages enable increased sensitivity and facilitate the use of simplified staining techniques.

1990-07-03

384

Density Functional Theory Study of Selective Deacylation of Aromatic Acetate in the Presence of Aliphatic Acetate under Ammonium Acetate Mediated Conditions.  

PubMed

Aromatic acetates can be selectively deprotected in the presence of aliphatic acetates under ammonium acetate mediated condition. B3LYP/6-31++G** level of theory was demonstrated to be successfully used to model the relative reaction rates for deacylation reactions for aliphatic and aromatic ester systems. On the basis of the mechanistic studies, acetate anion is most likely to be the active catalyst for the ester deacylation reactions under ammonium acetate mediated condition. PMID:24956355

Xia, Shijing; Zhang, Haoyu

2014-07-01

385

Pervaporation with chitosan membranes. I. Separation of water from ethylene glycol by a chitosan\\/polysulfone composite membrane  

Microsoft Academic Search

A chitosan\\/polysulfone composite membrane was prepared. The preparation procedure involved dissolution of chitosan in dilute aqueous acetic acid to form chitosan salt, coating of the chitosan salt solution on a porous polysulfone substrate, and regeneration of chitosan by alkaline treatment. The membrane was tested for selective removal of water from aqueous ethylene glycol solutions by pervaporation. The effects of operating

Xianshe Feng; Robert Y. M. Huang

1996-01-01

386

Acetate Causes Alcohol Hangover Headache in Rats  

PubMed Central

Background The mechanism of veisalgia cephalgia or hangover headache is unknown. Despite a lack of mechanistic studies, there are a number of theories positing congeners, dehydration, or the ethanol metabolite acetaldehyde as causes of hangover headache. Methods We used a chronic headache model to examine how pure ethanol produces increased sensitivity for nociceptive behaviors in normally hydrated rats. Results Ethanol initially decreased sensitivity to mechanical stimuli on the face (analgesia), followed 4 to 6 hours later by inflammatory pain. Inhibiting alcohol dehydrogenase extended the analgesia whereas inhibiting aldehyde dehydrogenase decreased analgesia. Neither treatment had nociceptive effects. Direct administration of acetate increased nociceptive behaviors suggesting that acetate, not acetaldehyde, accumulation results in hangover-like hypersensitivity in our model. Since adenosine accumulation is a result of acetate formation, we administered an adenosine antagonist that blocked hypersensitivity. Discussion Our study shows that acetate contributes to hangover headache. These findings provide insight into the mechanism of hangover headache and the mechanism of headache induction.

Maxwell, Christina R.; Spangenberg, Rebecca Jay; Hoek, Jan B.; Silberstein, Stephen D.; Oshinsky, Michael L.

2010-01-01

387

Ultrasonic Relaxation in Aqueous Acetic Acid Solutions.  

National Technical Information Service (NTIS)

Ultrasonic absorption measurements have been made in aqueous acetic solutions at 15 to 85 MHz using pulse echo and pulse send-receive techniques. A weighted nonlinear regression method has been developed for the computation of the relaxation parameters. A...

L. G. Jackopin E. Yeager

1971-01-01

388

Water dispersible microbicidal cellulose acetate phthalate film  

Microsoft Academic Search

BACKGROUND: Cellulose acetate phthalate (CAP) has been used for several decades in the pharmaceutical industry for enteric film coating of oral tablets and capsules. Micronized CAP, available commercially as \\

A Robert Neurath; Nathan Strick; Yun-Yao Li

2003-01-01

389

Isolation and partial characterization of Borrelia burgdorferi inner and outer membranes by using isopycnic centrifugation.  

PubMed Central

In order to characterize the protein composition of the outer membrane of Borrelia burgdorferi, we have isolated inner and outer membranes by using discontinuous sucrose density step gradients. Outer and inner membrane fractions isolated by this method contained less than 1 and 2%, respectively, of the total lactate dehydrogenase activity (soluble marker) in cell lysate. More importantly, the purified outer membranes contained less than 4% contamination by the C subunit of F1/F0 ATPase (inner membrane marker). Very little flagellin protein was present in the outer membrane sample. This indicated that the outer membranes were relatively free of contamination by cytoplasmic, inner membrane or flagellar components. The outer membrane fractions (rho = 1.19 g/cm3) contained 0.15 mg (dry weight) of protein per mg. Inner membrane samples (rho = 1.12 g/cm3) contained 0.60 mg (dry weight) of protein per mg. Freeze-fracture electron microscopy revealed that the outer membrane vesicles contained about 1,700 intramembranous particles per micron 2 while inner membrane densities for inner and outer membranes. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and nonequilibrium pH gel electrophoresis-SDS-PAGE analyses of inner and outer membrane samples revealed several proteins unique to the inner membrane and 20 proteins that localized specifically to the outer membrane. This analysis clearly shows that the inner and outer membranes isolated by this technique are unique structures. Images

Bledsoe, H A; Carroll, J A; Whelchel, T R; Farmer, M A; Dorward, D W; Gherardini, F C

1994-01-01

390

Determination of sulfonylurea herbicides in water by capillary electrophoresis and by liquid chromatography/mass spectrometry.  

PubMed

A capillary electrophoresis (CE) method and an electrospray ionization (ESI) liquid chromatography/mass spectrometry (LC/MS) confirmatory method were developed to analyze 12 sulfonylurea herbicides and one sulfonamide (Flumetsulam) in runoff water. The water used for fortification was collected from a local marsh that contained high levels of potentially interfering compounds. Good recoveries and adequate sensitivity at the 0.2 ppb level (limit of quantitation) were obtained. A portion of the water was acidified and extracted with reversed-phase solid-phase extraction (SPE). Extracts were cleaned up with a tandem system consisting of a strong-anion exchange SPE cartridge stacked on an alumina SPE cartridge. CE/ultraviolet quantitation was achieved by capillary zone electrophoresis at pH 4.75 with 50 mM ammonium acetate buffer and an acetonitrile modifier. ESI LC/MS quantitation was achieved by using a time-scheduled selective-ion monitoring (positive mode) of the M + H ions for each compound. The extraction/cleanup procedure provided extracts such that in-source collision-induced dissociation gave product ions for confirmation at the 0.2 ppb fortification level. PMID:9086596

Krynitsky, A J

1997-01-01

391

Nomegestrol acetate/estradiol: in oral contraception.  

PubMed

Nomegestrol acetate/estradiol is a combined oral contraceptive with approval in many countries. This fixed-dose combination tablet contains nomegestrol acetate, a highly selective progestogen, and estradiol, a natural estrogen. It is the first monophasic combined oral contraceptive to contain estradiol, and is taken in 28-day cycles, consisting of 24 active therapy days with 4 placebo days (i.e. 24/4-day cycles). In two large, 1-year, randomized, open-label, multicentre, phase III trials in healthy adult women (aged 18-50 years), nomegestrol acetate/estradiol was at least as effective as drospirenone/ethinylestradiol as contraceptive therapy, as the pregnancy rates in women aged 18-35 years (primary efficacy population) in terms of the Pearl Index (primary endpoint) were numerically lower with nomegestrol acetate/estradiol, although the between-group difference was not statistically significant. In both trials, nomegestrol acetate/estradiol was given in a 24/4-day cycle, and drospirenone/ethinylestradiol was given in a 21/7-day cycle. The criteria for using condoms in case of forgotten doses were less stringent in the nomegestrol acetate/estradiol group than in the drospirenone/ethinylestradiol group. Nomegestrol acetate/estradiol therapy for up to 1 year was generally well tolerated in healthy adult women, with an acceptable tolerability profile in line with that expected for a combined oral contraceptive. The most commonly reported adverse events were acne and abnormal withdrawal bleeding (most often shorter, lighter or absent periods). Overall, compared with drospirenone/ethinylestradiol, nomegestrol acetate/estradiol appeared to be associated with less favourable acne-related outcomes, and shorter, lighter or absent periods. PMID:22950535

Yang, Lily P H; Plosker, Greg L

2012-10-01

392

Precision and reliability of paraprotein determinations by high-resolution agarose gel electrophoresis.  

PubMed

Agarose gel electrophoresis has recently replaced cellulose acetate electrophoresis as the preferred technique for monitoring paraprotein levels in patients with plasma cell dyscrasias. The authors studied the accuracy and precision of this method for paraprotein determination. Twenty-seven serum samples with paraprotein concentrations ranging from 5 to 73 g/L were aliquotted and assayed on 20 separate occasions, and the mean and standard deviation for the paraprotein concentration in each serum was established. Linear regression analysis showed that the standard deviation of paraprotein concentration (SD) increased as a function of paraprotein concentration (PC). For IgG paraproteins, the regression equation was SD = 0.041 (PC) + 1.06; R = 0.942; standard error = 0.32. For non-IgG paraproteins the equation was SD = 0.101 (PC) - 0.04; R = 0.851; standard error = 0.5. The accuracy of paraprotein determinations by the agarose gel electrophoretic technique was assessed by comparison with values obtained with the use of a previously validated enzyme-linked immunosorbent assay (ELISA) method for quantitation of IgG subclasses. Results obtained by the two methods were similar and highly correlated: (concentration by electrophoresis) = 0.921 (concentration by ELISA) + 0.46; R = 0.988; standard error = 0.34. The laser densitometric scanning procedure showed a loss of linearity above 60 g/L, indicating the need to dilute sera with very high paraprotein concentrations in order to obtain accurate results. A table is presented that should help pathologists who interpret such scans to determine whether small changes in paraprotein measurements occurring over time represent true changes in paraprotein concentration or merely reflect the analytic variability inherent in the technique. PMID:2929498

Stemerman, D; Papadea, C; Martino-Saltzman, D; O'Connell, A C; Demaline, B; Austin, G E

1989-04-01

393

Toxic Membrane Fractions from Mycoplasma fermentans1  

PubMed Central

A recent isolate of Mycoplasma fermentans (strain K10, from human leukemic bone marrow) induced a lethal toxicity syndrome in mice. High doses of both viable and inactivated cells were toxic when injected intraperitoneally. Whole lysates and membranes from osmotically shocked cells killed mice, but cytoplasm did not. When membranes were dissolved in detergents and reaggregated by dialysis in the presence of Mg2+, the lipid-protein complex thus formed was toxic. Lipids extracted from membranes with chloroform-methanol did not kill mice. Protein-rich fractions (obtained by reaggregation plus acetone washes or ammonium sulfate precipitation of dissolved membranes) were also not toxic. No qualitative differences in proteins from three toxic isolates and three nontoxic laboratory strains of M. fermentans were detectable by polyacrylamide gel electrophoresis. The toxic factor contained in reaggregated membranes was heat-stable but sensitive to Pronase, trypsin, and lipase. Images

Gabridge, Michael G.; Murphy, William H.

1971-01-01

394

Fluorescence quenching of etilefrine by acetate anion  

NASA Astrophysics Data System (ADS)

Acid dissociation in the excited state of antihypotensor drug etilefrine [2-(ethylamino1-3-hydroxyphenyl)ethanol] is studied. Fluorescence of etilefrine decreases at pH<7 and is related to phenolic group dissociation. However, intensity of etilefrine fluorescence diminishes as the concentration of the acetate anion increases at pH>7. Analyses of the absorption and fluorescence spectra of aqueous solutions of etilefrine in the presence of acetate anions have been made. Considering the existence of an equilibrium in the excited state the values of 3.47×10 -9 and 0.216×10 -9 M -1 s -1 have been obtained for the rate constants for direct and inverse reactions, respectively. Moreover, the lifetime ( ?0'=0.58×10 -9 s) and quantum yield (0.01) of non-protonated etilefrine have been determined. Our results seem to support the existence of a dynamic quenching process based on a proton transfer mechanism induced by acetate anions. This process could represent a serious inconvenience in analytical fluorimetric techniques taking into account that the acetic acid/acetate pair is commonly used as a buffer. Additional fluorescence quenching by H + ions could be involved in acid aqueous mediums. At high concentrations of acetic acid, a value of 2.98×10 -9 M -1 s -1 for the bimolecular constant for the quenching by H + has been calculated.

Quintero Osso, B.; Carazo Rodríguez, F. M.; Morales Domingo, J. J.; Cabeza González, M. C.; Thomas Gómez, J.

1999-02-01

395

Density data for copolymer systems: butyl acrylate\\/vinyl acetate homo- and copolymerization in ethyl acetate  

Microsoft Academic Search

A study was performed to provide precise density data, badly needed for on-line measurements and control of polymerization reactors, e.g. for densimetry studies. Data was obtained for one copolymer of butyl acrylate\\/vinyl acetate, the homopolymers of vinyl acetate and butyl acrylate, plus the two monomers and ethyl acetate. In addition, the hypothesis of the linear dependence of the density of

I Barudio; G Févotte; T. F McKenna

1999-01-01

396

Self-supported poly(methyl methacrylate–acrylonitrile–vinyl acetate)-based gel electrolyte for lithium ion battery  

Microsoft Academic Search

Self-supported gel polymer electrolyte (GPE) was prepared based on copolymer, poly(methyl methacrylate–acrylonitrile–vinyl acetate) (P(MMA–AN–VAc)). The copolymer P(MMA–AN–VAc) was synthesized by emulsion polymerization and the copolymer membrane was prepared through phase inversion. The structure and the performance of the copolymer, the membrane and the GPE were characterized by FTIR, NMR, SEM, XRD, DSC\\/TG, LSV, CA, and EIS. It is found that

Y. H. Liao; D. Y. Zhou; M. M. Rao; W. S. Li; Z. P. Cai; Y. Liang; C. L. Tan

2009-01-01

397

High-Throughput Capillary-Electrophoresis Analysis of the Contents of Single Mitochondria  

PubMed Central

We present a technique for labeling the contents of acidic organelles and rapidly releasing, separating, and detecting their labeled contents with laser-induced fluorescence. We have performed solution-phase separation of the contents of single mitochondria and single 100 nm vesicles, which represents a demonstration of an analyzed volume of ~1 attoliter. Our strategy to label the acidic contents of the mitochondrion relies on the use of the membrane-permeable dye, Oregon Green diacetate succinimidyl ester, and a membrane-permeable base to raise intra-mitochondrial pH. In order to measure the contents, we utilized a glass microfluidic chip and high voltage gradient for millisecond capillary-electrophoresis separation after single-mitochondrion photolysis. We observed heterogeneity among a population of mitochondria with respect to a constituent chemical component.

Allen, Peter B.; Doepker, Byron R.; Chiu, Daniel T.

2009-01-01

398

Dating silk by capillary electrophoresis mass spectrometry.  

PubMed

A new capillary electrophoresis mass spectrometry (CE-MS) technique is introduced for age estimation of silk textiles based on amino acid racemization rates. With an L to D conversion half-life of ~2500 years for silk (B. mori) aspartic acid, the technique is capable of dating silk textiles ranging in age from several decades to a few-thousand-years-old. Analysis required only ~100 ?g or less of silk fiber. Except for a 2 h acid hydrolysis at 110 °C, no other sample preparation is required. The CE-MS analysis takes ~20 min, consumes only nanoliters of the amino acid mixture, and provides both amino acid composition profiles and D/L ratios for ~11 amino acids. PMID:21913691

Moini, Mehdi; Klauenberg, Kathryn; Ballard, Mary

2011-10-01

399

Novel absorption detection techniques for capillary electrophoresis  

SciTech Connect

Capillary electrophoresis (CE) has emerged as one of the most versatile separation methods. However, efficient separation is not sufficient unless coupled to adequate detection. The narrow inner diameter (I.D.) of the capillary column raises a big challenge to detection methods. For UV-vis absorption detection, the concentration sensitivity is only at the {mu}M level. Most commercial CE instruments are equipped with incoherent UV-vis lamps. Low-brightness, instability and inefficient coupling of the light source with the capillary limit the further improvement of UV-vis absorption detection in CE. The goals of this research have been to show the utility of laser-based absorption detection. The approaches involve: on-column double-beam laser absorption detection and its application to the detection of small ions and proteins, and absorption detection with the bubble-shaped flow cell.

Xue, Y.

1994-07-27

400

[Chiral separation of dipeptides by capillary electrophoresis].  

PubMed

Peptides are increasingly used as pharmaceutical agents. Many small peptides are the essential compounds in biological systems. Direct chiral separation of dipeptide derivatives using 9-(2-carbazole) ethyl chloroformate (CEOC) as the derivatizing agent by capillary electrophoresis (CE) with beta-cyclodextrin (beta-CD) and sodium deoxycholate (SDC) as chiral selectors has been developed. It has been well recognized that the combination of the binary selectors can enhance the selectivity and resolution instead of either beta-CD or SDC alone. The molar ratio of the binary chiral selectors, the buffer concentration and pH of Tris-H3PO4, organic modifier were studied and optimized. Complete chiral separations for 14 dipeptide derivatives using beta-CD and SDC as binary chiral selectors were obtained. The results indicated that each pair of D/L chiral resolution was more than 3.63, and the highest resolution for Gly-Ala was 43.14. PMID:16830473

Cheng, Yan; Bai, Min; Wang, Xinmei; Ming, Yongfei; You, Jinmao

2006-03-01

401

Flow structure in continuous flow electrophoresis chambers  

NASA Technical Reports Server (NTRS)

There are at least two ways that hydrodynamic processes can limit continiuous flow electrophoresis. One arises from the sensitivity of the flow to small temerature gradients, especially at low flow rates and power levels. This sensitivity can be suppressed, at least in principle, by providing a carefully tailored, stabilizing temperature gradient in the cooling system that surrounds the flow channel. At higher power levels another limitation arises due to a restructuring of the main flow. This restructuring is caused by buoyancy, which is in turn affected by the electro-osmotic crossflow. Approximate solutions to appropriate partial differential equations have been computed by finite difference methods. One set of results is described here to illustrate the strong coupling between the structure of the main (axial) flow and the electro-osmotic flow.

Deiber, J. A.; Saville, D. A.

1982-01-01

402

The effects of electroendosmosis in agarose electrophoresis.  

PubMed

The effects of agarose gel strips without and with 0.03 m(r) electroendosmosis (EEO) on isoelectric focusing (IEF) were studied. It is shown that only agarose without EEO can be used for IEF. The effects of electrode buffer strips using agarose with different EEO of 0, 0.03, 0.08, 0.20 m(r) on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and native PAGE were also studied. It apparently did not affect SDS-PAGE, but affected native PAGE to a certain extent. The higher the EEO value was, the more water was present on the agarose gel strip during a separation. Agarose gel strips with an EEO of 0.2 m(r) are not suitable as electrode buffer strips for native PAGE. PMID:9694271

Guo, Y; Li, X; Fang, Y

1998-06-01

403

Antigen-antibody interactions in capillary electrophoresis.  

PubMed

Immunoreactions in combination with separations by capillary electrophoresis (CE) are increasingly being used to quantitate specific analytes in biological fluids. Both competitive and non-competitive approaches have been used for the purpose and, in selected cases, now compare favorably with conventional quantitative immunoassays with respect to concentration limits of detection. CE is also a useful method to evaluate antigen-antibody binding on-line and offers unique possibilities for binding constant estimates, also for weakly binding antibodies and antibody fragments. In this review we cover recent developments in the use of antigen-antibody interactions in conjunction with CE and conclude that continued development of miniaturization, on-line preconcentration and more sensitive detection schemes will contribute to the further dissemination of CE-based immunoassays building on already established affinity CE approaches. PMID:11939562

Heegaard, Niels H H; Kennedy, Robert T

2002-02-25

404

Applications of affinity interactions in capillary electrophoresis.  

PubMed

Capillary electrophoresis (CE) has proven useful for the study of reversible molecular interactions. This is because highly efficient and reproducible separations take place in an environment where molecular interactions may contribute to selectivity without being inhibited by adverse buffer conditions. Affinity CE may be used to estimate quantitative binding data (binding constants and in some cases binding stoichiometries and rate constants) for various molecular interactions. Specific binding interactions (e.g., based on antibodies or aptamers) may also be utilized to quantitatively measure specific analytes using CE. Applications within these areas are here reviewed with focus on the last three years and with emphasis on novel concepts as well as innovative methodology and technology. It is concluded that the affinity CE approach is of growing versatility and will continue to play an integral role in discovering, characterizing, and exploiting biomolecular interactions. PMID:14661223

Heegaard, Niels H H

2003-12-01

405

Study of perrhenate reduction by capillary electrophoresis.  

PubMed

The influence of perrhenate concentration, the concentration of the reducing agent and pH of the reaction mixture on the yield of perrhenate reduction were studied to find a possibility to decrease the stannous chloride concentration in the reaction mixture without negative changes on the yield of perrhenate reduction. Britton-Robinson buffer solutions were selected as the background electrolytes because of their buffering capacity in a wide pH interval. The highest degree of perrhenate reduction was obtained at pH 2 at perrhenate concentrations ranging from 10(-4) to 10(-3) mol/L. The stability of reduced rhenium against pH change from 2 to 5.5 and against dilution of rhenium in the reaction mixture to the concentration suitable for the application in radiotherapy were studied as well. The results obtained by capillary electrophoresis and by thin-layer chromatography with radiometric detection were compared. PMID:11840530

Kohlícková-Koudelková, Michaela; Jedináková-Krízová, Vera; Deyl, Zdenek

2002-01-01

406

High sensitivity radiation detector for capillary electrophoresis  

SciTech Connect

Capillary electrophoresis is an important new instrumental technique capable of high resolution separation and analysis of small quantities of nucleotides, amino acids, peptides, and proteins with very high efficiency and throughput. The unprecedented sensitivity of this technique will be useful for such new applications as in vivo labeling and identification of trace substances and single cell work. The principle limitation of this technique for radiolabeled molecules has been identified as the sensitivity of the detector, primarily due to the small sample volume (< 1 nl) and the short residence time of the sample in the detector (< 3 sec). The authors have developed a novel high-sensitivity CdTe solid-state detector used for detection of [sup 32]P-labeled biomolecules with unprecedented sensitivity. This detector can be easily retrofitted into existing CE apparatus.

Gordon, J.S.; Vasile, S.; Hazlett, T.; Squillante, M. (Radiation Monitoring Devices, Inc., Watertown, MA (United States))

1993-08-01

407

Combined electrophoresis-electrospray interface and method  

DOEpatents

A system and method for analyzing molecular constituents of a composition sample include: forming a solution of the sample, separating the solution by capillary electrophoresis into an eluent of constituents longitudinally separated according to their relative electrophoretic mobilities, electrospraying the eluent to form a charged spray in which the molecular constituents have a temporal distribution; and detecting or collecting the separated constituents in accordance with the temporal distribution in the spray. A first high-voltage (e.g., 5--100 kVDC) is applied to the solution. The spray is charged by applying a second high voltage (e.g.,{+-}2--8 kVDC) between the eluent at the capillary exit and a cathode spaced in front of the exit. A complete electrical circuit is formed by a conductor which directly contacts the eluent at the capillary exit, or by conduction through a sheath electrode discharged in an annular sheath flow about the capillary exit. 21 figs.

Smith, R.D.; Udseth, H.R.; Olivares, J.A.

1994-10-18

408

Combined electrophoresis-electrospray interface and method  

DOEpatents

A system and method for analyzing molecular constituents of a composition sample includes: forming a solution of the sample, separating the solution by capillary electrophoresis into an eluent of constituents longitudinally separated according to their relative electrophoretic mobilities, electrospraying the eluent to form a charged spray in which the molecular constituents have a temporal distribution; and detecting or collecting the separated constituents in accordance with the temporal distribution in the spray. A first high-voltage (e.g., 5-100 KVDC) is applied to the solution. The spray is charged by applying a second high voltage (e.g., .+-.2-8 KVDC) between the eluent at the capillary exit and a cathode spaced in front of the exit. A complete electrical circuit is formed by a conductor which directly contacts the eluent at the capillary exit, or by conduction through a sheath electrode discharged in an annular sheath flow about the capillary exit.

Smith, Richard P. (Richland, WA); Udseth, Harold R. (Richland, WA); Olivares, Jose A. (North Augusta, SC)

1989-01-01

409

Combined electrophoresis-electrospray interface and method  

DOEpatents

A system and method for analyzing molecular constituents of a composition sample includes: forming a solution of the sample, separating the solution by capillary electrophoresis into an eluent of constituents longitudinally separated according to their relative electrophoretic mobilities, electrospraying the eluent to form a charged spray in which the molecular constituents have a temporal distribution; and detecting or collecting the separated constituents in accordance with the temporal distribution in the spray. A first high-voltage (e.g., 5--100 kVDC) is applied to the solution. The spray is charged by applying a second high voltage (e.g., [+-]2--8 kVDC) between the eluent at the capillary exit and a cathode spaced in front of the exit. A complete electrical circuit is formed by a conductor which directly contacts the eluent at the capillary exit, or by conduction through a sheath electrode discharged in an annular sheath flow about the capillary exit. 21 figs.

Smith, R.P.; Udseth, H.R.; Olivares, J.A.

1989-12-05

410

Combined electrophoresis-electrospray interface and method  

DOEpatents

A system and method for analyzing molecular constituents of a composition sample includes: forming a solution of the sample, separating the solution by capillary electrophoresis into an eluent of constituents longitudinally separated according to their relative electrophoretic mobilities, electrospraying the eluent to form a charged spray in which the molecular constituents have a temporal distribution; and detecting or collecting the separated constituents in accordance with the temporal distribution in the spray. A first high-voltage (e.g., 5-100 KVDC) is applied to the solution. The spray is charged by applying a second high voltage (e.g., .+-.2-8 KVDC) between the eluent at the capillary exit and a cathode spaced in front of the exit. A complete electrical circuit is formed by a conductor which directly contacts the eluent at the capillary exit, or by conduction through a sheath electrode discharged in an annular sheath flow about the capillary exit.

Smith, Richard D. (Richland, WA); Udseth, Harold R. (Richland, WA); Olivares, Jose A. (Los Alamos, NM)

1994-01-01

411

Hybrid slab-microchannel gel electrophoresis system  

DOEpatents

A hybrid slab-microchannel gel electrophoresis system is described. The hybrid system permits the fabrication of isolated microchannels for biomolecule separations without imposing the constraint of a totally sealed system. The hybrid system is reusable and ultimately much simpler and less costly to manufacture than a closed channel plate system. The hybrid system incorporates a microslab portion of the separation medium above the microchannels, thus at least substantially reducing the possibility of non-uniform field distribution and breakdown due to uncontrollable leakage. A microslab of the sieving matrix is built into the system by using plastic spacer materials and is used to uniformly couple the top plate with the bottom microchannel plate. 4 figs.

Balch, J.W.; Carrano, A.V.; Davidson, J.C.; Koo, J.C.

1998-05-05

412

A centrifugal method for the evaluation of polymer membranes for reverse osmosis  

NASA Technical Reports Server (NTRS)

A rapid and simple method employing the laboratory centrifuge shows promise for evaluation of membrane performance during reverse osmosis. Results are presented for cellulose acetate membranes for rejection of salt and urea dissolved solids. Implications of the study are to rapid screening of membrane performance, use in laboratories with limited facilities, and possible space waste water purification.

Hollahan, J. R.; Wydeven, T.; Mccullough, R. P.

1973-01-01

413

The role of membrane morphology on ultrafiltration for natural organic matter removal  

Microsoft Academic Search

Natural Organic Matter (NOM) is abundant in natural waters and is one of the major fouling agents during membrane filtration of surface water. This work addresses the evaluation of the influence of the membrane pore size on the permeation characteristics of humic acid solutions. Five cellulose acetate laboratory made membranes were prepared by the phase inversion method covering a wide

Ana Rita Costa; Maria Norberta de Pinho

2002-01-01

414

Investigating Membranes  

NSDL National Science Digital Library

While not organic in nature, quick-"growing" artificial membranes can be a profound visual aid when teaching students about cellular processes and the chemical nature of membranes. Students are often intrigued when they see biological and chemical concept

Mccallister, Gary; Zrelak, Yoshi

2009-09-01

415

Capillary electrophoresis for short chain organic acids in faeces Reference values in a Mediterranean elderly population.  

PubMed

There is increasing evidence that gut microflora and fermentation processes in the large intestine are important for health, and that health-promoting effects are mediated by fermentation products. Usually analytical methods for these compounds are tedious. A simple and rapid procedure of aqueous extraction from the stools has been optimized. After extraction, an aliquot of the aqueous layer was directly injected into the capillary electrophoresis equipment. Oxalic, formic, fumaric, 2-ketoglutaric, succinic, citric, acetic, propionic, 2-ketoisovaleryc, butyric, isovaleric lactic, glyceric 2-hydroxybutyric, and valeric acids were separated and identified. Electrophoretic conditions were: phosphate buffer 234 mM pH 6.10 with 12% (v/v) methanol with a coated capillary at -10 kV of applied potential. The method was validated for a representative group of compounds: acetic, propionic butyric, 2-hydroxybutiric, isovaleric, and oxalic acids, including the comparison of results with ionic chromatography. Finally 136 samples from healthy humans aged 60-80, both male and female living in Spain, were measured. They could be used as reference values for further studies. PMID:18055154

Garcia, A; Olmo, B; Lopez-Gonzalvez, A; Cornejo, L; Rupérez, F J; Barbas, C

2008-01-22

416

Two-dimensional Gel Electrophoresis (2DE)  

NASA Astrophysics Data System (ADS)

The chemical compounds, which are present in the environment, increasingly cause bad effects on health. The most serious effects are tumors and various mutations at the cellular level. Such compounds, from the analytical point of view, can serve the function of biomarkers, constituting measurable changes in the organism's cells and biochemical processes occurring therein. The challenge of the twenty-first century is therefore searching for effective and reliable methods of identification of biomarkers as well as understanding bodily functions, which occur in living organisms at the molecular level. The irreplaceable tool for these examinations is proteomics, which includes both quality and quantity analysis of proteins composition, and also makes it possible to learn their functions and expressions. The success of proteomics examinations lies in the usage of innovative analytical techniques, such as electromigration technique, two-dimensional electrophoresis in polyacrylamide gel (2D PAGE), liquid chromatography, together with high resolution mass spectrometry and bio-informatical data analysis. Proteomics joins together a number of techniques used for analysis of hundreds or thousands of proteins. Its main task is not the examination of proteins inside the particular tissue but searching for the differences in the proteins' profile between bad and healthy tissues. These differences can tell us a lot regarding the cause of the sickness as well as its consequences. For instance, using the proteomics analysis it is possible to find relatively fast new biomarkers of tumor diseases, which in the future will be used for both screening and foreseeing the course of illness. In this chapter we focus on two-dimensional electrophoresis because as it seems, it may be of enormous importance when searching for biomarkers of cancer diseases.

K?odzi?ska, Ewa; Buszewski, Bogus?aw

417

Phorbol Myristate Acetate Inhibits Anti-IgM-Mediated Signaling in Resting B Cells  

Microsoft Academic Search

Cross-linking the membrane immunoglobulins of resting B cells leads to activation as judged by increased inositol phospholipid metabolism, intracellular free calcium concentration ([Ca2+]i), and cell volume. Such activated B cells enter S phase in the presence of B-cell stimulatory factor 1. Phorbol myristate acetate (PMA) is a potent inhibitor of anti-IgM- and anti-IgD-stimulated B-cell responses. In B cells concentrations of

Junichiro Mizuguchi; Michael A. Beaven; Jane Hu Li; William E. Paul

1986-01-01

418

Loading of amphipathic weak acids into liposomes in response to transmembrane calcium acetate gradients.  

PubMed

We describe a novel procedure to load amphipathic weak acid molecules into preformed liposomes. Differences in calcium acetate concentrations across the liposomal membrane induce an increase of the internal pH. This pH imbalance serves as an efficient driving force to load and accumulate weak acids (5(6)-carboxyfluorescein and nalidixic acid) inside the lipid vesicles. The mechanism of loading and the relevance of the method in drug delivery systems are discussed. PMID:8541297

Clerc, S; Barenholz, Y

1995-12-13

419

Loading of amphipathic weak acids into liposomes in response to transmembrane calcium acetate gradients  

Microsoft Academic Search

We describe a novel procedure to load amphipathic weak acid molecules into preformed liposomes. Differences in calcium acetate concentrations across the liposomal membrane induce an increase of the internal pH. This pH imbalance serves as an efficient driving force to load and accumulate weak acids (5(6)-carboxyfluorescein and nalidixic acid) inside the lipid vesicles. The mechanism of loading and the relevance

Stéphane Clerc; Yechezkel Barenholz

1995-01-01

420

Temperature dependent FTIR spectroscopic study of the interaction of ?-tocopherol and ?-tocopheryl acetate with phospholipid bilayers  

NASA Astrophysics Data System (ADS)

FTIR spectroscopy has been employed in order to investigate ?-tocopherol (?-T) and ?-tocopheryl acetate (?-TA) induced effects on the molecular organization of dimyristoyl- L-?-phosphatidylcholine (DMPC) bilayers, at various temperatures and concentrations. It was concluded that ?-T interacts much more strongly than ?-TA, indicating that ?-T has a more polar location in the membrane than ?-TA. The observed changes in the carbonyl and phosphate group vibrational modes of DMPC on addition of ?-T or ?-TA are discussed

Akyüz, S.; Davies, J. E. D.

1997-08-01

421

Unified Theory for Gel Electrophoresis and Gel Filtration  

Microsoft Academic Search

Unified theory for gel electrophoresis and gel filtration: The behavior of macromolecules in gel filtration and gel electrophoresis may be predicted from Ogston's model for a random meshwork of fibers. This model has been generalized to apply to nonspherical molecules and to several gel types. The model provides equations for inter-relationships between mobility, partition coefficient, gel concentration, and molecular radius;

David Rodbard; Andreas Chrambach

1970-01-01

422

Electrophoresis: The march of pennies, the march of dimes  

Microsoft Academic Search

The present review encompasses ca. 65 years of history of developments in electrokinetic separations, taking as a starting point the year 1937, i.e. the official launching of Tiselius’ moving boundary electrophoresis (MBE). The 1950s have been particularly rich in introducing novel methodologies in zone electrophoresis (ZE), thus bringing about the decline of MBE. Among them of extraordinary importance was the

Pier Giorgio Righetti

2005-01-01

423

Gel Electrophoresis on a Budget to Dye for  

ERIC Educational Resources Information Center

Gel electrophoresis is one of the most important tools used in molecular biology and has facilitated the entire field of genetic engineering by enabling the separation of nucleic acids and proteins. However, commercial electrophoresis kits can cost up to $800 for each setup, which is cost prohibitive for most classroom budgets. This article…

Yu, Julie H.

2010-01-01

424

Protein fouling of surface-modified polymeric microfiltration membranes  

Microsoft Academic Search

The effects of varying morphology and surface chemistry on protein fouling of microfiltration membranes were investigated. In part I of the study, on the effects of varying morphology, results show that 0.2 ?m track-etched polycarbonate (PC) membranes internally foul, with external fouling becoming the dominant means of fouling only at later times. A 0.2 ?m cellulose acetate (CA) membrane showed

Jeffrey Mueller; Robert H. Davis

1996-01-01

425

Reactive oxygen species mediate tumor necrosis factor alpha-converting, enzyme-dependent ectodomain shedding induced by phorbol myristate acetate  

Microsoft Academic Search

Ectodomain shedding of cell surface membrane-anchoring proteins is an important process in a wide variety of physiological events(1, 2). Tumor necrosis factor ? (TNF-? ) converting enzyme (TACE) is the first discovered mammalian sheddase responsible for cleavage of several important surface proteins, including TNF-? , TNF p75 receptor, L-selectin, and transforming growth factor-? . Phorbol myristate acetate (PMA) has long

Zili Zhang; Peter Oliver; Jack R. Lancaster; Paul O. Schwarzenberger; Mahesh S. Joshi; John Cork; Jay K. Kolls

2000-01-01

426

Direct Detection of the Acetate-forming Activity of the Enzyme Acetate Kinase  

PubMed Central

Acetate kinase, a member of the acetate and sugar kinase-Hsp70-actin (ASKHA) enzyme superfamily1-5, is responsible for the reversible phosphorylation of acetate to acetyl phosphate utilizing ATP as a substrate. Acetate kinases are ubiquitous in the Bacteria, found in one genus of Archaea, and are also present in microbes of the Eukarya6. The most well characterized acetate kinase is that from the methane-producing archaeon Methanosarcina thermophila7-14. An acetate kinase which can only utilize PPi but not ATP in the acetyl phosphate-forming direction has been isolated from Entamoeba histolytica, the causative agent of amoebic dysentery, and has thus far only been found in this genus15,16. In the direction of acetyl phosphate formation, acetate kinase activity is typically measured using the hydroxamate assay, first described by Lipmann17-20, a coupled assay in which conversion of ATP to ADP is coupled to oxidation of NADH to NAD+ by the enzymes pyruvate kinase and lactate dehydrogenase21,22, or an assay measuring release of inorganic phosphate after reaction of the acetyl phosphate product with hydroxylamine23. Activity in the opposite, acetate-forming direction is measured by coupling ATP formation from ADP to the reduction of NADP+ to NADPH by the enzymes hexokinase and glucose 6-phosphate dehydrogenase24. Here we describe a method for the detection of acetate kinase activity in the direction of acetate formation that does not require coupling enzymes, but is instead based on direct determination of acetyl phosphate consumption. After the enzymatic reaction, remaining acetyl phosphate is converted to a ferric hydroxamate complex that can be measured spectrophotometrically, as for the hydroxamate assay. Thus, unlike the standard coupled assay for this direction that is dependent on the production of ATP from ADP, this direct assay can be used for acetate kinases that produce ATP or PPi.

Fowler, Matthew L.; Ingram-Smith, Cheryl J.; Smith, Kerry S.

2011-01-01

427

Direct detection of the acetate-forming activity of the enzyme acetate kinase.  

PubMed

Acetate kinase, a member of the acetate and sugar kinase-Hsp70-actin (ASKHA) enzyme superfamily, is responsible for the reversible phosphorylation of acetate to acetyl phosphate utilizing ATP as a substrate. Acetate kinases are ubiquitous in the Bacteria, found in one genus of Archaea, and are also present in microbes of the Eukarya. The most well characterized acetate kinase is that from the methane-producing archaeon Methanosarcina thermophila. An acetate kinase which can only utilize PP(i) but not ATP in the acetyl phosphate-forming direction has been isolated from Entamoeba histolytica, the causative agent of amoebic dysentery, and has thus far only been found in this genus. In the direction of acetyl phosphate formation, acetate kinase activity is typically measured using the hydroxamate assay, first described by Lipmann, a coupled assay in which conversion of ATP to ADP is coupled to oxidation of NADH to NAD(+) by the enzymes pyruvate kinase and lactate dehydrogenase, or an assay measuring release of inorganic phosphate after reaction of the acetyl phosphate product with hydroxylamine. Activity in the opposite, acetate-forming direction is measured by coupling ATP formation from ADP to the reduction of NADP(+) to NADPH by the enzymes hexokinase and glucose 6-phosphate dehydrogenase. Here we describe a method for the detection of acetate kinase activity in the direction of acetate formation that does not require coupling enzymes, but is instead based on direct determination of acetyl phosphate consumption. After the enzymatic reaction, remaining acetyl phosphate is converted to a ferric hydroxamate complex that can be measured spectrophotometrically, as for the hydroxamate assay. Thus, unlike the standard coupled assay for this direction that is dependent on the production of ATP from ADP, this direct assay can be used for acetate kinases that produce ATP or PP(i). PMID:22214984

Fowler, Matthew L; Ingram-Smith, Cheryl J; Smith, Kerry S

2011-01-01

428

Coupling supported lipid bilayer electrophoresis with matrix-assisted laser desorption/ionization-mass spectrometry imaging.  

PubMed

Herein, we describe a new analytical platform utilizing advances in heterogeneous supported lipid bilayer (SLB) electrophoresis and matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) imaging. This platform allowed for the separation and visualization of both charged and neutral lipid membrane components without the need for extrinsic labels. A heterogeneous SLB was created using vesicles containing monosialoganglioside GM1, disialoganglioside GD1b, POPC, as well as the ortho and para isomers of Texas Red-DHPE. These components were then separated electrophoretically into five resolved bands. This represents the most complex separation by SLB electrophoresis performed to date. The SLB samples were flash frozen in liquid ethane and dried under vacuum before imaging with MALDI-MS. Fluorescence microscopy was employed to confirm the position of the Texas Red labeled lipids, which agreed well with the MALDI-MS imaging results. These results clearly demonstrate this platform's ability to isolate and identify nonlabeled membrane components within an SLB. PMID:23731179

Pace, Hudson P; Sherrod, Stacy D; Monson, Christopher F; Russell, David H; Cremer, Paul S

2013-06-18

429

Western blotting of basic proteins after nondenaturing electrophoresis in acid conditions using the PhastSystem.  

PubMed

Electroblotting of basic proteins was performed from minigels after electrophoresis, under nondenaturing acidic conditions, by using the automated PhastSystem. Depending on the molecular masses of the proteins to be studied, various precast gel media were chosen. The transfer membranes with various types (nitrocellulose and polyvinylidene difluoride) and pore sizes (0.45 and 0.2 micron) were chosen accordingly. For the semidry electric transfer, a simple, discontinuous two-buffer system was used. The anode solution contained 0.3 M Tris, pH 10.4, and the cathode solution, 40 mM 6-amino-n-hexanoic acid, pH 7.6, with 20% v/v methanol each. The addition of 0.1% sodium dodecyl sulfate (SDS) in the cathode solution facilitated the elution of proteins from the gels and directed the migration of the negative SDS-protein complexes towards the anode membranes. The transfer conditions following native polyacrylamide gel electrophoresis allowed the visualization of basic proteins, with molecular weights ranging from 29,000 to 5,000, for which isoforms could be resolved and which retained their biological properties. PMID:8223396

Davril, M; Ducourouble, M P; Van-Seuningen, I

1993-09-01

430

Nanofiltration of rhodium tris(triphenylphosphine) catalyst in ethyl acetate solution  

NASA Astrophysics Data System (ADS)

Solvent resistant nanofiltration (SRNF) using polymer membranes has recently received enhanced attention due to the search for cleaner and more energy-efficient technologies. The large size of the rhodium tris(triphenylphosphine) [HRh(CO)(PPh3)3] catalyst (>400 Da) - relative to other components of the hydroformylation reaction provides the opportunity for a membrane separation based on retention of the catalyst species while permeating the solvent. The compatibility of the solvent-polyimide membrane (DuraMem{trade mark, serif} 200 and DuraMem{trade mark, serif} 500) combinations was assessed in terms of the membrane stability in solvent plus non-zero solvent flux at 2.0 MPa. Good HRh(CO)(PPh3)3 rejection (>0.95) and solvent fluxes of 9.9 L/m2.h1 at 2.0 MPa were obtained in the catalyst-ethyl acetate-DuraMem 500 system. The effect of pressure and catalyst concentration on the solvent flux and catalyst rejection was conducted on the catalyst-ethyl acetate-membrane systems. Increasing pressure substantially improved both solvent flux and catalyst rejection, while increasing catalyst concentration was found to be beneficial in terms of substantial increases in catalyst rejection without significantly affecting solvent flux.

Shaharun, Maizatul S.; Mustafa, Ahmad K.; Taha, Mohd F.

2012-09-01

431

Friction and wear behaviour of acetal and nylon gears  

Microsoft Academic Search

The current paper will present an extensive investigation of polymer gear (acetal and nylon) friction and wear behaviour. First, a unique test method for polymer gear wear will be described in brief and later used in the extensive investigation of acetal and nylon gear wear. Initial tests were performed using acetal pinions with acetal gears, and nylon pinions with nylon

K. Mao; W. Li; C. J. Hooke; D. Walton

2009-01-01

432

Modification of gel architecture and TBE/TAE buffer composition to minimize heating during agarose gel electrophoresis.  

PubMed

Agarose gel electrophoresis of DNA and RNA is routinely performed using buffers containing either Tris, acetate, and EDTA (TAE) or Tris, borate, and EDTA (TBE). Gels are run at a low, constant voltage (?10 V/cm) to minimize current and asymmetric heating effects, which can induce band artifacts and poor resolution. In this study, alterations of gel structure and conductive media composition were analyzed to identify factors causing higher electrical currents during horizontal slab gel electrophoresis. Current was reduced when thinner gels and smaller chamber buffer volumes were used, but was not influenced by agarose concentration or the presence of ethidium bromide. Current was strongly dependent on the amount and type of EDTA used and on the concentrations of the major acid-base components of each buffer. Interestingly, resolution and the mobilities of circular versus linear plasmid DNAs were also affected by the chemical form and amount of EDTA. With appropriate modifications to gel structure and buffer constituents, electrophoresis could be performed at high voltages (20-25 V/cm), reducing run times by up to 3-fold. The most striking improvements were observed with small DNAs and RNAs (10-100 bp): high voltages and short run times produced sharper bands and higher resolution. PMID:24637158

Sanderson, Brian A; Araki, Naoko; Lilley, Jennifer L; Guerrero, Gilberto; Lewis, L Kevin

2014-06-01

433

Membrane extraction for detoxification of biomass hydrolysates.  

PubMed

Membrane extraction was used for the removal of sulfuric acid, acetic acid, 5-hydroxymethyl furfural and furfural from corn stover hydrolyzed with dilute sulfuric acid. Microporous polypropylene hollow fiber membranes were used. The organic extractant consisted of 15% Alamine 336 in: octanol, a 50:50 mixture of oleyl alcohol:octanol or oleyl alcohol. Rapid removal of sulfuric acid, 5-hydroxymethyl and furfural was observed. The rate of acetic acid removal decreased as the pH of the hydrolysate increased. Regeneration of the organic extractant was achieved by back extraction into an aqueous phase containing NaOH and ethanol. A cleaning protocol consisting of flushing the hydrolysate compartment with NaOH and the organic phase compartment with pure organic phase enabled regeneration and reuse of the module. Ethanol yields from hydrolysates detoxified by membrane extraction using 15% Alamine 336 in oleyl alcohol were about 10% higher than those from hydrolysates detoxified using ammonium hydroxide treatment. PMID:22361069

Grzenia, David L; Schell, Daniel J; Wickramasinghe, S Ranil

2012-05-01

434

Nearest neighbor analysis of outer membrane proteins of nontypeable Haemophilus influenzae.  

PubMed Central

The arrangement of outer membrane proteins on the surface of nontypeable Haemophilus influenzae was investigated with cleavable and noncleavable bis-imidate cross-linking agents. Whole organisms were subjected to cross-linking agents, and oligomers of proteins were detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, two-dimensional gel electrophoresis, and immunoblot assay, using monoclonal antibodies to outer membrane proteins. The major outer membrane protein (P2) formed dimers and trimers detected by all three methods. Oligomers of other outer membrane proteins were not detected. These data indicate that P2 exists as a trimer on the outer membrane and suggest that other outer membrane proteins exist as monomers on the outer membrane. Images

Klingman, K L; Jansen, E M; Murphy, T F

1988-01-01

435

Removal of bisphenol A (BPA) from water by various nanofiltration (NF) and reverse osmosis (RO) membranes.  

PubMed

The removal of an endocrine disrupting compound, bisphenol A (BPA), from model solutions by selected nanofiltration (NF) and reverse osmosis (RO) membranes was studied. The commercially available membranes NF 90, NF 270, XLE BWRO, BW 30 (Dow FilmTech), CE BWRO and AD SWRO (GE Osmonics) were used to compare their performances for BPA removal. The water permeability coefficients, rejection of BPA and permeate flux values were calculated for all membranes used. No significant changes in their BPA removal were observed for all tight polyamide based NF and RO membranes tested except for loose NF 270 membrane. The polyamide based membranes exhibited much better performance than cellulose acetate membrane for BPA removal. Almost a complete rejection (? 98%) for BPA was obtained with three polyamide based RO membranes (BW 30, XLE BWRO and AD SWRO). But cellulose acetate based CE BWRO membrane offered a low and variable (10-40%) rejection for BPA. PMID:23731784

Yüksel, Suna; Kabay, Nalan; Yüksel, Mithat

2013-12-15

436

Calcination of calcium acetate and calcium magnesium acetate: effect of the reacting atmosphere  

Microsoft Academic Search

The calcination process of the calcium acetate (CA) and calcium magnesium acetate (CMA) was investigated as a previous step for coal gas desulfurisation during sorbent injection at high temperatures because the excellent results demonstrated by these sorbents as sulfur removal agents both in combustion and gasification processes. As pore structure developed during calcination is one of the most important characteristic

J. Adánez; L. F. de Diego; F. Garc??a-Labiano

1999-01-01

437

Correlation of vapor - liquid equilibrium data for acetic acid - isopropanol - water - isopropyl acetate mixtures  

Microsoft Academic Search

A correlation procedure for the prediction of vapor - liquid equilibrium of acetic acid - isopropanol - water - isopropyl acetate mixtures has been developed. It is based on the NRTL model for predicting liquid activity coefficients, and on the Hayden-O'Connell second virial coefficients for predicting the vapor phase of systems containing association components. When compared with experimental data the

E. A. Campanella

2006-01-01

438

Tested Demonstrations: Buffer Capacity of Various Acetic Acid-Sodium Acetate Systems: A Lecture Experiment.  

ERIC Educational Resources Information Center

Background information and procedures are provided for a lecture experiment which uses indicators to illustrate the concept of differing buffer capacities by titrating acetic acid/sodium acetate buffers with 1.0 molar hydrochloric acid and 1.0 molar sodium hydroxide. A table with data used to plot the titration curve is included. (JN)

Donahue, Craig J.; Panek, Mary G.

1985-01-01

439

Relaxometry, luminescence measurements, electrophoresis, and animal biodistribution of lanthanide(III) complexes of some polyaza macrocyclic acetates containing pyridine  

SciTech Connect

Four Gd{sup 3+} complexes [Gd(BP2A){sup +}, Gd(PC2A){sup +}, Gd(PCTA){sup 0}, and Gd(BPO4A){sup {minus}}] with polyazamacrocyclic ligands that contain a pyridine moiety were prepared and examined for possible use as MRI contrast enhancement agents. The authors estimated the number of inner sphere water molecules (q{sub Gd}) for the Gd{sup 3+} complexes from the values of q found for the Tb{sup 3+} and/or Eu{sup 3+} complexes by luminescence lifetime measurements. It was estimated that q{sub Gd} = 3.5, 3.3, 2.4, and 0.2 for Gd(BP2A){sup +}, Gd(PC2A){sup +}, Gd(PCTA){sup 0}, and Gd(BPO4A){sup {minus}}, respectively. The inner sphere relaxivities (r{sub 1,inner}) of these tetraaza macrocyclic complexes were higher than that of Gd(DOTA){sup {minus}} [i.e. 6.79 for Gd(BP2A){sup +}, 6.21 for Gd(PC2A){sup +}, and 4.60 for Gd(PCTA){sup 0} mM{sup {minus}1}s{sup {minus}1} at 40 MHz and 25{degrees}C], but the normalized relaxivities per q{sub Gd} (1.94, 1.88, and 1.92 mM{sup {minus}1}s{sup {minus}1}, respectively) were comparable to that of Gd(DOTA){sup {minus}}. A quantitative treatment of the NMRD profiles based on Solomon-Bloembergen-Morgan theory, using the NMRD profile of Gd(BPO4A){sup {minus}} to correct for an outer sphere contribution, showed that the complexes exhibit characteristics similar to that of Gd(DOTA){sup {minus}} but with shorter electronic relaxation times. Tissue biodistribution results using radioactive {sup 153}Sm and {sup 159}Gd complexes in rats indicate that the cationic [{sup 153}Sm-(BP2A){sup +} and {sup 153}Sm(PC2A){sup +}] complexes accumulate preferably in the bone tissue while the neutral [{sup 153}Sm-(PCTA){sup 0}] and anionic [{sup 153}Sm(BPO4A){sup {minus}}] complexes appear to have renal clearances similar to those of other low molecular weight contrast agents [i.e. Gd(DTPA){sup 2{minus}} and Gd(DOTA){sup {minus}}].

Kim, W.D.; Sherry, A.D. [Univ. of Texas, Dallas, Richardson, TX (United States); Kiefer, G.E.; McMillan, K. [Dow Chemical Co., Freeport, TX (United States); Maton, F.; Muller, R.N. [Univ. of Mons-Hainault (Belgium)

1995-04-12

440

Genera and species in acetic acid bacteria.  

PubMed

Taxonomic studies of acetic acid bacteria were historically surveyed. The genus Acetobacter was first introduced in 1898 with a single species, Acetobacter aceti. The genus Gluconobacter was proposed in 1935 for strains with intense oxidation of glucose to gluconic acid rather than oxidation of ethanol to acetic acid and no oxidation of acetate. The genus "Acetomonas" was described in 1954 for strains with polar flagellation and no oxidation of acetate. The proposals of the two generic names were due to confusion, and "Acetomonas" was a junior subjective synonym of Gluconobacter. The genus Acetobacter was in 1984 divided into two subgenera, Acetobacter and Gluconoacetobacter. The latter was elevated to the genus Gluconacetobacter in 1998. In the acetic acid bacteria, ten genera are presently recognized and accommodated to the family Acetobacteraceae, the Alphaproteobacteria: Acetobacteer, Gluconobacter, Acidomonas, Gluconacetobacter, Asaia, Kozakia, Swaminathania, Saccharibacter, Neoasaia and Granulibacter. In contrast, the genus Frateuria, strains of which were once named 'pseudacetic acid bacteria', was classified into the Gammaproteobacteria. The genus Gluconacetobacter was phylogenetically divided into two groups: the Gluconacetobacter liquefaciens group and the Gluconacetobacter xylinus group. The two groups were discussed taxonomically. PMID:18199517

Yamada, Yuzo; Yukphan, Pattaraporn

2008-06-30

441

Acetate reduces microglia inflammatory signaling in vitro  

PubMed Central

Acetate supplementation increases brain acetyl-CoA and histone acetylation and reduces lipopolysaccharide (LPS)-induced neuroglial activation and interleukin (IL)-1? expression in vivo. To determine how acetate imparts these properties, we tested the hypothesis that acetate metabolism reduces inflammatory signaling in microglia. To test this, we measured the effect acetate treatment had on cytokine expression, mitogen-activated protein kinase (MAPK) signaling, histone H3 at lysine 9 acetylation, and alterations of nuclear factor-kappa B (NF-?B) in primary and BV-2 cultured microglia. We found that treatment induced H3K9 hyperacetylation and reversed LPS-induced H3K9 hypoacetylation similar to that found in vivo. LPS also increased IL-1?, IL-6 and tumor necrosis factor-alpha (TNF-?) mRNA and protein, while treatment returned the protein to control levels and only partially attenuated IL-6 mRNA. In contrast, treatment increased mRNA levels of transforming-growth factor-?1 (TGF-?1) and both IL-4 mRNA and protein. LPS increased p38 MAPK and JNK phosphorylation at 4 and 2–4 hr respectively, while treatment reduced p38 MAPK and JNK phosphorylation only at 2 hr. In addition, treatment reversed the LPS-induced elevation of NF-?B p65 protein and phosphorylation at serine 468 and induced acetylation at lysine 310. These data suggest that acetate metabolism reduces inflammatory signaling and alters histone and non-histone protein acetylation.

Soliman, Mahmoud L.; Puig, Kendra L.; Combs, Colin K.; Rosenberger, Thad A.

2012-01-01

442

Atmospheric oxidation pathways of acetic acid.  

PubMed

One of the most abundant carboxylic acids measured in the atmosphere is acetic acid (CH(3)C(O)OH), present in rural, urban, and remote marine environments in the low-ppb range. Acetic acid concentrations are not well reproduced in global 3-D atmospheric models because of the poor inventory of sources and sinks to model its global distribution. To understand the complete oxidation of acetic acid in the atmosphere initiated by OH radicals, ab initio calculations are performed to describe in detail the energetics of the reaction potential energy surface (PES). The proposed reaction mechanism suggests that the CH(3)C(O)OH + OH reaction takes place via three pathways: the addition of OH to the central carbon, the abstraction of a methyl hydrogen, and the abstraction of an acidic hydrogen. The PES is characterized by prereactive H-complexes, transition states, and more interestingly unique radical-mediated isomerization reactions. From the analysis of the energetics, acetic acid atmospheric oxidation will proceed mainly via the abstraction of the acidic hydrogen, consistent with previous experimental and theoretical studies. The major byproducts from each pathway are identified. Glyoxylic acid is suggested to be a major byproduct of the atmospheric oxidation of acetic acid. The atmospheric fate of glyoxylic acid is discussed. PMID:16571046

Rosado-Reyes, Claudette M; Francisco, Joseph S

2006-04-01

443

Immunoproteome analysis of soluble and membrane proteins of Shigella fl exneri 2457T  

Microsoft Academic Search

AIM: To profi le the immunogenic proteins of Shigella flexneri (S. flexneri ) expressed during human infection using a proteomic approach. METHODS: Soluble and membrane protein extractions of S. fl exneri 2457T were separated by two-dimensional gel electrophoresis (2-DE). Proteins were transferred to PVDF membrane and immunoblotted with sera from shigellosis patients. Reactive protein spots were matched to Coomassie stained

Amy V Jennison; Rubhana Raqib; Naresh K Verm

2006-01-01

444

Permeability of cellophane membranes to parotid during dialysis.  

PubMed

Pooled paratoid saliva was dialyzed in cellophane membranes against water for periods of up to 1 week and loss of proteins was monitored by acrylamide gel-electrophoresis. A gradual loss of cationic proteins was observed whereas anionic proteins were not appreciably affected. Loss of the cationic proteins could be greatly reduced by performing dialyses against dilute electrolyte solutions rather than water. These effects were attributed primarily to electrostatic changes associated with the dialysis membranes. PMID:421819

Lamberts, B L; Meyer, T S

1979-02-15

445

Butyl acetate and yeasts interact in adhesion and germination of Botrytis cinerea conidia in vitro and in fungal decay of golden delicious apple.  

PubMed

Butyl acetate is a volatile aroma and flavor compound in apple. Conidia of three strains of Botrytis cinerea, a fungus that causes decay of apple fruit in postharvest storage, had greater adhesion to and greater germination on polycarbonate membrane filters on water inside sealed 500 cc glass jars that were injected with 4 microliters butyl acetate than conidia not so exposed. Conidial germination was highly correlated with conidial adhesion. The yeasts Sporobolomyces roseus and Cryptococcus laurentii, but not Saccharomyces cerevisiae, reduced the adhesion and germination promoting effect of butyl acetate. Conidia did not readily utilize butyl acetate as a food source, as shown by lack of tetrazolium violet reduction, whereas S. roseus and C. laurentii, but not S. cerevisiae did. Butyl acetate added to suspensions of conidia increased the electrical conductivity of the suspensions and increased the loss of 14C from 14C-labeled conidia compared to conidia unexposed to butyl acetate. Uptake of [14C]glucose by conidia was not increased by butyl acetate. Wounds of Golden Delicious apples inoculated with conidia (strain F-J-4) in a dilute solution of butyl acetate had greater decay than unexposed wounds. S. roseus and C. laurentii, but not S. cerevisiae, added with the conidia decreased the incidence or size of decay. Results indicated that butyl acetate increased conidial adhesion, stimulating conidial germination, and some yeasts can reduce this effect. PMID:11446303

Filonow, A B

2001-04-01

446

Recovering/concentrating of hemicellulosic sugars and acetic acid by nanofiltration and reverse osmosis from prehydrolysis liquor of kraft based hardwood dissolving pulp process.  

PubMed

This work investigated the feasibility of recovering and concentrating sugars and acetic acid (HAc) from prehydrolysis liquor (PHL) of the kraft-based dissolving pulp process prior to fermentation of hemicellulosic sugars, by the combination of activated carbon adsorption, nanofiltration (NF) and reverse osmosis (RO) processes. To reduce the fouling PHL was subjected to adsorption on activated carbon, then the treated PHL (TPHL) passed through a nanofiltration (NF DK) membrane to retain the sugars, and the permeate of acetic acid rich solution was passed through a reverse osmosis membrane (RO SG). It was found that for NF process sugars were concentrated from 48 to 227g/L at a volume reduction factor (VRF) of 5 while 80 to 90% of acetic acid was permeated. For the reverse osmosis process, 68% of acetic acid retention was achieved at pH 4.3 and 500 psi pressure and the HAc concentration increased from 10 to 50g/L. PMID:24434701

Ahsan, Laboni; Jahan, M Sarwar; Ni, Yonghao

2014-03-01

447

Cytenamide trifluoro-acetic acid solvate  

PubMed Central

Cytenamide forms a 1:1 solvate with trifluoro­acetic acid (systematic name: 5H-dibenzo[a,d]cyclo­hepta­triene-5-carboxamide trifluoro­acetic acid solvate), C16H13NO·C2HF3O2. The compound crystallizes with one mol­ecule of cytenamide and one of trifluoro­acetic acid in the asymmetric unit; these are linked by O—H?O and N—H?O hydrogen bonds to form an R 2 2(8) motif. The trifluoro­methyl group of the solvent mol­ecule displays rotational disorder over two sites, with site-occupancy factors of 0.964?(4) and 0.036?(4).

Johnston, Andrea; Florence, Alastair J.; Fabbiani, Francesca J. A.; Shankland, Kenneth; Bedford, Colin T.; Bardin, Julie

2008-01-01

448

Dynamic Protonation Equilibrium of Solvated Acetic Acid  

SciTech Connect

For the first time, the dynamic protonation equilibrium between an amino acid side chain analogue and bulk water as well as the diffusion properties of the excess proton were successfully reproduced through unbiased computer simulations. During a 50 ns Q-HOP MD simulation, two different regimes of proton transfer were observed. Extended phases of frequent proton swapping between acetic acid and nearby water were separated by phases where the proton freely diffuses in the simulation box until it is captured again by acetic acid. The pKa of acetic acid was calculated around 3.0 based on the relative population of protonated and deprotonated states and the diffusion coefficient of excess proton was computed from the average mean squared displacement in the simulation. Both calculated values agree well with the experimental measurements.

Gu, Wei; Frigato, Tomaso; Straatsma, TP; Helms, Volkhard H.

2007-04-13

449

The physicochemical property characterization of agar acetate.  

PubMed

A series of agar acetates with different degree of substitution (DS) were prepared, and their properties were determined and analyzed. The results showed that the gelling temperature, the gel melting temperature, the gel strength, the gel hardness, the gel fracturability, the gel springiness and the solution apparent viscosity of agar acetates all decreased except that their gel cohesiveness increased with the increase of DS. The variation process of agar molecules in solution from coil to helix could be also observed by measuring solution optical rotation in a lower concentration at which even the solution could not form a gel. The gel skeleton structures of agar acetates were of porous network structures, and the pores became smaller and denser with the increase of DS. After acetylation, the water holding capacity of the agar was improved, but its thermal stability was lowered. PMID:24906725

Xia, Kai; Liu, Xin; Zhao, Jingkun; Zhang, Xiaodong

2014-09-22

450

Outer membrane vesicles as acellular vaccine against pertussis  

Microsoft Academic Search

In this study the development and evaluation of outer membrane vesicles (OMVs) obtained from Bordetella pertussis as vaccines against pertussis disease is described. SDS-PAGE, immunoblot techniques and gel electrophoresis associated to tandem mass spectrometry were used to describe the composition of the OMVs obtained from B. pertussis Tohama CIP 8132 strain. These techniques revealed the presence of the main well-known

Roy Roberts; Griselda Moreno; Daniela Bottero; Maria Emilia Gaillard; Matías Fingermann; Augusto Graieb; Martin Rumbo; Daniela Hozbor

2008-01-01

451

Investigations of the Inhibitory Effects of Tocopherol (Vitamin E) on Free Radical Deterioration of Cellular Membranes.  

National Technical Information Service (NTIS)

The inhibitory effects are investigated of d,1-alpha-tocopherol and d,1-alpha-tocopheryl acetate on the free radical deterioration of cellular membranes. The level of toxicity of d,1-alpha-tocopherol and d,1-alpha-tocopheryl acetate in mice is determined....

D. Richardson

1975-01-01

452

Investigations of the inhibitory effects of tocopherol (vitamin E) on free radical deterioration of cellular membranes  

NASA Technical Reports Server (NTRS)

The inhibitory effects are investigated of d,1-alpha-tocopherol and d,1-alpha-tocopheryl acetate on the free radical deterioration of cellular membranes. The level of toxicity of d,1-alpha-tocopherol and d,1-alpha-tocopheryl acetate in mice is determined.

Richardson, D.

1975-01-01