Sample records for capillary electrophoretic study

  1. Capillary electrophoretic study on UDP-sugars in cells

    Institute of Scientific and Technical Information of China (English)


    Glucose is an important regulator of cell growth and metabolism. Uridine diphosphate sugars (UDP-sugars), as the intermediate products of metabolism, play pivotal roles as precursors in the synthesis of complex carbohydrates and glycolipids as well as lectose. It is very important to study their metabolism in cells in clinical biochemistry. A capillary electrophoretic method has been developed for the analysis of UDP-sugars and nucleotides. By using an uncoated capillary (70cm×50 μm) and 20 mmol/L borax buffer (pH 9), 4 important UDP-sugars can be analyzed in 15 min at 22 kV with satisfactory precision and sensitivity. The developed method has been applied to analyze UDP-sugars concentrations in lymphocytes, fibroblasts and mesangial cells, and the results show it not only is much better than HPLC method, but also can be used to measure the energy charge of cells.

  2. Capillary electrophoretic study on UDP-sugars in cells

    Institute of Scientific and Technical Information of China (English)

    许国旺; R.Lehmann; 路鑫; H.M.Liebich; 张玉奎; 卢佩章


    Glucose is an important regulator of cell growth and metabolism. Uridine diphosphate sugars (UDP-sugars), as the intermediate products of metabolism, play pivotal roles as precursors in the synthesis of complex carbohydrates and glycolipids as well as lectose. It is very important to study their metabolism in cells in clinical biochemistry. A capillary electrophoretic method has been developed for the analysis of UDP-sugars and nucleotides. By using an uncoated capillary (70cm×50μm) and 20 mmol/L borax buffer (pH 9), 4 important UDP-sugars can be analyzed in 15 min at 22 kV with satisfactory precision and sensitivity. The developed method has been applied to analyze UDP-sugars concentrations in lymphocytes, fibroblasts and mesangial cells, and the results show it not only is much better than HPLC method, but also can be used to measure the energy charge of cells.

  3. Capillary electrophoretic study of green fluorescent hollow carbon nanoparticles. (United States)

    Liu, Lizhen; Feng, Feng; Hu, Qin; Paau, Man Chin; Liu, Yang; Chen, Zezhong; Bai, Yunfeng; Guo, Fangfang; Choi, Martin M F


    CE coupled with laser-induced fluorescence and UV absorption detections has been applied to study the complexity of as-synthesized green fluorescent hollow carbon nanoparticles (HC-NP) samples. The effects of pH, type, and concentration of the run buffer and SDS on the separation of HC-NP are studied in detail. It is observed that phosphate run buffer is more effective in separating the HC-NP and the optimal run buffer is found to be 30 mM phosphate and 10 mM SDS at pH 9.0. The CE separation of this HC-NP is based on the difference in size and electrophoretic mobility of HC-NP. Some selected HC-NP fractions are collected and further characterized by UV-visible absorption and photoluminescence (PL) spectroscopy, MS, and transmission electron microscopy. The fractionated HC-NP show profound differences in absorption, emission characteristics, and PL quantum yield that would have been otherwise misled by studying the complex mixture alone. It is anticipated that our CE methodology will open a new initiative on extensive studies of individual HC-NP species in the biomedical, catalysis, electronic, and optical device, energy storage, material, and sensing field.


    The electrophoretic behavior of bensulfuron Me, sulfometuron Me, nicosulfuron (Accent), chlorimuron Et, thifensulfuron Me (Harmony), metsulfuron Me, and chlorsulfuron was studied under capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography (MEKC) conditio...

  5. Study on the Interaction between Strychnine and Bovine Serum Albumin by Capillary Electrophoretic Frontal Analysis

    Institute of Scientific and Technical Information of China (English)


    The protein binding constant, binding sites of the Strychnos alkaloid-strychnine and bovine serum albumin (BSA) was determined by capillary electrophoretic frontal analysis (CE-FA)for the first time. The experiment was carried out in a polyacrylamide-coated fused silica capillary (48.4 cm×50 μm i.d., 38.1 cm effective length) with 20 mmol/L citrate/MES buffer (pH 6.0, ionic strength 0.17). The applied voltage was 12 kV and detection wavelength was set at 257nm. The plateau height of the peak was employed to determine the unbound concentration of drug in BSA equilibrated sample solution based on the external drug standard in the absence of protein. The present method provides a convenient, accurate technique for the early stage of drug screening.

  6. Capillary electrophoretic behavior of seven sulfonylureas. (United States)

    Matchett, W H; Winnik, W; Brumley, W C


    The electrophoretic behavior of seven sulfonylureas (bensulfuron methyl, sulfometuron methyl, nicosulfuron [accent], chlorimuron ethyl, thifensulfuron methyl [harmony], metsulfuron methyl, and chlorsulfuron) was studied under capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography (MEKC) conditions. Mixtures of these compounds were separated with very high efficiencies (2 x 10(5) theoretical plates) in a running buffer consisting of 3 parts acetate buffer (25 mM, pH 5.0) and 1 part acetonitrile. In this buffer system, acetonitrile was shown to be superior to methanol, acetone, and ethanol as a nonpolar additive, but any of these solvents can be used to reduce electroosmotic flow (EOF) and to obtain adequate separation. On-column detection limits at 214 nM were of the order of 80-100 fM. Micellar agents such as sodium dodecyl sulfate (SDS) and sodium cholate (but not monosialoganglioside-Gm1 or starburst dendrimer, generation 2.5) improved separation in phosphate and borate buffers. Implications of these results for the development of methods to detect these compounds on matrices of environmental origin are discussed. In particular, the instability of these compounds in methanol is noted and degradation products are detected using free zone CE. The methanolysis products of sulfometuron are tentatively identified by tandem MS (negative ion conditions) as 2-amino-4,6-dimethylpyrimidine and 2-carboxymethylbenz(N-carboxymethyl)sulfonamide.

  7. Capillary electrophoretic and mass spectrometric analysis of a polydisperse fluorosurfactant. (United States)

    Al-Jarah, Suhair Yousif; Sjödahl, Johan; Woldegiorgis, Andreas; Emmer, Asa


    A fluorosurfactant has been studied using capillary electrophoresis and mass spectrometry. The fluorosurfactant, FC134, can be used as a buffer additive in capillary electrophoresis in order to decrease wall adsorption of proteins and in micellar electrokinetic chromatography. However, it has been discovered that this fluorosurfactant is polydisperse, thus containing substances with different lengths and structures. In this work, the fluorosurfactant sample components were separated by capillary electrophoresis. An uncoated as well as a poly(vinyl alcohol)-coated capillary were used with running electrolytes containing methanol and acetic acid. Following the capillary electrophoretic separation, fractions were collected for further analysis by MALDI-MS. Non-fractionated samples were also analyzed both by MALDI-MS and by ESI-MS.

  8. Increasing conclusiveness of metabonomic studies by chem-informatic preprocessing of capillary electrophoretic data on urinary nucleoside profiles. (United States)

    Szymańska, E; Markuszewski, M J; Capron, X; van Nederkassel, A-M; Heyden, Y Vander; Markuszewski, M; Krajka, K; Kaliszan, R


    Nowadays, bioinformatics offers advanced tools and procedures of data mining aimed at finding consistent patterns or systematic relationships between variables. Numerous metabolites concentrations can readily be determined in a given biological system by high-throughput analytical methods. However, such row analytical data comprise noninformative components due to many disturbances normally occurring in analysis of biological samples. To eliminate those unwanted original analytical data components advanced chemometric data preprocessing methods might be of help. Here, such methods are applied to electrophoretic nucleoside profiles in urine samples of cancer patients and healthy volunteers. The electrophoretic nucleoside profiles were obtained under following conditions: 100 mM borate, 72.5 mM phosphate, 160 mM SDS, pH 6.7; 25 kV voltage, 30 degrees C temperature; untreated fused silica capillary 70 cm effective length, 50 microm I.D. Different most advanced preprocessing tools were applied for baseline correction, denoising and alignment of electrophoretic data. That approach was compared to standard procedure of electrophoretic peak integration. The best results of preprocessing were obtained after application of the so-called correlation optimized warping (COW) to align the data. The principal component analysis (PCA) of preprocessed data provides a clearly better consistency of the nucleoside electrophoretic profiles with health status of subjects than PCA of peak areas of original data (without preprocessing).

  9. Study of nucleic acid-ligand interactions by capillary electrophoretic techniques: A review. (United States)

    Neaga, I O; Bodoki, E; Hambye, S; Blankert, B; Oprean, R


    The understanding of nucleic acids-ligand (proteins, nucleic acids or various xenobiotics) interactions is of fundamental value, representing the basis of complex mechanisms that govern life. The development of improved therapeutic strategies, as well as the much expected breakthroughs in case of currently untreatable diseases often relies on the elucidation of such biomolecular interactions. Capillary electrophoresis (CE) is becoming an indispensable analytical tool in this field of study due to its high versatility, ease of method development, high separation efficiency, but most importantly due to its low sample and buffer volume requirements. Most often the availability of the compounds of interest is severely limited either by the complexity of the purification procedures or by the cost of their synthesis. Several reviews covering the investigation of protein-protein and protein-xenobiotics interactions by CE have been published in the recent literature; however none of them promotes the use of these techniques in the study of nucleic acid interactions. Therefore, various CE techniques applicable for such interaction studies are discussed in detail in the present review. The paper points out the particular features of these techniques with respect the estimation of the binding parameters, in analytical signal acquisition and data processing, as well as their current shortcomings and limitations.

  10. Capillary electrophoretic study of individual exocytotic events in single mast cells

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    Ho, Andrea Ming-Wei [Iowa State Univ., Ames, IA (United States)


    The peak profile of individual degranulation events from the on-column release of serotonin from single rat peritoneal mast cells (RPMCs) was monitored using capillary electrophoresis with laser-induced native fluorescence detection (CE-LINF). Serotonin, an important biogenic amine, is contained in granules (0.25 fL) within RPMCs and is extruded by a process termed exocytosis. The secretagogue, Polymyxin B sulfate, was used as the CE running buffer after injection of a single RPMC into the separation capillary to stimulate the release of the granules. Because the release process occurs on a ms time scale, monitoring individual exocytotic events is possible with the coupling of high-speed CE and LINF detection.

  11. Effective electrophoretic mobilities and charges of anti-VEGF proteins determined by capillary zone electrophoresis. (United States)

    Li, S Kevin; Liddell, Mark R; Wen, He


    Macromolecules such as therapeutic proteins currently serve an important role in the treatment of eye diseases such as wet age-related macular degeneration and diabetic retinopathy. Particularly, bevacizumab and ranibizumab have been shown to be effective in the treatment of these diseases. Iontophoresis can be employed to enhance ocular delivery of these macromolecules, but the lack of information on the properties of these macromolecules has hindered its development. The objectives of the present study were to determine the effective electrophoretic mobilities and charges of bevacizumab, ranibizumab, and model compound polystyrene sulfonate (PSS) using capillary zone electrophoresis. Salicylate, lidocaine, and bovine serum albumin (BSA), which have known electrophoretic mobilities in the literature, were also studied to validate the present technique. The hydrodynamic radii and diffusion coefficients of BSA, bevacizumab, ranibizumab, and PSS were measured by dynamic light scattering. The effective charges were calculated using the Einstein relation between diffusion coefficient and electrophoretic mobility and the Henry equation. The results show that bevacizumab and ranibizumab have low electrophoretic mobilities and are net negatively charged in phosphate buffered saline (PBS) of pH 7.4 and 0.16M ionic strength. PSS has high negative charge but the electrophoretic mobility in PBS is lower than that expected from the polymer structure. The present study demonstrated that capillary electrophoresis could be used to characterize the mobility and charge properties of drug candidates in the development of iontophoretic drug delivery.

  12. Bacterial surface layer proteins as a novel capillary coating material for capillary electrophoretic separations

    Energy Technology Data Exchange (ETDEWEB)

    Moreno-Gordaliza, Estefanía, E-mail: [Division of Analytical Biosciences, Leiden Academic Centre for Drug Research, Universiteit Leiden, Einsteinweg 55, 2300, RA, Leiden (Netherlands); Department of Analytical Chemistry, Faculty of Chemistry, Universidad Complutense de Madrid, Avda. Complutense s/n, 28040, Madrid (Spain); Stigter, Edwin C.A. [Division of Analytical Biosciences, Leiden Academic Centre for Drug Research, Universiteit Leiden, Einsteinweg 55, 2300, RA, Leiden (Netherlands); Department of Molecular Cancer Research, Universitair Medisch Centrum Utrecht, Wilhelmina Kinder Ziekenhuis, Lundlaan 6, 3584, EA Utrecht (Netherlands); Lindenburg, Petrus W.; Hankemeier, Thomas [Division of Analytical Biosciences, Leiden Academic Centre for Drug Research, Universiteit Leiden, Einsteinweg 55, 2300, RA, Leiden (Netherlands)


    A novel concept for stable coating in capillary electrophoresis, based on recrystallization of surface layer proteins on hydrophobized fused silica capillaries, was demonstrated. Surface layer protein A (SlpA) from Lactobacillus acidophilus bacteria was extracted, purified and used for coating pre-silanized glass substrates presenting different surface wettabilities (either hydrophobic or hydrophilic). Contact angle determination on SlpA-coated hydrophobic silica slides showed that the surfaces turned to hydrophilic after coating (53 ± 5°), due to a protein monolayer formation by protein-surface hydrophobic interactions. Visualization by atomic force microscopy demonstrated the presence of a SlpA layer on methylated silica slides displaying a surface roughness of 0.44 ± 0.02 nm. Additionally, a protein layer was visualized by fluorescence microscopy in methylated silica capillaries coated with SlpA and fluorescein isothiocyanate-labeled. The SlpA-coating showed an outstanding stability, even after treatment with 20 mM NaOH (pH 12.3). The electroosmotic flow in coated capillaries showed a partial suppression at pH 7.50 (3.8 ± 0.5 10{sup −9} m{sup 2} V{sup −1} s{sup −1}) when compared with unmodified fused silica (5.9 ± 0.1 10{sup −8} m{sup 2} V{sup −1} s{sup −1}). To demonstrate the potential of this novel coating, the SlpA-coated capillaries were applied for the first time for electrophoretic separation, and proved to be very suitable for the isotachophoretic separation of lipoproteins in human serum. The separations showed a high degree of repeatability (absolute migration times with 1.1–1.8% coefficient-of-variation (CV) within a day) and 2–3% CV inter-capillary reproducibility. The capillaries were stable for more than 100 runs at pH 9.40, and showed to be an exceptional alternative for challenging electrophoretic separations at long-term use. - Highlights: • New coating using recrystallized surface-layer proteins on

  13. Electrophoretic Focusing: An Alternative to Capillary Electrophoresis Project (United States)

    National Aeronautics and Space Administration — Electrophoretic focusing is a new separation method intended to achieve high resolution within very short sample residence times because one fraction is separated at...

  14. On-capillary sample cleanup method for the electrophoretic determination of carbohydrates in juice samples. (United States)

    Morales-Cid, Gabriel; Simonet, Bartolomé M; Cárdenas, Soledad; Valcárcel, Miguel


    On many occasions, sample treatment is a critical step in electrophoretic analysis. As an alternative to batch procedures, in this work, a new strategy is presented with a view to develop an on-capillary sample cleanup method. This strategy is based on the partial filling of the capillary with carboxylated single-walled carbon nanotube (c-SWNT). The nanoparticles retain interferences from the matrix allowing the determination and quantification of carbohydrates (viz glucose, maltose and fructose). The precision of the method for the analysis of real samples ranged from 5.3 to 6.4%. The proposed method was compared with a method based on a batch filtration of the juice sample through diatomaceous earth and further electrophoretic determination. This method was also validated in this work. The RSD for this other method ranged from 5.1 to 6%. The results obtained by both methods were statistically comparable demonstrating the accuracy of the proposed methods and their effectiveness. Electrophoretic separation of carbohydrates was achieved using 200 mM borate solution as a buffer at pH 9.5 and applying 15 kV. During separation, the capillary temperature was kept constant at 40 degrees C. For the on-capillary cleanup method, a solution containing 50 mg/L of c-SWNTs prepared in 300 mM borate solution at pH 9.5 was introduced for 60 s into the capillary just before sample introduction. For the electrophoretic analysis of samples cleaned in batch with diatomaceous earth, it is also recommended to introduce into the capillary, just before the sample, a 300 mM borate solution as it enhances the sensitivity and electrophoretic resolution.

  15. Capillary Electrophoretic Immunoassay with Laser-induced Fluorescence Detection for Interferon-gamma

    Institute of Scientific and Technical Information of China (English)

    Hua ZHANG; Hai Ming WEI; Wen Rui JIN


    Capillary electrophoretic immunoassay with laser-induced fluorescence detection for recombinant human interferon-gamma (IFN-γ) was established. The limits of detection for three forms of IFN-γare 6.9 ng/L, 5.7 ng/L and 5.0 ng/L, respectively.

  16. Development of a Capillary Zone Electrophoretic Method for the Rapid Separation and Detection of Hepatotoxic Microcystins

    Energy Technology Data Exchange (ETDEWEB)

    Li, Paul C.H.; Hu, Shen; Lam, Paul K.S


    Analysis of trace amounts of various hepatotoxic microcystins in marine and freshwater samples is very important since these toxins, especially microcystin-LR, have been demonstrated to have tumour-promoting activity. In this study, instead of measuring the total amount of microcystins, we developed a capillary zone electrophoretic method for the separation and detection of individual toxin standards. No additives were used for enhancement of resolution. This technique is characterized by a high separation efficiency, short analysis time and small sample volume. In order to improve the detection sensitivity, a laser-induced fluorescence detector was used, and the labelling of microcystins was accomplished through a two-step procedure. First, the microcystin standards were converted into cysteine conjugates, followed by derivatization with Fluorescein 5-Isothiocyanate (FITC). After derivatization, the FITC-labelled microcystins were directly injected, separated and detected in 8 min. This method was shown to be a promising technique for sensitive and rapid analysis of individual microcystin toxins.

  17. Correlation between Molecular Structures and Relative Electrophoretic Mobility in Capillary Electrophoresis: Alkylpyridines

    Institute of Scientific and Technical Information of China (English)

    YAO, Xiao-Jun; FAN, Bo-Tao; DOUCET, J. P.; PANAYE, A.; LIU, Man-Cang; ZHANG, Rui-Sheng; HU, Zhi-De


    The quantitative relationship between relative electrophoretic mobility in capillary electrophoresis for a series of 31 closely related alkylpyridines and their molecular structures was studied by using CODESSA. According to the t-test on the results, we found that the three most important descriptors affecting the mobility are the relative number of rings (NR), Min e-n attraction for a C-N bond (MEN) and average complementary information index (ACIC). With these structure descriptors a good three-parameter linear model was developed to correlate the mobility of these compounds with their structures. This model can not only correctly predict the migration behavior of these compounds, but also find the structural factors which are responsible for the migration behavior of these compounds,thus can help to explain the separation mechanism of these compounds. The method used in this work can also be extended to the mobility-structure relationship research of other compounds.

  18. Ligand-substitution mode capillary electrophoretic reactor: extending capillary electrophoretic reactor toward measurement of slow dissociation kinetics with a half-life of hours. (United States)

    Iki, Nobuhiko; Takahashi, Mariko; Takahashi, Toru; Hoshino, Hitoshi


    A method employing capillary electrophoresis (CE) was developed to determine the rate constant of the very slow spontaneous dissociation of a complex species. The method uses a CE reactor (CER) to electrophoretically separate components from a complex zone and, thus, spontaneously dissociate a complex. The dissociation is accelerated by ligand substitution (LS) involving a competing ligand added to the electrophoretic buffer. The LS-CER method is validated using the dissociation of a Ti(IV)-catechin complex and EDTA as a competing ligand. There is good agreement between the spontaneous dissociation rate constant (k(d) = (1.64 +/- 0.63) x 10(-4) s(-1)) and the rate constant obtained by a conventional batchwise LS reaction (k(d) = (1.43 +/- 0.04) x 10(-4) s(-1)). Furthermore, the usefulness of the method is demonstrated using a Ti(IV)-tiron complex, for which k(d) = (0.51 +/- 0.43) x 10(-4) s(-1), corresponding to a half-life (t(1/2)) of 3.8 h. Notably, a single run of LS-CER for the Ti(IV) complex is completed within 40 min, implying that LS-CER requires a considerably shorter measurement time (roughly equal to t(1/2)) than conventional CER. LS-CER can be widely applied to determine the spontaneous dissociation rates of inorganic diagnostic and therapeutic reagents as well as of biomolecular complexes.

  19. Use of gemini surfactants as semipermanent capillary coatings in aqueous-organic solvents for capillary electrophoretic separation of inorganic anions. (United States)

    Liu, Qian; Li, Yanqing; Yao, Lihua; Yao, Shouzhuo


    This paper proposes a new method for CE separation of inorganic anions based on the use of gemini surfactants as capillary coatings in mixed aqueous-organic solvents. The semipermanent gemini surfactant coatings were facilely prepared by rinsing the capillary with 18-s-18 solutions; they can keep be stable during the electrophoretic runs without surfactants in buffer. The coatings showed a good tolerance of methanol (MeOH) or ACN, e.g. at pH 8.0 and with 40% v/v MeOH or ACN, the EOF magnitude after 60 min of continuous electrokinetic rinsing only decreased by 2.9 or 6.0%, respectively. The coatings were successfully applied to the separation of inorganic anions. Adding organic solvents in buffer can effectively improve the resolution and efficiencies; however, it remarkably prolonged the analysis time due to the suppression of EOF. Interestingly, varying the spacer length of the gemini surfactants can also modulate (improve) the resolution but without any sacrifice of analysis time. This benefit was resulted from the unique chemical structures of gemini surfactants because it introduced a new variable, i.e. the spacer length, to the separation mechanism.

  20. Electrophoretic behavior of charge regulated zwitter ionic buffers in covalently and dynamically coated fused silica capillaries

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    Medhat A. Al-Ghobashy


    Full Text Available In this work, the electrophoretic behavior of zwitterionic buffers is investigated in the absence of electroosmotic flow (EOF. Electro mobilization of capillary contents is noted when zwitterionic buffers are employed as the background electrolyte at a pH where the buffering moiety carries a net charge. The bulk flow of capillary contents was demonstrated via monitoring the migration of a neutral marker as well as a free and micellar negatively charged marker and SDS–protein complexes. This electrolyte-driven mobilization (EDM was investigated in detail using 4-(2-hydroxyethylpiprazine-1-ethanesulfonic acid (HEPES buffer over a wide pH range (pH 4.0–8.0. Results confirmed that at a pH where HEPES molecules carry a net negative charge, a bulk flow toward the anode is observed. This was attributed to the migration of HEPES ions toward the anode along with their hydration shells. The relatively large difference in size and solvation number between the ionic buffering moiety and its counter-migrating ions (Na+ or H+ resulted in such a net movement. Results indicated that at constant voltage, plotting the measured current versus buffer pH can be used for determination of the isoelectric point of the zwitterionic buffering moiety. Furthermore, this novel mobilization modality was demonstrated using five different HEPES analogs over pH range 5.0–8.0. More in depth investigations are required in order to explore the applicability of EDM in coated capillaries of different wall chemistries and dimensions.



    Fitri, Noor; Thiele, Björn; Günther, Klaus; Buchari, Buchari


    A capillary electrophoretic (CE) analysis with ultra-violet (UV) detection was performed for further separation of low-molecular-mass (LMM) calcium species in phloem sap of Ricinus communis L. Two different background electrolytes (BGE) were used for the separation; these are (1) hydrogen phosphate/dihydrogen phosphate buffer containing cetyltrimethylammonium bromide (CTAB) as an electro-osmotic flow (EOF) modifier, and (2) boric acid buffer containing CTAB. Various parameters affecting the a...

  2. Capillary electrophoretic separation of humic substances using hydroxyethyl cellulose as a buffer additive and its application to characterization of humic substances in a river water sample. (United States)

    Takahashi, Toru; Kawana, Jun; Hoshino, Hitoshi


    We have developed a concise tool for the investigation of the transition of humic substances in environmental water. The separation of water-soluble humic substances was achieved rapidly and effectively by capillary electrophoresis using a polyacrylamide-coated capillary and a phosphate electrophoretic buffer solution (pH 7.0) containing hydroxyethyl cellulose. The separation mechanism was assessed using the ultrafiltration technique. The effect of the complexation of humic substances with metal ions was studied by using the proposed method. When Fe(III) ions or EDTA was added to the sample solution of fulvic acid, a distinct change in the electropherogram pattern based on the conformational change of fulvic acid was observed. The successful application of the proposed method to the characterization of humic substances in a river water sample was also demonstrated.

  3. Inter-instrumental method transfer of chiral capillary electrophoretic methods using robustness test information. (United States)

    De Cock, Bart; Borsuk, Agnieszka; Dejaegher, Bieke; Stiens, Johan; Mangelings, Debby; Vander Heyden, Yvan


    Capillary electrophoresis (CE) is an electrodriven separation technique that is often used for the separation of chiral molecules. Advantages of CE are its flexibility, low cost and efficiency. On the other hand, the precision and transfer of CE methods are well-known problems of the technique. Reasons for the more complicated method transfer are the more diverse instrumental differences, such as total capillary lengths and capillary cooling systems; and the higher response variability of CE methods compared to other techniques, such as liquid chromatography (HPLC). Therefore, a larger systematic change in peak resolutions, migration times and peak areas, with a loss of separation and efficiency may be seen when a CE method is transferred to another laboratory or another type of instrument. A swift and successful method transfer is required because development and routine use of analytical methods are usually not performed in the same laboratory and/or on the same type of equipment. The aim of our study was to develop transfer rules to facilitate CE method transfers between different laboratories and instruments. In our case study, three β-blockers were chirally separated and inter-instrumental transfers were performed. The first step of our study was to optimise the precision of the chiral CE method. Next, a robustness test was performed to identify the instrumental and experimental parameters that were most influencing the considered responses. The precision- and the robustness study results were used to adapt instrumental and/or method settings to improve the transfer between different instruments. Finally, the comparison of adapted and non-adapted transfers allowed deriving some rules to facilitate CE method transfers.

  4. Characterization of Dickeya and Pectobacterium species by capillary electrophoretic techniques and MALDI-TOF MS. (United States)

    Šalplachta, Jiří; Kubesová, Anna; Horký, Jaroslav; Matoušková, Hana; Tesařová, Marie; Horká, Marie


    Dickeya and Pectobacterium species represent an important group of broad-host-range phytopathogens responsible for blackleg and soft rot diseases on numerous plants including many economically important plants. Although these species are commonly detected using cultural, serological, and molecular methods, these methods are sometimes insufficient to classify the bacteria correctly. On that account, this study was undertaken to investigate the feasibility of three individual analytical techniques, capillary zone electrophoresis (CZE), capillary isoelectric focusing (CIEF), and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), for reliable classification of Dickeya and Pectobacterium species. Forty-three strains, representing different Dickeya and Pectobacterium species, namely Dickeya dianthicola, Dickeya dadantii, Dickeya dieffenbachiae, Dickeya chrysanthemi, Dickeya zeae, Dickeya paradisiaca, Dickeya solani, Pectobacterium carotovorum, and Pectobacterium atrosepticum, were selected for this purpose. Furthermore, the selected bacteria included one strain which could not be classified using traditional microbiological methods. Characterization of the bacteria was based on different pI values (CIEF), migration velocities (CZE), or specific mass fingerprints (MALDI-TOF MS) of intact cells. All the examined strains, including the undetermined bacterium, were characterized and classified correctly into respective species. MALDI-TOF MS provided the most reliable results in this respect.

  5. Analysis of urinary drugs of abuse by a multianalyte capillary electrophoretic immunoassay. (United States)

    Caslavska, J; Allemann, D; Thormann, W


    This paper characterizes a novel multianalyte competitive binding, electrokinetic capillary-based immunoassay for urinary methadone, opiates, benzoylecgonine (cocaine metabolite) and amphetamines. After incubation of 25 microliters urine with the reactants for several minutes in the presence of an internal standard, a small aliquot of the mixture is applied onto a fused-silica capillary and the unbound fluorescein labelled drug tracers are monitored by capillary electrophoresis with on-column laser induced fluorescence detection. The multianalyte assay is shown to be rapid, simple, quantitative, capable of recognizing urinary drug concentrations > or = 30 ng/ml and suitable for screening of patient urines. Data are demonstrated to compare well with those obtained by routine screening methods based on enzyme multiplied immunoassay techniques and fluorescence polarization immunoassays. The electrokinetic capillary assay has been validated via analysis of external quality control urines and confirmation analysis of patient urines using GC-MS.

  6. Capillary electrophoretic analysis of flavonoids in single-styled hawthorn (Crataegus monogyna Jacq.) ethanolic extracts. (United States)

    Urbonaviciūte, A; Jakstas, V; Kornysova, O; Janulis, V; Maruska, A


    Flavonoids are an important group of natural compounds, which can prevent coronary heart disease and have antioxidant properties. Hawthorn is a well known and widely used medicinal plant due to its cardiotonic activity. Previous studies refer mostly to the HPLC analysis of the flavonoids: vitexin, quercetin, hyperoside, oligomeric procyanidins, which appear to be primarily responsible for the cardiac action of the plant. Aqueous ethanolic extracts of single-styled hawthorn (Crataegus monogyna Jacq., f.: Rosaceae Juss.) leaves and sprouts were analyzed by means of capillary zone electrophoresis (CZE). Influence of vegetation period on the extract qualitative composition and flavonoids quantities was evaluated. Sample preparation by extraction using different concentration of aqueous ethanol (40-96%, v/v) and the influence of extractant composition on the recovery of flavonoids are discussed in detail. The results obtained using CZE are compared to the results of spectrophotometric and HPLC analysis of the extracts. The effect of storage conditions of extracts (solar irradiation, temperature and duration) on degradation of flavonoids was investigated.

  7. Electrophoretic analysis of biomarkers using capillary modification with gold nanoparticles embedded in a polycation and boron doped diamond electrode. (United States)

    Zhou, Lin; Glennon, Jeremy D; Luong, John H T


    Field-amplified sample stacking using a fused silica capillary coated with gold nanoparticles (AuNPs) embedded in poly(diallyl dimethylammonium) chloride (PDDA) has been investigated for the electrophoretic separation of indoxyl sulfate, homovanillic acid (HVA), and vanillylmandelic acid (VMA). AuNPs (27 nm) exhibit ionic and hydrophobic interactions, as well as hydrogen bonding with the PDDA network to form a stable layer on the internal wall of the capillary. This approach reverses electro-osmotic flow allowing for fast migration of the analytes while retarding other endogenous compounds including ascorbic acid, uric acid, catecholamines, and indoleamines. Notably, the two closely related biomarkers of clinical significance, HVA and VMA, displayed differential interaction with PDDA-AuNPs which enabled the separation of this pair. The detection limit of the three analytes obtained by using a boron doped diamond electrode was approximately 75 nM, which was significantly below their normal physiological levels in biological fluids. This combined separation and detection scheme was applied to the direct analysis of these analytes and other interfering chemicals including uric and ascorbic acids in urine samples without off-line sample treatment or preconcentration.

  8. Rational use of stacking principles for signal enhancement in capillary electrophoretic separations of poliovirus samples. (United States)

    Oita, Iuliana; Halewyck, Hadewych; Pieters, Sigrid; Dejaegher, Bieke; Thys, Bert; Rombaut, Bart; Vander Heyden, Yvan


    The use of an earlier developed capillary electrophoresis (CE) method, either to investigate poliovirus (PV) samples with a low viral-purity level or to study the less abundant sub-viral particles, revealed the necessity for an intra-column signal enhancement strategy. Although intra-column signal enhancement is a very popular approach to assay small molecules, it is less straightforward for the analysis of biological macromolecules or particles. A reason could be that, for a proper signal enhancement approach, these samples have to be thoroughly studied to understand the factors affecting the separation process. For the investigated PV samples, a screening design revealed that injecting larger sample plugs significantly enhanced the analytical signal, but also significantly decreased the separation efficiency. A subsequently executed central composite design determined the largest sample plug that can be injected without compromising the separation. Finally, the sample dilution and the length of the injected plug were used for tuning the intensity of the analytical response. Two combinations of sample dilution and injected plug size, at extreme values, were investigated in detail to define the best procedure for PV analysis using CE. In both situations, PV was effectively separated and quantified in rather complex samples, showing a good repeatability, an acceptable linearity for the PV particles and a decreased limit of detection in comparison with the existing method. In conclusion, intra-column signal enhancement can be successfully applied for viral suspensions, extending the applicability of CE methods to samples with lower virus concentrations, and/or allowing a significant reduction in the minimum required volume of sample. For PV samples, 5μl of sample is necessary instead of the previous 20μl, while the analytical signal was enhanced up to 14 times. The results of this study can provide a basis for the development of routine CE methods for viral

  9. Capillary electrophoretic determination of main components of natural dyes with MS detection. (United States)

    Surowiec, Izabella; Pawelec, Katarzyna; Rezeli, Melinda; Kilar, Ferenc; Trojanowicz, Marek


    CE with UV-Vis and MS detections was investigated as a technique for detection of main components of selected natural dyes of plant and insect origin. The BGE giving the best separation of the investigated flavonoids and anthraquinoids, suitable for MS detection consisted of 40 mM ammonium acetate solution of pH 9.5 with 40% ACN. LODs obtained with MS detection were even one order of magnitude lower than the ones obtained with UV-Vis detection. Application of MS detection enabled determination of eleven dye compounds from three different chemical groups in 15 min. and proved to be more satisfactory than diode-array detection in the electrophoretic analysis of main classes of natural dyes both in terms of selectivity and sensitivity of analysis.

  10. Capillary electrophoresis, gas-phase electrophoretic mobility molecular analysis, and electron microscopy: effective tools for quality assessment and basic rhinovirus research. (United States)

    Weiss, Victor U; Subirats, Xavier; Kumar, Mohit; Harutyunyan, Shushan; Gösler, Irene; Kowalski, Heinrich; Blaas, Dieter


    We describe standard methods for propagation, purification, quality control, and physicochemical characterization of human rhinoviruses, using HRV-A2 as an example. Virus is propagated in HeLa-OHIO cells grown in suspension culture and purified via sucrose density gradient centrifugation. Purity and homogeneity of the preparations are assessed with SDS-polyacrylamide gel electrophoresis (SDS-PAGE), capillary electrophoresis (CE), gas-phase electrophoretic mobility molecular analysis (GEMMA), and electron microscopy (EM). We also briefly describe usage of these methods for the characterization of subviral particles as well as for the analysis of their complexes with antibodies and soluble recombinant receptor mimics.

  11. ESI-MS compatible permanent coating of glass surfaces using poly(ethylene glycol)-terminated alkoxysilanes for capillary zone electrophoretic protein separations. (United States)

    Razunguzwa, Trust T; Warrier, Manoj; Timperman, Aaron T


    Thin poly(ethylene glycol) silane (PEG-silane) coatings formed from N-(triethoxysilyl propyl)-O-poly(ethylene oxide) urethane with different chain lengths of poly(ethylene glycol) (MW 750 and 4000-5000) are used to modify glass microfluidic channels and fused-silica capillaries for electrophoretic separations of proteins. These coatings combine three important properties, which make them favorable for proteomic analyses including reduction of protein adsorption, compatibility with mass spectrometry due to their stability, and the ability to control the magnitude of electroosmotic flow (EOF). The coatings have been successfully used in microfluidic chips and fused-silica capillaries for separation of protein sample mixtures under low EOF conditions. The long-chain and mixed PEG-silane coatings suppress electroosmotic flow by more than 90%, whereas the short-chain PEG silane suppresses EOF by 65-75% at pH values of 3-9. The long-chain and mixed PEG-silane coatings are suitable for low EOF applications or for cases where negative effects of EOF are to be minimized. Efficient separations of unlabeled basic proteins at low pH and FITC-labeled proteins at high pH were achieved, as well as excellent stability for at least 200 electrophoretic runs. Additionally, these covalent coatings produce no detectable background ions in ESI-MS, making them compatible with on-line mass spectrometry.

  12. [Electrophoretic studies of serum protein fractions in horses with laminitis]. (United States)

    Edinger, H; Miller, I; Stanek, C; Gemeiner, M


    The spectrum of serum proteins was evaluated in 46 horses affected with spontaneous laminitis and correlations between the severity of the disease and changes of the protein pattern were analyzed. The investigation was made in two groups; group A consisted of 21 horses of various breeds (warmblood, thoroughbred, standardbred) and group B of 25 ponys. Each group was subdivided according to the severity of the disease, using the OBEL-grade (OG) classification system. Serum proteins were separated by different one- and two-dimensional electrophoretic methods. Sera analysed by cellulose acetate electrophoresis showed a significant difference in the alpha 1-globulin fraction between OG II and OG IV affected horses. An increasing severity of the disease was correlated with a decrease of the alpha 1-globulins. The other protein fractions didn't show a uniform tendency. In group B there was a significant difference in the alpha 1-globulin fractions of OG II and OG III and in the beta 2-globulin fractions of OG I and OG II affected ponys. The acute phase proteins C3c, C4, Hp and fibronectin could be determined in a preliminary study in horse serum using the cross-reactivity of antibodies against the homologous human proteins.

  13. Characterization of rhinovirus subviral A particles via capillary electrophoresis, electron microscopy and gas-phase electrophoretic mobility molecular analysis: Part I. (United States)

    Weiss, Victor U; Subirats, Xavier; Pickl-Herk, Angela; Bilek, Gerhard; Winkler, Wolfgang; Kumar, Mohit; Allmaier, Günter; Blaas, Dieter; Kenndler, Ernst


    During infection, enteroviruses, such as human rhinoviruses (HRVs), convert from the native, infective form with a sedimentation coefficient of 150S to empty subviral particles sedimenting at 80S (B particles). B particles lack viral capsid protein 4 (VP4) and the single-stranded RNA genome. On the way to this end stage, a metastable intermediate particle is observed in the cell early after infection. This subviral A particle still contains the RNA but lacks VP4 and sediments at 135S. Native (150S) HRV serotype 2 (HRV2) as well as its empty (80S) capsid have been well characterized by capillary electrophoresis. In the present paper, we demonstrate separation of at least two forms of subviral A particles on the midway between native virions and empty 80S capsids by CE. For one of these intermediates, we established a reproducible way for its preparation and characterized this particle in terms of its electrophoretic mobility and its appearance in transmission electron microscopy (TEM). Furthermore, the conversion of this intermediate to 80S particles was investigated. Gas-phase electrophoretic mobility molecular analysis (GEMMA) yielded additional insights into sample composition. More data on particle characterization including its protein composition and RNA content (for unambiguous identification of the detected intermediate as subviral A particle) will be presented in the second part of the publication.

  14. Use of beta-cyclodextrin in the capillary zone electrophoretic separation of the components of clandestine heroin preparations. (United States)

    Macchia, M; Manetto, G; Mori, C; Papi, C; Di Pietro, N; Salotti, V; Bortolotti, F; Tagliaro, F


    The present paper describes the methodological optimization and validation of a capillary zone electrophoresis method for the rapid determination of heroin, secondary products and additives present in clandestine heroin samples, by using 20 mM beta-cyclodextrins in phosphate buffer, pH 3.23. Applied potential was 15 kV and separation temperature was 24 degrees C; detection was by UV absorption at 200 nm wavelength. Heroin samples were first dissolved in CHCl3-MeOH (96:4, v/v) and injected by pressure (0.5 p.s.i., 3 s; 1 p.s.i.=6894.76 Pa) after evaporation of the organic mixture and reconstitution in aqueous buffer. Under the described conditions, phenylethylamine (internal standard), morphine, monoacetylmorphine, heroin, acetylcodeine, papaverine, codeine and narcotine were baseline resolved in less than 10 min. The limit of detection was better than 1 microg/ml for each analyte. The study of the intra-day and day-to-day precision showed, in terms of migration times, RSDs < or = 0.71% and, in terms of peak areas, RSDs < or = 3.2%. Also, the evaluation of linearity and analytical accuracy of the method provided good results for all the analytes investigated, thus allowing its application to real cases of seized controlled drug preparations.

  15. Screening for urinary amphetamine and analogs by capillary electrophoretic immunoassays and confirmation by capillary electrophoresis with on-column multiwavelength absorbance detection. (United States)

    Ramseier, A; Caslavska, J; Thormann, W


    This paper characterizes competitive binding, electrokinetic capillary-based immunoassays for screening of urinary amphetamine (A) and analogs using reagents which were commercialized for a fluorescence polarization immunoassay (FPIA). After incubation of 25 microL urine with the reactants, a small aliquot of the mixture is applied onto a fused-silica capillary and unbound fluorescein-labeled tracer compounds are monitored by capillary electrophoresis with on-column laser-induced fluorescence detection. Configurations in presence and absence of micelles were investigated and found to be capable of recognizing urinary D-(+)-amphetamine at concentrations > about 80 ng/mL. Similar responses were obtained for racemic methamphetamine (MA) and 3,4-methylenedioxymethamphetamine (MDMA). The electrokinetic immunoassay data suggest that the FPIA reagent kit includes two immunoassay systems (two antibodies and two tracer molecules), one that recognizes MA and MDMA, and one that is geared towards monitoring of A. For confirmation analysis of urinary amphetamines and ephedrines, capillary electrophoresis in a pH 9.2 buffer and multiwavelength UV detection was employed. The suitability of the electrokinetic methods for screening and confirmation is demonstrated via analysis of patient and external quality control urines.

  16. Classification of Spanish white wines using their electrophoretic profiles obtained by capillary zone electrophoresis with amperometric detection. (United States)

    Arribas, Alberto Sánchez; Martínez-Fernández, Marta; Moreno, Mónica; Bermejo, Esperanza; Zapardiel, Antonio; Chicharro, Manuel


    A method was developed for the simultaneous detection of eight polyphenols (t-resveratrol, (+)-catechin, quercetin and p-coumaric, caffeic, sinapic, ferulic, and gallic acids) by CZE with electrochemical detection. Separation of these polyphenols was achieved within 25 min using a 200 mM borate buffer (pH 9.4) containing 10% methanol as separation electrolyte. Amperometric detection of polyphenols was carried out with a glassy carbon electrode (GCE) modified with a multiwalled carbon nanotubes (CNT) layer obtained from a dispersion of CNT in polyethylenimine. The excellent electrochemical properties of this modified electrode allowed the detection and quantification of the selected polyphenols in white wines without any pretreatment step, showing remarkable signal stability despite the presence of potential fouling substances in wine. The electrophoretic profiles of white wines, obtained using this methodology, have proven to be useful for the classification of these wines by means of chemometric multivariate techniques. Principal component analysis and discriminant analysis allowed accurate classification of wine samples on the basis of their grape varietal (verdejo and airén) using the information contained in selected zones of the electropherogram. The utility of the proposed CZE methodology based on the electrochemical response of CNT-modified electrodes appears to be promising in the field of wine industry and it is expected to be successfully extended to classification of a wider range of wines made of other grape varietals.

  17. Capillary electrophoretic methods in the development of metal-based therapeutics and diagnostics: new methodology and applications. (United States)

    Bytzek, Anna K; Hartinger, Christian G


    In recent years, capillary electrophoresis (CE) has matured to a standard method in medicinal inorganic chemistry. More and more steps of the drug discovery process are followed by CE. However, not only the number of applications has steadily increased but also the variety of used methodology has significantly broadened and, as compared to a few years ago, a wider scope of separation modes and hyphenated systems has been used. Herein, a summary of the newly utilized CE methods and their applications in metallodrug research in the timeframe 2006-2011 is presented, following related reviews from 2003 and 2007 (Electrophoresis, 2003, 24, 2023-2037; Electrophoresis 2007, 28, 3436-3446). Areas covered include impurity profiling, quality control of pharmaceutical formulations, lipophilicity estimation, interactions between metallodrugs and proteins or nucleotides, and characterization and also quantification of metabolites in biological matrices and real-world samples.

  18. Characterization of rhinovirus subviral A particles via capillary electrophoresis, electron microscopy and gas phase electrophoretic mobility molecular analysis: part II. (United States)

    Subirats, Xavier; Weiss, Victor U; Gösler, Irene; Puls, Christoph; Limbeck, Andreas; Allmaier, Günter; Kenndler, Ernst


    Human rhinoviruses (HRVs) are valuable tools in the investigation of early viral infection steps due to their far reaching (although still incomplete) characterization. During endocytosis, native virions first loose one of the four capsid proteins (VP4); corresponding particles sediment at 135S and were termed subviral A particles. Subsequently, the viral RNA genome leaves the viral shell giving rise to empty capsids. In continuation of our previous work with HRV serotype 2 (HRV2) intermediate subviral particles, in which we were able to discriminate by CE even between two intermediates (AI and AII) of virus uncoating, we further concentrated on the characterization of AI particles with the electrophoretic mobility of around -17.2 × 10(-9) m(2) /Vs at 20°C. In the course of our present work we related these particles to virions as previously described at the subviral A stage of uncoating (and as such sedimenting at 135S) by determination of their protein and RNA content--in comparison to native virions AI particles did not include VP4, however, still 93% of their initial RNA content. Binding of an mAb specific for subviral particles demonstrated antigenic rearrangements on the capsid surface at the AI stage. Furthermore, we investigated possible factors stabilizing intermediates of virus uncoating. We could exclude the influence of the previously suspected so-called contaminant of virus preparation on HRV2 subviral particle formation. Instead, we regarded other factors being part of the virus preparation system and found a dependence of AI particle formation on the presence of divalent cations.

  19. Fabrication and kinetics study of nano-Al/NiO thermite film by electrophoretic deposition. (United States)

    Zhang, Daixiong; Li, Xueming


    Nano-Al/NiO thermites were successfully prepared as film by electrophoretic deposition (EPD). For the key issue of this EPD, a mixture solvent of ethanol-acetylacetone (1:1 in volume) containing 0.00025 M nitric acid was proved to be a suitable dispersion system for EPD. The kinetics of electrophoretic deposition for both nano-Al and nano-NiO were investigated; the linear relation between deposition weight and deposition time in short time and parabolic relation in prolonged time were observed in both EPDs. The critical transition time between linear deposition kinetics and parabolic deposition kinetics for nano-Al and nano-NiO were 20 and 10 min, respectively. The theoretical calculation of the kinetics of electrophoretic deposition revealed that the equivalence ratio of nano-Al/NiO thermites film would be affected by the behavior of electrophoretic deposition for nano-Al and nano-NiO. The equivalence ratio remained steady when the linear deposition kinetics dominated for both nano-Al and nano-NiO. The equivalence ratio would change with deposition time when deposition kinetics for nano-NiO changed into parabolic kinetics dominated after 10 min. Therefore, the rule was suggested to be suitable for other EPD of bicomposites. We also studied thermodynamic properties of electrophoretic nano-Al/NiO thermites film as well as combustion performance.

  20. Electrophoretic particle guidance significantly enhances olfactory drug delivery: a feasibility study.

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    Jinxiang Xi

    Full Text Available BACKGROUND: Intranasal olfactory drug delivery provides a non-invasive method that bypasses the Blood-Brain-Barrier and directly delivers medication to the brain and spinal cord. However, a device designed specifically for olfactory delivery has not yet been found. METHODS: In this study, a new delivery method was proposed that utilized electrophoretic forces to guide drug particles to the olfactory region. The feasibility of this method was numerically evaluated in both idealized 2-D and anatomically accurate 3-D nose models. The influence of nasal airflow, electrode strength, and drug release position were also studied on the olfactory delivery efficiency. FINDINGS: Results showed that by applying electrophoretic forces, the dosage to the olfactory region was significantly enhanced. In both 2-D and 3-D cases, electrophoretic-guided delivery achieved olfactory dosages nearly two orders of magnitude higher than that without electrophoretic forces. Furthermore, releasing drugs into the upper half of the nostril (i.e., partial release led to olfactory dosages two times higher than releasing drugs over the entire area of the nostril. By combining the advantages of pointed drug release and appropriate electrophoretic guidance, olfactory dosages of more than 90% were observed as compared to the extremely low olfactory dosage (<1% with conventional inhaler devices. CONCLUSION: Results of this study have important implications in developing personalized olfactory delivery protocols for the treatment of neurological disorders. Moreover, a high sensitivity of olfactory dosage was observed in relation to different pointed release positions, indicating the importance of precise particle guidance for effective olfactory delivery.

  1. Analytical study of Joule heating effects on electrokinetic transportation in capillary electrophoresis. (United States)

    Xuan, Xiangchun; Li, Dongqing


    Electric fields are often used to transport fluids (by electroosmosis) and separate charged samples (by electrophoresis) in microfluidic devices. However, there exists inevitable Joule heating when electric currents are passing through electrolyte solutions. Joule heating not only increases the fluid temperature, but also produces temperature gradients in cross-stream and axial directions. These temperature effects make fluid properties non-uniform, and hence alter the applied electric potential field and the flow field. The mass species transport is also influenced. In this paper we develop an analytical model to study Joule heating effects on the transport of heat, electricity, momentum and mass species in capillary-based electrophoresis. Close-form formulae are derived for the temperature, applied electrical potential, velocity, and pressure fields at steady state, and the transient concentration field as well. Also available are the compact formulae for the electric current and the volume flow rate through the capillary. It is shown that, due to the thermal end effect, sharp temperature drops appear close to capillary ends, where sharp rises of electric field are required to meet the current continuity. In order to satisfy the mass continuity, pressure gradients have to be induced along the capillary. The resultant curved fluid velocity profile and the increase of molecular diffusion both contribute to the dispersion of samples. However, Joule heating effects enhance the sample transport velocity, reducing the analysis time in capillary electrophoretic separations.

  2. Development and validation of a stability-indicating capillary zone electrophoretic method for the assessment of entecavir and its correlation with liquid chromatographic methods. (United States)

    Dalmora, Sergio Luiz; Nogueira, Daniele Rubert; D'Avila, Felipe Bianchini; Souto, Ricardo Bizogne; Leal, Diogo Paim


    A stability-indicating capillary zone electrophoresis (CZE) method was validated for the analysis of entecavir in pharmaceutical formulations, using nimesulide as an internal standard. A fused-silica capillary (50 µm i.d.; effective length, 40 cm) was used while being maintained at 25°C; the applied voltage was 25 kV. A background electrolyte solution consisted of a 20 mM sodium tetraborate solution at pH 10. Injections were performed using a pressure mode at 50 mbar for 5 s, with detection at 216 nm. The specificity and stability-indicating capability were proven through forced degradation studies, evaluating also the in vitro cytotoxicity test of the degraded products. The method was linear over the concentration range of 1-200 µg mL(-1) (r(2) = 0.9999), and was applied for the analysis of entecavir in tablet dosage forms. The results were correlated to those of validated conventional and fast LC methods, showing non-significant differences (p > 0.05).

  3. Characterization and Study of Transgenic Cultivars by Capillary and Microchip Electrophoresis

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    Elena Domínguez Vega


    Full Text Available Advances in biotechnology have increased the demand for suitable analytical techniques for the analysis of genetically modified organisms. Study of the substantial equivalence, discrimination between transgenic and non-transgenic cultivars, study of the unintended effects caused by a genetic modification or their response to diverse situations or stress conditions (e.g., environmental, climatic, infections are some of the concerns that need to be addressed. Capillary electrophoresis (CE is emerging as an alternative to conventional techniques for the study and characterization of genetically modified organisms. This article reviews the most recent applications of CE for the analysis and characterization of transgenic cultivars in the last five years. Different strategies have been described depending on the level analyzed (DNA, proteins or metabolites. Capillary gel electrophoresis (CGE has shown to be particularly useful for the analysis of DNA fragments amplified by PCR. Metabolites and proteins have been mainly separated using capillary zone electrophoresis (CZE using UV and MS detection. Electrophoretic chips have also proven their ability in the analysis of transgenic cultivars and a section describing the new applications is also included.

  4. The study of polyoxometalates formation using capillary zone electrophoresis. (United States)

    Zdanov, Artem A; Shuvaeva, Olga V


    The formation process of polyoxometalates [PMo12 O40 ](3-) and [PMo12 - x Vx O40 ](-3-x) has been studied in aqueous solutions of 0.1 M malonate buffer at pH 2.8-3.0 using CZE. Two different approaches, pre-capillary and in-capillary, were examined and compared. In precapillary mode, the reaction mixture of the reactants and reaction products was injected into the capillary followed by the separation procedure. In in-capillary mode, the sequential input of the reagents and running electrolyte into the capillary and the species separation occurs simultaneously. The optimal parameters of in-capillary separation were established as functions of applied voltage and the length of the intermediate buffer zone between the reagents in the capillary. As a result the best-compromise conditions for the separation of the mixtures containing the reactants, intermediates, and reaction products, in order to achieve the best efficiency, symmetry, and peak areas, were achieved at -18 kV and the input parameter of 900 mbar·s. It was also shown that in-capillary mode is more informative than pre-capillary mode for studying the complex compound formation process.

  5. Estratégias de pré-concentração em eletroforese capilar (CE: parte 1. Manipulação da velocidade eletroforética do analito Preconcentration strategies in capillary electrophoresis (CE: part 1. Manipulation of the analyte electrophoretic velocity

    Directory of Open Access Journals (Sweden)

    Maria de Lourdes Leite de Moraes


    Full Text Available Capillary electrophoresis has become a well-established and routine-based separation technique. It is based on the differences between charged analyte mobility in aqueous or organic electrolytes. Its major limitation is the sensitivity due to small sample injection volumes and the narrow diameter of the capillaries, especially when UV detection is used. There are a number of ways to increase the concentration sensitivity. This report shows some on-line preconcentration strategies to perform it in free solution capillary electrophoresis that are based on manipulation of the analyte electrophoretic velocity during the sample introduction (stacking, field amplification and transient isotachophoresis.

  6. The sensitive capillary electrophoretic-LIF method for simultaneous determination of curcuminoids in turmeric by enhancing fluorescence intensities of molecules upon inclusion into (2-hydroxypropyl)-β-cyclodextrin. (United States)

    Kalaycıoğlu, Zeynep; Hashemi, Parya; Günaydın, Keriman; Erim, F Bedia


    Curcuminoids have received great attention in the past decades due to their health benefit properties. The aim of this study is to develop a very simple, rapid, and sensitive capillary zone electrophoresis technique coupled with a laser induced fluorescence detector (LIF) for the simultaneous determination of three major curcuminoids of turmeric, namely, curcumin, demethoxy curcumin (DMC), and bisdemethoxy curcumin (BDMC). Background electrolyte was selected as borate at pH 9.6 and (2-hydroxypropyl)-β-cyclodextrin (2-HP-β-CD) was added to prevent rapid alkali degradation of curcuminoids in buffer and to increase fluorescence intensities of molecules. With the addition of 2-HP-β-CD to the separation electrolyte, the fluorescence signal intensities of curcuminoids were enhanced considerably by 30, 40, and 54 fold for curcumin, DMC, and BDMC, respectively. The three curcuminoids of turmeric were fully separated and quantified in less than 4.5 min. The repeatability of the peak areas of curcuminoids for intra-day and inter-day experiments was in the satisfactory range of 2.26 and 2.55%, respectively. The LOD and LOQ values for the developed method were equal to or less than 0.081 and 0.270 μg/mL, respectively, for all curcuminoids. The developed method was successfully applied to find curcuminoids amount in turmeric samples and herbal supplements.

  7. Study of Stability Constants of Fe (Iii And Mn (Ii with Chloramphenicol by Paper Electrophoretic Technique

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    Arvind Singh


    Full Text Available Stabilty constant of binary complexes of Fe(III and Mn(II with medicinally important ligand chloramphenicol antibiotics in solution were determined by paper electrophoretic technique. Stability constant of the complexes were determined at 25°C temperature and 0.1M (HClO4 ionic strength. Our study is based upon the migration of a spot of metal ions on a paper strip at different pH against mobility gives information about the binary complexes and permits to calculate their stability constant. The stability constant data revealed that chloramphenicol may be used as chelating agent in chelation for medical treatment of metal overload or poisoning.

  8. Effect of Joule heating on efficiency and performance for microchip-based and capillary-based electrophoretic separation systems: a closer look. (United States)

    Petersen, Nickolaj J; Nikolajsen, Rikke P H; Mogensen, Klaus B; Kutter, Jörg P


    An attempt is made to revisit the main theoretical considerations concerning temperature effects ("Joule heating") in electro-driven separation systems, in particular lab-on-a-chip systems. Measurements of efficiencies in microfabricated devices under different Joule heating conditions are evaluated and compared to both theoretical models and measurements performed on conventional capillary systems. The widely accepted notion that planar microdevices are less susceptible to Joule heating effects is largely confirmed. The heat dissipation from a nonthermostatically controlled glass microdevice was found to be comparable to that from a liquid-cooled-fused silica capillary. Using typically dimensioned glass and glass/silicon microdevices, the experimental results indicate that 5-10 times higher electric field strengths can be applied than on conventional capillaries, before detrimental effects on the separation efficiency occur. The main influence of Joule heating on efficiency is via the establishment of a radial temperature profile across the lumen of the capillary or channel. An overall temperature increase of the buffer solution has only little influence on the quality of the separation. Still, active temperature control (cooling, thermostatting) can help prevent boiling of the buffer and increase the reproducibility of the results.

  9. Graphene/poly(ethylene-co-vinyl acetate) composite electrode fabricated by melt compounding for capillary electrophoretic determination of flavones in Cacumen platycladi. (United States)

    Sheng, Shijun; Liu, Shuang; Zhang, Luyan; Chen, Gang


    In this report, a graphene/poly(ethylene-co-vinyl acetate) composite electrode was fabricated by melt compounding for the amperometric detection of capillary electrophoresis. The composite electrode was fabricated by packing a mixture of graphene and melted poly(ethylene-co-vinyl acetate) in a piece of fused silica capillary under heat. The structure of the composite was investigated by scanning electron microscopy and Fourier transform infrared spectroscopy. The results indicated that graphene sheets were well dispersed in the composite to form an interconnected conducting network. The performance of this unique graphene-based detector has been demonstrated by separating and detecting rutin, quercitrin, kaempferol, and quercetin in Cacumen platycladi in combination with capillary electrophoresis. The four flavones have been well separated within 9 min in a 50-cm-long capillary at a separation voltage of 12 kV using a 50 mM sodium borate buffer (pH 9.2). The graphene-based detector offered significantly lower operating potentials, substantially enhanced signal-to-noise characteristics, lower expense of operation, high resistance to surface fouling, and enhanced stability. It showed long-term stability and repeatability with relative standard deviations of <5% for the peak current (n = 15).

  10. Application of capillary electrophoresis to the simultaneous determination and stability study of four extensively used penicillin derivatives

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    Brigitta Simon


    Full Text Available The applicability of capillary electrophoresis for the analysis of four extensively used penicillin derivatives (benzylpenicillin, ampicillin, amoxicillin, oxacilllin has been studied. Because of structural similarities, the electrophoretic behavior of these derivatives is very similar; consequently an efficient separation using the conventional capillary zone electrophoresis is hard to be achieved. Their simultaneous separation was solved by using micellar electrokinetic capillary chromatography, the separation being based on the differential partition of the analytes between the micellar and aqueous phase. Using a buffer solution containing 25 mM sodium tetraborate and 100 mM sodium dodecyl sulfate as surfactant, at a pH of 9.3, applying a voltage of + 25 kV at a temperature of 25 °C, we achieved the simultaneous separation of the studied penicillin derivatives in less then 5 minutes. The separation conditions were optimized and the analytical performance of the method was evaluated in terms of precision, linearity, limit of detection, and quantification. Also, a simple capillary zone electrophoresis method was applied to study the stability of the studied penicillin derivatives in water at different temperatures, using ciprofloxacin hydrochloride as internal standard. It was observed that the extent of the hydrolysis of penicillins in water is highly dependent on the time and also temperature.

  11. Capillary electrophoresis in a fused-silica capillary with surface roughness gradient. (United States)

    Horká, Marie; Šlais, Karel; Karásek, Pavel; Růžička, Filip; Šalplachta, Jiří; Šesták, Jozef; Kahle, Vladislav; Roth, Michal


    The electro-osmotic flow, a significant factor in capillary electrophoretic separations, is very sensitive to small changes in structure and surface roughness of the inner surface of fused silica capillary. Besides a number of negative effects, the electro-osmotic flow can also have a positive effect on the separation. An example could be fused silica capillaries with homogenous surface roughness along their entire separation length as produced by etching with supercritical water. Different strains of methicillin-resistant and methicillin-susceptible Staphylococcus aureus were separated on that type of capillaries. In the present study, fused-silica capillaries with a gradient of surface roughness were prepared and their basic behavior was studied in capillary zone electrophoresis with UV-visible detection. First the influence of the electro-osmotic flow on the peak shape of a marker of electro-osmotic flow, thiourea, has been discussed. An antifungal agent, hydrophobic amphotericin B, and a protein marker, albumin, have been used as model analytes. A significant narrowing of the detected zones of the examined analytes was achieved in supercritical-water-treated capillaries as compared to the electrophoretic separation in smooth capillaries. Minimum detectable amounts of 5 ng/mL amphotericin B and 5 μg/mL albumin were reached with this method.

  12. Study of a heat rejection system using capillary pumping (United States)

    Neal, L. G.; Wanous, D. J.; Clausen, O. W.


    Results of an analytical study investigating the application of capillary pumping to the heat rejection loop of an advanced Rankine cycle power conversion system are presented. The feasibility of the concept of capillary pumping as an alternate to electromagnetic pumping is analytically demonstrated. Capillary pumping is shown to provide a potential for weight and electrical power saving and reliability through the use of redundant systems. A screen wick pump design with arterial feed lines was analytically developed. Advantages of this design are high thermodynamic and hydrodynamic efficiency, which provide a lightweight easily packaged system. Operational problems were identified which must be solved for successful application of capillary pumping. The most important are the development of start up and shutdown procedures, and development of a means of keeping noncondensibles from the system and of earth-bound testing procedures.

  13. Capillary Electrophoresis in the Analysis of Polyunsaturated Fatty Acids

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    Gabriel Hancu


    Full Text Available The aim of this study to inventory the main electrophoretic methods for identification and quantitative determination of fatty acids from different biological matrices. Critical analysis of electrophoretic methods reported in the literature show that the determination of polyunsaturated fatty acids can be made by: capillary zone electrophoresis, micellar electrokinetic chromatography and microemulsion electrokinetic chromatography using different detection systems such as ultraviolet diode array detection, laser induced fluorescence or mass – spectrometry. Capillary electrophoresis is a fast, low-cost technique used for polyunsaturated fatty acids analysis although their determination is mostly based on gas chromatography.

  14. An electrophoretic study of myosin heavy chain expression in skeletal muscles of the toad Bufo marinus. (United States)

    Nguyen, L T; Stephenson, G M


    In this study we developed an SDS-PAGE protocol which for the first time separates effectively all myosin heavy chain (MHC) isoforms expected to be expressed in iliofibularis (IF), pyriformis (PYR), cruralis (CRU) and sartorius (SAR) muscles of the toad Bufo marinus on the basis of previously reported fibre type composition. The main feature of the method is the use of alanine instead of glycine both in the separating gel and in the running buffer. The correlation between the MHC isoform composition of IF, SAR and PYR muscles determined in this study and the previously reported fibre type composition of IF and SAR muscles in the toad and of PYR muscle in the frog was used to tentatively identify the MHC isoforms expressed by twitch fibre types 1, 2 and 3 and by tonic fibres. The alanine-SDS electrophoretic method was employed to examine changes in the MHC composition of IF, PYR, CRU and SAR muscles with the ontogenetic growth of the toad from post-natal life (body weight muscle observed in this study are in very good agreement with those in the fibre type composition of the developing IF muscle reported in the literature.

  15. Experimental study on capillary filling in nanochannels (United States)

    Yang, Min; Cao, Bing-Yang; Wang, Wei; Yun, He-Ming; Chen, Bao-Ming


    We investigated the capillary filling kinetics of deionized water in nanochannels with heights of 50-120 nm. The measured position of the moving meniscus was proportional to the square root of time, as predicted by the LW equation. However, the extracted slopes were significantly smaller than the predictions based on the bulk properties. This unusual behavior was found to be mainly caused by the electro-viscous effect and dynamic contact angle, which was significantly larger than the static angle. In addition, when the filling distance reached about 600 μm, bubbles tended to be formed, leading to the main meniscus was almost immobile.

  16. Studies on electrophoretically deposited nanostructured barium titanate systems and carrier transport phenomena (United States)

    Borah, Manjit; Mohanta, Dambarudhar


    We report on the development of nanostructured barium titanate (BaTiO3, BT) films on ~200-μm-thick Ag substrates by employing a cathodic electrophoretic deposition (EPD) technique, where solid-state-derived BT nanoparticles are used as the starting material. Structural, morphological and compositional analyses of the as-synthesized BT nanoparticles and films were performed by X-ray diffraction, electron microscopy and energy-dispersive spectroscopy studies. The synthesized nano-BT system has an average crystallite size of ~8.1 nm and a tetragonality ( c/ a) value ~1.003. To reveal current transport mechanism, the BT films possessing microporous structures and surrounded by homogeneously grown islands were assessed in a metal-insulator-metal (MIM) conformation. The forward current conduction was observed to be purely thermionic up to respective voltages of ~1.4 and 2.2 V as for the fresh and 3-day aged samples. On the other hand, direct tunneling (DT)-mediated Ohmic feature was witnessed at a comparatively higher voltage, beyond which Fowler-Nordheim tunneling (FN) dominates in the respective MIM junctions. The magnitude of current accompanied by FN process was observed to be stronger in reverse biasing than that of forward biasing case. The use of microporous BT films can offer new insights as regards regulated tunneling events meant for miniaturized nanoelectronic elements/components.

  17. Interactions of non-charged tadalafil stereoisomers with cyclodextrins: capillary electrophoresis and nuclear magnetic resonance studies. (United States)

    Fejős, Ida; Kazsoki, Adrienn; Sohajda, Tamás; Márványos, Ede; Volk, Balázs; Szente, Lajos; Béni, Szabolcs


    The single isomer drug R,R-tadalafil (Cialis) contains two chiral centers thus four stereoisomers (R,R-, S,S-, S,R- and R,S-tadalafil) exist, however, only the most potent inhibitor, the R,R-tadalafil is in clinical use. In our study, over 20 charged cyclodextrin (CD) derivatives were studied for enantiospecific host-guest type interactions in CD-modified capillary electrophoresis. Tadalafil stereoisomers are non-charged; therefore, their electrophoretic separation poses a challenge. Several candidates of both positively and negatively charged hosts were found to be effective for the enantioseparation. Eight out of the beta derivatives and three of alpha derivatives (including sulfated, sulfoalkylated, carboxyalkylated and amino derivatives) resolved all four stereoisomers partially or completely. Cavity size-dependent absolute enantiomer migration order (EMO) reversals were observed in the case of sulfopropyl-alpha (EMO: R,S; S,R; R,R; S,S) and sulfopropyl-beta (S,S; R,R; S,R; R,S) derivatives, while substituent-dependent partial EMO reversals were detected for sulfobutyl-ether-alpha (R,S; S,R; S,S; R,R) and sulfated-alpha-CD (R,R; S,S; R,S; S,R) selectors. Complexation-induced (1)H NMR chemical shift changes reflected that the benzodioxole moiety plays a major role in cavity size-dependent EMO reversal. Sulfobutyl-ether-alpha-CD was the only selector that provided the desired EMO in which the clinically applied eutomer R,R-tadalafil migrates last. Finally, an electrophoretic method applying a background electrolyte (BGE) containing 75 mM Tris-acetic acid buffer (pH 4.75) and 7 mM sulfobutyl-ether-alpha-CD was developed for the baseline resolution of all isomers at 25 °C and +25 kV applied voltage.

  18. Study of preparation of BG/HA gradient coating on titanium alloy by electrophoretic deposition method

    Institute of Scientific and Technical Information of China (English)

    CHEN Xiao-ming; HAN Qing-rong; LI Shi-pu; XU Chuan-bo


    In this paper, a gradient bioactive coating made from modified bioglass (BG) and hydroxyapatite (HA) was prepared by electrophoretic deposition method(EPD)on the surface of titanium alloy. Strong bonding between the matrix and BG/HA gradient coating was got by sintering. Crystal composition of the coating was analyzed by XRD. The characteristics of surface and cross section of the coating were observed by SEM. Adhesive strength of the coating was tested by pull method. The optimizing technological parameters were determined.

  19. Hypotrichosis with keratosis pilaris: electrophoretical study of hair fibrous proteins from a patient. (United States)

    Dekio, S; Nagashima, T; Watanabe, Y; Jidoi, J


    S-carboxymethylated (SCM) fibrous proteins from the scalp hair of a patient with hypotrichosis with keratosis pilaris (HTKP) and from that of a normal individual were analyzed using two-dimensional electrophoresis. One SCM fibrous protein component was different electrophoretically in the HTKP patient. It is suggested that the brittleness of the HTKP hair might result from this alteration of the fibrous protein composition of the hair.

  20. Capillary zone electrophoresis for determination of vildagliptin (a DPP-4 inhibitor) in pharmaceutical formulation and comparative study with HPLC. (United States)

    Barden, A T; Piccoli, B L; Volpato, N M; Schapoval, E E S; Steppe, M


    A stability-indicating capillary zone electrophoresis (CZE) method was validated for the determination of vildagliptin (VLG) in pharmaceutical dosage forms using ranitidine hydrochloride (RH) as internal standard. The CZE method was carried out in a fused silica capillary (64.5 cm total length and 56.0 cm effective length, 50 microm i.d.) by applying a potential of 25 kV (positive polarity), hydrodynamic injection by 50 mbar for 5 s and the temperature of the capillary cartridge was 25 degreesC. The selected background electrolyte (BGE) consisted of 25 mM potassium phosphate (pH 8.0) with UV/PDA detection at 207 nm. The electrophoretic separation was obtained within 6 min and was linear in the range of 50-200 microg/mL (r= 0.9994). The specificity and the stability-indicating capability were demonstrated through degradation studies, which also showed that there was no interference of the formulation excipients. The method was validated in accordance to ICH guidelines acceptance criteria for specificity, linearity, precision, accuracy, robustness and system suitability. The proposed method was compared with HPLC method previously validated for this drug, and statistical analysis showed no significant difference between the methods.

  1. Protonation of phosphate on the surface of goethite as studied by CIR-FTIR and electrophoretic mobility

    Energy Technology Data Exchange (ETDEWEB)

    Tejedor-Tejedor, M.I.; Anderson, M.A. (Univ. of Wisconsin, Madison (USA))


    CIR-FTIR in situ spectroscopic studies have provided evidence for the formation of three different type of complexes, protonated and nonprotonated bridging bidentate as well as a nonprotonated monodentate, between orthophosphate ions and surface Fe(III) of {alpha}-FeOOH particles in aqueous suspensions. The speciation of these complexes is a function of pH and phosphate surface coverage ({Lambda}). Furthermore, the combination of CIR-FTIR, adsorption isotherm, and electrophoretic mobility data allows them to calculate the intrinsic pK value (4.6) for the bridging bidentate iron phosphate surface complex.

  2. Evaluation of migration behaviour of therapeutic peptide hormones in capillary electrophoresis using polybrene-coated capillaries. (United States)

    Aptisa, Ghiulendan; Benavente, Fernando; Sanz-Nebot, Victoria; Chirila, Elisabeta; Barbosa, José


    Modelling electrophoretic mobility as a function of pH can be simultaneously used for determination of ionization constants and for rapid selection of the optimum pH for separation of mixtures of the modelled compounds. In this work, equations describing the effect of pH on electrophoretic behaviour were used to investigate migration of a series of polyprotic amphoteric peptide hormones between pH 2 and 12 in polybrene-coated capillaries. Polybrene (hexadimethrin bromide) is a polymer composed of quaternary amines that is strongly adsorbed by the fused-silica inner surface, preventing undesired interactions between the peptides and the inner capillary wall. In polybrene-coated capillaries the separation voltage must be reversed, because of the anodic electroosmotic flow promoted by the polycationic polymer attached to the inner capillary wall. The possibility of using polybrene-coated capillaries for determination of accurate ionization constants has been evaluated and the optimum pH for separation of a mixture of the peptide hormones studied has been selected. Advantages and disadvantages of using bare fused-silica and polybrene-coated capillaries for these purposes are discussed.

  3. Nonaqueous capillary electrophoresis of dextromethorphan and its metabolites. (United States)

    Pelcová, Marta; Langmajerová, Monika; Cvingráfová, Eliška; Juřica, Jan; Glatz, Zdeněk


    This study deals with the nonaqueous capillary electrophoretic separation of dextromethorphan and its metabolites using a methanolic background electrolyte. The optimization of separation conditions was performed in terms of the resolution of dextromethorphan and dextrorphan and the effect of separation temperature, voltage, and the characteristics of the background electrolyte were studied. Complete separation of all analytes was achieved in 40 mM ammonium acetate dissolved in methanol. Hydrodynamic injection was performed at 3 kPa for 4 s. The separation voltage was 20 kV accompanied by a low electric current. The ultraviolet detection was performed at 214 nm, the temperature of the capillary was 25°C. These conditions enabled the separation of four analytes plus the internal standard within 9 min. Further, the developed method was validated in terms of linearity, sensitivity, and repeatability. Rat liver perfusate samples were subjected to the nonaqueous capillary electrophoretic method to illustrate its applicability.

  4. Ionic concentration- and pH-dependent electrophoretic mobility as studied by single colloid electrophoresis

    Energy Technology Data Exchange (ETDEWEB)

    Semenov, I; Papadopoulos, P; Kremer, F [Institute for Experimental Physics I (MOP), University of Leipzig, Linnestrasse 5, 04103 Leipzig (Germany); Stober, G, E-mail: friedrich.kremer@physik.uni-leipzig.d [Institute of Atmospheric Physics, University of Rostock, Schlossstrasse 6, 18225 Kuehlungsborn (Germany)


    Optical tweezers are employed to measure separately the complex electrophoretic mobility of a single colloid and the complex electroosmotic response of the surrounding medium in a specially designed microfluidic cell. Using the very same colloid both quantities are determined in dependence on the concentration of the aqueous salt solution (10{sup -5}-10{sup -1} mol l{sup -1}), the valence of the ions (K{sup +}, Ca{sup 2+}) and the pH (2.5-8.5). A pronounced effect is observed for all these examined parameters. The dependence on ion concentration agrees qualitatively-for the monovalent case-with the predictions of the standard electrokinetic model.


    Institute of Scientific and Technical Information of China (English)

    WangMing; LiWei; 等


    Using a standard photolithographical procedure,chenmical wet etching and thermal diffusion bonding technology,a chemical analysis device for Capillary Electrophoresis(CE) has been microfabricated on a planar glass substrate with a cross-column geometry.The channels on the microchip substrate are about 50um deep and 150um wide.By employing amino acids derived from 2,4-DiNitroFluoroBenzen(DNFB) on CE chip channels,the sample manipulating system is studied based on the principle of electrodynamics.


    Institute of Scientific and Technical Information of China (English)

    Wang Ming; Li Wei; Han Jinghong; Cui Dafu


    Using a standard photolithographical procedure, chemical wet etching and thermal diffusion bonding technology, a chemical analysis device for Capillary Electrophoresis(CE) has been microfabricated on a planar glass substrate with a cross-column geometry. The channels on the microchip substrate are about 50μm deep and 150μm wide. By employing amino acids derived from 2,4-DiNitroFluoroBenzen (DNFB) on CE chip channels, the sample manipulating system is studied based on the principle of electrodynamics.

  7. A comparative study of Raman enhancement in capillaries (United States)

    Eftekhari, Fatemeh; Irizar, Juan; Hulbert, Laila; Helmy, Amr S.


    This work reports on the comparative studies of Raman enhancement in liquid core waveguides (LCWs). The theoretical considerations that describe Raman enhancement in LCWs is adapted to analyze and compare the performance of hollow core photonic crystal fibers (HCPCFs) to conventional Teflon capillary tubes. The optical losses in both platforms are measured and used to predict their performance for different lengths. The results show that for an optimal waveguide length, two orders of magnitude enhancement in the Raman signal can be achieved for aqueous solutions using HCPCFs. This length, however, cannot be achieved using normal capillary effects. By integrating the interface of the fluidic pump and the HCPCF into a microfluidic chip, we are able to control fluid transport and fill longer lengths of HCPCFs regardless of the viscosity of the sample. The long-term stability and reproducibility of Raman spectra attained through this platform are demonstrated for naphthalenethiol, which is a well-studied organic compound. Using the HCPCF platform, the detection limit of normal Raman scattering in the range of micro-molars has been achieved. In addition to the higher signal-to-noise ratio of the Raman signal from the HCPCF-platform, more Raman modes of naphthalenethiol are revealed using this platform.

  8. In-capillary self-assembly study of quantum dots and protein using fluorescence coupled capillary electrophoresis. (United States)

    Wang, Jianhao; Li, Jingyan; Li, Jinchen; Qin, Yuqin; Wang, Cheli; Qiu, Lin; Jiang, Pengju


    As a vast number of novel materials in particular inorganic nanoparticles have been invented and introduced to all aspects of life, public concerns about how they might affect our ecosystem and human life continue to arise. Such incertitude roots at a fundamental question of how inorganic nanoparticles self-assemble with biomolecules in solution. Various techniques have been developed to probe the interaction between particles and biomolecules, but very few if any can provide advantages of both rapid and convenient. Herein, we report a systematic investigation on quantum dots (QDs) and protein self-assembly inside a capillary. QDs and protein were injected to a capillary one after another. They were mixed inside the capillary when a high voltage was applied. Online separation and detection were then achieved. This new method can also be used to study the self-assembly kinetics of QDs and protein using the Hill equation, the KD value for the self-assembly of QDs and protein was calculated to be 8.8 μM. The obtained results were compared with the previous out of-capillary method and confirmed the effectiveness of the present method.

  9. Principles of Micellar Electrokinetic Capillary Chromatography Applied in Pharmaceutical Analysis


    Árpád Gyéresi; Eleonora Mircia; Brigitta Simon; Aura Rusu; Gabriel Hancu


    Since its introduction capillary electrophoresis has shown great potential in areas where electrophoretic techniques have rarely been used before, including here the analysis of pharmaceutical substances. The large majority of pharmaceutical substances are neutral from electrophoretic point of view, consequently separations by the classic capillary zone electrophoresis; where separation is based on the differences between the own electrophoretic mobilities of the analytes; are hard to achieve...

  10. Particle separations by electrophoretic techniques

    Energy Technology Data Exchange (ETDEWEB)

    Ballou, N.E.; Petersen, S.L.; Ducatte, G.R.; Remcho, V.T.


    A new method for particle separations based on capillary electrophoresis has been developed and characterized. It uniquely separates particles according to their chemical nature. Separations have been demonstrated with chemically modified latex particles and with inorganic oxide and silicate particles. Separations have been shown both experimentally and theoretically to be essentially independent of particle size in the range of about 0.2 {mu}m to 10 {mu}m. The method has been applied to separations of U0{sub 2} particles from environmental particulate material. For this, an integrated method was developed for capillary electrophoretic separation, collection of separated fractions, and determinations of U0{sub 2} and environmental particles in each fraction. Experimental runs with the integrated method on mixtures of UO{sub 2} particles and environmental particulate material demonstrated enrichment factors of 20 for UO{sub 2} particles in respect to environmental particles in the U0{sub 2}containing fractions. This enrichment factor reduces the costs and time for processing particulate samples by the lexan process by a factor of about 20.

  11. Physico-chemical characterization of liposomes and drug substance-liposome interactions in pharmaceutics using capillary electrophoresis and electrokinetic chromatography

    DEFF Research Database (Denmark)

    Franzen, Ulrik; Østergaard, Jesper


    Liposomes are self-assembled phospholipid vesicles and have numerous research and therapeutic applications. In the pharmaceutical and biomedical sciences liposomes find use as models of biological membranes, partitioning medium and as drug carriers. The present review addresses the use of capillary...... electrophoresis and liposome electrokinetic chromatography for the characterization of liposomes in a pharmaceutical context. Capillary electrophoretic techniques have been used for the measurement of electrophoretic mobility, which provides information on liposome surface charge, size and membrane permeability...... of liposomes. The use of liposome electrokinetic chromatography and capillary electrophoresis for determination of liposome/water partitioning and characterization of drug-liposome interactions is reviewed. A number of studies indicate that capillary electrophoresis may have a role in the characterization...

  12. An electrophoretic and cytological study of hybridisation between Aconitum napellus ssp. skerisorae (2n= 32) and A. variegatum (2n= 16). I Electrophoretic evidence


    Roman Zieliński


    The variability of six enzymes in pure and mixed populations of Aconitum napellus and A. variegatum, both from the Tatra Mountains was analysed by means of electrophoresis on starch and polyacrylamide gels. The enzymes differentiating the studied species are: glutamate dehydrogenase, isocitrate dehydrogenase, esterases and peroxidases. A group of plants was isolated with phenotypes intermediate between A. napellus and A. variegatum. Among them were most probably both F1 and introgressive hybr...

  13. An electrophoretic and cytological study of hybridisation between Aconitum napellus ssp. skerisorae (2n= 32 and A. variegatum (2n= 16. I Electrophoretic evidence

    Directory of Open Access Journals (Sweden)

    Roman Zieliński


    Full Text Available The variability of six enzymes in pure and mixed populations of Aconitum napellus and A. variegatum, both from the Tatra Mountains was analysed by means of electrophoresis on starch and polyacrylamide gels. The enzymes differentiating the studied species are: glutamate dehydrogenase, isocitrate dehydrogenase, esterases and peroxidases. A group of plants was isolated with phenotypes intermediate between A. napellus and A. variegatum. Among them were most probably both F1 and introgressive hybrids.

  14. A many-body dissipative particle dynamics study of forced water-oil displacement in capillary. (United States)

    Chen, Chen; Zhuang, Lin; Li, Xuefeng; Dong, Jinfeng; Lu, Juntao


    The forced water-oil displacement in capillary is a model that has important applications such as the groundwater remediation and the oil recovery. Whereas it is difficult for experimental studies to observe the displacement process in a capillary at nanoscale, the computational simulation is a unique approach in this regard. In the present work, the many-body dissipative particle dynamics (MDPD) method is employed to simulate the process of water-oil displacement in capillary with external force applied by a piston. As the property of all interfaces involved in this system can be manipulated independently, the dynamic displacement process is studied systematically under various conditions of distinct wettability of water in capillary and miscibility between water and oil as well as of different external forces. By analyzing the dependence of the starting force on the properties of water/capillary and water/oil interfaces, we find that there exist two different modes of the water-oil displacement. In the case of stronger water-oil interaction, the water particles cannot displace those oil particles sticking to the capillary wall, leaving a low oil recovery efficiency. To minimize the residual oil content in capillary, enhancing the wettability of water and reducing the external force will be beneficial. This simulation study provides microscopic insights into the water-oil displacement process in capillary and guiding information for relevant applications.

  15. Study on Dicarboxylic Acids in Aerosol Samples with Capillary Electrophoresis

    Directory of Open Access Journals (Sweden)

    Heidi Adler


    Full Text Available The research was performed to study the simultaneous detection of a homologous series of α, ω-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 μL. 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.

  16. Quantitative study of electrophoretic and electroosmotic enhancement during alternating current iontophoresis across synthetic membranes. (United States)

    Yan, Guang; Li, S Kevin; Peck, Kendall D; Zhu, Honggang; Higuchi, William I


    One of the primary safety and tolerability limitations of direct current iontophoresis is the potential for electrochemical burns associated with the necessary current densities and/or application times required for effective treatment. Alternating current (AC) transdermal iontophoresis has the potential to eliminate electrochemical burns that are frequently observed during direct current transdermal iontophoresis. Although it has been demonstrated that the intrinsic permeability of skin can be increased by applying low-to-moderate AC voltages, transdermal transport phenomena and enhancement under AC conditions have not been systematically studied and are not well understood. The aim of the present work was to study the fundamental transport mechanisms of square-wave AC iontophoresis using a synthetic membrane system. The model synthetic membrane used was a composite Nuclepore membrane. AC frequencies ranging from 20 to 1000 Hz and AC fields ranging from 0.25 to 0.5 V/membrane were investigated. A charged permeant, tetraethyl ammonium, and a neutral permeant, arabinose, were used. The transport studies showed that flux was enhanced by increasing the AC voltage and decreasing AC frequency. Two theoretical transport models were developed: one is a homogeneous membrane model; the other is a heterogeneous membrane model. Experimental transport data were compared with computer simulations based on these models. Excellent agreement between model predictions and experimental data was observed when the data were compared with the simulations from the heterogeneous membrane model.

  17. Enhanced electrophoretic DNA separation in photonic crystal fiber. (United States)

    Sun, Yi; Nguyen, Nam-Trung; Kwok, Yien Chian


    Joule heating generated by the electrical current in capillary electrophoresis leads to a temperature gradient along the separation channel and consequently affects the separation quality. We describe a method of reducing the Joule heating effect by incorporating photonic crystal fiber into a micro capillary electrophoresis chip. The photonic crystal fiber consists of a bundle of extremely narrow hollow channels, which ideally work as separation columns. Electrophoretic separation of DNA fragments was simultaneously but independently carried out in 54 narrow capillaries with a diameter of 3.7 microm each. The capillary bundle offers more efficient heat dissipation owing to the high surface-to-volume ratio. Under the same electrical field strength, notable improvement in resolution was obtained in the capillary bundle chip.

  18. Study of Oxidation of Glutathione by Capillary Electrophoresis

    Institute of Scientific and Technical Information of China (English)


    A capillary electrophoresis method for the separation and quantification of reduced glutathione (GSH) and oxidized glutathione (GSSG) was developed. A baseline separation was achieved within five minutes. The effects of time and the concentrations of hydrogen peroxide (H2O2) on the oxidation of GSH were investigated.

  19. Capillaries for use in a multiplexed capillary electrophoresis system (United States)

    Yeung, E.S.; Chang, H.T.; Fung, E.N.


    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.

  20. A simple method for assessment and minimization of errors in determination of electrophoretic or electroosmotic mobilities and velocities associated with the axial electric field distortion. (United States)

    Nowak, Paweł Mateusz; Woźniakiewicz, Michał; Kościelniak, Paweł


    It is commonly accepted that the modern CE instruments equipped with efficient cooling system enable accurate determination of electrophoretic or electroosmotic mobilities. It is also often assumed that velocity of migration in a given buffer is constant throughout the capillary length. It is simultaneously neglected that the noncooled parts of capillary produce extensive Joule heating leading to an axial electric field distortion, which contributes to a difference between the effective and nominal electric field potentials and between velocities in the cooled and noncooled parts of capillary. This simplification introduces systematic errors, which so far were however not investigated experimentally. There was also no method proposed for their elimination. We show a simple and fast method allowing for estimation and elimination of these errors that is based on combination of a long-end and short-end injections. We use it to study the effects caused by variation of temperature, electric field, capillary length, and pH.

  1. Determination of vanillin in vanilla perfumes and air by capillary electrophoresis. (United States)

    Minematsu, Saaya; Xuan, Guang-Shan; Wu, Xing-Zheng


    The present study investigated capillary electrophoretic detection of vanillin in vanilla perfume and air. An UV-absorbance detector was used in a home-made capillary electrophoretic instrument. A fused silica capillary (outer diameter: 364 μm, inner diameter: 50 μm) was used as a separation capillary, and a high electric voltage (20 kV) was applied across the two ends of the capillary. Total length of the capillary was 70 cm, and the effective length was 55 cm. Experimental results showed that the vanillin peak was detected at about 600, 450, and 500 seconds when pH of running buffers in CE were 7.2, 9.3, and 11.5, respectively. The peak area of vanillin was proportional to its concentration in the range of 0-10(-2) mol/L. The detection limit was about 10(-5) mol/L. Vanillin concentration in a 1% vanilla perfume sample was determined to be about 3×10(-4) mol/L, agreed well with that obtained by a HPLC method. Furthermore, determination of vanillin in air by combination of CE and active carbon adsorption method was investigated.

  2. Study on the interrelated effects of capillary diameter, background electrolyte concentration, and flow rate in pressure assisted capillary electrophoresis with contactless conductivity detection. (United States)

    Mai, Thanh Duc; Hauser, Peter C


    A detailed study on the effect of the buffer concentration and the magnitude of the superimposed hydrodynamic flow on separation performance in CZE with contactless conductivity detection was carried out with capillaries of 10, 25, and 50 μm internal diameter. It was confirmed that capillaries of narrow internal diameters require higher buffer concentrations for best sensitivities. For all diameters it was found that electrodispersion was the most pronounced band-broadening factor for relatively long residence times. For shorter times, Joule heating related band broadening appears to be the most significant factor, which means that best separation efficiencies are obtained with the narrowest capillaries. As detection limits are as good for capillaries of 10 μm internal diameters as for the other diameters when using contactless conductivity detection, these narrow capillaries are, therefore, generally of benefit when employing this detection technique. Hydrodyamic flow was found to have only a very limited effect on band broadening; an effect was only noticeable for the 50 μm capillary and relatively high flow rates.

  3. Pulsed-field capillary electrophoresis: optimizing separation parameters with model mixtures of sulfonated polystyrenes. (United States)

    Sudor, J; Novotny, M V


    The electrophoretic transport of high molecular weight charged solutes, both flexible and stiff polymers, has been studied by capillary electrophoresis under constant-field and pulsed-field conditions. Sulfonated polystyrenes were used as model solutes in different entangled polymer solutions. First, changes of the end-to-end distance vectors of flexible polymers were examined through the mobility/potential-gradient curves. Under pulsed-field conditions, the influence of different pulse shapes, frequencies, and amplitudes of forward and backward pulses on the electrophoretic mobilities of model solutes was studied. Resolution of the mixture components was strongly affected by changes in frequency of both sine-wave and square-wave pulses. The experimental results obtained under pulse-field conditions are roughly in agreement with the existing theories of electrophoretic transport.

  4. Microchip capillary electrophoresis for frontal analysis of free bilirubin and study of its interaction with human serum albumin. (United States)

    Nie, Zhou; Fung, Ying Sing


    To meet the need for bedside monitoring of free bilirubin for neonates under critical conditions, a microfluidic chip was fabricated and tested for its coupling with CE/frontal analysis (FA) to determine free bilirubin and study of its binding interaction with HSA, which regulated its concentration in plasma. The poly(methyl methacrylate) (PMMA) multichannel chip was fabricated by CO2 laser ablation and bonded with a fused-silica separation capillary for CE/FA separation with UV detection. The chip was designed to allow a complete assay of four electrophoretic runs using preconditioned channels to speed up the determination of free bilirubin and to deliver quick results for bedside monitoring. Under optimized conditions, the linear working range for free bilirubin was from 10 to 200 micromol with RSDs from 2.1 to 5.0% for n=3, and the LOD at 9 micromol for S/N=3. From a binding study between bilirubin and HSA under FA condition, the second binding constant for bilirubin-HSA was determined as 1.07x10(5) L/mol and the number of binding sites per HSA as 3.46. The results enabled the calculation of free bilirubin for jaundiced infants based on the clinically significant level of total bilirubin, producing a range of 118.3-119.4 micromol/L. The developed method is shown to meet the clinical requirement with additional margin of protection to detect the early rising level of free bilirubin prior to jaundice condition. The low-cost microchip CE/FA device is shown to produce quick results with high potential to deliver a suitable bed-side monitoring method for bilirubin management in neonates.

  5. In vitro genotypic variation of Campylobacter coli documented by pulsed-field gel electrophoretic DNA profiling, implications for epidemiological studies

    DEFF Research Database (Denmark)

    On, Stephen L.W.


    Six isolates of Campylobacter coli from different pig herds were subcultured up to 50 times over a 6-month period and DNA samples suitable for pulsed-field gel electrophoretic (PFGE) profiling prepared at regular (1, 20, 40 and 50 passages) intervals. In 5/6 strains, changes in the banding patterns...... of Sma1, Sal1 and/or BamH1 digests were observed. In one such strain the differences were considered artifactual. However, significant alterations in PFGE profiles between subcultures of four strains were seen, irrespective of the restriction enzyme used. Spontaneous intramolecular genomic rearrangements...... of spontaneous genetic change on PFGE profiles must be considered when evaluating strain relationships. Numerical techniques may aid data interpretation but results must be evaluated cautiously....

  6. Electrophoretic separation of lunar soils in a space manufacturing facility (United States)

    Dunning, J. D.; Snyder, R. S.


    The feasibility of electrophoretic separation of lunar soil into its mineral constituents is discussed in this paper. The process and its applicability to lunar soil separation are considered in light of the special requirements of a space manufacturing effort. Data generated in studies at NASA-Marshall Space Flight Center, which assess the efficiency of electrophoretic separation of lunar soil, are discussed and evaluated.

  7. Principles of Micellar Electrokinetic Capillary Chromatography Applied in Pharmaceutical Analysis

    Directory of Open Access Journals (Sweden)

    Árpád Gyéresi


    Full Text Available Since its introduction capillary electrophoresis has shown great potential in areas where electrophoretic techniques have rarely been used before, including here the analysis of pharmaceutical substances. The large majority of pharmaceutical substances are neutral from electrophoretic point of view, consequently separations by the classic capillary zone electrophoresis; where separation is based on the differences between the own electrophoretic mobilities of the analytes; are hard to achieve. Micellar electrokinetic capillary chromatography, a hybrid method that combines chromatographic and electrophoretic separation principles, extends the applicability of capillary electrophoretic methods to neutral analytes. In micellar electrokinetic capillary chromatography, surfactants are added to the buffer solution in concentration above their critical micellar concentrations, consequently micelles are formed; micelles that undergo electrophoretic migration like any other charged particle. The separation is based on the differential partitioning of an analyte between the two-phase system: the mobile aqueous phase and micellar pseudostationary phase. The present paper aims to summarize the basic aspects regarding separation principles and practical applications of micellar electrokinetic capillary chromatography, with particular attention to those relevant in pharmaceutical analysis.

  8. Principles of micellar electrokinetic capillary chromatography applied in pharmaceutical analysis. (United States)

    Hancu, Gabriel; Simon, Brigitta; Rusu, Aura; Mircia, Eleonora; Gyéresi, Arpád


    Since its introduction capillary electrophoresis has shown great potential in areas where electrophoretic techniques have rarely been used before, including here the analysis of pharmaceutical substances. The large majority of pharmaceutical substances are neutral from electrophoretic point of view, consequently separations by the classic capillary zone electrophoresis; where separation is based on the differences between the own electrophoretic mobilities of the analytes; are hard to achieve. Micellar electrokinetic capillary chromatography, a hybrid method that combines chromatographic and electrophoretic separation principles, extends the applicability of capillary electrophoretic methods to neutral analytes. In micellar electrokinetic capillary chromatography, surfactants are added to the buffer solution in concentration above their critical micellar concentrations, consequently micelles are formed; micelles that undergo electrophoretic migration like any other charged particle. The separation is based on the differential partitioning of an analyte between the two-phase system: the mobile aqueous phase and micellar pseudostationary phase. The present paper aims to summarize the basic aspects regarding separation principles and practical applications of micellar electrokinetic capillary chromatography, with particular attention to those relevant in pharmaceutical analysis.

  9. Column-coupling strategies for multidimensional electrophoretic separation techniques. (United States)

    Kler, Pablo A; Sydes, Daniel; Huhn, Carolin


    Multidimensional electrophoretic separations represent one of the most common strategies for dealing with the analysis of complex samples. In recent years we have been witnessing the explosive growth of separation techniques for the analysis of complex samples in applications ranging from life sciences to industry. In this sense, electrophoretic separations offer several strategic advantages such as excellent separation efficiency, different methods with a broad range of separation mechanisms, and low liquid consumption generating less waste effluents and lower costs per analysis, among others. Despite their impressive separation efficiency, multidimensional electrophoretic separations present some drawbacks that have delayed their extensive use: the volumes of the columns, and consequently of the injected sample, are significantly smaller compared to other analytical techniques, thus the coupling interfaces between two separations components must be very efficient in terms of providing geometrical precision with low dead volume. Likewise, very sensitive detection systems are required. Additionally, in electrophoretic separation techniques, the surface properties of the columns play a fundamental role for electroosmosis as well as the unwanted adsorption of proteins or other complex biomolecules. In this sense the requirements for an efficient coupling for electrophoretic separation techniques involve several aspects related to microfluidics and physicochemical interactions of the electrolyte solutions and the solid capillary walls. It is interesting to see how these multidimensional electrophoretic separation techniques have been used jointly with different detection techniques, for intermediate detection as well as for final identification and quantification, particularly important in the case of mass spectrometry. In this work we present a critical review about the different strategies for coupling two or more electrophoretic separation techniques and the

  10. Capillary electrophoresis with noncovalently bilayer-coated capillaries for stability study of allergenic proteins in simulated gastrointestinal fluids. (United States)

    Zheng, Chang; Liu, Youping; Zhou, Qiuhong; Di, Xin


    A novel noncovalently bilayer-coated capillary using cationic polymer polybrene (PB) and anionic polymer (sodium 4-styrenesulfonate) (PSS) as coatings was prepared. This PB-PSS coating showed good migration-time reproducibility for proteins and high stability in the range of pH 2-10 and in the presence of 1M NaOH, acetonitrile and methanol. Capillary electrophoresis with PB-PSS coated capillaries was successfully applied to quantitatively investigate the stability of bovine serum albumin, ovomucoid, β-lactoglobulin and lysozyme in simulated gastrointestinal fluids. β-lactoglobulin A and β-lactoglobulin B were both stable in simulated gastric fluid with degradation percentages of 34.3% and 17.2% after 60min of incubation, respectively. Bovine serum albumin, ovomucoid and lysozyme were stable in simulated intestinal fluid with degradation percentages of 17.7%, 23.4% and 22.8% after 60min of incubation, respectively. The superiority of the proposed method over sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and capillary electrophoresis with untreated fused silica capillaries was demonstrated and emphasized.

  11. Study on application of capillary plane radiation air conditioning system based on the slope roof (United States)

    Li, Y. G.; Wang, T. T.; Liu, X. L.; Dong, X. Z.


    In this paper, based on the principle of the capillary plane radiation air conditioning system, taking the slope roof as an example, the application of the capillary plane radiation airconditioning system is studied and analysed. Then the numerical solution of differential equations is obtained by the technology of CFD. Finally, we analyze the distribution of indoor temperature of the slope roof and the predicted mean votes (PMV) using Airpak simulation software by establishing a physical model. The results show that the PMV of different sections ranges from 0 to 2.5, which meets the requirement of the comfort. These provide a theoretical basis for application and promotion of capillary plane in the slope roof.

  12. Percolation study for the capillary ascent of a liquid through a granular soil

    CERN Document Server

    Cárdenas-Barrantes, M A; Araujo, N A M


    Capillary rise plays a crucial role in the construction of road embankments in flood zones, where hydrophobic compounds are added to the soil to suppress the rising of water and avoid possible damage of the pavement. Water rises through liquid bridges, menisci and trimers, whose width and connectivity depends on the maximal half-length {\\lambda} of the capillary bridges among grains. Low {\\lambda} generate a disconnect structure, with small clusters everywhere. On the contrary, for high {\\lambda}, create a percolating cluster of trimers and enclosed volumes that form a natural path for capillary rise. Hereby, we study the percolation transition of this geometric structure as a function of {\\lambda} on a granular media of monodisperse spheres in a random close packing. We determine both the percolating threshold {\\lambda}_{c} = (0.049 \\pm 0.004)R (with R the radius of the granular spheres), and the critical exponent of the correlation length {\

  13. Ultrastructural study of the epididymis and the vas deferens and electrophoretic profile of their luminal fluid proteins in the lizard Mabuya carinata. (United States)

    Aranha, I; Bhagya, M; Yajurvedi, H N


    The light microscopy, histochemical and TEM studies of the epididymis and the vas deferens revealed the presence of PAS positive secretory granules in the epithelial cells lining the lumen of these organs. One dimensional SDS gel electrophoretic pattern of luminal fluid proteins and the total protein content of the testis, three regions of the epididymis and the vas deferens of the lizard, Mabuya carinata were studied during breeding and nonbreeding season of the reproductive cycle. During breeding season, 25 protein bands in the testicular luminal fluid, 26 in the anterior epididymal luminal fluid and 28 in the middle and posterior epididymal luminal fluid were found. Ten new protein bands appeared in the anterior epididymal region whereas five new protein bands appeared in the middle region of the epididymis indicating regional difference in protein secretions of the epididymis. Vas deferens luminal fluid showed the highest number of protein bands (32) and the highest total protein content (9.07 mg/ml) compared to the testis and the epididymis. Four new protein bands appeared in the vas deferens. Number of protein bands in the luminal fluids of testis, epididymis and the vas deferens were significantly reduced during nonbreeding season compared to those of the breeding season. Consistent with the decrease in the number of protein bands, there was a significant reduction in the total protein concentration in all the tissue samples during nonbreeding season. The results indicate seasonal differences in number of proteins secreted and quantity of proteins in the luminal fluid of male reproductive tract of M. carinata. This is the first study in reptiles revealing appearance of new proteins in epididymis, and vas deferens by conducting simultaneous electrophoretic profile of testicular, epididymal and vas deferens luminal contents.

  14. Determination of some individual chlorobiphenyls in eel-fat with capillary gaschromatography: collaborative study

    NARCIS (Netherlands)

    Tuinstra, L.G.M.T.; Roos, A.H.; Werdmuller, G.A.


    A method for the determination of six individual chlorobiphenyls in eel-fat, based on saponification of the sample and determination with capillary gas chromatography, was studied collaboratively. Eleven laboratories submitted analytical results in duplo of six individual chlorbiphenyls on two sampl

  15. Experimental study on nonmonotonicity of capillary desaturation curves in a 2-D pore-network

    Energy Technology Data Exchange (ETDEWEB)

    Rodriquez de Castro, Antonio [Univ. of Manchester (United Kingdom); Shokri, Nima [Univ. of Manchester (United Kingdom); Karadimitriou, Nikolaos [Univ. of Manchester (United Kingdom); Oostrom, Martinus [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Joekar-Niasar, Vahid [Univ. of Manchester (United Kingdom)


    Immiscible displacement in a porous medium is important in many applications such as soil remediation and enhanced oil recovery. When gravitational forces are negligible, two-phase immiscible displacement at the pore level is controlled by capillary and viscous forces whose relative importance is quantified through the dimensionless capillary number Ca and the viscosity ratio M between liquid phases. Depending on the values of Ca and M, capillary fingering, viscous fingering, or stable displacement may be observed resulting in a variety of patterns affecting the phase entrapment. The Capillary Desaturation Curve (CDC), which represents the relationship between the residual oils saturation and Ca, is an important relation to describe the phase entrapment at a given Ca. In the present study, we investigate the CDC as influenced by the viscosity ratio. A comprehensive series of experiments using a high-resolution microscope and state-of-the-art micromodels were conducted. The CDCs were calculated and the effects of Ca and M on phase entrapments were quantified. The results show that CDCs are not necessarily monotonic for all M.

  16. Study of capillary network directionality and irrigation of hypoxic tissue in an angiogenesis lattice model (United States)

    Moglia, Belén; Guisoni, Nara; Albano, Ezequiel V.


    To shed light on the understanding of the angiogenesis process, we study a simplified lattice model for the capillary network formation between an existing blood vessel and an initially hypoxic tissue. We consider that the cells of the tissue surface can release growth factors that will diffuse, leading to the formation of new capillaries that ultimately arrive at the tissue. Additionally, we consider the local production of growth factors by the growing capillary network. We also propose the existence of an inhibition mechanism at the hypoxic surface, i.e., a fixed number of neighboring sites of an already irrigated site of the hypoxic tissue stop releasing growth factors due to the arrival of nutrients. Particularly, the goal of this work is to study the effect of the release of local growth factors and the inhibition mechanism on properties such as the directionality of the growing network and the irrigation of the hypoxic tissue. Therefore we propose the quantification of these two relevant features for angiogenesis modeling. We establish a relationship between the model behavior without the release of local growth factors in the presence of the inhibition mechanism and a normal angiogenesis process. In this situation, the model gives a directional capillary network and a good irrigation of the hypoxic tissue. On the other hand, for a large number of released local growth factors in the absence of the inhibition mechanism, the model could be appropriate for the description of tumor angiogenesis. In this case, the model provides a rather small directionality for the growing structure, with a worse degree of irrigation of the hypoxic tissue, as well as a more tortuous capillary network with many closed branches and loops.

  17. A Numerical Modeling Study of Effect of Heterogeneity on Capillary Trapping of Geologically Sequestrated CO2 (United States)

    Cihan, A.; Birkholzer, J. T.; Zhou, Q.; Trevisan, L.; Illangasekare, T. H.; Rodriguez, D.; Sakaki, T.


    Heterogeneities at multiple scales influence migration and trapping of geologically sequestrated CO2 during injection and post-injection periods. Understanding of small-scale processes is crucial to device upscaling methodologies for incorporating them into macroscopic-scale models. The upscaled models are in turn used to get insights into the complex field-scale processes involved in the migration of supercritical CO2. Theoretical research based on numerical model analysis presented in this study focuses on capillary entrapment in homogeneous and heterogeneous small-scale and intermediate-scale laboratory experiments with surrogate fluids, presented in a companion presentation (Treviso et al., 2011). An improved understanding of pore-scale and larger scale processes on capillary entrapment may be achieved by combining pore-scale and macroscopic-scale modeling approaches. Capillarity controlled entrapped non-wetting phase saturation in macroscopic-scale models is generally either provided as an input parameter after laboratory scale measurements or estimated empirically. A particle trajectory modeling approach with pore-scale physics included is used to gain insights to development of physically-based models for the capillary entrapment in homogeneous and heterogeneous systems. The particle trajectory modeling generates functional relationships between phase saturation, entrapped phase saturation, hydraulic properties of the medium, and velocity of injected phase, which eventually are planned to be used for developing macroscopic scale models of capillary entrapment. The predictions of entrapped fluid saturation from the particle trajectory model are verified with measurements from the small scale experimental test systems. Macroscopic two-phase flow modeling approach with existing and modified constitutive models is tested by comparisons with both small-scale and intermediate-scale experimental results. T2VOC module based on TOUGH2 is used to simulate two

  18. Electrophoretically mediated microanalysis for characterization of the enantioselective CYP3A4 catalyzed N-demethylation of ketamine. (United States)

    Ying Kwan, Hiu; Thormann, Wolfgang


    Execution of an enzymatic reaction performed in a capillary with subsequent electrophoretic analysis of the formed products is referred to as electrophoretically mediated microanalysis (EMMA). An EMMA method was developed to investigate the stereoselectivity of the CYP3A4-mediated N-demethylation of ketamine. Ketamine was incubated in a 50 μm id bare fused-silica capillary together with human CYP3A4 Supersomes using a 100 mM phosphate buffer (pH 7.4) at 37°C. A plug containing racemic ketamine and the NADPH regenerating system including all required cofactors for the enzymatic reaction was injected, followed by a plug of the metabolizing enzyme CYP3A4 (500 nM). These two plugs were bracketed by plugs of incubation buffer to ensure proper conditions for the enzymatic reaction. The rest of the capillary was filled with a pH 2.5 running buffer comprising 50 mM Tris, phosphoric acid, and 2% w/v of highly sulfated γ-cyclodextrin. Mixing of reaction plugs was enhanced via application of -10 kV for 10 s. After an incubation of 8 min at 37°C without power application (zero-potential amplification), the capillary was cooled to 25°C within 3 min followed by application of -10 kV for the separation and detection of the formed enantiomers of norketamine. Norketamine formation rates were fitted to the Michaelis-Menten model and the elucidated values for V(max) and K(m) were found to be comparable to those obtained from the off-line assay of a previous study.

  19. Classification of electrophoretic registers from meningitis contaminated rats

    Directory of Open Access Journals (Sweden)

    Luis E Mendoza


    Full Text Available This paper proposes a new method for classification of Capillary Electrophoretic Registers (CER retrieved from cerebrospinal fluid sample taken from meningitis contaminated rats. The proposed approach applies several signal processing tools such as, wavelet analysis (WA, dynamic programming, principal component analysis (PCA and support vector machines (SVM, for data pre-processing, feature extraction and CER classification. Furthermore, an algorithm is developed that detects zones in the CER where local energy variations between study groups (meningitis group and control group are observed. This algorithm help us to identify the effects that Kliebsella Pneumonie (KP bacteria produce in certain substances (aminoacids that are part of the cerebrospinal fluid samples. It is shown that Meningitis disease can be effectively detected, analyzing the CER with the proposed methods. Futhermore, we show that exploiting the information related to the local energy variation improves the classification correctness rate up to 97.3%. This classification performance is obtained using least square SVM (LS-SVM as classification tools and the parameterized CER representation proposed in this paper.

  20. Effects of rosuvastatin on electronegative LDL as characterized by capillary isotachophoresis: the ROSARY Study


    Zhang, Bo; Matsunaga, Akira; Rainwater, David L.; Miura, Shin-ichiro; Noda, Keita; Nishikawa, Hiroaki; Uehara, Yoshinari; Shirai, Kazuyuki; Ogawa, Masahiro; Saku, Keijiro


    Electronegative LDL, a charge-modified LDL (cm-LDL) subfraction that is more negatively charged than normal LDL, has been shown to be inflammatory. We previously showed that pravastatin and simvastatin reduced the electronegative LDL subfraction, fast-migrating LDL (fLDL), as analyzed by capillary isotachophoresis (cITP). The present study examined the effects of rosuvastatin on the more electronegative LDL subfraction, very-fast-migrating LDL (vfLDL), and small, dense charge-modified LDL (sd...

  1. Capillary microreactors for lactic acid extraction: experimental and modelling study

    NARCIS (Netherlands)

    Susanti, Susanti; Winkelman, Jozef; Schuur, Boelo; Heeres, Hero; Yue, Jun


    Lactic acid is an important biobased chemical and, among others, is used for the production of poly-lactic acid. Down-stream processing using state of the art technology is energy intensive and leads to the formation of large amounts of salts. In this presentation, experimental and modeling studies

  2. Capillary sample (United States)

    ... several times a day using capillary blood sampling. Disadvantages to capillary blood sampling include: Only a limited ... do not constitute endorsements of those other sites. Copyright 1997-2017, A.D.A.M., Inc. Duplication ...


    The instability of sulfonylureas in solution in methanol has led us to a kinetic study of methanolysis of two sulfonylureas using capillary electrophoresis. In a preliminary experiment solutions of the seven compounds, bensulfuron methyl, sulfometuron methyl, nicosulfuron, chlori...

  4. A Prospective Study of Villous Capillary Lesions in Complicated Pregnancies

    Directory of Open Access Journals (Sweden)

    Anu Priyadharshini Srinivasan


    Full Text Available The vascularity of placental tissue is dependent on various factors of which fetomaternal hypoxia plays a major role. Hypoxia can be of different types and each type influences the vascularity of the villi, especially terminal villi, in its own way. In this study, we attempted to identify villous vascular changes in a group of term placentae from mothers with diseases complicating pregnancy. Chorangiosis was the most frequently identified lesion while chorangioma was found in only 2 cases. There were no cases of chorangiomatosis. A few cases had normal villous vasculature. Maternal diseases have a major role in disrupting the placental vasculogenesis and angiogenesis by creating a hypoxic environment that may affect the fetus adversely. Hence, such conditions need to be identified early in pregnancy and managed appropriately as it is possible to maintain a normal vasculature and prevent neonatal mortality and morbidity if prompt intervention is done.

  5. Electrophoretic concentration and sweeping-micellar electrokinetic chromatography analysis of cationic drugs in water samples. (United States)

    Wuethrich, Alain; Haddad, Paul R; Quirino, Joselito P


    Sample preparation by electrophoretic concentration, followed by analysis using sweeping-micellar electrokinetic chromatography, was studied as a green and simple analytical strategy for the trace analysis of cationic drugs in water samples. Electrophoretic concentration was conducted using 50 mmol/L ammonium acetate at pH 5 as acceptor electrolyte. Electrophoretic concentration was performed at 1.0 kV for 50 min and 0.5 kV and 15 min for purified and 10-fold diluted waste water samples, respectively. Sweeping-micellar electrokinetic chromatography was with 100 mmol/L sodium phosphate at pH 2, 100 mmol/L sodium dodecyl sulfate and 27.5%-v/v acetonitrile as separation electrolyte. The separation voltage was -20 kV, UV-detection was at 200 nm, and the acidified concentrate was injected for 36 s at 1 bar (or 72% of the total capillary length, 60 cm). Both purified water and 10-fold diluted waste water exhibited a linear range of two orders of concentration magnitude. The coefficient of determination, and intra- and interday repeatability were 0.991-0.997, 2.5-6.2, and 4.4-9.7%RSD (n=6), respectively, for purified water. The values were 0.991-0.997, 3.4-7.1, and 8.7-9.8%RSD (n=6), correspondingly, for 10-fold diluted waste water. The method detection limit was in the range from 0.04-0.09 to 1.20-6.97 ng/mL for purified and undiluted waste water, respectively.

  6. Thermodynamics of binding of a sulfonamide inhibitor to metal-mutated carbonic anhydrase as studied by affinity capillary electrophoresis. (United States)

    Sato, Yosuke; Hoshino, Hitoshi; Iki, Nobuhiko


    By affinity capillary electrophoresis (ACE), the thermodynamic binding constants of a sulfonamide (SA) inhibitor to bovine carbonic anhydrase II (CA) and metal mutated variants (M-CAs) were evaluated. 1-(4-Aminosulfonylphenylazo)-2-naphthol-6,8-disulfonate was used as the SA in the electrophoretic buffer for ACE. The Scatchard analysis of the dependence of the electrophoretic mobility of native CA on the SA concentration provided the binding constant to be Kb=(2.29±0.05)×10(6) M(-1) (at pH8.4, 25°C). On the other hand, apoCA showed far smaller value [Kb=(3.76±0.14)×10(2) M(-1)], suggesting that the coordination of SA to the Zn(II) center controlled the binding thermodynamics. The ACE of M-CAs showed the same behaviors as native CA but with different Kb values. For example, Co-CA adopting the same tetrahedral coordination geometry as native CA exhibited the largest Kb value [(2.55±0.05)×10(6) M(-1)] among the M-CAs. In contrast, Mn- and Ni-CA, which adopted the octahedral coordination geometry, had Kb values that were about two orders of magnitude lower. Because the hydrophobic cavity of CA around the active center pre-organized the orientation of SA, thereby fixing the ligating NH(-) moiety to the apex of the tetrahedron supported by three basal His3 of CA, metals such as Zn and Co at the center of M-CA gave the most stable CA-SA complex. However, pre-organization was not favored for octahedral geometry. Thus, pre-organization of SA was the key to facilitating the tetrahedral coordination geometry of the Zn(II) active center of CA.

  7. Study on Preparation of Water Soluble Polyester Insulation Electrophoretic Coating by Using Waste Polyester Bottle as Raw Material%废聚酯瓶制取水溶性聚酯绝缘电泳漆的研究

    Institute of Scientific and Technical Information of China (English)

    陈玉滨; 吴津成; 陈文波


    Water soluble polyester resin for insulation electrophoretic coating was prepared by using waste polyester bottle as raw materials and a series of chemical reactions. The influence factors such as catalyst, dosage and kinds of polyol and anhydride on water soluble polyester insulation electrophoretic coating were studied.%采用废聚酯瓶为原材料,经一系列化学反应,制得漆包线用水溶性聚酯绝缘电泳漆树脂。考察了催化剂、多元醇和酸酐的种类及用量对水溶性聚酯绝缘电泳漆的影响。

  8. Sweeping of alprenolol enantiomers with an organic solvent and sulfated β-cyclodextrin in capillary electrophoresis. (United States)

    Rabanes, Heide R; Quirino, Joselito P


    Sweeping, an on-line sample concentration technique in CE, is the picking and accumulation of analytes by the pseudostationary phase or complexing additive. In the presence of an electric field, the analytes concentrated at the additive front that initially penetrated the sample zone. Here, we describe the sweeping of cationic alprenolol enantiomers using sulfated β-CD and organic solvent. The separation solution contained the anionic additive while ACN was in the sample solution. With fused silica capillaries, positive polarity, and solutions buffered at pH 3, the direction of the enantiomers' effective electrophoretic mobility was the same as the electrophoretic mobility (or electrophoretic mobility without additive). When the amount of ACN in the sample was increased (i.e. 60%), the interaction between the analytes and additive became negligible. This caused the sweeping boundary to shift from the electrophoretically moving β-CD front to the zone between the sample and separation solution. The equation that described the narrowing of injected sample zone was derived. The performance of sweeping with 60% ACN in the sample was then studied under different operating conditions (e.g. type of injection, injection time, and CD concentration). The low interaction between enantiomers and additive gave only moderate increases in sensitivity (approximately tenfold), but was improved when field enhancement was used during electrokinetic injection. With a conductivity difference (separation/sample solution) of 70 and a short injection time of 30 s at 20 kV, peak improvements of >100-fold was easily achieved.

  9. Study about the capillary absorption and the sorptivity of concretes with Cuban limestone aggregates


    Howland, J. J.; Martín, A. R.


    The objective of this study was to demonstrate the possibility to obtain concretes in Cuba with values of effective porosity below of 10%, using limestone aggregates with high levels of absorption (higher than 1% in many cases), and values of Sorptivity below of 5 x 10-5 m/s1/2 as is established in the document prepared by the DURAR Latin Working Group, for structures exposed to very aggressive environments. The experimental results showed that the use of the trial method of capillary absorpt...

  10. Exploratory study of temperature oscillations related to transient operation of a Capillary Pumped Loop heat pipe (United States)

    Kiper, A. M.; Swanson, T. D.; Mcintosh, R.


    An analytical study has been conducted for better understanding of a peculiar transient behavior which was displayed in testing of a Capillary Pumped Loop (CPL) heat pipe system. During several test runs of this CPL system varying degrees of surface temperature oscillations occurred in the inlet line of the evaporators. Although several theories have been forwarded to explain this observed phenomenon, a satisfactory understanding of causes of these oscillations is still missing. The present investigation derives the conditions which lead to such oscillatory temperature behavior in evaporator inlet section of the mentioned CPL system. Stability characteristics of these temperature oscillations were investigated.

  11. DNA gel electrophoretic and microaut oradiographic studies on apoptosisin bone tumor cells after exposure with 153Sm-EDTMP

    Institute of Scientific and Technical Information of China (English)


    The apoptosis in bone tumor cells is studied after 153Sm-EDTMP irradiation.Fragmented DNA is analyzed by agarose gel electrophoresis.Experimental observations show that 153Sm-EDTMP exposureinduces the internucleosomal DNA damage in bone tumor cells the DNAladder pattern formation in bone tumor cells is shown.At the same time,the microautoradiographic study indicates that 153153Sm-EDTMP could permeate through cell membrane and displays membrane-seeking condensation in bone tumor cells.Soon afterwards 153Sm-EDTMP could be phagocytized by the tumor cells and distributed in cytoplasm as well as nucleus in the form of phagosome.With the prolongation of observing time, the membrane-bounded apoptotic bodies are observed.

  12. Simulated null-gravity environments as applied to electrophoretic separations of biological species (United States)

    Giannovario, J. A.; Griffin, R. N.


    The scale-up of electrophoretic separations to provide preparative quantities of materials has been hampered by gravity induced convection and sedimentation. The separation of biologically important species may be significantly enhanced by electrophoretic space processing. Simple demonstrations on past space flights have proven some principles. Several techniques have been evolved to study electrophoretic separations where the effects of gravity have been nullified or significantly reduced. These techniques employ mechanical design, density gradients and computer modeling. Utilization of these techniques for ground based studies will yield clues as to which biological species can be considered prime candidates for electrophoretic processing in zero-G.

  13. Separation of Proteins by Electrophoretic Affinity Chromatography

    Institute of Scientific and Technical Information of China (English)

    邺韶骅; 刘铮; 丁富新; 袁乃驹


    A new kind of electrophoretic affinity chromatography (EAC) for bioseparation was proposed,Separation by EAC was conducted in a multicompartment electrolyzer in which the affinity gel media were packed in one of the central compartments.The presence of an electric field accelerated the migration of proteins inside the gel matrix during adsorption and descrption processes,This led to the increase of the overall speed of separation,The present study was focused on the effect of the strength of the electric field on adsorption and desorption processes.

  14. Theoretical study and practical application of the capillary film solar distiller

    Energy Technology Data Exchange (ETDEWEB)

    Bouchekima, Bachir [Universite de Blida, Inst. de Chimie Industrielle, Blida (Algeria); Gros, Bernard [I.U.T. Paul Sabatier, Dept. Genie Chimique, Toulouse, 31 (France); Ouahes, Ramdane [U.S.T.H.B., Lab. de Chimie Solaire, El Alia (Algeria); Diboun, Mostefa [U.S.T.H.B., Inst. de Chimie Industrielle, El Alia (Algeria)


    In the south of Algeria, to supply sufficient fresh water for the population, desalination is necessary because water resources (underground and geothermal) are brackish. This paper presents the theoretical study and the results of experiments carried out with a capillary film multi-effect distiller installed in the south of Algeria (in a village near Touggourt, where the temperature of the groundwater is about 65degC at the source). The name of this device is DIFICAP (DIstiller with a FIlm in CAPillary motion). The aim of our study is to improve the efficiency of this distiller. The research and development of this desalination process is carried out under the following aspects: modelisation of heat and mass transfer, experimentation under direct solar radiation in South Algeria and technical development to aim to optimise the efficiency of this distiller. The theoretical and experimental results show that the efficiency of this distiller increases when the temperature of the brackish water, the intensity of the solar radiation and the number of stages increase. (Author)

  15. A Study of Coherent Radiation Generated in an Ablative Capillary Discharge

    Directory of Open Access Journals (Sweden)

    Jakub Hübner


    Full Text Available Feasible soft-X-ray amplification in the CVI and NVII Balmer transition is investigated in a capillary discharge. The best conditions and parameters for the experimental set-up are found for an ablative capillary. The most optimistic results have shown that the gain would be greater than one, which is the condition for successful ASE (Amplified spontaneous emission in capillary discharges. The capillary discharge evolution is modeled using the NPINCH program, employing a one-dimensional physical model based on MHD equations. The information about the capillary discharge evolution is processed in the FLY, FLYPAPER, FLYSPEC programs, enabling the population to be modeled on specific levels during capillary discharge.

  16. Cobalt complexes as internal standards for capillary zone electrophoresis-mass spectrometry studies in biological inorganic chemistry. (United States)

    Holtkamp, Hannah U; Morrow, Stuart J; Kubanik, Mario; Hartinger, Christian G


    Run-by-run variations are very common in capillary electrophoretic (CE) separations and cause imprecision in both the migration times and the peak areas. This makes peak and kinetic trend identification difficult and error prone. With the aim to identify suitable standards for CE separations which are compatible with the common detectors UV, ESI-MS, and ICP-MS, the Co(III) complexes [Co(en)3]Cl3, [Co(acac)3] and K[Co(EDTA)] were evaluated as internal standards in the reaction of the anticancer drug cisplatin and guanosine 5'-monophosphate as an example of a classical biological inorganic chemistry experiment. These Co(III) chelate complexes were considered for their stability, accessibility, and the low detection limit for Co in ICP-MS. Furthermore, the Co(III) complexes are positively and negatively charged as well as neutral, allowing the detection in different areas of the electropherograms. The background electrolytes were chosen to cover a wide pH range. The compatibility to the separation conditions was dependent on the ligands attached to the Co(III) centers, with only the acetylacetonato (acac) complex being applicable in the pH range 2.8-9.0. Furthermore, because of being charge neutral, this compound could be used as an electroosmotic flow (EOF) marker. In general, employing Co complexes resulted in improved data sets, particularly with regard to the migration times and peak areas, which resulted, for example, in higher linear ranges for the quantification of cisplatin.

  17. Validated Method for the Determination of Piroxicam by Capillary Zone Electrophoresis and Its Application to Tablets

    Directory of Open Access Journals (Sweden)

    Arın Gül Dal


    piroxicam in tablets. The separation of piroxicam was conducted in a fused-silica capillary by using 10 mM borate buffer (pH 9.0 containing 10% (v/v methanol as background electrolyte. The optimum conditions determined were 25 kV for separation voltage and 1 s for injection time. Analysis was carried out with UV detection at 204 nm. Naproxen sodium was used as an internal standard. The method was linear over the range of 0.23–28.79 µg/mL. The accuracy and precision were found to be satisfied within the acceptable limits (<2%. The LOD and LOQ were found to be 0.07 and 0.19 µg/mL, respectively. The method described here was applied to tablet dosage forms and the content of a tablet was found in the limits of USP-24 suggestions. To compare the results of capillary electrophoretic method, UV spectrophotometric method was developed and the difference between two methods was found to be insignificant. The capillary zone electrophoretic method developed in this study is rapid, simple, and suitable for routine analysis of piroxicam in pharmaceutical tablets.

  18. A robust method for iodine status determination in epidemiological studies by capillary electrophoresis. (United States)

    de Macedo, Adriana Nori; Teo, Koon; Mente, Andrew; McQueen, Matthew J; Zeidler, Johannes; Poirier, Paul; Lear, Scott A; Wielgosz, Andy; Britz-McKibbin, Philip


    Iodine deficiency is the most common preventable cause of intellectual disabilities in children. Global health initiatives to ensure optimum nutrition thus require continuous monitoring of population-wide iodine intake as determined by urinary excretion of iodide. Current methods to analyze urinary iodide are limited by complicated sample pretreatment, costly infrastructure, and/or poor selectivity, posing restrictions to large-scale epidemiological studies. We describe a simple yet selective method to analyze iodide in volume-restricted human urine specimens stored in biorepositories by capillary electrophoresis (CE) with UV detection. Excellent selectivity is achieved when using an acidic background electrolyte in conjunction with dynamic complexation via α-cyclodextrin in an unmodified fused-silica capillary under reversed polarity. Sample self-stacking is developed as a novel online sample preconcentration method to boost sensitivity with submicromolar detection limits for iodide (S/N ≈ 3, 0.06 μM) directly in urine. This assay also allows for simultaneous analysis of environmental iodide uptake inhibitors, including thiocyanate and nitrate. Rigorous method validation confirmed good linearity (R(2) = 0.9998), dynamic range (0.20 to 4.0 μM), accuracy (average recovery of 93% at three concentration levels) and precision for reliable iodide determination in pooled urine specimens over 29 days of analysis (RSD = 11%, n = 87).

  19. Numerical study on flow rate limitation of open capillary channel flow through a wedge

    Directory of Open Access Journals (Sweden)

    Ting-Ting Zhang


    Full Text Available The flow characteristics of slender-column flow in wedge-shaped channel under microgravity condition are investigated in this work. The one-dimensional theoretical model is applied to predict the critical flow rate and surface contour of stable flow. However, the one-dimensional model overestimates the critical flow rate for not considering the extra pressure loss. Then, we develop a three-dimensional simulation method with OpenFOAM, a computational fluid dynamics tool, to simulate various phenomena in wedge channels with different lengths. The numerical results are verified with the capillary channel flow experimental data on the International Space Station. We find that the three-dimensional simulation perfectly predicts the critical flow rates and surface contours under various flow conditions. Meanwhile, the general behaviors in subcritical, critical, and supercritical flow are studied in three-dimensional simulation considering variations of flow rate and open channel length. The numerical techniques for three-dimensional simulation is validated for a wide range of configurations and is hopeful to provide valuable guidance for capillary channel flow experiment and efficient liquid management in space.

  20. Human neutrophil elastase inhibition studied by capillary electrophoresis with laser induced fluorescence detection and microscale thermophoresis. (United States)

    Syntia, Fayad; Nehmé, Reine; Claude, Bérengère; Morin, Philippe


    Capillary electrophoresis-laser induced fluorescence (CZE-LIF) and microscale thermophoresis (MST) were used for the first time to study the inhibition of human neutrophil elastase (HNE). We recently studied HNE kinetics (Km and Vmax) by developing an in-capillary CZE-LIF assay based on transverse diffusion of laminar flow profiles (TDLFP) for reactant mixing. In this work, the former assay was adapted to monitor HNE inhibition. Two natural well known HNE inhibitors from the triterpene family, ursolic acid and oleanolic acid, were tested to validate the developed assay. Since the solubility of pentacyclic triterpenes in aqueous media where the enzymatic reaction will take place is limited, the effect of DMSO and ethanol on HNE was studied using microscale thermophoresis (MST). An agglomeration of the enzyme was revealed when preparing the inhibitor in 5% (v/v) DMSO. This phenomenon did not occur in the presence of ethanol. Therefore, ethanol was used as inhibitor solvent, at a limited percentage of 20% (v/v). In these conditions and after optimization of the TDLFP approach, the repeatability (RSD on migration times and peak-areas inferior to 2.2%) of the CZE-LIF assay and the sensitivity (LOQ of few nM) were found to be satisfactory for conducting inhibition assays. IC50 values for ursolic and oleanolic acid were successfully determined. They were respectively equal to 5.62±0.10μM (r(2)=0.9807; n=3) and to 8.21±0.23μM (r(2)=0.9887; n=3). Excellent agreement was found between the results obtained by CE and those reported in literature which validates the developed method. Particularly, the CE-based assay is able to rank HNE inhibitors relative to each other. Furthermore, MST technique was used for evaluating HNE interaction with the ursolic acid. Up to 16 capillaries were automatically processed to obtain in one titration experiment the dissociation constant for the HNE-ursolic acid complex. Ki was found to be 2.72±0.66μM (n=3) which is in excellent agreement

  1. Experimental study of crossover from capillary to viscous fingering for supercritical CO2-water displacement in a homogeneous pore network. (United States)

    Wang, Ying; Zhang, Changyong; Wei, Ning; Oostrom, Mart; Wietsma, Thomas W; Li, Xiaochun; Bonneville, Alain


    Carbon sequestration in saline aquifers involves displacing brine from the pore space by supercritical CO(2) (scCO(2)). The displacement process is considered unstable due to the unfavorable viscosity ratio between the invading scCO(2) and the resident brine. The mechanisms that affect scCO(2)-water displacement under reservoir conditions (41 °C, 9 MPa) were investigated in a homogeneous micromodel. A large range of injection rates, expressed as the dimensionless capillary number (Ca), was studied in two sets of experiments: discontinuous-rate injection, where the micromodel was saturated with water before each injection rate was imposed, and continuous-rate injection, where the rate was increased after quasi-steady conditions were reached for a certain rate. For the discontinuous-rate experiments, capillary fingering and viscous fingering are the dominant mechanisms for low (logCa ≤ -6.61) and high injection rates (logCa ≥ -5.21), respectively. Crossover from capillary to viscous fingering was observed for logCa = -5.91 to -5.21, resulting in a large decrease in scCO(2) saturation. The discontinuous-rate experimental results confirmed the decrease in nonwetting fluid saturation during crossover from capillary to viscous fingering predicted by numerical simulations by Lenormand et al. (J. Fluid Mech.1988, 189, 165-187). Capillary fingering was the dominant mechanism for all injection rates in the continuous-rate experiment, resulting in monotonic increase in scCO(2) saturation.

  2. NMR study comparing capillary trapping in Berea sandstone of air, carbon dioxide, and supercritical carbon dioxide after imbibition of water (United States)

    Prather, Cody A.; Bray, Joshua M.; Seymour, Joseph D.; Codd, Sarah L.


    Nuclear magnetic resonance (NMR) techniques were used to study the capillary trapping mechanisms relevant to carbon sequestration. Capillary trapping is an important mechanism in the initial trapping of supercritical CO2 in the pore structures of deep underground rock formations during the sequestration process. Capillary trapping is considered the most promising trapping option for carbon sequestration. NMR techniques noninvasively monitor the drainage and imbibition of air, CO2, and supercritical CO2 with DI H2O at low capillary numbers in a Berea sandstone rock core under conditions representative of a deep underground saline aquifer. Supercritical CO2 was found to have a lower residual nonwetting (NW) phase saturation than that of air and CO2. Supercritical CO2 behaves differently than gas phase air or CO2 and leads to a reduction in capillary trapping. NMR relaxometry data suggest that the NW phase, i.e., air, CO2, or supercritical CO2, is preferentially trapped in larger pores. This is consistent with snap-off conditions being more favorable in macroscale pores, as NW fluids minimize their contact area with the solid and hence prefer larger pores.

  3. Selective Photo-Initiated Electrophoretic Separator Project (United States)

    National Aeronautics and Space Administration — Physical Optics Corporation (POC) proposes to develop a Selective Photoinitiated Electrophoretic Separator (SPIES) System to address NASA's volatile gas separation...

  4. Capillary electrophoresis as a versatile tool for the bioanalysis of drugs - a review

    NARCIS (Netherlands)

    Boone, CM; Waterval, JCM; Lingeman, H; Ensing, K; Underberg, WJM


    This review article presents an overview of current research on the use of capillary electrophoretic techniques for the analysis of drugs in biological matrices. The principles of capillary electrophoresis and its various separation and detection modes are briefly discussed. Sample pretreatment meth

  5. Conceptual design and sample preparation of electrode covered single glass macro-capillaries for studying the effect of an external electric field on particle guiding

    Energy Technology Data Exchange (ETDEWEB)

    Wartak, A. [Institute of Applied Physics, TU Wien, A-1040 Vienna (Austria); Bereczky, R.J., E-mail: [Institute for Nuclear Research, Hungarian Academy of Sciences (ATOMKI), H-4026 Debrecen, P.O. Box 51 (Hungary); Kowarik, G. [Institute of Applied Physics, TU Wien, A-1040 Vienna (Austria); Tőkési, K. [Institute for Nuclear Research, Hungarian Academy of Sciences (ATOMKI), H-4026 Debrecen, P.O. Box 51 (Hungary); Aumayr, F. [Institute of Applied Physics, TU Wien, A-1040 Vienna (Austria)


    We present the design and construction of a macroscopic glass capillary covered by electrodes on the outside. With these new capillary targets it will be possible to study the influence of an external electric field on the process of guiding of charged particles through a capillary. The new degrees of freedoms will contribute to both a better fundamental understanding of the guiding phenomenon but might also be of use in practical applications.

  6. Study of the operational properties of the Capillary Plasma Electrode (CPE) discharges (United States)

    Lopez, Jose; Jacome, David; Zhu, Wei-Dong; Figus, Margaret; Becker, Kurt H.


    Various approaches have been pursued to create stable atmospheric pressure discharges by extending the lifetime of the diffuse phase of the discharge to hundreds of microseconds. Previous research showed that the stability of the diffuse mode is dependent on the frequency (in the kHz range), gas type power, mode of the excitation, and geometrical confinement. Some of the most promising approaches are based on the recognition of the arc formation in high-pressure plasmas can be avoided and stable high-pressure plasma can be generated and maintained when the plasma are spatially constricted to the dimensions of tens to hundreds of microns. The Capillary Plasma Electrode (CPE) discharge is stable to produce stable atmospheric pressure nonequilibrium plasma. The CPE is similar in design to the Barrier Electrode Discharge, but has perforated dielectrics. The configuration, aside from exhibiting a diffuse mode of operation, also exhibits the so-called ``capillary jet'' mode, in which the capillaries “turn on” and a bright plasma jet emerges from the capillaries. The capillary jets from adjacent capillaries overlap so that the discharge appears uniform when the electrode contains an array of holes. There appears to be a threshold frequency for the capillary jet formation, which is strongly dependent on the L/D ratio of the capillaries, where D is diameter of the capillary and L its length. However, the operating principles and basic properties of this behavior are not well understood. The current work explores these modes of operations of the CPE by characterizing the electrical and optical emission properties of this discharge by examining a multi-hole discharge as well as a single capillary discharge reactor.

  7. Capillary electrophoresis with electrochemiluminescence detection for the analysis of quinolone drugs and pharmacokinetics study

    Institute of Scientific and Technical Information of China (English)

    Yan Ming Liu; Jun Tao Cao; Hui Wang


    A novel method for the determination of two quinolone drugs norfloxacin (NOR) and levofloxacin (LVX) was described by capillary electrophoresis with electrochemiluminescence detection. The good relationship (r ≥ 0.9991) between peak area and concentration of analytes was established over two orders of magnitude. The limits of detection (LOD, S/N = 3) in standard solution are 4.8 × 10-7 mol/L for NOR and 6.4 × 10-7 mol/L for LVX, respectively. The limits of quantitation (LOQ, S/N = 10) in real human urine samples are 1.2 × 10-6 mol/L for NOR and 1.4 × 10-6 mol/L for LVX, respectively. The present method was successfully applied to the determination of NOR and LVX in human urine and the study of pharmacokinetics of NOR.

  8. Experimental study of three-wave interactions among capillary-gravity surface waves

    CERN Document Server

    Haudin, Florence; Deike, Luc; Jamin, Timothée; Falcon, Eric; Berhanu, Michael


    In propagating wave systems, three or four-wave resonant interactions constitute a classical non-linear mechanism exchanging energy between the different scales. Here we investigate three-wave interactions for gravity-capillary surface waves in a closed laboratory tank. We generate two crossing wave-trains and we study their interaction. Using two optical methods, a local one (Laser Doppler Vibrometry) and a spatio-temporal one (Diffusive Light Photography), a third wave of smaller amplitude is detected, verifying the three-wave resonance conditions in frequency and in wavenumber. Furthermore, by focusing on the stationary regime and by taking into account viscous dissipation, we directly estimate the growth rate of the resonant mode. The latter is then compared to the predictions of the weakly non-linear triadic resonance interaction theory. The obtained results confirm qualitatively and extend previous experimental results obtained only for collinear wave-trains. Finally, we discuss the relevance of three-w...

  9. Protein and glycoprotein abnormalities in platelets from human Chediak-Higashi syndrome: polyacrylamide gel electrophoretic study of platelets from five patients. (United States)

    Ledezma, E; Apitz-Castro, R


    Polyacrylamide electrophoretic analysis of proteins and Tritium-labelled glycoproteins of the platelets from five patients with Chediak-Higashi Syndrome shows the existence of marked quantitative differences when compared to normal platelets. While the glycoprotein abnormalities are solely related to the plasma membrane, some of the abnormalities detected in the Coomasie blue pattern are probably representative of defects related to the dense bodies and the alpha-granules. Some of the abnormalities found may, in part, explain the variability of aggregatory responses described in these patients, as well as the marked tendency towards desaggregation exhibited by platelets from humans with the Chediak-Higashi Syndrome.

  10. Separation and analysis of triazine herbcide residues by capillary electrophoresis. (United States)

    Elbashir, Abdalla A; Aboul-Enein, Hassan Y


    Triazines are widely used in agriculture around the world as selective pre- and post-emergence herbicides for the control of broad leaf and grassy weeds. With high toxicity and persistence, triazines can contaminate the environment and crops, so the development of rapid and sensitive methods for the determination of different triazines is necessary. Capillary electrophoresis comprises a group of techniques used to separate chemical mixtures. Analytical separation is based on different electrophoretic mobilities. This review focuses on the analysis of triazine herbicides with different modes of capillary electrophoresis, including capillary zone electrophoresis, micellar electrokinetic capillary electrophoresis, capillary electrochromatography and nonaqueous capillary electrophoresis. Determinations of triazines in various matrices such as surface water, groundwater, vegetables, soil and grains are emphasized.

  11. Predicting Electrophoretic Mobility of Protein-Ligand Complexes for Ligands from DNA-Encoded Libraries of Small Molecules. (United States)

    Bao, Jiayin; Krylova, Svetlana M; Cherney, Leonid T; Hale, Robert L; Belyanskaya, Svetlana L; Chiu, Cynthia H; Shaginian, Alex; Arico-Muendel, Christopher C; Krylov, Sergey N


    Selection of target-binding ligands from DNA-encoded libraries of small molecules (DELSMs) is a rapidly developing approach in drug-lead discovery. Methods of kinetic capillary electrophoresis (KCE) may facilitate highly efficient homogeneous selection of ligands from DELSMs. However, KCE methods require accurate prediction of electrophoretic mobilities of protein-ligand complexes. Such prediction, in turn, requires a theory that would be applicable to DNA tags of different structures used in different DELSMs. Here we present such a theory. It utilizes a model of a globular protein connected, through a single point (small molecule), to a linear DNA tag containing a combination of alternating double-stranded and single-stranded DNA (dsDNA and ssDNA) regions of varying lengths. The theory links the unknown electrophoretic mobility of protein-DNA complex with experimentally determined electrophoretic mobilities of the protein and DNA. Mobility prediction was initially tested by using a protein interacting with 18 ligands of various combinations of dsDNA and ssDNA regions, which mimicked different DELSMs. For all studied ligands, deviation of the predicted mobility from the experimentally determined value was within 11%. Finally, the prediction was tested for two proteins and two ligands with a DNA tag identical to those of DELSM manufactured by GlaxoSmithKline. Deviation between the predicted and experimentally determined mobilities did not exceed 5%. These results confirm the accuracy and robustness of our model, which makes KCE methods one step closer to their practical use in selection of drug leads, and diagnostic probes from DELSMs.

  12. Affinity capillary electrophoresis: the theory of electromigration. (United States)

    Dubský, Pavel; Dvořák, Martin; Ansorge, Martin


    We focus on the state-of-the-art theory of electromigration under single and multiple complexation equilibrium. Only 1:1 complexation stoichiometry is discussed because of its unique status in the field of affinity capillary electrophoresis (ACE). First, we summarize the formulas for the effective mobility in various ACE systems as they appeared since the pioneering days in 1992 up to the most recent theories till 2015. Disturbing phenomena that do not alter the mobility of the analyte directly but cause an unexpected peak broadening have been studied only recently and are also discussed in this paper. Second, we turn our attention to the viscosity effects in ACE. Change in the background electrolyte viscosity is unavoidable in ACE but numerous observations scattered throughout the literature have not been reviewed previously. This leads to an uncritical employment of correction factors that may or may not be appropriate in practice. Finally, we consider the ionic strength effects in ACE, too. Limitations of the current theories are also discussed and the tasks identified where open problems still prevail. Graphical Abstract A weak base (A) undergoes an acidic-basic equilibria (in blue) and migrates with an electrophoretic mobility of [Formula: see text]. Simultaneously, it interacts with a selector (sel) while the analyte-selector complex migrates with an electrophoretic mobility of [Formula: see text]. The strength of the interaction (in orange) is governed by the binding constant, K A , and the concentration of the selector, c sel . This all gives the analyte an effective mobility of [Formula: see text] and moves it out of the zero position (EOF; right top insert). The interaction of the positively charged analyte with the neutral selector slows down the analyte with increasing selector concentration (right bottom insert).

  13. Electrophoretic karyotype of Cercospora kikuchii. (United States)

    Hightower, R C; Callahan, T M; Upchurch, R G


    Classical genetic analyses are not possible with the phytopathogenic fungus Cercospora kikuchii since no sexual stage has been identified. To facilitate gene mapping and to develop an understanding of the genome organization of C. kikuchii, an electrophoretic karyotype has been obtained using contour-clamped homogeneous electric field gel electrophoresis (CHEF). Eight chromosomes, two of which migrate as a doublet, have been separated into seven bands ranging from 2.0 to 5.5 Mb. Using this determination of chromosome number and size, the total genome size of C. kikuchii is estimated to be 28.4 Mb. In addition, genes encoding tubulin, ribosomal DNA, and four previously isolated light-enhanced cDNAs from C. kikuchii were assigned to chromosomes by Southern-hybridization analysis of CHEF blots.

  14. Theoretical Study on the Capillary Force between an Atomic Force Microscope Tip and a Nanoparticle

    Institute of Scientific and Technical Information of China (English)

    LI Zhao-Xia; ZHANG Li-Juan; YI Hou-Hui; FANG Hai-Ping


    @@ Considering that capillary force is one of the most important forces between nanoparticles and atomic force microscope (AFM) tips in ambient atmosphere, we develop an analytic approach on the capillary force between an AFM tip and a nanoparticle. The results show that the capillary forces are considerably affected by the geometry of the AFM tip, the humidity of the environment, the vertical distance between the AFM tip and the nanoparticle, as well as the contact angles of the meniscus with an AFM tip and a nanoparticle. It is found that the sharper the AFM tip, the smaller the capillary force. The analyses and results are expected to be helpful for the quantitative imaging and manipulating of nanoparticles by AFMs.

  15. Experimental Studies on Heat Transfer Characteristics In Inverted Evaporator of Micaro/Miniature Capillary Pumped Loop

    Institute of Scientific and Technical Information of China (English)

    ZhuNing; HouZengqi; 等


    This paperpresents the experimental inverstigation on the heat transfer characteristics in inverted evaporator of Micro/Miniature Capillary Pumped Loop(MCPL).THe evaporation heat transfer coefficients as a function of the heat flux density,the geometrical sizes of capillary wick structure and the vapor grooves are shown.Qualitative analysis of the heat transfer characteristics of the inverted evaporator of MCPL is also made.

  16. Electrophoretic fingerprinting of benzodiazepine tablets in spike drinks. (United States)

    Sáiz, Jorge; Ortega-Ojeda, Fernando; López-Melero, Lucía; Montalvo, Gema; García-Ruiz, Carmen


    Over the last few years, there has been an increase in the reports of drug-facilitated crimes. The list of drugs associated with these crimes is extensive and benzodiazepines constitute one of the groups of substances more commonly used. The sedative properties, which characterize benzodiazepines, are enhanced when such drugs are combined with alcohol, being more attractive for committing these types of crimes. In this work, a capillary electrophoresis method was applied to the analysis of 63 different samples of club drinks spiked with benzodiazepine tablets. The resulting electropherograms were processed and analyzed with the chemometric multivariate techniques: principal component analysis (PCA) and soft independent modeling of class analogies (SIMCA) classification. The PCA results allowed a clear differentiation of each drug class in a 3D plot. In addition, the SIMCA classification model (5% significance level) showed that eight out of nine test samples were automatically assigned by software to their proper sample class. The conflicting sample was correctly classified in the Coomans' plot (95% confidence). This novel approach based on the comparison of electrophoretic profiles of spiked drinks by chemometric tools allows determining the benzodiazepine used for drink spiking without the use of drug standards. Moreover, it provides an opportunity for the forensic laboratories to incorporate the identification capability provided by the electrophoretic fingerprinting of benzodiazepine solutions in existing or new databases.

  17. Optimization of a nano-enzymatic reactor for on-line tryptic digestion of polypeptide conjugates by capillary electrophoresis. (United States)

    Ladner, Yoann; Coussot, Gaelle; Ebner, Stefanie; Ibrahim, Amal; Vidal, Laetitia; Perrin, Catherine


    This work aims at studying the optimization of an on-line capillary electrophoresis (CE)-based tryptic digestion methodology for the analysis of therapeutic polypeptides (PP). With this methodology, a mixture of surrogate peptide fragments and amino acid were produced on-line by trypsin cleavage (enzymatic digestion) and subsequently analyzed using the same capillary. The resulting automation of all steps such as injection, mixing, incubation, separation and detection minimizes the possible errors and saves experimental time. In this paper, we first study the differents parameters influencing PP cleavage inside the capillary (plug length, reactant concentration, incubation time, diffusion and electrophoretic plugs mixing). In a second part, the optimization of the electrophoretic separation conditions of generated hydrolysis products (nature, pH and ionic strength (I) of the background electrolyte (BGE)) is described. Using the optimized conditions, excellent repeatability was obtained in terms of separation (migration times) and proteolysis (number of products from enzymatic hydrolysis and corresponding amounts) demonstrating the robustness of the proposed methodology.

  18. Pulmonary surfactant function studied with the pulsating bubble surfactometer (PBS) and the capillary surfactometer (CS). (United States)

    Enhorning, G


    Two instruments, the pulsating bubble surfactometer (PBS) and the capillary surfactometer (CS), were constructed for a study of pulmonary surfactant's physical properties. The instruments study spherical surfaces as in alveoli (PBS) and cylindrical surfaces as in terminal conducting airways (CS). Phospholipids, pulmonary surfactant's main components, are amphiphilic and, therefore, spontaneously form a film at air-liquid interfaces. When the film in the PBS is compressed to a reduced area during 'expiration', the molecules come closer together. Thereby, a high surface pressure develops, causing surface tension to be reduced more than bubble radius. If these conditions, observed with the PBS are analogous in lungs, alveolar stability would be promoted. The CS was developed for a study of how surfactant has ability to maintain patency of narrow conducting airways. Provided adsorption is extremely fast, a surfactant film will line the terminal conducting airway as soon as liquid blocking the airway has been extruded. During expiration that film will develop high surface pressure (=low surface tension). This will counteract the tendency for liquid to accumulate in the airway's most narrow section. If surfactant is dysfunctioning, liquid is likely to accumulate and block terminal airways. Airway resistance would then increase, causing FEV(1) to be reduced.

  19. Surface modification of titanium dioxide for electrophoretic particles

    Institute of Scientific and Technical Information of China (English)

    PENG Xuhui; LE Yuan; BIAN Shuguang; LI Woyuan; WU Wei; DAI Haitao; CHEN Jianfeng


    To prepare stable electrophoretic ink (E Ink)needs color particles to be uniformly dispersed in the organic medium.Thus,t-he modification of inorganic particle surface is required.In this paper,Titanium dioxide modified by alumina has been studied.The surface composition and structures of modified particles have been characterized by X-ray photoelectron spectrometer (XPS),X-ray diffractometer (XRD) and Fourier transform infrared spectrometer (FT-IR).The dispersibility and electrophoretic mobility of these particles in tetrachloroethylene (TCE) have been investigated by laser particle size analyzer,static sedimentation and electrophoretic instrument.Effects of temperature,pH value and stirring rate on the dispersibility and the charge property of samples have been discussed.The results indicate the settle time of modified TiO2 can last 120 h with the response time of 35 s under the optimized modifying conditions,in which temperature is 85℃-90℃,pH is 8-9 and stirring rate is have been significantly improved,which means that the modified TiO2 is suitable for electrophoretic ink particles.

  20. Sequential alterations in the diameters of capillaries in rabbit skeletal muscle following deep transverse friction - a morphometric study

    Directory of Open Access Journals (Sweden)

    M. A. Gregory


    Full Text Available Objective: The precise mechanisms by which massage promotes repair in injured soft tissue are unknown. Various authorshave attributed the beneficial effects of massage to vasodilation and increased skin and muscle blood flow. The aim of this study was to determine whether deep transverse friction massage (DTF causes capillary vasodilation in untraumatised skeletal muscle. Setting: Academic institution.Interventions: Twelve New Zealand white rabbits were anaesthetised and the left biceps femoris muscle received 10 minutes of DTF. Following treatment, wedge biopsies were taken from the musclewithin 10 minutes of treatment (R1 - 4, 24 hours (R5 - 8 and 6 days(R9 - 12 after treatment. To serve as controls, similar biopsies weretaken from the right biceps femoris of animals. The samples were fixed, dehydrated and embedded in epoxy resin.Transverse sections (1µm of muscle were cut, stained with 1% aqueous alkaline toluidine blue and examined with a light microscope using a 40X objective. Images containing capillaries were captured using an image analyser with SIS software and the cross sectional diameters of at least 60 capillaries were measured from each specimen. Main Outcome Measures: Changes in capillary diameter. Results: The mean capillary diameters in control muscle averaged 4.76 µm. DTF caused a significant immediate increase of 17.3% in cross sectional area (p<0.001, which was not significantly increased by 10.0% after 24 hours (p>0.05. Six days after treatment the cross-sectional area of the treated muscle was 7.6% smaller than the controls. Conclusions: This confirms the contention that DTF stimulates muscle blood flow immediately after treatment and this may account for its beneficial effects in certain conditions. 

  1. A numerical study of capillary and viscous drainage in porous media

    Energy Technology Data Exchange (ETDEWEB)

    Aker, Eyvind


    Fluid flow in porous media is an important field of study in several contexts, for instance oil recovery and hydrology. This thesis concentrates on the flow properties when one fluid displaces another fluid in a network of pores and throats. It considers the scale where individual pores enter the description. A network model is used to simulate the displacement process. The model describes the pores and throats by means of a square lattice of cylindrical tubes. The thesis examines the interplay between the pressure build up in the fluids and the displacement structure during drainage. The network model is also used to study the stabilisation mechanisms when a stable front develops. It is found, neglecting gravity, that the capillary pressure between two points along the front varies almost linearly as a function of height separation in the direction of the displacement. The thesis presents an alternative view on the displacement process based on the observation that nonwetting fluid flows in separate strands along the front where wetting fluid is displaced. Based on numerical simulations, it is concluded that earlier theories that do not include the effect of nonwetting fluid flowing in strands are incompatible with drainage when strands dominate the displacement process.

  2. Impact of capillary conditioning and background electrolyte composition on capillary electrophoresis analysis of prostate specific antigen isoforms. (United States)

    Farina-Gomez, Noemi; Puerta, Angel; Gonzalez, Monica; Diez-Masa, Jose Carlos; de Frutos, Mercedes


    Glycoproteins expressed in the human body can experience modifications as result of pathological situations. Detection of those changes can be useful as disease biomarkers. As a result of these modifications, size and/or electrical charge of the glycoprotein can be altered. Migration in capillary zone electrophoresis (CZE) is governed by the size to charge ratio of the analyte and therefore this separation technique can be used to monitor those modifications. At its turn, the alteration of the electrophoretical pattern of a given glycoprotein could be used as disease biomarker. To this aim, high repeatability for separation of a large number of peaks for a given glycoprotein is desirable. For prostate cancer, new markers are needed to decrease the high number of false positive results provided by the biomarkers currently used in clinics. In this sense, CZE methods for analysis of the several prostate specific antigen (PSA) peaks which this glycoprotein exhibit, called isoforms and containing one or more glycoforms, could be useful to study the PSA pattern as prostate cancer marker. In this study two complementary strategies to achieve both lot-to-lot capillary repeatability and high resolution of a large number of PSA isoforms are developed. Better performance and precision have been obtained for capillaries conditioned with HCl than for those conditioned with NaOH. Optimization of the background electrolyte (BGE) pH value to 8.0 and inclusion of 3M urea on its composition were the two factors of highest impact for enhancing resolution of the highest number of PSA peaks. Under the optimized conditions for capillary conditioning and BGE pH and composition, long-term resolution of 10 isoforms of PSA was achieved. Inter-day (n=3) %RSD was 0.55 for the ratio tm/tEOF, 1.15 for μeff, and 5.02 for % Acorr of the PSA peaks.

  3. Capillary origami


    Py, Charlotte; Reverdy, Paul; Doppler, L.; J. Bico; Roman, B.; Baroud, Charles,


    International audience; The hairs of a wet dog rushing out from a pond assemble into bundles; this is a common example of the effect of capillary forces on flexible structures. From a practical point of the deformation and adhesion of compliant structures induced by interfacial forces may lead to disastrous effects in mechanical microsystems.

  4. Polyacrylamide medium for the electrophoretic separation of biomolecules (United States)

    Madabhushi, Ramakrishna S.; Gammon, Stuart A.


    A polyacryalmide medium for the electrophoretic separation of biomolecules. The polyacryalmide medium comprises high molecular weight polyacrylamides (PAAm) having a viscosity average molecular weight (M.sub.v) of about 675-725 kDa were synthesized by conventional red-ox polymerization technique. Using this separation medium, capillary electrophoresis of BigDye DNA sequencing standard was performed. A single base resolution of .about.725 bases was achieved in .about.60 minute in a non-covalently coated capillary of 50 .mu.m i.d., 40 cm effective length, and a filed of 160 V/cm at C. The resolution achieved with this formulation to separate DNA under identical conditions is much superior (725 bases vs. 625 bases) and faster (60 min. vs. 75 min.) to the commercially available PAAm, such as supplied by Amersham. The formulation method employed here to synthesize PAAm is straight-forward, simple and does not require cumbersome methods such as emulsion polymerizaiton in order to achieve very high molecular weights. Also, the formulation here does not require separation of PAAm from the reaction mixture prior to reconstituting the polymer to a final concentration. Furthermore, the formulation here is prepared from a single average mol. wt. PAAm as opposed to the mixture of two different average mo. wt. PAAm previously required to achieve high resolution.

  5. Understanding local forces in electrophoretic ink systems: utilizing optical tweezers to explore electrophoretic display devices (United States)

    Wei, David L.; Dickinson, Mark R.; Smith, N.; Gleeson, Helen F.


    Optical tweezers can be used as a valuable tool to characterize electrophoretic display (EPD) systems. EPDs are ubiquitous with e-readers and are becoming a commonplace technology where reflective, low-power displays are required; yet the physics of some features crucial to their operation remains poorly defined. We utilize optical tweezers as a tool to understand the motion of charged ink particles within the devices and show that the response of optically trapped electrophoretic particles can be used to characterize electric fields within these devices. This technique for mapping the force can be compared to simulations of the electric field in our devices, thus demonstrating that the electric field itself is the sole governor of the particle motion in an individual-particle regime. By studying the individual-particle response to the electric field, we can then begin to characterize particle motion in `real' systems with many particles. Combining optical tweezing with particle tracking techniques, we can investigate deviations in many particle systems from the single-particle case.

  6. Application of capillary electrophoresis to the development and evaluation of aptamer affinity probes (United States)

    Sooter, Letha J.; McMasters, Sun; Stratis-Cullum, Dimitra N.


    Nucleic acid aptamers can exhibit high binding affinities for a wide variety of targets and have received much attention as molecular recognition elements for enhanced biosensor performance. These aptamers recognize target molecules through a combination of conformational dependent non-covalent interactions in aqueous media which can be investigated using capillary electrophoresis-based methods. In this paper we report on the results of our studies of the relative binding affinity of Campylobacter jejuni aptamers using a capillary electrophoretic immunoassay. Our results show preferential binding to C. jejuni over other common food pathogen bacteria. Capillary electrophoresis can also be used to develop new aptamer recognition elements using an in vitro selection process known as systematic evolution of ligand by exponential enrichment (SELEX). Recently, this process has been adapted to use capillary electrophoresis in an attempt to shorten the overall selection process. This smart selection of nucleic acid aptamers from a large diversity of a combinatorial DNA library is under optimization for the development of aptamers which bind to Army-relevant targets. This paper will include a discussion of the establishment of CE-SELEX methods for the future development of smart aptamer probes.

  7. Study of Oxidation of Glutathione Treated with Hypochlorous Acid by Capillary Electrophoresis

    Institute of Scientific and Technical Information of China (English)


    Capillary electrophoresis (CE) method was developed for the separation and quantification of reduced glutathione (GSH), oxidized glutathione (GSSG) and glutathione sulphonic acid (GSO3H). Baseline separation was obtained within five minutes. The effects of reaction time and molar ratio of hypochlorous acid (HOCI) to GSH on the oxidation of GSH were investigated.

  8. Study of the electroosmotic flow as a means to propel the mobile phase in capillary electrochromatography in view of further miniaturization of capillary electrochromatography systems. (United States)

    Szekely, Laszlo; Freitag, Ruth


    In this paper, we investigate the phenomenon of electroosmosis as a means to propel a mobile phase, in particular in view of an application in microfluidic systems, which are characterized by significantly smaller volumes of the reservoirs and the separation channels compared to conventional instrumentation. In the microfluidic chip, pH changes due to water electrolysis quickly showed an effect on the electroosmotic flow (EOF), which could be counteracted by either regularly exchanging or buffering the mobile phase. Surface treatment was of no effect in regard to EOF stabilization in empty channels but may have an influence in channels filled with a charged monolith. In fused-silica capillaries the EOF was generally found to decrease from 'naked' to surface-treated to monolith-filled capillaries. The EOF tended to be higher when an organic solvent (acetonitrile) was added to the mobile phase and could be further increased by substituting the water with equal amounts of methanol. In addition, the hydrostatic pressure exerted by the EOF was investigated. In a microfluidic chip with empty (cross-)channels such an effect could be responsible for a redirection of the flow. In capillaries partially filled with a noncharged (non-EOF-generating) monolith, a linear relationship could be established between the EOF created in the empty section of the capillary (apparent mobility) and the length of the monolith (backpressure). In capillaries partially filled with a charged (EOF-producing) monolith, flow inhomogeneities must be expected as a consequence of a superimposition of hydrodynamic pressure and EOF as mobile phase driving force.

  9. Simulations of Electrophoretic RNA Transport Through Transmembrane Carbon Nanotubes


    Zimmerli, Urs; Koumoutsakos, Petros


    The study of interactions between carbon nanotubes and cellular components, such as membranes and biomolecules, is fundamental for the rational design of nanodevices interfacing with biological systems. In this work, we use molecular dynamics simulations to study the electrophoretic transport of RNA through carbon nanotubes embedded in membranes. Decorated and naked carbon nanotubes are inserted into a dodecane membrane and a dimyristoylphosphatidylcholine lipid bilayer, and the system is sub...

  10. Ion guiding in alumina capillaries

    DEFF Research Database (Denmark)

    Juhász, Z.; Sulik, B.; Biri, S.;


    Transmission of a few keV impact energy Ne ions through capillaries in anodic alumina membranes has been studied with different ion counting methods using an energy dispersive electrostatic spectrometer, a multichannel plate (MCP) array and sensitive current-measurement. In the present work, we...... focus our attention to the measurements with the MCP array. The alumina capillaries were prepared by electro-chemical oxidation of aluminium foils. For the present experiments guiding of 3-6 keV Ne ions has been studied in two samples with capillary diameter of about 140 nm and 260 nm and with capillary...... length of about 15 μm. At these energies, the ions have been efficiently guided by the capillaries up to few degrees tilt angle. In this work, we compare the results obtained by the energy dispersive spectrometer to those studied by the MCP array. © 2008 Elsevier B.V. All rights reserved....

  11. Determination of acidity constants of enolisable compounds by capillary electrophoresis. (United States)

    Mofaddel, N; Bar, N; Villemin, D; Desbène, P L


    Research on the structure-activity relationships of molecules with acidic carbon atoms led us to undertake a feasibility study on the determination of their acidity constants by capillary electrophoresis (CE). The studied molecules had diverse structures and were tetronic acid, acetylacetone, diethylmalonate, Meldrum's acid, 3-methylrhodanine, nitroacetic acid ethyl ester, pyrimidine-2,4,6-trione, 3-oxo-3-phenylpropionic acid ethyl ester, 1-phenylbutan-1,3-dione, 5,5-dimethylcyclohexan-1,3-dione and homophthalic anhydride. The p Ka range explored by CE was therefore very large (from 3 to 12) and p Ka values near 12 were evaluated by mathematical extrapolations. The analyses were carried out in CZE mode using a fused silica capillary grafted (or not) with hexadimethrine. Owing to the electrophoretic behaviour of these compounds according to the pH, their acidity constants could be evaluated and appeared in perfect agreement with the literature data obtained, a few decades ago, by means of potentiometry, spectrometry or conductimetry. The p Ka of homophthalic anhydride and 3-methylrhodanine were evaluated for the first time.

  12. Surface initiated polymerization of a cationic monomer on inner surfaces of silica capillaries: analyte separation by capillary electrophoresis versus polyelectrolyte behavior. (United States)

    Witos, Joanna; Karesoja, Mikko; Karjalainen, Erno; Tenhu, Heikki; Riekkola, Marja-Liisa


    [2-(Methacryloyl)oxyethyl]trimethylammonium chloride was successfully polymerized by surface-initiated atom transfer radical polymerization method on the inner surface of fused-silica capillaries resulting in a covalently bound poly([2-(methacryloyl)oxyethyl]trimethylammonium chloride) coating. The coated capillaries provided in capillary electrophoresis an excellent run-to-run repeatability, capillary-to-capillary and day-to-day reproducibility. The capillaries worked reliably over 1 month with EOF repeatability below 0.5%. The positively charged coated capillaries were successfully applied to the capillary electrophoretic separation of three standard proteins and five β-blockers with the separation efficiencies ranging from 132,000 to 303,000 plates/m, and from 82,000 to 189,000 plates/m, respectively. In addition, challenging high- and low-density lipoprotein particles could be separated. The hydrodynamic sizes of free polymer chains in buffers used in the capillary electrophoretic experiments were measured for the characterization of the coatings.

  13. A study on accumulation of magnetic drug in the capillary vessel of target organ using superconducting MDDS (United States)

    Mishima, F.; Akiyama, Y.; Nishijima, S.


    Magnetic Drug Delivery System (MDDS) is one of the drug therapy technologies to accumulate the drug at the targeted part efficiently. The ferromagnetic particle is attached to the medicine, antibody, hormones and so on. The magnetic seeded drug is injected into the blood vessel, and then is accumulated in capillary vessel of target organ by magnetic field generated by the superconducting magnet placed outside of the body. The technology is great prospective for not only human medical treatment but also stockbreeding field. Treatment for cow ovarian diseases (decay of ovarian hormone secretion) requires an improvement in suppression of the drug diffusion to non-diseased part by the blood flow. In order to solve the problem, the applicability of the MDDS was examined. The behavior of the magnetic drug under the magnetic field generated by high temperature superconducting (HTS) bulk magnet were studied by the model experiment and computer simulation with the capillary model of the corpus luteum. As a result, it was shown that MDDS is able to apply to the capillaries of the corpus luteum (yellow body).

  14. A novel QSPR study of normalized migration time for drugs in capillary electrophoresis by new descriptors: quantum chemical investigation. (United States)

    Riahi, Siavash; Beheshti, Abolghasem; Ganjali, Mohammad Reza; Norouzi, Parviz


    Some drugs' migration time (MT) has been studied employing quantitative structure-property relationship using new descriptors that are able to predict MT value with high accuracy. MT property modeling of the drugs was established as a function of the new theoretically derived descriptors applying multiple linear regressions and partial least-squares regression. The genetic algorithm was used to select those variables that resulted in the best-fitted models. To select a set of descriptors that are most relevant to MT, illustrating the affecting degree for the affinity of different descriptors, the linear models with 1-14 variables were constructed and were then investigated based on F-value, squared regression coefficients of cross-validated (Q2), adjusted R2 (R2adj) and standard error of estimate (S) statistical parameters. Finally, the best model with ten variables was selected. Statistical parameters of the test set, such as standard deviation error in test, were 0.559 and 0.616, while relative error of test was equal to 7.648 and 8.497% for multiple linear regressions and partial least-squares models, respectively, confirming the good predictive ability of the model. Since the capillary lengths were not the same for the drugs in the data set, MT values were normalized based on a specific capillary before modeling, which is also one of the advantages of this method, enabling us to use the model for different capillary lengths.

  15. Biologically driven neural platform invoking parallel electrophoretic separation and urinary metabolite screening. (United States)

    Page, Tessa; Nguyen, Huong Thi Huynh; Hilts, Lindsey; Ramos, Lorena; Hanrahan, Grady


    This work reveals a computational framework for parallel electrophoretic separation of complex biological macromolecules and model urinary metabolites. More specifically, the implementation of a particle swarm optimization (PSO) algorithm on a neural network platform for multiparameter optimization of multiplexed 24-capillary electrophoresis technology with UV detection is highlighted. Two experimental systems were examined: (1) separation of purified rabbit metallothioneins and (2) separation of model toluene urinary metabolites and selected organic acids. Results proved superior to the use of neural networks employing standard back propagation when examining training error, fitting response, and predictive abilities. Simulation runs were obtained as a result of metaheuristic examination of the global search space with experimental responses in good agreement with predicted values. Full separation of selected analytes was realized after employing optimal model conditions. This framework provides guidance for the application of metaheuristic computational tools to aid in future studies involving parallel chemical separation and screening. Adaptable pseudo-code is provided to enable users of varied software packages and modeling framework to implement the PSO algorithm for their desired use.

  16. In-capillary derivatization and capillary electrophoresis separation of amino acid neurotransmitters from brain microdialysis samples. (United States)

    Denoroy, Luc; Parrot, Sandrine; Renaud, Louis; Renaud, Bernard; Zimmer, Luc


    A new in-capillary derivatization method with naphtalene-2,3-dicarboxyaldehyde (NDA)/CN(-) has been developed for capillary electrophoresis with laser-induced fluorescence detection of brain microdialysate amino acids. Samples are sandwiched between two plugs of reagent mixture at the capillary inlet and subsequently separated. Highest derivatization yields are obtained by using a reagent to sample plug length ratio equal to 4, performing a first electrophoretic mixing followed by a zero potential amplification step before applying the separation voltage and using a NaCN to NDA concentration ratio equal to 1. This new single-step methodology allows the analysis of amino acid neurotransmitters in rat brain microdialysis samples.

  17. Electrophoretic mobilities of erythrocytes in various buffers (United States)

    Plank, L. D.; Kunze, M. E.; Todd, P. W.


    The calibration of space flight equipment depends on a source of standard test particles, this test particle of choice is the fixed erythrocyte. Erythrocytes from different species have different electrophoretic mobilities. Electrophoretic mobility depends upon zeta potential, which, in turn depends upon ionic strength. Zeta potential decreases with increasing ionic strength, so cells have high electrophoretic mobility in space electrophoresis buffers than in typical physiological buffers. The electrophoretic mobilities of fixed human, rat, and rabbit erythrocytes in 0.145 M salt and buffers of varying ionic strength, temperature, and composition, to assess the effects of some of the unique combinations used in space buffers were characterized. Several effects were assessed: glycerol or DMSO (dimethylsulfoxide) were considered for use as cryoprotectants. The effect of these substances on erythrocyte electrophoretic mobility was examined. The choice of buffer depended upon cell mobility. Primary experiments with kidney cells established the choice of buffer and cryoprotectant. A nonstandard temperature of EPM in the suitable buffer was determined. A loss of ionic strength control occurs in the course of preparing columns for flight, the effects of small increases in ionic strength over the expected low values need to be evaluated.

  18. 12-Channel Peltier array temperature control unit for single molecule enzymology studies using capillary electrophoresis. (United States)

    Craig, Douglas B; Reinfelds, Gundars; Henderson, Anna


    Capillary electrophoresis has been used to demonstrate that individual molecules of a given enzyme support different catalytic rates. In order to determine how rate varies with temperature, and determine activation energies for individual β-galactosidase molecules, a 12-channel Peltier array temperature control device was constructed where the temperature of each cell was separately controlled. This array was used to control the temperature of the central 30 cm of a 50 cm long capillary, producing a temperature gradient along its length. Continuous flow single β-galactosidase molecule assays were performed allowing measurement of the catalytic rates at different temperatures. Arrhenius plots were produced and the distribution of activation energies for individual β-galactosidase molecules was found to be 56 ± 10 kJ/mol with a range of 34-72 kJ/mol.

  19. Chromatographic and electrophoretic methods for nanodisc purification and analysis

    DEFF Research Database (Denmark)

    Justesen, Bo Højen; Günther-Pomorski, Thomas


    Soluble nanoscale lipid bilayers, termed nanodiscs, are widely used in science for studying the membrane-anchored and integral membrane protein complexes under defined experimental conditions. Although their formation occurs by a self-assembly process, nanodisc purification and the verification...... of proper reconstitution are still major challenges during the sample preparation. This review gives an overview of the methods used for purifying and analyzing nanodiscs and nanodisc-reconstituted membrane proteins, with an emphasis on the chromatographic and electrophoretic approaches....

  20. A numerical study on parasitic capillary waves using unsteady conformal mapping (United States)

    Murashige, Sunao; Choi, Wooyoung


    This paper describes fully nonlinear computation of unsteady motion of parasitic capillary waves that appear on the front face of steep gravity waves progressing on water of infinite depth, within the framework of irrotational plane flow. As an alternative to the widely-used boundary integral method with mixed-Eulerian-Lagrangian (MEL) time updating, we focus on a numerical method based on unsteady conformal mapping, which will be hereafter referred to as the unsteady hodograph transformation (UHT) method. In this method, we solve the nonlinear evolution equations to find an unsteady conformal map in a complex plane with which the flow domain is mapped onto the unit disk while the free surface is fixed on the unit circle. The aim of this work is to compare the UHT method with the MEL method and find a more efficient method to compute parasitic capillary waves. From linear stability analysis, it is found that a critical difference between these two methods arises from the kernel of cotangent function in singular integrals, and the UHT method can avoid some numerical instability due to it. Numerical examples demonstrate that the UHT method is more suitable than the MEL method for not only parasitic capillary waves, but also capillary dominated waves. In particular, the UHT method requires no artificial techniques, such as filtering, to control numerical errors, in these examples. In addition, another major difference between the two methods is observed in terms of the clustering property of sample points on the free surface, depending on the restoring force of waves (gravity or surface tension).

  1. Preparation of Panel and Charged Particles for Electrophoretic Display (United States)

    Choi, Hyung Suk; Park, Jin Woo; Park, Lee Soon; Lee, Jung Kyung; Han, Yoon Soo; Kwon, Younghwan

    Studies on the formulation of photosensitive paste for transparent soft mold press (TSMP) method have been performed. With the optimum formulation of the photosensitive paste the box-type barrier rib with good flexibility and high solvent resistance was fabricated, suitable for the panel material of the electrophoretic display. Cationically-charged white particles were prepared by using TiO2 nanoparticles, silane coupling agent with amino groups, dispersant and acetic acid. The cationically charged TiO2 particles exhibited 74.09 mV of zeta potential and 3.11 × 10-5 cm2/Vs of mobility. Electrophoretic display fabricated with the charged TiO2 particles exhibited 10 V of low driving voltage and maximum contrast ratio (5.3/1) at 30 V.

  2. Study about the capillary absorption and the sorptivity of concretes with Cuban limestone aggregates

    Directory of Open Access Journals (Sweden)

    Howland, J. J.


    Full Text Available The objective of this study was to demonstrate the possibility to obtain concretes in Cuba with values of effective porosity below of 10%, using limestone aggregates with high levels of absorption (higher than 1% in many cases, and values of Sorptivity below of 5 x 10-5 m/s1/2 as is established in the document prepared by the DURAR Latin Working Group, for structures exposed to very aggressive environments. The experimental results showed that the use of the trial method of capillary absorption of Göran Fagerlund, were obtained concretes with effective porosity below of the 10%, for water/cement ratios of 0.4 and 0.45, but the values of sorptivities were very high. Nevertheless the subsequent use of the trial method of the ASTM C1585, that use cylinders probes with bigger depth and different processing, permits to obtain the desired sorptivity values for water/cement ratios of 0.4 and 0.45 whenever would be fulfilled the Good Practices of the Construction.El objetivo del estudio fue demostrar la posibilidad de lograr en Cuba, con el empleo de áridos calizos de elevada absorción (mayores del 1% en muchos casos, hormigones con valores de porosidad efectiva inferiores al 10% y de velocidad de absorción capilar (Sorptividad inferiores a 5 x 10-5 m/s1/2, tal como establece el documento elaborado por la RED DURAR del CYTED para estructuras expuestas a ambientes muy agresivos. Los resultados experimentales mostraron que con la aplicación del método de ensayo de absorción capilar de Göran Fagerlund se obtuvieron porosidades efectivas inferiores al 10% para relaciones agua/cemento de 0,4 y 0,45, pero los valores de sorptividad fueron muy elevados. No obstante la aplicación posterior del método de ensayo de la ASTM C1585 que utiliza probetas de mayor espesor y diferente tratamiento, permitió obtener los valores indicados de sorptividad para relaciones agua/cemento de 0,4; 0,45 siempre que se cumplan las Buenas Prácticas constructivas.

  3. Capillary ion electrophoresis of inorganic anions and uric acid in human saliva using a polyvinyl alcohol coated capillary column and hexamethonium chloride as additive of background electrolyte. (United States)

    Mori, Masanobu; Yamamoto, Tsukasa; Kaseda, Maki; Yamada, Sachiko; Itabashi, Hideyuki


    A combination of polyvinyl alcohol chemically coated capillary (PVA capillary) and background electrolyte (BGE) with ion-pair reagent (hexamethonium dichloride, HMC) was used on capillary ion electrophoresis-UV detection (CIE-UV) for analysis of Br⁻, I⁻, NO₂⁻, NO₃⁻, SCN⁻ and uric acid in human saliva. The PVA capillary prepared in our laboratory minimized electro-osmotic flow (EOF) at the BGE in pH 3-10, and did not affect the UV detection at 210 nm by the PVA-layer on capillary wall. Therefore, use of the PVA capillary was suitable for sensitive UV detection for analyte anions, as well as suppression of protein adsorption. In this study, we optimized the BGE of 10 mM phosphate plus 10 mM HMC with applying a voltage of -15 kV. HMC as an additive to BGE could manipulate the electrophoretic mobility of anions, without electrostatic adsorption to the PVA capillary. The CIE-UV could separate and determine analyte anions in human saliva containing proteins by the direct injection without pretreatments such as dilution or deproteinization within 13 min. The relative standard deviations (n=10) were ranged of 0.5-1.6% in migration times, 2.2-6.8% in peak heights and 2.8-8.4% in peak areas. The limits of detection (S/N=3) were ranged of 3.42-6.87 μM. The peak height of anions in this system was gradually decreased through the successive injections of saliva samples, but the problem was successfully solved by periodically conditioning the PVA capillary. The quantifiability of anions in human saliva samples by the CIE-UV was evaluated through the recoveries by standard addition methods and comparison of other representative analytical methods, as well as identification by ion chromatography (IC). From the anion analyses in 12 different saliva samples, the CIE-UV demonstrated that can obtain obvious differences in concentrations of SCN⁻ between of smoker and non-smoker and those of uric acid between male and female with satisfactory results.

  4. Electrophoretic karyotypes of some related Mucor species. (United States)

    Nagy, A; Palagyi, Z; Vastag, M; Ferenczy, L; Vágvölgyi, C


    Contour clamped homogeneous electric field (CHEF) gel electrophoresis was used to obtain electrophoretic karyotypes from nine Mucor strains representing five different species (M. bainieri, M. circinelloides, M. mucedo, M. plumbeus and M. racemosus). The chromosomal banding patterns revealed high variability among the isolates. The sizes of the DNA in the Mucor chromosomes were estimated to be between 2.5 and 8.7 Mb. The total genome sizes were calculated to be between 30.0 and 44.7 Mb. The applicability of these electrophoretic karyotypes for the investigation of genome structure, for strain identification and for species delimitation is considered.

  5. Gold nanoparticles deposited capillaries for in-capillary microextraction capillary zone electrophoresis of monohydroxy-polycyclic aromatic hydrocarbons. (United States)

    Wang, Huiyong; Knobel, Gaston; Wilson, Walter B; Calimag-Williams, Korina; Campiglia, Andres D


    This article presents the first application of gold nanoparticles deposited capillaries as pre-concentration devices for in-capillary microextraction CZE and their use for the analysis of monohydroxy-polycyclic aromatic hydrocarbons in synthetic urine samples. The successful separation of 1-hydroxypyrene, 9-hydroxyphenanthrene, 3-hydroxybenzo[a]pyrene (3-OHbap), 4-hydroxybenzo[a]pyrene and 5-hydroxybenzo[a]pyrene under a single set of electrophoretic conditions is demonstrated as well as the feasibility to obtain competitive ultraviolet absorption LOD with commercial instrumentation. Enrichment factors ranging from 87 (9-OHphe) to 100 (3-OHbap) made it possible to obtain LOD ranging from 9 ng/mL (9-OHphe and 3-OHbap) to 14 ng/mL (4-hydroxybenzo[a]pyrene).

  6. Critical Capillary Number of Interfacial Film Displacement in a Capillary Tube

    CERN Document Server

    Yan, Changfei


    The role of surface tension and wettability in the dynamics of air-liquid interfaces during immiscible fluid displacement flows in capillary tube driven by pressure has been investigated. The contact angle and capillary number drive the force wetting processes which is controlled by the balance between the capillary and the viscous lubrication forces. The dynamic wetting condition with the critical capillary number is studied analytically and validated experimentally, which demonstrates that the critical capillary number is associated with the contact angle, slip length and capillary radius.

  7. Numerical Model of Capillary Tubes: Enhanced Performance and Study of Non-Adiabatic Effects


    Ablanque, Nicolas; Oliet, Carles; Rigola, Joaquim; Pérez-Segarra, Carlos David


    In this work a numerical model to simulate the thermal and fluid-dynamic phenomena inside non-adiabatic capillary tubes is presented. The model presented herein is an improved version of the distributed model detailed in [1]. It is based on a pseudo-homogeneous two-phase flow model where the governing equations (continuity, momentum, energy and entropy) are integrated over the discretized fluid domain and solved by means of a step-by-step scheme. The main novelty of the improved algorithm is ...

  8. Studies of Active Ingredients in Cough Syrup by Capillary Zone Electrophoresis with Amperometric Detection

    Institute of Scientific and Technical Information of China (English)

    ZHOU Tian-shu; WANG Ai-fang; WU Fang; SHI Guo-yue; FANG Yu-zhi


    The present paper covers a simple, reliable and reproducible method, based on capillary zone electrophoresis(CZE) with amperometric detection(AD), for the separation and the determination of ephedrine hydrochloride, promethazine hydrochloride and codeine phosphate. Under the optimal conditions, the three analytes were base-line separated completely within 16 min. Good linear relationships between the peak heights and the concentrations of the three analytes were obtained with the correlation coefficients better than 0.9993. The method was directly applied to the determination of the active ingredients in pharmaceutical preparations and the assay results were satisfactory.

  9. Study on Rhizoma Chuanxiong based on capillary electrophoresis with amperometric detection

    Institute of Scientific and Technical Information of China (English)


    A high-performance capillary electrophoresis with amperometric detection(CE-AD) method has been developed for the analysis of seven bioactive ingredients,namely ferulic acid(FA),vanillin,vanillic acid,p-hydroxybenzoic acid,caffeic acid,gallic acid and protocatechuic acid,in Rhizoma Chuanxiong.The effects of several factors such as the acidity and concentration of running buffer,the separation voltage,the applied potential to working electrode and the injection time were investigated.Under the optimum con...

  10. Use of Capillary Electrophoresis in the Study of Interaction between dsDNA and Drug Molecules

    Institute of Scientific and Technical Information of China (English)


    Two 17-mer dsDNA with different sequence characteristics were designed to investigate the binding characteristics of berberine, an anticancer drug with uncertain binding mode, and Hoechst 33258, a model DNA minor groove binder, with dsDNA, respectively by the capillary zone electrophoresis (CZE). Kenndler model analysis revealed that Hoechst 33258 exhibited intermediate affinity with dsDNA, while there was only low affinity and some weak binding preference for AATT-containing to GGCC-containing dsDNA for berberine.

  11. Theory of Cast Formation in Electrophoretic Deposition

    NARCIS (Netherlands)

    Biesheuvel, P. Maarten; Verweij, Henk


    The rate of cast formation in electrophoretic deposition is described by a combination of the equation of continuity for the suspension phase with expressions for the particle velocity and the movement of the cast-suspension boundary. The assumptions necessary to arrive at the well-known equations o

  12. Angiotensin-converting enzyme inhibition studies by natural leech inhibitors by capillary electrophoresis and competition assay. (United States)

    Deloffre, Laurence; Sautiere, Pierre-Eric; Huybrechts, Roger; Hens, Korneel; Vieau, Didier; Salzet, Michel


    A protocol to follow the processing of angiotensin I into angiotensin II by rabbit angiotensin-converting enzyme (ACE) and its inhibition by a novel natural antagonist, the leech osmoregulator factor (LORF) using capillary zonal electrophoresis is described. The experiment was carried out using the Beckman PACE system and steps were taken to determine (a) the migration profiles of angiotensin and its yielded peptides, (b) the minimal amount of angiotensin II detected, (c) the use of different electrolytes and (d) the concentration of inhibitor. We demonstrated that LORF (IPEPYVWD), a neuropeptide previously found in leech brain, is able to inhibit rabbit ACE with an IC(50) of 19.8 micro m. Interestingly, its cleavage product, IPEP exhibits an IC(50) of 11.5 micro m. A competition assay using p-benzoylglycylglycylglycine and insect ACE established that LORF and IPEP fragments are natural inhibitors for invertebrate ACE. Fifty-four percent of insect ACE activity is inhibited with 50 micro m IPEP and 35% inhibition with LORF (25 mm). Extending the peptide at both N- and C-terminus (GWEIPEPYVWDES) and the cleavage of IPEP in IP abolished the inhibitory activity of both peptides. Immunocytochemical data obtained with antisera raised against LORF and leech ACE showed a colocalization between the enzyme and its inhibitor in the same neurons. These results showed that capillary zonal electrophoresis is a useful technique for following enzymatic processes with small amounts of products and constitutes the first evidence of a natural ACE inhibitor in invertebrates.

  13. Multi-Site N-glycan mapping study 1: Capillary electrophoresis – laser induced fluorescence (United States)

    Szekrényes, Ákos; Park, SungAe Suhr; Santos, Marcia; Lew, Clarence; Jones, Aled; Haxo, Ted; Kimzey, Michael; Pourkaveh, Shiva; Szabó, Zoltán; Sosic, Zoran; Feng, Peng; Váradi, Csaba; de l'Escaille, François; Falmagne, Jean-Bernard; Sejwal, Preeti; Niedringhaus, Thomas; Michels, David; Freckleton, Gordon; Hamm, Melissa; Manuilov, Anastasiya; Schwartz, Melissa; Luo, Jiann-Kae; van Dyck, Jonathan; Leung, Pui-King; Olajos, Marcell; Gu, Yingmei; Gao, Kai; Wang, Wenbo; Wegstein, Jo; Tep, Samnang; Guttman, András


    An international team that included 20 independent laboratories from biopharmaceutical companies, universities, analytical contract laboratories and national authorities in the United States, Europe and Asia was formed to evaluate the reproducibility of sample preparation and analysis of N-glycans using capillary electrophoresis of 8-aminopyrene-1,3,6-trisulfonic acid (APTS)-labeled glycans with laser induced fluorescence (CE-LIF) detection (16 sites) and ultra high-performance liquid chromatography (UHPLC, 12 sites; results to be reported in a subsequent publication). All participants used the same lot of chemicals, samples, reagents, and columns/capillaries to run their assays. Migration time, peak area and peak area percent values were determined for all peaks with >0.1% peak area. Our results demonstrated low variability and high reproducibility, both, within any given site as well across all sites, which indicates that a standard N-glycan analysis platform appropriate for general use (clone selection, process development, lot release, etc.) within the industry can be established. PMID:26466659

  14. Raman spectroscopy and capillary electrophoresis applied to forensic colour inkjet printer inks analysis. (United States)

    Król, Małgorzata; Karoly, Agnes; Kościelniak, Paweł


    Forensic laboratories are increasingly engaged in the examination of fraudulent documents, and what is important, in many cases these are inkjet-printed documents. That is why systematic approaches to inkjet printer inks comparison and identification have been carried out by both non-destructive and destructive methods. In this study, micro-Raman spectroscopy and capillary electrophoresis (CE) were applied to the analysis of colour inkjet printer inks. Micro-Raman spectroscopy was used to study the chemical composition of colour inks in situ on a paper surface. It helps to characterize and differentiate inkjet inks, and can be used to create a spectra database of inks taken from different cartridge brands and cartridge numbers. Capillary electrophoresis in micellar electrophoretic capillary chromatography mode was applied to separate colour and colourless components of inks, enabling group identification of those components which occur in a sufficient concentration (giving intensive peaks). Finally, on the basis of the obtained results, differentiation of the analysed inks was performed. Twenty-three samples of inkjet printer inks were examined and the discriminating power (DP) values for both presented methods were established in the routine work of experts during the result interpretation step. DP was found to be 94.0% (Raman) and 95.6% (CE) when all the analysed ink samples were taken into account, and it was 96.7% (Raman) and 98.4% (CE), when only cartridges with different index numbers were considered.

  15. 21 CFR 864.7440 - Electrophoretic hemoglobin analysis system. (United States)


    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Electrophoretic hemoglobin analysis system. 864....7440 Electrophoretic hemoglobin analysis system. (a) Identification. An electrophoretic hemoglobin... hemoglobin types as an aid in the diagnosis of anemia or erythrocytosis (increased total red cell mass)...

  16. Capillary zone electrophoresis for analysis of phytochelatins and other thiol peptides in complex biological samples derivatized with monobromobimane. (United States)

    Perez-Rama, Mónica; Torres Vaamonde, Enrique; Abalde Alonso, Julio


    A new method to improve the analysis of phytochelatins and their precursors (cysteine, gamma-Glu-Cys, and glutathione) derivatized with monobromobimane (mBrB) in complex biological samples by capillary zone electrophoresis is described. The effects of the background electrolyte pH, concentration, and different organic additives (acetonitrile, methanol, and trifluoroethanol) on the separation were studied to achieve optimum resolution and number of theoretical plates of the analyzed compounds in the electropherograms. Optimum separation of the thiol peptides was obtained with 150 mM phosphate buffer at pH 1.60. Separation efficiency was improved when 2.5% v/v methanol was added to the background electrolyte. The electrophoretic conditions were 13 kV and capillary dimensions with 30 cm length from the inlet to the detector (38 cm total length) and 50 microm inner diameter. The injection was by pressure at 50 mbar for 17 s. Under these conditions, the separation between desglycyl-peptides and phytochelatins was also achieved. We also describe the optimum conditions for the derivatization of biological samples with mBrB to increase electrophoretic sensitivity and number of theoretical plates. The improved method was shown to be simple, reproducible, selective, and accurate in measuring thiol peptides in complex biological samples, the detection limit being 2.5 microM glutathione at a wavelength of 390 nm.

  17. A chip-type thin-layer electrochemical cell coupled with capillary electrophoresis for online separation of electrode reaction products

    Energy Technology Data Exchange (ETDEWEB)

    He, Jian-Bo, E-mail:; Cui, Ting; Zhang, Wen-Wen; Deng, Ning


    Graphical abstract: -- Highlights: •A new coupling of thin-layer electrolysis with capillary electrophoresis (CE). •Rapid electrolysis, direct sampling followed by online CE separation. •At least 13 products of quercetin oxidation were separated. •Thermodynamic and kinetic parameters were determined from CE peak areas. -- Abstract: A coupling technique of thin-layer electrolysis with high-performance capillary electrophoresis/UV–vis technique(EC/HPCE/UV–vis) is developed for online separation and determination of electrode reaction products. A chip-type thin-layer electrolytic (CTE) cell was designed and fabricated, which contains a capillary channel and a background electrolyte reservoir, allowing rapid electrolysis, direct sampling and online electrophoretic separation. This chip-type setup was characterized based on an electrophoresis expression of Nernst equation that was applied to the redox equilibrium of o-tolidine at different potentials. The utility of the method was demonstrated by separating and determining the electro-oxidation products of quercetin in different pH media. Two main products were always found in the studied time, potential and pH ranges. The variety of products increased not only with increasing potential but also with increasing pH value, and in total, at least 13 products were observed in the electropherograms. This work illustrates a novel example of capillary electrophoresis used online with thin-layer electrolysis to separate and detect electrode reaction products.

  18. Nitromethane as solvent in capillary electrophoresis. (United States)

    Subirats, Xavier; Porras, Simo P; Rosés, Martí; Kenndler, Ernst


    Nitromethane has several properties that make it an interesting solvent for capillary electrophoresis especially for lipophilic analytes that are not sufficiently soluble in water: freezing and boiling points are suitable for laboratory conditions, low viscosity leads to favourable electrophoretic mobilities, or an intermediate dielectric constant enables dissolution of electrolytes. In the present work we investigate the change of electrophoretically relevant analyte properties - mobilities and pKa values - in nitromethane in dependence on the most important experimental conditions determined by the background electrolyte: the ionic strength, I, and the pH. It was found that the mobility decreases with increasing ionic strength (by, e.g. up to 30% from I = 0 to 50 mmol/L) according to theory. An appropriate pH scale is established by the aid of applying different concentration ratios of a buffer acid with known pKa and its conjugate base. The mobility of the anionic analytes (from weak neutral acids) depends on the pH with the typical sigmoidal curve in accordance with theory. The pKa of neutral acids derived from these curves is shifted by as much as 14 pK units in nitromethane compared to water. Both findings confirm the agreement of the electrophoretic behaviour of the analytes with theories of electrolyte solutions. Separation of several neutral analytes was demonstrated upon formation of charged complexes due to heteroconjugation with chloride as ionic constituent of the background electrolyte.

  19. Chiral anion exchangers applied to capillary electrochromatography enantioseparation of oppositely charged chiral analytes: investigation of stationary and mobile phase parameters. (United States)

    Lämmerhofer, M; Tobler, E; Lindner, W


    Weak anion-exchange (WAX) type chiral stationary phases (CSPs) based on tert.-butyl carbamoyl quinine as chiral selector (SO) and different types of silica particles (porous and non-porous) as chromatographic support are evaluated in packed capillary electrochromatography (CEC). Their ability to resolve the enantiomers of negatively charged chiral analytes, e.g., N-derivatized amino acids, in the anion-exchange mode and their electrochromatographic characteristics are described in dependence of several mobile phase parameters (pH, buffer type and concentration, organic modifier type and concentration) and other experimental variables (electric field strength, capillary temperature). The inherent "zwitterionic" surface character of such silica-based WAX type CSPs (positively charged SO and negatively charged residual silanols) allows the reversal of the electroosmotic flow (EOF) towards the anode at pH values below the isoelectric point (pI) of the modified surface, whereas a cathodic EOF results at pH values above the pI. Since for negatively charged analytes also an electrophoretic transport increment has to be considered, which can be either in or against the EOF direction, several distinct modes of elution have been observed under different stationary phase and mobile phase conditions: (i) co-electrophoretic elution of the negatively charged solutes with the anodic EOF in the negative polarity mode, (ii) counter-electrophoretic elution with the cathodic EOF in the positive polarity mode, and (iii) electrophoretically dominated elution in the negative polarity mode with a cathodic EOF directed to the injection end of the capillary. Useful enantioseparations of chiral acids have been obtained with all three modes. Enantioselectivity values as high as under pressure-driven conditions and theoretical plate numbers up to 120000 per meter could be achieved under electrically driven conditions. A repeatability study yielded RSD values below 2% for retention times and

  20. Estudio del perfil electroforético en sueros de caninos con leishmaniasis visceral de Posadas, provincia de Misiones, Argentina Study of the sera electrophoretic profile in dogs infected with visceral leishmaniasis from Posadas, Misiones, Argentina

    Directory of Open Access Journals (Sweden)

    L.G. Ramayo


    Full Text Available La leishmaniasis visceral es una enfermedad zoonótica producida por el protozoario Leishmania infantum (syn. chagasi transmitida por el flebótomo Lutzomyia longipalpis y que tiene al canino como principal reservorio en áreas urbanas y periurbanas. En el presente trabajo se realizó un estudio electroforético retrospectivo de 40 sueros de caninos enfermos con diagnóstico parasitológico confirmado de leishmaniasis obtenidos entre los años 2006 y 2008 en la ciudad de Posadas, provincia de Misiones, Argentina. El 80 % (32 de 40 de las muestras presentaron alteraciones en el perfil electroforético caracterizadas por la disminución de la relación albúmina/globulina y la presencia de hipergammaglobulinemia de tipo policlonal en el 52,5 % de los casos (21 de 40 y de hipergammaglobulinemia de tipo monoclonal a isotipo IgG en el 27,5 % (11 de 40 de ellos. Cinco de los sueros con anormalidades en el perfil electroforético mostraron valores normales de proteinemia; el resto presentó hiperproteinemia. Estos resultados muestran que la hipergammaglobulinemia y la disminución de la relación albúmina/globulina fueron hallazgos clínico patológicos frecuentes en este brote, tal como se describe en otras partes del mundo.Visceral leishmaniasis in a zoonotic disease caused by protozoan Leishmania infantum (syn. chagasi, transmited by phlebotomine Lutzomyia longipalpis. Canines are its main reservoir in urban and suburban areas. Forty sera from sick dogs with leishmaniasis confirmed by parasitological diagnosis were analized in a retrospective study. Sera were obtained during 2006-2008 in the city of Posadas, Misiones province, Argentina. Eighty % (32 out of 40 of these samples showed distortions in the electrophoretic profile, characterized by a diminished albumin/globulin ratio and the presence of polyclonal hypergammaglobulinemia in 52.5 % (21 out of 40 of the samples, or IgG-monoclonal hypergammaglobulinemia in 27.5 % (11 out of 40 of the

  1. Experimental Study of Capillary Effect in Porous Silicon Using Micro-Raman Spectroscopy and X-Ray Diffraction

    Institute of Scientific and Technical Information of China (English)

    LEI Zhen-Kun; KANG Yi-Lan; QIU Yu; HU Ming; CEN Hao


    We investigate the capillary effect and the residual stress evolution in the wetting, drying and rewetting stages of porous silicon using x-ray diffraction and micro-Raman spectroscopy. A reversible capillary effect and an irreversible oxidation effect are the driving forces for the residual stress evolution. The lattice expansion of the porous-silicon layer is observed to decrease slightly by x-ray diffraction and the tensile residual stress increases rapidly by micro-Raman spectroscopy, with the change of about 82 MPa for the oxidation effect and the change of 2.78 GPa (enough for cracking) for the capillary effect. Therefore, the capillary effect plays a major role in the residual stress evolution in the stages. A simple microscopic liquid-bridge model is introduced to explain the capillary effect and its reversibility. The capillary emergence has a close relation with a great deal of the micro-pore structure of porous silicon.

  2. Capillary zone electrophoresis analysis and detection of mid-spectrum biological warfare agents

    Energy Technology Data Exchange (ETDEWEB)

    Boulet, C.A.; Townsley, C.


    DRE Suffield has initiated a research program to develop methods and equipment for field detection and laboratory identification of mid-spectrum agents, molecules of biological origin such as proteins, peptides and toxins. In this study, a highly efficient and reproducible capillary zone electrophoresis method was developed to separate and identify a series of nine peptides of defence interest: bradykinin, bradykinin fragment 1-5, substance P,ARG8-vasopressin, luteinizing hormone releasing hormone, bombesin, leucine enkephalin, methionine enkephalin, and oxytocin. Using a 50 micrometer x 47 cm capillary column, 22.5 kV separation voltage and a 100 mM pH 2.5 phosphate buffer, all nine peptide could separated in under 10 minutes. Three strategies, which could be used in a fully automated field detection and identification system, were demonstrated for the identification of unknown peptides: comparison of migration times, comparison of electrophoretic mobilities, and co-injection of multiple reference standards. These experiments demonstrate that a separation based analytical method such as capillary electrophoresis could form the basis of a generic detection system for mid-spectrum protein and peptide toxins.

  3. Chiral separation of benzoporphyrin derivative mono- and diacids by laser induced fluorescence-capillary electrophoresis. (United States)

    Peng, Xuejun; Sternberg, Ethan; Dolphin, David


    A method for the separation of benzoporphyrin derivative mono- and diacid (BPDMA, BPDDA) enantiomers by laser induced fluorescence-capillary electrophoresis (LIF-CE) has been developed. By using 300 mM borate buffer, pH 9.2, 25 mM sodium cholate and 10% acetronitrile as electrolyte, +10 kV electrokinetic sampling injection of 2 s and an applied +20 kV voltage across the ends of a 37 cm capillary (30 cm to the detector, 50 microm ID), all six BPD stereoisomers were baseline-separated within 20 min. Formation constants, free electrophoretic and complexation mobilities with borate and cholate were determined based on dynamic complexation capillary electrophoresis theory. The BPD enantiomers can be quantitatively determined in the range of 10(-2)-10(-5) mg mL(-1). The correlation coefficients (r2) of the least-squares linear regression analysis of the BPD enantiomers are in the range of 0.9914-0.9997. Their limits of detection are 2.18-3.5 x 10(-3) mg mL(-1). The relative standard deviations for the separation were 2.90-4.64% (n = 10). In comparison with high-performance liquid chromatography (HPLC), CE has better resolution and efficiency. This separation method was successfully applied to the BPD enantiomers obtained from a matrix of bovine serum and from liposomally formulated material as well as from studies with rat, dog and human microsomes.

  4. Leukocytes in capillary flow. (United States)

    Schmid-Schönbein, G W; Lee, J


    During disease, the flow of blood cells through the capillary network is one of the most perilous events in the microcirculation. Capillary distensibility, cytoplasmic activity of endothelial cells, red cells and leukocytes play an important role in capillary perfusion. Occlusion of capillaries is one of the early signs of vascular failure and is encountered in many different conditions and organs. Adhesion of leukocytes to the endothelium via expression of membrane adhesion molecules leads to microvascular entrapment with capillary occlusion.

  5. Electrochemical Enzyme Immunoassay of Tumor Marker CA15-3 with Capillary Electrophoresis

    Institute of Scientific and Technical Information of China (English)


    Tumor marker CA15-3 was determined by using capillary electrophoretic enzyme immunoassay with electrochemical detection (CE-EIA-ED). The method can be used to detect CA15-3 with a limit of 0.024 U/mL.

  6. Diamond electrophoretic microchips-Joule heating effects

    Energy Technology Data Exchange (ETDEWEB)

    Karczemska, Anna T., E-mail: [Technical University of Lodz, Institute of Turbomachinery, 219/223 Wolczanska str., Lodz (Poland); Witkowski, Dariusz [Technical University of Lodz, Institute of Turbomachinery, 219/223 Wolczanska str., Lodz (Poland); Ralchenko, Victor, E-mail: [General Physics Institute, Russian Academy of Science, 38 Vavilov str., Moscow (Russian Federation); Bolshakov, Andrey; Sovyk, Dmitry [General Physics Institute, Russian Academy of Science, 38 Vavilov str., Moscow (Russian Federation); Lysko, Jan M., E-mail: [Institute of Electron Technology, Al. Lotnikow 32/46, 02-668 Warsaw (Poland); Fijalkowski, Mateusz, E-mail: [Technical University of Liberec, Faculty of Mechanical Engineering (Czech Republic); Bodzenta, Jerzy, E-mail: [Silesian University of Technology, Institute of Physics, 2 Krzywoustego str., 44-100 Gliwice (Poland); Hassard, John, E-mail: [Imperial College of Science, Technology and Medicine, London (United Kingdom)


    Microchip electrophoresis (MCE) has become a mature separation technique in the recent years. In the presented research, a polycrystalline diamond electrophoretic microchip was manufactured with a microwave plasma chemical vapour deposition (MPCVD) method. A replica technique (mould method) was used to manufacture microstructures in diamond. A numerical analysis with CoventorWare{sup TM} was used to compare thermal properties during chip electrophoresis of diamond and glass microchips of the same geometries. Temperature distributions in microchips were demonstrated. Thermal, electrical, optical, chemical and mechanical parameters of the polycrystalline diamond layers are advantageous over traditionally used materials for microfluidic devices. Especially, a very high thermal conductivity coefficient gives a possibility of very efficient dissipation of Joule heat from the diamond electrophoretic microchip. This enables manufacturing of a new generation of microdevices.

  7. Contact Angle Effects on Pore and Corner Arc Menisci in Polygonal Capillary Tubes Studied with the Pseudopotential Multiphase Lattice Boltzmann Model

    Directory of Open Access Journals (Sweden)

    Soyoun Son


    Full Text Available In porous media, pore geometry and wettability are determinant factors for capillary flow in drainage or imbibition. Pores are often considered as cylindrical tubes in analytical or computational studies. Such simplification prevents the capture of phenomena occurring in pore corners. Considering the corners of pores is crucial to realistically study capillary flow and to accurately estimate liquid distribution, degree of saturation and dynamic liquid behavior in pores and in porous media. In this study, capillary flow in polygonal tubes is studied with the Shan-Chen pseudopotential multiphase lattice Boltzmann model (LBM. The LB model is first validated through a contact angle test and a capillary intrusion test. Then capillary rise in square and triangular tubes is simulated and the pore meniscus height is investigated as a function of contact angle θ. Also, the occurrence of fluid in the tube corners, referred to as corner arc menisci, is studied in terms of curvature versus degree of saturation. In polygonal capillary tubes, the number of sides leads to a critical contact angle θc which is known as a key parameter for the existence of the two configurations. LBM succeeds in simulating the formation of a pore meniscus at θ > θc or the occurrence of corner arc menisci at θ < θc. The curvature of corner arc menisci is known to decrease with increasing saturation and decreasing contact angle as described by the Mayer and Stoewe-Princen (MS-P theory. We obtain simulation results that are in good qualitative and quantitative agreement with the analytical solutions in terms of height of pore meniscus versus contact angle and curvature of corner arc menisci versus saturation degree. LBM is a suitable and promising tool for a better understanding of the complicated phenomena of multiphase flow in porous media.

  8. A unified mathematical theory of electrophoretic processes (United States)

    Bier, M.; Palusinski, O. A.; Mosher, R. A.; Graham, A.; Saville, D. A.


    A mathematical theory is presented which shows that each of the four classical electrophoretic modes (zone electrophoresis, moving boundary electrophoresis, isotachophoresis, and isoelectric focusing) is based on the same general principles and can collectively be described in terms of a single set of equations. This model can predict the evolution of the four electrophoretic modes as a function of time. The model system is one-dimensional, neglecting the effects of electroosmosis, temperature gradients, and any bulk flows of liquid. The model is based on equations which express the components' dissociation equilibria, the mass transport due to electromigration and diffusion, electroneutrality, and the conservation of mass and charge. The model consists of a system of coupled partial differential and nonlinear algebraic equations which can be solved numerically by use of a computer. The versatility of this model was verified using an example of a three-component system containing cacodylate, tris hydroxylmethylaminomethane, and histidine. Results show that this model not only correctly predicts the characteristic features of each electrophoretic mode, but also gives details of the concentration, pH, and conductivity profiles not easily amenable to direct experimental measurement.

  9. Aggregation behavior of fullerenes in aqueous solutions: a capillary electrophoresis and asymmetric flow field-flow fractionation study

    NARCIS (Netherlands)

    A. Astefanei; O. Núñez; M.T. Galceran; W.Th. Kok; P.J. Schoenmakers


    In this work, the electrophoretic behavior of hydrophobic fullerenes [buckminsterfullerene (C-60), C-70, and N-methyl-fulleropyrrolidine (C-60-pyrr)] and water-soluble fullerenes [fullerol (C-60(OH)(24)); polyhydroxy small gap fullerene, hydrated (C-120(OH)(30)); C-60 pyrrolidine tris acid (C-60-pyr

  10. Study of a capillary evaporator; Etude d`un evaporateur capillaire

    Energy Technology Data Exchange (ETDEWEB)

    Figus, C.; Le Bray, Y.; Bories, S.; Prat, M. [Institut de Mecanique des Fluides, 31 - Toulouse (France)


    The phenomena that occur during heat and mass transfers by vaporization in porous medium can be described in various ways depending on the length-scale chosen. The most rigorous method is the one that uses the classical fluid mechanics equations to describe the phenomena at each point and in each phase of the domain considered. However, because of the geometrical complexity of the porous domain, this microscopic description is generally unusable. In order to get round this difficulty, the notion of fictive continuum is used to describe the phenomena at a macroscopic scale. In a first step, a numerical model is proposed which is based on the heat and mass transfer equations applied to a representative elementary volume. This approach allows to describe the development of a vapor pocket beneath the flange and to determine the dimensioning sizes of the capillary evaporator. In a second step, a model with a simplified geometry, called numerical network, which represents each pore of a given evaporator structure and which describes the heat and mass transfers at this scale is developed. This second approach confirms the previous results and allows to reach the mechanisms linked with the microstructure heterogeneities (percolation accidents, influence of microscopic heterogeneities..). (J.S.)

  11. due to Capillary Forces

    Directory of Open Access Journals (Sweden)

    Hassen M. Ouakad


    Full Text Available We present modeling and analysis for the static behavior and collapse instabilities of doubly-clamped and cantilever microbeams subjected to capillary forces. These forces can be as a result of a volume of liquid trapped underneath the microbeam during the rinsing and drying process in fabrication. The model considers the microbeam as a continuous medium, the capillary force as a nonlinear function of displacement, and accounts for the mid-plane stretching and geometric nonlinearities. The capillary force is assumed to be distributed over a specific length underneath the microbeam. The Galerkin procedure is used to derive a reduced-order model consisting of a set of nonlinear algebraic and differential equations that describe the microbeams static and dynamic behaviors. We study the collapse instability, which brings the microbeam from its unstuck configuration to touch the substrate and gets stuck in the so-called pinned configuration. We calculate the pull-in length that distinguishes the free from the pinned configurations as a function of the beam thickness and gap width for both microbeams. Comparisons are made with analytical results reported in the literature based on the Ritz method for linear and nonlinear beam models. The instability problem, which brings the microbeam from a pinned to adhered configuration is also investigated. For this case, we use a shooting technique to solve the boundary-value problem governing the deflection of the microbeams. The critical microbeam length for this second instability is also calculated.

  12. Capillary electrophoresis with laser-induced fluorescence detection for studying amino acid uptake by yeast during beer fermentation. (United States)

    Turkia, Heidi; Sirén, Heli; Penttilä, Merja; Pitkänen, Juha-Pekka


    The amino acid composition of cultivation broth is known to affect the biomass accumulation, productivity, and vitality of yeast during cultivation. A separation method based on capillary electrophoresis with laser-induced fluorescence (LIF) detection was developed for the determination of amino acid consumption by Saccharomyces cerevisiae during beer fermentation. Intraday relative standard deviations were less than 2.1% for migration times and between 2.9% and 9.9% for peak areas. Interday relative standard deviations were less than 2.5% for migration times and between 4.4% and 18.9% for peak areas. The quantification limit was even as low as 62.5 pM which equals to below attomole level detection. The method was applied to study the rate of amino acid utilization during beer fermentation.

  13. Toxinological and immunological studies of capillary electrophoresis fractionated Chrysaora quinquecirrha (Desor) fishing tentacle and Chironex fleckeri Southcott nematocyst venoms. (United States)

    Bloom, D A; Radwan, F F; Burnett, J W


    Repeated runs of capillary electrophoresis (CE) were used to study partially-purified jellyfish nematocyst venom protein in concentrations sufficient to perform toxinological assays. Nematocyst venoms from Chironex fleckeri (Cf) and Chysaora quinquecirrha were processed. The CE eluate was divided into quadrants by scanning protein content. The fourth fraction of both jellyfish venoms, contained proteins with the smallest molecular weight components, which were responsible for the highest hemolysins and the humoral and cell-mediated immunological activity. Cytotoxic Cf lethal factor activity against human liver cells was widely dispersed throughout both venoms but more prominent in fraction 4. A V(beta) receptor human T-cell repertoire was not species-specific for either crude or fractionated jellyfish nematocyst venom.

  14. Study of Interaction between Red-tide Toxin, Domoic Acid and Double -stranded DNA by Capillary Zone Electrophoresis

    Institute of Scientific and Technical Information of China (English)

    Da Zhi LI; Xin Ya HE; Hui WANG; Li SUN; Bing Cheng LIN


    The interactions between amnesic red-tide toxin, domoic acid (DA) and 14mer double-stranded DNA (dsDNA with three kinds of sequences) were studied by capillary zone electrophoresis (CZE). For the dsDNA with a sequence of 5'-CCCCCTATACCCGC-3', the amount of free dsDNA decreases with the increase of added DA; and the signal of DA-dsDNA complex was observed. Meanwhile, the other two dsDNAs, 5'-(C)12GC-3' and 5'-(AT)7-3', the existence of DA could not lead to the change of dsDNA signal and indicated that there is no interaction between DA and these two dsDNAs.

  15. Direct Imaging of Single Plasmonic Metal Nanoparticles in Capillary with Laser Light-Sheet Scattering Imaging. (United States)

    Cao, Xuan; Feng, Jingjing; Pan, Qi; Xiong, Bin; He, Yan; Yeung, Edward S


    Understanding the heterogeneous distribution of the physical and chemical properties of plasmonic metal nanoparticles is fundamentally important to their basic and applied research. Traditionally, they are obtained either indirectly via bulk spectroscopic measurements plus electron microscopic characterizations or through single molecule/particle imaging of nanoparticles immobilized on planar substrates. In this study, by using light-sheet scattering microscopy with a supercontinuum white laser, highly sensitive imaging of individual metal nanoparticles (MNPs) flowing inside a capillary, driven by either pressure or electric field, was achieved for the first time. We demonstrate that single plasmonic nanoparticles with different size or chemical modification could be differentiated through their electrophoretic mobility in a few minutes. This technique could potentially be applied to high throughput characterization and evaluation of single metal nanoparticles as well as their dynamic interactions with various local environments.

  16. Capillary and sorbed water content in wood as studied by nuclear magnetic resonance; Badanie zawartosci wody wolnej i zwiazanej w drewnie metoda magnetycznego rezonansu jadrowego

    Energy Technology Data Exchange (ETDEWEB)

    Olek, W.; Baranowska, H.M.; Guzenda, R.; Olszewski, K.J. [Akademia Rolnicza, Poznan (Poland)


    Water content in wood has been studied by NMR technique. The spin-spin relaxation time has been measured for distinguish the capillary and sorbed water. The qualitative and quantitative determination have been possible by means of proposed method. 8 refs, 6 figs.

  17. Electrophoretic separation techniques and their hyphenation to mass spectrometry in biological inorganic chemistry. (United States)

    Holtkamp, Hannah; Grabmann, Gerlinde; Hartinger, Christian G


    Electrophoretic methods have been widely applied in research on the roles of metal complexes in biological systems. In particular, CE, often hyphenated to a sensitive MS detector, has provided valuable information on the modes of action of metal-based pharmaceuticals, and more recently new methods have been added to the electrophoretic toolbox. The range of applications continues to expand as a result of enhanced CE-to-MS interfacing, with sensitivity often at picomolar level, and evolved separation modes allowing for innovative sample analysis. This article is a followup to previous reviews about CE methods in metallodrug research (Electrophoresis, 2003, 24, 2023-2037; Electrophoresis, 2007, 28, 3436-3446; Electrophoresis, 2012, 33, 622-634), also providing a comprehensive overview of metal species studied by electrophoretic methods hyphenated to MS. It highlights the latest CE developments, takes a sneak peek into gel electrophoresis, traces biomolecule labeling, and focuses on the importance of early-stage drug development.

  18. Cathodic electrophoretic deposition ofα-Fe2O3 coating

    Institute of Scientific and Technical Information of China (English)

    马莉; 常通; 李小斌; 李志友; 张斗; 周科朝


    Submicroα-Fe2O3 coatings were formed using electrophoretic deposition (EPD) technique in aqueous media. The zeta potentials of differentα-Fe2O3 suspensions with different additives were measured as a function of pH to identify the optimum suspension condition for deposition. Electrophoretic depositions ofα-Fe2O3 coatings under different applied electric fields and deposition time were studied and the effects of applied voltages and deposition time on deposition rates and thicknesses were investigated. The particle packing densities of the deposits at various applied voltages and deposition time were also analyzed by a scanning electron microscope (SEM). The results show that crack-freeα-Fe2O3 coatings with uniform microstructure and good adherence to the nickel substrates are successfully obtained. Electrophoretic depositedα-Fe2O3 coating from aqueous suspension is a feasible, low-cost and environmental friendly method.

  19. Electrophoretic mobilities of dissolved polyelectrolyte charging agent and suspended non-colloidal titanium during electrophoretic deposition

    Energy Technology Data Exchange (ETDEWEB)

    Lau, Kok-Tee [School of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Faculty of Manufacturing Engineering, Universiti Teknikal Malaysia Melaka, 76109 Durian Tunggal, Melaka (Malaysia); Sorrell, C.C., E-mail: [School of Materials Science and Engineering, University of New South Wales, Sydney, NSW 2052 (Australia)


    Coarse ({<=}20 {mu}m) titanium particles were deposited on low-carbon steel substrates by cathodic electrophoretic deposition (EPD) with ethanol as suspension medium and poly(diallyldimethylammonium chloride) (PDADMAC) as polymeric charging agent. Preliminary data on the electrophoretic mobilities and electrical conductivities on the suspensions of these soft particles as well as the solutions themselves as a function of PDADMAC level were used as the basis for the investigation of the EPD parameters in terms of the deposition yield as a function of five experimental parameters: (a) PDADMAC addition level, (b) solids loading, (c) deposition time, (d) applied voltage, and (e) electrode separation. These data were supported by particle sizing by laser diffraction and deposit surface morphology by scanning electron microscopy (SEM). The preceding data demonstrated that Ti particles of {approx}1-12 {mu}m size, electrosterically modified by the PDADMAC charging agent, acted effectively as colloidal particles during EPD. Owing to the non-colloidal nature of the particles and the stabilization of the Ti particles by electrosteric forces, the relevance of the zeta potential is questionable, so the more fundamental parameter of electrophoretic mobility was used. A key finding from the present work is the importance of assessing the electrophoretic mobilities of both the suspensions and solutions since the latter, which normally is overlooked, plays a critical role in the ability to interpret the results meaningfully. Further, algebraic uncoupling of these data plus determination of the deposit yield as a function of charging agent addition allow discrimination between the three main mechanistic stages of the electrokinetics of the process, which are: (1) surface saturation; (2) compression of the diffuse layer, growth of polymer-rich layer, and/or competition between the mobility of Ti and PDADMAC; and (3) little or no decrease in electrophoretic mobility of Ti

  20. Nonaqueous capillary electrophoresis of imatinib mesylate and related substances. (United States)

    Ye, Lei; Huang, Yifei; Li, Jian; Xiang, Guangya; Xu, Li


    In the present study, nonaqueous capillary electrophoretic separation of imatinib mesylate (IM) and related substances, N-(5-amino-2-methylphenyl)-4-(3-pyridyl)-2-pyrimidinamine (PYA), N-(4-methyl-3-(4-(pyridin-3-yl)pyrimidin-2-ylamino)phenyl)-4-((piperazin-1-yl)methyl) benzamide (NDI) and 4-chloromethyl-N-(4-methyl-3-((4-(pyridin-3-yl) pyrimidin-2-yl) amino) phenyl) benzamide (CPB) was developed. The influential factors affecting separation, including type and concentration of the electrolyte, applied voltage, and buffer modifier were investigated. Baseline separation of the studied analytes was obtained using a buffer of 50 mM Tris and 50 mM methanesulfonic acid in methanol at a apparent pH (pH*) of 1.65. To enhance the sensitivity, large-volume sample stacking was employed for online concentration. The strongest analytical signal with a suitable separation was achieved when the injection time was 100 s. The linearity ranges of PYA and NDI were 0.100-2.50 μg mL(-1), and that of CPB was 0.125-2.50 μg mL(-1), with good coefficients (r(2) > 0.9948). The relative standard deviations of intra- and interday were satisfactory. Under the optimized conditions, seven batches of the synthesized samples were analyzed and CPB was detected in two batches. Owing to its simplicity, effectiveness, and low price, the developed method is promising for quality control of IM.

  1. Contactless conductometric determination of methanol and ethanol in samples containing water after their electrophoretic desalination. (United States)

    Tůma, Petr; Opekar, František


    Determination of the contents of methanol and ethanol in aqueous solutions was performed by measuring the permittivity of solutions using a contactless conductivity detector (C(4) D) normally used for detection in capillary electrophoresis. The detection cell is a section of a fused silica capillary with an internal diameter of 50 μm with a pair of conductivity electrodes on the external walls. The C(4) D response to samples of methanol/water and ethanol/water mixtures is linear in the concentration interval of approx. 40-100% v/v alcohol content. In the analysis of technical samples of methanol and ethanol, the determination is disturbed by the presence of even trace amounts of salts. This interference can be effectively eliminated by integrated electrophoretic desalination of the sample by the application of a direct current electric voltage with a magnitude of 10 kV to the capillary with the injected sample zone. Under these conditions, the ions migrate out of the sample zone and the detector response is controlled purely by the permittivity of the solvent/water zone. Desalinating is effective for NaCl contents in the range from 0 to 5 mmol/L NaCl. The effectiveness of the desalinating process has been verified on MeOH/water samples and in determination of the ethanol content in distilled beverages normally available in the retail network.

  2. Applications of graphene electrophoretic deposition. A review. (United States)

    Chavez-Valdez, A; Shaffer, M S P; Boccaccini, A R


    This Review summarizes research progress employing electrophoretic deposition (EPD) to fabricate graphene and graphene-based nanostructures for a wide range of applications, including energy storage materials, field emission devices, supports for fuel cells, dye-sensitized solar cells, supercapacitors and sensors, among others. These carbonaceous nanomaterials can be dispersed in organic solvents, or more commonly in water, using a variety of techniques compatible with EPD. Most deposits are produced under constant voltage conditions with deposition time also playing an important role in determining the morphology of the resulting graphene structures. In addition to simple planar substrates, it has been shown that uniform graphene-based layers can be deposited on three-dimensional, porous, and even flexible substrates. In general, electrophoretically deposited graphene layers show excellent properties, e.g., high electrical conductivity, large surface area, good thermal stability, high optical transparency, and robust mechanical strength. EPD also enables the fabrication of functional composite materials, e.g., graphene combined with metallic nanoparticles, with other carbonaceous materials (e.g., carbon nanotubes) or polymers, leading to novel nanomaterials with enhanced optical and electrical properties. In summary, the analysis of the available literature reveals that EPD is a simple and convenient processing method for graphene and graphene-based materials, which is easy to apply and versatile. EPD has, therefore, a promising future for applications in the field of advanced nanomaterials, which depend on the reliable manipulation of graphene and graphene-containing systems.

  3. Cyclic electrophoretic and chromatographic separation methods

    NARCIS (Netherlands)

    Eijkel, Jan C.T.; Berg, van den Albert; Manz, Andreas


    A review is given of the application of cyclic analytical methods in capillary electroseparation (CE) and liquid chromatography (LC) systems. Cyclic methods have been used since the early sixties in chromatographic systems to overcome pressure limitations to resolution. From the early nineties on th

  4. In-situ studies on the performance of landfill caps (compacted soil liners, geomembranes, geosynthetic clay liners, capillary barriers)

    Energy Technology Data Exchange (ETDEWEB)

    Melchior, S. [IGB - Ingenieurbuero fuer Grundbau, Hamburg (Germany)


    Since 1986 different types of landfill covers have been studied in-situ on the Georgswerder landfill in Hamburg, Germany. Water balance data are available for eight years. The performance of different carriers has been measured by collecting the leakage on areas ranging from 100 m{sup 2} to 500 m{sup 2}. Composite liners with geomembranes performed best, showing no leakage. An extended capillary barrier also performed well. The performance of compacted soil liners, however, decreased severely within five years due to desiccation, shrinkage and plant root penetration (liner leakage now ranging from 150 mm/a to 200 mm/a). About 50 % of the water that reaches the surface of the liner is leaking through it. The maximum leakage rates have increased from 2 x 10{sup -10} m{sup 3} m{sup -2} s{sup -1} to 4 x 10{sup -8} m{sup 3} m{sup -2} s{sup -1}. Two types of geosynthetic clay liners (GCL) have been tested for two years now with disappointing results. The GCL desiccated during the first dry summer of the study. High percolation rates through the GCL were measured during the following winter (45 mm resp. 63 mm in four months). Wetting of the GCL did not significantly reduce the percolation rates.

  5. Study of the interactions between fluoroquinolones and human serum albumin by affinity capillary electrophoresis and fluorescence method

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Liwei; Wang Kun [Beijing National Laboratory for Molecular Sciences (BNLMS), College of Chemistry, Peking University, Beijing 100871 (China); Zhang Xinxiang [Beijing National Laboratory for Molecular Sciences (BNLMS), College of Chemistry, Peking University, Beijing 100871 (China)], E-mail:


    The interactions between fluoroquinolones and human serum albumin (HSA) were investigated by affinity capillary electrophoresis (ACE) and fluorescence quenching technique. Based on the efficient separation of several fluoroquinolones using a simple phosphate buffer, the binding constants of fluoroquinolones with HSA were determined simultaneously during one set of electrophoresis by ACE method. The thermodynamic parameters were obtained from data at different temperatures, and the negative {delta}H and {delta}S values showed that both hydrogen bonds and van der Waals interaction played major roles in the binding of fluoroquinolones to HSA. The interactions were also studied by fluorescence quenching technique. The results of fluorescence titration revealed that fluoroquinolones had the strong ability to quenching the intrinsic fluorescence of HSA through the static quenching procedure. The binding site number n, apparent binding constant K{sub b} and the Stern-Volmer quenching constant K{sub sv} were determined. The thermodynamic parameters were also studied by fluorescence method, and the results were consonant with that of ACE.

  6. Studies on the structural variations of pentosan polysulfate sodium (NaPPS) from different sources by capillary electrophoresis. (United States)

    Degenhardt, M; Ghosh, P; Wätzig, H


    Commercial pentosan polysulfate sodium salts (NaPPS) are highly sulfated polysaccharides derived from beechwood hemicellulose by sulfate esterification with a Mrel range of 1500-6000. The polysaccharide backbone of NaPPS consists of repeating linear units of 1-4 linked beta-D-xylopyranose with laterally substituted 4-methylglucopyranosyluronic acid units glycosidically linked to the 2 position of the main chain at every 10th xylopyranose unit on average. For many years NaPPS has been used for antithrombotic prophylaxis in Europe and interstitial cystitis in the USA and Australia. More recently NaPPS has found veterinary application for the treatment of osteoarthritis and related conditions in domestic animals and is registered for this use in Australia, New Zealand, Canada, UK, Eire, and several Scandanavian countries. At present the use of NaPPS for human disorders is confined to material manufactured by one company. However, for veterinary applications, NaPPS from three manufactures have been described. Since it is well known that the biological activities of sulfated polysaccharides are dependent on their molecular structures we considered it important to characterise these various NaPPS preparations using an established method of analysis. Unfortunately, traditional analytical techniques such as TLC, OR, UV/Vis spectroscopy, and size exclusion chromatography were incapable of providing structural information which would distinguish these NaPPS preparations from each other. In contrast, a capillary zone electrophoresis (CZE) method facilitated characterisation of the different NaPPS by a highly reproducible fingerprint, using a benzene-1,2,4-tricarboxylic acid buffer (8.75 mmol/L, pH = 4.9) with indirect UV detection (lambda = 217 nm) and a special capillary pre-treatment (1 M NaOH for 1 h at 25 degrees C, then running buffer for 120 min at 25 degrees C applying -20 kV). In the present study more than 20 batches of NaPPS from the three manufacturers have been

  7. Separation of ions in acidic solution by capillary electrophoresis

    Energy Technology Data Exchange (ETDEWEB)

    Thornton, M.


    Capillary electrophoresis (CE) is an effective method for separating ionic species according to differences in their electrophoretic mobilities. CE separations of amino acids by direct detection are difficult due to their similar electrophoretic mobilities and low absorbances. However, native amino acids can be separated by CE as cations at a low pH by adding an alkanesulfonic acid to the electrolyte carrier which imparts selectivity to the system. Derivatization is unnecessary when direct UV detection is used at 185 nm. Simultaneous speciation of metal cations such as vanadium (IV) and vanadium (V) can easily be performed without complexation prior to analysis. An indirect UV detection scheme for acidic conditions was also developed using guanidine as the background carrier electrolyte (BCE) for the indirect detection of metal cations. Three chapters have been removed for separate processing. This report contains introductory material, references, and general conclusions. 80 refs.

  8. Fast capillary electrophoresis-time-of-flight mass spectrometry using capillaries with inner diameters ranging from 75 to 5 μm. (United States)

    Grundmann, Marco; Matysik, Frank-Michael


    Fast electrophoretic separations in fused silica capillaries (CE) coupled to time-of-flight mass spectrometry (TOF-MS) are presented. CE separations of the model analytes (epinephrine, norepinephrine, dopamine, histidine, and isoproterenol) under conditions of high electric field strengths of up to 1.25 kV cm(-1) are completed in 20 s. Coupling of CE with TOF-MS is accomplished using a coaxial sheath liquid electrospray ionization interface. The influence of parameters inherent to the interface and their effects, including suction pressure and dilution, are discussed. In addition to standard capillaries of 75 and 50 μm inner diameter (ID), separations in capillaries with IDs of 25, 15, and 5 μm have been successfully applied to this setup. The analytical performance is compared over this range of capillary dimensions, and both advantages and disadvantages are discussed.

  9. Complexation studies with lanthanides and humic acid analyzed by ultrafiltration and capillary electrophoresis-inductively coupled plasma mass spectrometry. (United States)

    Kautenburger, Ralf; Beck, Horst Philipp


    For the long-term storage of radioactive waste, detailed information about geo-chemical behavior of radioactive and toxic metal ions under environmental conditions is necessary. Humic acid (HA) can play an important role in the immobilisation or mobilisation of metal ions due to complexation and colloid formation. Therefore, we investigate the complexation behavior of HA and its influence on the migration or retardation of selected lanthanides (europium and gadolinium as homologues of the actinides americium and curium). Two independent speciation techniques, ultrafiltration and capillary electrophoresis coupled with inductively coupled plasma mass spectrometry (CE-ICP-MS) have been compared for the study of Eu and Gd interaction with (purified Aldrich) HA. The degree of complexation of Eu and Gd in 25 mg l(-1) Aldrich HA solutions was determined with a broad range of metal loading (Eu and Gd total concentration between 10(-6) and 10(-4) mol l(-1)), ionic strength of 10 mM (NaClO4) and different pH-values. From the CE-ICP-MS electropherograms, additional information on the charge of the Eu species was obtained by the use of 1-bromopropane as neutral marker. To detect HA in the ICP-MS and separate between HA complexed and non complexed metal ions in the CE-ICP-MS, we have halogenated the HA with iodine as ICP-MS marker.

  10. Enantiomeric separation of tapentadol by capillary electrophoresis--study of chiral selectivity manipulation by various types of cyclodextrins. (United States)

    Znaleziona, Joanna; Fejős, Ida; Ševčík, Juraj; Douša, Michal; Béni, Szabolcs; Maier, Vítězslav


    The chiral recognition of the centrally acting analgesic agent tapentadol and its isomers with various cyclodextrins (CDs) was studied by capillary electrophoresis, focusing on the migration order of four stereoisomers. In the case of non-charged hydroxypropylated CDs (2-hydroxypropyl-β-CD, 2-hydroxypropyl-γ-CD) the beta derivative was able to discriminate the S,R- and R,S-isomers in acidic background electrolyte, whereas the gamma allowed the separation of S,S- and R,R-tapentadol, respectively. Dual CD system containing both hosts was used to separate all of four isomers. Negatively charged sulfated-α-CD at 1.0% (w/v) concentration in 100mM sodium borate buffer (pH 9.5) was capable of separating the isomers with favorable enantiomer migration order and the optimized method was able to determine 0.15% of chiral impurities of tapentadol in the presence of the last migrating clinically important R,R-isomer.

  11. Combination of capillary electrophoresis, molecular modeling and NMR to study the enantioselective complexation of sulpiride with double cyclodextrin systems. (United States)

    Melani, Fabrizio; Pasquini, Benedetta; Caprini, Claudia; Gotti, Roberto; Orlandini, Serena; Furlanetto, Sandra


    The enantioselective complexation of sulpiride by a number of cyclodextrins (CDs) was deeply investigated by different techniques with the aim of evaluating the role of the used chiral selectors involved in the enantioseparation of the eutomer levosulpiride (S-SUL) and its dextro-isomer by capillary electrophoresis (CE). A CE method was previously developed with the aim of determining the optical purity of S-SUL and was based on the use of a dual cyclodextrin system, made by sulfated-β-cyclodextrin (SβCD) and methyl-β-cyclodextrin (MβCD). In this paper, a molecular modeling study made it possible to explain the different affinity of sulpiride enantiomers for several CDs, which had been tested during the early phase of CE method development. The potential and the gain energy of the inclusion complexes between the enantiomers and neutral and charged CDs were calculated on the minimized conformations. The calculated docking energies indicated that the most stable complexes were effectively obtained with SβCD and MβCD. A correlation between CE migration time of the last migrating enantiomer S-SUL and the stability of analyte-neutral CDs complexes was postulated. Furthermore, two-dimensional rotating-frame Overhauser effect spectroscopy NMR (2-D ROESY) experiments were carried out, which clearly indicated the formation of complexes and suggested the inclusion of the benzene sulfonamide moiety of S-SUL inside the hydrophobic cavity of the CDs.

  12. Electrophoretic mobility shift assays for the analysis of DNA-protein interactions. (United States)

    Gaudreault, Manon; Gingras, Marie-Eve; Lessard, Maryse; Leclerc, Steeve; Guérin, Sylvain L


    Electromobility shift assay is a simple, efficient, and rapid method for the study of specific DNA-protein interactions. It relies on the reduction in the electrophoretic mobility conferred to a DNA fragment by an interacting protein. The technique is suitable to qualitative, quantitative, and kinetic analyses. It can also be used to analyze conformational changes.

  13. Electrochemically powered self-propelled electrophoretic nanosubmarines (United States)

    Pumera, Martin


    In the past few years, we have witnessed rapid developments in the realization of the old nanotechnology dream, autonomous nanosubmarines. These nanomachines are self-powered, taking energy from their environment by electrocatalytic conversion of chemicals present in the solution, self-propelled by flux of the electrons within the submarine and the hydronium ions on the surface of the nanosub, powering it in the direction opposite to that of the flux of the hydronium. These nanosubmarines are responsive to external fields, able to follow complex magnetic patterns, navigate themselves in complex microfluidic channels, follow chemical gradients, carry cargo, and communicate with each other. This minireview focuses on a discussion of the fundamentals of the electrophoretic mechanism underlying the propulsion of this sort of nanosub, as well as a demonstration of the proof-of-concept capabilities of nanosubmarines.In the past few years, we have witnessed rapid developments in the realization of the old nanotechnology dream, autonomous nanosubmarines. These nanomachines are self-powered, taking energy from their environment by electrocatalytic conversion of chemicals present in the solution, self-propelled by flux of the electrons within the submarine and the hydronium ions on the surface of the nanosub, powering it in the direction opposite to that of the flux of the hydronium. These nanosubmarines are responsive to external fields, able to follow complex magnetic patterns, navigate themselves in complex microfluidic channels, follow chemical gradients, carry cargo, and communicate with each other. This minireview focuses on a discussion of the fundamentals of the electrophoretic mechanism underlying the propulsion of this sort of nanosub, as well as a demonstration of the proof-of-concept capabilities of nanosubmarines. In memory of Karel Zeman, Czech animator, who encouraged thousands of young people into science and technology, on the occasion of the 100th

  14. Electrophoretic molecular karyotype of the dermatophyte Trichophyton rubrum

    Directory of Open Access Journals (Sweden)

    Cervelatti Eliane P.


    Full Text Available The electrophoretic karyotype of the dermatophyte Trichophyton rubrum was established using contour-clamped homogeneous electric field (CHEF gel electrophoresis. Five chromosomal bands of approximately 3.0 to 5.8 megabase pairs (Mbp each were observed and together indicated that 22.05 Mbp of the total genome are organized as chromosomal macromolecules. In addition to establishing the number and size of T. rubrum chromosomes, these results open perspectives for the construction of chromosome-specific libraries and for the physical mapping of genes of interest, thus permitting future gene linkage studies in this pathogen. A detailed understanding of the karyotype and genomic organization of T. rubrum should contribute to further genetic, taxonomic and epidemiological studies of this dermatophyte.

  15. [Electron-microscopy studies of capillaries of the dialyser C-DAK 4 with reference to multiple use]. (United States)

    Stein, G; Linss, W; Völksch, G


    The results of the examinations show that the integrity of the wall of the capillary is not impaired by the process of purification, but, on the other hand, functional changes by thrombotic occlusion as well as disseminated deposits of protein may be expected. The temporary regime of dialysis mus consider this fact in order to achieve a constant effect. But on principle from the clinical experience and on the basis of these results of examinations a manifold use of the dialysator of the capillary in carrying out the purification measures mentioned may be recommended.

  16. Intramedullary capillary haemangioma.

    LENUS (Irish Health Repository)

    Kelleher, T


    Intramedullary capillary haemangioma is extremely rare and only four cases have been previously reported. We describe a further case, outlining the clinical, radiological, surgical and pathological features.

  17. [Improvement of carbohydrate deficient transferrin measurement by capillary zone electrophoresis using immunosubtraction of immunoglobulins and transferrin]. (United States)

    Baraud, J; Schellenberg, F; Pagès, J-C


    CDT (Carbohydrate Deficient Transferrin) is considered as the most efficient biomarker of alcohol abuse available for routine use. Among the various methods developed for its measurement, capillary zone electrophoresis (CZE) on the multicapillary analyzer Capillarys2 provides high quality results at high throughput. However, the non CDT specific measurement of protein absorbance at 200 nm may bring abnormal profiles in samples from patients with high polyclonal immunoglobulin level or monoclonal component. We evaluated the automated immunosubtraction procedure developed by the manufacturer in 48 samples with abnormal electrophoretic profiles that potentially could interfere with CZE measurement of CDT. Elimination of the serum immunoglobulins raised the number of interpretable profiles from 19 (40%) to 37 (77%). The immunosubtraction procedure failed in samples with a monoclonal component present at a concentration > 60 g/L and in some samples harbouring a partially degraded C3 fraction. Six samples identified as genetic BC transferrin variants were also included in the study and submitted to an automated transferrin subtraction procedure to ascertain whether the additional peak were actually transferrin glycoforms. After treatment, two samples were classified as homozygote C for transferrin due to the persistence of one of the supposed transferrin peak. In conclusion, immunoglobulin and transferrin subtraction allow a better CDT measurement in most samples with interfering monoclonal components and avoid misclassification of suspected transferrin BC or CD variants.

  18. Capillary electrophoresis separation of neutral organic compounds, pharmaceutical drugs, proteins and peptides, enantiomers, and anions

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Wei -Liang [Iowa State Univ., Ames, IA (United States)


    Addition of a novel anionic surfactant, namely lauryl polyoxyethylene sulfate, to an aqueous-acetonitrile electrolyte makes it possible to separate nonionic organic compounds by capillary electrophoresis. Separation is based on differences in the association between analytes and the surfactant. Highly hydrophobic compounds such as polyaromatic hydrocarbons are well separated by this new surfactant. Migration times of analytes can be readily changed over an unusually large range by varying the additive concentration and the proportion of acetonitrile in the electrolyte. Several examples are given, including the separation of four methylbenz[a]anthracene isomers and the separation of normal and deuterated acetophenone. The effect of adding this new surfactant to the acidic electrolyte was also investigated. Incorporation of cetyltrimethylammonium bromide in the electrolyte is shown to dynamically coat the capillary and reverse electroosmotic flow. Chiral recognition mechanism is studied using novel synthetic surfactants as chiral selectors, which are made from amino acids reacting with alkyl chloroformates. A satisfactory separation of both inorganic and organic anions is obtained using electrolyte solutions as high as 5 M sodium chloride using direct photometric detection. The effect of various salts on electrophoretic and electroosmotic mobility is further discussed. Several examples are given under high-salt conditions.

  19. Non-aqueous capillary electrophoresis of drugs: properties and application of selected solvents. (United States)

    Tjørnelund, J; Hansen, S H


    The electrophoretic mobility of selected acidic and basic test solutes have been determined in non-aqueous media prepared by adding various combinations of ammonium acetate, sodium acetate, methane sulphonic acid and acetic acid to acetonitrile, propylene carbonate, methanol, formamide, N-methylformamide, N,N-dimethylformamide and dimethylsulphoxide, respectively. The apparent pH (pH*) of these non-aqueous media have been measured and it was found that pH* is an important factor for the separations in non-aqueous capillary electrophoresis. However, in some solvents the concentration of sodium acetate has a strong influence on the mobility despite very small changes in pH*. Due to the fact that a change in one parameter influences a number of other parameters it is very difficult to conduct systematic studies in non-aqueous media and to compare the migration of the species at fixed pH* values from one solvent to another. Thus pH* is only of value for comparison when used with a specific solvent or solvent mixture. The viscosity of the above-mentioned solvents were measured at various temperatures and means to adjust the viscosity of the non-aqueous media used for capillary electrophoresis are discussed and the separation of ibuprofen and its major metabolites in urine is used as an example.

  20. Impacts on oil recovery from capillary pressure and capillary heterogeneities

    Energy Technology Data Exchange (ETDEWEB)

    Bognoe, Thomas


    The main conclusions drawn from this thesis are; 7 scientific papers are published on a broad variety of subjects, and describes in detail the experiments and research treated in this thesis. Scientific research has been performed, investigating the subjects of capillary pressure and capillary heterogeneities from different angles. This thesis discusses the findings in this study and aims to illustrate the benefits of the results obtained for further development of other experiments, and/or even the industrial benefits in field development. The methods for wettability alteration have developed throughout the work. From producing heterogeneous wettability alterations, the methods have improved to giving both radial and lateral uniform wettability alterations, which also remains unaltered throughout the duration of the experimental work. The alteration of wettability is dependent on initial water saturation, flow rate, aging time and crude oil composition. Capillary pressure and relative permeability curves have been measured for core plugs at different wettabilities using conventional centrifuge methods. The trends observed are mostly consistent with theory. The production mechanisms of strongly and moderately water wet chalk has been investigated. At strongly water wet conditions in fractured chalk; the flow is governed by capillary forces, showing strong impact from the fractures. At moderately water wet conditions, the impact of the fractures are absent, and a dispersed water front is observed during the displacement. The oil recovery is about the same, at the two wettabilities. Fracture crossing mechanisms at the same wettability conditions have been mapped. And the observations are consistent with those of the water floods. During strongly water wet displacement, the fracture crossing is occurring once the inlet core has reached endpoint of spontaneous imbibition. At moderately water wet conditions the fracture crossing is less abrupt, and creation of wetting

  1. Electrophoretic deposition of nickel zinc ferrite nanoparticles into microstructured patterns

    Directory of Open Access Journals (Sweden)

    Stefan J. Kelly


    Full Text Available Using DC electric fields, nickel-zinc ferrite (Ni0.5Zn0.5Fe2O4 nanoparticles (Dh =16.6 ± 3.6 nm are electrophoretically deposited onto silicon substrates to form dense structures defined by photoresist molds. Parameters such as electric field, bath composition, and deposition time are tuned to produce films ranging in thickness from 177 to 805 nm. The deposited films exhibit soft magnetic properties with a saturation magnetization of 60 emu/g and a coercivity of 2.6 kA/m (33 Oe. Additionally, the influence of the photoresist mold on the deposit profile is studied, and patterned films with different shapes (lines, squares, circles, etc. are demonstrated with feature sizes down to 5 μm.

  2. Design of colored multilayered electrophoretic particles for electronic inks. (United States)

    Badila, M; Hébraud, A; Brochon, C; Hadziioannou, G


    The preparation of multilayered latex particles with surface functional groups suitable for use as electrophoretic particles in electronic inks has been studied. The particles are formed by dispersion polymerization and have a polystyrene core, slightly cross-linked with divinylbenzene (DVB), and a poly(methyl methacrylate) (PMMA) or a poly(acrylic acid) (PAA) shell. After grafting alkyl chains on their surface, the particles are negatively or positively charged and sterically stabilized against aggregation in nonpolar solvent. The particles were dyed by incorporation of Nigrosin during polymerization or by swelling in supercritical CO(2) in the presence of a dye. Particle size, morphology, incorporated dye content and zeta potential were determined. A dual-particle electronic ink based on a mixture of the colored multilayered particles and white hybrid TiO(2)-polymer particles was prepared and electro-optically tested.

  3. Characterization and stability of gold nanoparticles depending on their surface chemistry: Contribution of capillary zone electrophoresis to a quality control. (United States)

    Pallotta, Arnaud; Boudier, Ariane; Leroy, Pierre; Clarot, Igor


    Four kinds of gold nanoparticles (AuNP) quite similar in terms of gold core size (ca. 5nm) and shape (spherical) but differing by their surface chemistry (either negatively, or positively charged, or neutral) were synthesized. They were analyzed using both the classical physicochemical approach (spectrophotometry, dynamic light scattering coupled or not to electrophoresis and transmission electron microscopy) and capillary zone electrophoresis equipped with photodiode array detection. The results obtained by both methodologies (related to Surface Plasmon Band-maximal absorbance wavelength-, and zeta potential and electrophoretic mobilities) were well correlated. Moreover, taking advantage of the separation method, the sample heterogeneity was evaluated and an impurity profile was extracted. This allowed setting some specifications which were then applied on the one hand to a batch-to-batch survey to declare NP as conform or not after production and on the other hand to a stability study.

  4. Evaluation of capillary zone electrophoresis for the determination of protein composition in therapeutic immunoglobulins and human albumins. (United States)

    Christians, Stefan; van Treel, Nadine Denise; Bieniara, Gabriele; Eulig-Wien, Annika; Hanschmann, Kay-Martin; Giess, Siegfried


    Capillary zone electrophoresis (CZE) provides an alternative means of separating native proteins on the basis of their inherent electrophoretic mobilities. The major advantage of CZE is the quantification by UV detection, circumventing the drawbacks of staining and densitometry in the case of gel electrophoresis methods. The data of this validation study showed that CZE is a reliable assay for the determination of protein composition in therapeutic preparations of human albumin and human polyclonal immunoglobulins. Data obtained by CZE are in line with "historical" data obtained by the compendial method, provided that peak integration is performed without time correction. The focus here was to establish a rapid and reliable test to substitute the current gel based zone electrophoresis techniques for the control of protein composition of human immunoglobulins or albumins in the European Pharmacopoeia. We believe that the more advanced and modern CZE method described here is a very good alternative to the procedures currently described in the relevant monographs.

  5. In situ delipidation of low-density lipoproteins in capillary electrochromatography yields apolipoprotein B-100-coated surfaces for interaction studies. (United States)

    D'Ulivo, Lucia; Chen, Jie; Meinander, Kristoffer; Oörni, Katariina; Kovanen, Petri T; Riekkola, Marja-Liisa


    An electrochromatographic method was developed for the in situ delipidation of intact low-density lipoprotein (LDL) particles immobilized on the inner wall of a 50-microm inner diameter silica capillary. In this method, the immobilized LDL particles were delipidated with nonionic surfactant Nonidet P-40 at pH 7.4 and 25 degrees C, resulting in an apolipoprotein B-100 (apoB-100)-coated capillary surface. The mobility of the electroosmotic flow marker dimethyl sulfoxide gave information about the surface charge, and the retention factors of beta-estradiol, testosterone, and progesterone were informative of the surface hydrophobicity. The calculated distribution coefficients of the steroids produced specific information about the affinity interactions of the steroids, with capillary surfaces coated either with intact LDL particles or with apoB-100. Delipidation with Nonidet P-40 resulted in a strong decrease in the hydrophobicity of the LDL coating. Atomic force microscopy images confirmed the loss of lipids from the LDL particles and the presence of apoB-100 protein coating. The in situ delipidation of LDL particles in capillaries represents a novel approach for the isolation of immobilized apoB-100 and for the determination of its pI value. The technique requires extremely low quantities of LDL particles, and it is simple and fast.

  6. Capillary based Li-air batteries for in situ synchrotron X-ray powder diffraction studies

    DEFF Research Database (Denmark)

    Storm, Mie Møller; Johnsen, Rune E.; Younesi, Reza;


    For Li-air batteries to reach their full potential as energy storage system, a complete understanding of the conditions and reactions in the battery during operation is needed. To follow the reactions in situ a capillary-based Li-O2 battery has been developed for synchrotron-based in situ X-ray p...

  7. Simulations of electrophoretic RNA transport through transmembrane carbon nanotubes. (United States)

    Zimmerli, Urs; Koumoutsakos, Petros


    The study of interactions between carbon nanotubes and cellular components, such as membranes and biomolecules, is fundamental for the rational design of nanodevices interfacing with biological systems. In this work, we use molecular dynamics simulations to study the electrophoretic transport of RNA through carbon nanotubes embedded in membranes. Decorated and naked carbon nanotubes are inserted into a dodecane membrane and a dimyristoylphosphatidylcholine lipid bilayer, and the system is subjected to electrostatic potential differences. The transport properties of this artificial pore are determined by the structural modifications of the membrane in the vicinity of the nanotube openings and they are quantified by the nonuniform electrostatic potential maps at the entrance and inside the nanotube. The pore is used to transport electrophoretically a short RNA segment and we find that the speed of translocation exhibits an exponential dependence on the applied potential differences. The RNA is transported while undergoing a repeated stacking and unstacking process, affected by steric interactions with the membrane headgroups and by hydrophobic interaction with the walls of the nanotube. The RNA is structurally reorganized inside the nanotube, with its backbone solvated by water molecules near the axis of the tube and its bases aligned with the nanotube walls. Upon exiting the pore, the RNA interacts with the membrane headgroups and remains attached to the dodecane membrane while it is expelled into the solvent in the case of the lipid bilayer. The results of the simulations detail processes of molecular transport into cellular compartments through manufactured nanopores and they are discussed in the context of applications in biotechnology and nanomedicine.

  8. Electrophoretic deposition of ultrasonicated and functionalized nanomaterials for multifunctional composites (United States)

    An, Qi

    Recent advances in the synthesis and characterization of nanostructured composite materials have enabled a broad range of opportunities for engineering the properties of polymer-matrix materials. Carbon nanotubes (CNTs) are known to have exceptional mechanical, electrical and thermal properties. Because of their small size, CNTs can occupy regions between traditional micro-scale reinforcements and create a hierarchical micro/nano structure spanning several orders of magnitude. Since CNTs possess critical reinforcement dimensions below 100 nm, new opportunities exist for tailoring the fiber/matrix interphase regions and ultimately the mechanical and electrical performance of advanced fiber-composites with minimal impact on the fiber-dominated properties. This growing interest in nanoscale hybridization with conventional fiber reinforcement has highlighted the need to develop new processing techniques for successful CNT integration. In this work, a novel and industrially scalable approach for producing multi-scale hybrid carbon nanotube/fiber composites using an electrophoretic deposition (EPD) technique has been studied as an alternative to in situ chemical vapor deposition growth (CVD). EPD is a widely used industrial coating process employed in areas ranging from automotive to electronics production. The method has a number of benefits which include low energy use and the ability to homogenously coat complex shapes with well adhered films of controlled thickness and density. A stable aqueous dispersion of multi-walled carbon nanotubes (MWCNTs) was produced using a novel ozonolysis and ultrasonication (USO) technique that results in dispersion and functionalization in a single step. Networks of CNTs span between adjacent fibers and the resulting composites exhibit significant increases in electrical conductivity and considerable improvements in the interlaminar shear strength and fracture toughness. In order to better understand the underlying mechanisms behind the

  9. Studies on multivalent interactions of quantum dots-protein self-assemble using fluorescence coupled capillary electrophoresis (United States)

    Wang, Jianhao; Li, Jingyan; Teng, Yiwan; Hu, Wei; Chai, Hong; Li, Jinchen; Wang, Cheli; Qiu, Lin; Jiang, Pengju


    Nanoparticle-biomolecules self-assembly is the key to the understanding of biomolecular coating of nanoparticle. However, the self-assembly of biomolecules with nanoparticles is still under-exploited because of the lack of an efficient method to detect the subtle changes in the surface of nanoparticles. In this study, we utilized fluorescence coupled capillary electrophoresis (CE-FL) to probe the binding interaction between a multivalent ligand (dBSA, denatured bovine serum albumin which contains multiple thiol groups) and CdSe/ZnS quantum dots (QDs, 5 nm in diameter). The yield of QDs-dBSA complex increased with increasing molar ratio of dBSA to QDs, which plateaued at a ratio of 8:1. Besides, QDs-dBSA complex showed good stability due to the multivalent interaction, revealing that dBSA is a superior ligand for QDs. The self-assembly kinetics of QDs with dBSA manifested a bi-phasic kinetics with a linear initial stage followed by a saturating stage. This work revealed for the first time that there exist two types of binding sites on the surface of QDs for dBSA: one type termed "high priority" binding sites, which preferentially bind to the protein, whereas the "low priority" sites are occupied only after the first-type binding sites are fully bound. Our work thereby represents the first example of systematic investigation on the details of the metal-affinity driven self-assembly between QDs and dBSA utilizing the high-resolution CE-FL. It also expanded the application of CE-FL in the study of nanoparticle-biomolecule interaction and kinetics analysis.

  10. Molecular Modeling Study of Chiral Separation and Recognition Mechanism of β-Adrenergic Antagonists by Capillary Electrophoresis

    Directory of Open Access Journals (Sweden)

    Yifeng Chai


    Full Text Available Chiral separations of five β-adrenergic antagonists (propranolol, esmolol, atenolol, metoprolol, and bisoprolol were studied by capillary electrophoresis using six cyclodextrins (CDs as the chiral selectors. Carboxymethylated-β-cyclodextrin (CM-β-CD exhibited a higher enantioselectivity power compared to the other tested CDs. The influences of the concentration of CM-β-CD, buffer pH, buffer concentration, temperature, and applied voltage were investigated. The good chiral separation of five β-adrenergic antagonists was achieved using 50 mM Tris buffer at pH 4.0 containing 8 mM CM-β-CD with an applied voltage of 24 kV at 20 °C. In order to understand possible chiral recognition mechanisms of these racemates with CM-β-CD, host-guest binding procedures of CM-β-CD and these racemates were studied using the molecular docking software Autodock. The binding free energy was calculated using the Autodock semi-empirical binding free energy function. The results showed that the phenyl or naphthyl ring inserted in the hydrophobic cavity of CM-β-CD and the side chain was found to point out of the cyclodextrin rim. Hydrogen bonding between CM-β-CD and these racemates played an important role in the process of enantionseparation and a model of the hydrogen bonding interaction positions was constructed. The difference in hydrogen bonding formed with the –OH next to the chiral center of the analytes may help to increase chiral discrimination and gave rise to a bigger separation factor. In addition, the longer side chain in the hydrophobic phenyl ring of the enantiomer was not beneficial for enantioseparation and the chiral selectivity factor was found to correspond to the difference in binding free energy.

  11. Pulsed lasers versus continuous light sources in capillary electrophoresis and fluorescence detection studies: Photodegradation pathways and models. (United States)

    Boutonnet, Audrey; Morin, Arnaud; Petit, Pierre; Vicendo, Patricia; Poinsot, Véréna; Couderc, François


    Pulsed lasers are widely used in capillary electrophoresis (CE) studies to provide laser induced fluorescence (LIF) detection. Unfortunately pulsed lasers do not give linear calibration curves over a wide range of concentrations. While this does not prevent their use in CE/LIF studies, the non-linear behavior must be understood. Using 7-hydroxycoumarin (7-HC) (10-5000 nM), Tamra (10-5000 nM) and tryptophan (1-200 μM) as dyes, we observe that continuous lasers and LEDs result in linear calibration curves, while pulsed lasers give polynomial ones. The effect is seen with both visible light (530 nm) and with UV light (355 nm, 266 nm). In this work we point out the formation of byproducts induced by pulsed laser upon irradiation of 7-HC. Their separation by CE using two Zeta LIF detectors clearly shows that this process is related to the first laser detection. All of these photodegradation products can be identified by an ESI-/MS investigation and correspond to at least two 7HC dimers. By using the photodegradation model proposed by Heywood and Farnsworth (2010) and by taking into account the 7-HC results and the fact that in our system we do not have a constant concentration of fluorophore, it is possible to propose a new photochemical model of fluorescence in LIF detection. The model, like the experiment, shows that it is difficult to obtain linear quantitation curves with pulsed lasers while UV-LEDs used in continuous mode have this advantage. They are a good alternative to UV pulsed lasers. An application involving the separation and linear quantification of oligosaccharides labeled with 2-aminobezoic acid is presented using HILIC and LED (365 nm) induced fluorescence.

  12. Sialic acid accelerates the electrophoretic velocity of injured dorsal root ganglion neurons

    Institute of Scientific and Technical Information of China (English)

    Chen-xu Li; Guo-ying Ma; Min-fang Guo; Ying Liu


    Peripheral nerve injury has been shown to result in ectopic spontaneous discharges on soma and injured sites of sensory neurons, thereby inducing neuropathic pain. With the increase of membrane proteins on soma and injured site neurons, the negatively charged sialic acids bind to the external domains of membrane proteins, resulting in an increase of this charge. We therefore speculate that the electrophoretic velocity of injured neurons may be faster than non-injured neurons. The present study established rat models of neuropathic pain via chronic constriction injury. Results of the cell electrophoresis test revealed that the electrophoretic velocity of injured neuronal cells was faster than that of non-injured (control) cells. We then treated cells with di-valent cations of Ca2+and organic compounds with positive charges, polylysine to counteract the negatively charged sialic acids, or neuraminidase to speciifcally remove sialic acids from the membrane surface of injured neurons. All three treatments significantly reduced the electro-phoretic velocity of injured neuronal cells. These ifndings suggest that enhanced sialic acids on injured neurons may accelerate the electrophoretic velocity of injured neurons.

  13. Sialic acid accelerates the electrophoretic velocity of injured dorsal root ganglion neurons

    Directory of Open Access Journals (Sweden)

    Chen-xu Li


    Full Text Available Peripheral nerve injury has been shown to result in ectopic spontaneous discharges on soma and injured sites of sensory neurons, thereby inducing neuropathic pain. With the increase of membrane proteins on soma and injured site neurons, the negatively charged sialic acids bind to the external domains of membrane proteins, resulting in an increase of this charge. We therefore speculate that the electrophoretic velocity of injured neurons may be faster than non-injured neurons. The present study established rat models of neuropathic pain via chronic constriction injury. Results of the cell electrophoresis test revealed that the electrophoretic velocity of injured neuronal cells was faster than that of non-injured (control cells. We then treated cells with divalent cations of Ca 2+ and organic compounds with positive charges, polylysine to counteract the negatively charged sialic acids, or neuraminidase to specifically remove sialic acids from the membrane surface of injured neurons. All three treatments significantly reduced the electrophoretic velocity of injured neuronal cells. These findings suggest that enhanced sialic acids on injured neurons may accelerate the electrophoretic velocity of injured neurons.

  14. Role of phospholipids in drug-LDL bindings as studied by high-performance frontal analysis/capillary electrophoresis. (United States)

    Kuroda, Yukihiro; Watanabe, Yoshinori; Shibukawa, Akimasa; Nakagawa, Terumichi


    The binding study between basic drugs ((S)-verapamil (VER) and (S)-propranolol (PRO)) and phospholipid liposomes was performed by using high-performance frontal analysis/capillary electrophoresis (HPFA/CE) in order to investigate the effect of oxidative modification of low-density lipoprotein (LDL) upon drug-binding affinity from molecule-based viewpoint. 1-Palmitoyl-2-oleoyl-phosphatidylcholine (POPC, 16:0, 18:1), 1-palmitoyl-2-linoleoyl-phosphatidylcholine (PLPC, 16:0, 18:2), dilauloyl-phosphatidylcholine (DLaPC, 12:0, 12:0), 1-palmitoyl-2-oleoyl-phosphatidyl-glycerol (POPG, 16:0, 18:1), and 1-palmitoyl-sn-glycero-3-phosphocholine (monoPPC, 16:0) were used to prepare the model liposomes. At physiological pH (pH 7.4), the model liposome prepared from POPG+POPC had negative net charges, while the total net charge of the other model liposomes (POPC liposome, PLPC liposome, DLaPC liposome, and monoPPC+POPC liposome) was zero. The drug and the model liposome mixed solutions were subjected to HPFA/CE, and the total binding affinities (nK) were calculated. The nK values of VER and PRO to POPG+POPC liposome were more than six and 10 times higher than those of other liposomes, respectively. On the other hand, the nK values of the model drugs to POPC liposome, PLPC liposome, DLaPC liposome and monoPPC+POPC liposome showed small differences less than twice. These results indicate that the electrostatic interaction plays an important effect on drug-liposome binding, and suggest that the increase in the negative charge of LDL phospholipids gives more significant effect on the drug-binding affinity of the basic drugs than the acyl-chain structure.

  15. Characterization and performance of a neutral hydrophilic coating for the capillary electrophoretic separation of biopolymers. (United States)

    Schmalzing, D; Piggee, C A; Foret, F; Carrilho, E; Karger, B L


    Polyvinylmethylsiloxanediol (50% vinyl) was synthesized and combined with a cross-linker for static coating onto fused-silica columns. After cross-linking and binding to the surface, linear polyacrylamide was grafted to the double bonds of the siloxanediol; subsequently, this linear polymer matrix was cross-linked with formaldehyde. The grafted neutral polymeric layer provided suppression of electroosmotic flow and minimized adsorption. This combination yielded successful open tube and polymer network separations of proteins, peptides and DNA molecules. Very high efficiencies (ca. 1 x 10(6) plates/m) were achieved for open tube protein separations, and hundreds of consecutive runs were performed with minimal change in migration times.

  16. Demonstrating Chemical and Analytical Concepts in the Undergraduate Laboratory Using Capillary Electrophoresis and Micellar Electrokinetic Chromatography (United States)

    Palmer, Christopher P.


    This paper describes instrumental analysis laboratory exercises that utilize capillary electrophoresis and micellar electrokinetic chromatography to demonstrate several analytical and chemical principles. Alkyl parabens (4-hydroxy alkyl benzoates), which are common ingredients in cosmetic formulations, are separated by capillary electrophoresis. The electrophoretic mobilities of the parabens can be explained on the basis of their relative size. 3-Hydroxy ethylbenzoate is also separated to demonstrate the effect of substituent position on the acid dissociation constant and the effect this has on electrophoretic mobility. Homologous series of alkyl benzoates and alkyl phthalates (common plasticizers) are separated by micellar electrokinetic chromatography at four surfactant concentrations. This exercise demonstrates the separation mechanism of micellar electrokinetic chromatography, the concept of chromatographic phase ratio, and the concepts of micelle formation. A photodiode array detector is used in both exercises to demonstrate the advantages and limitations of the detector and to demonstrate the effect of pH and substituent position on the spectra of the analytes.

  17. A Microfluidic Platform for Interfacial Electrophoretic Deposition (United States)

    Joung, Young Soo; Moran, Jeffrey; Jones, Andrew; Bailey, Eric; Buie, Cullen


    Composite membranes of hydrogel and carbon nanotubes (CNTs) are fabricated using electrophoretic deposition (EPD) at the interface of two immiscible liquids in microfluidic channels. Microfluidic channels, which have two parallel electrodes at the walls, are used to create electric fields across the interface of oil and water continuously supplied into the channels. Depending on the Reynolds (Re) and Weber (We) numbers of oil and water, we observe different formations of the interface. Once we find the optimal Re and We to create a planar interface in the channel, we apply an electric field across the interface for EPD of CNTs and/or silver (Ag) nanorods dispersed in water. During EPD, particles migrate to the oil/water interface, where cross-linking of polymers is induced to form composite hydrogel membranes. Properties of the composite hydrogel films are controlled by electric fields, CNT concentrations, and both Re and We numbers, allowing for continuous production. This fabrication method is effective to create composite polymer membranes placed in microfluidic devices with tunable electrical, mechanical, and biological properties. Potential applications include fabrication of doped hydrogels for drug delivery, conductive hydrogels for biological sensing, and electron permeable membranes for water splitting and osmotic power generation.

  18. Microencapsulated Electrophoretic Films for Electronic Paper Displays (United States)

    Amundson, Karl


    Despite the dominance of liquid crystal displays, they do not perform some functions very well. While backlit liquid crystal displays can offer excellent color performance, they wash out in bright lighting and suffer from high power consumption. Reflective liquid crystal displays have limited brightness, making these devices challenging to read for long periods of time. Flexible liquid crystal displays are difficult to manufacture and keep stable. All of these attributes (long battery lifetime, bright reflective appearance, compatibility with flexible substrates) are traits that would be found in an ideal electronic paper display - an updateable substitute for paper that could be employed in electronic books, newspapers, and other applications. I will discuss technologies that are being developed for electronic-paper-like displays, and especially on particle-based technologies. A microencapsulated electrophoretic display technology is being developed at the E Ink corporation. This display film offers offer high brightness and an ink-on-paper appearance, compatibility with flexible substrates, and image stability that can lead to very low power consumption. I will present some of the physical and chemical challenges associated with making display films with high performance.

  19. Fluid mechanics of electroosmotic flow and its effect on band broadening in capillary electrophoresis. (United States)

    Ghosal, Sandip


    Electroosmotic flow (EOF) usually accompanies electrophoretic migration of charged species in capillary electrophoresis unless special precautions are taken to suppress it. The presence of the EOF provides certain advantages in separations. It is an alternative to mechanical pumps, which are inefficient and difficult to build at small scales, for transporting reagents and analytes on microfluidic chips. The downside is that any imperfection that distorts the EOF profile reduces the separation efficiency. In this paper, the basic facts about EOF are reviewed from the perspective of fluid mechanics and its effect on separations in free solution capillary zone electrophoresis is discussed in the light of recent advances.

  20. DNA Sequencing Using capillary Electrophoresis

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Barry Karger


    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

  1. Enhanced electrophoretic motion using supercapacitor-based energy storage system. (United States)

    Liu, Ran; Wong, Flory; Duan, Wentao; Sen, Ayusman


    Electrophoretic motion at low potentials is facilitated by redox chemistry occurring in a supercapacitor-based electrochemical energy storage system during charge and discharge. We show that MnO2 -modified electrodes can effectively alleviate the electrode surface polarization, the main factor that leads to inefficient electrophoresis at low voltages. A self-powered electrophoretic system based on a discharging battery has been also fabricated.

  2. A Study of Ignition Effects on Thruster Performance of a Multi-Electrode Capillary Discharge Using Visible Emission Spectroscopy Diagnostics (United States)


    the housing, causing the temperature raise discussed in section 6.4, or as suggest here, reflects back into the plasma effect the discharge itself...achieve those conditions had little effects . The Paschen ignition method also worked well over a full range of capillary lengths. Paschen ignition...Ignited 6 cm 2500 V Is there a background pressure effect on measurements? Wire Spark Paschen higher di/dt at lower pressure Normalized Background

  3. Very small injected samples to study chloroquine and quinine in human serum using capillary-LC and native fluorescence


    Ibrahim, H.; Bouajila, J.; Siri, N.; Rozing, G.; Nepveu, Françoise; Couderc, F.


    A comparison between HPLC with conventional fluorescence detection and capillary-LC (mu HPLC) with native laser-induced fluorescence (LIF) detection was done to determine chloroquine (CQ) and quinine (Q) in human serum. HPLC experiments were run with parameters of the conventional fluorimeter set at the highest level of sensitivity. Results were compared with those obtained on mu HPLC coupled to a ZETALIF (He-Cd 325 nm) detector which provided a 50-fold increase in sensitivity. In mu HPLC-LIF...

  4. A method for studies on interactions between a gold-based drug and plasma proteins based on capillary electrophoresis with inductively coupled plasma mass spectrometry detection

    DEFF Research Database (Denmark)

    Nguyen, Tam T T N; Østergaard, Jesper; Gammelgaard, Bente


    An analytical method based on capillary electrophoresis (CE) and inductively coupled plasma mass spectrometry (ICP-MS) detection was developed for studies on the interaction of gold-containing drugs and plasma proteins using auranofin as example. A detection limit of 18 ng/mL of auranofin...... was the major auranofin-interacting protein in plasma. The CE-ICP-MS method is proposed as a novel approach for kinetic studies of the interactions between gold-based drugs and plasma proteins. Graphical Abstract Development of a CE-ICP-MS based method allows for studies on interaction of the gold containing...

  5. On-line immunoaffinity solid-phase extraction capillary electrophoresis mass spectrometry for the analysis of large biomolecules: a preliminary report. (United States)

    Medina-Casanellas, Silvia; Benavente, Fernando; Giménez, Estela; Barbosa, José; Sanz-Nebot, Victoria


    The analysis of large biomolecules by on-line immunoaffinity solid-phase extraction capillary electrophoresis mass spectrometry (IA-SPE-CE-MS) remains unexplored because of the complex issues that need to be addressed. In this preliminary study, we used the human glycoprotein transferrin (Tf) as a model of a large biomolecule. First, we established by CE-UV a novel method compatible with IA-SPE-CE-MS, based on the use of a fused silica capillary coated with an anionic derivative of polyacrylamide (UltraTrol(TM) Dynamic Pre-Coat High Normal, HN) to prevent protein adsorption. The methodology allowed the detection of the most abundant Tf sialoforms. Repeatability studies demonstrated high stability of the coated capillaries, which was required for on-line immunoextraction and MS detection. IA-SPE-CE-UV and IA-SPE-CE-MS methods were optimized for the analysis of Tf standards and human serum samples using a laboratory-made IA sorbent. Three peaks corresponding to Tf were detected with UV detection when on-line immunoextraction was applied to the standards. The use of MS detection, however, reduced the resolution of the electrophoretic separation. Finally, we demonstrated that it was possible to detect Tf in human serum samples, after off-line serum sample de-salting by centrifugal filtration.

  6. A High Voltage Power Supply That Mitigates Current Reversals in Capillary Zone Electrophoresis-Electrospray Mass Spectrometry (United States)

    Flaherty, Ryan J.; Sarver, Scott A.; Sun, Liangliang; Brownell, Greg A.; Go, David B.; Dovichi, Norman J.


    Capillary electrophoresis coupled with electrospray ionization typically employs two power supplies, one at each end of the capillary. One power supply is located at the proximal (injection) end of the capillary. The power supply located at the distal (detector) end of the capillary drives the electrospray. Electrophoresis is driven by the difference in potential between these power supplies. Separations that employ large capillary inner diameter, high conductivity background electrolyte, and high separation potentials generate higher current than that produced by the electrospray. Excess current flows through the electrospray power supply. Most power supplies are not designed to sink current, and the excess current will cause the electrospray voltage to deviate from its set point. We report a simple circuit to handle this excess current, allowing separations under a wide range of electrophoretic conditions.

  7. Pulsed lasers versus continuous light sources in capillary electrophoresis and fluorescence detection studies: Photodegradation pathways and models

    Energy Technology Data Exchange (ETDEWEB)

    Boutonnet, Audrey; Morin, Arnaud [Picometrics Technologies, 478 Rue de la Découverte, Labège France (France); Petit, Pierre [Institut de Mathématiques, Université de Toulouse, Université Paul Sabatier, Toulouse CEDEX 04 (France); Vicendo, Patricia; Poinsot, Véréna [Laboratoire des IMRCP, UMR 5623, Université de Toulouse, Université Paul Sabatier, Toulouse CEDEX 04 (France); Couderc, François, E-mail: [Laboratoire des IMRCP, UMR 5623, Université de Toulouse, Université Paul Sabatier, Toulouse CEDEX 04 (France)


    Pulsed lasers are widely used in capillary electrophoresis (CE) studies to provide laser induced fluorescence (LIF) detection. Unfortunately pulsed lasers do not give linear calibration curves over a wide range of concentrations. While this does not prevent their use in CE/LIF studies, the non-linear behavior must be understood. Using 7-hydroxycoumarin (7-HC) (10–5000 nM), Tamra (10–5000 nM) and tryptophan (1–200 μM) as dyes, we observe that continuous lasers and LEDs result in linear calibration curves, while pulsed lasers give polynomial ones. The effect is seen with both visible light (530 nm) and with UV light (355 nm, 266 nm). In this work we point out the formation of byproducts induced by pulsed laser upon irradiation of 7-HC. Their separation by CE using two Zeta LIF detectors clearly shows that this process is related to the first laser detection. All of these photodegradation products can be identified by an ESI-/MS investigation and correspond to at least two 7HC dimers. By using the photodegradation model proposed by Heywood and Farnsworth (2010) and by taking into account the 7-HC results and the fact that in our system we do not have a constant concentration of fluorophore, it is possible to propose a new photochemical model of fluorescence in LIF detection. The model, like the experiment, shows that it is difficult to obtain linear quantitation curves with pulsed lasers while UV-LEDs used in continuous mode have this advantage. They are a good alternative to UV pulsed lasers. An application involving the separation and linear quantification of oligosaccharides labeled with 2-aminobezoic acid is presented using HILIC and LED (365 nm) induced fluorescence. - Highlights: • No linear calibration curves are obtained in CE/Pulsed-LIF detection. • Photodegradation and photodimerisation are responsible of this non linearity. • A mathematical model of this phenomenon is presented. • 7 hydroxycoumarin in CE/LIF is used to verify the

  8. Capillary Optics generate stronger X-rays (United States)


    NASA scientist, in the Space Sciences lab at Marshall, works with capillary optics that generate more intense X-rays than conventional sources. This capability is useful in studying the structure of important proteins.

  9. Study of Gold Deposition on the Inner Wall of Quartz Capillary%石英毛细管内壁镀金工艺的研究

    Institute of Scientific and Technical Information of China (English)

    王梦兰; 贾法龙; 张礼知


    ABSTRACT:Objective To develop feasible gold deposition technology on the inner wall of the quartz capillary, which is used for gas detection and analysis by laser Raman. Methods Gold plating was studied with quartz glass first and an optimal technology was achieved after the determination of condition parameters for hydroxylation, silanization, gold nanoparticles modification and wet plating. Then this process was applied to the quartz capillary after adjustment of relevant parameters. The gilded quartz capillary was used for gas analysis through laser Raman measurements, and the enhancement effect of scattering signals was analyzed. Re-sults The concentration of sodium hydroxide, the flow rate and flow time of solution in the capillary obviously affected the adsorption of gold nanoparticles. The optimal technology for gold plating inside the quartz capillary was as following:5 mol/L NaOH treatment for 1 minˇAPTMS/IPA alkylated modificationˇgold sol process at the flow rate of 0. 8 mL/min for 4 h ˇtreatment with plating liquid containing hydroxylamine hydrochloride for 4 h at the flow rate of 0. 8 mL/min. The gilded capillary was used for gas Raman tests and the relative peak strength of N2 in the air was increased from 148 counts ( without gold plating) to 480 counts. Conclu-sion By the use of gold-deposited quartz capillary, corresponding signals of gas could be effectively enhanced under laser Raman detection, which lays a foundation for the further in-situ Raman analysis of gas.%目的:开发出切实可行的石英毛细管内壁镀金工艺,应用于激光拉曼的气体分析检测中。方法先用石英玻璃片进行镀金工艺研究,经过对羟基化、硅烷化、纳米金颗粒修饰、湿法镀金各步条件参数的确定,获得最佳的镀金工艺方案,再对相关参数进行调整,应用于石英毛细管。将镀金石英毛细管应用于激光拉曼的气体分析测试中,分析其对散射


    Directory of Open Access Journals (Sweden)

    Edward Pospiech


    Full Text Available Electrophoretic methods can be used to identify meat of various animal species. The protein electrophoresis, especially the IEF of the sarcoplasmic proteins, is a well-established technique for species identification of raw fish and is used in the control of seafood authenticity. However, in the case of the analysis of heat-processed fish, the method is applicable only to those species which possess characteristic patterns of the heat-stable parvalbumins. Heat-denatured fish muscle proteins may be solubilised by urea or sodium dodecylsulfate (SDS and separated by urea-IEF or SDS-PAGE, respectively. The comparison of these two methods allowed to conclude that, basically, each of them can be used for species identification of heated fishery products. However, extensively washed products may be preferentially analysed by the SDS-PAGE, because most of the parvalbumins are washed out leaving mainly myosins. On the other hand, the IEF method may be preferred for the differentiation of closely related species rich in parvalbumins isoforms. It is evident from the literature data that species-specific protein separations yield proteins of low molecular weight made up of three light chains of myosin (14-23 kDa, troponin (19-30 kDa and parvalbumin (about 12 kDa. Investigations showed that the SDS-PAGE method can be used to identify meats of: cattle, sheep, lambs, goats, red deer and rabbits. The technique allowed researchers to identify the following myofibrillar and sarcoplasmic muscle proteins: myosin and actin, α-actinin, tropomyosin, troponin. SDS-PAGE allowed the identification of myofibrillar proteins taking into account their molecular weights which was not possible with the assistance of the PAGIF because too many protein bands were obtained. It was possible to obtain differences in the separation of proteins characteristic for certain species, e.g. beef, resulting from the presence of sin-gle myofibrillar proteins.

  11. Capillary Electrophoresis for the Simultaneous Determination of Metals by Using Ethylenediamine Tetraacetic Acid as Complexing Agent and Vancomycin as Complex Selector

    Institute of Scientific and Technical Information of China (English)

    THREEPROM, Jirasak; SOM-AUM, Waraporn; LIN, Jin-Ming


    A new separation system of capillary electrophoresis for the simultaneous determination of metals by using ethylenediamine tetraacetic acid (EDTA) as complexing agent and employing vancomycin as complex selector was described. The Z-shape cell capillary electrophoresis was used to enhance the sensitivity for the determination of the complexes of Cu(Ⅱ), Ni(Ⅱ), Co(Ⅱ) and Fe(Ⅲ) with EDTA. The partial filling method (co-current mode) was used in order to increase the selectivity of the electrophoretic method, meanwhile vancomycin was not present at the detector path during the detection of metal-EDTA complexes. The vancomycin concentration, phosphate concentration and pH of the buffer strongly influenced mobility, resolution and selectivity of the studied analytes. Under the optimal condition, the relative standard deviations (n=5) of the migration time and the peak area were less than 3.14% and 7.35%, respectively. Application of the Z-shape cell capillary electrophoresis method with UV detection and vancomycin loading led to the reliable determination of these metal ions in tap water and the recoveries were 97%-101%. The detection limits based on a signal to noise ratio of 3: 1 were found in the range of 2-10 μg·L-1.

  12. Ultrasound-assisted magnetic solid-phase extraction for the determination of some transition metals in Orujo spirit samples by capillary electrophoresis. (United States)

    Peña Crecente, Rosa M; Lovera, Carlha Gutiérrez; García, Julia Barciela; Latorre, Carlos Herrero; Martín, Sagrario García


    Ultrasound-assisted magnetic solid-phase extraction coupled to capillary electrophoresis was optimized for the preconcentration and determination of Zn(II), Cu(II), Mn(II) and Cd(II) as their complexes with 1,10-phenanthroline (Phen). Both pre- and on-capillary complexations were employed to obtain stable metal-Phen complexes. The parameters that have an influence on the electrophoretic separation and the MSPE process were studied and optimized using different experimental designs. Metals were extracted from 10 mL of sample at pH 5 using 3mg of magnetic particles functionalized with carboxylic groups. The metals were eluted as metal-Phen complexes and analyzed by capillary electrophoresis. The method showed low limits of detection for metals 0.49-2.19 μg L(-1), and high preconcentration factors, 39-44, The efficiencies of the extraction method were in the range 77.1-87.5% and the precision (RSD < 10%) and accuracy were between 98.2% and 101.6%. The method was applied to the determination of the aforementioned metals in Galician Orujo spirit samples.

  13. Interconverting conformations of variants of the human amyloidogenic protein beta2-microglobulin quantitatively characterized by dynamic capillary electrophoresis and computer simulation

    DEFF Research Database (Denmark)

    Heegaard, Niels H H; Jørgensen, Thomas J D; Cheng, Lei


    Capillary electrophoretic separation profiles of cleaved variants of beta2-microglobulin (beta2m) reflect the conformational equilibria existing in solutions of these proteins. The characterization of these equilibria is of interest since beta2m is responsible for amyloid formation in dialysis-re...

  14. Study of capillary absorption kinetics by X-ray CT imaging techniques: a survey on sedimentary rocks of Sicily

    Directory of Open Access Journals (Sweden)

    Tiziano Schillaci


    Full Text Available Sedimentary rocks are natural porous materials with a great percent of microscopic interconnected pores: they contain fluids, permitting their movement on macroscopic scale. Generally, these rocks present porosity higher then metamorphic rocks. Under certain points of view, this feature represents an advantage; on the other hand, this can constitute an obstacle for cultural heritage applications, because the porosity grade can lead to a deterioration of the lapideous monument for water capillary absorption. In this paper, CT (Computerized Tomography image techniques are applied to capillary absorption kinetics in sedimentary rocks utilized for the Greek temples as well as baroc monuments, respectively located in western and southeastern Sicily. Rocks were sampled near the archaeological areas of Agrigento, Segesta, Selinunte and Val di Noto. CT images were acquired at different times, before and after the water contact, using image elaboration techniques during the acquisition as well as the post-processing phases. Water distribution into porous spaces has been evaluated on the basis of the Hounsfield number, estimated for the 3-D voxel structure of samples. For most of the considered samples, assumptions based on Handy model permit to correlate the average height of the wetting front to the square root of time. Stochastic equations were introduced in order to describe the percolative water behavior in heterogeneous samples, as the Agrigento one. Before the CT acquisition, an estimate of the capillary absorption kinetics has been carried out by the gravimetric method. A petrographical characterization of samples has been performed by stereomicroscope observations, while porosity and morphology of porous have been surveyed by SEM (Scanning Electron Microscope images. Furthermore, the proposed methods have also permitted to define penetration depth as well as distribution uniformity of materials used for restoration and conservation of historical

  15. Determination of pKa values of tenoxicam from 1H NMR chemical shifts and of oxicams from electrophoretic mobilities (CZE) with the aid of programs SQUAD and HYPNMR. (United States)

    Rodríguez-Barrientos, Damaris; Rojas-Hernández, Alberto; Gutiérrez, Atilano; Moya-Hernández, Rosario; Gómez-Balderas, Rodolfo; Ramírez-Silva, María Teresa


    In this work it is explained, by the first time, the application of programs SQUAD and HYPNMR to refine equilibrium constant values through the fit of electrophoretic mobilities determined by capillary zone electrophoresis experiments, due to the mathematical isomorphism of UV-vis absorptivity coefficients, NMR chemical shifts and electrophoretic mobilities as a function of pH. Then, the pK(a) values of tenoxicam in H(2)O/DMSO 1:4 (v/v) have been obtained from (1)H NMR chemical shifts, as well as of oxicams in aqueous solution from electrophoretic mobilities determined by CZE, at 25 degrees C. These values are in very good agreement with those reported by spectrophotometric and potentiometric measurements.

  16. Study of thermal performance of capillary micro tubes integrated into the building sandwich element made of high performance concrete

    DEFF Research Database (Denmark)

    Mikeska, Tomas; Svendsen, Svend


    The thermal performance of radiant heating and cooling systems (RHCS) composed of capillary micro tubes (CMT) integrated into the inner plate of sandwich elements made of high performance concrete (HPC) was investigated in the article. Temperature distribution in HPC elements around integrated CMT...... HPC layer covering the CMT. This paper shows that CMT integrated into the thin plate of sandwich element made of HPC can supply the energy needed for heating (cooling) and at the same time create the comfortable and healthy environment for the occupants. This solution is very suitable for heating...

  17. A comparative study of capillary zone electrophoresis and pH-potentiometry for determination of dissociation constants. (United States)

    Andrasi, Melinda; Buglyo, Peter; Zekany, Laszlo; Gaspar, Attila


    Acidity constants of six cephalosporin antibiotics, cefalexin, cefaclor, cefadroxil, cefotaxim, cefoperazon and cefoxitin are determined using capillary zone electrophoresis (CZE) and pH-potentiometric titrations. Since CZE is a separation method, it is not necessary for the samples to be of high purity and known concentration because only mobilities are measured. The effect on determination of dissociation constants of different matrices (serum, 0.9% NaCl, fermentation matrix) was examined. The advantages of CZE can be utilized in those fields where potentiometry has limitations (sample quantity, solubility, purity, simultaneous determinations), although pK(a) values that are close to each other can be determined by potentiometry with more accuracy.

  18. Study of Competitive Chelating Reaction between Lanthanum and Tribromoarsenazo in the Medium of Weak Acid by Capillary Zone Electrophoresis

    Institute of Scientific and Technical Information of China (English)

    胡涌刚; 周培疆; 邓延倬; 程介克


    Two kinds of metal chelates of rare earth elements reacted with tribrimoarsenazo formed under the condition of critic acid were observed by simultaneous technique of capillary electrophoresisphotothermal interference spectrometry. The tendency of the conversion between these chelates as functions of the mole ratio of the reagent and the metal, pH value and the elapsing time was investigated. Kinetic equation of competitive chelating reaction between the TBA-La (Ⅲ) and La (Ⅲ) -critic acid were established. It was found that the competitive chelating reaction follows secondorder kinetics, for this second-order reaction, k=5.55 L·mol-1·S-1.

  19. Experimental study of a water thermo-capillary loop; Etude experimentale d`une boucle thermocapillaire a eau

    Energy Technology Data Exchange (ETDEWEB)

    Lefriec, C.; Alexandre, A. [Ecole Nationale Superieure de Mecanique et d`Aerotechnique (ENSMA), 86 - Poitiers (France)


    This paper presents a bench scale experiment of a water thermo-capillary loop which allows to improve the understanding of its functioning mechanisms thanks to the internal visualisation of each component using transparent walls. The advantages of water are its non-toxicity, its high chemical compatibility with several materials and its low functioning pressure. The experimental device is presented and the functioning regimes of each component is analyzed: condenser (flow visualization, influence of tilt), evaporator (quality of heat exchange between teeth and porous medium, bubbles, heat exchange coefficient). (J.S.)

  20. Unusual intraosseous capillary hemangioma of the mandible. (United States)

    Dereci, Omur; Acikalin, Mustafa Fuat; Ay, Sinan


    Intraosseous hemangioma is a benign vascular neoplasm, which is mostly seen in vertebrae, maxillofacial bones, and long bones. Intraosseous hemangioma is rarely seen on jaw bones compared to other skeletal bones and usually occurs in the cavernous form. Capillary intraosseous hemangioma of jaws is an uncommon form of intraosseous hemangioma and has not been thoroughly described so far. In this study, a case of capillary intraosseous hemangioma of the mandible was presented with relevant literature review.

  1. Unusual intraosseous capillary hemangioma of the mandible


    Dereci, Omur; Acikalin, Mustafa Fuat; Ay, Sinan


    Intraosseous hemangioma is a benign vascular neoplasm, which is mostly seen in vertebrae, maxillofacial bones, and long bones. Intraosseous hemangioma is rarely seen on jaw bones compared to other skeletal bones and usually occurs in the cavernous form. Capillary intraosseous hemangioma of jaws is an uncommon form of intraosseous hemangioma and has not been thoroughly described so far. In this study, a case of capillary intraosseous hemangioma of the mandible was presented with relevant liter...

  2. Effect of size, quaternary structure and translational error on the static and dynamic heterogeneity of beta-galactosidase and measurement of electrophoretic dynamic heterogeneity. (United States)

    Craig, Douglas B; Haslam, Allison M; Silverstein, Harlyn J; Chikamatsu, Miki; Shadabi, Elnaz; Nichols, Ellert R


    Single enzyme molecule assays were performed using capillary electrophoresis-based protocols on beta-galactosidase from Lactobacillus delbrueckii, Lactobacillus reuteri, Lactobacillus helveticus and Bacillus circulans. The enzyme was found to show static heterogeneity with respect to catalytic rate and the variance in rate increased with protein size. This is consistent with the proposal that random errors in translation may be an important underlying component of enzyme heterogeneity. Additionally these enzymes were found to show static heterogeneity with respect to electrophoretic mobility. Comparison of wild-type and rpsL E. coli beta-galactosidase expressed in the presence and absence of streptomycin suggested that increases in error do not result in detectable increases in the dynamic heterogeneity of activity with increasing temperature. Finally, a method was developed to measure the dynamic heterogeneity in electrophoretic mobility.

  3. Mixed Capillary Venous Retroperitoneal Hemangioma

    Directory of Open Access Journals (Sweden)

    Mohit Godar


    Full Text Available We report a case of mixed capillary venous hemangioma of the retroperitoneum in a 61-year-old man. Abdominal ultrasonography showed a mass to be hypoechoic with increased flow in color Doppler imaging. Dynamic contrast-enhanced computed tomography revealed a centripetal filling-in of the mass, located anterior to the left psoas muscle at the level of sacroiliac joint. On the basis of imaging features, preoperative diagnosis of hemangioma was considered and the mass was excised by laparoscopic method. Immunohistochemical studies were strongly positive for CD31 and CD34, and negative for calretinin, EMA, WT1, HMB45, Ki67, synaptophysin, and lymphatic endothelial cell marker D2–40. Histologically, the neoplasm was diagnosed as mixed capillary venous hemangioma.

  4. Membrane diffusion- and capillary blood volume measurements are not useful as screening tools for pulmonary arterial hypertension in systemic sclerosis: a case control study

    Directory of Open Access Journals (Sweden)

    Spreeuwenberg Marieke D


    Full Text Available Abstract Background There is no optimal screening tool for the assessment of pulmonary arterial hypertension (PAH in patients with systemic sclerosis (SSc. A decreasing transfer factor of the lung for CO (TLCO is associated with the development of PAH in SSc. TLCO can be partitioned into the diffusion of the alveolar capillary membrane (Dm and the capillary blood volume (Vc. The use of the partitioned diffusion to detect PAH in SSc is not well established yet. This study evaluates whether Dm and Vc could be candidates for further study of the use for screening for PAH in SSc. Methods Eleven SSc patients with PAH (SScPAH+, 13 SSc patients without PAH (SScPAH- and 10 healthy control subjects were included. Pulmonary function testing took place at diagnosis of PAH. TLCO was partitioned according to Roughton and Forster. As pulmonary fibrosis in SSc influences values of the (partitioned TLCO, these were adjusted for fibrosis score as assessed on HRCT. Results TLCO as percentage of predicted (% was lower in SScPAH+ than in SScPAH- (41 ± 7% vs. 63 ± 12%, p vs. 39 ± 12%, p Conclusion SScPAH+ patients have lower Dm% than SScPAH- patients. There are no correlations between Dm% and hemodynamic parameters of PAH in SScPAH+. These findings do not support further study of the role of partitioning TLCO in the diagnostic work- up for PAH in SSc.

  5. Capillary electromigration techniques as tools for assessing the status of vitamins A, C and E in patients with cystic fibrosis. (United States)

    Olędzka, Ilona; Kaźmierska, Katarzyna; Plenis, Alina; Kamińska, Barbara; Bączek, Tomasz


    The purpose of this work is the evaluation of the nutritional status of patients with cystic fibrosis (CF), based on the level of vitamin C in urine and vitamins A and E in serum, using the fast, selective and fully automated micellar electrokinetic capillary chromatographic (MEKC) and microemulsion electrokinetic capillary chromatographic (MEEKC) methods. The optimization of parameters affecting the electrophoretic separation provided adequate separation of the analytes of interest in the short time of 8 min (MEKC) and 20 min (MEEKC). The developed methods were practical applications to evaluate the levels of vitamins A, C and E in real samples from 28 children suffering from cystic fibrosis and from 10 healthy volunteers. Based on the mean concentration values obtained in the two groups, it can be seen that the levels of each vitamin were lower in patients with CF than in healthy volunteers. In the case of vitamin E, these differences in both groups were statistically significant, while the disproportion of concentrations of vitamins A and C in both the studied groups were not so relevant. On the other hand, a principal component analysis (PCA) confirmed that in some patients with CF the concentration of vitamin A was significantly lower than in the control group. Thus, the future evaluation of the status of fat-soluble vitamins in the longer term for the evaluation of the nutritional status of patients with CF should be continued. The presented CE methods can become useful tools for the evaluation of the nutritional status of patients with CF.

  6. [Morphometry and electrophoretic mobility of red blood cells from patients with asthma in the intravenous blood laser irradiation]. (United States)

    Sarycheva, T G; Tsybzhitova, E B; Popova, O V; Aleksandrov, O V


    The morphometry and electrophoretic mobility of red blood cells from patients with infection-dependent asthma were comparatively studied prior to and following treatment. The patients who had underwent intravenous laser irradiation of blood (ILIB) in addition to conventional therapy had better morphofunctional parameters of red blood cells, by restoring their normal forms, decreasing their transitional ones, and increasing their electrophoretic mobility to normal values. Those who received traditional drug therapy showed no considerable morphofunctional changes of erythrocytes. Thus, in asthmatic patients, the changes in the morphology and function of red blood cells may suggest their membranous structural changes for whose correction ILIB should used.

  7. Comparative study of multi walled carbon nanotubes-based electrodes in micellar media and their application to micellar electrokinetic capillary chromatography. (United States)

    Chicharro, Manuel; Arribas, Alberto Sánchez; Moreno, Mónica; Bermejo, Esperanza; Zapardiel, Antonio


    This work reports on a comparative study of the electrochemical performance of carbon nanotubes-based electrodes in micellar media and their application for amperometric detection in micellar electrokinetic capillary chromatography (MEKC) separations. These electrodes were prepared in two different ways: immobilization of a layer of carbon nanotubes dispersed in polyethylenimine (PEI), ethanol or Nafion onto glassy carbon electrodes or preparation of paste electrodes using mineral oil as binder. Scanning electron microscopy (SEM) was employed for surface morphology characterization while cyclic voltammetry of background electrolyte was used for capacitance estimation. The amperometric responses to hydrogen peroxide, amitrol, diuron and 2,3-dichlorophenol (2,3CP) in the presence and in the absence of sodium dodecylsulphate (SDS) were studied by flow injection analysis (FIA), demonstrating that the electrocatalytic activity, background current and electroanalytical performance were strongly dependent on the electrodes preparation procedure. Glassy carbon electrodes modified with carbon nanotubes dispersed in PEI (GC/(CNT/PEI)) displayed the most adequate performance in micellar media, maintaining good electrocatalytic properties combined with acceptable background currents and resistance to passivation. The advantages of using GC/(CNT/PEI) as detectors in capillary electrophoresis were illustrated for the MEKC separations of phenolic pollutants (phenol, 3-chlorophenol, 2,3-dichlorophenol and 4-nitrophenol) and herbicides (amitrol, asulam, diuron, fenuron, monuron and chlortoluron).

  8. Gas-Filled Capillary Model (United States)

    Steinhauer, L. C.; Kimura, W. D.


    We have developed a 1-D, quasi-steady-state numerical model for a gas-filled capillary discharge that is designed to aid in selecting the optimum capillary radius in order to guide a laser beam with the required intensity through the capillary. The model also includes the option for an external solenoid B-field around the capillary, which increases the depth of the parabolic density channel in the capillary, thereby allowing for propagation of smaller laser beam waists. The model has been used to select the parameters for gas-filled capillaries to be utilized during the Staged Electron Laser Acceleration — Laser Wakefield (STELLA-LW) experiment.

  9. Design and operation of a portable scanner for high performance microchip capillary array electrophoresis. (United States)

    Scherer, James R; Liu, Peng; Mathies, Richard A


    We have developed a compact, laser-induced fluorescence detection scanner, the multichannel capillary array electrophoresis portable scanner (McCAEPs) as a platform for electrophoretic detection and control of high-throughput, integrated microfluidic devices for genetic and other analyses. The instrument contains a confocal optical system with a rotary objective for detecting four different fluorescence signals, a pneumatic system consisting of two pressure/vacuum pumps and 28 individual addressable solenoid valves for control of on-chip microvalves and micropumps, four Polymerase Chain Reaction (PCR) temperature control systems, and four high voltage power supplies for electrophoresis. The detection limit of the instrument is ~20 pM for on-chip capillary electrophoresis of fluorescein dyes. To demonstrate the system performance for forensic short tandem repeat (STR) analysis, two experiments were conducted: (i) electrophoretic separation and detection of STR samples on a 96-lane microfabricated capillary array electrophoresis microchip. Fully resolved PowerPlex(®) 16 STR profiles amplified from 1 ng of 9947A female standard DNA were successfully obtained; (ii) nine-plex STR amplification, sample injection, separation, and fluorescence detection of 100-copy 9948 male standard DNA in a single integrated PCR- capillary electrophoresis microchip. These results demonstrate that the McCAEPs can be used as a versatile control and detection instrument that operates integrated microfluidic devices for high-performance forensic human identification.

  10. Capillary Electrophoresis - Optical Detection Systems

    Energy Technology Data Exchange (ETDEWEB)

    Sepaniak, M. J.


    Molecular recognition systems are developed via molecular modeling and synthesis to enhance separation performance in capillary electrophoresis and optical detection methods for capillary electrophoresis. The underpinning theme of our work is the rational design and development of molecular recognition systems in chemical separations and analysis. There have been, however, some subtle and exciting shifts in our research paradigm during this period. Specifically, we have moved from mostly separations research to a good balance between separations and spectroscopic detection for separations. This shift is based on our perception that the pressing research challenges and needs in capillary electrophoresis and electrokinetic chromatography relate to the persistent detection and flow rate reproducibility limitations of these techniques (see page 1 of the accompanying Renewal Application for further discussion). In most of our work molecular recognition reagents are employed to provide selectivity and enhance performance. Also, an emerging trend is the use of these reagents with specially-prepared nano-scale materials. Although not part of our DOE BES-supported work, the modeling and synthesis of new receptors has indirectly supported the development of novel microcantilevers-based MEMS for the sensing of vapor and liquid phase analytes. This fortuitous overlap is briefly covered in this report. Several of the more significant publications that have resulted from our work are appended. To facilitate brevity we refer to these publications liberally in this progress report. Reference is also made to very recent work in the Background and Preliminary Studies Section of the Renewal Application.

  11. Capillary stretching of elastic fibers (United States)

    Protiere, Suzie; Stone, Howard A.; Duprat, Camille


    Fibrous media consisting of constrained flexible fibers can be found in many engineered systems (membranes in filters, woven textile, matted paper). When such materials interact with a liquid, the presence of liquid/air interfaces induces capillary forces that deform the fibers. To model this interaction we study the behaviour of a finite volume of liquid deposited on two parallel flexible fibers clamped at both ends. A tension along the fibers is imposed and may be varied. We show that the system undergoes various morphological changes as the interfiber distance, the elasticity and the tension of the fibers are varied. For a certain range of parameters, the liquid spreads along the fibers and pulls them together, leading to the ``zipping'' of the fibers. This capillary adhesion can then be enhanced or reduced by changing the tension within the fibers. We will show that balancing stretching and capillary forces allows the prediction of this transition as well as the conditions for which detachment of the fibers occurs. These results may be used to prevent the clogging of fibrous membranes or to optimize the capture of liquids.

  12. Modified monolithic silica capillary for preconcentration of catecholamines

    Institute of Scientific and Technical Information of China (English)

    Wei Chang; Tusyo-shi Komazu


    Preconcentration of catecholamines by the modified monolithic silica in the capillary was investigated in this study. In order to achieve a microchip-based method for determining catecholamines in the saliva, the monolithic silica was fabricated in the capillary and the monolithic silica was chemically modified by on-column reaction with phenylboronate. Different modified methods were compared. The concentration conditions were optimized. This study indicates the applicability of the modified monolithic silica capillary when it was used to concentrate catecholamines.

  13. An improved driving waveform reference grayscale of electrophoretic displays (United States)

    Wang, Li; Yi, Zichuan; Peng, Bao; Zhou, Guofu


    Driving waveform is an important component for gray scale display on the electrophoretic display (EPD). In the traditional driving waveform, a white reference gray scale is formed before writing a new image. However, the reflectance value can not reach agreement in each gray scale transformation. In this paper, a new driving waveform, which has a short waiting time after the formation of reference gray scale, is proposed to improve the consistency of reference gray scale. Firstly, the property of the particles in the microcapsule is analyzed and the change of the EPD reflectance after the white reference gray scale formation is studied. Secondly, the reflectance change curve is fitted by using polynomial and the duration of the waiting time is determined. Thirdly, a set of the new driving waveform is designed by using the rule of DC balance and some real E-ink commercial EPDs are used to test the performance. Experimental results show that the effect of the new driving waveform has a better performance than traditional waveforms.

  14. Derivatization in Capillary Electrophoresis. (United States)

    Marina, M Luisa; Castro-Puyana, María


    Capillary electrophoresis is a well-established separation technique in analytical research laboratories worldwide. Its interesting advantages make CE an efficient and potent alternative to other chromatographic techniques. However, it is also recognized that its main drawback is the relatively poor sensitivity when using optical detection. One way to overcome this limitation is to perform a derivatization reaction which is intended to provide the analyte more suitable analytical characteristics enabling a high sensitive detection. Based on the analytical step where the CE derivatization takes place, it can be classified as precapillary (before separation), in-capillary (during separation), or postcapillary (after separation). This chapter describes the application of four different derivatization protocols (in-capillary and precapillary modes) to carry out the achiral and chiral analysis of different compounds in food and biological samples with three different detection modes (UV, LIF, and MS).

  15. How Capillary Rafts Sink

    CERN Document Server

    Protiere, S; Aristoff, J; Stone, H


    We present a fluid dynamics video showing how capillary rafts sink. Small objects trapped at an interface are very common in Nature (insects walking on water, ant rafts, bubbles or pollen at the water-air interface, membranes...) and are found in many multiphase industrial processes. Thanks to Archimedes principle we can easily predict whether an object sinks or floats. But what happens when several small particles are placed at an interface between two fluids. In this case surface tension also plays an important role. These particles self-assemble by capillarity and thus form what we call a "capillary raft". We show how such capillary rafts sink for varying sizes of particles and define how this parameter affects the sinking process.

  16. A Theoretical Study of Steady State and Transient Condensation on Axisymmetric Fins Under Combined Capillary and Gravitational Forces (United States)

    Kostoglou, M.; Karapantsios, T. D.; Buffone, C.; Glushchuk, A.; Iorio, C.


    The present work attempts to model the case of combined gravitational and capillary motion of condensate for an axisymmetric fin under steady and transient fin operation conditions. The focus here is to examine the structure of the mathematical problem and to develop suitable numerical techniques rather than yield information on the macroscopic condensate flow rate and fin efficiency. The problem is formulated starting from general conditions and is simplified step by step by introducing corresponding assumptions. The particular fin shape of a paraboloid from revolution is chosen and the equations are properly non-dimensionalized. A vast reduction of the number of problem parameters is achieved in this way. The cases of isothermal fin, steady state operation and dynamic operation are treated separately using specialized numerical solution techniques developed for each case in order to improve computational efficiency and accuracy. Typical results of fin temperature and condensate film thickness are presented and discussed.

  17. Migration behavior of alkylphenols, bisphenol A and bisphenol S studied by capillary electrophoresis using sulfated beta-cyclodextrin. (United States)

    Mori, M; Naraoka, H; Tsue, H; Morozumi, T; Kaneta, T; Tanaka, S


    An application of capillary electrophoresis (CE) using sulfated beta-cyclodextrin (SCD) has been investigated for separating alkylphenols with different chain lengths, as well as bisphenol A and bisphenol S. In the absence of SCD in running buffer, all the phenols migrated at the same velocity as the electroosmotic flow (EOF), whereas the addition of SCD effectively led to the baseline separation of alkylphenols on the basis of the difference in the abilities to bind into the hydrophobic cavity of CD. The host-guest binding constants between analyte phenols and SCD were evaluated from Benesi-Hildebrand plots of the data obtained by two independent methods, CE and UV-visible measurements, demonstrating that the greater the hydrophobicity of the phenols, the larger the binding constants. The effects of organic solvents on the resolution for alkylphenols and bisphenols were also examined. This system using SCD was effective for the separation of 4-octylphenol and 4-nonylphenol isomers having longer alkyl chains.

  18. High charged red pigment nanoparticles for electrophoretic displays (United States)

    Hou, Xin-Yan; Bian, Shu-Guang; Chen, Jian-Feng; Le, Yuan


    Organic pigment permanent red F2R nanoparticles were prepared via surface modification to improve the surface charge and dispersion ability in organic medium. Their large surface chargeability is confirmed by ζ-potential value of -49.8 mV. The prepared particles exhibited average size of 105 nm and showed very narrow distribution with polydispersity index of 0.068. The sedimentation ratio of the prepared particles in tetrachloroethylene was less than 5% within 12 days. The electrophoretic inks consisting of the prepared red particles with white particles as contrast showed good electrophoretic display, its refresh time was 200 ms.

  19. Photolithographic process of microcapsule sheet for electrophoretic display

    Energy Technology Data Exchange (ETDEWEB)

    Park, Lee Soon; Choi, Hyung Suk; Kim, Woo-Sik; Lee, Dong-Ho; Min, Kyung-Eun; Seo, Kwan-Ho; Kyu Kang, Inn; Park, Soo-Young; Ho Hwang, Sung; Kwon, Younghwan


    A new method of fabricating electrophoretic display sheet was developed utilizing a photolithographic process. In this method, stripe-type barrier ribs with height of 50-80 {mu}m and gap between ribs of 100-150 {mu}m were patterned on the transparent electrode substrate by photolithographic process using a negative-type photoresist. Microspheres dispersed in UV curable monomer system were closely packed into the spaces between the barrier ribs. After laminating the upper ITO film, the resulting sheet was UV-irradiated to give an electrophoretic display panel with uniform packing of microspheres.

  20. Anionic metabolite profiling by capillary electrophoresis-mass spectrometry using a noncovalent polymeric coating. Orange juice and wine as case studies. (United States)

    Acunha, Tanize; Simó, Carolina; Ibáñez, Clara; Gallardo, Alberto; Cifuentes, Alejandro


    In several metabolomic studies, it has already been demonstrated that capillary electrophoresis hyphenated to mass spectrometry (CE-MS) can detect an important group of highly polar and ionized metabolites that are overseen by techniques such as NMR, LC-MS and GC-MS, providing complementary information. In this work, we present a strategy for anionic metabolite profiling by CE-MS using a cationic capillary coating. The polymer, abbreviated as PTH, is composed of a poly-(N,N,N',N'-tetraethyldiethylenetriamine, N-(2-hydroxypropyl) methacrylamide, TEDETAMA-co-HPMA (50:50) copolymer. A CE-MS method based on PTH-coating was optimized for the analysis of a group of 16 standard anionic metabolites. Separation was achieved within 12min, with high separation efficiency (up to 92,000 theoretical plates per meter), and good repeatability, namely, relative standard deviation values for migration times and peak areas were below 0.2 and 2.1%, respectively. The optimized method allowed the detection of 87 metabolites in orange juice and 142 metabolites in red wine, demonstrating the good possibilities of this strategy for metabolomic applications.

  1. Stereospecific capillary electrophoresis assays using pentapeptide substrates for the study of Aspergillus nidulans methionine sulfoxide reductase A and mutant enzymes. (United States)

    Zhu, Qingfu; El-Mergawy, Rabab G; Zhou, Yuzhen; Chen, Chunyang; Heinemann, Stefan H; Schönherr, Roland; Robaa, Dina; Sippl, Wolfgang; Scriba, Gerhard K E


    Stereospecific capillary electrophoresis-based methods for the analysis of methionine sulfoxide [Met(O)]-containing pentapeptides were developed in order to investigate the reduction of Met(O)-containing peptide substrates by recombinant Aspergillus nidulans methionine sulfoxide reductase A (MsrA) as well as enzymes carrying mutations in position Glu99 and Asp134. The separation of the diastereomers of the N-acetylated, C-terminally 2,4-dinitrophenyl (Dnp)-labeled pentapeptides ac-Lys-Phe-Met(O)-Lys-Lys-Dnp, ac-Lys-Asp-Met(O)-Asn-Lys-Dnp and ac-Lys-Asn-Met(O)-Asp-Lys-Dnp was achieved in 50 mM Tris-HCl buffers containing sulfated β-CD in fused-silica capillaries, while the diastereomer separation of ac-Lys-Asp-Met(O)-Asp-Lys-Dnp was achieved by sulfated β-CD-mediated MEKC. The methods were validated with regard to range, linearity, accuracy, limits of detection and quantitation as well as precision. Subsequently, the substrates were incubated with wild-type MsrA and three mutants in the presence of dithiothreitol as reductant. Wild-type MsrA displayed the highest activity towards all substrates compared to the mutants. Substitution of Glu99 by Gln resulted in the mutant with the lowest activity towards all substrates except for ac-Lys-Asn-Met(O)-Asp-Lys-Dnp, while replacement Asn for Asp134 lead to a higher activity towards ac-Lys-Asp-Met(O)-Asn-Lys-Dnp compared with the Glu99 mutant. The mutant with Glu instead of Asp134 was the most active among the mutant enzymes. Molecular modeling indicated that the conserved Glu99 residue is buried in the Met-S-(O) groove, which might contribute to the correct placing of substrates and, consequently, to the catalytic activity of MsrA, while Asp134 did not form hydrogen bonds with the substrates but only within the enzyme.

  2. Measurement of Capillary Radius and Contact Angle within Porous Media. (United States)

    Ravi, Saitej; Dharmarajan, Ramanathan; Moghaddam, Saeed


    The pore radius (i.e., capillary radius) and contact angle determine the capillary pressure generated in a porous medium. The most common method to determine these two parameters is through measurement of the capillary pressure generated by a reference liquid (i.e., a liquid with near-zero contact angle) and a test liquid. The rate of rise technique, commonly used to determine the capillary pressure, results in significant uncertainties. In this study, we utilize a recently developed technique for independently measuring the capillary pressure and permeability to determine the equivalent minimum capillary radii and contact angle of water within micropillar wick structures. In this method, the experimentally measured dryout threshold of a wick structure at different wicking lengths is fit to Darcy's law to extract the maximum capillary pressure generated by the test liquid. The equivalent minimum capillary radii of different wick geometries are determined by measuring the maximum capillary pressures generated using n-hexane as the working fluid. It is found that the equivalent minimum capillary radius is dependent on the diameter of pillars and the spacing between pillars. The equivalent capillary radii of micropillar wicks determined using the new method are found to be up to 7 times greater than the current geometry-based first-order estimates. The contact angle subtended by water at the walls of the micropillars is determined by measuring the capillary pressure generated by water within the arrays and the measured capillary radii for the different geometries. This mean contact angle of water is determined to be 54.7°.

  3. Determination of the Acid-Base Dissociation Constant of Acid-Degradable Hexamethylenetetramine by Capillary Zone Electrophoresis. (United States)

    Takayanagi, Toshio; Shimakami, Natsumi; Kurashina, Masashi; Mizuguchi, Hitoshi; Yabutani, Tomoki


    The acid-base equilibrium of hexamethylenetetramine (hexamine) was analyzed with its effective electrophoretic mobility by capillary zone electrophoresis. Although hexamine is degradable in a weakly acidic aqueous solution, and the degraded products of ammonia and formaldehyde can be formed, the effective electrophoretic mobility of hexamine was measured in the pH range between 2.8 and 6.9. An acid-base dissociation equilibrium of the protonated hexamine was analyzed based on the mobility change, and an acid dissociation constant of pKa = 4.93 ± 0.01 (mean ± standard error, ionic strength: 0.020 mol dm(-3)) was determined. The monoprotic acid-base equilibrium of hexamine was confirmed through comparisons of its electrophoretic mobility with the N-ethylquinolinium ion and with the monocationic N-ethyl derivative of hexamine, as well as a slope analysis of the dissociation equilibrium.

  4. Sample injection and electrophoretic separation on a simple laminated paper based analytical device. (United States)

    Xu, Chunxiu; Zhong, Minghua; Cai, Longfei; Zheng, Qingyu; Zhang, Xiaojun


    We described a strategy to perform multistep operations on a simple laminated paper-based separation device by using electrokinetic flow to manipulate the fluids. A laminated crossed-channel paper-based separation device was fabricated by cutting a filter paper sheet followed by lamination. Multiple function units including sample loading, sample injection, and electrophoretic separation were integrated on a single paper based analytical device for the first time, by applying potential at different reservoirs for sample, sample waste, buffer, and buffer waste. As a proof-of-concept demonstration, mixed sample solution containing carmine and sunset yellow were loaded in the sampling channel, and then injected into separation channel followed by electrophoretic separation, by adjusting the potentials applied at the four terminals of sampling and separation channel. The effects of buffer pH, buffer concentration, channel width, and separation time on resolution of electrophoretic separation were studied. This strategy may be used to perform multistep operations such as reagent dilution, sample injection, mixing, reaction, and separation on a single microfluidic paper based analytical device, which is very attractive for building micro total analysis systems on microfluidic paper based analytical devices.

  5. Electrophoretic deposition of iron catalyst on C-fiber textiles for the growth of carbon nanofibers. (United States)

    Lee, Sang-Won; Lee, Chang-Seop


    In this study, carbon nanofibers synthesis has been conducted by chemical vapor deposition on C-fiber textiles coated with an iron catalyst via electrophoretic deposition. C-fiber textiles were oxidized with nitric acid before the iron catalyst was plated by electrophoretic deposition. Due to oxidation, the hydroxyl group was created on the C-fiber textiles and was used as an active site for iron catalyst deposition. It was verified that the iron catalyst was deposited on the C-fiber textiles, while current, voltage, and deposition time varied and the concentration of electrolyte was kept constant in electrophoretic deposition. After being deposited, the iron particles were dried in oven for 24 hours and reduced by hydrogen gas in a furnace. Ethylene gas was introduced for the growth of carbon nanofibers and the growth temperature was then varied to find the optimal growth temperature of the carbon nanofibers. Thus, the characteristics of carbon nanofibers were analyzed by Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), N2-sorption (BET), X-Ray Diffraction (XRD), and X-ray Photoelectron Spectroscopy (XPS). It is verified that the iron particles were most evenly deposited at 0.1 A for 3 minutes. Carbon nanofibers grew to 150-200 nm most evenly at 600 degrees C via temperature variations in CVD.

  6. Determination of the Median Lethal Dose and Electrophoretic Pattern of Hottentotta saulcyi (Scorpiones, Buthidae Scorpion Venom

    Directory of Open Access Journals (Sweden)

    ErsenAydın Yağmur


    Full Text Available Background: In this study, we investigated the lethal potency, electrophoretic protein pattern and in vivo effects of Hottentotta saulcyi scorpion venom in mice.Methods: Scorpions were collected at night, by using a UV lamp from Mardin Province, Turkey. Venom was obtained from mature H. saulcyi scorpions by electrical stimulation of the telson. The lethality of the venom was determined by i.v. injections using Swiss mice. In vivo effects of the venom were assessed by using the intraperitoneal route (ip injections into mice (20±1g and monitored for 24 h. The protein profiles of the scorpion venom were analyzed by NuPAGE® Novex® 4–12 % gradient Bis-Tris gel followed by Coomassie blue staining.Results: The lethal assay of the venom was 0.73 mg/kg in mice. We determined the electrophoretic protein pattern of this scorpion venom to be 4, 6, 9, 31, 35, 40, 46 and 69 kDa by SDS-PAGE. Analysis of electrophoresis indicated that H. saulcyi scorpion intoxicated mice exhibited autonomic nervous system symptoms (tachypnea, restlessness, hyperexcitability, convulsions, salivation, lacrimation, weakness.Conclusions: Hottentotta saulcyi scorpion venom includes short-chain neurotoxins and long-chain neurotoxins according to the electrophoretic protein patterns. The stings of H. saulcyi scorpion must be considered of risk for humans in the southeastern region, Turkey.


    Institute of Scientific and Technical Information of China (English)


    Separation and determination of metal ions based on the formation of chelate anions with 1-Nitroso-2,7-dihydrexynaphthalene-3,6-di sulfonic acid(1N2,7O3,6S) was studied by using HPCE of the nine metal ions exami ned, the ions that can be detected sensitively with 1-Nitroso-2,7-dihydrexyna phtha lene-3,6-disulfonic acid were Fe2+,Co2+,Cu2+,Ni2+,Zn 2+ and Pd2+. The cobalt chelate could exist in two oxidation stat es of cobalt. When TBA+ were added in electrophoretic solutions, the drastic c ha nges in electrophoretic mobilities of chelate were observed, which was due to th e ion association between chelates anions and TBA+. The ion association consta nts of chelate anions with TBA+ were determined by using the change in electro p horetic mobilities of chelates, metal ions tested were separated within 10 min u sing 30cm silica capillary(50 m i.d).

  8. Label-free solution-based kinetic study of aptamer-small molecule interactions by kinetic capillary electrophoresis with UV detection revealing how kinetics control equilibrium. (United States)

    Bao, Jiayin; Krylova, Svetlana M; Reinstein, Oren; Johnson, Philip E; Krylov, Sergey N


    Here we demonstrate a label-free solution-based approach for studying the kinetics of biopolymer-small molecule interactions. The approach utilizes kinetic capillary electrophoresis (KCE) separation and UV light absorption detection of the unlabeled small molecule. In this proof-of-concept work, we applied KCE-UV to study kinetics of interaction between a small molecule and a DNA aptamer. From the kinetic analysis of a series of aptamers, we found that dissociation rather than binding controls the stability of the complex. Because of its label-free features and generic nature, KCE-UV promises to become a practical tool for challenging kinetic studies of biopolymer-small molecule interactions.

  9. On-line capillary isotachophoresis-capillary zone electrophoresis analysis of bromate in drinking waters in an automated analyzer with coupled columns and photometric detection. (United States)

    Marák, Jozef; Staňová, Andrea; Vaváková, Veronika; Hrenáková, Martina; Kaniansky, Dušan


    A new, sensitive, and robust analytical method based on capillary zone electrophoresis with on-line capillary isotachophoresis sample pretreatment (ITP-CZE) using a column-coupling (CC) arrangement of automated capillary electrophoretic analyzer was developed for determination of bromate in different type of drinking water samples. Both columns were provided with contact-less conductivity detectors and in CZE step UV detection at 200 nm wavelength was used. Electroosmotic flow of the buffer solutions was suppressed with the addition of 0.1% or 0.05% (m/v) methylhydroxyethylcellulose into the leading and terminating electrolyte, respectively. Hydrodynamic and electroosmotic flows of the buffer solutions were successfully suppressed and therefore, only the electrophoretic transport of ions was significant. Limit of detection for bromate approaching 0.6 μg/L was achieved. Good repeatabilities of migration time (RSD less than 0.3%) and peak area (RSD less than 4.0%) at concentration level 1 μg/L were obtained. Robustness of proposed ITP-CZE method and validation parameters were evaluated. Developed automated ITP-CZE method was applied to the determination of bromate in drinking water samples with different content of inorganic macroconstituents without the need of further sample preparation.

  10. An axial approach to detection in capillary electrophoresis

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, J.A.


    Our approach involves on-axis illumination of the compounds inside the capillary detection region and is applied to absorbance and fluorescence detection. Absorbance measurements were made by focussing an incident laser beam into one capillary end; by using signals collected over the entire length of analyte band, this enhances the analytical path length of conventional absorbance detection 60x. This instrument offers a 15x improvement in detection limits. Three fluorescence detection experiments are discussed, all of which involve insertion of an optical fiber into capillary. The first uses a high refractive index liquid phase to obtain total internal reflectance along capillary axis, this reducing light scatter. The second uses a charge-coupled device camera for simultaneous imaging of a capillary array (this may be useful in genome sequencing, etc.). The third is a study of fluid motion inside the capillary under pressure-driven and electroosmotic flow. The thesis is divided into four parts. Figs, tabs.

  11. Capillary permeability in adipose tissue

    DEFF Research Database (Denmark)

    Paaske, W P; Nielsen, S L


    of about 7 ml/100 g-min. This corresponds to a capillary diffusion capacity of 2.0 ml/100 g-min which is half the value reported for vasodilated skeletal muscle having approximately twice as great capillary surface area. Thus, adipose tissue has about the same capillary permeability during slight metabolic...

  12. Electrophoretic separation of kidney and pituitary cells on STS-8 (United States)

    Morrison, D. R.; Nachtwey, D. S.; Barlow, G. H.; Cleveland, C.; Lanham, J. W.; Farrington, M. A.; Hatfield, J. M.; Hymer, W. C.; Todd, P.; Wilfinger, W.; Grindeland, R.; Lewis, M. L.

    A Continuous Flow Electrophoresis System (CFES) was used on Space Shuttle flight STS-8 to separate specific secretory cells from suspensions of cultured primary human embryonic kidney cells and rat pituitary cells. The objectives were to isolate the subfractions of kidney cells that produce the largest amounts of urokinase (plasminogen activator), and to isolate the subfractions of rat pituitary cells that secrete growth hormone, prolactin, and other hormones. Kidney cells were separated into more than 32 fractions in each of two electrophoretic runs. Electrophoretic mobility distributions in flight experiments were spread more than the ground controls. Multiple assay methods confirmed that all cultured kidney cell fractions produced some urokinase, and five to six fractions produced significantly more urokinase than the other fractions. Several fractions also produced tissue plasminogen activator. The pituitary cells were separated into 48 fractions in each of the two electrophoretic runs, and the amounts of growth hormone (GH) and prolactin (PRL) released into the medium for each cell fraction were determined. Cell fractions were grouped into eight mobility classes and immunocytochemically assayed for the presence of GH, PRL, ACTH, LH, TSH, and FSH. The patterns of hormone distribution indicate that the specialized cells producing GH and PRL are isolatable due to the differences in electrophoretic mobilities.

  13. Controlled method of reducing electrophoretic mobility of various substances (United States)

    Vanalstine, James M. (Inventor)


    A method of reducing electrophoretic mobility of macromolecules, particles, cells, and the like is provided. The method comprises interacting the particles or cells with a polymer-linked affinity compound composed of: a hydrophilic neutral polymer such as polyethylene glycol, and an affinity component consisting of a hydrophobic compound such as a fatty acid ester, an immunocompound such as an antibody or active fragment thereof or simular macromolecule, or other ligands. The reduction of electrophoretic mobility achieved is directly proportional to the concentration of the polymer-linked affinity compound employed, and the mobility reduction obtainable is up to 100 percent for particular particles and cells. The present invention is advantageous in that analytical electrophoretic separation can not be achieved for macromolecules, particles, and cells whose native surface charge structure had prevented them from being separated by normal electrophoretic means. Depending on the affinity component utilized, separation can be achieved on the basis of specific/irreversible, specific/reversible, semi-specific/reversible, relatively nonspecific/reversible, or relatively nonspecific/irreversible ligand-substance interactions. The present method is also advantageous in that it can be used in a variety of standard laboratory electrophoresis equipment.

  14. Application of liquid pre-column capillary electrophoresis technique to the study of interaction between drug enantiomers and human serum albumin

    Institute of Scientific and Technical Information of China (English)

    丁永生; 朱晓蜂; 林炳承


    Based on the chiral separation of several basie drugs, dimetindene, tetryzoline, theodrenaline and verapamil, the liquid pre-colunm capillary electrophoresis (LPC-CE) technique was established. It was used to determine free concentrations of drug enantiomers in mixed solutions with human serum albumin (HSA). To prevent HSA entering the CE chiral separation zone, the mobility differences between HSA and drugs under a specific pH condition were employed in the LPC. Thus, the detection confusion caused by protein was totally avoided. Further study of binding constants determination and protein binding competitions was carried out. The study proves that the LPC technique could be used for complex media, particularly the matrix of protein coexisting with a variety of drugs.

  15. Advances in Capillary Chromatography%毛细管色谱的进展

    Institute of Scientific and Technical Information of China (English)


    Capillary columns are used in both capillary liquid chromatography and capillary electrochromatography. The design for capillary liquid chromatography is discussed in comparison with capillary gas chromatography. The difference of diffusion coefficient in gas and liquid phase is a key role. The study for obtaining a high performance capillary liquid chromatography is discussed. Capillary electrochromatography is recently interesting for its instinct ability to realize a high performance chromatography. Capillary electrochromatography with and without pressurized flow is reviewed briefly. Instrumentation for capillary electrochromatography with pressurized flow is discussed. The port of splitting, and gradient elution of both solution and potential are described. The new findings of both the variation of column resistance and capacity factor according to the value of applied electric voltage are also discussed.

  16. Study on the potential application of salivary inorganic anions in clinical diagnosis by capillary electrophoresis coupled with contactless conductivity detection. (United States)

    Guo, Lin; Wang, Yu; Zheng, Yiliang; Huang, Zhipeng; Cheng, Yiyuan; Ye, Jiannong; Chu, Qingcui; Huang, Dongping


    A capillary electrophoresis approach with capacitively coupled contactless conductivity detection method has been developed for the determination of inorganic metabolites (thiocyanate, nitrite and nitrate) in human saliva. Field amplified sample injection, as a simple sample stacking technique, was used in conjunction for online preconcentration of above inorganic anions. A selective separation for the target anions from other coexisting constituents present in saliva could be obtained within 14min in a 10mmol/L His-90mmol/L HAc buffer (pH 3.70) at the separation voltage of -18kV. The limits of detection and limits of quantification of the three analytes were within the range of 3.1-4.9ng/mL (S/N=3) and 10-16ng/mL (S/N=10), respectively. The average recovery data were in the range of 81-108% at three different concentrations. This method provides a simple, rapid and direct approach for metabolite analyses of nitric oxide and cyanide based on noninvasive saliva sample, which presents a potential fast screening tool for clinical test.

  17. Using affinity capillary electrophoresis and computational models for binding studies of heparinoids with p-selectin and other proteins. (United States)

    Mozafari, Mona; Balasupramaniam, Shantheya; Preu, Lutz; El Deeb, Sami; Reiter, Christian G; Wätzig, Hermann


    A fast and precise affinity capillary electrophoresis (ACE) method has been developed and applied for the investigation of the binding interactions between P-selectin and heparinoids as potential P-selectin inhibitors in the presence and absence of calcium ions. Furthermore, model proteins and vitronectin were used to appraise the binding behavior of P-selectin. The normalized mobility ratios (∆R/Rf ), which provided information about the binding strength and the overall charge of the protein-ligand complex, were used to evaluate the binding affinities. It was found that P-selectin interacts more strongly with heparinoids in the presence of calcium ions. P-selectin was affected by heparinoids at the concentration of 3 mg/L. In addition, the results of the ACE experiments showed that among other investigated proteins, albumins and vitronectin exhibited strong interactions with heparinoids. Especially with P-selectin and vitronectin, the interaction may additionally induce conformational changes. Subsequently, computational models were applied to interpret the ACE experiments. Docking experiments explained that the binding of heparinoids on P-selectin is promoted by calcium ions. These docking models proved to be particularly well suited to investigate the interaction of charged compounds, and are therefore complementary to ACE experiments. This article is protected by copyright. All rights reserved.

  18. [Determination of gambogic acid in Gamboge by non-aqueous capillary electrophoresis]. (United States)

    Ou, Wanlu; Li, Yujuan; Shi, Dongdong; Qu, Feng


    Gambogic acid (GA), a kind of caged xanthones, has low solubility in water. A non-aqueous capillary electrophoresis (NACE) was established for the determination of GA in Gamboge based on the optimized conditions. The effect of 20% - 60% methanol or acetonitrile spiked in running solution was investigated. The effects of compositions, concentration, pH, additives like β-cyclodextrin in running buffer were thoroughly studied. Applied voltage and applied temperature were also observed. Optimal electrophoretic conditions were as follows: 20 mmol/L sodium borohydride solution (pH 9. 86) containing 40% (v/v) acetonitrile, 10 mmol/L β-cyclodextrin as running buffer, applied voltage of 10 kV, capillary temperature of 30 °C and detection wavelength of 280 nm. The calibration curve had good linearity in the range of 2-2 000 mg/L with the correlation coefficient of 0. 999 6. The limit of quantification (S/N= 3) of the method was 2 mg/L. The quantifications of GA in Gamboge from different producing places including Vietnam, Thailand, Burma, India were 1. 67-472.40 mg/g with the RSD (n= 3) of 1.12% -2.60%. The content of Gamboge from Vietnam is obviously low while the others are high. The recoveries of GA spiked in real samples ranged from 95. 2% to 105. 6%. The method of NACE is simple, efficient and of good reproducibility, can be served as a novel reference to identify and control the quality of Gamboge.

  19. Fuzzy Control of the coating quality parameters Electrophoretic studies the economics of quality%基于模糊质量参数控制的涂装电泳质量经济性研究

    Institute of Scientific and Technical Information of China (English)

    杨培佑; 张敏; 刘坚


    In order to reasonable and effective control of automotive painting electrophoretic coating process on the impact of product quality, important process parameters on the electrophoresis process solids, proposed the concept of fuzzy quality characteristics. Monitoring model based on fuzzy quality characteristics, the quality characteristics of the fuzziness and randomness combined for electrophoresis bath solids content analysis, which gives quality characteristics of solids fuzzy conditional probability. And the use of Bayesian decision making and quality characteristics of this cost function for further analysis, the electrophoresis bath Solids quantitative fuzzy quality control and monitoring model. Monitoring the quality characteristics of fuzzy model economy in automotive coating applications on electrophoresis. Specific practical application show that the method in the field of automotive painting feasibility and applicability.%为合理并有效地控制汽车涂装电泳工艺对涂装产品质量的影响,对电泳过程重要工艺参数固体份,提出了模糊质量特性的概念。基于模糊质量特性监测模型,将质量特性的模糊性与随机性相结合对电泳槽液固体份含量进行分析,从而给出固体份质量特性的模糊条件概率。并运用贝叶斯决策与成本函数对这一质量特性进一步分析,提出电泳槽液固体份含量的量化模糊质量控制与监测模型。研究模糊质量特性监测模型在汽车涂装电泳经济性上的应用。具体的实际应用证明了该方法在汽车涂装领域的可行性与适用性。

  20. DNA Sequencing Using capillary Electrophoresis

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Barry Karger


    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

  1. Preparation and application of microcapsule-encapsulated color electrophortic fluid in Isopar M system for electrophoretic display (United States)

    Sun, Cui; Feng, Ya-Qing; Zhang, Bao; Li, Xiang-Gao; Shao, Ji-Zhou; Han, Jing-Jing; Chen, Xu


    The use of Isopar M as a liquid suspending fluid for electrophoretic display was studied. The dispersion stability and chargeability of pigments suspended in Isopar M were investigated. Polyisobutylene monosuccinimide (T-151) as the charge control additive in Isopar M electrophoretic fluid can provide a good electrophoretic mobility to the particles. The wall materials of a series of blue-white, red-white and yellow-white dual-particle microcapsules were prepared by in situ polymerization of urea and formaldehyde. The mass ratio of wall/core material was a key factor in influencing the yield of microcapsules. The concentration of resorcinol has an impact on the surface morphology and mechanical strength of microcapsule wall. Microcapsules' surface morphologies were characterized by optical microscopy and scanning electron microscopy. The performance of the microcapsules with different binder materials and adhesive layers were investigated. Contrast ratio of microcapsules display device were tested every 10 days for a period of 90 days. The compatibility of Isopar M with both the electrophoretic particles and bounding capsule was studied.

  2. Affinity Capillary Electrophoresis:Study of the Binding of HIV-1 gp41 with a Membrane Protein (P45) on the Human B Cell Line,Raji

    Institute of Scientific and Technical Information of China (English)


    Affinity capillary electrophoresis has been used to study the interaction between a membrane protein (P45) isolated from the Human B cell line, Raji, and rsgp41. P45, rsgp41 and the complexes were well resolved. The entire separation was achieved in less than 3min. Formations of two kinds of stable P45-rsgp41 complexes were confirmed based on migration time comparison; the binding equilibrium was achieved as soon as two proteins were mixed. The results indicate that the interaction between P45 and rsgp41 is strong with a fast association rate and a slow dissociation rate, and there are at least two kinds of binding sites with different binding constants between P45 and rsgp41.

  3. Numerical study of two-phase flows in porous media : extraction of a capillary pressure saturation curve free from boundary effects (United States)

    Fiorentino, Eve-Agnès; Moura, Marcel; Jørgen Måløy, Knut; Toussaint, Renaud; Schäfer, Gerhard


    The capillary pressure saturation relationship is a key element in the resolution of hydrological problems that involve the closure partial-flow Darcy relations. This relationship is derived empirically, and the two typical curve fitting equations that are used to describe it are the Brooks-Corey and Van Genüchten models. The question we tackle is the influence of the boundary conditions of the experimental set-up on the measurement of this retention curve, resulting in a non physical pressure-saturation curve in porous media, due the "end effects" phenomenon. In this study we analyze the drainage of a two-phase flow from a quasi 2D random porous medium, and compare it to simulations arising from an invasion percolation algorithm. The medium is initially saturated with a viscous fluid, and as the pressure difference is gradually increased, air penetrates from an open inlet, thus displacing the fluid which leaves the system from the outlet in the opposing side. In the initial stage, the liquid-air interface evolves from a planar front to the fractal structure characteristic of slow drainage processes, giving the initial downward curvature. In the final stage, air spreads all along the filter, and must reach narrower pores, calling for an increase of the pressure difference, reflected by the final upward curvature. Measuring the pressure-saturation (P-S) law in subwindows located at the inlet, outlet and middle of the network, we emphasize that these boundary effects are the fact of a fraction of pores that is likely to be negligible for high scale systems. We analyze the value of the air saturation at the end of the experiment for a series of simulations with different sample geometries : we observe that this saturation converges to a plateau when the distance between the inlet ant outlet increases, and that the value of this plateau is determined by the distance between the lateral walls. We finally show that the pressure difference between the two phases

  4. Final report of “A Detailed Study of the Physical Mechanisms Controlling CO2-Brine Capillary Trapping in the Subsurface” (University of Arizona, DE-SC0006696)

    Energy Technology Data Exchange (ETDEWEB)

    Schaap, Marcel G. [Univ. of Arizona, Tucson, AZ (United States)


    Carbon capture and storage (CCS) of carbon dioxide emissions generated by production or combustion of fossil fuels is a technologically viable means to reduce the build-up of CO2 in the atmosphere and oceans. Using advantages of scale and location, CCS is particularly suitable for large point sources near ubiquitous deep saline aquifers, depleted gas reservoirs, or at production reservoirs for enhanced oil recovery (EOR). In the BES-funded research project, Oregon State University (OSU) carried out capillary trapping experiments with proxy fluids that mimic the properties of the scCO2/brine system under ambient temperatures and pressures, and successfully developed a unique and novel x-ray compatible, high-pressure, elevated temperature setup to study the scCO2/brine system under challenging reservoir conditions. Both methodologies were applied to a variety of porous media, including synthetic (glass bead) and geologic (Bentheimer sandstone) materials. The University of Arizona (UA) developed pore-scale lattice Boltzmann (LB) models which are able to handle the experimental conditions for proxy fluids, as well as the scCO2/brine system, that are capable of simulating permeability in volumes of tens of millions of fluid elements. We reached the following summary findings (main institute indicated): 1. (OSU/UA) To understand capillary trapping in a multiphase fluid-porous medium system, the system must be analyzed from a pore-scale force balance perspective; trapping can be enhanced by manipulating wetting and nonwetting phase fluid properties. 2. (OSU) Pore-scale fluid connectivity and topology has a clear and direct effect on nonwetting phase capillary trapping efficiency. 3. (OSU) Rock type and flow regime also have a pronounced effects on capillary trapping. 4. (OSU/UA) There is a predictable relationship between NWP connectivity and NWP saturation, which allows for development of injection strategies that optimize trapping. The commonly used Land model (Land

  5. Preparation approaches of the coated capillaries with liposomes in capillary electrophoresis. (United States)

    Mei, Jie; Tian, Yan-Ping; He, Wen; Xiao, Yu-Xiu; Wei, Juan; Feng, Yu-Qi


    The use of liposomes as coating materials in capillary electrophoresis has recently emerged as an important and popular research area. There are three preparation methods that are commonly used for coating capillaries with liposomes, namely physical adsorption, avidin-biotin binding and covalent coupling. Herein, the three different coating methods were compared, and the liposome-coated capillaries prepared by these methods were evaluated by studying systematically their EOF characterization and performance (repeatability, reproducibility and lifetime). The amount of immobilized phospholipids and the interactions between liposome or phospholipid membrane and neutral compounds for the liposome-coated capillaries prepared by these methods were also investigated in detail. Finally, the merits and disadvantages for each coating method were reviewed.

  6. Ionic liquids in chromatographic and electrophoretic techniques: toward additional improvements in the separation of natural compounds (United States)

    Freire, Carmen S. R.; Coutinho, João A. P.; Silvestre, Armando J. D.; Freire, Mara G.


    Due to their unique properties, in recent years, ionic liquids (ILs) have been largely investigated in the field of analytical chemistry. Particularly during the last sixteen years, they have been successfully applied in the chromatographic and electrophoretic analysis of value-added compounds extracted from biomass. Considering the growing interest in the use of ILs in this field, this critical review provides a comprehensive overview on the improvements achieved using ILs as constituents of mobile or stationary phases in analytical techniques, namely in capillary electrophoresis and its different modes, in high performance liquid chromatography, and in gas chromatography, for the separation and analysis of natural compounds. The impact of the IL chemical structure and the influence of secondary parameters, such as the IL concentration, temperature, pH, voltage and analysis time (when applied), are also critically addressed regarding the achieved separation improvements. Major conclusions on the role of ILs in the separation mechanisms and the performance of these techniques in terms of efficiency, resolution and selectivity are provided. Based on a critical analysis of all published results, some target-oriented ILs are suggested. Finally, current drawbacks and future challenges in the field are highlighted. In particular, the design and use of more benign and effective ILs as well as the development of integrated (and thus more sustainable) extraction–separation processes using IL aqueous solutions are suggested within a green chemistry perspective. PMID:27667965

  7. Ionic liquids in chromatographic and electrophoretic techniques: toward additional improvements in the separation of natural compounds. (United States)

    Soares, Belinda; Passos, Helena; Freire, Carmen S R; Coutinho, João A P; Silvestre, Armando J D; Freire, Mara G


    Due to their unique properties, in recent years, ionic liquids (ILs) have been largely investigated in the field of analytical chemistry. Particularly during the last sixteen years, they have been successfully applied in the chromatographic and electrophoretic analysis of value-added compounds extracted from biomass. Considering the growing interest in the use of ILs in this field, this critical review provides a comprehensive overview on the improvements achieved using ILs as constituents of mobile or stationary phases in analytical techniques, namely in capillary electrophoresis and its different modes, in high performance liquid chromatography, and in gas chromatography, for the separation and analysis of natural compounds. The impact of the IL chemical structure and the influence of secondary parameters, such as the IL concentration, temperature, pH, voltage and analysis time (when applied), are also critically addressed regarding the achieved separation improvements. Major conclusions on the role of ILs in the separation mechanisms and the performance of these techniques in terms of efficiency, resolution and selectivity are provided. Based on a critical analysis of all published results, some target-oriented ILs are suggested. Finally, current drawbacks and future challenges in the field are highlighted. In particular, the design and use of more benign and effective ILs as well as the development of integrated (and thus more sustainable) extraction-separation processes using IL aqueous solutions are suggested within a green chemistry perspective.

  8. Carboxylated ficolls: preparation, characterization, and electrophoretic behavior of model charged nanospheres. (United States)

    Guo, Xuhong; Kirton, Gavin F; Dubin, Paul L


    Carboxylated ficolls were prepared as model spherical colloids of variable charge and size, with radii ranging from 3.0 to 19.3 nm. Capillary electrophoresis (CE), electrophoretic light scattering (ELS), and potentiometric titration were used to determine mobilities as a function of pH, degree of ionization alpha, and surface potential psi(0). Measured mobilities typically display a plateau at high pH, corresponding to high alpha and psi(0), confirming the general nature of this effect for charged spheres, seen also for charged dendrimers and charged latex particles. This result is examined in the context of a discontinuity in mobility predicted by the Wiersema, O'Brien, and White (WOW) theory and a more recent primitive model electrophoresis (PME) theory, in which bound counterions are considered either as point charges or as hard spheres. While no mobility maximum can be determined as expected by these two theories, our data seem more to support Belloni's theoretical expectations on charged polymers and spheres. Here we explain the mobility plateaus in terms of counterions accumulated close to the surface (surface potential-determining ions) or within the shear plane (mobility-determining ions).

  9. Studies of the influence of nonequilibrium plasma thermal exposure on the characteristics of the capillary-porous polymer material (United States)

    Makhotkina, L. Yu; Khristoliubova, V. I.


    Capillary-porous materials, which include natural macromolecular tanning material, are exposed to a number of factors during the treatment by a nonequilibrium plasma. Plasma particles exchange the charge and energy with the atoms of the material during the interaction of the plasma with the surface. The results of treatment are desorption of atoms and molecules from the body surface, sputtering and evaporation of material’s particles, changes of the structure and phase state. In real terms during the modification of solids by nonequilibrium low-temperature plasma thermal effect influences the process. The energy supplied from the discharge during the process with low pressure, which is converted into heat, is significantly less than during the atmospheric pressure, but the thermal stability of high-molecular compounds used in the manufacture of materials and products of the tanning industry, is very limited and depends on the duration of the effect of temperature. Even short heating of hydrophilic polymers (proteins) (100-180 °C) causes a change in their properties. It decreases the collagen ability to absorb water vapor, to swell in water, acids, alkalis, and thus decreases their durability. Prolonged heating leads to a deterioration of the physical and mechanical properties. Higher heating temperatures it leads to the polymer degradation. The natural leather temperature during plasma exposure does not rise to a temperature of collagen degradation and does not result in changes of physical phase of the dermis. However, the thermal plasma exposure must be considered, since the high temperatures influence on physical and mechanical properties.

  10. Evidence of different stoichiometries for the limiting carbonate complexes across the lanthanide(III) series: A capillary electrophoresis-mass spectrometry study

    Energy Technology Data Exchange (ETDEWEB)

    Philippini, V.; Vercouter, T.; Vitorge, P. [CEA, Dept Physicochem, Lab Speciat Radionucleides et Mol, F-91191 Gif Sur Yvette, (France); Aupiais, J.; Topin, S.; Ambard, C. [CEA, Serv Radioanalyse Chim et Environm, Bruyeres Le Chatel, (France); Chausse, A.; Vitorge, P. [Lab Analyse et Modelisat Biol et Environm, Evry, (France)


    The electrophoretic mobilities ({mu}{sub ep,Ln}) of twelve lanthanides (not Ce, Pr and Yb) were measured by CE-ICP-MS in 0.15 and 0.5 mol L{sup -1} Alk{sub 2}CO{sub 3} aqueous solutions for Alk{sup +} = Li{sup +}, Na{sup +}, K{sup +} and Cs{sup +}. In 0.5 mol L{sup -1} solutions, two different {mu}{sub ep,Ln} values were found for the light (La to Nd) and the heavy (Dy to Tm) lanthanides, which suggests two different stoichiometries for the carbonate limiting complexes. These results are consistent with a solubility study that attests the Ln(CO{sub 3}){sub 3}{sup 3-} and Ln(CO{sub 3}){sub 4}{sup 5-} stoichiometries for the heavy (small) and the light (big) lanthanides, respectively. The Alk{sup +} counter-ions influence the {mu}{sub ep,Ln}{sup Alk2CO3} values, but not the overall shape of the {mu}{sub ep,Ln}{sup Alk2CO3} plots as a function of the lanthanide atomic numbers: the counter-ions do not modify the stoichiometries of the inner sphere complexes. The influence of the Alk{sup +} counter-ions decreases in the Li{sup +} {>=} Na{sup +} {>=}{>=} K{sup +} {>=} Cs{sup +} series. The K{sub 3,Ln} stepwise formation constants of the Ln(CO{sub 3}){sub 3}{sup 3-} complexes slightly increase with the atomic numbers of the lanthanides while K{sub 4,Ln}, the stepwise formation constants of Ln(CO{sub 3}){sub 4}{sup 5-} complexes, slightly decrease from La to Th, and is no longer measurable for heavier lanthanides. (authors)

  11. Capillary electrophoresis to determine entrapment efficiency of a nanostructured lipid carrier loaded with piroxicam

    Institute of Scientific and Technical Information of China (English)

    Jessica Otarola; Adriana Guillermina Lista; Beatriz Fernández Band; Mariano Garrido


    A simple and fast capillary electrophoresis method has been developed to determine the amount of piroxicam loaded in a drug delivery system based on nanostructured lipid carriers (NLCs). The entrapment efficiency of the nanostructured lipid carrier was estimated by measuring the concentration of drug not entrapped in a suspension of NLC. The influence of different parameters on migration times, peak symmetry, efficiency and resolution was studied; these parameters included the pH of the electrophoretic buffer solution and the applied voltage. The piroxicam peak was obtained with a satisfactory resolution. The separation was carried out using a running buffer composed of 50 mM ammonium acetate and 13.75 mM ammonia at pH 9. The optimal voltage was 20 kV and the cartridge temperature was 20 1C. The corresponding calibration curve was linear over the range of 2.7–5.4 mg/mL of NLC suspension. The reproducibility of migration time and peak area were investigated, and the obtained RSD% values (n ¼ 5) were 0.99 and 2.13, respectively.

  12. Capillary electrophoresis to determine entrapment efficiency of a nanostructured lipid carrier loaded with piroxicam

    Directory of Open Access Journals (Sweden)

    Jessica Otarola


    Full Text Available A simple and fast capillary electrophoresis method has been developed to determine the amount of piroxicam loaded in a drug delivery system based on nanostructured lipid carriers (NLCs. The entrapment efficiency of the nanostructured lipid carrier was estimated by measuring the concentration of drug not entrapped in a suspension of NLC. The influence of different parameters on migration times, peak symmetry, efficiency and resolution was studied; these parameters included the pH of the electrophoretic buffer solution and the applied voltage. The piroxicam peak was obtained with a satisfactory resolution. The separation was carried out using a running buffer composed of 50 mM ammonium acetate and 13.75 mM ammonia at pH 9. The optimal voltage was 20 kV and the cartridge temperature was 20 °C. The corresponding calibration curve was linear over the range of 2.7–5.4 µg/mL of NLC suspension. The reproducibility of migration time and peak area were investigated, and the obtained RSD% values (n=5 were 0.99 and 2.13, respectively.

  13. Integrating Internal Standards into Disposable Capillary Electrophoresis Devices To Improve Quantification (United States)


    To improve point-of-care quantification using microchip capillary electrophoresis (MCE), the chip-to-chip variabilities inherent in disposable, single-use devices must be addressed. This work proposes to integrate an internal standard (ISTD) into the microchip by adding it to the background electrolyte (BGE) instead of the sample—thus eliminating the need for additional sample manipulation, microchip redesigns, and/or system expansions required for traditional ISTD usage. Cs and Li ions were added as integrated ISTDs to the BGE, and their effects on the reproducibility of Na quantification were explored. Results were then compared to the conclusions of our previous publication which used Cs and Li as traditional ISTDs. The in-house fabricated microchips, electrophoretic protocols, and solution matrixes were kept constant, allowing the proposed method to be reliably compared to the traditional method. Using the integrated ISTDs, both Cs and Li improved the Na peak area reproducibility approximately 2-fold, to final RSD values of 2.2–4.7% (n = 900). In contrast (to previous work), Cs as a traditional ISTD resulted in final RSDs of 2.5–8.8%, while the traditional Li ISTD performed poorly with RSDs of 6.3–14.2%. These findings suggest integrated ISTDs are a viable method to improve the precision of disposable MCE devices—giving matched or superior results to the traditional method in this study while neither increasing system cost nor complexity. PMID:28192985

  14. Reliable electrophoretic mobilities free from Joule heating effects using CE. (United States)

    Evenhuis, Christopher J; Hruska, Vlastimil; Guijt, Rosanne M; Macka, Miroslav; Gas, Bohuslav; Marriott, Philip J; Haddad, Paul R


    Ionic electrophoretic mobilities determined by means of CE experiments are sometimes different when compared to generally accepted values based on limiting ionic conductance measurements. While the effect of ionic strength on electrophoretic mobility has been long understood, the increase in the mobility that results from Joule heating (the resistive heating that occurs when a current passes through an electrolyte) has been largely overlooked. In this work, a simple method for obtaining reliable and reproducible values of electrophoretic mobility is described. The electrophoretic mobility is measured over a range of driving powers and the extrapolation to zero power dissipation is employed to eliminate the effect of Joule heating. These extrapolated values of electrophoretic mobility can then be used to calculate limiting ionic mobilities by making a correction for ionic strength; this somewhat complicated calculation is conveniently performed by using the freeware program PeakMaster 5. These straightforward procedures improve the agreement between experimentally determined and literature values of limiting ionic mobility by at least one order of magnitude. Using Tris-chromate BGE with a value of conductivity 0.34 S/m and ionic strength 59 mM at a modest dissipated power per unit length of 2.0 W/m, values of mobility for inorganic anions were increased by an average of 12.6% relative to their values free from the effects of Joule heating. These increases were accompanied by a reduction in mobilities due to the ionic strength effect, which was 11% for univalent and 28% for divalent inorganic ions compared to their limiting ionic mobilities. Additionally, it was possible to determine the limiting ionic mobility for a number of aromatic anions by using PeakMaster 5 to perform an ionic strength correction. A major significance of this work is in being able to use CE to obtain reliable and accurate values of electrophoretic mobilities with all its benefits, including

  15. Capillary condensation in porous alumina observed by positronium lifetime spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, Eugeniu [National Institute for Nuclear Physics and Engineering-Horia Hulubei, Atomistilor Street 407, CP MG 06, Magurele, Bucharest (Romania); Center for Advanced Studies in Physics of the Roumanian Academy, Casa Academiei Romane, Calea 13 Septembrie No. 13, Bucharest (Romania); Vata, Ion [National Institute for Nuclear Physics and Engineering-Horia Hulubei, Atomistilor Street 407, CP MG 06, Magurele, Bucharest (Romania)], E-mail:; Toderian, Stefan; Dudu, Dorin; Rusen, Ion; Stefan, Nitisor [National Institute for Nuclear Physics and Engineering-Horia Hulubei, Atomistilor Street 407, CP MG 06, Magurele, Bucharest (Romania)


    The PALS method based on time distribution measurements has been used to study capillary condensation of different gases adsorbed in microporous alumina powder. The isotherms exhibit features which are associated with a shifted gas-liquid transition. The sorption and desorption processes are irreversible presenting a hysteresis effect. Suggestions on some new aspects of the capillary condensation dynamics are made.

  16. Quality criterion to optimize separations in capillary electrophoresis: Application to the analysis of harmala alkaloids. (United States)

    Tascon, Marcos; Benavente, Fernando; Castells, Cecilia B; Gagliardi, Leonardo G


    In capillary electrophoresis (CE), resolution (Rs) and selectivity (α) are criteria often used in practice to optimize separations. Nevertheless, when these and other proposed parameters are considered as an elementary criterion for optimization by mathematical maximization, certain issues and inconsistencies appear. In the present work we analyzed the pros and cons of using these parameters as elementary criteria for mathematical optimization of capillary electrophoretic separations. We characterized the requirements of an ideal criterion to qualify separations within the framework of mathematical optimizations and, accordingly, propose: -1- a new elementary criterion (t') and -2- a method to extend this elementary criterion to compose a global function that simultaneously qualifies many different aspects, also called multicriteria optimization function (MCOF). In order to demonstrate this new concept, we employed a group of six alkaloids with closely related structures (harmine, harmaline, harmol, harmalol, harmane and norharmane). On the basis of this system, we present a critical comparison between the new optimization criterion t' and the former elementary criteria. Finally, aimed at validating the proposed methods, we composed an MCOF in which the capillary-electrophoretic separation of the six model compounds is mathematically optimized as a function of pH as the unique variable. Experimental results subsequently confirmed the accuracy of the model.

  17. Final report of “A Detailed Study of the Physical Mechanisms Controlling CO2-Brine Capillary Trapping in the Subsurface” (University of Arizona, DE-SC0006696)

    Energy Technology Data Exchange (ETDEWEB)

    Schaap, Marcel G. [Univ. of Arizona, Tucson, AZ (United States)


    Carbon capture and storage (CCS) of carbon dioxide emissions generated by production or combustion of fossil fuels is a technologically viable means to reduce the build-up of CO2 in the atmosphere and oceans. Using advantages of scale and location, CCS is particularly suitable for large point sources near ubiquitous deep saline aquifers, depleted gas reservoirs, or at production reservoirs for enhanced oil recovery (EOR). In the BES-funded research project, Oregon State University (OSU) carried out capillary trapping experiments with proxy fluids that mimic the properties of the scCO2/brine system under ambient temperatures and pressures, and successfully developed a unique and novel x-ray compatible, high-pressure, elevated temperature setup to study the scCO2/brine system under challenging reservoir conditions. Both methodologies were applied to a variety of porous media, including synthetic (glass bead) and geologic (Bentheimer sandstone) materials. The University of Arizona (UA) developed pore-scale lattice Boltzmann (LB) models which are able to handle the experimental conditions for proxy fluids, as well as the scCO2/brine system, that are capable of simulating permeability in volumes of tens of millions of fluid elements. We reached the following summary findings (main institute indicated): 1. (OSU/UA) To understand capillary trapping in a multiphase fluid-porous medium system, the system must be analyzed from a pore-scale force balance perspective; trapping can be enhanced by manipulating wetting and nonwetting phase fluid properties. 2. (OSU) Pore-scale fluid connectivity and topology has a clear and direct effect on nonwetting phase capillary trapping efficiency. 3. (OSU) Rock type and flow regime also have a pronounced effects on capillary trapping. 4. (OSU/UA) There is a predictable relationship between NWP connectivity and NWP saturation, which allows for development of injection strategies that optimize trapping. The commonly used Land model (Land

  18. Comparing nanostructured hydroxyapatite coating on AZ91 alloy samples via sol-gel and electrophoretic deposition for biomedical applications. (United States)

    Rojaee, Ramin; Fathi, Mohammadhossein; Raeissi, Keyvan


    Magnesium is one of the most critical elements in hard tissues regeneration and therefore causes speeding up the restoration of harmed bones, while high deterioration rate of magnesium in body fluid restricts it to be used as biodegradable implants. Alloying magnesium with some relatively nobler metals such as aluminium, zinc, rare earth elements, magnesium-bioceramics composites, and surface modification techniques are some of the routes to control magnesium corrosion rate. In this study AZ91 magnesium alloy had been coated by nanostructured hydroxyapatite via sol-gel dip coating and electrophoretical methods to survey the final barricade properties of the obtained coatings. In order to perform electrophoretic coating, powders were prepared by sol-gel method, and then the powders deposited on substrates utilizing direct current electricity. Zeta potentials of the electrophoresis suspensions were measured to determine a best mode for good quality coatings. Transmission Electron Microscopy (TEM), and Scanning Electron Microscopy (SEM) were used to confirm nanoscale dimension, and the uniformity of the nanostructured hydroxyapatite coating, respectively. Fourier Transform-Infrared and X-ray diffraction analysis were utilized for functional group and phase structure evaluation of the prepared coatings, correspondingly. Electrochemical corrosion tests were performed in SBF at 37±1 (°)C which revealed considerable increase in corrosion protection resistivity and corrosion current density for electrophoretic coated specimens versus sol-gel coated specimens. Results showed that both sol-gel and electrophoretical techniques seem to be suitable to coat magnesium alloys for biomedical applications but electrophoretic coating technique is a better choice due to the more homogeneity and more crystalline structure of the coating.


    Directory of Open Access Journals (Sweden)

    A. S. Markova


    Full Text Available The paper describes a clinical case of testicular capillary hemangioma in a 24-year-old man undergone a partial resection of the testis with the intraoperative morphological examination. Testicular capillary hemangioma is a rare benign tumor of a vascular origin, which can be similar to malignant testicular tumors on the clinical presentation, as well as on the imaging methods, in particular to seminoma. The intraoperative histological study can assist in avoiding organ-removing surgical interventions in diagnostically ambiguous cases if a benign testicular tumor is diagnosed.

  20. A novel method for the preparation of electrophoretic display microcapsules

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xiao-Meng; He, Jing; Liu, Sheng-Yun [State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029 (China); Chen, Jian-Feng [State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029 (China); Research Center of the Ministry of Education for High Gravity Engineering and Technology, Beijing University of Chemical Technology, Beijing 100029 (China); Le, Yuan, E-mail: [State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029 (China)


    Highlights: • The electrophoretic display microcapsules were prepared by coaxial jet method aided by gas spray. • The positions of inner tube, liquid and gas flow rate of the process were investigated. • The size and shell thickness of the prepared microcapsules were controllable. • The prepared microcapsules had high coating ratio and exhibit reversible response to DC field. - Abstract: The narrow distributed electrophoretic display microcapsules containing electrophoretic ink were prepared using coaxial jet method aided by gas spray. Experimental results showed the size and shell thickness of the microcapsules could be controlled by adjusting flow rates of core and shell fluids as well as gas. The as-prepared white and red microcapsules, with average size of 100 and 200 μm respectively, had high coating ratio (above 90%) and exhibited reversible response to DC electric field. Compared with the approach of other microencapsulation methods, the new technique not only has a simple procedure but also provides a more effective way of size control. This novel method is expected to prepare microcapsules with potential application in the fields of electronic paper and other material science.

  1. Properties of electrophoretically deposited single wall carbon nanotube films

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Junyoung; Jalali, Maryam; Campbell, Stephen A., E-mail:


    This paper describes techniques for rapidly producing a carbon nanotube thin film by electrophoretic deposition at room temperature and determines the film mass density and electrical/mechanical properties of such films. The mechanism of electrophoretic deposition of thin layers is explained with experimental data. Also, film thickness is measured as a function of time, electrical field and suspension concentration. We use Rutherford backscattering spectroscopy to determine the film mass density. Films created in this manner have a resistivity of 2.14 × 10{sup −3} Ω·cm, a mass density that varies with thickness from 0.12 to 0.54 g/cm{sup 3}, and a Young's modulus between 4.72 and 5.67 GPa. The latter was found to be independent of thickness from 77 to 134 nm. We also report on fabricating free-standing films by removing the metal seed layer under the CNT film, and selectively etching a sacrificial layer. This method could be extended to flexible photovoltaic devices or high frequency RF MEMS devices. - Highlights: • We explain the electrophoretic deposition process and mechanism of thin SWCNT film deposition. • Characterization of the SWCNT film properties including density, resistivity, transmittance, and Young's modulus. • The film density and resistivity are found to be a function of the film thickness. • Techniques developed to create free standing layers of SW-CNTs for flexible electronics and mechanical actuators.

  2. Modeling and experimental study on performance of inverter air conditioner with variation of capillary tube using R-22 and R-407C

    Energy Technology Data Exchange (ETDEWEB)

    Sarntichartsak, Pongsakorn [Faculty of Technology and Management, Prince of Songkla University, Suratthani 84100 (Thailand); Monyakul, Veerapol [National Science and Technology Development Agency (NSTDA), Phathumthani 12120 (Thailand); Thepa, Sirichai [School of Energy and Materials, King Mongkut' s University of Technology Thonburi, Bangmod, Bangkok 10140 (Thailand)


    This paper focuses on an investigation of the proper capillary tube length for an inverter air conditioner. Air to air variable capacity systems with R-22 and R-407C were tested and modeled. First, the optimum refrigerant charge was determined for four capillary tubes at full load condition by varying the mass charge from 1.1 kg to 1.9 kg. The capillary tube lengths were 1.016 m, 0.914 m, 0.813 m and 0.711 m. The two zone model, the distributed model and the combined model were compared to estimate the optimal charge inventory. The combined model analysed a simple path evaporator, a complex path condenser with a two zone model and a distributed model, respectively. It obtained good agreement with experimental results for the system performances and the optimum mass charge. Furthermore, four capillary tubes with specific optimum mass charges were investigated at compressor frequencies in a range of 30-50 Hz. The R-22 capillary tube obtains the best performance with the addition length of 1.016 m at the lowest frequency. Especially, the length of 0.813 m with R-407C is the appropriate size at the operation frequency of 30-35 Hz. The base capillary tube of 0.914 m is optimum at other frequencies. The model prediction agrees with the experimental data in a range of 40-50 Hz. (author)

  3. Phylogenetic relationships among wine yeast strains based on electrophoretic whole-cell protein patterns. (United States)

    Guillamón, J M; Querol, A; Jiménez, M; Huerta, T


    In the present work, a phylogenetic study based on protein electrophoretic profiles of Saccharomyces strains isolated from different Spanish wine regions has been carried out. Qualitative differences between the protein electrophoregrams were found at inter- and intraspecific level, but not between electrophoregrams of strains isolated at the same ecosystem. The numerical analysis of these results allowed us to conclude that intraspecific relationships are determined by ecological factors, as well as human influences (dispersion and artificial selection). A correlation between ecological and/or geographical origin and the relationships among strains was observed.

  4. All solution processed organic thin film transistor-backplane with printing technology for electrophoretic display (United States)

    Lee, Myung W.; Song, C.K.


    In this study, solution processes were developed for backplane using an organic thin film transistor (OTFT) as a driving device for an electrophoretic display (EPD) panel. The processes covered not only the key device of OTFTs but also interlayer and pixel electrodes. The various materials and printing processes were adopted to achieve the requirements of devices and functioning layers. The performance of OTFT of the backplane was sufficient to drive EPD sheet by producing a mobility of 0.12 cm2/v x sec and on/off current ratio of 10(5).

  5. Measurement and evaluation of the relationships between capillary pressure, relative permeability, and saturation for surrogate fluids for laboratory study of geological carbon sequestration (United States)

    Mori, H.; Trevisan, L.; Sakaki, T.; Cihan, A.; Smits, K. M.; Illangasekare, T. H.


    Multiphase flow models can be used to improve our understanding of the complex behavior of supercritical CO2 (scCO2) in deep saline aquifers to make predictions for the stable storage strategies. These models rely on constitutive relationships such as capillary pressure (Pc) - saturation (Sw) and relative permeability (kr) - saturation (Sw) as input parameters. However, for practical application of these models, such relationships for scCO2 and brine system are not readily available for geological formations. This is due to the complicated and expensive traditional methods often used to obtain these relationships in the laboratory through high pressure and/or high-temperature controls. A method that has the potential to overcome the difficulty in conducting such experiments is to replicate scCO2 and brine with surrogate fluids that capture the density and viscosity effects to obtain the constitutive relationships under ambient conditions. This study presents an investigation conducted to evaluate this method. An assessment of the method allows us to evaluate the prediction accuracy of multiphase models using the constitutive relationships developed from this approach. With this as a goal, the study reports multiple laboratory column experiments conducted to measure these relationships. The obtained relationships were then used in the multiphase flow simulator TOUGH2 T2VOC to explore capillary trapping mechanisms of scCO2. A comparison of the model simulation to experimental observation was used to assess the accuracy of the measured constitutive relationships. Experimental data confirmed, as expected, that the scaling method cannot be used to obtain the residual and irreducible saturations. The results also showed that the van Genuchten - Mualem model was not able to match the independently measured kr data obtained from column experiments. Simulated results of fluid saturations were compared with saturation measurements obtained using x-ray attenuations. This

  6. New Sorbent for Bilirubin Removal from Human Plasma: Albumin Immobilized Microporous Membranous PTFE Capillaries

    Institute of Scientific and Technical Information of China (English)

    Lei ZHANG; Gu JIN


    In this study, we developed a tailored capillary sorbent for bilirubin removal. For immobilized bioligand, capillaries were grafted with epoxy groups using RIGP. The HSA immobilized capillaries has a high affinity adsorption capacity (71.2 mg bilirubin/g polymer) and a shorter adsorption equilibrium time (about 60 min).

  7. Comparison of three modifications of fused-silica capillaries and untreated capillaries for protein profiling of maize extracts by capillary electrophoresis. (United States)

    Pobozy, Ewa; Sentkowska, Aleksandra; Piskor, Anna


    In this work, capillary electrophoresis was applied to protein profiling of fractionated extracts of maize. A comparative study on the application of uncoated fused-silica capillaries and capillaries modified with hydroxypropylmethylcellulose, ω-iodoalkylammonium salt and a commercially available neutral capillary covalently coated with polyacrylamide is presented. The coating stability, background electrolyte composition, and separation efficiency were investigated. It was found that for zeins separation, the most stable and efficient was the capillary coated with polyacrylamide. Finally, the usefulness of these methods was studied for the differentiation of zein fraction in transgenic and nontransgenic maize. Zeins extracted from maize standards containing 0 and 5% m/m genetic modification were successfully separated, but slight differences were observed in terms of the zein content. Albumin and globulin fractions were analyzed with the use of unmodified fused-silica capillary with borate buffer pH 9 and the capillary coated with polyacrylamide with phosphate buffer pH 3. In the albumin fraction, additional peaks were found in genetically modified samples.

  8. Capillary condensation between disks in two dimensions

    DEFF Research Database (Denmark)

    Gil, Tamir; Ipsen, John Hjorth


    Capillary condensation between two two-dimensional wetted circular substrates (disks) is studied by an effective free energy description of the wetting interface. The interfacial free-energy potential is developed on the basis of the theory for the wetting of a single disk, where interfacial capi....... The theory can be applied to the description of flocculations in two-dimensional systems of colloids....

  9. Computer-assisted identification of multitrace electrophoretic patterns in differential display experiments. (United States)

    Vähämaa, Heidi; Ojala, Pekka; Pahikkala, Tapio; Nevalainen, Olli S; Lahesmaa, Riitta; Aittokallio, Tero


    Modern multicapillary devices allow researchers to address increasingly complex biological questions involving comparisons of gene expression patterns across electrophoretic samples under various experimental conditions. As labor-intensive visual evaluation of the electrophoretic results is often the bottleneck of large-scale differential display (DD) studies, one way to further streamline this process is to focus only on a highly compressed list of the most potential patterns that are likely to provide reliable findings. To enable the identification of such candidate patterns, we present a computer-assisted method for objective ranking of multitrace peak patterns in DD experiments. The fundamental component of the multitrace pattern ranking method (MRANK) is the multiple alignment algorithm that allows for discovery of patterns involving sets of peak complexes from various electrophoretic samples. A score value is attached to each detected pattern which characterizes how accurately the pattern resembles the desired pattern query, freely defined by the researcher. The ranked pattern list produced by MRANK is validated against visual evaluation in terms of detecting and ranking a group of relevant patterns in a DD analysis of T-helper cell differentiation. We demonstrate high enrichment of the desired patterns on top of the score-ranked list (e.g., 90% of the visually selected patterns are discovered by looking through the first 3% of patterns in the ranked list of all patterns). The results suggest that a substantial amount of manual labor can be saved without compromising the accuracy of the findings by prioritizing the patterns according to MRANK output in the visual confirmation phase.

  10. Recent developments in capillary and chip electrophoresis of bioparticles: Viruses, organelles, and cells. (United States)

    Subirats, Xavier; Blaas, Dieter; Kenndler, Ernst


    In appropriate aqueous buffer solutions, biological particles usually exhibit a particular electric surface charge due to exposed charged or chargeable functional groups (amino acid residues, acidic carbohydrate moieties, etc.). Consequently, these bioparticles can migrate in solution under the influence of an electric field allowing separation according to their electrophoretic mobilities or their pI values. Based on these properties, electromigration methods are of eminent interest for the characterization, separation, and detection of such particles. The present review discusses the research papers published between 2008 and 2010 dealing with isoelectric focusing and zone electrophoresis of viruses, organelles and microorganisms (bacteria and yeast cells) in the capillary and the chip format.

  11. Determination of Labeled Fatty Acids Content in Milk Products, Infant Formula, and Adult/Pediatric Nutritional Formula by Capillary Gas Chromatography: Collaborative Study, Final Action 2012.13. (United States)

    Golay, Pierre-Alain; Moulin, Julie


    A collaborative study was conducted on AOAC First Action Method 2012.13 "Determination of Labeled Fatty Acids Content in Milk Products and Infant Formula by Capillary Gas Chromatography," which is based on an initial International Organization for Standardization (ISO)-International Dairy Federation (IDF) New Work Item that has been moved forward to ISO 16958:2015|IDF 231:2015 in November 2015. It was decided to merge the two activities after the agreement signed between ISO and AOAC in June 2012 to develop common standards and to avoid duplicate work. The collaborative study was performed after having provided highly satisfactory single-laboratory validation results [Golay, P.A., & Dong, Y. (2015) J. AOAC Int. 98, 1679-1696] that exceeded the performance criteria defined in AOAC Standard Method Performance Requirement (SMPR(®)) 2012.011 (September 29, 2012) on 12 products selected by the AOAC Stakeholder Panel on Infant Formula (SPIFAN). After a qualification period of 1 month, 18 laboratories participated in the fatty acids analysis of 12 different samples in duplicate. Six samples were selected to meet AOAC SPIFAN requirements (i.e., infant formula and adult nutritionals in powder and liquid formats), and the other Six samples were selected to meet ISO-IDF requirements (i.e., dairy products such as milk powder, liquid milk, cream, butter, infant formula with milk, and cheese). The fatty acids were analyzed directly in all samples without preliminary fat extraction, except in one sample (cheese). Powdered samples were analyzed after dissolution (i.e., reconstitution) in water, whereas liquid samples (or extracted fat) were analyzed directly. After addition of the internal standards solution [C11:0 fatty acid methyl ester (FAME) and C13:0 triacylglycerols (TAG)] to the samples, fatty acids attached to lipids were transformed into FAMEs by direct transesterification using methanolic sodium methoxide. FAMEs were separated using highly polar capillary GLC and were

  12. Tapered capillary optics (United States)

    Hirsch, Gregory


    A metal or glass wire is etched with great precision into a very narrowly tapering cone which has the shape of the desired final capillary-optics bore. By controlling the rate of removal of the wire from an etchant bath, a carefully controlled taper is produced. A sensor measures the diameter of the wire as it leaves the surface of the etchant. This signal is used for feedback control of the withdrawal speed. The etched wire undergoes a treatment to produce an extremely low surface-roughness. The etched and smoothed wire is coated with the material of choice for optimizing the reflectivity of the radiation being focused. This could be a vacuum evaporation, sputtering, CVD or aqueous chemical process. The coated wire is either electroplated, built up with electroless plating, or encapsulated in a polymer cylinder such as epoxy to increase the diameter of the wire for easier handling and greater robustness. During this process, the wire is vertically oriented and tensioned to assure that the wire is absolutely straight. The coated and electroformed wire is bonded to a flat, rigid substrate and is then periodically segmented by cutting or etching a series of narrow slits or grooves into the wire. The wire is vertically oriented and tensioned during the bonding process to assure that it is straight. The original wire material is then chemically etched away through the slits or otherwise withdrawn to leave the hollow internal bore of the final tapered-capillary optical element.

  13. Capillaries modified by noncovalent anionic polymer adsorption for capillary zone electrophoresis, micellar electrokinetic capillary chromatography and capillary electrophoresis mass spectrometry

    DEFF Research Database (Denmark)

    Bendahl, L; Hansen, S H; Gammelgaard, Bente


    A simple coating procedure for generation of a high and pH-independent electroosmotic flow in capillary zone electrophoresis (CZE) and micellar electrokinetic capillary chromatography (MEKC) is described. The bilayer coating was formed by noncovalent adsorption of the ionic polymers Polybrene...

  14. Electrophoretic deposition of silica-hyaluronic acid and titania-hyaluronic acid nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Ma, R. [Department of Materials Science and Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4L7 (Canada); Zhitomirsky, I., E-mail: [Department of Materials Science and Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4L7 (Canada)


    Research highlights: > The kinetics of electrodeposition of hyaluronic acid has been studied using quartz crystal microbalance. > Composite films containing silica and titania were prepared by electrophoretic deposition. > The deposition yield and deposit composition can be varied by variation of deposition time, voltage and bath composition. > We concluded that the method offers the advantages of room temperature processing for the fabrication of composite materials for biomedical applications. - Abstract: Thin films of hyaluronic acid were prepared by anodic electrophoretic deposition (EPD) and the deposition kinetics was studied using quartz crystal microbalance. EPD method has been developed for the fabrication of new ceramic-biopolymer nanocomposites containing silica and titania nanoparticles in the matrix of hyaluronic acid. The deposit thickness was varied in the range of 0-10 {mu}m. The composition of the deposits can be varied by the variation of silica and titania concentration in the suspensions. The deposits were studied by thermogravimetric analysis, differential thermal analysis, Fourier transform infrared spectroscopy, X-ray diffraction analysis, and scanning electron microscopy. The method offers the advantages of room temperature processing of nanocomposite materials for biomedical applications.

  15. Biomedical applications of capillary electrophoresis (United States)

    Kartsova, L. A.; Bessonova, E. A.


    The review deals with modern analytical approaches used in capillary electrophoresis for solving medical and biological problems: search for biomarkers of various diseases and rapid diagnosis based on characteristic profiles of biologically active compounds by capillary electrophoresis with mass spectrometric detection; monitoring of the residual drugs in biological fluids for evaluating the efficiency of drug therapy; testing of the enantiomeric purity of pharmaceutical products; the use of novel materials as components of stationary and pseudo-stationary phases in capillary electrophoresis and capillary electrochromatography to increase the selectivity of separation of components of complex matrices; and identification of various on-line preconcentration techniques to reduce the detection limits of biologically active analytes. A topical trend in capillary electrophoresis required in clinical practice, viz., the design of microfluidic systems, is discussed. The bibliography includes 173 references.

  16. Chromatographic and electrophoretic assessment of Filgrastim biosimilars in pharmaceutical formulations. (United States)

    Shaltout, Eman L; Al-Ghobashy, Medhat A; Fathalla, Faten A; Salem, Maissa Y


    An orthogonal testing protocol was developed and validated to assess the quality of Filgrastim biosimilars. Results were compared to those obtained from the innovator product. Initial screening was carried out using reducing and non-reducing gel electrophoresis. RP-LC was employed for the determination of Filgrastim in the presence of its oxidative degradation products. SEC and CIEF were used under non-denaturing conditions to reveal high molecular weight and charged impurities, respectively. RP-LC assay was found accurate (99.78±0.89) and precise over a linear concentration range of 9.38-300.00μg/ml with a LOD of 8.26μg/ml (0.44mM). SEC was carried out over a molecular weight range of 5.0-150.0kDa. CIEF was optimized using neutrally coated capillaries over a wide-range pH gradient (pH 3.0-10.0). Differences between the studied products were revealed using all these techniques. Impurities above the acceptable limits were detected in both biosimilar products. CIEF revealed heterogeneity in the active ingredient that has not been investigated by the manufacturers. Correlation of the obtained results indicated the presence of not only product-related impurities, but also process-related impurities. Results confirmed the need for in-house validated orthogonal testing protocols to be developed by local regulatory authorities. This should prevent access of substandard biosimilars to price-sensitive markets.

  17. Capillary method for measuring near-infrared spectra of microlitre volume liquids

    Institute of Scientific and Technical Information of China (English)

    YUAN Bo; MURAYAMA Koichi


    The present study theoretically explored the feasibility of the capillary method for measuring near-infrared (NIR) spectra of liquid or solution samples with microlitre volume, which was proposed in our previous studies. Lambert-Beer absorbance rule was applied to establish a model for the integral absorbance of capillary, which was then implemented in numerical analyses of the effects of capillary on various spectral features and dynamic range of absorption measurement. The theoretical speculations indicated that the capillary method might be used in NIR spectroscopy, which was further supported by the empirical data collected from our experiments by comparison between capillary NIR spectra of several organic solvents and cuvette cell NIR spectra.

  18. Experimental study of the impact of antimicrobial treatments on Campylobacter, Enterococcus and PCR-capillary electrophoresis single-strand conformation polymorphism profiles of the gut microbiota of chickens. (United States)

    Mourand, Gwenaëlle; Jouy, Eric; Bougeard, Stéphanie; Dheilly, Alexandra; Kérouanton, Annaëlle; Zeitouni, Salman; Kempf, Isabelle


    An experiment was conducted to compare the impact of antimicrobial treatments on the susceptibility of Campylobacter, Enterococcus faecium and Enterococcus faecalis, and on the diversity of broiler microbiota. Specific-pathogen-free chickens were first orally inoculated with strains of Campylobacter and Enterococcus faecium. Birds were then orally treated with recommended doses of oxytetracycline, sulfadimethoxine/trimethoprim, amoxicillin or enrofloxacin. Faecal samples were collected before, during and after antimicrobial treatment. The susceptibility of Campylobacter, Enterococcus faecium and Enterococcus faecalis strains isolated on supplemented or non-supplemented media was studied and PCR-capillary electrophoresis single-strand conformation polymorphism (CE-SSCP) profiles of the gut microbiota were analysed. Enrofloxacin-resistant Campylobacter were selected in the enrofloxacin-treated group and showed the Thr86Ile mutation in the gyrA gene. Acquisition of the tetO gene in Campylobacter coli isolates was significantly more frequent in birds given oxytetracycline. No impact of amoxicillin treatment on the susceptibility of Campylobacter could be detected. Ampicillin- and sulfadimethoxine/trimethoprim-resistant Enterococcus faecium were selected in amoxicillin-treated broilers, but no selection of the inoculated vancomycin-resistant Enterococcus faecium could be detected, although it was also resistant to tetracycline and sulfadimethoxine/trimethoprim. PCR-CE-SSCP revealed significant variations in a few peaks in treated birds as compared with non-treated chickens. In conclusion, antimicrobial treatments perturbed chicken gut microbiota, and certain antimicrobial treatments selected or co-selected resistant strains of Campylobacter and Enterococcus.

  19. Comparative Study of Three Methods for Affinity Measurements: Capillary Electrophoresis Coupled with UV Detection and Mass Spectrometry, and Direct Infusion Mass Spectrometry (United States)

    Mironov, Gleb G.; Logie, Jennifer; Okhonin, Victor; Renaud, Justin B.; Mayer, Paul M.; Berezovski, Maxim V.


    We present affinity capillary electrophoresis and mass spectrometry (ACE-MS) as a comprehensive separation technique for label-free solution-based affinity analysis. The application of ACE-MS for measuring affinity constants between eight small molecule drugs [ibuprofen, s-flurbiprofen, diclofenac, phenylbutazone, naproxen, folic acid, resveratrol, and 4,4'-(propane-1,3-diyl) dibenzoic acid] and β-cyclodextrin is described. We couple on-line ACE with MS to combine the separation and kinetic capability of ACE together with the molecular weight and structural elucidation of MS in one system. To understand the full potential of ACE-MS, we compare it with two other methods: Direct infusion mass spectrometry (DIMS) and ACE with UV detection (ACE-UV). After the evaluation, DIMS provides less reliable equilibrium dissociation constants than separation-based ACE-UV and ACE-MS, and cannot be used solely for the study of noncovalent interactions. ACE-MS determines apparent dissociation constants for all reacting small molecules in a mixture, even in cases when drugs overlap with each other during separation. The ability of ACE-MS to interact, separate, and rapidly scan through m/z can facilitate the simultaneous affinity analysis of multiple interacting pairs, potentially leading to the high-throughput screening of drug candidates.

  20. Vitrification by ultra-fast cooling at a low concentration of cryoprotectants in a quartz micro-capillary: a study using murine embryonic stem cells. (United States)

    He, Xiaoming; Park, Eric Y H; Fowler, Alex; Yarmush, Martin L; Toner, Mehmet


    Conventional cryopreservation protocols for slow-freezing or vitrification involve cell injury due to ice formation/cell dehydration or toxicity of high cryoprotectant (CPA) concentrations, respectively. In this study, we developed a novel cryopreservation technique to achieve ultra-fast cooling rates using a quartz micro-capillary (QMC). The QMC enabled vitrification of murine embryonic stem (ES) cells using an intracellular cryoprotectant concentration in the range used for slowing freezing (1-2M). The cryoprotectants used included 2M 1,2-propanediol (PROH, cell membrane permeable) and 0.5M extracellular trehalose (cell membrane impermeable). More than 70% of the murine ES cells post-vitrification attached with respect to non-frozen control cells, and the proliferation rates of the two groups were similar. Preservation of undifferentiated properties of the pluripotent murine ES cells post-vitrification cryopreservation was verified using three different types of assays: the expression of transcription factor Oct-4, the presentation of the membrane surface glycoprotein SSEA-1, and the elevated expression of the intracellular enzyme alkaline phosphatase. These results indicate that vitrification at a low concentration (2M) of intracellular cryoprotectants is a viable and effective approach for the cryopreservation of murine embryonic stem cells.

  1. In-house-made capillary electrophoresis instruments coupled with contactless conductivity detection as a simple and inexpensive solution for water analysis: a case study in Vietnam. (United States)

    Duong, Hong Anh; Le, Minh Duc; Nguyen, Kim Diem Mai; Hauser, Peter C; Pham, Hung Viet; Mai, Thanh Duc


    A simple and inexpensive method for the determination of various ionic species in different water matrices is discussed in this study. The approach is based on the employment of in-house-made capillary electrophoresis (CE) instruments with capacitively coupled contactless conductivity detection (C(4)D), which can be realized even when only a modest financial budget and limited expertise are available. Advantageous features and considerations of these instruments are detailed following their pilot deployment in Vietnam. Different categories of ionic species, namely major inorganic cations (K(+), Na(+), Ca(2+), Mg(2+), and NH4(+)) and major inorganic anions (Cl(-), NO3(-), NO2(-), SO4(2-), and phosphate), in different water matrices in Vietnam were determined using these in-house fabricated instruments. Inorganic trivalent arsenic (As(iii)), which is the most abundant form of arsenic in reducing groundwater, was determined by CE-C(4)D. The effect of some interfering ions in groundwater on the analytical performance was investigated and is highlighted. The results from in-house-made CE-C(4)D-instruments were cross-checked with those obtained using the standard methods (AAS, AES, UV and IC), with correlation coefficients r(2) ≥ 0.9 and deviations from the referenced results less than 15%.

  2. 亲和毛细管电泳、环糊精-电动色谱、毛细管电泳-质谱用于对映体分离的研究进展%Method Development of Enantiomer Separations by Affinity Capillary Electrophoresis,Cyclodextrin Electrokinetic Chromatography and Capillary Electrophoresis-Mass Spectrometry

    Institute of Scientific and Technical Information of China (English)


    Capillary electrophoresis (CE) has become a powerful tool for enantiomer separat ions during the last decade. Since 1993, the author has investigated enantiomer separations by affinity capillary electrophoresis (affinity CE) with some prote ins and by cyclodextrin electrokinetic chromatography (CDEKC) with some charged cyclodextrins (CDs). Many successful enantiomer separations are demonstrated f rom our study in this review article. In the enantiomer separations by affinit y CE, the deterioration of detection sensitivity was observed under high concent ration of the protein in running solutions. The partial filling technique was practically useful to solve the serious problem. It allowed operation at high protein concentrations, such as 500 μmol/L, without the detection problem. Cha rged CDs had several advantages for the enantiomer separations over neutral ones . Strong electrostatic interactions between a charged CD and oppositely charged analytes should be effective for the formation of the complex. A large differen ce in electrophoretic mobility between the free analyte and the inclusion comple x should also enhance the enantiomeric resolution. In CEmass spectrometry (CE MS), the partial filling technique was applied to avoid the introduction of no nvolatile chiral selectors into the CEMS interface. By replacing the nonvolat ile electrolytes in the running buffer by volatile ones, the separation conditio ns employed in CE with the UV detection method could be transferred to CEMS.

  3. Macroscopic theory for capillary-pressure hysteresis. (United States)

    Athukorallage, Bhagya; Aulisa, Eugenio; Iyer, Ram; Zhang, Larry


    In this article, we present a theory of macroscopic contact angle hysteresis by considering the minimization of the Helmholtz free energy of a solid-liquid-gas system over a convex set, subject to a constant volume constraint. The liquid and solid surfaces in contact are assumed to adhere weakly to each other, causing the interfacial energy to be set-valued. A simple calculus of variations argument for the minimization of the Helmholtz energy leads to the Young-Laplace equation for the drop surface in contact with the gas and a variational inequality that yields contact angle hysteresis for advancing/receding flow. We also show that the Young-Laplace equation with a Dirichlet boundary condition together with the variational inequality yields a basic hysteresis operator that describes the relationship between capillary pressure and volume. We validate the theory using results from the experiment for a sessile macroscopic drop. Although the capillary effect is a complex phenomenon even for a droplet as various points along the contact line might be pinned, the capillary pressure and volume of the drop are scalar variables that encapsulate the global quasistatic energy information for the entire droplet. Studying the capillary pressure versus volume relationship greatly simplifies the understanding and modeling of the phenomenon just as scalar magnetic hysteresis graphs greatly aided the modeling of devices with magnetic materials.

  4. Capillary Discharge XUV Radiation Source

    Directory of Open Access Journals (Sweden)

    M. Nevrkla


    Full Text Available A device producing Z-pinching plasma as a source of XUV radiation is described. Here a ceramic capacitor bank pulse-charged up to 100 kV is discharged through a pre-ionized gas-filled ceramic tube 3.2 mm in diameter and 21 cm in length. The discharge current has amplitude of 20 kA and a rise-time of 65 ns. The apparatus will serve as experimental device for studying of capillary discharge plasma, for testing X-ray optics elements and for investigating the interaction of water-window radiation with biological samples. After optimization it will be able to produce 46.9 nm laser radiation with collision pumped Ne-like argon ions active medium. 

  5. Electrophoretic Deposition of Carbon Nanotubes on 3-Amino-Propyl-Triethoxysilane (APTES Surface Functionalized Silicon Substrates

    Directory of Open Access Journals (Sweden)

    Theda Daniels-Race


    Full Text Available Fabrication of uniform thin coatings of multi-walled carbon nanotubes (MWCNTs by electrophoretic deposition (EPD on semiconductor (silicon substrates with 3-aminopropyl-triethoxysilane (APTES surface functionalization has been studied extensively in this report. The gradual deposition and eventual film formation of the carbon nanotubes (CNTs is greatly assisted by the Coulombic force of attraction existing between the positively charged –NH2 surface groups of APTES and the acid treated, negatively charged nanotubes migrating towards the deposition surfaces. The remarkable deposition characteristics of the CNT coatings by EPD in comparison to the dip coating method and the influence of isopropyl (IPA-based CNT suspension in the fabricated film quality has also been revealed in this study. The effect of varying APTES concentration (5%–100% on the Raman spectroscopy and thickness of the deposited CNT film has been discussed in details, as well. The deposition approach has eliminated the need of metal deposition in the electrophoretic deposition approach and, therefore, establishes a cost-effective, fast and entirely room temperature-based fabrication strategy of CNT thin films for a wide range of next generation electronic applications.

  6. Characterization of CNT-MnO2 nanocomposite by electrophoretic deposition as potential electrode for supercapacitor (United States)

    Darari, Alfin; Ardiansah, Hafidh Rahman; Arifin, Rismaningsih, Nurmanita; Ningrum, Andini Novia; Subagio, Agus


    Energy crisis that occured in Indonesia suggests that energy supply could not offset the high rate request and needs an electric energy saving device which can save high voltage, safety, and unlimited lifetime. The weakness of batteries is durable but has a low power density while the capacitor has a high power density but it doesn't durable. The renewal of this study is CNT-MnO2 thin film fabrication method using electrophoretic deposition. Electrophoretic deposition is a newest method to deposited CNT using power supply with cheap, and make a good result. The result of FTIR analysis showed that the best CNT-MnO2 composition is 75:25 and C-C bond is detected in fingerprint area. The result is electrode thin film homogen and characterized by X-ray diffraction (XRD) peaks 2θ=26,63° is characterization of graphite, and 2θ=43,97° is characterization of diamond Carbon type and measured by Scherrer formula results 52,3 nm material average size .EIS test results its capacitance about 7,86 F. from the data it can be concluded that CNT-MnO2 potential electrode very promising for further study and has a potential to be a high capacitance, and fast charge supercapacitor which can be applied for electronic devices, energy converter, even electric car.

  7. Electrophoretic deposition of composite halloysite nanotube–hydroxyapatite–hyaluronic acid films

    Energy Technology Data Exchange (ETDEWEB)

    Deen, I. [Department of Materials Science and Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4L7 (Canada); Zhitomirsky, I., E-mail: [Department of Materials Science and Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4L7 (Canada)


    Highlights: ► Composite halloysite nanotubes–hydroxyapatite–hyaluronic acid films were prepared. ► Electrophoretic deposition method was used for deposition. ► Natural hyaluronic acid was used as a dispersing, charging and film forming agent. ► Film composition and deposition yield can be varied. ► The films can be used for biomedical implants with controlled release of drugs. -- Abstract: Electrophoretic deposition method has been developed for the deposition of biocomposite films containing halloysite nanotubes (HNTs), hydroxyapatite (HA) and hyaluronic acid. The method is based on the use of natural hyaluronate biopolymer as a dispersing and charging agent for HNT and HA and film forming agent for the fabrication of the composite films. The deposition kinetics was studied by the quartz crystal microbalance method. The composite films were studied by X-ray diffraction, thermogravimetric analysis, differential thermal analysis and electron microscopy. The composite films are promising materials for the fabrication of biomedical implants with advanced functional properties.

  8. Nano-structured yttria-stabilized zirconia coating by electrophoretic deposition

    Energy Technology Data Exchange (ETDEWEB)

    Maleki-Ghaleh, H., E-mail: [Faculty of Materials Engineering, Sahand University of Technology, Tabriz (Iran, Islamic Republic of); Rekabeslami, M. [Faculty of Mechanical Engineering, Materials Science and Engineering Division, K. N. Toosi University of Technology, Tehran (Iran, Islamic Republic of); Shakeri, M.S. [Materials and Energy Research Center, Karaj (Iran, Islamic Republic of); Siadati, M.H. [Faculty of Mechanical Engineering, Materials Science and Engineering Division, K. N. Toosi University of Technology, Tehran (Iran, Islamic Republic of); Javidi, M. [Department of Materials Science and Engineering, School of Engineering, Shiraz University, Shiraz (Iran, Islamic Republic of); Talebian, S.H. [Faculty of Petroleum Engineering, Universiti Technologi Petronas, Perak (Malaysia); Aghajani, H. [Department of Materials Engineering, University of Tabriz, Tabriz (Iran, Islamic Republic of)


    The most important role of thermal barrier coatings is to reduce the temperature of the substrate in high temperature applications. Nanoparticle zirconia might be a suitable choice for improving the efficiency of thermal barrier coatings. Nanostructured coatings have lower thermal conduction, higher thermal expansion and lower dimensional variations at higher temperatures in comparison with the microstructured coatings. Electrophoretic deposition has been preferred for thermal barrier coatings due to its simplicity, controllability and low cost. In the present study, three different suspensions of ZrO{sub 2}–8 wt%Y{sub 2}O{sub 3} (40 nm) made with ethanol, acetone and acetyl acetone were used. Electrophoretic deposition was conducted at a fixed voltage of 60 V for 120 s on aluminized Inconel 738-LC, and then heat treated at 1100{sup o}C for 4 h in air atmosphere. The coating morphology and elemental distribution were studied using scanning electron microscopy. It was observed that suspension media have an important effect on the quality of the final product. Acetyl acetone showed better dispersion of particles than the other two media. Consequently, deposition from acetyl acetone resulted in uniform and crack-free layers while those from ethanol and acetone were completely non-uniform due to agglomeration and low viscosity, respectively.

  9. Decisive influence of colloidal suspension conductivity during electrophoretic impregnation of porous anodic film supported on 1050 aluminium substrate. (United States)

    Fori, B; Taberna, P L; Arurault, L; Bonino, J P


    The present paper studies the influence of suspension conductivity on the electrophoretic deposition (EPD) of nanoparticles inside a porous anodic aluminium oxide film. It is shown that an increase in the suspension's conductivity enhances impregnation of the anodic film by the nanoparticles. Two mechanisms are seen to promote the migration of particles into the pores. Indeed an increase in the suspension conductivity leads on the one hand to a strengthening of the electric field in the anodic film and on the other hand to a thinning of the electric double layer on the pore walls. The results of our study confirm that colloidal suspension conductivity is a key parameter governing the electrophoretic impregnation depth.

  10. Variations in virulence between different electrophoretic types of Listeria monocytogenes

    DEFF Research Database (Denmark)

    Nørrung, Birgit; Andersen, Jens Kirk


    A total of 245 strains of Listeria monocytogenes, representing 33 different electrophoretic types (ETs), were examined quantitatively for haemolytic activity. No significant difference was observed in the mean haemolytic activity between different ETs. Eighty four out of 91 strains examined were...... compared with 3.64 among food isolates). The explanation for this may be that more virulent strains are more prone to cause human infection. It is, however, also possible that strains oft. monocytogenes may become more virulent while multiplying in a living organism compared with multiplying in foods....

  11. Electrophoretic Partitioning of Proteins in Two-Phase Microflows

    DEFF Research Database (Denmark)

    Münchow, G.; Hardt, S.; Kutter, Jörg Peter


    conductor and decouples the channel from the electrodes, thus preventing bubble generation inside the separation channel. The experiments show that the electrophoretic transport of proteins between the laminated liquid phases is characterized by a strong asymmetry. When bovine serum albumin (BSA...... control of the formation and arrangement of liquid/liquid phase boundaries. The two immiscible phases which are injected separately into the microchannel are taken from a polyethylene glycol (PEG)-dextran system. The side walls of the channel are partially made of gel material which serves as an ion...

  12. Multidimensional capillary electrophoresis. (United States)

    Grochocki, Wojciech; Markuszewski, Michał J; Quirino, Joselito P


    Multidimensional separation where two or more orthogonal displacement mechanisms are combined is a promising approach to increase peak capacity in CE. The combinations allow dramatic improvement of analytical performance since the total peak capacity is given by a product of the peak capacities of all methods. The initial reports were concentrated on the construction of effective connections between capillaries for 2D analysis. Today, 2D and 3D CE systems are now able to separate real complex biological or environmental mixtures with good repeatability, improved resolution with minimal loss of sample. This review will present the developments in the field of multidimensional CE during the last 15 years. The endeavors in this specific field were on the development of interfaces, interface-free techniques including integrated separations, microdevices, and on-line sample concentration techniques to improve detection sensitivity.

  13. Review of UV spectroscopic, chromatographic, and electrophoretic methods for the cholinesterase reactivating antidote pralidoxime (2-PAM). (United States)

    John, Harald; Blum, Marc-Michael


    Pralidoxime (2-PAM) belongs to the class of monopyridinium oximes with reactivating potency on cholinesterases inhibited by phosphylating organophosphorus compounds (OPC), for example, pesticides and nerve agents. 2-PAM represents an established antidote for the therapy of anticholinesterase poisoning since the late 1950s. Quite high therapeutic concentrations in human plasma (about 13 µg/ml) lead to concentrations in urine being about 100 times higher allowing the use of less sensitive analytical techniques that were used especially in the early years after 2-PAM was introduced. In this time (mid-1950s until the end of the 1970s) 2-PAM was most often analyzed by either paper chromatography or simple UV spectroscopic techniques omitting any sample separation step. These methods were displaced completely after the establishment of column liquid chromatography in the early 1980s. Since then, diverse techniques including cation exchange, size-exclusion, reversed-phase, and ligand-exchange chromatography have been introduced. Today, the most popular method for 2-PAM quantification is ion pair chromatography often combined with UV detection representing more than 50% of all column chromatographic procedures published. Furthermore, electrophoretic approaches by paper and capillary zone electrophoresis have been successfully used but are seldom applied. This review provides a commentary and exhaustive summary of analytical techniques applied to detect 2-PAM in pharmaceutical formulations and biological samples to characterize stability and pharmacokinetics as well as decomposition and biotransformation products. Separation techniques as well as diverse detectors are discussed in appropriate detail allowing comparison of individual preferences and limitations. In addition, novel data on mass spectrometric fragmentation of 2-PAM are provided.

  14. Finding the "bio" in biobased products: electrophoretic identification of wheat proteins in processed products. (United States)

    Robertson, George H; Hurkman, William J; Cao, Trung K; Tanaka, Charlene K; Orts, William J


    Verification of the biocontent in biobased or "green" products identifies genuine products, exposes counterfeit copies, supports or refutes content claims, and ensures consumer confidence. When the biocontent includes protein, elemental nitrogen analysis is insufficient for verification since non-protein, but nitrogen-rich, content also may be present. However, the proteins can be extracted, separated by electrophoretic methods, and detected by UV absorption, protein stain, or immunoblotting. We utilized capillary zone electrophoresis (CZE) to separate proteins in a gliadin fraction that had been dissolved in aqueous ethanol (70%) and polyacrylamide gel electrophoresis (PAGE) to separate proteins in a gliadin-plus-glutenin fraction that had been dissolved in water containing both sodium dodecyl sulfate (SDS) and a reducing agent, dithiothreitol (DTT). We sought to verify the presence of these wheat grain proteins in wheat bread, a wheat flake cereal, wheat beer, and an enclosure for an antique automobile ignition coil reputed to contain wheat gluten. Proteins extracted from commercial wheat, corn, and soy flours served as standards, and proteins from heat-altered wheat served as process condition references. This approach successfully identified wheat proteins in these products especially if the process temperature did not exceed 120 degrees C. Above this temperature attenuation was nearly complete for proteins analyzed by CZE, but wheat-like patterns could still be recognized by one- and two-dimensional PAGE. Immunoblots reacted with grain-specific antibodies confirmed the identities of the cereal component especially when the protein pattern was greatly altered by thermal modification, specific protein adsorption, or protein digestion. In addition to verifying that wheat proteins are present, the complementary use of these methods can reveal whether whole wheat gluten or merely an alcohol-soluble fraction had been used in the specific product and indicate the

  15. Calculation Metho d of Power Law Fluid Equivalent Permeability Considering Capillary Shap e

    Institute of Scientific and Technical Information of China (English)

    YANG Er-long; LI Huan; GAO Hui-juan; GU Ting-ting


    While studying the flow of oil and gas in the reservoir, it is not realistic that capillary with circular section is only used to express the pores. It is more representative to simulate porous media pore with kinds of capillary with triangle or rectangle section etc. In the condition of the same diameter, when polymer for oil displacement flows in the porous medium, there only exists shear flow which can be expressed with power law model. Based on fluid flow-pressure drop equation in single capillary, this paper gives a calculation method of equivalent permeability of power law fluid of single capillary and capillary bundles with different sections.

  16. Preparation and characterization of TiO 2-cationic hybrid nanoparticles as electrophoretic particles (United States)

    Li, Jingjing; Deng, Liandong; Xing, Jinfeng; Dong, Anjie; Li, Xianggao


    The hybrid nanoparticles (TiO2-HNPs) with TiO2 nanoparticles as core and with poly(N,N-dimethylaminoethyl methacrylate-co-methyl methacrylate) by using triallylamine as cross-linking agent as shell were firstly prepared via atom transfer radical polymerization (ATRP) in methanol. Then the hybrid nanoparticles with positive charge were produced by the quaternization with methyl iodide as quaternization reagent so as to endow them with greater electrophoretic mobility. The cationic hybrid nanoparticles (TiO2-CHNPs) were studied by means of transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy and dynamic light scattering (DLS) measurements. The results indicate that the cationic polymer is successfully grafted on the surface of the TiO2 nanoparticles. The particle size of TiO2-CHNPs is about 150 nm and the polydispersity index (PDI) is 0.307. The zeta potential, the contrast ratio of white state to dark state and response time of TiO2-CHNPs are +16.8 mV, 30 and 3 s, respectively, which show the potential application prospect in the development of electrophoretic ink.

  17. Physical investigation of electrophoretically deposited graphene oxide and reduced graphene oxide thin films (United States)

    Politano, Grazia Giuseppina; Versace, Carlo; Vena, Carlo; Castriota, Marco; Ciuchi, Federica; Fasanella, Angela; Desiderio, Giovanni; Cazzanelli, Enzo


    Graphene oxide and reduced graphene oxide thin films are very promising materials because they can be used in optoelectronic devices and in a growing range of applications such as touch screens and flexible displays. In this work, graphene oxide (GO) and thermally reduced graphene oxide (rGO) thin films, deposited on Ti/glass substrates, have been obtained by electrophoretic deposition. The morphological and the structural properties of the samples have been investigated by micro-Raman technique, X-ray reflectometry, and SEM analysis. In order to study the optical and electrical properties, variable angle spectroscopic ellipsometry and impedance analysis have been performed. The thermal annealing changes strongly the structural, electrical, and optical properties, because during the thermal processes some amount of sp3 bonds originally present in GO were removed. In particular, the annealing enhances the Ohmic behavior of the rGO film increasing its conductivity and the estimated optical density. Moreover, using electrophoretic deposition, we have found a higher value of optical density for GO thin films, not observed in GO films obtained with other deposition methods.

  18. Electrophoretic Ink Display Prepared by Jelly Fig Pectin/Gelatin Microspheres

    Directory of Open Access Journals (Sweden)

    Wing-Ming Chou


    Full Text Available A brand new Bio-Electronic ink (Bio-E ink display device was prepared and characterized in this study. Semiconductor material, copper phthalocyanine (CuPc was modified by cationic surfactants, cetylpyridinium chloride (CPC, as the core material, and the shell of capsule was prepared by jelly fig pectin, gelatin and sodium dodecyl sulphate (SDS. Here, jelly fig pectin was provided as the shell material for the first time. Chemical structure of the modified CuPc was characterized by Fourier Transform Infrared Spectrometer (FTIR. The core-shell microcapsules were achieved by coacervation method in an oil/water (O/W emulsion system. The particle size and morphology of microcapsules were affected by the concentrations of SDS and pH values of the O/W emulsion system. A new microcapsule-based electrophoretic display device was presented. Its image display ability of the microcapsules electrophoretic device was presented as appropriated electric power was applied, and the response time was 0.06 sec under 0.1 V/mm of electric field. Moreover, we found that its image contrast ratio of display device was influenced by the particle sizes of the microcapsules.

  19. Analysis of In Vitro DNA Interactions of Brassinosteroid-Controlled Transcription Factors Using Electrophoretic Mobility Shift Assay. (United States)

    Unterholzner, Simon J; Rozhon, Wilfried; Poppenberger, Brigitte


    Most signaling cascades ultimately lead to changes in gene expression by modulating the activity of transcription factors (TFs). The electrophoretic mobility shift assay (EMSA) is a simple but powerful in vitro method for investigation of specific protein-DNA interactions. It makes use of the fact that protein-DNA complexes have a lower electrophoretic mobility in gels than free DNA has. The application of labeled probes in combination with unlabeled competitors allows investigation of DNA-binding specificity and identification of binding motifs with single base-pair resolution. Here we describe the application of EMSAs for the study of interactions of the brassinosteroid-regulated TFs, BRASSINAZOLE-RESISTANT1, (BZR1), BRI1-ETHYL METHANESULFONATE-SUPPRESSOR1 (BES1)/BZR2, and CESTA with putative binding sites. The classical approach using radiolabeled probes, as well as the more recent application of fluorescent probes, is described and the advantages and disadvantages of both methods are discussed.

  20. The coupling of capillary electrophoresis-inductively coupled plasma mass spectrometer as a speciation instrument for actinides at trace level; Le couplage electrophorese capillaire-spectrometre de masse a source plasma en tant qu'instrument de speciation des actinides a l'etat de traces

    Energy Technology Data Exchange (ETDEWEB)

    Delorme, A


    An interface between the separation technique (capillary electrophoresis) and the analytical technique (Inductively Coupled Plasma - Mass Spectrometer) was developed. In that sense, bibliographic and parametric studies allowed to define necessary conditions for the good working of both techniques. The results obtained led to the realisation of an interface capillary electrophoresis / ICP-MS (CE / ICP-MS). This one was experimentally validated on classical separations (alkalis / earth-alkalis and lanthanides) and the detection limit of the analytical system was determined equal to 4 x 10{sup -11} mol.L{sup -1} for plutonium. This result exhibits a gain in detection limit of a factor higher than 10{sup 4} compared to the capillary electrophoresis in standard detection (UV). The studies were made in order to check the capacity of the CE / ICP-MS coupling as a speciation instrument for actinides at trace level and to define the associated analytical procedures. The coupling turned out to be a suited instrument for the determination of absolute electrophoretic mobilities at infinite dilution (physico-chemical property which allows to predict the migration time of an ion under an electrical field in a given electrolyte), for the determination of thermodynamic constants and for the separation of different actinide oxidation states in solution. (author)

  1. Formation of TiO2 photoanodes by simultaneous electrophoretic deposition of anatase and rutile particles for photoassisted electrolytic copper ions removal

    Directory of Open Access Journals (Sweden)

    Yeimmy Y. Peralta-Ruiz


    Full Text Available The influence of Anatasa/Rutile ratio on TiO2 films, grown by electrophoretic deposition was studied in the photoassisted electrolytic copper ions removal from cyanide solutions. The proper dispersant dosage allowing the simultaneous electrophoretic deposition of Anatase and Rutile was chosen based on electrokinetic measurements; evidenced by the XRD spectra of the formed films. The evaluation of films photoassisted electrolytic copper ion removal showeds that it is possible to enhance the activity of Anatase films by adding some Rutile exploiting the synergetic interaction between these two materials, achieve by its proper deposition.

  2. Recent innovations in protein separation on microchips by electrophoretic methods. (United States)

    Peng, Youyuan; Pallandre, Antoine; Tran, N Thuy; Taverna, Myriam


    Microchips for analytical purposes have attracted great attention over the last 20 years. In the present review, we focus on the most recent development of microchips for electrophoretic separation of proteins. This review starts with a short recalling about the microchips covering the basic microchip layout for CE and the commercial chips and microchip platforms. A short paragraph is dedicated to the surface treatment of microchips, which is of paramount importance in protein analysis. One section is dedicated to on-line sample pretreatment in microchips and summarizes different strategies to pre-concentrate or to purify proteins from complex matrixes. Most of the common modes used for CE of proteins have already been adapted to the chip format, while multidimensional approaches are still in progress. The different routes to achieve detection in microchip are also presented with a special attention to derivatization or labeling of proteins. Finally, several recent applications are mentioned. They highlight the great potential of electrophoretic separations of proteins in numerous fields such as biological, pharmaceutical or agricultural and food analysis. A bibliography with 151 references is provided covering papers published from 2000 to the early 2007.

  3. Capillary flow solder wettability test

    Energy Technology Data Exchange (ETDEWEB)

    Vianco, P.T.; Rejent, J.A.


    A test procedure was developed to assess the capillary flow wettability of solders inside of a confined geometry. The test geometry was comprised of two parallel plates with a controlled gap of constant thickness (0.008 cm, 0.018 cm, 0.025 cm, and 0.038 cm). Capillary flow was assessed by: (1) the meniscus or capillary rise of the solder within the gap, (2) the extent of void formation in the gap, and (3) the time-dependence of the risen solder film. Tests were performed with the lead-free solders.

  4. Capillary dynamics driven by molecular self-layering. (United States)

    Wu, Pingkeng; Nikolov, Alex; Wasan, Darsh


    Capillary dynamics is a ubiquitous everyday phenomenon. It has practical applications in diverse fields, including ink-jet printing, lab-on-a-chip, biotechnology, and coating. Understanding capillary dynamics requires essential knowledge on the molecular level of how fluid molecules interact with a solid substrate (the wall). Recent studies conducted with the surface force apparatus (SFA), atomic force microscope (AFM), and statistical mechanics simulation revealed that molecules/nanoparticles confined into the film/wall surfaces tend to self-layer into 2D layer/s and even 2D in-layer with increased confinement and fluid volume fraction. Here, the capillary rise dynamics of simple molecular fluids in cylindrical capillary is explained by the molecular self-layering model. The proposed model considers the role of the molecular shape on self-layering and its effect on the molecularly thin film viscosity in regards to the advancing (dynamic) contact angle. The model was tested to explain the capillary rise dynamics of fluids of spherical, cylindrical, and disk shape molecules in borosilicate glass capillaries. The good agreement between the capillary rise data and SFA data from the literature for simple fluid self-layering shows the validity of the present model. The present model provides new insights into the design of many applications where dynamic wetting is important because it reveals the significant impact of molecular self-layering close to the wall on dynamic wetting.

  5. Converging of Argon Cluster Ion Beams with a Glass Capillary (United States)

    Shoji, Kazuhiro; Iuchi, Kensuke; Izumi, Motoki; Moritani, Kousuke; Inui, Norio; Mochiji, Kozo

    We have investigated the converging behavior of argon gas cluster ion beam passed through a glass capillary. The gas cluster ions are attractive as a projectile for SIMS from the view point of minimization of the damages. The cluster ion beam of 5 keV consisting of 500˜3000 argon atoms was injected in the capillary. The inner diameters of the capillary at the inlet and outlet were 0.8 mm and 9.6˜140 μm, respectively. Ion current from the outlet of the all the capillaries were detected. We obtained the converging factor of 2˜7, which depended on the incident ion current. The kinetic energy of the incident ions was found to be reduced by 20˜30% by passing through the capillary. Contrary, the velocity of the ions was not changed. These facts suggest that the cluster becomes 20˜30% smaller in mass by passing through the capillary. As far as we know, this is the first report on the study of the converging of cluster ions by using a glass capillary.

  6. Capillary climb dynamics in the limits of prevailing capillary and gravity force. (United States)

    Bijeljic, B; Markicevic, B; Navaz, H K


    The dynamics of capillary climb of a wetting liquid into a porous medium that is opposed by gravity force is studied numerically. We use the capillary network model, in which an actual porous medium is represented as a network of pores and throats, each following a predefined size distribution function. The liquid potential in the pores along the liquid interface within the network is calculated as a result of capillary and gravity forces. The solution is general, and accounts for changes in the climbing height and climbing velocity. The numerical results for the capillary climb reveal that there are at least two distinct flow mechanisms. Initially, the flow is characterized by high climbing velocity, in which the capillary force is higher than the gravity force, and the flow is the viscous force dominated. For this single-phase flow, the Washburn equation can be used to predict the changes of climbing height over time. Later, for longer times and larger climbing height, the capillary and gravity forces become comparable, and one observes a slower increase in the climbing height as a function of time. Due to the two forces being comparable, the gas-liquid sharp interface transforms into flow front, where the multiphase flow develops. The numerical results from this study, expressed as the climbing height as a power law function of time, indicate that the two powers, which correspond to the two distinct mechanisms, differ significantly. The comparison of the powers with experimental data indicates good agreement. Furthermore, the power value from the Washburn solution is also analyzed, where it should be equal to 1/2 for purely viscous force driven flow. This is in contrast to the power value of ∼0.43 that is found experimentally. We show from the numerical solution that this discrepancy is due to the momentum dissipation on the liquid interface.

  7. Analysis of Capillary Rise in Asymmetric Branch-Like Capillary (United States)

    Li, Caoxiong; Shen, Yinghao; Ge, Hongkui; Yang, Zhihui; Su, Shuai; Ren, Kai; Huang, Heyu


    Transport in porous media is common in nature, attracting many attentions for a long time. Tree-like network model is often used as a simplification for porous space, expressing the complexity of pore spaces instead of capillary bundle. To investigate spontaneous imbibition characteristics in this network, a dynamic asymmetric branch-like capillary model is used to represent basic network structure, using fractal method to represent tortuosity. This work investigates the influence of parameters on imbibition process in the branch-like capillary model. An analytical equation for the imbibition mass versus time is derived. Parameters from capillary structures to liquid properties are taken into account and analyzed based on the numerical solution of the equation. It is found that the imbibition process in asymmetric branch-like capillary model can be recognized by four sections and brunching tubes are positive for imbibition process. Concomitantly, meniscus arrest event is simulated and discussed. Moreover, the influence of parameters on imbibition process is discussed. These parameters can be classified as static and dynamic. Static parameters mainly change the capillary force, which are related to the ultimate imbibition mass or imbibition ability, while dynamic parameters mainly have influence on resistance of flowing fluid, which are related to the imbibition speed in the imbibition process.

  8. Modified monolithic silica capillary for preconcentration of catecholamines

    Institute of Scientific and Technical Information of China (English)


    Preconcentration of catecholamines by the modified monolithic silica in the capillary was investigated in this study. In order to achieve a microchip-based method for determining catecholamines in the saliva,the monolithic silica was fabricated in the capillary and the monolithic silica was chemically modified by on-column reaction with phenylboronate. Different modified methods were compared. The concentration conditions were optimized. This study indicates the applicability of the modified monolithic sili...


    Directory of Open Access Journals (Sweden)

    John F Bertram


    Full Text Available Focal and segmental glomerulosclerosis (FSGS is a chronic renal disorder characterized by segmental glomerular lesions and widespread podocyte foot process effacement. We have previously shown that glomerular enlargement (hypertrophy precedes the development of FSGS in an animal model not previously thought to involve glomerular hypertrophy. This hypertrophy involved growth of glomerular capillaries. The aim of the present study was to determine whether the capillary growth involved an increase in the number of capillaries per glomerulus, or lengthening of existing capillaries. In addition, we examined the contribution of glomerular cell hyperplasia to the hypertrophy. We found that glomerular capillary growth in this model appears to primarily involve lengthening of existing capillaries rather that sprouting of new capillaries, and that glomerular cell proliferation contributes to the glomerular hypertrophy.


    Directory of Open Access Journals (Sweden)

    Menderes LEVENT


    Full Text Available In this study, design and calibration of a capillary flowmeter set was represented. The capillary flowmeters will be used for measurements of small gas flows having laminar flow regime. The gases (such as, nitrogen, argon, methane, hydrogen and carbon-dioxide supplied from high pressure gas bottles and passed through capillary flowmeters (1 to 3 at various times. Each capillary flowmeter was made of glass and calibrated with one or two gases. Outlet of the capillary flowmeters were connected to the needle valves which have been used for regulating gas flowrates of the capillary flowmeters. Gases individually passed to a bubble flowmeter, and residence time of gases are recorded by using a stop watch. Then, from collected experimental results actual gas flowrates through the capillary flowmeters are calculated by using Hagen-Poiseuille equation.

  11. DNA typing by capillary electrophoresis

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, N.


    Capillary electrophoresis is becoming more and more important in nucleic acid analysis including DNA sequencing, typing and disease gene measurements. This work summarized the background of DNA typing. The recent development of capillary electrophoresis was also discussed. The second part of the thesis showed the principle of DNA typing based on using the allelic ladder as the absolute standard ladder in capillary electrophoresis system. Future work will be focused on demonstrating DNA typing on multiplex loci and examples of disease diagnosis in the on-line format of PCR-CE. Also capillary array electrophoresis system should allow high throughput, fast speed DNA typing. Only the introduction and conclusions for this report are available here. A reprint was removed for separate processing.

  12. Selectivity in capillary electrokinetic separations

    NARCIS (Netherlands)

    de Zeeuw, R.A; de Jong, G.J.; Ensing, K


    This review gives a survey of selectivity modes in capillary electrophoresis separations in pharmaceutical analysis and bioanalysis. Despite the high efficiencies of these separation techniques, good selectivity is required to allow quantitation or identification of a Chemistry and Toxicology, parti

  13. Development of new chiral ligand exchange capillary electrophoresis system with amino acid ionic liquids ligands and its application in studying the kinetics of L-amino acid oxidase

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Bingbing [Beijing National Laboratory for Molecular Sciences, Key Lab of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); College of Food Sciences and Engineering, Shandong Agricultural University, Tai’an, Shandong 271018 (China); Mu, Xiaoyu [Beijing National Laboratory for Molecular Sciences, Key Lab of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Qi, Li, E-mail: [Beijing National Laboratory for Molecular Sciences, Key Lab of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)


    Highlights: • Novel amino acid ionic liquids with pyridinium as cations and L-lysine as anion were synthesized. • These synthesized AAILs have been explored as the ligands coordinated with Zn(II) in CLE-CE system. • The developed CLE-CE method could be used for the enantioseparation of Dns-D, L-amino acids. • The kinetic contents of L-amino acid oxidase were investigated with the proposed CLE-CE system. - Abstract: New kinds of amino acid ionic liquids (AAILs) with pyridinium as cations and L-lysine (L-Lys) as anion have been developed as the available chiral ligands coordinated with Zn(II) in chiral ligand-exchange capillary electrophoresis (CLE-CE). Four kinds of AAILs, including [1-ethylpyridinium][L-lysine], 1-butylpyridinium][L-lysine], [1-hexylpyridinium][L-lysine] and 1-[octylpyridinium][L-lysine], were successfully synthesized and characterized by nuclear magnetic resonance and mass spectrometry. Compared with other AAILs, the best chiral separation of Dns-D, L-amino acids could be achieved when [1-ethylpyridinium][L-lysine] was chosen as the chiral ligand. It has been found that after investigating the influence of key factors on the separation efficiency, such as pH of buffer solution, the ratio of Zn(II) to ligand and complex concentration, eight pairs of Dns-D, L-AAs enantiomers could be baseline separated and three pairs were partly separated under the optimum conditions. The proposed CLE-CE method also exhibited favorable quantitative analysis property of Dns-D, L-Met with good linearity (r{sup 2} = 0.998) and favorable repeatability (RSD ≤ 1.5%). Furthermore, the CLE-CE system was applied in investigating the kinetic contents of L-amino acid oxidase, which implied that the proposed system has the potential in studying the enzymatic reaction mechanism.

  14. Transport of monocarboxylic acids at the blood-brain barrier: Studies with monolayers of primary cultured bovine brain capillary endothelial cells

    Energy Technology Data Exchange (ETDEWEB)

    Terasaki, T.; Takakuwa, S.; Moritani, S.; Tsuji, A. (Department of Pharmaceutics, Faculty of Pharmaceutical Sciences, Kanazawa University (Japan))


    The kinetics and mechanism of the transport of monocarboxylic acids (MCAs) were studied by using primary cultured bovine brain capillary endothelial cells. Concentration-dependent uptake of acetic acid was observed, and the kinetic parameters were estimated as follows: the Michaelis constant, Kt, was 3.41 {plus minus} 1.87 mM, the maximum uptake rate, Jmax, was 144.7 {plus minus} 55.7 nmol/mg of protein/min and the nonsaturable first-order rate constant, Kd, was 6.66 {plus minus} 1.98 microliters/mg of protein/min. At medium pH below 7.0, the uptake rate of (3H)acetic acid increased markedly with decreasing medium pH, whereas pH-independent uptake was observed in the presence of 10 mM acetic acid. An energy requirement for (3H)acetic acid uptake was also demonstrated, because metabolic inhibitors (2,4-dinitrophenol and rotenone) reduced significantly the uptake rate (P less than .05). Carbonylcyanide-p-trifluoro-methoxyphenylhydrazone, a protonophore, inhibited significantly the uptake of (3H)acetic acid at medium pH of 5.0 and 6.0, whereas 4,4{prime}-diisothiocyanostilben-2,2{prime}-disulfonic acid did not. Several MCAs inhibited significantly the uptake rate of (3H)acetic acid, whereas di- and tricarboxylic acids did not. The uptake of (3H)acetic acid was competitively inhibited by salicylic acid, with an inhibition constant, Ki, of 3.60 mM, suggesting a common transport system between acetic acid and salicylic acid. Moreover, at the medium pH of 7.4, salicylic acid and valproic acid inhibited significantly the uptake of (3H)acetic acid, demonstrating that the transport of MCA drugs could also be ascribed to the MCA transport system at the physiologic pH.

  15. Estimation of the number of alveolar capillaries by the Euler number (Euler-Poincaré characteristic). (United States)

    Willführ, Alper; Brandenberger, Christina; Piatkowski, Tanja; Grothausmann, Roman; Nyengaard, Jens Randel; Ochs, Matthias; Mühlfeld, Christian


    The lung parenchyma provides a maximal surface area of blood-containing capillaries that are in close contact with a large surface area of the air-containing alveoli. Volume and surface area of capillaries are the classic stereological parameters to characterize the alveolar capillary network (ACN) and have provided essential structure-function information of the lung. When loss (rarefaction) or gain (angiogenesis) of capillaries occurs, these parameters may not be sufficient to provide mechanistic insight. Therefore, it would be desirable to estimate the number of capillaries, as it contains more distinct and mechanistically oriented information. Here, we present a new stereological method to estimate the number of capillary loops in the ACN. One advantage of this method is that it is independent of the shape, size, or distribution of the capillaries. We used consecutive, 1 μm-thick sections from epoxy resin-embedded material as a physical disector. The Euler-Poincaré characteristic of capillary networks can be estimated by counting the easily recognizable topological constellations of "islands," "bridges," and "holes." The total number of capillary loops in the ACN can then be calculated from the Euler-Poincaré characteristic. With the use of the established estimator of alveolar number, it is possible to obtain the mean number of capillary loops per alveolus. In conclusion, estimation of alveolar capillaries by design-based stereology is an efficient and unbiased method to characterize the ACN and may be particularly useful for studies on emphysema, pulmonary hypertension, or lung development.

  16. Clinical application of a rapid microbiological test based on capillary zone electrophoresis to assess local skin infection

    Directory of Open Access Journals (Sweden)

    Szeliga Jacek


    Full Text Available Abstract Background The basic clinical problem associated with infection treatment is the fact that classic, commonly and routinely used isolation and identification methods are based on long-term processes of a phenotypic analysis of microorganisms. Consequently sometimes, especially in small centres, rapid implementation of antibacterial treatment becomes delayed. The work presents the initial results of rapid microbiological identification based on an original method of capillary zone electrophoresis (CZE. The study involved the analysis of 78 biological samples from post-operative wounds and trophic ulcers. Results The attempt was made to identify individual bacterial species based on characteristic features of electropherograms achieved. Finally, G(+ cocci type bacteria and different G(- rods were identified with sensitivity of 88.1% and specificity of 100%. Conclusions Based on the clinical trials using an electrophoretic technique in the field of microbiological diagnostics of infected exudate from a post-operative wound it can be concluded that it is a rapid and relatively sensitive method for initial identification of infectious pathogens.


    Directory of Open Access Journals (Sweden)

    Marián Valko


    Full Text Available The free radical generation is related to the oxidation process in biological systems as well as in foods. It was found that oxidation is affected by antioxidants that can act as radical scavengers. Objective of the present work was to study the free radical scavenging capacity of opium poppy (Papaver somniferum L. extract by using the DPPH test and to verify the suitability of the micellar electrokinetic capillary chromatography (MEKC technique for analytical assessment and determination of three major poppy alkaloids (thebaine, morphine and papaverine. Because of its generally high separation efficiency, the MEKC is successfully used for analytical evaluation of biologically active substances usually without special claims for sample preparation. The results of DPPH test have shown that poppy contains components capable of terminating free radicals. We have confirmed that nature of the solvent used for the electrophoretic medium in MEKC has a strong influence on the separation efficiency. In our experiments, the most effective solvent was mixture of water to acetonitrile (ratio 4:6.

  18. Application of capillary gas chromatography to the study of hydrolysis of the nerve agent VX in rat plasma. (United States)

    Bonierbale, E; Debordes, L; Coppet, L


    We present here a gas chromatography technique allowing the detection and quantification of VX [O-ethyl S-(2-diisopropylaminoethyl)methylphosphonothiolate] as well as its P-S bond hydrolysis product diisopropylaminoethanethiol directly from spiked rat plasma. This technique was applied to study VX hydrolysis in rat plasma. We observed that 53 +/- 4% of 374 microM VX disappeared from spiked plasma after 2 h. VX disappearance was mainly related to enzymatic cleavage of the P-S bond (Km = 2.5 mM and Vmax = 13.3 nmol min-1 ml-1 of rat plasma). The activity was totally inhibited by 1 mM Hg2+ and was also inhibited by metal chelators.

  19. Demonstrating Electrophoretic Separation in a Straight Paper Channel Delimited by a Hydrophobic Wax Barrier (United States)

    Xu, Chunxiu; Lin, Wanqi; Cai, Longfei


    A demonstration is described of electrophoretic separation of carmine and sunset yellow with a paper-based device. The channel in the paper device was fabricated by hand with a wax pen. Electrophoretic separation of carmine and sunset yellow was achieved within a few minutes by applying potential on the channel using a simple and inexpensive power…

  20. Scleroderma pattern of nailfold capillary changes as predictive value for the development of a connective tissue disease: a follow-up study of 3,029 patients with primary Raynaud's phenomenon. (United States)

    Pavlov-Dolijanovic, Slavica; Damjanov, Nemanja S; Stojanovic, Roksanda M; Vujasinovic Stupar, Nada Z; Stanisavljevic, Dejana M


    To assess the prognostic value of scleroderma pattern of nailfold capillary changes for the development of connective tissue diseases (CTD) in subjects with primary Raynaud's phenomenon (RP). The study included 3,029 consecutive patients with primary RP who had been followed at 6-month intervals during the mean of 4.8 years. The pathological features of nailfold capillaroscopy were recorded in all patients who had neither clinical nor serological signs of a CTD. In patients who developed CTD, capillary changes obtained 6 months prior to diagnosis were analyzed. A possible relationship between capillary changes and the presence of associated CTD was assessed. At the end of follow-up, 1,660 (54,8%) patients have still the primary RP, 246 (8,1%) had suspected secondary RP, and 1,123 (37,1%) patients developed CTD (363 undifferentiated CTD, 263 systemic sclerosis, 143 systemic lupus erythematosus, 106 rheumatoid arthritis, 102 Sjögren's syndrome, 61 overlap syndrome, 30 vasculitides, 24 mixed CTD, 19 polymyositis, 7 dermatomyositis, and 5 primary antiphospholipid syndrome). Scleroderma pattern were significantly associated with the development of systemic sclerosis [P = .00001, sensitivity 94%, specificity 92%, positive predictive value 52%, negative predictive value 99%, and odds ratio 163 (95% CI, 97,9-271,5)], as well as dermatomyositis (P = .0004), overlap syndrome with signs of systemic sclerosis (P = .0001), and mixed connective tissue disease (P = .007). Capillary microscopy is effective method for differentiation between primary and secondary RP and useful tool for the prediction of scleroderma spectrum disorders in RP patients.

  1. Capillary Electrophoretic Analysis of Common Illicit Drugs%常见毒品的毛细管电泳分析

    Institute of Scientific and Technical Information of China (English)

    孟品佳; 孙毓庆; 姜兆林; 姚丽娟; 王景翰


    系统地研究了毛细管电泳分析中各种因素对常见毒品混合物分析的影响,用均匀设计确定了适用几类毒品分离分析的最佳电泳条件. 并采用固相提取技术、毛细管区带电泳检测方法对血和尿生物检材中的冰毒、吗啡、单乙酰吗啡、可待因、海洛因等毒品进行了测定. 通过对各种提取剂回收率的测定, 认为GDX301和反相C18提取效果较好; 并考察了几种毒品的线性关系、最小检测量等, 为体内毒品分析提供了一些可借鉴的数据.

  2. A study on relative populations and gain coefficients of neon-like krypton for fast moving plasma in capillary discharges

    Energy Technology Data Exchange (ETDEWEB)

    Masnavi, M.; Kikuchi, T.; Nakajima, M.; Horioka, K. [Tokyo Inst. of Technology, Dept. of Energy Sciences, Yokohama, Kanagawa (Japan)


    X-ray laser gains and the level populations for collisionally pumped neon (Ne)-like Krypton (KrXXVII) ions have been studied considering the 27 - levels of the 2s{sup 2}2p{sup 6}, 2s{sup 2}2p{sup 5}3s, 2s{sup 2}2p{sup 5}3p and 2s{sup 2}2p{sup 5}3d configurations. It was found that large gains on the 3p {sup 1}S{sub 0} {yields} 3s {sup 3}P{sub 1}, 3p {sup 3}D{sub 2} {yields} 3s {sup 3}P{sub 1}, and 3p {sup 3}S{sub 1} {yields} 3s {sup 1}P{sub 1} transitions are formed for the electron density between 10{sup 20} and 10{sup 22} cm{sup -3} at the electron temperatures 0.9,1 and 3 keV. The effect of the opacity of the 3d{sup 1}P{sub 1} - 2p{sup 61}S{sub 0}, 3d{sup 3}D{sub 1} - 2p{sup 61}S{sub 0}, 3d{sup 3}P{sub 1} - 2p{sup 61}S{sub 0}, 3s{sup 3}P{sub 1} - 2p{sup 61}S{sub 0} and 3s{sup 1}P{sub 1} - 2p{sup 61}S{sub 0} transitions are performed using the escape probability factor approximation, for both the static and dynamic plasmas, which include the effect of the large velocity gradient. In addition, we found some theoretical line-intensity ratios that are sensitive on the electron density, the electron temperature, and also opacity in the interest regime of Ne-like Krypton x-ray laser. (author)

  3. Automated dual capillary electrophoresis system with hydrodynamic injection for the concurrent determination of cations and anions

    Energy Technology Data Exchange (ETDEWEB)

    Pham, Thi Thanh Thuy; Mai, Thanh Duc [University of Basel, Department of Chemistry, Spitalstrasse 51, Basel 4056 (Switzerland); Centre for Environmental Technology and Sustainable Development (CETASD), Hanoi University of Science, Nguyen Trai Street 334, Hanoi (Viet Nam); Nguyen, Thanh Dam [Centre for Environmental Technology and Sustainable Development (CETASD), Hanoi University of Science, Nguyen Trai Street 334, Hanoi (Viet Nam); Sáiz, Jorge [Department of Analytical Chemistry, Physical Chemistry and Chemical Engineering – University of Alcalá, Ctra. Madrid-Barcelona km 33.6, Alcalá de Henares, Madrid 28871 (Spain); Pham, Hung Viet, E-mail: [Centre for Environmental Technology and Sustainable Development (CETASD), Hanoi University of Science, Nguyen Trai Street 334, Hanoi (Viet Nam); Hauser, Peter C., E-mail: [University of Basel, Department of Chemistry, Spitalstrasse 51, Basel 4056 (Switzerland)


    Highlights: • Concurrent determination of cations and anions was carried out by electrophoretic separation. • Optimized conditions for each class of analystes was possible by using separate capillaries. • Simultaneous hydrodynamic injection was carried out. • Pneumatic actuation was used for flushing and sample handling. • The denitrification of drinking water was successfully demonstrated. - Abstract: The capillary electrophoresis instrument developed for the concurrent determination of cations and anions features two separate capillaries and individual detectors to allow independent optimization for each group of ions. The capillaries are joined in a common injector block. The sample is drawn into the injector with a small membrane pump and automated simultaneous injection into both capillaries is achieved by pressurization of the fluid with compressed air. Flushing of the injector and of the capillaries with the background electrolyte is also carried out automatically by the same means. The buffer consisted of 12 mM histidine and 2 mM 18-crown-6 adjusted to pH 4 with acetic acid and was suitable for the contactless conductivity detection employed. The system was optimized for the determination of cationic NH{sub 4}{sup +} and anionic NO{sub 3}{sup −} and NO{sub 2}{sup −}, and linear calibration curves from about 20 μM up to about 1.5 mM were obtained for these ions. In a test run over 8 h, the reproducibility for the peak areas was within ±7%. For demonstration, the instrument was successfully applied to the concurrent monitoring of the concentrations of the three ions during the biological removal of ammonium from contaminated groundwater in a sequencing batch reactor, where NO{sub 3}{sup −} and NO{sub 2}{sup −} are formed as intermediate products.

  4. Capillary condensation for fluids in spherical cavities


    Urrutia, Ignacio; Szybisz, Leszek


    The capillary condensation for fluids into spherical nano-cavities is analyzed within the frame of two theoretical approaches. One description is based on a widely used simplified version of the droplet model formulated for studying atomic nuclei. The other, is a more elaborated calculation performed by applying a density functional theory. The agreement between both models is examined and it is shown that a small correction to the simple fluid model improves the predictions. A connection to ...

  5. Functionalization and characterization of persistent luminescence nanoparticles by dynamic light scattering, laser Doppler and capillary electrophoresis. (United States)

    Ramírez-García, Gonzalo; d'Orlyé, Fanny; Gutiérrez-Granados, Silvia; Martínez-Alfaro, Minerva; Mignet, Nathalie; Richard, Cyrille; Varenne, Anne


    Zinc gallate nanoparticles doped with chromium (III) (ZnGa1.995O4:Cr0.005) are innovative persistent luminescence materials with particular optical properties allowing their use for in vivo imaging. They can be excited in the tissue transparency window by visible photons and emit light for hours after the end of the excitation. This allows to observe the probe without any time constraints and without autofluorescence signals produced by biological tissues. Modification of the surface of these nanoparticles is essential to be colloidally stable not only for cell targeting applications but also for proper distribution in living organisms. The use of different methods for controlling and characterizing the functionalization process is imperative to better understand the subsequent interactions with biological elements. This work explores for the first time the characterization and optimization of a classic functionalization sequence, starting with hydroxyl groups (ZGO-OH) at the nanoparticle surface, followed by an aminosilane-functionalization intermediate stage (ZGO-NH2) before PEGylation (ZGO-PEG). Dynamic light scattering and laser doppler electrophoresis were used in combination with capillary electrophoresis to characterize the nanoparticle functionalization processes and control their colloidal and chemical stability. The hydrodynamic diameter, zeta potential, electrophoretic mobility, stability over time and aggregation state of persistent luminescence nanoparticles under physiological-based solution conditions have been studied for each functional state. Additionally, a new protocol to improve ZGO-NH2 stability based on a thermal treatment to complete covalent binding of (3-aminopropyl) triethoxysilane onto the particle surface has been optimized. This thorough control increases our knowledge on these nanoparticles for subsequent toxicological studies and ultimately medical application.

  6. Electrophoretic Capture of a DNA Chain into a Nanopore

    CERN Document Server

    Rowghanian, Payam


    Based on our formulation of the DNA electrophoresis near a pore [P. Rowghanian and A. Y. Grosberg, Phys. Rev. E 87, 042723 (2013)], we address the electrophoretic DNA capture into a nanopore as a steady-state process of particle absorption to a sink placed on top of an energy barrier. Reproducing the previously observed diffusion-limited and barrier-limited regimes as two different limits of the particle absorption process and matching the data, our model suggests a slower growth of the capture rate with the DNA length for very large DNA molecules than the previous model, motivating more experiments beyond the current range of electric field and DNA length. At moderately weak electric fields, our model predicts a different effect, stating that the DNA length dependence of the capture rate first disappears as the field is reduced and eventually reverses to a decreasing trend with $N$.

  7. Coating of calcium phosphate on biometallic materials by electrophoretic deposition

    Institute of Scientific and Technical Information of China (English)

    ZHANG Er-lin; YANG Ke


    Although biometallic materials have been used as bone implant materials for a long time, they are still detected as foreign bodies by human immune system. Calcium phosphate coating, especially hydroxyapatite(HA)coating attracts special attention due to its good biocompatibility. Being one of the effective methods used to deposit HA coating onto the metallic implant, the electrophoretic deposition(EPD) was reviewed in detail, including the process of EPD, the advantages and disadvantages, the important processing factors and the microstructure and mechanical properties of the coating. Research results on the processing and the coating show potential application of EPD process to the biomedical materials surface modification. In addition, the nanoparticulate HA coating as a new trend in HA coating was also introduced.

  8. A simplified electrophoretic system for determining molecular weights of proteins. (United States)

    Manwell, C


    Electrophoresis of 31 different proteins in commercially prepared polyacrylamide gradient gels, Gradipore, yields a linear relationship between a hypothetical limiting pore size (the reciprocal of a limiting gel concentration, GL) and the cube root of the mol.wt., over the range 13 500-9000 000. A regression analysis of these data reveals that 98.6% of all variability in 1/GL is explained by the molecular weight, and this degree of accuracy compares favourably with existing methods for the determination of molecular weight by retardation of mobility in polyacrylamide. This new procedure has the additional advantages that molecular-weight standards can be obtained from readily available body fluids or tissue extracts by localizing enzymes and other proteins by standard histochemical methods, and that the same electrophoretic system can be used in determining molecular weights as is used in routine surveys of populations for individual and species variation in protein heterogeneity.

  9. Improved Refrigerant Characteristics Flow Predictions in Adiabatic Capillary Tube

    Directory of Open Access Journals (Sweden)

    Shodiya Sulaimon


    Full Text Available This study presents improved refrigerant characteristics flow predictions using homogenous flow model in adiabatic capillary tube, used in small vapor compression refrigeration system. The model is based on fundamental equations of mass, momentum and energy. In order to improve the flow predictions, the inception of vaporization in the capillary tube is determined by evaluating initial vapor quality using enthalpy equation of refrigerant at saturation point and the inlet entrance effect of the capillary tube is also accounted for. Comparing this model with experimental data from open literature showed a reasonable agreement. Further comparison of this new model with earlier model of Bansal showed that the present model could be use to improve the performance predictions of refrigerant flow in adiabatic capillary tube.

  10. Signal amelioration of electrophoretically deposited whole-cell biosensors using external electric fields

    Energy Technology Data Exchange (ETDEWEB)

    Ben-Yoav, Hadar, E-mail: [Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel-Aviv 69978 (Israel); Amzel, Tal [Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel-Aviv 69978 (Israel); Sternheim, Marek [Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel-Aviv, 69978 (Israel); Belkin, Shimshon [Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem, 91904 (Israel); Rubin, Adi [Department of Molecular Microbiology and Biotechnology, Faculty of Life Sciences, Tel Aviv University, Tel-Aviv, 69978 (Israel); Shacham-Diamand, Yosi [Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel-Aviv 69978 (Israel); Freeman, Amihay [Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel-Aviv, 69978 (Israel)


    Highlights: > We present an electrochemical whole-cell biochip that can apply electric fields. > We examine the integration of cells on a biochip using electrophoretic deposition. > The effect of electric fields on the whole-cell biosensor has been demonstrated. > Relatively short DC electric pulse improves the performance of whole-cell biosensors. > Prolonged AC electric fields deteriorated the whole-cell biosensor performance. - Abstract: This paper presents an integrated whole-cell biochip system where functioning cells are deposited on the solid micro-machined surfaces while specially designed indium tin oxide electrodes that can be used to apply controllable electric fields during various stages; for example during cell deposition. The electrodes can be used also for sensing currents associated with the sensing mechanisms of electrochemical whole-cell biosensors. In this work a new approach integrating live bacterial cells on a biochip using electrophoretic deposition is presented. The biomaterial deposition technique was characterized under various driving potentials and chamber configurations. An analytical model of the electrophoretic deposition kinetics was developed and presented here. The deposited biomass included genetically engineered bacterial cells that may respond to toxic material exposure by expressing proteins that react with specific analytes generating electrochemically active byproducts. In this study the effect of external electric fields on the whole-cell biochips has been successfully developed and tested. The research hypothesis was that by applying electric fields on bacterial whole-cells, their permeability to the penetration of external analytes can be increased. This effect was tested and the results are shown here. The effect of prolonged and short external electric fields on the bioelectrochemical signal generated by sessile bacterial whole-cells in response to the presence of toxins was studied. It was demonstrated that relatively

  11. Two-dimensional capillary electrophoresis using tangentially connected capillaries. (United States)

    Sahlin, Eskil


    A novel type of fused silica capillary system is described where channels with circular cross-sections are tangentially in contact with each other and connected through a small opening at the contact area. Since the channels are not crossing each other in the same plane, the capillaries can easily be filled with different solutions, i.e. different solutions will be in contact with each other at the contact point. The system has been used to perform different types of two-dimensional separations and the complete system is fully automated where a high voltage switch is used to control the location of the high voltage in the system. Using two model compounds it is demonstrated that a type of two-dimensional separation can be performed using capillary zone electrophoresis at two different pH values. It is also shown that a compound with acid/base properties can be concentrated using a dynamic pH junction mechanism when transferred from the first separation to the second separation. In addition, the system has been used to perform a comprehensive two-dimensional capillary electrophoresis separation of tryptic digest of bovine serum albumin using capillary zone electrophoresis followed by micellar electrokinetic chromatography.

  12. Theoretical study and practical application of the capillary film solar distiller; Etude theorique et application pratique du distillateur solaire a film capillaire

    Energy Technology Data Exchange (ETDEWEB)

    Bouchekima, B. [Institut de Chimie Industrielle, Universite de Blida (Algeria); Gros, B. [Universite Paul Sabatier, Dept. Genie Chimique, 31 - Toulouse (France); Ouahes, R. [Laboratoire de Chimie Solaire, USTHB, El Alia (Algeria); Diboun, M. [Institut de Chimie Industrielle, USTHB, El Alia (Algeria)


    This paper presents theoretical considerations and results of experiments carried out with a capillary film multiple effect distiller.It is made up of identical evaporation-condensation cells. The brine to be evaporated is a film impregnating a fabric assumed to be very this and adhering by capillarity forces to the wall of the plate. This justifies the device name: DIstillet with a FIlm in CAPillary motion, it was designed and patented by R. and C. Ouahes and P. Le Goff. Its advantage resides in the reuse of latent heat of stream condensed in the one stage, for water evaporation in the subsequent stage. The research and development of this desalination process is carried out under the following aspects: modeling of heat and mass transfer, experimentation under direct solar radiation in South Algeria and technical development with the aim to optimise the efficiency of the distiller. (authors)

  13. Effect of façade impregnation on feasibility of capillary active thermal internal insulation for a historic dormitory – A hygrothermal simulation study

    DEFF Research Database (Denmark)

    Finken, Gholam Reza; Bjarløv, Søren Peter; Peuhkuri, Ruut Hannele


    Internal insulation of external walls is known to create moisture performance challenges due to increased moisture levels and condensation risk on the cold side of the insulation. Capillary active/hydrophilic insulations have been introduced to solve these moisture problems, since they are able...... to transport liquid moisture to the inner surface and enable it to dry. Experience with this insulation type is rare in Denmark. In hygrothermal 1D computer simulations, several more or less capillary active insulation systems (AAC, calcium silicate, IQ-Therm) in various thicknesses (30–150 mm) have been...... tested for their hygrothermal performance. The original construction was a 228 mm solid brick masonry wall in a Copenhagen historic dormitory. All simulated systems showed critical relative humidity values above 80% and high risk of mould growth behind the insulation and some also on the interior surface...

  14. The geometry and wetting of capillary folding

    CERN Document Server

    Péraud, Jean-Philippe


    Capillary forces are involved in a variety of natural phenomena, ranging from droplet breakup to the physics of clouds. The forces from surface tension can also be exploited in industrial application provided the length scales involved are small enough. Recent experimental investigations showed how to take advantage of capillarity to fold planar structures into three-dimensional configurations by selectively melting polymeric hinges joining otherwise rigid shapes. In this paper we use theoretical calculations to quantify the role of geometry and fluid wetting on the final folded state. Considering folding in two and three dimensions, studying both hydrophilic and hydrophobic situations with possible contact angle hysteresis, and addressing the shapes to be folded to be successively infinite, finite, curved, kinked, elastic, we are able to derive an overview of the geometrical parameter space available for capillary folding.

  15. Novel cationic polyelectrolyte coatings for capillary electrophoresis. (United States)

    Duša, Filip; Witos, Joanna; Karjalainen, Erno; Viitala, Tapani; Tenhu, Heikki; Wiedmer, Susanne K


    The use of bare fused silica capillary in CE can sometimes be inconvenient due to undesirable effects including adsorption of sample or instability of the EOF. This can often be avoided by coating the inner surface of the capillary. In this work, we present and characterize two novel polyelectrolyte coatings (PECs) poly(2-(methacryloyloxy)ethyl trimethylammonium iodide) (PMOTAI) and poly(3-methyl-1-(4-vinylbenzyl)-imidazolium chloride) (PIL-1) for CE. The coated capillaries were studied using a series of aqueous buffers of varying pH, ionic strength, and composition. Our results show that the investigated polyelectrolytes are usable as semi-permanent (physically adsorbed) coatings with at least five runs stability before a short coating regeneration is necessary. Both PECs showed a considerably decreased stability at pH 11.0. The EOF was higher using Good's buffers than with sodium phosphate buffer at the same pH and ionic strength. The thickness of the PEC layers studied by quartz crystal microbalance was 0.83 and 0.52 nm for PMOTAI and PIL-1, respectively. The hydrophobicity of the PEC layers was determined by analysis of a homologous series of alkyl benzoates and expressed as the distribution constants. Our result demonstrates that both PECs had comparable hydrophobicity, which enabled separation of compounds with log Po/w > 2. The ability to separate cationic drugs was shown with β-blockers, compounds often misused in doping. Both coatings were also able to separate hydrolysis products of the ionic liquid 1,5-diazabicyclo[4.3.0]non-5-ene acetate at highly acidic conditions, where bare fused silica capillaries failed to accomplish the separation.

  16. Human placental alkaline phosphatase electrophoretic alleles: Quantitative studies (United States)

    Lucarelli, Paola; Scacchi, Renato; Corbo, Rosa Maria; Benincasa, Alberto; Palmarino, Ricciotti


    Human placental alkaline phosphatase (ALP) activity has been determined in specimens obtained from 562 Italian subjects. The mean activities of the three common homozygotes (Pl 2 = 4.70 ± 0.24, Pl 1 = 4.09 ± 0.08, and Pl 3 = 2.15 ± 0.71 μmol of p-nitrophenol produced) were significantly different. The differences among the various allelic forms account for 10% of the total quantitative variation of the human placental alkaline phosphatase. PMID:7072721

  17. Assessment of Carbon- and Metal-Based Nanoparticle DNA Damage with Microfluidic Electrophoretic Separation Technology. (United States)

    Schrand, Amanda M; Powell, Thomas; Robertson, Tiffany; Hussain, Saber M


    In this study, we examined the feasibility of extracting DNA from whole cell lysates exposed to nanoparticles using two different methodologies for evaluation of fragmentation with microfluidic electrophoretic separation. Human lung macrophages were exposed to five different carbon- and metal-based nanoparticles at two different time points (2 h, 24 h) and two different doses (5 µg/ml, 100 µg/ml). The primary difference in the banding patterns after 2 h of nanoparticle exposure is more DNA fragmentation at the higher NP concentration when examining cells exposed to nanoparticles of the same composition. However, higher doses of carbon and silver nanoparticles at both short and long dosing periods can contribute to erroneous or incomplete data with this technique. Also comparing DNA isolation methodologies, we recommend the centrifugation extraction technique, which provides more consistent banding patterns in the control samples compared to the spooling technique. Here we demonstrate that multi-walled carbon nanotubes, 15 nm silver nanoparticles and the positive control cadmium oxide cause similar DNA fragmentation at the short time point of 2 h with the centrifugation extraction technique. Therefore, the results of these studies contribute to elucidating the relationship between nanoparticle physicochemical properties and DNA fragmentation results while providing the pros and cons of altering the DNA isolation methodology. Overall, this technique provides a high throughput way to analyze subcellular alterations in DNA profiles of cells exposed to nanomaterials to aid in understanding the consequences of exposure and mechanistic effects. Future studies in microfluidic electrophoretic separation technologies should be investigated to determine the utility of protein or other assays applicable to cellular systems exposed to nanoparticles.

  18. Electrophoretic deposition of siderite thin layers: Influence of electrode potential and deposition time

    Energy Technology Data Exchange (ETDEWEB)

    Ithurbide, A., E-mail: aurelie.ithurbide@cea.f [CEA Saclay/DEN/DPC/SECR, Laboratoire de Mesures et Modelisation de la Migration des Radionucleides, 91191 Gif-sur-Yvette (France); Peulon, S., E-mail: sophie.peulon@univ-evry.f [CNRS-Universite d' Evry-CEA, Laboratoire Analyse et Modelisation pour la Biologie et l' Environnement, UMR 8587, Boulevard Francois Mitterrand, 91025 Evry (France); Miserque, F. [CEA Saclay/DEN/DPC/SCP, Laboratoire de Reactivite des Surfaces et des Interfaces, 91191 Gif-sur-Yvette (France); Beaucaire, C. [CEA Saclay/DEN/DPC/SECR, Laboratoire de Mesures et Modelisation de la Migration des Radionucleides, 91191 Gif-sur-Yvette (France); Chausse, A. [CNRS-Universite d' Evry-CEA, Laboratoire Analyse et Modelisation pour la Biologie et l' Environnement, UMR 8587, Boulevard Francois Mitterrand, 91025 Evry (France); Poinssot, Ch. [CNRS-Universite d' Evry-CEA, Laboratoire Analyse et Modelisation pour la Biologie et l' Environnement, UMR 8587, Boulevard Francois Mitterrand, 91025 Evry (France); CEA Marcoule Saclay/DEN, Departement RadioChimie et Procedes, BP 17171 30207 Bagnols-sur-Ceze (France)


    Siderite thin layers have been obtained by electrophoretic deposition on an inert substrate (gold). Scanning electron microscopy image exhibits a compact and homogeneous film composed of round grains which diameter is about 1-2 {mu}m. The influence of two parameters, namely the electrode potential and the deposition time, on its thickness and its microstructure was investigated. The thickness was shown to be slightly dependent of the electrode potential (1.2 {mu}m for - 0.70 V and 1.7 {mu}m for - 0.95 V after 17 h). The crystallite size, estimated by X-ray diffraction patterns, was about 5 nm, depending on both electrode potential and deposition time. Despite its high sensitivity to oxygen, X-ray photoelectron spectroscopy spectra prove that the siderite surface has been kept out from oxidation. These siderite thin layers could be used as modified electrodes for further interaction studies.

  19. Self-organization of In2S3 quantum dots into fractal nanostructures by electrophoretic deposition. (United States)

    Vigneashwari, B; Tyagi, A K; Dash, S; Shankar, P; Manna, I; Suthanthiraraj, S Austin


    This paper describes the assembly of In2S3 quantum dots by electrophoretic deposition (EPD) and their subsequent self-organization into fractal nanostructures over ITO substrates. The surface morphology and the organization of these dots into nanostructures were analyzed using SEM, HRSEM and AFM techniques. These analyses reveal the existence, under appropriate conditions, of very unique nanoscale structural motifs and scale invariance associated with the assembly. Formation of such a well correlated assembly, although seems to be electric field driven, appears to be dominated by self-organizing mechanism. Such self-organized nano-scale structures consisting of cavities are likely to have fascinating condensed phase transport properties. The paper reports microscopic study of such fractal assemblies using SEM, HTSEM and AFM.

  20. Characteristics of copper meshes coated with carbon nanotubes via electrophoretic deposition (United States)

    Kim, Bu-Jong; Park, Jong-Seol; Hwang, Young-Jin; Park, Jin-Seok


    This study demonstrates the characteristics of a hybrid-type transparent electrode for touch screen panels, which was fabricated by coating carbon nanotubes (CNTs) via electrophoretic deposition (EPD) on copper (Cu)-meshes. The surface morphologies, visible-range transmittance and reflectance, and chromatic properties, such as yellowness and redness, of the fabricated CNTs-coated Cu mesh electrodes were characterized as functions of their dimensions (line-to-line spacing, line width, and electrode thickness) and compared with those of the Cu-mesh electrodes without coating of CNTs. The experimental results showed that the coating of CNTs substantially reduced the reflectance of the Cu-mesh electrodes and also improved their chromatic properties with their transmittance and sheet resistance only slightly changed, subsequently indicating that the CNTs-coated Cu-mesh electrodes possessed desirable characteristics for touch screen panels.

  1. Time-resolved study of the extreme-ultraviolet emission and plasma dynamics of a sub-Joule, fast capillary discharge

    Energy Technology Data Exchange (ETDEWEB)

    Valenzuela, J. C., E-mail: [Instituto de Físca, Pontificia Universidad Católica de Chile, Santiago (Chile); Instituto de Física, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, Macul, Santiago (Chile); Wyndham, E. S.; Favre, M. [Instituto de Física, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, Macul, Santiago (Chile)


    In this work, we discuss experimental observations on the dynamics of a fast, low energy capillary discharge when operated in argon and its properties as an intense source of extreme-ultraviolet (EUV) radiation. The discharge pre-ionization and self-triggering were accomplished by the use of the hollow cathode effect. This allowed a compact size and low inductance discharge with multi-kA current level and a quarter-period of ∼10 ns at sub-Joule energy level. We used the novel moiré and schlieren diagnostics with a 12 ps laser to obtain the time evolution of the line electron density and to study the plasma dynamics. EUV spectroscopy and filtered diodes were also implemented to estimate the plasma temperature and density throughout the evolution of the discharge. EUV source size was measured by using a filtered slit-wire camera. We observed that EUV emission starts from a compressed plasma on axis during the second quarter-period of the current and continues until the fifth quarter-period. Ionization levels from Ar VII to X were observed. By comparing the EUV emission spectra with synthetic spectra, we found that at the onset of emission (∼7 ns), the plasma is well fitted by a single Maxwellian electron distribution function with T{sub e} ∼ 12 eV and n{sub e} ∼ 10{sup 17 }cm{sup −3}. Close to peak emission (∼13 ns), plasma temperature and density increase to ∼20 eV and n{sub e} ∼ 10{sup 18 }cm{sup −3}, respectively. However, in order to successfully match the experimental data, a two component electron distribution function was necessary. Later in time, a smaller fraction in the high energy component and higher temperature suggests homogenization of the plasma. The moiré and schlieren diagnostics showed multiple radial compression-waves merging on axis throughout the discharge; they are an important heating mechanism that leads to a period of severe turbulence at peak EUV emission. It was also observed that emission

  2. Time-resolved study of the extreme-ultraviolet emission and plasma dynamics of a sub-Joule, fast capillary discharge (United States)

    Valenzuela, J. C.; Wyndham, E. S.; Favre, M.


    In this work, we discuss experimental observations on the dynamics of a fast, low energy capillary discharge when operated in argon and its properties as an intense source of extreme-ultraviolet (EUV) radiation. The discharge pre-ionization and self-triggering were accomplished by the use of the hollow cathode effect. This allowed a compact size and low inductance discharge with multi-kA current level and a quarter-period of ˜10 ns at sub-Joule energy level. We used the novel moiré and schlieren diagnostics with a 12 ps laser to obtain the time evolution of the line electron density and to study the plasma dynamics. EUV spectroscopy and filtered diodes were also implemented to estimate the plasma temperature and density throughout the evolution of the discharge. EUV source size was measured by using a filtered slit-wire camera. We observed that EUV emission starts from a compressed plasma on axis during the second quarter-period of the current and continues until the fifth quarter-period. Ionization levels from Ar VII to X were observed. By comparing the EUV emission spectra with synthetic spectra, we found that at the onset of emission (˜7 ns), the plasma is well fitted by a single Maxwellian electron distribution function with Te ˜ 12 eV and ne ˜ 1017 cm-3. Close to peak emission (˜13 ns), plasma temperature and density increase to ˜20 eV and ne ˜ 1018 cm-3, respectively. However, in order to successfully match the experimental data, a two component electron distribution function was necessary. Later in time, a smaller fraction in the high energy component and higher temperature suggests homogenization of the plasma. The moiré and schlieren diagnostics showed multiple radial compression-waves merging on axis throughout the discharge; they are an important heating mechanism that leads to a period of severe turbulence at peak EUV emission. It was also observed that emission ceases when the axial maximum of the electron density collapses.

  3. Capillary condensation of short-chain molecules. (United States)

    Bryk, Paweł; Pizio, Orest; Sokolowski, Stefan


    A density-functional study of capillary condensation of fluids of short-chain molecules confined to slitlike pores is presented. The molecules are modeled as freely jointed tangent spherical segments with a hard core and with short-range attractive interaction between all the segments. We investigate how the critical parameters of capillary condensation of the fluid change when the pore width decreases and eventually becomes smaller than the nominal linear dimension of the single-chain molecule. We find that the dependence of critical parameters for a fluid of dimers and of tetramers on pore width is similar to that of the monomer fluid. On the other hand, for a fluid of chains consisting of a larger number of segments we observe an inversion effect. Namely, the critical temperature of capillary condensation decreases with increasing pore width for a certain interval of values of the pore width. This anomalous behavior is also influenced by the interaction between molecules and pore walls. We attribute this behavior to the effect of conformational changes of molecules upon confinement.

  4. Relating chromatographic retention and electrophoretic mobility to the ion distribution within electrosprayed droplets. (United States)

    Bökman, C Fredrik; Bylund, Dan; Markides, Karin E; Sjöberg, Per J R


    Ions that are observed in a mass spectrum obtained with electrospray mass spectrometry can be assumed to originate preferentially from ions that have a high distribution to the surface of the charged droplets. In this study, a relation between chromatographic retention and electrophoretic mobility to the ion distribution (derived from measured signal intensities in mass spectra and electrospray current) within electrosprayed droplets for a series of tetraalkylammonium ions, ranging from tetramethyl to tetrapentyl, is presented. Chromatographic retention in a reversed-phase system was taken as a measure of the analyte's surface activity, which was found to have a large influence on the ion distribution within electrosprayed droplets. In addition, different transport mechanisms such as electrophoretic migration and diffusion can influence the surface partitioning coefficient. The viscosity of the solvent system is affected by the methanol content and will influence both diffusion and ion mobility. However, as diffusion and ion mobility are proportional to each other, we have, in this study, chosen to focus on the ion mobility parameter. It was found that the influence of ion mobility relative to surface activity on the droplet surface partitioning of analyte ions decreases with increasing methanol content. This effect is most probably coupled to the decrease in droplet size caused by the decreased surface tension at increasing methanol content. The same observation was made upon increasing the ionic strength of the solvent system, which is also known to give rise to a decreased initial droplet size. The observed effect of ionic strength on the droplet surface partitioning of analyte ions could also be explained by the fact that at higher ionic strength, a larger number of ions are initially closer to the droplet surface and, thus, the contribution of ionic transport from the bulk liquid to the liquid/air surface interface (jet and droplet surface), attributable to


    Directory of Open Access Journals (Sweden)

    Erika Cvetko


    Full Text Available The effect of ageing on the capillary network in skeletal muscles has produced conflicting results in both, human and animals studies. Some of the inconsistencies are due to non-comparable and biased methods that were applied on thin transversal sections, especially in muscles with complicated morphological structures, such as in human masseter muscle. We present a new immunohistochemical method for staining capillaries and muscle fibres in 100 µm thick sections as well as novel approach to 3D visualization of capillaries and muscle fibres. Applying confocal microscopy and virtual 3D stereological grids, or tracing capillaries in virtual reality, length of capillaries within a muscle volume or length of capillaries adjacent to muscle fibre per fibre length, fibre surface or fibre volume were evaluated in masseter muscle of young and old subjects by an unbiased approach. Our findings show that anatomic capillarity is well maintained in masseter muscle in old subjects; however, vascular remodelling occurs with age, which could be a response to changed muscle function and age-related muscle fibre type transformations.

  6. Non-Aqueous Capillary Electrophoresis (United States)

    Szumski, Michał; Buszewski, Bogusław

    Non-aqueous capillary electrophoresis and capillary electrochromatography are special variants of these techniques. Here, organic solvents or their mixtures with or without dissolved electrolytes are used as separation buffer or mobile phase, respectively. The most important features of non-aqueous systems are: better solubility of more hydrophobic ionic substances (many natural products) than in water, much less current and Joule heating allows for using highly concentrated buffers and/or larger capillary internal diameters, polar interactions are enhanced in organic solvents which is often highly advantageous in chiral separation systems. This chapter presents most frequently used solvents, their properties, as well as shows pH* scale which is often used in non-aqueous systems.

  7. Capillary imbibition in parallel tubes (United States)

    McRae, Oliver; Ramakrishnan, T. S.; Bird, James


    In modeling porous media two distinct approaches can be employed; the sample can be examined holistically, using global variables such as porosity, or it can be treated as a network of capillaries connected in series to various intermediate reservoirs. In forced imbibition this series-based description is sufficient to characterize the flow, due to the presence of an externally maintained pressure difference. However, in spontaneous imbibition, flow is driven by an internal capillary pressure, making it unclear whether a series-based model is appropriate. In this talk, we show using numerical simulations the dynamics of spontaneous imbibition in concentrically arranged capillary tubes. This geometry allows both tubes access to a semi-infinite reservoir but with inlets in close enough proximity to allow for interference. We compare and contrast the results of our simulations with theory and previous experiments. Schlumberger-Doll Research.

  8. Capillary interactions in Pickering emulsions (United States)

    Guzowski, J.; Tasinkevych, M.; Dietrich, S.


    The effective capillary interaction potentials for small colloidal particles trapped at the surface of liquid droplets are calculated analytically. Pair potentials between capillary monopoles and dipoles, corresponding to particles floating on a droplet with a fixed center of mass and subjected to external forces and torques, respectively, exhibit a repulsion at large angular separations and an attraction at smaller separations, with the latter resembling the typical behavior for flat interfaces. This change of character is not observed for quadrupoles, corresponding to free particles on a mechanically isolated droplet. The analytical results are compared with the numerical minimization of the surface free energy of the droplet in the presence of spherical or ellipsoidal particles.

  9. Evaluation of The Interaction between Netropsin and Double Stranded DNA by Capillary Zone Electrophoresis

    Institute of Scientific and Technical Information of China (English)


    Capillary zone electrophoresis (CZE) was applied to study the interaction between netropsin and a 14mer double stranded DNA (dsDNA). The binding constant of this interaction calculated from Scatchard plot was (1.07±0.10)×105 (mol/L)-1. The binding stoichiometry was 1:1. The use of polyacrylamide coated capillary showed better effect in the analysis of DNA than noncoated capillary.

  10. Capillary Rise in Macro and Micro Pores of Jersey Knitting Structure


    Sofien Benltoufa, Ph.D.; Faten Fayala, Ph.D.; Sassi BenNasrallah, Ph.D.


    Wicking in textile materials is a very complicated, multi-faceted phenomena. This paper investigated capillary rise in a jersey knitting structure. A mathematical model was developed based on the industrial construction parameters and the capillary mechanism. The capillary is studied in two pore's scales: macro and micro. In order to validate our model, a series of experiments was conducted on cotton jersey knitting varying the construction parameters. The results showed reasonably good corre...

  11. Measurements of an ion beam diameter extracted into air through a glass capillary

    Energy Technology Data Exchange (ETDEWEB)

    Fujita, Natsuko, E-mail: [Graduate School of Humanities and Sciences, Nara Women’s University, Nara, 630 8506 (Japan); Yamaki, Atsuko [Graduate School of Humanities and Sciences, Nara Women’s University, Nara, 630 8506 (Japan); Ishii, Kunikazu; Ogawa, Hidemi [Department of Physics, Nara Women’s University, Nara, 630 8506 (Japan)


    To establish techniques for in-air materials analysis using a glass capillary, we studied the beam distribution extracted in air as a function of the distance between the exit of the capillary and the target. We measured three-dimensional intensity distributions of the extracted beams, and compared the observed results with the model calculation. The comparison showed that the glass capillary technique is designed to reduce a divergence of the beam extracted into the air by a beam-focusing effect.

  12. Application of design of experiment on electrophoretic deposition of glass-ceramic coating materials from an aqueous bath

    Indian Academy of Sciences (India)

    Someswar Datta


    A process for application of abrasion- or corrosion-resistant glass-ceramic coating materials on metal substrate by electrophoretic deposition technique in an aqueous medium has been described. The effects of various process parameters, e.g. coating material concentration, time of deposition, applied current, pH of the suspension and concentration of the polymeric dispersant on the deposition efficiency have been studied. The process has been studied using a 23-factorial design technique of three independent variables; i.e. coating material concentration, applied current, and the time taken to achieve the best combination. The regression equation obtained explains the experimental results satisfactorily.

  13. AC electrophoretic deposition of organic-inorganic composite coatings. (United States)

    Yoshioka, T; Chávez-Valdez, A; Roether, J A; Schubert, D W; Boccaccini, A R


    Alternating current electrophoretic deposition (AC-EPD) of polyacrylic acid (PAA)-titanium oxide (TiO(2)) nanoparticle composites on stainless steel electrodes was investigated in basic aqueous solution. AC square wave with duty cycle of 80% was applied at a frequency of 1 kHz. FTIR-ATR spectra showed that both AC and direct current (DC) EPD successfully deposited PAA-TiO(2) composites. The deposition rate using AC-EPD was lower than that obtained in direct current DC-EPD. However, the microstructure and surface morphology of the deposited composite coatings were different depending on the type of electric field applied. AC-EPD applied for not more than 5 min led to smooth films without bubble formation, while DC-EPD for 1 min or more showed deposits with microstructural defects possibly as result of water electrolysis. AC-EPD was thus for the first time demonstrated to be a suitable technique to deposit organic-inorganic composite coatings from aqueous suspensions, showing that applying a square wave and frequency of 1 kHz leads to uniform PAA-TiO(2) composite coatings on conductive materials.

  14. Integrated Microfluidic Isolation of Aptamers Using Electrophoretic Oligonucleotide Manipulation (United States)

    Kim, Jinho; Olsen, Timothy R.; Zhu, Jing; Hilton, John P.; Yang, Kyung-Ae; Pei, Renjun; Stojanovic, Milan N.; Lin, Qiao


    We present a microfluidic approach to integrated isolation of DNA aptamers via systematic evolution of ligands by exponential enrichment (SELEX). The approach employs a microbead-based protocol for the processes of affinity selection and amplification of target-binding oligonucleotides, and an electrophoretic DNA manipulation scheme for the coupling of these processes, which are required to occur in different buffers. This achieves the full microfluidic integration of SELEX, thereby enabling highly efficient isolation of aptamers in drastically reduced times and with minimized consumption of biological material. The approach as such also offers broad target applicability by allowing selection of aptamers with respect to targets that are either surface-immobilized or solution-borne, potentially allowing aptamers to be developed as readily available affinity reagents for a wide range of targets. We demonstrate the utility of this approach on two different procedures, respectively for isolating aptamers against a surface-immobilized protein (immunoglobulin E) and a solution-phase small molecule (bisboronic acid in the presence of glucose). In both cases aptamer candidates were isolated in three rounds of SELEX within a total process time of approximately 10 hours.

  15. Origami paper-based fluidic batteries for portable electrophoretic devices. (United States)

    Chen, Sung-Sheng; Hu, Chih-Wei; Yu, I-Fan; Liao, Ying-Chih; Yang, Jing-Tang


    A manufacturing approach for paper-based fluidic batteries was developed based on the origami principle (three-dimension paper folding). Microfluidic channels were first created on a filter paper by a wax-printing method. Copper and aluminium sheets were then glued onto the paper as electrodes for the redox reaction. After the addition of copper sulphate and aluminium chloride, commonly available cellophane paper was attached as a membrane to separate the two electrodes. The resulting planar paper sheets were then folded into three-dimensional structures and compiled as a single battery with glue. The two half reactions (Al/Al(3+) and Cu/Cu(2+)) in the folded batteries provided an open-circuit potential from 0.82 V (one cell) to 5.0 V (eight cells in series) depending on the origami design. The prepared battery can provide a stable current of 500 μA and can light a regular LED for more than 65 min. These paper-based fluidic batteries in a set can also be compiled into a portable power bank to provide electric power for many electric or biomedical applications, such as LED lights and electrophoretic devices, as we report here.

  16. Alumina/Ce-Tzp Functionally Graded Materials by Electrophoretic Deposition

    Institute of Scientific and Technical Information of China (English)

    C.Zhao, J.Vleugels; O.Van Der Biest


    Cylindrical Al2O3/Ce-TZP functionally graded composites were fabricated by electrophoretic deposition and pressureless sintering in air. A continuous change in composition was realized by changing the composition of the suspension during deposition. In order to achieve full densification, a temperature above 1550℃ was necessary. The resultant FGM cylinder with a diameter of 5.6 mm shows the following structure: a central hole with a diameter less than 0.5 mm, a tough Ce-ZrO2 core with a diameter of about 3 mm, a gradient layer of about 1 mm, and a hard Al2O3-rich surface layer. The Ce-ZrO2 core has a Vickers hardness between 10and 11 GPa and an excellent toughness (>10 MPa√m). In the gradient layer, hardness and toughness vary continuously along the radius. The surface layer has a hardness of 15.5 GPa and a modest toughness of 2.5MPa√m.

  17. Fabrication of Electrophoretic Display Driven by Membrane Switch Array (United States)

    Senda, Kazuo; Usui, Hiroaki


    Electrophoretic devices (EPDs) and organic light-emitting diodes (OLEDs) have potential application in a large-area flexible displays, such as digital signage. For this purpose, a new backplane is capable of driving a large unit is required instead of thin-film transistors. In this paper we describe the fabrication of a membrane switch array suitable for driving large-scale flat-panel displays. An array of membrane switches was prepared using flexible printed circuit (FPC) technology of polyimide films, by combining low-temperature processes of lamination and copper electroplating methods. An array of 256 matrix switches with a pixel size of 7 mm2 was prepared to drive the EPD front panel. The switches were driven at a voltage of about 40 V and a frequency of 10 Hz. The operation characteristics agreed well with the result of the theoretical calculation. The calculation also suggested that driving voltage can be lowered by increasing pixel size. The contact resistance of the membrane switch was as low as 0.2 Ω, which implies the wide applicability of this device for driving a variety of elements.

  18. Solubilization and electrophoretic characterization of select edible nut seed proteins. (United States)

    Sathe, Shridhar K; Venkatachalam, Mahesh; Sharma, Girdhari M; Kshirsagar, Harshal H; Teuber, Suzanne S; Roux, Kenneth H


    The solubility of almond, Brazil nut, cashew nut, hazelnut, macadamia, pecan, pine nut, pistachio, walnut, and peanut proteins in several aqueous solvents was qualitatively and quantitatively assessed. In addition, the effects of extraction time and ionic strength on protein solubility were also investigated. Electrophoresis and protein determination (Lowry, Bradford, and micro-Kjeldahl) methods were used for qualitative and quantitative assessment of proteins, respectively. Depending on the seed, buffer type and ionic strength significantly affected protein solubility. The results suggest that buffered sodium borate (BSB; 0.1 M H(3)BO(3), 0.025 M Na(2)B(4)O(7), 0.075 M NaCl, pH 8.45) optimally solubilizes nut seed proteins. Qualitative differences in seed protein electrophoretic profiles were revealed. For a specific seed type, these differences were dependent on the solvent(s) used to solubilize the seed proteins. SDS-PAGE results suggest the polypeptide molecular mass range for the tree nut seed proteins to be 3-100 kDa. The results of native IEF suggested that the proteins were mainly acidic, with a pI range from >4.5 to <7.0. Western immunoblotting experiments indicated that rabbit polyclonal antibodies recognized substantially the same polypeptides as those recognized by the corresponding pooled patient sera IgE.

  19. Electrophoretic mobility patterns of collagen following laser welding (United States)

    Bass, Lawrence S.; Moazami, Nader; Pocsidio, Joanne O.; Oz, Mehmet C.; LoGerfo, Paul; Treat, Michael R.


    Clinical application of laser vascular anastomosis in inhibited by a lack of understanding of its mechanism. Whether tissue fusion results from covalent or non-covalent bonding of collagen and other structural proteins is unknown. We compared electrophoretic mobility of collagen in laser treated and untreated specimens of rat tail tendon (>90% type I collagen) and rabbit aorta. Welding was performed, using tissue shrinkage as the clinical endpoint, using the 808 nm diode laser (power density 14 watts/cm2) and topical indocyanine green dye (max absorption 805 nm). Collagen was extracted with 8 M urea (denaturing), 0.5 M acetic acid (non-denaturing) and acetic acid/pepsin (cleaves non- helical protein). Mobility patterns on gel electrophoresis (SDS-PAGE) after urea or acetic acid extraction were identical in the lasered and control tendon and vessel (confirmed by optical densitometry), revealing no evidence of formation of novel covalent bonds. Alpha and beta band intensity was diminished in pepsin incubated lasered specimens compared with controls (optical density ratio 0.00 +/- 9 tendon, 0.65 +/- 0.12 aorta), indicating the presence of denatured collagen. With the laser parameters used, collagen is denatured without formation of covalent bonds, suggesting that non-covalent interaction between denatured collagen molecules may be responsible for the weld. Based on this mechanism, welding parameters can be chosen which produce collagen denaturation without cell death.

  20. Electrophoretic High Molecular Weight DNA Purification Enables Optical Mapping (United States)

    Maydan, Jason; Thomas, Matthew; Tabanfar, Leyla; Mai, Laura; Poon, Hau-Ling; Pe, Joel; Hahn, Kristen; Goji, Noriko; Amoako, Kingsley; Marziali, Andre; Hanson, Dan


    Optical mapping generates an ordered restriction map from single, long DNA molecules. By overlapping restriction maps from multiple molecules, a physical map of entire chromosomes and genomes is constructed, greatly facilitating genome assembly in next generation sequencing projects, comparative genomics and strain typing. However, optical mapping relies on a method of preparing high quality DNA >250 kb in length, which can be challenging from some organisms and sample types. Here we demonstrate the ability of Boreal Genomics' Aurora instrument to provide pure, high molecular weight (HMW) DNA 250-1,100 kb in length, ideally suited for optical mapping. The Aurora performs electrophoretic DNA purification within an agarose gel in reusable cartridges, protecting long DNA molecules from shearing forces associated with liquid handling steps common to other purification methods. DNA can be purified directly from intact cells embedded and lysed within an agarose gel, preserving the highest molecular weight DNA possible while achieving exceptional levels of purity. The Aurora delivers DNA in a buffer solution, where DNA can be condensed and protected from shearing during recovery with a pipette. DNA is then returned to its regular coiled state by simple dilution prior to optical mapping. Here we present images showing HMW DNA purification taking place in the Aurora and subsequent images of single DNA molecules on OpGen's Argus® Optical Mapping System. Future work will focus on further optimizing Aurora HMW DNA purification to bias DNA recovery in favor of only the longest molecules in a sample, maximizing the benefits of optical mapping.

  1. Optimization strategies for separation of sulfadiazines using Box-Behnken design by liquid chromatography and capillary electrophoresis

    Institute of Scientific and Technical Information of China (English)

    GONG Wen-jun; ZHANG Yu-ping; ZHANG Yi-Jun; XU Guang-ri; WEI Xin-jun; LEE Kwang-pill


    Development of effective chromatographic or electrophoretic separation involves judicious deciding of selection of optimal experimental conditions that can provide an adequate resolution at a reasonable run time for the separation of interested components. Box-Behnken factorial design was effectively applied for the separation optimization of eight structurally related sulfonamides using capillary zone electrophorosis and reverse high performance liquid chromatography. Optimum values for volume ratio of THF to H2O in eluent, column temperature and flow rate of eluent are found as 12 to 88, 35 ℃ and 1.0 mL/min, respectively.Box-Behnken modified optimization model is extended to separation by capillary electrophoresis (CE). While using CE, a satisfactory separation is achieved with a minimum resolution larger than 1.0 for a separation time less than 10 min.

  2. Filling of charged cylindrical capillaries

    NARCIS (Netherlands)

    Das, Siddhartha; Chanda, Sourayon; Eijkel, J.C.T.; Tas, N.R.; Chakraborty, Suman; Mitra, Sushanta K.


    We provide an analytical model to describe the filling dynamics of horizontal cylindrical capillaries having charged walls. The presence of surface charge leads to two distinct effects: It leads to a retarding electrical force on the liquid column and also causes a reduced viscous drag force because

  3. Capillary thinning of polymeric filaments

    DEFF Research Database (Denmark)

    Kolte, Mette Irene; Szabo, Peter


    The capillary thinning of filaments of a Newtonian polybutene fluid and a viscoelastic polyisobutylene solution are analyzed experimentally and by means of numerical simulation. The experimental procedure is as follows. Initially, a liquid sample is placed between two cylindrical plates. Then, th...... and quantified. (C) 1999 The Society of Rheology. [S0148-6055(99)00103-0]....

  4. Draft Genome Sequences of Eight Nontypeable Haemophilus influenzae Strains Previously Characterized Using an Electrophoretic Typing Scheme. (United States)

    Mussa, Huda J; VanWagoner, Timothy M; Morton, Daniel J; Seale, Thomas W; Whitby, Paul W; Stull, Terrence L


    Nontypeable Haemophilus influenzae is an important cause of human disease. Strains were selected for genome sequencing to represent the breadth of nontypeable strains within the species, as previously defined by the electrophoretic mobility of 16 metabolic enzymes.

  5. Improved design of electrophoretic equipment for rapid sickle-cell-anemia screening (United States)

    Reddick, J. M.; Hirsch, I.


    Effective mass screening may be accomplished by modifying existing electrophoretic equipment in conjunction with multisample applicator used with cellulose-acetate-matrix test paper. Using this method, approximately 20 to 25 samples can undergo electrophoresis in 5 to 6 minutes.

  6. Coated capillaries with highly charged polyelectrolytes and carbon nanotubes co-aggregated with sodium dodecyl sulphate for the analysis of sulfonylureas by capillary electrophoresis. (United States)

    El-Debs, Racha; Nehmé, Reine; Claude, Bérengère; Motteau, Solène; Togola, Anne; Berho, Catherine; Morin, Philippe


    Sulfonylureas (SUs) are one of the most widely used herbicides to control weeds in crops. Herein, capillary electrophoresis (CE) was used to determine four sulfonylureas in natural waters, namely chlorsulfuron (CS), iodosulfuron methyl (IM), metsulfuron methyl (MSM) and mesosulfuron methyl (MSS). First of all, a bare silica capillary was chosen with 10mM of 1-butyl-3-methylimidazolium tetrafluoroborate (bminBF4) as electrophoretic buffer (pH 9.6) containing 2 mg L(-1) of surfactant-coated single-wall carbon nanotubes (SC-SWCNTs). A dramatic deviation in migration times was observed. Therefore, a poly(diallyldimethylammonium) chloride (PDADMAC) statically coated cationic capillary was used to improve repeatability and to alter the selectivity of the separation. The electroosmotic flow (EOF) measurement revealed that the SC-SWCNTs were strongly adsorbed at the surface of the PDADMAC coating even in the absence of the surfactant-coated nanotubes in the electrolyte buffer. Consequently, a stable strong cathodic EOF and excellent repeatabilities were obtained with relative standard deviations (RSDs) on migration times and on corrected peak areas below 0.9 and 1.5%, respectively. The separation of the SUs was conducted in only 6 min. No regeneration of the coating between analyses was necessary, and high peak efficiencies up to 173,000 theoretical plates were obtained. The bi-layer coating was subsequently used to analyze sulfonylureas in tap water, in several mineral waters as well as in underground waters spiked with SUs and directly injected into the CE capillary.

  7. Capillary electrophoresis analysis of different variants of the amyloidogenic protein β2 -microglobulin as a simple tool for misfolding and stability studies. (United States)

    Bertoletti, Laura; Bisceglia, Federica; Colombo, Raffaella; Giorgetti, Sofia; Raimondi, Sara; Mangione, P Patrizia; De Lorenzi, Ersilia


    Free solution capillary electrophoresis with UV detection is here used to retrieve information on the conformational changes of wild-type β2 -microglobulin and a series of naturally and artificially created variants known to have different stability and amyloidogenic potential. Under nondenaturing conditions, the resolution of at least two folding conformers at equilibrium is obtained and a third species is detected for the less stable isoforms. Partial denaturation by using chaotropic agents such as acetonitrile or trifluoroethanol reveals that the separated peaks are at equilibrium, as the presence of less structured species is either enhanced or induced at the expenses of the native form. Reproducible CE data allow to obtain an interesting semiquantitative correlation between the peak areas observed and the protein stability. Thermal unfolding over the range 25-42°C is induced inside the capillary for the two pathogenic proteins (wtβ2 -microglobulin and D76N variant): the large differences observed upon small temperature variation draw attention on the robustness of analytical methods when dealing with proteins prone to misfolding and aggregation.

  8. Metabolic cytometry: capillary electrophoresis with two-color fluorescence detection for the simultaneous study of two glycosphingolipid metabolic pathways in single primary neurons. (United States)

    Essaka, David C; Prendergast, Jillian; Keithley, Richard B; Palcic, Monica M; Hindsgaul, Ole; Schnaar, Ronald L; Dovichi, Norman J


    Metabolic cytometry is a form of chemical cytometry wherein metabolic cascades are monitored in single cells. We report the first example of metabolic cytometry where two different metabolic pathways are simultaneously monitored. Glycolipid catabolism in primary rat cerebella neurons was probed by incubation with tetramethylrhodamine-labeled GM1 (GM1-TMR). Simultaneously, both catabolism and anabolism were probed by coincubation with BODIPY-FL labeled LacCer (LacCer-BODIPY-FL). In a metabolic cytometry experiment, single cells were incubated with substrate, washed, aspirated into a capillary, and lysed. The components were separated by capillary electrophoresis equipped with a two-spectral channel laser-induced fluorescence detector. One channel monitored fluorescence generated by the metabolic products produced from GM1-TMR and the other monitored the metabolic products produced from LacCer-BODIPY-FL. The metabolic products were identified by comparison with the mobility of a set of standards. The detection system produced at least 6 orders of magnitude dynamic range in each spectral channel with negligible spectral crosstalk. Detection limits were 1 zmol for BODIPY-FL and 500 ymol for tetramethylrhodamine standard solutions.

  9. Effect of passage number on electrophoretic mobility distributions of cultured human embryonic kidney cells (United States)

    Kunze, M. E.


    A systematic investigation was undertaken to characterize population shifts that occur in cultured human embryonic kidney cells as a function of passage number in vitro after original explantation. This approach to cell population shift analysis follows the suggestion of Mehreshi, Klein and Revesz that perturbed cell populations can be characterized by electrophoretic mobility distributions if they contain subpopulations with different electrophoretic mobilities. It was shown that this is the case with early passage cultured human embryo cells.

  10. Determination of biogenic amines in beer and wine by capillary electrophoresis-tandem mass spectrometry. (United States)

    Daniel, Daniela; Dos Santos, Vagner Bezerra; Vidal, Denis Tadeu Rajh; do Lago, Claudimir Lucio


    A capillary electrophoresis-tandem mass spectrometry (CE-MS/MS) method for the simultaneous assessment of nine biogenic amines (spermine, spermidine, putrescine, cadaverine, histamine, phenylethylamine, tryptamine, tyramine, and urocanic acid) in commercial samples of beer and wine is introduced. The samples were submitted to a simple clean-up step with poly(vinylpolypyrrolidone) followed by filtration. Electrophoretic separation in a polyvinyl alcohol (PVA)-coated capillary using 0.5 mol L(-1) acetic acid (pH 2.5) as background electrolyte and detection by electrospray-tandem mass spectrometry was employed. The range of the correlation coefficients of the calibration curves of the analyzed compounds was 0.996-0.999, and the limits of detection and limits of quantification were in the range of 1-2 μg L(-1) and 3-8 μg L(-1), respectively. The recovery values for samples spiked at three concentration levels (0.2, 0.5, and 1.0 mg L(-1)) ranged from 87 to 113% with standard deviation not greater than 5.8%. The use of a PVA-coated silica capillary allows suppressing the electroosmotic flow and, consequently, increasing of the separation efficiency. The method was successfully used to determine biogenic amines in commercial samples of beer and wine.

  11. Effect of Artemisia capillaries on Gene Expression of Lipid Metabolism in Rat

    Directory of Open Access Journals (Sweden)

    Woo-Seok Jang


    Full Text Available Objective :The purpose of this study is to evaluate the effect of Artemisia capillaries on gene expression of lipid metabolism in rats. Method :The author performed several experimental items to analyze the total cholesterol and triglyceride in liver tissue, the gene expressions of CYP7A1 and HMG-CoA reductase. Results :1. In Artemisia capillaries group, the levels of total cholesterol in liver tissue were significantly decreased. 2. In Artemisia capillaries group, the ratios of CYP7A1, HMG-CoA reductase were as same as the normal group. Conclusion :From the above results, Artemisia capillaries can be used to treat hyperlipidemia.

  12. Electrochemical methods in conjunction with capillary and microchip electrophoresis. (United States)

    Mark, Jonas J P; Scholz, Rebekka; Matysik, Frank-Michael


    Electromigrative techniques such as capillary and microchip electrophoresis (CE and MCE) are inherently associated with various electrochemical phenomena. The electrolytic processes occurring in the buffer reservoirs have to be considered for a proper design of miniaturized electrophoretic systems and a suitable selection of buffer composition. In addition, the control of the electroosmotic flow plays a crucial role for the optimization of CE/MCE separations. Electroanalytical methods have significant importance in the field of detection in conjunction with CE/MCE. At present, amperometric detection and contactless conductivity detection are the predominating electrochemical detection methods for CE/MCE. This paper reviews the most recent trends in the field of electrochemical detection coupled to CE/MCE. The emphasis is on methodical developments and new applications that have been published over the past five years. A rather new way for the implementation of electrochemical methods into CE systems is the concept of electrochemically assisted injection which involves the electrochemical conversions of analytes during the injection step. This approach is particularly attractive in hyphenation to mass spectrometry (MS) as it widens the range of CE-MS applications. An overview of recent developments of electrochemically assisted injection coupled to CE is presented.

  13. The impact of capillary dilation on the distribution of red blood cells in artificial networks. (United States)

    Schmid, Franca; Reichold, Johannes; Weber, Bruno; Jenny, Patrick


    Recent studies suggest that pericytes around capillaries are contractile and able to alter the diameter of capillaries. To investigate the effects of capillary dilation on network dynamics, we performed simulations in artificial capillary networks of different sizes and complexities. The unequal partition of hematocrit at diverging bifurcations was modeled by assuming that each red blood cell (RBC) enters the branch with the faster instantaneous flow. Network simulations with and without RBCs were performed to investigate the effect of local dilations. The results showed that the increase in flow rate due to capillary dilation was less when the effects of RBCs are included. For bifurcations with sufficient RBCs in the parent vessel and nearly equal flows in the branches, the flow rate in the dilated branch did not increase. Instead, a self-regulation of flow was observed due to accumulation of RBCs in the dilated capillary. A parametric study was performed to examine the dependence on initial capillary diameter, dilation factor, and tube hematocrit. Furthermore, the conditions needed for an efficient self-regulation mechanism are discussed. The results support the hypothesis that RBCs play a significant role for the fluid dynamics in capillary networks and that it is crucial to consider the blood flow rate and the distribution of RBCs to understand the supply of oxygen in the vasculature. Furthermore, our results suggest that capillary dilation/constriction offers the potential of being an efficient mechanism to alter the distribution of RBCs locally and hence could be important for the local regulation of oxygen delivery.

  14. Fast and sensitive method to determine parabens by capillary electrophoresis using automatic reverse electrode polarity stacking mode: application to hair samples. (United States)

    Sako, Alysson V F; Dolzan, Maressa D; Micke, Gustavo Amadeu


    This paper describes a fast and sensitive method for the determination of methyl, ethyl, propyl, and butylparaben in hair samples by capillary electrophoresis using automatic reverse electrode polarity stacking mode. In the proposed method, solutions are injected using the flush command of the analysis software (940 mbar) and the polarity switching is carried out automatically immediately after the sample injection. The advantages compared with conventional stacking methods are the increased analytical frequency, repeatability, and inter-day precision. All analyses were performed in a fused silica capillary (50 cm, 41.5 cm in effective length, 50 μm i.d.), and the background electrolyte was composed of 20 mmol L(-1) sodium tetraborate in 10 % of methanol, pH 9.3. For the reverse polarity, -25 kV/35 s was applied followed by application of +30 kV for the electrophoretic run. Temperature was set at 20 °C, and all analytes were monitored at 297 nm. The method showed acceptable linearity (r (2) > 0.997) in the studied range of 0.1-5.0 mg L(-1), limits of detection below 0.017 mg L(-1), and inter-day, intra-day, and instrumental precision better than 6.2, 3.6, and 4.6 %, respectively. Considering parabens is widely used as a preservative in many products and the reported possibility of damage to the hair and also to human health caused by these compounds, the proposed method was applied to evaluate the adsorption of parabens in hair samples. The results indicate that there is a greater adsorption of methylparaben compared to the other parabens tested and also dyed hairs had a greater adsorption capacity for parabens than natural hairs.

  15. A novel capillary electrophoresis method with pressure assisted field amplified sample injection in determination of thiol collectors in flotation process waters. (United States)

    Sihvonen, T; Aaltonen, A; Leppinen, J; Hiltunen, S; Sirén, H


    A new capillary electrophoresis method was developed for the quantification of diisobutyldithiophosphate (DTP), diisobutyldithiophosphinate (DTPI) and ethyl and isobutyl xanthates (EX, IBX) all of which are used as thiol collectors in froth flotation. This method uses pressure assisted field amplified sample injection (PA-FASI) to concentrate the analytes at the capillary inlet. The background electrolyte in electrophoretic separation was 60millimolar (mM) from 3-(cyclohexylamino)propane-1-sulfonic acid (CAPS) in 40mM NaOH solution. The similar CAPS electrolyte solution has earlier been used for screening for diuretics that contained sulphonamide and/or carboxylic groups. In this study, the functional groups are xanthate, phosphate and phosphinate. The method was developed using actual flotation process waters. The results showed that the water delivered from the plant did not contain significant amount of collectors; therefore, method development was accomplished by spiking analytes in these waters. Separation of analytes was achieved in 15min. The range of quantification was 0.27-66.6mg/L (R(2) 0.9991-0.9999) for all analytes other than ethyl xanthate, for which the range was 0.09-66.6mg/L (R(2) 0.9999). LOD (S/N=3) and LOQ (S/N=10) values for DTP, DTPI, IBX and EX were 0.05, 0.07, 0.06 and 0.01mg/L and 0.16, 0.25, 0.21 and 0.04mg/L, respectively. No interference from the matrices was observed, when the method was tested at a gold concentrator plant.

  16. Optimization of affinity capillary electrophoresis for routine investigations of protein-metal ion interactions. (United States)

    Alhazmi, Hassan A; Deeb, Sami El; Nachbar, Markus; Redweik, Sabine; Albishri, Hassan M; El-Hady, Deia Abd; Wätzig, Hermann


    To facilitate the implementation of affinity capillary electrophoresis into routine binding screening studies of proteins with metal ions, method acceleration, transfer and precision improvement were investigated. Affinity capillary electrophoresis was accelerated by using shorter capillaries, employing lower sample concentrations and smaller injection volumes. Intra- and inter-instrument method transfers were investigated considering the temperature setting of the capillary cooling system. For intra-instrument method transfer, similar results were obtained when transferring a method from a long (62 cm) to a short (31 cm) capillary. The analysis time was reduced from 9 to 4 min. In case of inter-instrument method transfer, interaction results showed small variation on the capillary electrophoresis instrument with inefficient capillary cooling system. Binding measurement precision was enhanced by slightly pushing the sample above the beginning of the capillary. Changing the buffer vials after each 30 runs and employing extra flushing after each 60 subsequent runs further enhanced the precision. The use of 0.1 molar ethylenediaminetetraacetic acid in the rinsing solution successfully desorbs the remaining metal ions from the capillary wall. Excellent precision for apparent mobility ratio measurements was achieved for different protein-metal ion interactions (relative standard deviation of 0.16-0.89%, 15 series, 12 runs for each).

  17. A plasmid containing the human metallothionein II gene can function as an antibody-assisted electrophoretic biosensor for heavy metals. (United States)

    Wooten, Dennis C; Starr, Clarise R; Lyon, Wanda J


    Different forms of heavy metals affect biochemical systems in characteristic ways that cannot be detected with typical metal analysis methods like atomic absorption spectrometry. Further, using living systems to analyze interaction of heavy metals with biochemical systems can be laborious and unreliable. To generate a reliable easy-to-use biologically-based biosensor system, the entire human metallothionein-II (MT-II) gene was incorporated into a plasmid (pUC57-MT) easily replicated in Escherichia coli. In this system, a commercial polyclonal antibody raised against human metal-responsive transcription factor-1 protein (MTF-1 protein) could modify the electrophoretic migration patterns (i.e. cause specific decreases in agarose gel electrophoretic mobility) of the plasmid in the presence or absence of heavy metals other than zinc (Zn). In the study here, heavy metals, MTF-1 protein, and polyclonal anti-MTF-1 antibody were used to assess pUC57-MT plasmid antibody-assisted electrophoretic mobility. Anti-MTF-1 antibody bound both MTF-1 protein and pUC57-MT plasmid in a non-competitive fashion such that it could be used to differentiate specific heavy metal binding. The results showed that antibody-inhibited plasmid migration was heavy metal level-dependent. Zinc caused a unique mobility shift pattern opposite to that of other metals tested, i.e. Zn blocked the antibody ability to inhibit plasmid migration, despite a greatly increased affinity for DNA by the antibody when Zn was present. The Zn effect was reversed/modified by adding MTF-1 protein. Additionally, antibody inhibition of plasmid mobility was resistant to heat pre-treatment and trypsinization, indicating absence of residual DNA extraction-resistant bacterial DNA binding proteins. DNA binding by anti-DNA antibodies may be commonly enhanced by xenobiotic heavy metals and elevated levels of Zn, thus making them potentially effective tools for assessment of heavy metal bioavailability in aqueous solutions and

  18. Use of neutral capillaries for the enantioseparation of N-benzoylated amino acids by capillary electrophoresis with bromobalhimycin as chiral selector. (United States)

    Peng, Yongbo; Zhang, Tingting; Wang, Tingting; Liu, Zhenghua; Crommen, Jacques; Jiang, Zhengjin


    In this study, the partial filling technique on both polycationic polymer hexadimethrine bromide (HDB) modified capillary and eCAP neutral capillary were systematically compared in order to enhance the enantioseparation ability of bromobalhimycin as CE additive. The separation conditions, such as pH, the plug length, and the concentration of bromobalhimycin, etc., were optimized in order to obtain satisfactory separations. As expected, for all tested 28 N-benzoylated amino acids, up to five times higher enantioresolutions were obtained on the eCAP neutral capillary compared to that on the polycationic polymer hexadimethrine bromide modified capillary. Moreover, 26 of 28 tested racemic compounds were almost baseline- resolved without observing any interference from the front of the plug of bromobalhimycin. Although the limitation of longer running time on the neutral capillary, it allows the use of higher content of bromobalhimycin in the running buffer without any interference on the detection of analytes when enantioseparations are more difficult to obtain.

  19. Electrophoretic deposition and constrained sintering of strontium titanate thick films

    Energy Technology Data Exchange (ETDEWEB)

    Amaral, Luís; Vilarinho, Paula M., E-mail:; Senos, Ana M.R.


    Thick films of functional oxides are currently substituting counterparts bulk ceramics, as in the case of low loss dielectrics. For SrTiO{sub 3} (ST) based compositions it is demonstrated that electrophoretic deposition (EPD), using acetone as a suspension media with iodine addition, is a suitable technology to fabricate 12 μm thick films. The microstructural analysis of the films sintered at 1500 °C shows that highly densified microstructures can be obtained and, by slightly varying the Sr/Ti stoichiometry in the powder composition, increased densification and grain size and enlargement of the distribution with decreasing Sr/Ti ratio can be observed. In spite of the high densification of the films, it is also demonstrated that due to the constraint imposed by the substrate a smaller grain size is observed in thick films as compared to equivalent bulk ceramics. In addition, a preferential vertical pore orientation is observed in ST thick films. These results may have broad implications if one considers that the dielectric losses and dielectric tunability is affected by pore orientation, since it affects the electric field distribution. - Highlights: • Nonstoichiometry effect on microstructure of constrained sintered thick films and bulk is similar. • Increased densification and grain size and enlargement of distribution with decreasing Sr/Ti ratio. • Independent of Sr/Ti ratio smaller grain size for thick films compared to ceramics. • Preferential vertical pore orientation for constrained sintering of thick films. • Anisotropic porosity as tailoring factor to engineer permittivity and tunability.

  20. Optimization of a microfluidic electrophoretic immunoassay using a Peltier cooler. (United States)

    Mukhitov, Nikita; Yi, Lian; Schrell, Adrian M; Roper, Michael G


    Successful analysis of electrophoretic affinity assays depends strongly on the preservation of the affinity complex during separations. Elevated separation temperatures due to Joule heating promotes complex dissociation leading to a reduction in sensitivity. Affinity assays performed in glass microfluidic devices may be especially prone to this problem due to poor heat dissipation due to the low thermal conductivity of glass and the large amount of bulk material surrounding separation channels. To address this limitation, a method to cool a glass microfluidic chip for performing an affinity assay for insulin was achieved by a Peltier cooler localized over the separation channel. The Peltier cooler allowed for rapid stabilization of temperatures, with 21°C the lowest temperature that was possible to use without producing detrimental thermal gradients throughout the device. The introduction of cooling improved the preservation of the affinity complex, with even passive cooling of the separation channel improving the amount of complex observed by 2-fold. Additionally, the capability to thermostabilize the separation channel allowed for utilization of higher separation voltages than what was possible without temperature control. Kinetic CE analysis was utilized as a diagnostic of the affinity assay and indicated that optimal conditions were at the highest separation voltage, 6 kV, and the lowest separation temperature, 21°C, leading to 3.4% dissociation of the complex peak during the separation. These optimum conditions were used to generate a calibration curve and produced 1 nM limits of detection, representing a 10-fold improvement over non-thermostated conditions. This methodology of cooling glass microfluidic devices for performing robust and high sensitivity affinity assays on microfluidic systems should be amenable in a number of applications.

  1. Effective viscosity of magnetic nanofluids through capillaries. (United States)

    Patel, Rajesh


    The simultaneous effect of magnetic field and temperature on the capillary viscosity of magnetic nanofluid is an important parameter for a new class of applications such as nanoduct flow, nanomotors, micro- and nanofluidic devices, for transformer cooling, magnetic targeted drug delivery, etc. The effective viscosity of a nanofluid is explained based on the rotation of the particles and the effect of torque on it due to an externally applied magnetic field. Two types of fluids are used here, temperature-sensitive and non-temperature-sensitive magnetic nanofluids. In both types of fluids, decrease in effective viscosity with temperature is observed, but in both cases the mechanism for the decrement is quite different. One is due to temperature dependence of the magnetic moment and the other is due to removal of the secondary surfactant. For temperature-sensitive magnetic nanofluids, a Curie temperature of ~80 °C is extracted from this study. For non-temperature-sensitive magnetic nanofluids ~65% of the secondary surfactant is removed for a change in temperature, ΔT = 40 °C. This is analogous with removal of a drug from magnetic particles for targeted drug delivery. Further, a linear dependence of effective viscosity with different capillary size and ξ (angle between magnetic field and flow direction, ξε[0,π/2]) is also observed. This linear dependence can also be a good approximation for the study of magnetic drug targeting, as in the human body the capillaries are of different sizes, and the externally applied magnetic field is not always parallel or perpendicular to the drug flow direction.

  2. Comparison of different approaches for evaluation of the detection and quantitation limits of a purity method: a case study using a capillary isoelectrofocusing method for a monoclonal antibody. (United States)

    Apostol, Izydor; Miller, Karen J; Ratto, Joseph; Kelner, Drew N


    Several different techniques suggested by the International Conference on Harmonization (ICH) Q2R1 guideline were used to assess the signal and concentration at the limit of detection (LOD) and limit of quantitation (LOQ) for a purity method. These approaches were exemplified with a capillary isoelectrofocusing (cIEF) method, which has been developed to quantify the distribution of the charge isoforms of a monoclonal antibody. The charge isoforms are the result of incomplete posttranslational processing of C-terminal lysine residues of the heavy chain by carboxypeptidase. Results showed no significant discrepancy between LOD/LOQ obtained by the different techniques. Validation experiments corroborated the calculated LOQ. The results indicate that any single technique can provide meaningful values for the LOD and LOQ. Finally, important points to consider when applying these techniques to purity methods are discussed.

  3. Hemoglobin measured by Hemocue and a reference method in venous and capillary blood: a validation study Hemoglobina medida por Hemocue y por un método de referencia en sangre venosa y capilar: estudio de validación



    Objective. To assess the comparability of hemoglobin concentration (Hb) in venous and capillary blood measured by Hemocue and an automated spectrophotometer (Celldyn) and to document the influence of type of blood (capillary or venous) and analysis method on anemia prevalence estimates. Material and Methods. Between February and May 2000, capillary and venous samples were collected from 72 adults and children at Hospital del Niño Morelense (Morelos State Children's Hospital) in Cuernavaca, Mo...

  4. 'Click' chemistry synthesis and capillary electrophoresis study of 1,4-linked 1,2,3-triazole AZT-systemin conjugate. (United States)

    Dobkowski, Michał; Szychowska, Aleksandra; Pieszko, Małgorzata; Miszka, Anna; Wojciechowska, Monika; Alenowicz, Magdalena; Ruczyński, Jarosław; Rekowski, Piotr; Celewicz, Lech; Barciszewski, Jan; Mucha, Piotr


    The Cu(I) catalyzed Huisgen 1,3-dipolar azide-alkyne cycloaddition (CuAAC) was applied for a nucleoside-peptide bioconjugation. Systemin (Sys), an 18-aa plant signaling peptide naturally produced in response to wounding or pathogen attack, was chemically synthesized as its N-propynoic acid functionalized analog (Prp-Sys) using the SPPS. Next, CuAAC was applied to conjugate Prp-Sys with 3'-azido-2',3'-dideoxythymidine (AZT), a model cargo molecule. 1,4-Linked 1,2,3-triazole AZT-Sys conjugate was designed to characterize the spreading properties and ability to translocate of cargo molecules of systemin. CuAAC allowed the synthesis of the conjugate in a chemoselective and regioselective manner, with high purity and yield. The presence of Cu(I) ions generated in situ drove the CuAAC reaction to completion within a few minutes without any by-products. Under typical separation conditions of phosphate 'buffer' at low pH and uncoated fused bare-silica capillary, an increasing peak intensity assigned to triazole-linked AZT-Sys conjugate was observed using capillary electrophoresis (CE) during CuAAC. CE analysis showed that systemin peptides are stable in tomato leaf extract for up to a few hours. CE-ESI-MS revealed that the native Sys and its conjugate with AZT are translocated through the tomato stem and can be directly detected in stem exudates. The results show potential application of systemin as a transporter of low molecular weight cargo molecules in tomato plant and of CE method to characterize a behavior of plant peptides and its analogs.

  5. Capillary electrophoresis of intact basic proteins using noncovalently triple-layer coated capillaries. (United States)

    Haselberg, Rob; de Jong, Gerhardus J; Somsen, Govert W


    The usefulness of a noncovalent, positively charged capillary coating for the efficient analysis of intact basic proteins with CE was studied. Capillaries were coated by subsequent flushing with solutions of 10% w/v Polybrene (PB), 3% w/v dextran sulfate (DS), and again 10% w/v PB. Coating characterization studies showed that stable coatings could be produced which exhibited a pH-independent and highly reproducible EOF. The PB-DS-PB coating was evaluated with Tris phosphate BGEs of various pH using the four basic model proteins: alpha-chymotrypsinogen A, ribonuclease A, cytochrome c, and lysozyme. Typical migration time RSDs for the proteins were less than 0.85%, and apparent plate numbers were above 125,000 using a capillary length of 40 cm. The high separation efficiency allowed detection of several minor impurities in the model proteins. Using a BGE of medium pH, the CE system with triple-layer coating appeared to be useful for the repeatable profiling of recombinant humanized mouse monoclonal immunoglobulin G(1) showing a characteristic pattern of glycoforms. The CE system was also applied to the characterization of two llama antibodies, which were produced in Saccharomyces cerevisiae, revealing the presence of a side product in one of the antibodies. The high migration time stability allowed the reliable determination of antibody-antigen binding by monitoring migration time shifts. Finally, the feasibility of using the PB-DS-PB coated capillaries for CE with mass spectrometric detection was shown by the characterization of the impure llama antibody sample.

  6. The capillary hysteresis model HYSTR: User`s guide

    Energy Technology Data Exchange (ETDEWEB)

    Niemi, A.; Bodvarsson, G.S.


    The potential disposal of nuclear waste in the unsaturated zone at Yucca Mountain, Nevada, has generated increased interest in the study of fluid flow through unsaturated media. In the near future, large-scale field tests will be conducted at the Yucca Mountain site, and work is now being done to design and analyze these tests. As part of these efforts a capillary hysteresis model has been developed. A computer program to calculate the hysteretic relationship between capillary pressure {phi} and liquid saturation (S{sub 1}) has been written that is designed to be easily incorporated into any numerical unsaturated flow simulator that computes capillary pressure as a function of liquid saturation. This report gives a detailed description of the model along with information on how it can be interfaced with a transport code. Although the model was developed specifically for calculations related to nuclear waste disposal, it should be applicable to any capillary hysteresis problem for which the secondary and higher order scanning curves can be approximated from the first order scanning curves. HYSTR is a set of subroutines to calculate capillary pressure for a given liquid saturation under hysteretic conditions.

  7. Silver nanoparticle-doped zirconia capillaries for enhanced bacterial filtration. (United States)

    Wehling, Julia; Köser, Jan; Lindner, Patrick; Lüder, Christian; Beutel, Sascha; Kroll, Stephen; Rezwan, Kurosch


    Membrane clogging and biofilm formation are the most serious problems during water filtration. Silver nanoparticle (Agnano) coatings on filtration membranes can prevent bacterial adhesion and the initiation of biofilm formation. In this study, Agnano are immobilized via direct reduction on porous zirconia capillary membranes to generate a nanocomposite material combining the advantages of ceramics being chemically, thermally and mechanically stable with nanosilver, an efficient broadband bactericide for water decontamination. The filtration of bacterial suspensions of the fecal contaminant Escherichia coli reveals highly efficient bacterial retention capacities of the capillaries of 8 log reduction values, fulfilling the requirements on safe drinking water according to the U.S. Environmental Protection Agency. Maximum bacterial loading capacities of the capillary membranes are determined to be 3×10(9)bacterialcells/750mm(2) capillary surface until back flushing is recommendable. The immobilized Agnano remain accessible and exhibit strong bactericidal properties by killing retained bacteria up to maximum bacterial loads of 6×10(8)bacterialcells/750mm(2) capillary surface and the regenerated membranes regain filtration efficiencies of 95-100%. Silver release is moderate as only 0.8% of the initial silver loading is leached during a three-day filtration experiment leading to average silver contaminant levels of 100μg/L.

  8. Retinal Capillary Rarefaction in Patients with Type 2 Diabetes Mellitus (United States)

    Jumar, Agnes; Harazny, Joanna M.; Ott, Christian; Friedrich, Stefanie; Kistner, Iris; Striepe, Kristina


    Purpose In diabetes mellitus type 2, capillary rarefaction plays a pivotal role in the pathogenesis of end-organ damage. We investigated retinal capillary density in patients with early disease. Methods This cross-sectional study compares retinal capillary rarefaction determined by intercapillary distance (ICD) and capillary area (CapA), measured non-invasively and in vivo by scanning laser Doppler flowmetry, in 73 patients with type 2 diabetes, 55 healthy controls and 134 individuals with hypertension stage 1 or 2. Results In diabetic patients, ICD was greater (23.2±5.5 vs 20.2±4.2, p = 0.013) and CapA smaller (1592±595 vs 1821±652, p = 0.019) than in healthy controls after adjustment for differences in cardiovascular risk factors between the groups. Compared to hypertensive patients, diabetic individuals showed no difference in ICD (23.1±5.8, p = 0.781) and CapA (1556±649, p = 0.768). Conclusion In the early stage of diabetes type 2, patients showed capillary rarefaction compared to healthy individuals. PMID:27935938

  9. Manufacturing of flat porous structures for capillary pump applications

    Energy Technology Data Exchange (ETDEWEB)

    Reimbrecht, E.G.; Wendhausen, P.A.P.; Fredel, M.C.; Bazzo, E. [Dept. of Mechanical Engineering, Univ. Federal de Santa Catarina-UFSC, Florianopolis (Brazil)


    A flat porous structure is proposed to be used as wick in capillary pumps to move the working fluid in two-phase heat transfer loops. Capillary pumps have been studied to become a reliable alternative for isothermalization and thermal control of satellites and space stations. Sintered nickel powder is an alternative to produce capillary structures, once it presents appropriate sinterability and it is compatible with current working fluids (e.g. ammonia). The desirable parameters for the capillary structure are a porosity level of about 60% and a mean pore size smaller than 10 {mu}m. The flat porous elements was produced by a loose powder sintering and powder injection molding. Powder size and shape, sintering process, sintering time and sintering temperature, were investigated in order to achieve the desired porosity and mechanical resistance. Analyses were accomplished to characterize the capillary structure, and to determine the appropriate manufacturing route. The porosity was determined by using the method of Arquimedes and the porous structures analyzed by scanning electron microscopy. (orig.)

  10. On the performance of capillary barriers as landfill cover (United States)

    Kämpf, M.; Montenegro, H.

    Landfills and waste heaps require an engineered surface cover upon closure. The capping system can vary from a simple soil cover to multiple layers of earth and geosynthetic materials. Conventional design features a compacted soil layer, which suffers from drying out and cracking, as well as root and animal intrusion. Capillary barriers consisting of inclined fine-over-coarse soil layers are investigated as an alternative cover system. Under unsaturated conditions, the textural contrast delays vertical drainage by capillary forces. The moisture that builds up above the contact will flow downdip along the interface of the layers. Theoretical studies of capillary barriers have identified the hydraulic properties of the layers, the inclination angle, the length of the field and the infiltration rate as the fundamental characteristics of the system. However, it is unclear how these findings can lead to design criteria for capillary barriers. To assess the uncertainty involved in such approaches, experiments have been carried out in a 8 m long flume and on large scale test sites (40 m x 15 m). In addition, the ability of a numerical model to represent the relevant flow processes in capillary barriers has been examined.

  11. On the performance of capillary barriers as landfill cover

    Directory of Open Access Journals (Sweden)

    M. Kämpf


    Full Text Available Landfills and waste heaps require an engineered surface cover upon closure. The capping system can vary from a simple soil cover to multiple layers of earth and geosynthetic materials. Conventional design features a compacted soil layer, which suffers from drying out and cracking, as well as root and animal intrusion. Capillary barriers consisting of inclined fine-over-coarse soil layers are investigated as an alternative cover system. Under unsaturated conditions, the textural contrast delays vertical drainage by capillary forces. The moisture that builds up above the contact will flow downdip along the interface of the layers. Theoretical studies of capillary barriers have identified the hydraulic properties of the layers, the inclination angle, the length of the field and the infiltration rate as the fundamental characteristics of the system. However, it is unclear how these findings can lead to design criteria for capillary barriers. To assess the uncertainty involved in such approaches, experiments have been carried out in a 8 m long flume and on large scale test sites (40 m x 15 m. In addition, the ability of a numerical model to represent the relevant flow processes in capillary barriers has been examined.

  12. Triple-channel portable capillary electrophoresis instrument with individual background electrolytes for the concurrent separations of anionic and cationic species. (United States)

    Mai, Thanh Duc; Le, Minh Duc; Sáiz, Jorge; Duong, Hong Anh; Koenka, Israel Joel; Pham, Hung Viet; Hauser, Peter C


    The portable capillary electrophoresis instrument is automated and features three independent channels with different background electrolytes to allow the concurrent optimized determination of three different categories of charged analytes. The fluidic system is based on a miniature manifold which is based on mechanically milled channels for injection of samples and buffers. The planar manifold pattern was designed to minimize the number of electronic valves required for each channel. The system utilizes pneumatic pressurization to transport solutions at the grounded as well as the high voltage side of the separation capillaries. The instrument has a compact design, with all components arranged in a briefcase with dimensions of 45 (w) × 35 (d) × 15 cm (h) and a weight of about 15 kg. It can operate continuously for 8 h in the battery-powered mode if only one electrophoresis channel is in use, or for about 2.5 h in the case of simultaneous employment of all three channels. The different operations, i.e. capillary flushing, rinsing of the interfaces at both capillary ends, sample injection and electrophoretic separation, are activated automatically with a control program featuring a graphical user interface. For demonstration, the system was employed successfully for the concurrent separation of different inorganic cations and anions, organic preservatives, additives and artificial sweeteners in various beverage and food matrices.

  13. Accurate determination of peptide phosphorylation stoichiometry via automated diagonal capillary electrophoresis coupled with mass spectrometry: proof of principle. (United States)

    Mou, Si; Sun, Liangliang; Dovichi, Norman J


    While reversible protein phosphorylation plays an important role in many cellular processes, simple and reliable measurement of the stoichiometry of phosphorylation can be challenging. This measurement is confounded by differences in the ionization efficiency of phosphorylated and unphosphorylated sites during analysis by mass spectrometry. Here, we demonstrate diagonal capillary electrophoresis-mass spectrometry for the accurate determination of this stoichiometry. Diagonal capillary electrophoresis is a two-dimensional separation method that incorporates an immobilized alkaline phosphatase microreactor at the distal end of the first capillary and employs identical electrophoretic separation modes in both dimensions. The first dimension is used to separate a mixture of the phosphorylated and unphosphorylated forms of a peptide. Fractions are parked in the reactor where they undergo complete dephosphorylation. The products are then periodically transferred to the second capillary and analyzed by mass spectrometry (MS). Because the phosphorylated and unphosphorylated forms differ in charge, they are well resolved in the first dimension separation. Because the unphosphorylated and dephosphorylated peptides are identical, there is no bias in ionization efficiency, and phosphorylation stoichiometry can be determined by the ratio of the signal of the two forms. A calibration curve was generated from mixtures of a phosphorylated standard peptide and its unphosphorylated form, prepared in a bovine serum albumin tryptic digest. This proof of principle experiment demonstrated a linear response across nearly 2 orders of magnitude in stoichiometry.

  14. Development and characterization of a novel semiautomated arrangement for electrochemically assisted injection in combination with capillary electrophoresis time-of-flight mass spectrometry. (United States)

    Palatzky, Peter; Matysik, Frank-Michael


    Electrochemically assisted injection (EAI) is an attractive injection concept for CE that enables the separation of neutral analytes via electrochemical generation of charged species during the injection process. A new semiautomated EAI configuration was developed and applied in conjunction with CE-MS (EAI-CE-MS). The EAI cell arrangement consists of an integrated buffer reservoir for CE separations and a compartment holding screen-printed electrodes. A drop of sample solution (50 μL) was sufficient to cover the three-electrode structures. A piezo motor provided a fast and precise capillary positioning over the screen-printed electrode assembly. Using ferrocene methanol as a model system, the EAI arrangement was characterized regarding coulometric efficiency, precision, and sensitivity of electrospray ionization-time-of-flight-MS. The formation of the cationic oxidation product of ferrocene methanol enhanced the sensitivity of CE-MS determination by two orders of magnitude and the electrochemically formed product showed a migration time corresponding to its individual electrophoretic mobility. Preliminary studies of EAI-CE-MS in the field of the analysis of nitroaromatic compounds were carried out. The formation of corresponding hydroxylamines and amines paved the way for selective and sensitive CE-MS determinations without the need of adding surfactants to the electrophoresis buffer.

  15. Analytical quality by design in the development of a cyclodextrin-modified capillary electrophoresis method for the assay of metformin and its related substances. (United States)

    Orlandini, Serena; Pasquini, Benedetta; Gotti, Roberto; Giuffrida, Alessandro; Paternostro, Ferdinando; Furlanetto, Sandra


    Quality by Design (QbD) is a new paradigm of quality to be applied to pharmaceutical products and processes, recently encouraged by International Conference on Harmonisation guidelines. In this paper QbD approach was applied to the development of a CE method for the simultaneous assay of metformin hydrochloride (MET) and its main impurities. QbD strategy was focused on electrophoretic process understanding, and the analytical method was thoroughly evaluated by applying risk assessment and chemometric tools. Method scouting allowed CD-CZE based on the addition of carboxymethyl-β-CD to Britton-Robinson acidic buffer to be chosen as operative mode. Seven critical process parameters (CPPs) were selected, related to capillary, injection, BGE and instrumental settings. The effect of the different levels of the CPPs on critical quality attributes (CQAs), e.g. critical resolution values and analysis time, was evaluated in a screening study. Response surface methodology led to draw contour plots and sweet spot plots. The definition of design space was accomplished by applying Monte-Carlo simulations, thus identifying by risk of failure maps a multivariate zone where the CQAs fulfilled the requirements with a selected probability. Finally, a control strategy was designed and the method was applied to a real sample of MET tablets.

  16. Capillary electrophoresis systems and methods (United States)

    Dorairaj, Rathissh; Keynton, Robert S.; Roussel, Thomas J.; Crain, Mark M.; Jackson, Douglas J.; Walsh, Kevin M.; Naber, John F.; Baldwin, Richard P.; Franco, Danielle B.


    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.

  17. Capillary electrophoresis in food authenticity. (United States)

    Kvasnicka, Frantisek


    Food authenticity is a term which simply refers to whether the food purchased by the consumer matches its description. False description can occur in many forms, from the undeclared addition of water or other cheaper materials, or the wrong declaration of the amount of a particular ingredient in the product, to making false statements about the source of ingredients i.e., their geographic, plant, or animal origin. The aim of this review is to summarize applications of capillary electrophoresis in food authentication.

  18. Capillary electrophoresis-mass spectrometry using noncovalently coated capillaries for the analysis of biopharmaceuticals. (United States)

    Haselberg, R; Brinks, V; Hawe, A; de Jong, G J; Somsen, G W


    In this work, the usefulness of capillary electrophoresis-electrospray ionization time-of-flight-mass spectrometry for the analysis of biopharmaceuticals was studied. Noncovalently bound capillary coatings consisting of Polybrene-poly(vinyl sulfonic acid) or Polybrene-dextran sulfate-Polybrene were used to minimize protein and peptide adsorption, and achieve good separation efficiencies. The potential of the capillary electrophoresis-mass spectrometry (CE-MS) system to characterize degradation products was investigated by analyzing samples of the drugs, recombinant human growth hormone (rhGH) and oxytocin, which had been subjected to prolonged storage, heat exposure, and/or different pH values. Modifications could be assigned based on accurate masses as obtained with time-of-flight-mass spectrometry (TOF-MS) and migration times with respect to the parent compound. For heat-exposed rhGH, oxidations, sulfonate formation, and deamidations were observed. Oxytocin showed strong deamidation (up to 40%) upon heat exposure at low pH, whereas at medium and high pH, mainly dimer (>10%) and trisulfide formation (6-7%) occurred. Recombinant human interferon-β-1a (rhIFN-β) was used to evaluate the capability of the CE-MS method to assess glycan heterogeneity of pharmaceutical proteins. Analysis of this N-glycosylated protein revealed a cluster of resolved peaks which appeared to be caused by at least ten glycoforms differing merely in sialic acid and hexose N-acetylhexosamine composition. Based on the relative peak area (assuming an equimolar response per glycoform), a quantitative profile could be derived with the disialytated biantennary glycoform as most abundant (52%). Such a profile may be useful for in-process and quality control of rhIFN-β batches. It is concluded that the separation power provided by combined capillary electrophoresis and TOF-MS allows discrimination of highly related protein species.

  19. Progression of Diabetic Capillary Occlusion: A Model.

    Directory of Open Access Journals (Sweden)

    Xiao Fu


    Full Text Available An explanatory computational model is developed of the contiguous areas of retinal capillary loss which play a large role in diabetic maculapathy and diabetic retinal neovascularization. Strictly random leukocyte mediated capillary occlusion cannot explain the occurrence of large contiguous areas of retinal ischemia. Therefore occlusion of an individual capillary must increase the probability of occlusion of surrounding capillaries. A retinal perifoveal vascular sector as well as a peripheral retinal capillary network and a deleted hexagonal capillary network are modelled using Compucell3D. The perifoveal modelling produces a pattern of spreading capillary loss with associated macular edema. In the peripheral network, spreading ischemia results from the progressive loss of the ladder capillaries which connect peripheral arterioles and venules. System blood flow was elevated in the macular model before a later reduction in flow in cases with progression of capillary occlusions. Simulations differing only in initial vascular network structures but with identical dynamics for oxygen, growth factors and vascular occlusions, replicate key clinical observations of ischemia and macular edema in the posterior pole and ischemia in the retinal periphery. The simulation results also seem consistent with quantitative data on macular blood flow and qualitative data on venous oxygenation. One computational model applied to distinct capillary networks in different retinal regions yielded results comparable to clinical observations in those regions.

  20. Performance Evaluation of Automated Passive Capillary Sampler for Estimating Water Drainage in the Vadose Zone (United States)

    Passive capillary samplers (PCAPs) are widely used to monitor, measure and sample drainage water under saturated and unsaturated soil conditions in the vadose zone. The objective of this study was to evaluate the performance and accuracy of automated passive capillary sampler for estimating drainage...

  1. Investigation of interaction between the drug and cell membrane by capillary electrophoresis

    Institute of Scientific and Technical Information of China (English)


    By introducing cell membrane into electrophoretic buffer as pseudo-stationary phase,a novel capillary electrophoresis method was established to explore the interaction between drugs and cell membrane,where the interaction between citalopram and rabbit red blood cell membrane was used as an example. A series of concentrations of cell membrane were suspended into the running buffer by peak-shift method. The binding constant of citalopram to rabbit red blood cell membrane of 0.977 g-1·L was obtained after treatment of Scatchard plot. This method could provide not only a new way for the investigation on the interactions between drugs and cell membrane,but also a new approach for high throughput screening of the drug membrane permeability,biological activity,and evaluating drugs in vivo.

  2. Development of a capillary electrophoresis method for the simultaneous determination of cephalosporins

    Directory of Open Access Journals (Sweden)

    Hancu Gabriel


    Full Text Available A rapid and simple capillary electrophoresis method has been developed for the simultaneous determination of six extensively used cephalosporin antibiotics (cefaclor, cefadroxil, cefalexin, cefuroxim, ceftazidim, ceftriaxon. The determination of cephalosporins was performed at a pH 6.8, using a 25 mM phospate - 25 mM borate mixed buffer, + 25 kV voltage at a temperature of 25 °C. We achieved a baseline separation in approximately 10 minutes. The separation resolution was increased by addition of an anionic surfactant, 50 mM sodium dodecyl sulfate, to the buffer solution. The proposed separation was evaluated on the basis of detection and quantification limits, effective electrophoretic mobility and relative standard deviation for migration times and peak areas.

  3. Capillary-inertial colloidal catapults upon drop coalescence (United States)

    Chavez, Roger L.; Liu, Fangjie; Feng, James J.; Chen, Chuan-Hua


    Surface energy released upon drop coalescence is known to power the self-propelled jumping of liquid droplets on superhydrophobic solid surfaces, and the jumping droplets can additionally carry colloidal payloads toward self-cleaning. Here, we show that drop coalescence on a spherical particle leads to self-propelled launching of the particle from virtually any solid surface. The main prerequisite is an intermediate wettability of the particle, such that the momentum from the capillary-inertial drop coalescence process can be transferred to the particle. By momentum conservation, the launching velocity of the particle-drop complex is proportional to the capillary-inertial velocity based on the drop radius and to the fraction of the liquid mass in the total mass. The capillary-inertial catapult is not only an alternative mechanism for removing colloidal contaminants, but also a useful model system for studying ballistospore launching.

  4. Crystal growth from the melt by capillary shaping techniques (United States)

    Ossipyan, Y. A.; Tatarchenko, V. A.

    A method based on the Lyapunov stability theory has been developed for studying the stability of crystallization by capillary shaping techniques (including Czochralski, Stepanov, EFG, Verneuil and floating zone methods). The preliminary results of the analysis of stability shows that the crystallization by capillary shaping technique under microgravitation conditions is more stable in some cases than under the action of gravitation. To get deeper into details of the capillary shaping technique under microgravitation conditions, we have carried out model experiments using two immiscible liquids of equal density and crystallization of sapphire in terrestrial conditions with small Bond number. The experiments on the copper crystallization were realized in the high-altitude rockets. Our experiments on indium crystallization carried out in the orbital space probe “Salyut” yielded cylindrical specimens.

  5. Three-Dimensional Reconstruction of Erythrocyte in the Capillary

    CERN Document Server

    Fan, Yifang; Li, Zhiyu; Lin, Wentao; Wei, Yuan; Zhong, Xing; Newman, Tony; Lv, Changsheng; Fan, Yuzhou


    The dynamic analysis of erythrocyte deformability is used as an important means for early diagnosis of blood diseases and blood rheology. Yet no effective method is available in terms of three-dimensional reconstruction of erythrocytes in a capillary. In this study, ultrathin serial sections of skeletal muscle tissue are obtained from the ultramicrotome, the tomographic images of an erythrocyte in a capillary are captured by the transmission electron microscope, and then a method to position and restore is devised to demonstrate the physiological relationship between two adjacent tomographic images of an erythrocyte. Both the modeling and the physical verification reveal that this method is effective, which means that it can be used to make three-dimensional reconstruction of an erythrocyte in a capillary. An example of reconstructed deformation of erythrocyte based on the serial ultrathin sections is shown at the end of this paper.

  6. Electrophoretic deposition of ZnO/alginate and ZnO-bioactive glass/alginate composite coatings for antimicrobial applications

    Energy Technology Data Exchange (ETDEWEB)

    Cordero-Arias, L.; Cabanas-Polo, S.; Goudouri, O.M. [Institute of Biomaterials, Department of Materials Science and Engineering, University of Erlangen-Nuremberg, Cauerstrasse 6, D-91058 Erlangen (Germany); Misra, S.K. [Materials Science and Engineering, Indian Institute of Technology Gandhinagar, Ahmedabad 382424 (India); Gilabert, J. [Institute of Ceramics Materials (ITC), University Jaume I, Avenida Vicent SosBaynat, 12006 Castellon (Spain); Valsami-Jones, E. [School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Sanchez, E. [Institute of Ceramics Materials (ITC), University Jaume I, Avenida Vicent SosBaynat, 12006 Castellon (Spain); Virtanen, S. [Institute for Surface Science and Corrosion (LKO, WW4), Department of Materials Science and Engineering, University of Erlangen-Nuremberg, Martensstrasse 7, D-91058 Erlangen (Germany); Boccaccini, A.R., E-mail: [Institute of Biomaterials, Department of Materials Science and Engineering, University of Erlangen-Nuremberg, Cauerstrasse 6, D-91058 Erlangen (Germany)


    Two organic/inorganic composite coatings based on alginate, as organic matrix, and zinc oxide nanoparticles (n-ZnO) with and without bioactive glass (BG), as inorganic components, intended for biomedical applications, were developed by electrophoretic deposition (EPD). Different n-ZnO (1–10 g/L) and BG (1–1.5 g/L) contents were studied for a fixed alginate concentration (2 g/L). The presence of n-ZnO was confirmed to impart antibacterial properties to the coatings against gram-negative bacteria Escherichia coli, while the BG induced the formation of hydroxyapatite on coating surfaces thereby imparting bioactivity, making the coating suitable for bone replacement applications. Coating composition was analyzed by thermogravimetric analysis (TG), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDS) analyses. Scanning electron microscopy (SEM) was employed to study both the surface and the cross section morphology of the coatings. Polarization curves of the coated substrates made in cell culture media at 37 °C confirmed the corrosion protection function of the novel organic/inorganic composite coatings. - Highlights: • Organic–inorganic nanocomposite coatings fabricated by electrophoretic deposition • nZnO and bioactive glass containing alginate coatings exhibit antibacterial effect. • Bioactive character and anticorrosion function of coatings demonstrated.

  7. Atomic-scale friction : thermal effects and capillary condensation

    NARCIS (Netherlands)

    Jinesh, Kochupurackal Balakrishna Pillai


    This work entitled as "Atomic-scale friction: thermal effects and capillary condensation" is a study on the fundamental aspects of the origin of friction from the atomic-scale. We study two realistic aspects of atomic-scale friction, namely the effect of temperature and the effect of relative humidi

  8. Capillary surface discontinuities above reentrant corners (United States)

    Korevaar, H. J.


    A particular configuration of a vertical capillary tube for which S is the equilibrium interface between two fluids in the presence of a downward pointing gravitational field was investigated. S is the graph a function u whose domain is the (horizontal) cross section gamma of the tube. The mean curvature of S is proportional to its height above a fixed reference plane and lambda is a prescribed constant and may be taken between zero and pi/2. Domains gamma for which us is a bounded function but does not extend continuously to d gamma are sought. Simple domains are found and the behavior of u in those domains is studied. An important comparison principle that has been used in the literature to derive many of the results in capillarity is reviewed. It allows one to deduce the approximate shape of a capillary surface by constructing comparison surfaces with mean curvature and contact angle close to those of the (unknown) solution surface. In the context of nonparametric problems the comparison principle leads to height estimates above and below for the function u. An example from the literature where these height estimates have been used successfully is described. The promised domains for which the bounded u does not extend continuously to the boundary are constructed. The point on the boundary at which u has a jump discontinuity will be the vertext of a re-entrant corner having any interior angle theta pi. Using the comparison principle the behavior of u near this point is studied.

  9. Synthesis of functionally graded materials via electrophoretic deposition and sintering (United States)

    Wang, Xuan

    In this research, both the experiments and the modeling aspects of the net-shape fabrication of Functionally Graded Materials (FGM) by Electrophoretic Deposition (EPD) and consecutive sintering have been investigated. In order to obtain FGMs with desired final shape and properties, the issues regarding the shape evolution during sintering, the optimization of initial properties and composition profiles, and the fabrication of green components by EPD have been analyzed. In order to fabricate FGMs by the proposed technological sequence (EPD with the following sintering), the initial shape has to be optimized prior to sintering. In this research, the formulations to simulate sintering of an FGM were developed based on the continuum theory of sintering. A finite element sintering-modeling subroutine has been created and linked to the commercial finite element package ABAQUS. The shape changes of FGM disks during sintering were simulated. In order to obtain the desired final shape after sintering, an inverse modeling methodology was developed to optimize the initial shape. In order to fabricate the optimized initial shape of a green FGM specimen determined by the inverse continuum modeling of sintering, EPD of a number of FGMs was investigated. The FGM green specimens made of Al2O 3 and ZrO2 with the initial shape predicted by the inverse modeling, were deposited using self-designed equipments. The acetone-based suspension with n-butylamine as a particle-charging additive was used. The comparison of the shape between the sintered and the green FGM indicated that the developed experimental-theoretical methodology provided a reliable solution for near net shaping of complex 3-D FGM components. Other applications of EPD, such as in electronic packaging materials and zeolites, were also investigated. In order to fabricate functionally graded materials based on aligned porous structures, unidirectional freezing followed by freeze-drying and sintering has been investigated

  10. The role of the rheological properties of non-newtonian fluids in controlling dispersive mixing in a batch electrophoretic cell with Joule heating

    Directory of Open Access Journals (Sweden)

    M.A. Bosse


    Full Text Available The problem of the effect of Joule heating generation on the hydrodynamic profile and the solute transport found in electrophoretic devices is addressed in this article. The research is focused on the following two problems: The first one is centered around the effect of Joule heating on the hydrodynamic velocity profile and it is referred to as "the carrier fluid problem." The other one is related to the effect of Joule heating on the solute transport inside electrophoretic cells and it is referred to as "the solute problem". The hydrodynamic aspects were studied first to yield the velocity profiles required for analysis of the solute transport problem. The velocity profile obtained in this study is analytical and the results are valid for non-Newtonian fluids carriers. To this end, the power-law model was used to study the effect of the rheology of the material in conjunction with the effect of Joule heating generation inside batch electrophoretic devices. This aspect of the research was then effectively used to study the effect of Joule heating generation on the motion of solutes (such as macromolecules under the influence of non-Newtonian carriers. This aspect of the study was performed using an area-averaging approach that yielded analytical results for the effective diffusivity of the device.

  11. Analysis of phenolic type antioxidants; Capillary gas chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Chopra, S.K. (Indian Inst. of Petroleum, Dehradun (India)); Kapoor, V.B. (Indian Inst. of Petroleum, Dehradun (India)); Vishnoi, S.C. (Indian Inst. of Petroleum, Dehradun (India)); Bhagat, S.D. (Indian Inst. of Petroleum, Dehradun (India))


    A simple gas chromatographic (GC) procedure has been developed to estimate the individual alkylated phenols used as antioxidants to improve the shelf life of fuels and lubricants. Preparative gas chromatography was applied for separation and collection in sufficient quantity of the isomers of tertiary butyl, octyl and dodecyl phenols prepared by catalytic alkylation of phenol with isobutylene or its oligomers. The separated fractions were characterised by Infra-red spectrometry (IR) and paper chromatography. Out of several GC columns studies, a high resolution capillary column of 100% Methyl, Silicone gum (SE-30) as stationary phase gave best results. Data generated on various packed and capillary columns are in good agreement. (orig.)

  12. Simple model of capillary condensation in cylindrical pores (United States)

    Szybisz, Leszek; Urrutia, Ignacio


    A simple model based on an approximation of the dropletlike model is formulated for studying adsorption of fluids into cylindrical pores. This model yields a nearly universal description of capillary condensation transitions for noble gases confined by alkali metals. The system's thermodynamical behavior is predicted from the values of two dimensionless parameters: D* (the reduced asymptotic strength of the fluid-adsorber interaction, a function of temperature) and R* (the reduced radius of the pore). The phenomenon of hysteresis inherently related to capillary condensation is discussed. The connection to a previously proposed universality for cylindrical pores is also established.

  13. Vorticity and Capillaries at the Surface of a Jet

    CERN Document Server

    Andre, Matthieu A


    Shear layer instability at the free surface of a water jet is studied. The accompanying video shows experimental data recorded using measurement methods such as Planar Laser Induced Fluorescence (PLIF) and Particle Image Velocity (PIV). These results reveal the mechanisms leading to the formation of capillary waves on the surface due to the roll-up of the shear layer. These capillary waves eventually collide to each other, injecting vorticity in the bulk of the flow. Shear layer and injected vorticity interact to form a counter rotating vortex pair that moves down to the flow.

  14. Mapping molecular adhesion sites inside SMIL coated capillaries using atomic force microscopy recognition imaging

    Energy Technology Data Exchange (ETDEWEB)

    Leitner, Michael [Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz (Austria); Stock, Lorenz G. [Division of Chemistry and Bioanalytics, Department of Molecular Biology, University Salzburg, Hellbrunnerstrasse 34, 5020 Salzburg (Austria); Christian Doppler Laboratory for Innovative Tools for the Characterization of Biosimilars, University Salzburg, Hellbrunnerstrasse 34, 5020 Salzburg (Austria); Traxler, Lukas [Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz (Austria); Leclercq, Laurent [Institut des Biomolécules Max Mousseron (IBMM, UMR 5247, CNRS, Université de Montpellier, Ecole Nationale Supérieure de Chimie de Montpellier), Place Eugène Bataillon, CC 1706, 34095 Montpellier (France); Bonazza, Klaus; Friedbacher, Gernot [Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9/164, 1060 Vienna (Austria); Cottet, Hervé [Institut des Biomolécules Max Mousseron (IBMM, UMR 5247, CNRS, Université de Montpellier, Ecole Nationale Supérieure de Chimie de Montpellier), Place Eugène Bataillon, CC 1706, 34095 Montpellier (France); Stutz, Hanno [Division of Chemistry and Bioanalytics, Department of Molecular Biology, University Salzburg, Hellbrunnerstrasse 34, 5020 Salzburg (Austria); Christian Doppler Laboratory for Innovative Tools for the Characterization of Biosimilars, University Salzburg, Hellbrunnerstrasse 34, 5020 Salzburg (Austria); Ebner, Andreas, E-mail: [Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz (Austria)


    Capillary zone electrophoresis (CZE) is a powerful analytical technique for fast and efficient separation of different analytes ranging from small inorganic ions to large proteins. However electrophoretic resolution significantly depends on the coating of the inner capillary surface. High technical efforts like Successive Multiple Ionic Polymer Layer (SMIL) generation have been taken to develop stable coatings with switchable surface charges fulfilling the requirements needed for optimal separation. Although the performance can be easily proven in normalized test runs, characterization of the coating itself remains challenging. Atomic force microscopy (AFM) allows for topographical investigation of biological and analytical relevant surfaces with nanometer resolution and yields information about the surface roughness and homogeneity. Upgrading the scanning tip to a molecular biosensor by adhesive molecules (like partly inverted charged molecules) allows for performing topography and recognition imaging (TREC). As a result, simultaneously acquired sample topography and adhesion maps can be recorded. We optimized this technique for electrophoresis capillaries and investigated the charge distribution of differently composed and treated SMIL coatings. By using the positively charged protein avidin as a single molecule sensor, we compared these SMIL coatings with respect to negative charges, resulting in adhesion maps with nanometer resolution. The capability of TREC as a functional investigation technique at the nanoscale was successfully demonstrated. - Highlights: • SMIL coating allows generation of homogeneous ultra-flat surfaces. • Molecular electrostatic adhesion forces can be determined in the inner wall of CZE capillary with picoNewton accuracy. • Topographical images and simultaneously acquired adhesion maps yield morphological and chemical information at the nanoscale.

  15. A DC electrophoresis method for determining electrophoretic mobility through the pressure driven negation of electro osmosis (United States)

    Karam, Pascal; Pennathur, Sumita


    Characterization of the electrophoretic mobility and zeta potential of micro and nanoparticles is important for assessing properties such as stability, charge and size. In electrophoretic techniques for such characterization, the bulk fluid motion due to the interaction between the fluid and the charged surface must be accounted for. Unlike current industrial systems which rely on DLS and oscillating potentials to mitigate electroosmotic flow (EOF), we propose a simple alternative electrophoretic method for optically determining electrophoretic mobility using a DC electric fields. Specifically, we create a system where an adverse pressure gradient counters EOF, and design the geometry of the channel so that the flow profile of the pressure driven flow matches that of the EOF in large regions of the channel (ie. where we observe particle flow). Our specific COMSOL-optimized geometry is two large cross sectional areas adjacent to a central, high aspect ratio channel. We show that this effectively removes EOF from a large region of the channel and allows for the accurate optical characterization of electrophoretic particle mobility, no matter the wall charge or particle size.

  16. Controlled method of reducing electrophoretic mobility of macromolecules, particles, or cells (United States)

    Vanalstine, James M. (Inventor)


    A method of reducing electrophoretic mobility of macromolecules, particles, cells, and other substances is provided which comprises interacting in a conventional electrophoretic separating procedure, the substances with a polymer-linked affinity compound comprised of a hydrophilic neutral polymer such as polyethylene glycol bound to a second component such as a hydrophobic compound, an immunocompound such as an antibody or antibody active fragment, or a ligand such as a hormone, drug, antigen, or a hapten. The reduction of electrophoretic mobility achieved is directly proportional to the concentration of the polymer-linked affinity compound employed, and such reduction can comprise up to 100 percent for particular particles and cells. The present invention is advantageous in that electrophoretic separation can now be achieved for substances whose native surface charge structure had prevented them from being separated by normal electrophoretic means. Depending on the affinity component utilized, separation can be achieved on the basis of the specific/irreversible, specific/reversible, semi-specific/reversible, relatively nonspecific/reversible, or relatively nonspecific/irreversible ligand-substance interactions.

  17. Capillary pumped loop body heat exchanger (United States)

    Swanson, Theodore D. (Inventor); Wren, deceased, Paul (Inventor)


    A capillary pumped loop for transferring heat from one body part to another body part, the capillary pumped loop comprising a capillary evaporator for vaporizing a liquid refrigerant by absorbing heat from a warm body part, a condenser for turning a vaporized refrigerant into a liquid by transferring heat from the vaporized liquid to a cool body part, a first tube section connecting an output port of the capillary evaporator to an input of the condenser, and a second tube section connecting an output of the condenser to an input port of the capillary evaporator. A wick may be provided within the condenser. A pump may be provided between the second tube section and the input port of the capillary evaporator. Additionally, an esternal heat source or heat sink may be utilized.

  18. Electrophoretic method for the determination of the proportion of gamma-aminobutyric acid in a mixture of labeled neurotransmitter and its catabolites

    Energy Technology Data Exchange (ETDEWEB)

    Cupello, A.; Rapallino, M.V.; Besio, G.; Mainardi, P.


    An electrophoretic method for the separation of gamma-aminobutyric acid (GABA) from its metabolites after GABA-transaminase attack is presented. The method is based on the fact that at neutral pH GABA has no net electrical charge, whereas its major metabolites, succinic acid and Krebs cycle intermediates, are negatively charged. The method appears to be especially suitable for evaluation of true-labeled neurotransmitter within the radioactivity which is found in synaptosomes after labeled GABA-uptake studies.

  19. Measurement of Liquid Viscosities in Tapered or Parabolic Capillaries. (United States)

    Ershov; Zorin; Starov


    The possibility of using tapered or parabolic capillaries for measurement of liquid viscosities is investigated both experimentally and theoretically. It is demonstrated that even small deviations in capillary radius from a constant value may substantially affect measurement results. Equations are derived which allow correct analysis of the measurement results in tapered or parabolic capillaries. The following cases are analyzed: a water imbibition into a tapered or parabolic capillary and displacement of one liquid by another immiscible liquid in tapered or parabolic capillaries. Two possibilities are considered: (a) the narrow end of the capillary as capillary inlet and (b) the wide end of the capillary as capillary inlet. Copyright 1999 Academic Press.

  20. Solid oxide fuel cell electrolytes produced via very low pressure suspension plasma spray and electrophoretic deposition (United States)

    Fleetwood, James D.

    Solid oxide fuel cells (SOFCs) are a promising element of comprehensive energy policies due to their direct mechanism for converting the oxidization of fuel, such as hydrogen, into electrical energy. Both very low pressure plasma spray and electrophoretic deposition allow working with high melting temperature SOFC suspension based feedstock on complex surfaces, such as in non-planar SOFC designs. Dense, thin electrolytes of ideal composition for SOFCs can be fabricated with each of these processes, while compositional control is achieved with dissolved dopant compounds that are incorporated into the coating during deposition. In the work reported, sub-micron 8 mole % Y2O3-ZrO2 (YSZ) and gadolinia-doped ceria (GDC), powders, including those in suspension with scandium-nitrate dopants, were deposited on NiO-YSZ anodes, via very low pressure suspension plasma spray (VLPSPS) at Sandia National Laboratories' Thermal Spray Research Laboratory and electrophoretic deposition (EPD) at Purdue University. Plasma spray was carried out in a chamber held at 320 - 1300 Pa, with the plasma composed of argon, hydrogen, and helium. EPD was characterized utilizing constant current deposition at 10 mm electrode separation, with deposits sintered from 1300 -- 1500 °C for 2 hours. The role of suspension constituents in EPD was analyzed based on a parametric study of powder loading, powder specific surface area, polyvinyl butyral (PVB) content, polyethyleneimine (PEI) content, and acetic acid content. Increasing PVB content and reduction of particle specific surface area were found to eliminate the formation of cracks when drying. PEI and acetic acid content were used to control suspension stability and the adhesion of deposits. Additionally, EPD was used to fabricate YSZ/GDC bilayer electrolyte systems. The resultant YSZ electrolytes were 2-27 microns thick and up to 97% dense. Electrolyte performance as part of a SOFC system with screen printed LSCF cathodes was evaluated with peak

  1. Ultrastructural, autoradiographic and electrophoretic examinations of Chara tomentosa spermiogenesis

    Directory of Open Access Journals (Sweden)

    Maria Kwiatkowska


    Full Text Available Ultrastructure of a spermatid nucleus changes many times during spermiogenesis. Condensed chromatin forms irregular clusters during phases I-II, a continuous ring adjacent to a nuclear envelope during phases III-V and a network occupying the whole nucleus during phase VI. In advanced spermiogenesis dense chromatin disappears and short randomly positioned fibrils arise, then long parallel ones are found (phase VIII which during phase IX form a lamellar structure. In mature spermatozoids (phase X chromatin becomes extremely condensed. 3H-arginine and 3H-lysine incorporation into spermatids during 2-min incubation is intensive during phases IN, decreases during phases VI, VII and becomes very low during phases VIII-IX. Capillary electrophoresis has shown that during Chara tomentosa spermiogenesis replacement of histones with basic proteins whose mobility is comparable to that of salmon protamines takes place. At the beginning of spermiogenesis core and linker histones are found in spermatids. During early spermiogenesis protamine-like proteins appear and their amount increases in late spermiogenesis when core histones are still present. In mature spermatozoids only protamine-like proteins represented by 3 fractions: 9.1 kDa, 9.6 kDa, 11.2 kDa are found. Disappearance of linker histones following their modification precedes disappearance of core histones. The results indicate that dynamic rearrangement of chromatin ultrastructure and aminoacid incorporation rate during spermiogenesis are reflected in basic nuclear protein changes.

  2. A New Conductivity Detector for Capillary Electrophoresis

    Institute of Scientific and Technical Information of China (English)


    A new conductivity detector for capillary electrophoresis consisting of an electrochemical cell and a conductive meter was developed. In the cell, the microelectrode and capillary were inserted through the cell wall and fixed by screws and sealing ring, the ends of microelectrode and capillary were located by a guide with two cross holes. LOD for K+ was 1.5×10-5 mol/L.

  3. Vesicle dynamics in shear and capillary flows (United States)

    Noguchi, Hiroshi; Gompper, Gerhard


    The deformation of vesicles in flow is studied by a mesoscopic simulation technique, which combines multi-particle collision dynamics for the solvent with a dynamically triangulated surface model for the membrane. Shape transitions are investigated both in simple shear flows and in cylindrical capillary flows. We focus on reduced volumes, where the discocyte shape of fluid vesicles is stable, and the prolate shape is metastable. In simple shear flow at low membrane viscosity, the shear induces a transformation from discocyte to prolate with increasing shear rate, while at high membrane viscosity, the shear induces a transformation from prolate to discocyte, or tumbling motion accompanied by oscillations between these two morphologies. In capillary flow, at small flow velocities the symmetry axis of the discocyte is found not to be oriented perpendicular to the cylinder axis. With increasing flow velocity, a transition to a prolate shape occurs for fluid vesicles, while vesicles with shear-elastic membranes (like red blood cells) transform into a coaxial parachute-like shape.

  4. Observations of gravity-capillary lump interactions

    CERN Document Server

    Masnadi, Naeem


    In this experimental study, we investigate the interaction of gravity-capillary solitary waves generated by two surface pressure sources moving side by side at constant speed. The nonlinear response of a water surface to a single source moving at a speed just below the minimum phase speed of linear gravity-capillary waves in deep water ($c_{min}\\approx23$ cm s$^{-1}$) consists of periodic generation of pairs of three-dimensional solitary waves (or lumps) in a V-shaped pattern downstream of the source. In the reference frame of the laboratory, these unsteady lumps propagate in a direction oblique to the motion of the source. In the present experiments, the strength of the two sources is adjusted to produce nearly identical responses and the free surface deformations are visualized using photography-based techniques. The first lumps generated by the two sources move in intersecting directions that make a half angle of approximately 15 degrees and collide in the center-plane between the sources. A steep depressi...

  5. Capillary wrinkling of thin bilayer polymeric sheets (United States)

    Chang, Jooyoung; Menon, Narayanan; Russell, Thomas

    We have investigated capillary force induced wrinkling on a floated polymeric bilayer thin sheet. The origin of the wrinkle pattern is compressional hoop stress caused by the capillary force of a water droplet placed on the floated polymeric thin sheet afore investigated. Herein, we study the effect of the differences of surface energy arising from the hydrophobicity of Polystyrene (PS Mw: 97 K, Contact Angle: 88 º) and the hydrophilicity of Poly(methylmethacrylate) (PMMA Mw: 99K, Contact Angle: 68 º) on two sides of a bilayer film. We measure the number and the length of the wrinkles by broadly varying the range of thicknesses of top (9 nm to 550 nm) and bottom layer (25 nm to 330 nm). At the same, there is only a small contrast in mechanical properties of the two layers (PS E = 3.4 GPa, and PMMA E = 3 GPa). The number of the wrinkles is not strongly affected by the composition (PS(Top)/PMMA(Bottom) or PMMA(Top)/PS(Bottom)) and the thickness of each and overall bilayer system. However, the length of the wrinkle is governed by the contact angle of the drop on the top layer of bilayer system. We also compare this to the wrinkle pattern obtained in monolayer systems over a wide range of thickness from PS and PMMA (7 nm to 1 μm). W.M. Keck Foundation.

  6. Investigation into the suitability of capillary tubes for microcrystalline testing. (United States)

    Elie, Leonie E; Baron, Mark G; Croxton, Ruth S; Elie, Mathieu P


    A comparison between microcrystalline tests performed on microscope slides and flat capillary tubes with inner diameters ranging from 0.1 to 0.7 mm was carried out to explore the appropriateness of tubes for rapid testing of suspected drugs of abuse in the laboratory as well as in the field. Tests for mephedrone, cocaine, and phencyclidine were chosen as examples to investigate the handling of the capillary tubes, the influence on crystal habit, size, and the effects on the limit of detection. Image stacking software was used to increase the depth of field of micrographs taken from developed microcrystals greatly enhancing the interpretability even months after carrying out the microcrystalline test. Additionally, the potential of seeding capillary tubes with a reagent was studied. Pre-treatment of tubes would allow microcrystalline tests to be carried out quicker and anywhere without the necessity of taking along expensive and hazardous reagents. The sealing of capillary tubes containing developed microcrystalline tests in order to preserve results for a long period of time was successfully done by applying paraffin wax to the open ends. Finally, it was concluded that capillary tubes are suitable vessels for performing microcrystalline tests. The increased portability of the improved set-up allows tests to be safely executed outside laboratories without impairing the quality of the result. Findings were applied to six legal high samples purchased online between May and August 2011. The active ingredients like MDAI as well as cutting agents like caffeine were successfully identified using the microcrystalline test technique in capillary tubes.

  7. Molecular transport through capillaries made with atomic-scale precision (United States)

    Radha, B.; Esfandiar, A.; Wang, F. C.; Rooney, A. P.; Gopinadhan, K.; Keerthi, A.; Mishchenko, A.; Janardanan, A.; Blake, P.; Fumagalli, L.; Lozada-Hidalgo, M.; Garaj, S.; Haigh, S. J.; Grigorieva, I. V.; Wu, H. A.; Geim, A. K.


    Nanometre-scale pores and capillaries have long been studied because of their importance in many natural phenomena and their use in numerous applications. A more recent development is the ability to fabricate artificial capillaries with nanometre dimensions, which has enabled new research on molecular transport and led to the emergence of nanofluidics. But surface roughness in particular makes it challenging to produce capillaries with precisely controlled dimensions at this spatial scale. Here we report the fabrication of narrow and smooth capillaries through van der Waals assembly, with atomically flat sheets at the top and bottom separated by spacers made of two-dimensional crystals with a precisely controlled number of layers. We use graphene and its multilayers as archetypal two-dimensional materials to demonstrate this technology, which produces structures that can be viewed as if individual atomic planes had been removed from a bulk crystal to leave behind flat voids of a height chosen with atomic-scale precision. Water transport through the channels, ranging in height from one to several dozen atomic planes, is characterized by unexpectedly fast flow (up to 1 metre per second) that we attribute to high capillary pressures (about 1,000 bar) and large slip lengths. For channels that accommodate only a few layers of water, the flow exhibits a marked enhancement that we associate with an increased structural order in nanoconfined water. Our work opens up an avenue to making capillaries and cavities with sizes tunable to ångström precision, and with permeation properties further controlled through a wide choice of atomically flat materials available for channel walls.

  8. Fabrication of thin electrolyte film by electrophoretic deposition for intermediate-temperature solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Lankin, M.; Karan, K. [Royal Military Coll. of Canada, Kingston, ON (Canada). Fuel Cell Research Centre


    Stainless steel interconnects are suitable for use in intermediate temperature solid oxide fuel cells (ITSOFCs) operating at 500-700 degrees C. This can greatly reduce the cost of materials. However, lower temperatures lead to higher ohmic losses in the electrolyte. These losses can be reduced by making SOFCs with thin electrolyte layers. Conventional methods for thin-film fabrication such as electro-vapour deposition or plasma spraying are expensive techniques. An alternative method is electrophoretic deposition (EPD), which is less costly and which very rapidly produces uniform electrolyte layers in the order of 10-40 {mu}m. In this study, EPD was used to make thin gadolina-doped ceria (GDC) electrolytes on copper-GDC anodes for use in ITSOFCs fuelled by biofuels. Experimental studies thus far have shown how to optimize the parameters influencing the EPD process. Scanning electron microscope analysis has shown that electrolyte layers of 10 {mu}m thickness, uniform thickness and moderate density are produced by EPD. This paper described the development of a single-cell SOFC based on the EPD process, and discussed the progress to date, on characterizing thin film electrolytes.

  9. Elaboration of nanostructured biointerfaces with tunable degree of coverage by protein nanotubes using electrophoretic deposition. (United States)

    Kalaskar, Deepak M; Poleunis, Claude; Dupont-Gillain, Christine; Demoustier-Champagne, Sophie


    This study shows that electrophoretic deposition (EPD) is a fast and efficient technique for producing protein nanotube-based biointerfaces. Well-shaped collagen-based nanotubes of controlled dimensions are synthesized by a template method combined with the layer-by-layer (LbL) assembly technique. Separation of nanotubes from the template material and collection of nanotubes on ITO glass carried out by EPD leads to a fairly homogeneous distribution of protein nanotubes at the support surface. Biointerfaces with different and tunable densities of protein nanotubes are obtained by changing either the applied voltage, solution concentration of nanotubes, or deposition time. Moreover, it is proved that the collected nanotubes are template-free and keep their biofunctional outermost layer after EPD. A preliminary study of the behavior of preosteoblasts cells with the elaborated biointerfaces indicates a specific interaction of cells with the nanotubes through filopodia. This contribution paves the way to the easy preparation of a large variety of useful nanostructured collagen and other protein-based interfaces for controlling cell-surface interactions in diverse biomaterials applications.

  10. Microscale capillary wave turbulence excited by high frequency vibration. (United States)

    Blamey, Jeremy; Yeo, Leslie Y; Friend, James R


    Low frequency (O(10 Hz-10 kHz)) vibration excitation of capillary waves has been extensively studied for nearly two centuries. Such waves appear at the excitation frequency or at rational multiples of the excitation frequency through nonlinear coupling as a result of the finite displacement of the wave, most often at one-half the excitation frequency in so-called Faraday waves and twice this frequency in superharmonic waves. Less understood, however, are the dynamics of capillary waves driven by high-frequency vibration (>O(100 kHz)) and small interface length scales, an arrangement ideal for a broad variety of applications, from nebulizers for pulmonary drug delivery to complex nanoparticle synthesis. In the few studies conducted to date, a marked departure from the predictions of classical Faraday wave theory has been shown, with the appearance of broadband capillary wave generation from 100 Hz to the excitation frequency and beyond, without a clear explanation. We show that weak wave turbulence is the dominant mechanism in the behavior of the system, as evident from wave height frequency spectra that closely follow the Rayleigh-Jeans spectral response η ≈ ω(-17/12) as a consequence of a period-halving, weakly turbulent cascade that appears within a 1 mm water drop whether driven by thickness-mode or surface acoustic Rayleigh wave excitation. However, such a cascade is one-way, from low to high frequencies. The mechanism of exciting the cascade with high-frequency acoustic waves is an acoustic streaming-driven turbulent jet in the fluid bulk, driving the fundamental capillary wave resonance through the well-known coupling between bulk flow and surface waves. Unlike capillary waves, turbulent acoustic streaming can exhibit subharmonic cascades from high to low frequencies; here it appears from the excitation frequency all the way to the fundamental modes of the capillary wave at some four orders of magnitude in frequency less than the excitation frequency

  11. Slope wavenumber spectrum models of capillary and capillary-gravity waves

    Institute of Scientific and Technical Information of China (English)

    贾永君; 张杰; 王岩峰


    Capillary and capillary-gravity waves possess a random character, and the slope wavenumber spectra of them can be used to represent mean distributions of wave energy with respect to spatial scale of variability. But simple and practical models of the slope wavenumber spectra have not been put forward so far. In this article, we address the accurate definition of the slope wavenumber spectra of water surface capillary and capillary-gravity waves. By combining the existing slope wavenumber models and using th...

  12. A novel bisulfite-microfluidic temperature gradient capillary electrophoresis platform for highly sensitive detection of gene promoter methylation. (United States)

    Zhang, Huidan; Shan, Lianfeng; Wang, Xiaonan; Ma, Qian; Fang, Jin


    The hypermethylated tumor suppressor gene promoters are widely recognized as promising markers for cancer screening and ideal targets for cancer therapy, however, a major obstacle in their clinical study is highly sensitive screening. To address this limitation, we developed a novel bisulfite-microfluidic temperature gradient capillary electrophoresis (bisulfite-μTGCE) platform for gene methylation analysis by combining bisulfite treatment and slantwise radiative heating system-based μTGCE. Bisulfite-treated genomic DNA (gDNA) was amplified with universal primers for both methylated and unmethylated sequences, and introduced into glass microfluidic chip to perform electrophorectic separation under a continuous temperature gradient based on the formation of heteroduplexes. Eight CDKN2A promoter model fragments with different number and location of methylation sites were prepared and successfully analyzed according to their electrophoretic peak patterns, with high stability, picoliter-scale sample consumption, and significantly increased detection speed. The bisulfite-μTGCE could detect methylated gDNA with a detection limit of 7.5pg, and could distinguish as low as 0.1% methylation level in CDKN2A in an unmethylated background. Detection of seven colorectal cancer (CRC) cell lines with known and unknown methylation statuses of CDKN2A promoter and 20 tumor tissues derived from CRC patients demonstrated the capability of detecting hypermethylation in real-world samples. The wider adaptation of this platform was further supported by the detection of the CDKN2A and MLH1 promoters' methylation statuses in combination. This highly sensitive, fast, and low-consumption platform for methylation detection shows great potential for future clinical applications.

  13. Investigation of pressure drop in capillary tube for mixed refrigerant Joule-Thomson cryocooler

    Energy Technology Data Exchange (ETDEWEB)

    Ardhapurkar, P. M. [Mechanical Engineering Department, Indian Institute of Technology Bombay, Mumbai, MS 400 076 India and S. S. G. M. College of Engineering Shegaon, MS 444 203 (India); Sridharan, Arunkumar; Atrey, M. D. [Mechanical Engineering Department, Indian Institute of Technology Bombay, Mumbai, MS 400 076 (India)


    A capillary tube is commonly used in small capacity refrigeration and air-conditioning systems. It is also a preferred expansion device in mixed refrigerant Joule-Thomson (MR J-T) cryocoolers, since it is inexpensive and simple in configuration. However, the flow inside a capillary tube is complex, since flashing process that occurs in case of refrigeration and air-conditioning systems is metastable. A mixture of refrigerants such as nitrogen, methane, ethane, propane and iso-butane expands below its inversion temperature in the capillary tube of MR J-T cryocooler and reaches cryogenic temperature. The mass flow rate of refrigerant mixture circulating through capillary tube depends on the pressure difference across it. There are many empirical correlations which predict pressure drop across the capillary tube. However, they have not been tested for refrigerant mixtures and for operating conditions of the cryocooler. The present paper assesses the existing empirical correlations for predicting overall pressure drop across the capillary tube for the MR J-T cryocooler. The empirical correlations refer to homogeneous as well as separated flow models. Experiments are carried out to measure the overall pressure drop across the capillary tube for the cooler. Three different compositions of refrigerant mixture are used to study the pressure drop variations. The predicted overall pressure drop across the capillary tube is compared with the experimentally obtained value. The predictions obtained using homogeneous model show better match with the experimental results compared to separated flow models.

  14. Recent advances in the preparation and application of monolithic capillary columns in separation science

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Tingting; Yang, Xi; Xu, Yujing [Department of Analytical Chemistry, China Pharmaceutical University, Nanjing, 210009 (China); Key Laboratory of Drug Quality Control and Pharmacovigilance, Ministry of Education, Nanjing, 210009 (China); Ji, Yibing, E-mail: [Department of Analytical Chemistry, China Pharmaceutical University, Nanjing, 210009 (China); Key Laboratory of Drug Quality Control and Pharmacovigilance, Ministry of Education, Nanjing, 210009 (China)


    Novel column technologies involving various materials and efficient reactions have been investigated for the fabrication of monolithic capillary columns in the field of analytical chemistry. In addition to the development of these miniaturized systems, a variety of microscale separation applications have achieved noteworthy results, providing a stepping stone for new types of chromatographic columns with improved efficiency and selectivity. Three novel strategies for the preparation of capillary monoliths, including ionic liquid-based approaches, nanoparticle-based approaches and “click chemistry”, are highlighted in this review. Furthermore, we present the employment of state-of-the-art capillary monolithic stationary phases for enantioseparation, solid-phase microextraction, mixed-mode separation and immobilized enzyme reactors. The review concludes with recommendations for future studies and improvements in this field of research. - Highlights: • Preparation of novel monolithic capillary columns have shown powerful potential in analytical chemistry field. • Various materials including ionic liquids and nanoparticles involved into capillary monolithic micro-devices are concluded. • Click chemistry strategy applied for preparing monolithic capillary columns is reviewed. • Recent strategies utilized in constructing different capillary monoliths for enantiomeric separation are summarized. • Advancement of capillary monoliths for complex samples analysis is comprehensively described.

  15. Capillary electrophoresis theory and practice

    CERN Document Server

    Grossman, Paul D


    This book is designed to be a practical guide, used by wide audience, including those new to CE, those more experienced, routine users, those interested in technology development, and those involved with applications research. References have been emphasized to allow the reader to explore the detailed specifics and theoretical foundations.This book draws together the rapidly evolving, diverse, and multidisciplinary subject of capillary electrophoresis (CE). It is designed as a practical guide to be used by a wide audience, including those new to CE as well as more experienced users. T

  16. Electromigration dispersion in Capillary Electrophoresis

    CERN Document Server

    Chen, Zhen; 10.1007/s11538-011-9708-7


    In a previous paper (S. Ghosal and Z. Chen Bull. Math. Biol. 2010, vol. 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.

  17. Capillary Bridges between Soft Substrates (United States)

    Wexler, Jason S.; Heard, Tiara M.; Stone, Howard A.


    A wetting droplet trapped in the thin gap between two elastic bodies will deflect the bodies towards one another. The deformation increases the total capillary adhesion force by increasing the contact radius and narrowing the gap height. For flat droplets, with a large ratio of radius to gap height, the Laplace pressure causes surface deformations that are orders of magnitude larger than those induced by a sessile droplet of the same radius. We present experiments, scalings, and closed-form solutions that describe the deformation. Using variational techniques, we also show that the problem exhibits a bifurcation, where the gap spontaneously closes due to an incremental increase in drop volume.

  18. Effects of Capillary Forces and Adsorption on Reserves Distribution

    DEFF Research Database (Denmark)

    Shapiro, Alexander; Stenby, Erling Halfdan


    The purpose of this study is to evaluate the effects of capillary forces and adsorption on the distribution of a hydrocarbon mixture in an oil-gas-condensate reservoir. These effects consist in the precipitation of the liquid phase in thin pores and on the internal surface of the reservoir rock...

  19. Capillary electrophoresis application in metal speciation and complexation characterization (United States)

    Capillary electrophoresis is amenable to the separation of metal ionic species and the characterization of metal-ligand interactions. This book chapter reviews and discusses three representative case studies in applications of CE technology in speciation and reactions of metal with organic molecules...

  20. Frequency dispersion of small-amplitude capillary waves in viscous fluids

    CERN Document Server

    Denner, Fabian


    This work presents a detailed study of the dispersion of capillary waves with small amplitude in viscous fluids using an analytically derived solution to the initial value problem of a small-amplitude capillary wave as well as direct numerical simulation. A rational parametrization for the dispersion of capillary waves in the underdamped regime is proposed, including predictions for the wavenumber of critical damping based on a harmonic oscillator model. The scaling resulting from this parametrization leads to a self-similar solution of the frequency dispersion of capillary waves that covers the entire underdamped regime, which allows an accurate evaluation of the frequency at a given wavenumber, irrespective of the fluid properties. This similarity also reveals characteristic features of capillary waves, for instance that critical damping occurs when the characteristic timescales of dispersive and dissipative mechanisms are balanced. In addition, the presented results suggest that the widely adopted hydrodyn...