bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of hydrogen fluoride on the anodic behavior of glassy carbon in aqueous and mixed aqueous solutions
Authors: Noel Michael , Santhanam Raman , Ravikumar Musuwathi K. , Flora Mangalam Francisca 
Published: May 2005

AbstractThe electrochemical behavior of the glassy carbon electrode (GCE) in aqueous 1.0–20.0 M HF solutions and in mixed solvents containing 15.0 M HF (25 vol.%) was investigated using cyclic voltammetry, chronoamperometry and surface microscopic analysis. The GCE shows three surface redox peaks in aqueous HF solutions which become distinct at higher HF concentrations. Fresh surface oxidation and slight surface roughening occurs above 1.6 V. The background current increases significantly due to strong anodic polarisation in HF solutions. However, the electrode activity as measured by the response of the ferricyanide/ferrocyanide redox system remains unaltered. In mixed solvent systems, the surface redox currents and fresh surface oxidation decrease significantly. The oxygen evolution occurs at less positive potentials. Thus the electrochemical activity in such systems is much better.
Surface charge density measurements with a controlled growth mercury electrode
Authors: O'Dea John J. , Ciszkowska Malgorzata , Osteryoung Robert A. 
Published: May 2005

AbstractThe surface charge density of the mercury‐electrolyte interface is estimated using chronocoulometry at a controlled growth mercury electrode. After initial formation and equilibration the mercury drop is expanded by further addition of mercury. Direct measurement of the charge required as new area is formed is used to estimate the surface charge density. The mercury drop is modeled as a step‐wise expanding sphere.The capillary noise continuously produced by stationary drops under potential control was investigated and characterized. Spectral analysis of the noise reveals that the electrode is particularly sensitive to vibrations near the resonant frequency of the suspended drop. Ambient vibrations in the laboratory environment produce alternating currents at the electrode which vanish at the point of zero charge and so mark its position.
Multichannel electrochemical analyses of enzyme reactions
Authors: Kasai Nahoko , Matsue Tomokazu , Uchida Isamu 
Published: May 2005

AbstractHorseradish peroxidase (HRP) and xanthine oxidase (XOD) reactions were investigated using a multichannel electrochemical detector with 16 independent band electrodes held at different potentials. Although the enzyme reaction media gave complicated electrochemical responses in flow injection analysis, responses for a redox species can be extracted easily from the multichannel responses. The course analysis over time of the extracted responses enabled the Michaelis constants and molecular activities of HRP for various electron donors to be established. The electrochemical responses of O on the μM order in aqueous solution were also washed out from the responses in the XOD reaction media.
Electroreductive cleavage of propargylic acetates through polarity inversion of in situ generated allenyl palladium(II) complexes and, in part, unusual chemical reduction induced by phosphine ligand
Authors: Tanaka Hideo , Takeuchi Hiroaki , Ren Qinghua , Torii Sigeru 
Published: May 2005

AbstractThe electroreduction of propargyl acetates in the presence of a catalytic amount of PdCl2(PPh3)2/PPh3 in DMF containing Et4NOTs at ambient temperature under a constant current density (10 mA/cm2) afforded the corresponding allenes in 43–84% yields. The time‐course of the reaction was monitored by HPLC, indicating that the allenes were formed immediately after the current was applied and that most of the starting materials were consumed when less than the theoretical amount of electricity (2 F/mol), typically 1.2–1.7 F/mol, was reached. Interestingly a considerable amount of phosphine oxide was formed in the electroreduction media. Neither the reductive cleavage of the propargylic acetates nor the formation of phosphine oxide occurred without electricity being applied. The unusual results suggest that chemical reduction with the phosphine ligand would take place, in part, during the course of the electroreduction. A plausible reaction mechanism is proposed involving electroreductive polarity inversion of in situ generated allenyl PdII‐complex as well as chemical reduction with the triphenylphosphine ligand leading to allenyl anion species.
Application of poly(cyclophosphazene) for potentiometric detection of tributyl phosphate vapor
Authors: Li Jing , Janata Jiří , Josowicz Miru 
Published: May 2005

AbstractPotentiometric sensing layer for detection of tributyl phosphate (TBP) in the concentration range from 1.1 ppb up to 8.8 ppm is described. The high sensitivity to TBP is based on a specific charge‐transfer interaction that occurs between iodine species and the oxygen atom of the phosphoryl group of TBP. The iodine is incorporated electrochemically or chemically into a chemically inert poly(cyclophosphazene‐benzoquinone), PPBQ. matrix. The bulk involvement of the new material in the interaction with the TBP vapor leads to modulation of its Fermi level. The number of' moles of charge shared by the TBP with thc sensitive layer is between 0.8 to 0.9 in the range of concentrations between 0.27 and 8.8 ppm. The interaction is highly reversible and reproducible.
Ultrasonic effects on electroorganic processes. Part 4: Theoretical and experimental studies on product‐selectivity in electroreduction of benzaldehyde and benzoic acid
Authors: Atobe Mahito , Matsuda Kazuya , Nonaka Tsutomu 
Published: May 2005

AbstractProduct‐selectivity in the electroreduction of p‐methylbenzaldehyde and benzoic acid under ultrasonic irradiation are examined theoretically and experimentally on the basis of mass transport phenomena in lhe electrode interface. As a result, it was suggested that the selectivity is controlled by mass transfer coefficients which are greatly affected by cavitation and/or agitation effects of ultrasounds.
Determination of tin(II) in pharmaceuticals by amperometric oxidation after complexation with tropolone
Authors: Boutakhrit K. , Quarin G. , Özkan S. A. , Kauffmann J.‐M. 
Published: May 2005

AbstractInorganic tin(II) was determined, rapidly and selectively in the presence of tin(IV), by electrooxidation after complexation with tropolone (2‐hydroxy‐2,4,6‐cycloheptatrienone). By cyclic voltammetry, the tin(II)‐tropolone complex showed a well‐defined irreversible oxidation peak which occurred at −0.014 V (vs. Ag/AgCI) at the glassy carbon electrode in 0.05 molL−1 acetate buffer pH 5.5. The determination of SnII has been realized using FIA and by poising the electrode at +0.1 V. A linear relationship was obtained between peak current and tin(II) in the concentration range 0.25–20 μmolL−1. The detection limit was 0.1 μmolL−1 and the RSD calculated by injection of a 5 μmolL−1 tin(II) solution was 1.5% (n = 10).The optimization of several experimental parameters bas been realized and the influence of many cations and possible interfering species encountered in radiopharmaceuticals and in dental gels has been investigated. The method was applied to the determination of tin(II) in dental gels.
Amperometric alcohol sensors based on protein multilayers composed of avidin and biotin‐labeled alcohol oxidase
Authors: Du Xiao‐yan , Anzai Jun‐ichi , Osa Tetsuo , Motohashi Ryoichi 
Published: May 2005

AbstractProtein multilayers composed of avidin and biotin‐labeled alcohol oxidase (AOx) were prepared on the surface of a platinum (Pt) electrode by repeated deposition of the proteins to develop amperometric alcohol sensors. The AOx multilayer‐modified sensors showed a rapid response to ethanol over the concentration range of 0.01–10mg/100mL. The output current of the sensor depended linearly upon the thickness of the AOx layers (or the number of the AOx layers), suggesting that a constant amount of AOx can be immobilized by each deposition. The selectivity of the sensor to aliphatic alcohols was in the order of methanol > ethanol > n‐propanol > n‐butanol, being in accord with the selectivity of AOx in a homogeneous system itself. The sensor retained its original response to ethanol for about one month without deterioration.
The transfer of chloride ion across an anion exchange membrane
Authors: Wang Hanming , Yu Zemu , Wang Erkang 
Published: May 2005

AbstractThe transfer of chloride ions into a low resistance anion exchange membrane (AEM) was investigated by cyclic voltammetry (CV) and electrochemical impedance spectra. In all cases, concentration polarization of C1− ions is exterior to the membrane. It controls the flux and produces the limiting currents: either steady state or transient (peak type) current. In CV experiments, when the size of the holes in the membrane was much smaller than the distance between membrane holes, the C1− anion transfer showed steady state voltammetric behavior. Each hole in the membrane can be regarded as a microelectrode and the membrane was equivalent to a microelectrode array in this condition. When the hole in the membrane was large or the distance between membrane holes was small, the CV curve of the C1− anion transfer across the membrane showed a peak shape, which was attributed to linear diffusion. In AC impedance measurement, the impedance spectrum of the membrane system was composed of two semicircles at low DC bias, corresponding to the bulk characteristics of the membrane and the kinetic process of ion transfer, respectively. The bulk membrane resistance increases with increasing DC bias and only one semicircle was observed at higher DC bias. The parameters related to kinetic and membrane properties were discussed.
Electrofocusing on flat pH gradients: Systematic pH gradient modification leading to improved protein separation
Authors: Nguyen Nga Y. , Chrambach Andreas 
Published: May 2005

AbstractA pH gradient providing maximal separation between pH 4.7 and 4.9 was generated by systematic variation of carrier constituent mixtures, and/or selection of anolyte/catholyte. In the optimized pH gradient, separation on gel electrofocusing between proteins with pI's between 4.7 and 4.9 was shown to be superior to that achieved on relatively steep pH gradients. This was the case in the separation of either human growth hormone isohormones D and E, or of bovine serum albumin and ovalbumin.
Ultrathin‐layer isoelectric focusing in 50–100 μm polyacrylamide gels on silanized glass plates or polyester films
Authors: Radola Bertold J. 
Published: May 2005

AbstractUltrathin‐layer isoelectric focusing in 50–100 μm polyacrylamide gels covalently bound to glass plates or polyester films, pretreated with methacryloxypropyl‐trimethoxy‐silane, is described. The gels adhere firmly to the silanized supports during all steps of operation and visualization. Ultrathin gels are prepared by the new and simple “flap technique”. Artificial mixtures of marker proteins and crude fungal enzymes were focused on 5–25 cm separation distances. In 11 cm gels containing pH 4–9 “Servalyt T” carrier ampholytes, 2–3 zones per mm can be resolved, with a zone width of 70–150 μm and differences in pI values of 0.023–0.033 pH. The gel volume per focused sample is 15–120 μl and up to 100 samples can be analyzed on 12.5 × 26 cm gels. Polyacrylamide gels of intermediate and high porosity, e. g. 5 % T, 3 % C and 3 % T, 20 % C, are compared. Small marker proteins attain equilibrium in both gels after focusing for 1300–2000 V x h at a final field strength of 100 V/cm, whereas thyroglobulin (690 000) and ferritin (465 000), applied at the anode and cathode, coalesce only in high‐porosity gels. pH Gradients were determined, with the aid of a glass electrode, directly on the gel surface for wide range carrier ampholytes “Servalyt T”, “Ampholine”, and “Pharmalyte” after focusing for 2000–5000 V × h. Identical focusing patterns are found for some marker proteins and crude fungal enzymes in different carrier ampholytes. The effect of purification of commercial carrier ampholytes by ultrafiltration and charcoal treatment, and of “forced aging” at 80°C, on isoelectric focusing of marker proteins was studied. The molecular size distribution of different carrier ampholytes was assessed by thin‐layer gel chromatography on Bio‐Gel P‐10. Protein staining with Serva Blue G, Serva Blue R and Serva Violet 49 is described. The sensitivity of protein detection is 50–100 ng/mm2. Fixation, staining and destaining can be completed within 10–15 min in 50 μm gels. Ultrathin‐layer isoelectric focusing on silanized glass plates or polyester films recommends itself as an excellent analytical technique for research and routine applications. The method combines high resolution, speed, versatility and reagent economy with simplicity of operation.
Flattening, shifting and comparing pH gradients in slab gel electrofocusing by local increases of gel volume
Authors: Altland Klaus , Kaempfer Michael 
Published: May 2005

AbstractA simple and versatile technique of horizontal slab gel electrofocusing is described which is based on a discontinuity of the gel volume along the pH axis achieved by overlaying ampholyte containing gel strips, of a defined volume and shape, at various locations on a base gel during the prerun of isoelectric focusing. In the electric field the overlaid gel strip delivers ampholytes of a distinct pI interval into the strip‐free part of the base gel and removes from the latter some ampholytes present in the system. Flattening of the pH gradient in the strip‐free part of the gel is the consequence. The technique is especially useful for thin gels and can be performed with any commercially available horizontal slab apparatus.
A comparison of crossed immunoelectrophoresis and crossed immunoelectrofocusing for the investigation of human salivary proteins
Authors: Eckersall Peter D. , Beeley Josie A. 
Published: May 2005

AbstractUsing two dimensional immunological electrophoretic techniques, it is possible to study the antigens in microlitre quantities of saliva without prior concentration. Under the conditions used, crossed immunoelectrophoresis was superior to crossed immunoelectrofocusing in that the former revealed a greater heterogeneity of salivary components. Both methods showed that there is considerable variation between individuals in the proportions of the different antigens present. Levels of some of the salivary antigens in a single individual were consistent between samples collected at different times of day. α‐A mylase was the major antigen of parotid saliva while the submandibular/sublingual secretion contained a wider spectrum including a major acidic antigen.
Principles and instrumentation of analytical cell electrophoresis
Authors: Catsimpoolas Nicholas 
Published: May 2005

AbstractMeasurement of the electrophoretic mobility of cells can be performed with various types of apparatus. Basically, these instruments can be classified into two broad categories i.e. those where physical separation does not take place and those which actually separate cell populations according to their surface charge. The former category includes the microscopic/image analysis method and the laser light scattering Doppler velocimetry apparatus. These two types of instruments can be used only for analytical purposes. Physical separation combined with analytical capabilities requires some form of anti‐convection stabilization of the separated species. This can be accomplished by capillary action, mechanical or electromagnetic rotation, and flowing or stationary density gradients. Several instruments exist which utilize each of the above principles. Monitoring of the separation is usually performed by optical scanning.
Purification of pepsinogen I from human urine by means of DEAE‐chromatography and isotachophoresis
Authors: Axelsson Christen Kirk , Axelsen Nils Holger , Svendsen Per Just 
Published: May 2005

AbstractThe present paper gives a description of a procedure for isolation of pepsinogen I from human urine. The initial steps are concentration by batch adsorption to DEAE‐Sephadex, desorption by addition of NaCl, and DEAE‐chromatography. The final step is preparative isotachophoresis with Ampholine carrier ampholytes as spacers. Exact visualization of the fractionations is obtained by fused rocket immunoelectrophoresis. The procedure provides pepsinogen I of high purity as shown by crossed immunoelectrophoresis, agar gel electrophoresis and N‐terminal aminoacid analysis. The yield of the procedure is 0.05–0.1 mg pepsinogen I per liter urine.
Assay of UDP‐glucuronyltransferease with mixtures of acceptors using analytical capillary isotachophoresis
Authors: Holloway Christopher J. , Husmann‐Holloway Sabine , Brunner Gorig 
Published: May 2005

AbstractAnalytical capillary isotachophoresis has been applied as an analytical tool for the assay of the microsomal enzyme UDP‐glucuronyltransferase, which is an important system for the detoxification of drugs and many endogenous and exogenous toxins. The substrate donor molecule UDP‐glucuronic acid, various products of hydrolytic cleavage, and the products of glucuronidation β‐glucuronides, can be assayed in a single run. Furthermore, the glucuronidation of mixtures of acceptors can be monitored simultaneously, since the various β‐glucuronides are separated from one another. This method offers a more comprehensive assay of glucuronidation reactions than has been possible using previously published procedures.
Gel electrophoresis salivary mucins
Authors: Kashket Shelby , Ciociolo James M. 
Published: May 2005

AbstractBovine Submaxillary mucin (BSM) and human submandibular mucin (HSM) were electrophoresed in a system in which the mucins were incorporated into an agarose sample gel and separation was carried out in a 5 % polyacrylamide gel. BSM was resolved into two protein‐ and carbohydrate‐containing bands, and a number of non‐mucin proteins. When the electrophoresis was carried out at 80°C, the mobilities and resolution of the bands were increased. The entry of HSM into the running gel was also increased at the elevated temperature and the samples were separated into at least four protein‐ and carbohydrate‐stainable bands. Protein bound sialic acid remained unchanged unter these conditions and aggregating activity for cells of a strain of oral streptococcus could be recovered from the gels after the electrophoresis. The facilitation of the electrophoresis of human mucus glycoprotein's at high temperature may reflect the dissociation of macromolecular aggregates of the mucins under these conditions. A number of purified, non‐mucin proteins also moved as discrete bands at 80degreeC. It is suggested that electrophoresis at elevated temperatures should be considered generally for the analysis of multimolecular systems that are of biological importance.
Ultrasensitive silver‐based color staining of polypeptides in polyacrylamide gels
Authors: Sammons David W. , Adams Lonnie D. , Nishizawa Edwards E. 
Published: May 2005

AbstractA color development system for staining polypeptides in one‐ and two‐dimensional polyacrylamide gel electrophoresis is described. The basis of the Process involves the complexing of silver with polypeptides reactive centers. The reaction is initiated by placing a polypeptide‐containing gel, previously equilibrated with an appropriate concentration of silver nitrate, into a reducing solution that contains sodium hydroxide, sodium borohydride, and formaldehyde. After an appropriate time in the reducing solution, the gel is equilibrated through two changes of an enhancing solution that contains sodium carbonate. The sodium carbonate is necessary for optimal color appear in the polypeptide ‐silver complexes after several hours in the enhancing solution and are best appreciated while viewing over a fluorescent light box that radiates light at 5000°K. The color of each polypeptide‐silver complex is clearly visible above the light background of the stained polyacrylamide gel. Colors of stained polypeptide are blue, green, yellow, and red. Subtle shades of colors also appear and thereby allow easy discrimination of overlapping spots of polypeptides in a two‐dimensional gel. To illustrate the method's relative sensitively, a two‐dimensional pattern of human fibroblast polypeptides is compared with patterns of a duplicate gel that is stained with Coomassie Blue and developed by autoradiography. The sensitivity of the silver stain process is superior to Coomassie Blue and is comparable to autoradiography after in corporation of conventional levels of 35S‐ methionine. The utility of the procedure for identifying and characterizing human proteins is illustrated by staining human proteins is illustrated by staining human plasma and platelet polypeptides after two‐dimensional gel electrophoresis. The gel electrophoresis color development system consists of steps that are simple, reproducible, and sensitive, and most importantly, which yield colored polypeptide‐silver complexes that are reproducible from gel to gel and tissue to tissue.
The nature of observed schlieren patterns in isoelectric focusing gels and their use for position of banded proteins
Authors: Edwards Jesse J. , Anderson Norman G. 
Published: May 2005

AbstractA simple and versatile optical technique for viewing discontinuities in the thickness of horizontal isoelectric focusing gels is described. The discontinuities in the gel are reproducible and relate directly to the ampholyte distribution. Characterization of the capture of the discontinuities in the gel is presented as well as a demonstration of how they may used for localization of focused proteins.
Miniature ultrathin‐layer isoelectric focusing in 20–50 μm polyacrylamide gels
Authors: Kinzkofer Angelica , Radola Bertold J. 
Published: May 2005

AbstractUltrathin‐layer isoelectric focusing in polyacrylamide gels on silanized supports provided the means for developing a miniature system combining short focusing time with high resolution and operational simplicity. The essence of miniature ultrathin‐layer isoelectric focusing is the combined use of short separation distances (1–3 cm) and high field strengths (400–700 V/ cm), which can be applied in standard equipment simply by reducing the thickness of the gel to 20–50 um for improved heat dissipation. By the criterion of coalescence of proteins migrating from different positions, a steady state is reached in pH 4–9 servalyt T carrier ampholytes on 1 cm gels after 2 min (15 Vh) and on 3 cm gels after 10 min total focusing time (110–130 Vh). On 3 cm gels the resolution is 0.03–0.035 pI in wide‐range carrier ampholytes, and 0.01–0.02 pI in narrow‐range (0.3 pH units) carrier ampholytes isolated by preparative isoelectric focusing of pH 4–9 Servalyt T in Bio‐Gel P‐60 layers. Miniature ultrathin‐layer isoelectric focusing can easily be adapted to the analysis of multiple samples. When the volume is limited to 0.2–0.4 μl, up to four samples per cm can be applied directly on the gel surface. At this loading, the gel volume per focused sample amounts to only 0.5–5 μl. The gel volume per sample is reduced by a factor of 10–200, relative to the 10–12 cm separation distance in 50–100 μm gel layers. This results in a considerable saving of carrier ampholytes and reagents for gel preparation. For serial dilutions of pH marker proteins, the sensitivity of protein detection after staining with Serva Blue G or Serva Violet 49 is 10–15 ng protein in the miniature system. Miniature ultrathin‐layer isoelectric focusing should prove to be an attractive method for routine applications in clinical, industrial and research laboratories in those cases when only small amounts of material are available or when rapid results are required. The method is particularly suitable for studies of genetic polymorphisms of proteins and enzymes.