bluuebunny/crossref_metadata_2025_split huggingface dataset:
Extraction of near infra‐red spectral information by fast fourier transform and principal component analysis. Application to the discrimination of baking quality of wheat flours
Authors: Devaux Marie‐Françoise , Bertrand Dominique , Robert Paul , Morat Jean‐Luc 
Published: May 2005

AbstractDigitalized continuous near infra‐red reflectance (NIR) spectra are composed of a great number of data which must be reduced for microcomputer mathematical treatment. The sequence ‘fast Fourier transform preceding principal component analysis’ was tested to perform data size reduction without a large loss of information. The method was applied on a collection of wheat spectra composed of 351 data. Ten resulting data, which described 99.5% of the total variance, were kept. The relevance of the method was estimated by the ability of the resulting data (i) to regenerate the original signal, and (ii) to discriminate the baking quality of the wheat by stepwise multiple discriminant analysis. The average difference between initial and regenerated spectra was −2.4 × 10−3 log (1/R) units and the standard deviation was 1.16 × 10−3 log (1/R) units. The discrimination treatments gave 89.9% of well classified samples for the calibration test and 90.5% for the prediction test. The application of these mathematical treatments to other continuous signals is discussed.
Mechanism of the hydrolysis of adenosine 5′‐triphosphate: A regression analysis of kinetic data
Authors: Hibbert D. Brynn , Sandall John P. B. 
Published: May 2005

AbstractData of the hydrolysis of adenosine 5′‐triphosphate have been re‐evaluated using a computer program that numerically integrates the differential rate equations within a routine that optimizes rate coefficients given a suitable model and concentration versus time data.The model is tested by calculation of Hamilton R‐values, the Fisher F‐statistic, a sensitivity analysis, the standard errors on the rate coefficients and by constructing contour maps of the objective function versus two rate coefficients.An optimization using only phosphate concentration data cannot distinguish between a model in which adenosine 5′‐monophosphate is formed predominantly directly with a molecule of pyrophosphate, and one in which it is formed via adenosine 5′‐diphosphate. A more accurate set of rate coefficients is calculated from existing data and the relative importance of the two paths determined.
A bootstrap resampling scheme for using the canonical correlation technique in rank estimation
Authors: Tu Xin M. 
Published: May 2005

AbstractRank estimation by canonical correlation analysis in multivariate statistics has been proposed as an alternative approach for estimating the number of components in a multicomponent mixture. A methodological turning point of this new approach is that it focuses on the difference in structure rather than in magnitude in characterizing the difference between the signal and the noise. This structural difference is quantified through the analysis of canonical correlation, which is a well‐established data reduction technique in multivariate statistics. Unfortunately, there is a price to be paid for having this structural difference: at least two replicate data matrices are needed to carry out the analysis.In this paper we continue to explore the potential and to extend the scope of the canonical correlation technique. In particular, we propose a bootstrap resampling method which makes it possible to perform the canonical correlation analysis on a single data matrix. Since a robust estimator is introduced to make inference about the rank, the procedure may be applied to a wide range of data without any restriction on the noise distribution. Results from real as well as simulated mixture samples indicate that when used in conjunction with this resampling method, canonical correlation analysis of a single data matrix is equally efficient as of replicate data matrices.
Thin film growth and microstructure analysis of CeO2 prepared by MOCVD
Authors: Becht Michael , Morishita Tadataka 
Published: May 2005

AbstractCeO2 Thin films were prepared by metal‐organic chemical vapor deposition (MOCVD) using tetrakis(2,2,6,6‐tetramethyl‐3,5‐heptanedionato)cerium(iv), [Ce(thd)4], as the precursor. The films were grown in a horizontal cold‐wall reactor at low pressure and temperatures of 400–900°C in an atmosphere of argon/oxygen. SrTiO3, yttria stabilized zirconia (YSZ), and MgO were used as substrates. Films were prepared on single crystalline substrates with a (100) orientation as well as on polycrystalline YSZ. The film microstructure was investigated by X‐ray diffraction and the surface morphology was studied by scanning electron microscopy (SEM). The growth rate was determined using data obtained by profilometry and cross‐section SEM. The films are polycrystalline with a (100) preferential orientation with respect to the substrate orientation. Low oxygen partial pressures deteriorated the crystalline quality. The SEM images of the surface and the cross sections demonstrated a columnar microstructure. The growth rates in the range of 25–250 nm/h were strongly dependent on the precursor feeding rate but less affected by the deposition temperature and substrate material.
Amperometric glucose sensors based on glucose oxidase immobilized in nafion
Authors: Rishpon Judith , Gottesfeld Shimshon , Campbell Carmen , Davey John , Zawodzinski Thomas A. 
Published: May 2005

AbstractA glucose‐sensitive electrode composed of glucose oxidase (GOX) embedded in a layer of the polymer Nafion is described. Electrodes of various configurations on which the layer was cast were tested to determine their response to glucose additions to phosphate buffer and human whole serum samples. These electrodes have good response characteristics and several desirable features. Glucose sensors based on Nafion/GOX layers cast onto platinum electrodes respond to glucose additions with a rapid response time (2 to 4 seconds), have a long lifetime when stored in a phosphate buffer (55 days before termination of testing), have a reduced sensitivity to local oxygen tension, respond linearly to additions of glucose to the serum, and are not fouled by exposure to blood. The Nafion confers some permselectivity on the layer, thus providing a degree of discrimination against anioni interferents.
Dual wall‐tube electrode cell for use in clay‐modified electrode studies
Authors: Stein Jennifer A. , Fitch Alanah 
Published: May 2005

AbstractA dual tube‐electrode cell has been constructed for use in clay‐modified electrode (CME) studies. The optimization and characterization of the wall‐tube cell through both visual and electrochemical measurements is described. Its use in some CME studies is then described. The system is found to give excellent insight into the behavior of a CME.
Ion‐exchange properties of poly(L‐lysine) coatings on pyrolytic graphite electrodes
Authors: Bianco Pierre , Haladjian Jean , Giannhndrea Sophie 
Published: May 2005

AbstractPyrolytic graphite electrodes are coated with films of poly(L‐lysine) (PLL). The polyelectrolyte films bind multiply charged counterions. Cyclic voltammetry is used to investigate the incorporation of Fe(CN) anions as a function of time, concentration, pH, and ionic strength. The stability of the film is studied after transfer of the PLL coatings into an electrolyte solution. The PLL‐modified pyrolytic graphite (PG) electrode proves to be very effective in facilitating electron transfers of negatively charged proteins, such as ferredoxin and hydrogenase.
Copper‐sensitive modified poly(pyrrole) electrode
Authors: Arca Meral , Yildiz Attila 
Published: May 2005

AbstractA copper ion sensitive poly(pyrrole) electrode, containing diethyldithio‐carbamate as a ligand is described. The ligand was incorporated into the electrochemically‐prepared polymer coating via anion exchange. Cyclic voltammetry and infrared spectroscopy were used to characterize the modified electrode surface. The uptake of copper ions was achieved by electroreduction at −0.65 V (vs. SCE), and the cyclic‐voltametric anodic peak current of the complex ion at +0.55 V (vs. Ag/AgCl) was used for analysis. A detection limit for copper ions was estimated to be 1 ppm.
Electrocatalytic reduction of hydrogen peroxide on a palladium‐modified carbon paste electrode
Authors: Cai Xiaohua , Kalcher Kurt , Kölbl Gottfried , Neuhold Christian , Diewald Wolfgang , Ogorevc Bozidar 
Published: May 2005

AbstractA palladium‐dispersed carbon paste electrode was used for the electrocatalytic reduction of hydrogen peroxide. After cycling the potential between 0.4 and −0.8V (vs. SCE) in pure dilute alkaline solution (10−3M NaOH), the resulting electrode surface exhibited stable and sensitive electrocatalytic response for hydrogen peroxide. The involved catalytic mechanism was thoroughly investigated. The electrocatalytic effect was attributed to electrogenerated elemental palladium at the electrode surface. The catalytic reduction of hydrogen peroxide proceeds via the hydroxyl radical, OH·. Dissolved oxygen can also be catalytically reduced in a similar way to hydrogen peroxide. The height of the cathodic catalytic current peak, as obtained by linear sweep voltammetry (LSV) was directly proportional to the hydrogen peroxide concentration over a very wide concentration range (0.1–600mgL−1). The detection limit (3σ) was calculated as 50 μgL−1 H2O2.
Detection of new features associated with the oxidation of microcrystalline tetrathiafulvalene attached to gold electrodes by the simultaneous application of electrochemical and quartz crystal microbalance techniques
Authors: Shaw Shannon J. , Marken Frank , Bond Alan M. 
Published: May 2005

AbstractSimultaneous voltammetric or double potential step and quartz crystal microbalance experiments combined with the results obtained from optical and surface analysis measurements have allowed new mechanistic aspects of the electrochemical oxidation of microcrystalline particles of tetrathiafulvalene (TTF) attached to a gold substrate, which is placed in aqueous electrolyte media, to be unravelled. The use of the microcrystalline form of the solid rather than thin films makes it possible to obtain short time domain data which enables features for the reduction and the oxidation process consistent with a nucleation process at the solid electrode‐aqueous electrolyte interface to be detected. Electrochemical quartz crystal microbalance (EQCM) and electron microprobe analysis experiments confirm that the overall process in the oxidation of microcrystals of TTF in aqueous KBr, KI, KClO4, NaBr and CsBr electrolyte media involves the uptake of the appropriate nonsolvated anion (X‐) in order to maintain charge neutrality. Reduction of the oxidized TTF leads to the expulsion of the anion. The rates of uptake and expulsion are both very rapid for the bromide ion, but involve slower reaction steps for iodide and perchlorate anions. The oxidation of TTF particles attached to a gold electrode can be described by the equation

The number of electrons transferred to the solid, n, may theoretically vary over a wide range, but in the case of X− =Br− is found to be fixed with only one product formed (n =0.7). The peak potential and shape of voltammograms have been studied as a function of scan rate, electrolyte concentration and the nature of the anion and cation. A Nernstian change in peak potential is observed when the electrolyte anion concentration is varied. The wave shape, but not the charge, also varies with electrolyte anion and concentration. In contrast, no dependence on the electrolyte cation is found. All the data imply that incorporation of the anion into the solid provides the charge neutralization mechanism. This study confirms that use of microcrystalline forms of a solid enables a wide range of time domains (and techniques) to be applied to electrochemical studies of solids.
Cyclic voltammetry of a unique quinone–quinol equilibrium
Authors: Maali Nagwa Abo El , Berg Hermann 
Published: May 2005

AbstractThe thermochromic quinone‐quinol equilibrium of more than 20 derivatives was studied by classical DC‐polarography. This tautomery causes one reversible two‐electron wave and one irreversible (about 1 V) more negative wave. This double‐wave current‐voltage curve occurs only in the case of one asymmetric oxyethylamino substitution in the 2‐position for benzoquinones and for naphthoquinones. Our present investigations characterize further this unique slow equilibrium by the influence of the scan rate ν on cyclic voltammograms. The peak potentials are shifted to more negative values with increasing ν. Both the heights of the second wave and of the positive anodic step increase linearly with ν, whereas the height of the positive kinetic reduction wave behaves similarly only when ν < 25mVs−1. However, at ν > 50mVs−1the decyclization rate of quinol to quinone has no further influence on the first peak height andk2was determined directly and independently of former DC‐polarographic and spectrometric results.
The effect of zinc(II) and some chromium complexes on the constant current chronopotentiometry of insulin
Authors: Honeychurch Michael J. , Ridd Michael J. 
Published: May 2005

AbstractThe constant current chronopotentiometry (CCCP) of zinc‐free insulin was examined and the effect of additions of zinc(II) or either of two chromium complexes to the zinc‐free zinc was studied. The zinc free insulin gave a constant current chronopotentiometric (CCCP) response which indicated that the freeze drying process, which was part of its preparation, may have denatured the insulin. The addition of zinc(II) appeared to reverse this since the response following zinc additions was similar to that of native insulin. Of the two chromium complexes investigated for their influence on insulin electrochemistry tripicolinato chromium(III) had no effect on the CCCP response, trans‐Diaquoethylenebis‐(salicylideneiminato) chromium(III) had an indirect effect by appearing to restore the native conformation of the insulin following the apparent denaturation caused by the removal of zinc.
Staircase voltammetry with finite diffusion space
Authors: Lovrić Milivoj , Komorsky‐Lovrić Šbojka , Scholz Fritz 
Published: May 2005

AbstractA theory of the staircase voltammetry in a thin‐layer cell is developed. The influence of the cell thickness and the redox reaction rate constant on the current and the peak potentials is analyzed. For moderately thick cells, the kinetic maximum is predicted. The relationship between peak currents and the square root of the scan rate is not linear and the response may entirely vanish if the redox reaction is fast, the cell is very thin and the scan rate is slow.
Modification of pH gradients in isolelectric focusing by the pH of the anolyte
Authors: An der Lan Birgit , Chrambach Andreas 
Published: May 2005

AbstractIn isoelectric focusing on polyacrylamide gel, pH gradients exhibited a systematic shift along the pH‐axis in proportion to the pH of the anolyte. Thus, more acidic anolytes produced more acidic pH gradients, and more basic ones gave rise to more basic pH gradients. In all cases the pH's of the anolyte and catholyte were kept outside the pI‐range of the carrier ampholytes used. Increasing the pH of the anolyte stabilized pH gradients, while the pH of the catholyte, within the range tested, had no systematic effect on pH gradient stabilization.From a practical viewpoint, modification of pH gradients by the anolyte provides increased flexibility in pH gradient design for electrofocusing. From a theoretical viewpoint, the selective anolyte effect on pH gradients in isoelectric focusing on polyacrylamide gels supports the hypothesis previously advanced by Murelet al., which relates pH gradient decay in electrofocusing to progressive protonation from the anodic pH gradient terminus.
pH Gradient flattening in isoelectric focusing in long polyacrylamide gels
Authors: Rapaport Ray N. , Jackiw Andrew , Brown Ray K. 
Published: May 2005

AbstractIsoelectric focusing in 60 cm long gels improves resolution in multiple‐component systems by providing very shallow, linear pH gradients. Broad range ampholytes available commercially or synthesized in our laboratory develop pH gradients of 0.1 pH/cm at voltages of 1500 to 4500 V, with running times of 25–30 h. Shallower gradients result with narrow range ampholytes or separator isoelectric focusing. Hemoglobin, human serum albumin, and an α‐N‐acetylgalactosaminidase have been used for defining this system.
Distorted zones in isoelectric‐focusing systems
Authors: Jonsson Mats 
Published: May 2005

AbstractA maximum utilization of the high resolving power of isoelectric focusing requires that the focused zones are both planar and perpendicular to the direction of focusing. This paper reports on extensive investigations carried out with a rectangular quartz column with provisions for direct photography of zonal shapes. The experiments have been performed in density gradients, but the conclusions may be generalized to other stabilizing media. It is demonstrated that distorted zones are formed if a second pH gradient, perpendicular to the direction of focusing, originates at one end of the column. The generation of such a pH gradient may have different causes: erroneous loading of the column, too high an initial power input, presence of salts of weak electrolytes in the sample, or unsuitable positioning of the electrodes. The effects of the second pH gradient on the shapes of the focused carrier‐ampholyte and protein zones are interpreted on the basis of the mechanism creating the natural axial pH gradient. The stability of the disturbed system is discussed in terms of the diffusional, electrical, and convective mass flows of its components.
An investigation into the mechanism of electrophoretic desorption of immunoglobulin G from protein A‐Sepharose
Authors: Haff Lawrence A. 
Published: May 2005

AbstractThe effect of voltage on the rate of desorption of radiolabeled rabbit immunoglobulin G (IgG) from protein A‐Sepharose was studied. In the absence of voltage, the rate of desorption was measured using a vast excess of unlabeled IgG to prevent re‐adsorption. Electrophoretic desorption was measured using a column equipped with electrodes and with eluent flow occurring in the direction of electrophoresis. The rate of desorption was very sensitive to voltage, and, furthermore, desorption could occur at a rate 25 times faster than in the absence of a voltage. The results are interpreted to indicate that the presence of voltage not only altered the equilibrium of the system but altered the equilibrium or rate constants of the system.
Cellulose acetate electrophoresis of glycosaminoglycans: Determination of concentration and specific activity by solid‐phase spectrophotomertry and fluorography
Authors: Stack Michael T. , Golichowski Alan M. 
Published: May 2005

AbstractA simple method for the quantitative determination of glycosaminoglycan concentration and radioactive precursor incorporation into glycosaminoglycans is describe. Tissue glycosaminoglycans are separated by electrophoresis on cellulose acetate sheets. Sheets are then impregnated with diphenyloxazole in toluene and tritium activity quantitated by fluorography. Absolute absorbance measurement of X‐ray film fluorograms exposed for 80 h demonstrate a sensitivity of 50 dpm per samle (< 5 dpm/mm2) and reproducibility of 7% Diphenyloxazole is removed with toluene and the sheets are stained with Alcian Blue. Absolute absorbance determination allow quantity measurement of mass with a sensitivity of 0.05 nmol of disaccharide subunit and a reproducibility of 6%. Beer's law is followed to 3nmol. Example of the utilization of this technique in studying radionuclide incorporation into glycosaminoglycans in these tissues‐ articuular cartilage, uterine cervix and skin‐are presented.
Simplified silver protein detection and image enhancement methods in polyacrylamide gels
Authors: Merril Carl R. , Goldman David , Van Keuren Margaret L. 
Published: May 2005

AbstractThe use of silver for detection of protein in polyacrylamide gels is becoming widespread. An effort has been made to develop a silver stain which minimizes the time to perform the stain, the amount of silver used, and the complexity of the procedures, and which maximizes the sensitivity. This stain is almost 200‐fold more sensitive than the Coomassie Brilliant Blue R‐250 stain. This silver stain procedure has been shown, with eight purified proteins, to generally be linear over a 40‐fold range in concentration, between 0.005 ng/mm2 to 2.0 ng/mm2. For greater sensitivity, a recycling procedure has been developed. This procedure is capable of amplifying trace proteins which could not be visualized with previous silver stain techniques. Analysis of the kinetics of image development revealed that the silver ion was the limiting factor in image formation. By recycling the gel through silver nitrate solutions, silver ions are replenished in the gel, permitting amplification of further details when the gel is treated with a developing solution. A number of problems inherent in silver stain detection of proteins in polyacrylamide gels are discussed with suggested remedies.
A procedure for stabilization of cytopherometers for immunological applications
Authors: Koenig Ulf D. , Bongartz Lothar , Kozan A. Burak 
Published: May 2005

AbstractA device commonly used for cell electrophoresis is the cytopherometer. Its application in an immunological tumor test, however, pointed out many shortcomings and instabilities. In order to use cytopherometers in cellular immunology, a procedure was worked out to stabilize this instrument. By enlarging the electrode chambers, using a simple and efficient buffer in all compartments, coating the electrophoresis chamber, and by following a set of electrophoretic parameters (current, temperature, etc.), an intraassay variance of 1.8 % and an interassay variance of approximately 1 % were reached.
Improved isoelectric focusing of normal and variant forms of erythrocyte galactose‐1‐phosphate uridyl transferase
Authors: Vaccaro Anna M. , Muscillo Michele , Mandara Ida , Salvioli Rosa 
Published: May 2005

AbstractAn improved isoelectric focusing (IEF) technique has been developed and used to detect the erythrocyte galactose‐1‐phosphate uridyl transferase isoenzymes. The normal enzyme was resolved by IEF in four bands with isoelectric points (pI) between 5.80 and 6.08. Numerous samples, classified according to electrophoresis as Duarte or Los Angeles homozygotes, showed the same IEF pattern composed of four bands with pI's between 5.60 and 5.90. The Duarte‐normal and Los Angelesnormal heterozygotes gave an IEF pattern of 4‐5 bands (pI 5.60‐6.08), with relative intensities that varied according to their activity.