bluuebunny/crossref_metadata_2025_split huggingface dataset:
Incorporating auxiliary predictor variation in principal component regression models
Authors: Thomas Edward V. 
Published: May 2005

AbstractIn analytical chemistry a single fitted calibration model is used repeatedly to predict the level of the analyte of interest for the specimens comprising the prediction set. Unlike the calibration (or training) set, which is often limited in size, the prediction set can be very large.In the case of multivariate calibration a number of methods such as PLS and PCR are commonly used to construct the calibration model. The set of instrumental measurements and the reference analyte level are available for each specimen in the calibration set. For specimens in the prediction set, only the instrumental measurements are available, since the problem is to predict the analyte level for these specimens. It is not widely recognized that predictions of the analyte levels for individual specimens can be improved by utilizing seemingly unrelated information from the instrumental measurements associated with the other members of the prediction set. In the case of PCR there exists a very straightforward procedure for doing this. A description of the various sources of prediction errors is provided to explain the ability of PCR to utilize this additional information. The use of PCR in this context is illustrated with both a synthetic and a real example.
On the structure of PLS in orthogonal designs
Authors: Langsrud Øyvind , Næs Tormod 
Published: May 2005

AbstractThis paper presents an interpretation of PLS applied to orthogonal explanatory variables. In particular, it is shown that in fractional factorial multiresponse experiments PLS2 gives identical results to ordinary least squares applied to principal components of the response variables. The general relationship is that the reduced‐rank regression algorithm which first projectsYonto theX‐space and then truncates this matrix by principal component analysis before performing ordinary least squares estimation gives the same predictor as PLS2 and SIMPLS if all the non‐zero eigenvalues ofXTXare identical.
Iteratively reweighted partial least squares: A performance analysis by monte carlo simulation
Authors: Cummins David J. , Andrews C. Webster 
Published: May 2005

AbstractA robust implementation of partial least squares (PLS) is developed in which the method of iteratively reweighted least squares is adapted for use with PLS. The result is a PLS algorithm which is robust to outliers and is easy to implement. Examples and case studies are presented, followed by two Monte Carlo studies designed to explore the behavior of the method.The paper begins with the motivation and intended applications for the procedure. A discussion is given of the method of interatively reweighted least squares (IRLS) for outlier detection. The procedure, given the name IRPLS, is then presented. Three case studies illustrate how the procedure works on various types of data and how it should be used. The first Monte Carlo study is designed to determine whether the IRPLS procedure correctly identifies multiple outliers in a wide variety of configurations. The second Monte Carlo study is designed to estimate the breakdown bound of the procedure.
Metal Chalcogenide Materials: Chalcogenolato complexes as “single‐source” precursors
Authors: Bochmann Manfred 
Published: May 2005

Modern inorganic materials are required to fulfill a range of demandsfor quality and performance in an increasing number of applications. Single‐source precursor molecules can satisfy many of these requirements. In this review article ligand design (leading, for example, to the dimer shown in the Figure) to address problems associated with gas phase pre‐reactions, thermal stability, ease of handling, toxicity, and purity for II‐VI deposition are discussed.magnified image
Low‐temperature chemical vapor deposition of indium sulfide thin films using a novel single‐source indium thiocarboxylate compound as precursor
Authors: Shang Guihua , Kunze Klaus , Hampden‐Smith Mark J. , Duesler Eileen N. 
Published: May 2005

The optoelectronic properties of gallium and indium chalcogenides have attracted considerable attention in recent years. This paper describes the synthesis and characterization of the first monomeric indium thiocarboxylate CVD precursor, with the molecular structure shown in the Figure. This compound has been successfully used to grow high purity, uniform, crystalline β‐In2S3 by aerosol‐assisted CVD at the lowest temperature (210°C) yet reported.magnified image
Low temperature deposition of AIN films by an alternate supply of trimethyl aluminum and ammonia
Authors: Riihelä Diana , Ritala Mikko , Matero Raija , Leskelä Markku , Jokinen Janne , Haussalo Pekka 
Published: May 2005

AbstractAIN thin films were grown by an alternate supply of trimethyl aluminum (TMA) and ammonia, i.e., according to the processing scheme of the atomic layer epitaxy (ALE) technique. In contrast with the ideal ALE process, no saturation of the growth rate was observed with increasing TMA pulse time. In addition, with fixed pulse times the growth rate was strongly temperature dependent. These observations were interpreted in terms of a self‐decomposition of TMA. Despite the absence of self‐limitation, the films were uniform and showed good structural quality. The deposition temperatures were remarkably low, 325–425°C, compared with CVD processes employing the same precursors. Time‐of‐flight elastic recoil detection analysis (TOF‐ERDA) and nuclear resonance broadening (NRB) measurements indicated that the films contained hydrogen, carbon, and oxygen impurities.
First liquid precursors for the CVD of palladium films
Authors: Zhang Yiping , Puddephatt Richard J. 
Published: May 2005

Communication: There is much interest in the CVD of Pd films, which have a range of major applications. For Pd CVD, liquid precursors have many practical advantages and this paper reports the results of a systematic search for such precursors. Two have been found with the structure shown in the Figure, R1, R2, and R3 being either H or Me and R′ = tBu AND r″ = C3F7 in both cases.magnified image
A Study of Stress in Microwave Plasma Chemical Vapor Deposited Diamond Films Using X‐Ray Diffraction
Authors: Haque M. Shahidul , Naseem Hameed A. , Malshe Ajay P. , Brown William D. 
Published: May 2005

AbstractResidual stress in polycrystalline diamond films has been studied. Uniform polycrystalline diamond films were deposited on 3.0 in. diameter silicon substrates in a microwave plasma chemical vapor deposition (MPCVD) system. The effects of CH4/H2 ratio, pressure, and power variation on film stress were investigated. The macro‐stress, or uniform stress, in the films was measured using the X‐ray diffraction (XRD) d‐sin2ψ technique. In general, 〈220〉‐oriented films exhibited tensile stress and 〈111〉‐oriented films were in compression. The micro‐stress, or non‐uniform stress, calculated from diffraction peak broadening, was observed to be tensile for all samples. Films of relatively small grain size and 〈220〉 orientation showed both the highest micro‐stress and the highest macro‐stress. Film morphology was analyzed using scanning electron microscopy (SEM) and atomic force microscopy (AFM), while the film texture was studied using XRD. Significant non‐diamond carbon was incorporated in 〈220〉‐oriented diamond as estimated from the intensity of the broad 1580 cm−1 peak in the Raman spectra. Much less non‐diamond carbon was detected in 〈111〉‐oriented diamond films. Good correlation between film morphology and measured stress was observed.
Plasma Polymer Films for Dropwise Condensation of Steam
Authors: Bonnar Mark P. , Burnside Bryce M. , Little Alan , Reuben Robert L. , Wilson John I. B. 
Published: May 2005

AbstractThin hydrophobic polymer films produced by radio frequency (rf) plasma decomposition of hexamethyldisiloxane (HMDSO) have been produced on flat metal (titanium, stainless steel, and copper/nickel) and silicon substrates. By using a statistical design methodology, the deposition conditions have been assessed for their control of the deposition rate, refractive index, water droplet contact angle, and longevity of dropwise condensation of steam. The films showing the best performance were those deposited at the slower rates, using low rf power density and high monomer flow rates, and having the lower refractive indices. There is some dependence on substrate material, with CuNi behaving worst, and titanium providing the best results of the three metals studied. This may be connected with the stability of an interfacial oxide layer. The steam immersion tests have already exceeded 7500 hours of continuous condensation, and many of the films are still producing excellent dropwise condensation. The reasons for these effects of preparation conditions and substrate material on performance are discussed with reference to the plasma chemical process.
Ion‐Beam‐Induced CVD: An Alternative Method of Thin Film Preparation
Authors: Espinós Juan P. , Fernádez Asunción , Caballero Alfonso , Jiménez Victor M. , Sánchez‐López Juan C. , Contreras Leopoldo , Leinen Dietmar , González‐Elipe Agustin R. 
Published: May 2005

AbstractThe ion‐beam‐induced chemical vapor deposition method for the preparation of thin films consists of the bombardment of a suitable substrate with O or N ions of relatively high energy while a flow of an organometallic precursor is directed onto its surface. Single and mixed oxides and nitride thin films can be prepared by this procedure. This paper describes the principles of the method, and presents some examples of thin films prepared with it (TiO2, PbTiO3, AlxTiyOz, AlN, and SnO2). Some characterization results of these thin films by different techniques are reported, with special emphasis on physical and electronic methods such as X‐ray photoelectron spectroscopy (XPS), electron energy loss spectroscopy (EELS), and X‐ray absorption spectroscopy (XAS). Other aspects, such as the preferential removal of C, H, and other impurity atoms from the precursors under the action of oxygen beams, or the possibility of performing lithographic depositions of these dielectric materials, are also considered.
Electrocatalysis and flow detection of alcohols at ruthenium dioxide‐modified electrodes
Authors: Leech Donal , Wang Joseph , Smyth Malcolm R. 
Published: May 2005

AbstractRuthenium dioxide‐(RuO2)‐containing carbon paste electrodes exhibiting electrocatalytic responses toward alcohols are described. The electrocatalytic behavior is exploited for developing a highly stable and sensitive flow‐detection scheme for simple alcohols with a constant‐potential operation (+0.4 V vs. Ag/AgCl). The optimization of the system with respect to variables such as pH, flow rate, operating potential, and RuO2–surface “loading” is reported. The electrode response as stable over 2 weeks with a signal loss of 6%. Repeated injections (60) of methanol over a 120 minute period yielded a relative standard deviation of 3.4%. Detection limits for the various alcohols are dependent on the number and position of the hydroxyl groups, with limits ranging from 30 ng for glycerol to 3 μg for ethanol. Use of these electrodes in liquid chromatography with electrochemical detection is envisaged.
Biocoulometry of cholesterol using porous carbon felt electrodes
Authors: Uchiyama Shunichi , Kato Shinichi , Suzuki Shuichi , Hamamoto Osamu 
Published: May 2005

AbstractFree and total cholesterols in human serum have been determined by controlled‐potential coulometry with porous carbon felt electrodes. In such a coulometric cell, a small amount of sample solution was dropped on the carbon felt dipped into electrolyte containing enzymes and a mediator. Hydrogen peroxide is produced by the enzymatic reaction of cholesterol catalyzed by cholesterol oxidase, and the complete electroreduction of hexacyanoferrate(III) ions [produced by the reaction of hexacynoferrate(II) ions and hydrogen peroxide catalyzed by peroxidase] was carried out under controlled‐potential conditions. In the case of determining total cholesterol in human serum, cholesterol esters were converted to free cholesterol by cholesterol esterase reaction prior to the addition of the sample solution into electrolyte. The conversion ratios of free cholesterol to hydrogen peroxide were found to be 85–89% (RSD < 6%). The electrolysis time of one sample was less than 5 minutes. Immobilization of cholesterol oxidase to the carbon felt surface was attempted; the activity of cholesterol oxidase, Immobilized by the diazo‐coupling method began to decrease 3 days after the immobilization.
Polarographic and voltammetric determination of sodium and tetramethylammonium mercaptoundecahydro‐closo‐dodecaborates
Authors: Jelen F. , Paleček E. , Štrouf O. 
Published: May 2005

AbstractSodium and tetramethylammonium mercaptoundecahydro‐closo‐dodecaborates (used in cancer therapy) produce sparingly soluble compounds with a mercury electrode. These compounds can be determined using differential pulse polarography at the dropping mercury electrode in the concentration range 1.5 × 10−5 to 5 × 10−7 M. Detection limit below 5 × 10−9 M can be attained with stripping voltammetry with relatively short accumulation times. Effects of various conditions are explored. The techniques are suitable for the analysis of pharmaceutical preparations containing mercaptoborate‐S.
Electrocatalytic amperometric detection at polymeric cobalt phthalocyanine electrodes
Authors: Qi Xiaohe , Baldwin Richard P. , Li Huawen , Guarr Thomas F. 
Published: May 2005

AbstractGlassy carbon electrodes modified with a coating of a cobalt phthalocyanine containing polymer offer attractive features for applications as electrocatalytic amperometric sensors following liquid chromatography. These electrodes, which are formed by the anodic electropolymerization of Co‐4,4′,4″,4‴‐tetraaminophthalocyanine, exhibit electrocatalytic properties similar to those of earlier carbon paste electrodes containing Co phthalocyanine monomer added directly to the paste mixture. However, the polymer electrodes also offer increased stability and a compatibility with organic solvents not obtainable with the carbon paste version. The performance of the polymer electrodes is illustrated here for the detection of thiols following reversed‐phase liquid chromatography. Determination of picomole quantities of various thiols is possible at low positive potentials in mobile phases composed of 50% methanol or acetonitrile. Furthermore, the response of the electrodes is extremely stable, with more than 80% of the initial activity retained after 40 hours of continuous use.
Sodium activity measurements in protein solutions with sodium amalgam electrodes
Authors: Gunaratna P. C. , Marinenko G. , Koch W. F. 
Published: May 2005

AbstractA method using sodium amalgam electrodes has been developed to study the effect of protein on activity measurements and residual liquid junction potential of sodium in protein‐containing solutions. It was tested for reliability by application to aqueous sodium chloride solutions before it was applied to protein‐containing solutions. The experimentally determined activity coefficients are in good agreement with the activity coefficients for aqueous sodium chloride solutions reported in literature. Therefore, we used this method to measure the activity of NaCl solutions containing varying concentrations of bovine serum albumin (BSA). The electrode slope of the electrode responses in a protein‐containing medium does not differ from that of pure aqueous solutions. A functional relationship has been established between the concentration of protein and the percent bias in the measurements. Measurements of electromotive force made in protein‐containing solutions do not show any evidence of protein effect on liquid junction potential.
Voltammetric studies of copper(I) and copper(II) with monoamines at the ionic strength of seawater (0.70 M NaClO4)
Authors: dos Santos Margarida M. Correia , Gonçalves M. Lurdes Simões 
Published: May 2005

AbstractThe stabilization of copper(I) by some amines was analyzed by voltammetric methods at the ionic strength of seawater (I = 0.7 M NaClO4). The amines studied were ethylamine, diethylamine, triethylamine, ethanolamine, and 5‐aminopenthanol. Voltammetric methods were used because copper(I) can be produced electrochemically if the ligands in solution stabilize this oxidation state. Differential pulse polarography (DPP) and voltammetry with platinum rotating disk electrodes (RDE) were employed. Because some of the voltammograms were distorted as a result of adsorption problems, adsorption has been studied by ac polarography. For the experimental conditions of negligible adsorption, the stability constants of copper(II) and copper (1) complexes have been determined.
Effect of proteins on the response of anion‐selective electrodes based on vitamin B12 derivatives
Authors: Florido Antonio , Daunert Sylvia , Bachas Leonidas G. 
Published: May 2005

AbstractThe potentiometric response of several polymer membrane based ion‐selective electrodes prepared with hydrophobic vitamin B12 derivatives is described. The effect of different proteins on the properties of these electrodes is discussed. It is suggested that the observed changes in potential upon addition of proteins are due mainly to nonspecific interactions between the proteins and the polymer membrane. Reduction of the nonspecific binding effect is possible by using a polymer matrix that contains free hydroxyl groups. The observed results agree with a theoretical model, which predicts that the nonspecific binding effect is more evident when membranes loaded with relatively small amounts of ionophore are used. The implications of these observations for the development of biosensors are discussed.
Determination of gold using anion‐exchange‐based chemically modified electrodes
Authors: Riley Peter J. , Wallace Cordon G. 
Published: May 2005

AbstractThe determination of gold by the application of electrodes modified with anion exchangers is considered. Particular attention is paid to investigating the capability of these electrodes to determine gold(III) in the presence of copper(II). Electrodes modified with a film of poly(4‐vinyl‐pyridine) or either chemisorbed electrochemically generated were investigated. It was found that copper(II) caused little or no interference in chloride media. However, copper(II) cyanide complexes interfered with the determination of gold cyanide solutions.
Depolarization end point can glassy carbon electrodes: Microscale coulometry of thioglycollic acid
Authors: Jovanović Vladislava M. , Jovanović Momir S. 
Published: May 2005

AbstractAn externally unpolarized twin couple of glassy carbon electrodes, undergoing different pretreatments, and connected to nothing but a recorder, was engaged for simple and fast end‐point detection of electrometric titrations of thioglycollic acid. Microquantities of this substance were determined coulometrically either by its neutralization or by an oxidometric mechanism using the same pair of glassy carbon electrodes in the indicator circuit.
Electrode reactions of nitroxide radicals. IX. Anodic oxidations of 4‐hydroxyimino‐2,2,6,6‐tetramethylpiperidine‐1‐oxyl and 4‐[(aminocarbonyl)‐hydrazone]‐2,2,6,6‐tetramethylpiperidine‐1‐oxyl in water solutions
Authors: de Ilarduya Jose I. Martinez , Krzyczmonik Paweł , Scholl Henryk , Grabowski Grzegorz 
Published: May 2005

AbstractAnodic reactions of two stable nitroxide radicals, 4‐hydroxyimino‐2,2,6,6‐tetramethylpiperidine‐1‐oxyl (1) and 4‐[(aminocarbonyl)‐hydrazone]‐2.2,6,6‐tetramethylpiperidine‐1‐oxyl (2) were studied in aqueous solutions over the pH range 5.33–8.04 using the cyclic voltammetry technique. They show one‐electron oxidation processes of reversible and quasi‐reversible natures, depending on scan rate conditions at pH 5.33. The diffusion coefficients, the observed standard rate constants (ks), and the oxidation potentials for the redox reaction nitroxyl radical ⇌ oxoammonium salt have been determined. A one‐electron transfer process, followed by an irreversible chemical reaction, is observed at pH ≥ 5.71, and the rates of this reaction at pH 5.71 and 6.71 are 0.11 and 0.080 s−1, respectively. Controlled‐potential electrolysis at 0.8 V (vs. SCE) confirms a one‐electron electrode reaction.
Amperometric response of electrodes with porous coating to Gaussian concentration profiles in flowing streams
Authors: Cassidy John , Breen William , Lyons Michael E. G. 
Published: May 2005

AbstractA numerical simulation is performed to calculate the amperometric response for a porous coating on an electrode surface to a Gaussian concentration plug in a flowing stream. The amperometric response is considered as a function of the layer thickness, the diffusion coefficient of the analyte through the layer, and the width of the Gaussian concentration profile. We consider the effect of the first two parameters on the magnitude of the current response and the lag time, which is the time delay between the time at which the peak of the concentration profile reaches the outer edge of the porous layer and the time of the peak current response. However, although it is not possible to decouple the magnitudes of the layer thickness and the diffusion coefficients from experimental measurements, it is possible to determine one parameter if the other is known. The width of the amperometric response varies linearly with that of the incident Gaussian concentration profile.
An automatic system for the measurement of dropping mercury electrode impedances
Authors: Andreu Rafael , González‐Arjona Domingo , Domínguez Manual , Molero Miguel , Roldán Emilio 
Published: May 2005

AbstractA fully automated setup for impedance measurements at the dropping mercury electrode (DME) is described. It is based on the Solartron 1250 frequency response analyzer, and it incorporates an infrared drop‐fall detector. Synchronization with the DME as well as calibration procedures are considered in some detail. Experiments on dummy and electrolytic cells, with and without electroactive species, were performed, and data are compared with earlier results on the same systems.
Preparation and characterization of band nanoelectrodes made of carbonized polyacrylonitrile films
Authors: Wang Joseph , Brennsteiner Albert , Sylwester Alan P. , Renschler Clifford L. 
Published: May 2005

AbstractWe describe the fabrication and characterization of new nanoband electrodes, based on ultrathin carbon films produced by carbonization of deposited polyacrylonitrile. Because of their controlled thickness (down to molecular dimensions) and high electrical conductivity, such electrodes show great promise for electroanalytical work. Sigmoidal voltammograms, characteristic of nonlinear diffusion, are obtained. Direct measurements in electrolyte‐free organic media are illustrated. Effects of band thickness, scan rate, solute and electrolyte concentrations, and other variables are explored. These films and other forms of carbon from polyacrylonitrile present opportunities for a wide range of electrode materials.