bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantitative AES depth profiling of thin oxide films grown on stainless steels and aluminium
Authors: Lorang G. , Xu J. L. , Langeron J.‐P.
Published: December 2004

AES depth profiling was performed in passive overlayers grown on the surface of stainless steels and in alumina films formed on aluminium at 250°C in oxygen. Our quantitative approach is based on the sequential layer sputtering model proposed by Benninghoven and Hofmann for analysis of thin layers (<10 nm). A careful measurement of AES sensitivities in pure standards constituted by metallic elements (for the substrate) and their corresponding normal oxides (for the film) is needed to achieve the necessary conversion of AES sputter profiles into atomic concentration profiles. With the assumptions of (1) an oxide film and a metallic substrate assimilated to two distinct media separated by a step‐like interface and (2) a time‐invariant sputter rate, the method provides an available determination of the film thickness mainly dependent on an appropriate choice for attenuation lengths of Auger electrons. The usual approximations and results should therefore be discussed in the light of the determination of absolute oxygen film contents by means of nuclear reaction analysis (NRA).
Caesium‐ion‐induced Auger emission from aluminium and silicon
Authors: Maydell E. A.
Published: December 2004

Cs+‐induced Auger emission from aluminium and silicon is reported. The atomic‐like features in the spectra are identified and compared with data reported by others for bombardment with noble gas ions. Ion‐induced Auger spectra for aluminium and silicon, measured during the sputter‐etching of an aluminium‐on‐silicon structure, are used to generate dynamic Auger depth profiles for this structure. The ion‐induced Auger profile correlates with an AlCs+ secondary ion enhancement observed in the Cs+ ‐ ion dynamic SIMS depth profile, approaching the Al/Si interface. This AlCs+ enhancement parallels a SiCs+ secondary ion enhancement in the early stages of depth profiling of a fresh silicon surface with a Cs+ ion beam.
Prospects of x‐ray microscopy and x‐ray microtomography for interface studies
Authors: Erre D. , Thomas X. , Mouze D. , Patat J. M. , Trebbia P. , Cazaux J.
Published: December 2004

Microfocal x‐ray projection microscopy allows the non‐destructive investigation of thick specimens with a lateral resolution in the micrometre range. The minimum detectable thickness lies below 100 nm for strongly absorbing materials. For further investigation, x‐ray microtomography leads to three‐dimensional reconstruction of the specimen. Some applications of x‐ray microscopy are connected with the localization and imaging of solid/solid interfaces deeply buried in a matrix. In the future, solid/liquid interfaces and their motion will be of interest. The performance of x‐ray microscopy is discussed and x‐ray projection images obtained with a simple modified scanning electron microscope are shown.
A comparative study of the influence of surface pretreatment on the failure characteristics of adhesively bonded titanium
Authors: Watts J. F. , Dempster B. R.
Published: December 2004

The durability of adhesive joints fabricated from two titanium alloys, commercially pure titanium (TA6) and Ti–6Al–4V (TA10), has been investigated using the wedge cleavage test. Seven different methods of adherend pretreatment were investigated: writ blasting (GB), chromatic acid anodizing (CAA) and sodium hydroxide anodizing (SHA), used alone and with the addiiton of an epoxy primer prior to adhesive bonding. A silane adhesion promoter was also used in conjunction with the grit‐blasted adherend. As expected, the durability depended critically on the substrate pretreatment, with SHA‐treated joints giving the best durability and GB the worst performance. The application of a primer or adhesion promoter tended to improve the situation somewhat. The failure mode was apparently adhesive (interfacial), but when the interfacial failure surfaces were examined by XPS, polymeric residues were identified on the adherend surfaces of all joints. In the case of those joints that exhibited good durability three was evidence of transfer of titanium to the polymer side of the locus of failure. The locus of failure in these cases may be described in terms of a mixed mode failure on a microscale.
Thermal stability and degradation mechanisms of trialkylsilyl surface modifications on silica powder
Authors: Severin J. W. , Van Der Wel H. , Camps I. G. J. , Baken J. M. E. , Vankan J. M. J.
Published: December 2004

The thermal stability of a number of trialkylsilyl surface modifications has been studied. During heating, weight loss is recorded by thermogravimetry, while evolved gases are simultaneously analysed with mass spectrometry. Changes in the molecular structure on the surface are measured with solid state nuclear magnetic resonance (NMR) and static‐SIMS. Degradation mechanisms are proposed and described by a number of reaction equations. The changes in surface chemistry on the internal powder surface as measured with NMR are similar to those observed with static‐SIMS on the outer surface of the powder particles.
Quantitative studies of the initial oxidation stages of FeCrNi alloys using factor analysis and least‐squares fitting methods applied to low‐energy AES spectra
Authors: Steffen H. J. , Hofmann S.
Published: December 2004

The oxidation behaviour of the alloys Fe–19 at.% Cr–9 at.% Ni and Ni–40 at.% Fe–20 at.% Cr was studied in situ at room temperature and oxygen pressures below 10−4 Pa by AES using low‐energy M23VV transitions between 20 and 70 eV. Quantitative determination ofthe relevant components by factor analysis and least‐squares fitting methods enabled a much more detailed analysis of the initial oxidation stages as compared to earlier studies. For all alloy elements, factor analysis revealed the presence of an intermediate chemical state before oxidation which is due to binding with chemisorbed oxygen. Least‐squares fitting with standrd spectra of the pure elements in their metallic, oxidic and intermediate states disclosed the sequential oxidation of Cr, Fe and Ni with increasing oxygen exposure. Preferential oxygen chemisorption on Cr and oxidation of Cr is accompanied by oxygen‐induced segregation and is followed by Fe and Ni oxidation on top of the previously formed oxide for the Ni‐rich alloy. Nickel oxidation is drastically reduced in Fe‐rich alloys. After exposure to 900 L of oxygen, oxidation results in a layered structure as confirmed by AES sputter depth profiles which can be resolved into oxide and pure metal components. Together with the small electron escape depth of only 2–4 atomic layers, this procedure gives well‐resolved depth distributions within the total oxide thickness of ∼6–7 monolayers for NiFe40Cr20 and 11–12 monolayers for FeCr19Ni9.
Methods of electron spectra processing based on solving the transport equation of electron motion in a solid
Authors: Borodyansky S.
Published: December 2004

Within the transport approximation, the problem of the elastic and inelastic scattering of Auger electrons, photoelectrons and backscattered electrons is investigated. The use of an invariant‐embedding approach allows the derivation of analytical expressions for the path length distribution for both emitted and backscattered electrons. These functions are used to produce a new procedure for background subtraction in AES/XPS and to develop a technique of REELS processing to reconstruct both the electron differential energy loss cross‐section in a solid and the ratio λi/λtr, where λi is the inelastic mean free path and λtr is the transport path for elastic scattering.
Reference samples for depth profiling: Highly accurate calibration of implanted ion dose by neutron activation analysis
Authors: Garten R. P. H. , Bubert H. , Palmetshofer L.
Published: December 2004

To prepare a candidate reference material for depth‐profiling analysis by AES, XPS, SIMS, SNMS, ISS, RBS, etc., silicon wafers were implanted with cobalt ions at an energy Eo = 300 keV. The total implanted doses, 1012 <D <1017 Co ions cm−2, were determined by instrumental neutron activation analysis (INAA) within a dynamic range of five decades. A high accuracy of better than 1.5% was attained. This is considered to be adequate for reference materials dedicated to depth‐profiling analysis by AES, XPS, SIMS, SNMS, ISS and RBS. INAA can offer the determination of 14 prominent elements, to be implanted in high‐purity materials, with limits of detection DLD <109 ions cm−2.
Validity of background correction algorithms studied by comparison with theory of synchrotron‐radiation‐excited core levels and their corresponding auger peak intensities
Authors: Jansson C. , Hansen H. S. , Jung C. , Braun W. , Tougaard S.
Published: December 2004

The validity of the Shirley, the straight line and the Tougaard methods for background correction of electron spectra is studied under variation of the photon energy by using a synchrotron light source. For C and Ag the intensity ratio of the peak from a photon‐excited core level and the corresponding Auger transition is compared with theory. This ratio is independent of the possible error in photo‐ionization cross‐sections. The deviations are found to increase with increasing photon energy. Possible explanations are discussed in terms of errors in the elastic mean free path and energy dependence of the analyser response function as well as the characteristics of the monochromator. The agreement between theoretical and experimental ratios is better for the Shirley method than for the straight line method and significantly best for the Tougaard method.
Electromigration of metallic islands on Si(001) surface
Authors: Ichinokawa T. , Iizumi H. , Haginoya C.
Published: December 2004

Electromigration of metallic islands formed by vapour deposition on the Si(001) 2 × 1 surface has been investigated by an ultrahigh vacuum scanning electron microscope (UHV‐SEM) at temperatures higher than the melting points of the islands with heating by passing dc current through the Si substrate. The direction of the island migration depends on the kind of metal. The speed is approximately proportional to the island radius and increases exponentially with temperature. The activation energy for migration of Au islands is 0.6 eV. The driving force of the island migration is discussed.
Development of a hyperthermal oxygen‐atom generator
Authors: Hoflund Gar B. , Davidson Mark R. , Outlaw R. A.
Published: December 2004

A source that is compact, durable and mounts on a standard standard ultrahigh vacuum (UHV) flange has been developed for the generation of hyperthermal oxygen atoms. In this source oxygen atoms permeate through an Ag membrane held at 500°C and are then emitted toward the target from the vacuum side of the membrane by electron‐stimulated desorption. The current prototype model generates useable O‐atom fluxes of ∼1012 atoms cm−2 s−1, and future modifications should increase this flux by 1–3 orders of magnitude. Based on the O+ energy distribution, the average O neutral energy is ∼5 eV with a fairly broad distribution (full width at half‐maximum ∼3.6 eV). The information required for the development of this source and the design of the source are prsented.
Oxidation in preparation of oxide superconducting films by MBE using NO2 and O3 gases
Authors: Nonaka H. , Shimizu T. , Hosokawa S. , Ichimura S. , Arai K.
Published: December 2004

In order to prepare oxide superconducting films by molecular beam epitaxy (MBE), we developed a compact NO2 supersonic molecular beam source and a new ozone jet generator to supply oxidizing gases with high controllability. Using these sources, oxide superconducting films of REBa2Cu3Ox (RE  Nd, Y) were prepared on either MgO or SrTiO3 substrates. Because of the sufficiently low pressure during deposition, the oxidation process of the metals, especially of copper, by the oxidizing gases and the crystallization and surface flatness of the films were studied in situ by XPS and reflection high‐energy electron diffraction (RHEED) together with effective cleaning of the substrates by the oxidizing gases.
Characterization of AlGaAs/GaAs interfaces by EELS and high‐resolution Z‐contrast imaging in scanning transmission electron microscopy (STEM)
Authors: Lakner H. , Maywald M. , Balk L. J. , Kubalek E.
Published: December 2004

Recent developments in scannning transmission electron microscopy (STEM) instrumentation have pushed the limits of the achievable spatial resolution for analytical measurements into the subnanometer regime, which is necessary for the characterization of semiconducting heterostructures and interfaces. Z‐Contrast (or high‐angle annular dark field) imaging combines atomic resolution with chemical contrast. Such images are not affected by contrast reversals due to objective lens defocus or changes in specimen thickness, such as phase contrast images (bright field images). Parallel detection of electron energy‐loss spectra allows spatially resolved quantitative chemical information to be obtained even for high energy losses and when using a very fine electron probe diameter (down to < 0.3 nm). Examples demonstrating the performance of these techniques are given for AlGaAs/GaAs heterostructures used for very high speed and very high frequency devices. While high‐resolution Z‐contrast imaging is superior with respect to the spatial resolution achieved and the acquisition time needed, electron energy‐loss spectroscopy (EELS) can be used to record chemical line profiles with slightly decreased spatial resolution. In particular it can be used to quantify the Z‐contrast images by means of point analysis. Thus, the combination of Z‐contrast imaging and EELS can give information beyond the scope of either individual characterization technique.
Characterization of chromatized hot‐dip‐galvanized steel and 55% AlZn‐coated steel using ESCA and AES
Authors: Nilsson J.‐O. , Hörnström S.‐E. , Hedlund E. , Klang H. , Uvdal K.
Published: December 2004

Chromating of metals has been used for a long time as corrosion protection. In this study two commercial products for chromating, one based on chromates (Iridite 9L‐6) and one with an addition of a polymer (Okem Coat F1), have been analysed on hot‐dip‐galvanized steel, 55% AlZn‐coated steel and pure Zn, Al and Au. The analysis techniques used for this study were electron spectroscopy for chemical analysis and scanning Auger microscopy. With these methods it has been possible to characterize binding energies of different compounds in chromating coatings and to record elemental maps and depth profiles. Coatings formed in the laboratory have been compared with those from production lines. Comparisons of Cr6+/Cr3+ ratios of the chromating coatings formed on different substrates revealed that Cr6+ in a thin coating on Zn is almost completely reduced to Cr3+, while on Al the reducton of Cr6+ is very limited. On hot‐dip‐galvanized steel the Cr6+/Cr3+ ratio is higher than on 55% AlZn‐coated steel. This can be explained by differences in chromate coating thicknesses on hot‐dip‐galvanized and 55% AlZn‐coated steel. The coating formed by Iridite 9L‐6 on 55% AlZn‐coated steel is preferentially found in the interdendritic areas. Okem Coat F1 forms a slightly more homogeneous chromium coating on 55% AlZn‐coated steel as compared to that of Iridite 9L‐6. On the basis of the aqueous chemistry of chromium compounds, models are discussed for the formation of the chromating coatings.
XPS and AES studies of carbon steel polarized in aqueous molybdate solutions
Authors: Pan F.‐M. , Lin Y.‐L. , Oung J.‐C.
Published: December 2004

X‐ray photoemission spectroscopy (XPS) and Auger electron spectroscopy (AES) have been used to study the passive film on carbon steel produced electrochemically in aerated and deaerated molybdate aqueous solutions. Very few molybdate ions were adsorbed on the oxide surface of the carbon steel in aerated solution according to XPS measurements. On the contrary, significant amounts of Mo(+4), Mo(+5) and Mo(+6) ions were detected on the anodically polarized steel in deaerated solution. In addition to molybdate ions and iron oxides, MoO(OH)2 and Mo2O5 were suggested to be present in the opaque passive film.
ESCA study of the oxidation of DHP copper
Authors: Pedocchi L. , Billi A. , Marinelli E. , Wu J. X. , Rovida G.
Published: December 2004

The surface composition of deoxidized high phosphorus (DHP) copper sheets was investigated by ESCA with the aim of verifying the role of phosphorus in oxide formation. While no surface segregation of phosphorus was observed on samples cleaned by ion bombardment and annealing in ultrahigh vacuum, the presence of large amounts of phosphorus was found after the formation of the oxide by exposure to 0.1 Torr oxygen at 770 K. The surface enrichment in P with the same binding energy was found after annealing a sheet of DHP copper coated with a layer of Cu2O deposited by sputtering. The binding energy of the P 2p peak as well as the analysis of the components of O 1s can be interpreted with the formation of a metaphosphate. Experiments performed at intermediate temperatures showed that the segregation of phosphorus is appreciable above 600 K and appears to be related to oxygen diffusion into the bulk.
Monte‐Carlo simulations of the point‐to‐point resolution in scanning Auger microscopy and x‐ray microanalysis of thin overlayers
Authors: Valamontes E. , Nassiopoulos A. G. , Glezos N.
Published: December 2004

The point‐to‐point resolution of Auger electron spectroscopy is compared to that of x‐ray microanalysis of thin unsupported films and of thin films on a bulk material. Monte‐Carlo calculations are used in this respect. The incident beam is a Gaussian‐distributed curve with standard deviation σo = 40 Å and an energy range 10–100 keV. A Point‐Spread‐Function describing the radial distribution of the analysed signal is, in each case, determined from the Monte‐Carlo results. From this function and by using the Rayleigh criterion, the point‐to‐point resolution is calculated.
Electron energy loss spectroscopy (EELS) and electron spectroscopic imaging (ESI) for the localization of titanium in chrysotile asbestos
Authors: Berghmans P. A. , Adams F. C.
Published: December 2004

High spatial resolution and sensitivity make electron energy loss spectroscopy (EELS) and electron spectroscopic imaging (ESI) excellent techniques for localizing low levels of titanium (∼2 wt.%) in ultrastructural features as small as cross‐sections of chemically modified chrysotile asbestos fibres (i.e. 20 nm diameter). Visible beam damage, i.e. mass loss and morphological changes, was drastically reduced when a Zeiss EM 902 fitted with a cryoholder was used to perform ESI using the three‐window background extrapolation method. The electron micrographs revealed that the titanium distribution is located not only at the external surface of the fibre but also inside the fibril tube.
XPS studies on intermetallic phases formed in AlNi and AlMn thin films
Authors: Bertóti I. , Mohai M. , Csanády A. , Barna P. B. , Berek H.
Published: December 2004

Thin films of AlNi and AlMn alloys were prepared by high‐temperature successive vapour deposition (HTSVD). In the case of AlNi a pronounced shift (∼0.5 eV) of the Ni Auger parameter [combined Ni 2p binding energy (BE) and Ni L3 VV kinetic energy (KE) values] to lower values can be detected for the Al3Ni compound, the structure of which was determined by x‐ray diffraction. In the AlMn system a quasi‐crystalline Al4Mn phase was formed and its structure was determined by selected area electron diffraction as well as by TEM and cross‐sectional TEM. XPS measurements show that for this AlMn phase only a small peak shift (∼0.3 eV) of the Mn 2p core level can be related to the compound formation as compared to the pure metallic state of the components. The same shift to lower values was also obtained for the Auger parameter (Mn 2p BE + Mn L3M23M23). The small peak observed by others at 2.4 eV higher than the Al 2p BE is unambiguously related to the oxygen content in our samples. On the basis of the results we can conclude that the observed core level and Auger line shifts; the small linewidths and especially the Auger parameter shift to lower values are all indicative of the formation of intermetallic compounds in these systems.
XPS and UPS of Pt catalysts of different preparation
Authors: Paál Z. , Schlögl R.
Published: December 2004

The techniques of XPS and UPS measurements with Pt black catalysts as well as reasonable data processing are discussed. The surface of Pt contains carbon and oxygen impurities in amounts of 15%–20% each. The use of various sensitivity factors does not influence the conclusions drawn on purity. Oxygen 1s and C 1s line fitting has been done on a self‐consistent basis. Of various chemical O and C species, three‐dimensional carbon islands and water and/or H2O attached to Pt sites predominate. These latter entities are well detected also by UPS. The usefulness of difference XP and UP spectra in distinguishing chemical entities is pointed out.
Internal scattering of electrons in a hemispherical spectrometer
Authors: Greenwood J. C. , Prutton M. , Roberts R. H. , Liu Zhixiong
Published: December 2004

Seah and Smith have reported a method of measuring the peak‐to‐background ratio below the silver LMM Auger peak as a function of the pass energy of a hemispherical electron spectrometer. They used this measurement to reveal the extent of a contribution to the observed spectrum due to secondary electrons generated at the outer hemisphere near to its exit plane. This scattering is caused by electrons whose kinetic energies are just above those passing round the central trajectories of the spectrometer. The work reported here extends this method to a range of kinetic energies and reveals a varying contribution of the internal scattering to the shape of the measured spectrum across the energy span 50–2500 eV. This has an important effect upon attempts to measure the true shape of the background of a spectrum and the manner in which it depends, for example, upon the atomic number of the sample.

Calibration methods are presented for the evaluation of the internal scattering of the spectrometer with the objective of finding ways to remove it from the measured spectrum. With the aid of electron optical modelling, the origin of the internal scattering is attributed both to electrons with energies just above those passed by the spectrometer that strike the outer hemisphere and to very energetic electrons leaving the sample and striking surfaces inside the transfer lens between the sample and the hemispheres. These methods are applied to a number of spectra of pure elements to demonstrate the efficacy of the procedure.
SIMS analysis of oxygen in AlxGa1 − xAs alloys: Variations in sensitivity as a function of alloy composition
Authors: Chew A. , Sykes D. E. , Houlton M. R. , Blackmore G. W. , Blunt R. T.
Published: December 2004

The variation in the SIMS sensitivity factor for oxygen in the AlxGa1 − xAs alloy system has been investigated as a function of alloy composition using ion‐implanted reference sample. Oxygen doses of 5 × 1014, 1 × 1015 and 5 × 1015 atoms cm−2 have been implanted in a range of alloy compositions (x = 0.07, 0.22, 0.33, 0.37, 0.60 and 0.80). The results are presented as a calibration referenced to GaAs to allow interpolation for other alloy compositions and without unnecessary duplication of reference sets. The results show no significant variation in sensitivity factor for oxygen relative to arsenic and this is confirmed by analysis of an implant into a GaAs‐on‐AlGaAs layer structure.
Time‐of‐flight secondary ion mass spectrometric analysis of polymer surfaces and additives
Authors: Linton R. W. , Mawn M. P. , Belu A. M. , DeSimone J. M. , Hunt M. O. , Menceloglu Y. Z. , Cramer H. G. , Benninghoven A.
Published: December 2004

This paper presents the application of static time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) to the analysis of polymeric materials, including chemically modified polymers and polymer additives. Throuh the detection of intact functionalized oligomers, analysis of poly(styrene) functionalized with perfluoroalkyl chlorosilane provides confirmation of a successful endgroup termination for a living polymerization. The calculated molecular weight distribution also is in good agreement with chromatrographic results. High mass resolution studies allow monitoring of the hydrogenation of a poly(butadiene) polymer through increases in oligomer mass due to proton addition. The quantitative ToF‐SIMS results for the extent of hydrogenation for a specific oligomer are lower than the values averaged over all oligomers as determined by magnetic resonance. The usefulness of ToF‐SIMS for determination of trace‐level polymer additives is demonstrated for linear low‐density poly(ethylene) (LLDPE). Application of a 150 nm thick evaporated Ag pattern enables in situ detection of the five trace additives present in the LLDPE matrix, and also provides information on additive surface migration and surface oxidation. A study of the silver cationization process for the silver‐patterned LLDPE surface suggests differences in diffusion and/or ionization processes for two additives. This is confirmed with mass‐resolved ion imaging to show the lateral distribution of the silver‐cationized signals for various polymer additive molecular ions. Finally, poly(styrene) (Mn = 1300) coated with a continuous silver overlayer is investigated. The ToF‐SIMS‐determined molecular weight distribution shifts to lower masses, suggesting the greater diffusion of shorter polymer chains through the silver overlayer.
SIMS imaging of insulator surfaces
Authors: van der Heide P. A. W. , McIntyre N. S.
Published: December 2004

Imaging of secondary ions emitted from bare insulator surfaces has been carried out on a Cameca IMS 3F secondary ion mass spectrometer without the use of electron beam, conductive grid or coating methods. This was accomplished by analysing secondary ions with kinetic energies ranging from 200 to 350 eV emitted from chargestablized samples. Charge stabilization was attained by placing the sample under various forms of specimen isolation. Images from both O− and Cs+ primary ion‐bombarded surfaces were collected, with several examples shown; O− provided the better spatial resolution due to improved sample potential stability. Mechanisms associated with charge stabilization and image distortion are elaborated upon with the aid of computer simulations.
Molecular photofragmentation during non‐resonant multiphoton ionization of sputtered species
Authors: Coon S. R. , Calaway W. F. , Pellin M. J. , Burnett J. W. , White J. M.
Published: December 2004

To assess the quantitative analytical capabilities of laser post‐ionization of sputtered neutrals, the photoionization of sputtered Cu, Al and Ru atoms and clusters was investigated. By measuring velocity distributions using both resonant and non‐resonant photoionization of the atoms and one‐photon and two‐photon ionization of the clusters, photogragmentation of clusters was found to be significant. Atomic velocity distributions measured using non‐resonant ionization peaked at the same velocity as the respective dimer distribution, indicating that the majority of the non‐resonant atomic ion signal is from photogragmented dimers. The contribution to the dimer ion signal from photogragmentation of the trimer varied with the two‐photon laser power density. Domination of the atomic photoion channel by molecule fragmentation appears to be a general phenomenon that must be accounted for in all gas‐phase multiphoton non‐resonant ionization experiments at easily achievable laser power densities (≤ 108 W cm−2). To minize photogragmentation effects, atoms should be ionized resonantly and clusters should be onephoton ionized.
The effect of polymer architecture on the SIMS spectra of glycolide/trimethylene carbonate copolymers
Authors: Brinen J. S. , Rosati L. , Chakel J. , Lindley P.
Published: December 2004

Copolymers of glycolide and trimethylene carbonate having the same nominal composition but varying in copolymer architecture have been studied by static quadrupole SIMS, time‐of‐flight SIMS and by ESCA. The surface composition of melt‐pressed films were found to vary markedly with the polymer architecture. Time‐of‐flight SIMS spectra clearly showed spectral differences which can be related to the glycolic acid block length.
Influence of bath additives on the composition of electrodeposited silver coatings
Authors: Ashiru O. A.
Published: December 2004

Several thin‐film analysis techniques (energy‐dispersive x‐ray analysis and Auger, Rutherford backscattering and non‐resonance (d,p) reactions) were used to assess the level of impurities incorporated during silver deposition in the presence and absence of additives. The study showed that the elemental constituents of the more strongly absorbed additives, i.e. brighteners, were incorporated with the silver deposits. The levelling agents are less strongly absorbed and thus their constituents were not appreciably incorporated with the silver deposits.
Quantitative evaluation of titanium nitrides in the presence of carbon and oxygen contaminants using the Ti L3M23V Auger transition
Authors: Lascovich Juan C.
Published: December 2004

A method for quantitative compositional analysis of both Ti and N, as well as the content of the frequent carbon and oxygen contaminants for titanium nitrides, has been proposed using the Ti L3M23V Auger structure. Samples with different elemental compositions were obtained by N2+ and Ar+ bombardment of metallic titanium. Monitoring simultaneously the XPS spectra and x‐ray ‐excited Ti L3M23V Auger transition, the latter being resolved into its inter‐ and intra‐ atomic Auger components, a linear dependence between the area fraction corresponding to the intra‐atomic component and the atomic titanium fraction was found. From analysis of experimental data, the ratio between the area of the intra‐atomic Auger component and the integrated intensity of the Ti 2p photoemission doublet was assumed to be linear function of the titanium fraction. From these relations, atomic fractions of Ti, N, O and C are determined using only Auger features in combination with the oxygen and carbon signals. The results obtained by this method are in good agreement with XPS values in the analysed range (40% < Ti < 80%; N < 60%; C < 25%; O < 15%).
UV stabilizers: Their effects on vinyl compounds
Authors: Reid W. J.
Published: December 2004

Poly(vinyl chloride) (PVC) is the polymer of choice in a wide variety of applications on account of its comparatively low cost, high chemical resistance, good mechanical properties and electrical insulating capabilities. The even wider application of the material has been restricted by its low thermal and photolytic stability. This paper reviews the various light degradation and stabilization mechanisms that have been postulated recently for PVC. The importance of the thermal stabilizer system to the photostabilization of the material is also stressed. Finally the market opportunity for a cost effective UV stabilizer system for rigid PVC is discussed emphasizing the versatility that such a product would give to the vinyl siding manufacturer.
Rheology of poly(vinyl chloride) dry blends I. A fusion model for evaluating rigid dry blend compound performance
Authors: Wingrave James A. , Peden Montgomery C.
Published: December 2004

This study of rigid poly(vinyl chloride) (PVC) dry blend fusion proceeds via scanning electron microscope (SEM) examination of material in a sigma mixing bowl fitted torque rheometer. A mathematical model is developed and tested. During the course of the study, degradation behavior was observed some time before the conventional t2 or the end point of thermal stability. A suitable model for torque changes during degradation was not developed.
Smoke suppressants for plasticized poly(vinyl chloride)
Authors: Desai Harshad P. , Deanin Rudolph D.
Published: December 2004

Addition of plasticizers to poly(vinyl chloride) generally increases its flammability and frequently increases smoke production during its burning. Flame retardants added to plasticized PVC can reduce flammability, but increase smoke production. This study shows that proper choice of combined use of other polymers, phosphate plasticizers, fillers and other flame retardants, produces measured synergistic improvements in flame retardance and smoke suppression which could benefit applications such as PVC wire and cable insulation.
The advantages of one pack additive packages in PVC processing
Authors: Holsopple Peggy S.
Published: December 2004

With the push towards higher production rates and tighter SPC/SQC in the PVC industry today, the disadvantages of having many microingredients in a formulation become readily apparent, especially to the plant personnel who have to deal with the weighting and blending of these microingredients. The concept of adding microingredients in a “one pack” form has been explored in the past using lubricant/stabilizer combinations designed to eliminate some of the problems inherent in adding a liquid stabilizer. This paper explores the concept of a one pack system consisting of impact modifier, process aid, calcium stearate, and stabilizer. Advantages of such a one pack combination are discussed in relation to formulation, blending, materials handling, and processing.
Mixed metal vinyl stabilizer synergism. IV: Antimony mercaptide/group II metal carboxylate blends
Authors: Grossman Richard F.
Published: December 2004

The reaction of a model compound for degrading PVC, cinnamyl chloride, with blends of antimony tris(isooctyl thioglycolate) and calcium octoate yields primarily calcium chloride and cinnamyl octoate. This is in contrast to typical mixed metal systems where ligands exchange, and also to lead octoate/calcium octoate blends, where lead chloride is formed under the same conditions. In rigid PVC, it is likely that antimony mercaptides function as stabilizers mainly by acting as phase transfer catalysts for calcium stearate.
Mixed metal vinyl stabilizer synergism. V: Dehydrochlorinations reactions of model compounds
Authors: Grossman Richard F.
Published: December 2004

The capture of HCl from cumyl chloride, a model compound for degrading PVC, by epoxidized soybean oil, yielding the related chlorohydrin, is relatively inefficient. The reaction is much accelerated by the presence of metal salts that are primary stabilizers, in particular by zinc carboxylates. In such instances, the initial reaction product is not the chlorohydrin, but the corresponding alphahydroxy ester and metal chloride. Such metal salts, however, also strongly catalyze the rate of loss of HCl from the model compound. Mixed metal blends are found to accelerate the reaction of liberated HCl with epoxy compounds with, on the other hand, only slight catalysis of the dehydrochlorination reaction, and with formation of the secondary metal chloride.
Upper critical solution temperature lubricants for CPVC
Authors: Nakamura H. , Fukuoka T. , Uesaka T.
Published: December 2004

Chlorinated polyvinyl chloride (CPVC) is often used in injection molding for products that demand high heat resistance. However, proper control of its flow properties is difficult. To improve flow behavior some internal lubricants are usually used, but they reduce heat resistance of the products. Upper critical solution temperature (UCST) lubricants were found to enhance its flow properties, and also high heat resistance was retained. They act as internal lubricants during processing, improving flow and phase separation during cooling. Therefore they are present essentially as inert filler and thus have little effect on heat distortion temperature.
Experimental design for non‐statisticians
Authors: Neuman Richard C.
Published: December 2004

Many of us were taught that if more than one variable were changed at a time, the cause of some end result could never be determined. This is certainly true if the experiment is not planned to accommodate analysis of the data. The complex problems faced by modern scientists and engineers can not be solved efficiently using one‐at‐a‐time methods. Good experimental design promotes broader exploration of the variables studied, produces more results from fewer experiments, and validates results by comparing them against measured experimental error. This is done by deliberately varying all variables from run‐to‐run in systematic patterns. Timely product development and problems solving bears directly on profitability. A systematic approach can pay handsome dividends. The basis of good experimental design and several simple designs for everyday use are presented.
Efficacy and tolerability of prophylactic treatment with intravenous piperacillin/tazobactam in patients undergoing hematopoietic stem cell transplantation
Authors: Kroschinsky F. , Wichmann G. , Bornhauser M. , Ordemann R. , Schuler U. , Ehninger G. , Hanel M.
Published: December 2004

Abstract: Background. Infections remain a major cause of morbidity and mortality in patients undergoing autologous or allogeneic hematopoietic stem cell transplantation (HSCT). About 80% of patients experience fever during aplasia and early engraftment despite oral antibacterial chemoprophylaxis. Methods. In a pilot study, 50 patients undergoing autologous or allogeneic HSCT received a prophylactic antibacterial treatment with intravenous piperacillin/tazobactam beginning on day of stem cell or bone marrow transfusion. They were analyzed retrospectively for frequencies of fever of unknown origin (FUO), documented infection, bacteremia and death because of infection. Furthermore, data from microbiological monitoring and tolerability were evaluated. Results. Among 28 autologous transplanted patients, 10 (36%) developed fever more than 38.5 °C; 9/10 FUO, 1/28 pulmonary infiltrates. Eighteen patients (64%) remained without any symptom of infection. In the allogeneic group (n = 22), there were eight patients (36%) with FUO, and five patients (23%) with documented infections (pneumonia 2, enteritis 1, pyelonephritis 1, Escherichia coli bacteremia 1). In nine patients (41%), escalation of antimicrobial treatment was not necessary. The majority of detected microbes in cultures of throat and nose secretions, blood, urine and stool were gram‐positive bacteria (77.8%), among them Staphylococcus epidermidis (23.5%), streptococci (group A, B, C; 21.0%) and enterococci (10.6%). Incidence of gram‐negative bacteria and fungi was similar with 11.8% and 10.4%, respectively. The most frequent gram‐negative strains were Escherichia coli (6.5%) and Pseudomonas aeruginosa (1.7%). There was no severe toxicity or hypersensitivity. Conclusion. Compared to oral decontamination and chemoprophylaxis, an intravenous prophylactic regimen as described above could be an effective and well‐tolerated approach in prevention of bacterial infections and related complications, with a higher acceptance in recipients of bone marrow or stems cell grafts. Further evaluation in comparison with fluoroquinolone prophylaxis regarding efficacy, development of resistances as well as cost‐benefit analyses is warranted.
Transmission of viral hepatitis by kidney transplantation: donor evaluation and transplant policies (Part 1: hepatitis B virus)
Authors: Natov S.N. , Pereira B.J.G.
Published: December 2004

Abstract: This two‐part article discusses serologic testing of prospective donors for viral hepatitis B and C as part of the comprehensive donor evaluation and reviews of the current policies and practices aimed at preventing donor‐to‐recipient transmission of hepatitis B and C viruses (HBV, HBC). This second part of the review discusses HCV. Organs procured from HCV‐infected donors can transmit the virus to their recipients. Because a number of studies have associated infections with HCV with increased morbidity and mortality among renal transplant recipients, it is important to prevent HCV transmission with renal transplantation. The majority of organ procurement organizations (OPOs) perform routine screening of organ donors for antibodies to HCV (anti‐HCV). The prevalence of HCV infection among cadaver organ donors, ascertained based on a positive anti‐HCV test by ELISA2, varies worldwide between 1.08% and 11.8%. The use of kidneys from donors negative for anti‐HCV by ELISA2 carries negligible or no risk of transmitting HCV infection. The use of organs from anti‐HCV‐positive donors has been restricted to life‐saving transplants (heart, liver or lung) by the majority of OPOs worldwide. However, discarding kidneys from all anti‐HCV positive donors would lead to unnecessary waste of organs because not all anti‐HCV positive donors are infectious. Recently, the policy of unconditional restriction on the use of kidneys from anti‐HCV positive donors has been challenged, and transplantation of organs from anti‐HCV‐positive donors into anti‐HCV‐positive recipients has been found to be safe. An even better alternative might be a policy of transplanting kidneys from anti‐HCV‐positive donors only in HCV RNA‐positive recipients. However, until more data become available, these two strategies remain experimental treatments.
Characterization of human killer cell reactivity against porcine target cells: differential modulation by cytokines
Authors: Horvath‐Arcidiacono Judith A. , Bloom Eda T.
Published: December 2004

Abstract: The cytotoxic cell response to porcine cells by human lymphocytes, and the modulation of cytolytic cellular activity by human cytokines were investigated. Human peripheral blood mononuclear cells (PBMC) and purified lymphocyte subsets were co‐cultured with fresh irradiated porcine stimulator cells and examined for the development of lytic activity and for their proliferative response. Porcine target cells included a new cell line, MS‐PBMC‐J2 (designated J2; SLA‐DR+MHC class I+CD2+CD3–CD8+CD16+CD45+), aortic and microvascular endothelial cells. Initial results showed that natural killer (NK) cells were fivefold more efficient in killing porcine target cells compared with T cells. IL‐12 augmented the killing of porcine target cells by human NK cells beyond that induced by stimulation with cells alone. In contrast, IL‐2 and IL‐15 often induced substantial human NK cell mediated killing of porcine target cells, including endothelial cells in the case of IL‐2 where such targets were examined, even in the absence of stimulator cells. Finally, neither IL‐18 nor IL‐8 had any effect beyond background on NK cell mediated killing of porcine target cells. These findings show that cytokines that would be produced in a xenograft setting clearly modulate the ability of human cytolytic cells to kill porcine targets. In addition, fresh unstimulated human NK cells lysed J2 and porcine aortic endothelial cells, but not porcine microvascular endothelial cells, suggesting the possibility of rapid attack of xenografts by NK cells, and differential susceptibility of endothelial cells from different vascular structures to this attack.
Estimators for particulate sampling derived from a multinomial distribution
Authors: Geelhoed B. , Glass H. J.
Published: December 2004

Counting the number of units is not always practical during the sampling of particulate materials: it is often much easier to sample a fixed volume or fixed mass of particles. Hence, a class of sampling designs is proposed which leads to samples that have approximately a constant mass or a constant volume. For these sampling designs, estimators were derived which are a ratio of arbitrary sample totals. A Taylor expansion was used to obtain a first‐order approximation for the expected value and variance in the limit of a large batch‐to‐sample size ratio. Furthermore, a π‐estimator for a ratio of batch totals was found by deriving expressions for the first‐ and second‐order inclusion probabilities. Practical application of the π‐estimator is limited because it requires inaccessible batch information. However, when the denominator of the estimated batch ratio is the batch size, the π‐estimator becomes equal to a sample total divided by the sample size in the limit of a large sample‐to‐particle size ratio. As a consequence, the obtained sample ratio becomes an unbiased estimator for the corresponding batch ratio. Retaining unbiasedness, the Horvitz–Thompson estimator for the variance, which also contains inaccessible batch information, is replaced by an estimator containing sample information only. Practical application of this estimator is illustrated for the sampling of slag, produced during the production of steel.
Finite sample properties for the semiparametric estimation of the intercept of a censored regression model
Authors: Schafgans Marcia M. A.
Published: December 2004

Financial support for this paper was provided by a C.A. Anderson Fellowship of the Cowles Foundation. I wish to thank Donald Andrews, Moshe Buchinsky, Oliver Linton, and Peter Robinson for helpful discussions. I also wish to thank three anonymous referees for their comments and suggestions. I am, of course, responsible for any remaining errors. A popular two‐step estimator of the intercept of a censored regression model is compared with consistent asymptotically normal semiparametric alternatives. Using a root mean squared error criterion, the semiparametric estimators perform better for a range of bandwidth parameter choices for a variety of distributions of the errors and regressors. For error distributions that are close to the normal, however, the two‐step parametric estimator performs better.
A continuous mapping theorem for the argmax‐functional in the non‐unique case
Authors: Ferger Dietmar
Published: December 2004

The Argmax‐Continuous Mapping Theorem (Argmax‐CMT) of Kim and Pollard resp. van derVaart and Wellner has been proved to be a very useful tool in statistics for deriving distributional convergence of M‐estimators. However it only works as long as the limit process possesses an almost sure unique maximizing point. In this article we prove an extension of the Argmax‐CMT where almost sure uniqueness is no longer needed. Moreover our Argmax‐CMT is also valid in the function space D(ℝ) equipped with Lindvall’s version of the Skorokhod‐topology. As an example the result is applied to change‐point estimators.
CD177 polymorphisms: correlation between high‐frequency single nucleotide polymorphisms and neutrophil surface protein expression
Authors: Caruccio Lorraine , Walkovich Kelly , Bettinotti Maria , Schuller Randy , Stroncek David
Published: December 2004

BACKGROUND:  Human neutrophil antigen‐2a (NB1) is located on NB1 glycoprotein, which is expressed on subpopulations of neutrophils. PRV‐1 is a gene that is over‐expressed in neutrophils from patients with polycythemia rubra vera. The gene encoding NB1 differs from PRV‐1 at four nucleotides. The purpose of this study was to determine if PRV‐1 and NB1 are alleles of the same gene or two separate genes; and, moreover, if they are alleles, to explore potential correlations to NB1 glycoprotein expression.

STUDY DESIGN AND METHODS:  Primer pairs were used to amplify WBC DNA in the regions surrounding the four NB1 polymorphic sites. The four resulting amplicons were sequenced. The size of the neutrophil population in each donor that stained brightly with CD177 antibody was assessed by flow cytometry.

RESULTS:  If PRV‐1 and NB1 are separate genes, then all people should be heterozygous for the PRV‐1/NB1 polymorphisms. Because 11 of 23 donors were homozygous for PRV‐1 polymorphisms at all four sites, PRV‐1 and NB1 are alleles of the same gene, CD177. When the sequenced exons were compared with PRV‐1, 13 single nucleotide polymorphisms (SNPs) that result in amino acid changes were found. The G42C NB1 polymorphism, found in 10 donors, was the most common SNP. The size of the CD177 bright‐staining neutrophil population was greater in 42C/C donors than in 42G/G donors (66 ± 20% vs. 41 ± 21%, p = 0.004).

CONCLUSIONS:  PRV‐1 and NB1 are alleles of the polymorphic gene CD177. The most common SNP in bp 42 predicted an amino acid change that may have an effect on protein expression.