bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantification of discrete oxide and sulfur layers on sulfur‐passivated InAs by XPS
Authors: Petrovykh D. Y. , Sullivan J. M. , Whitman L. J. 
Published: October 2005

AbstractThe initial quality and stability in air of InAs(001) surfaces passivated by a weakly‐basic solution of thioacetamide (CH3CSNH2) is examined by XPS. The S‐passivated InAs(001) surface can be modeled as a sulfur‐indium‐arsenic ‘layer‐cake’ structure, such that characterization requires quantification of both arsenic oxide and sulfur layers that are at most a few monolayers thick. This thickness range complicates the quantitative analysis because neither standard submonolayer nor thick‐film models are applicable. Therefore, we develop a discrete‐layer model and validate it with angle‐resolved XPS data and electron attenuation length (EAL) calculations. We then apply this model to empirically quantify the arsenic oxide and sulfur coverage on the basis of the corresponding XPS intensity ratios. Copyright © 2005 John Wiley & Sons, Ltd.
Monte Carlo simulation of X‐ray emission using the general‐purpose code PENELOPE
Authors: Llovet X. , Fernández‐Varea J. M. , Sempau J. , Salvat F. 
Published: October 2005

AbstractPENELOPE is a general‐purpose Monte Carlo code system for the simulation of coupled electron and photon transport. It is applicable to all materials and covers the energy range from 50 eV up to 1 GeV. The code implements the most reliable cross sections and relaxation data available for the elements. Cross sections for molecules are generated by adding the atomic cross sections of the constituent atoms. The simulation of electron and positron histories is performed by using a mixed, class II, scheme; hard interactions are simulated individually, whereas the effect of soft interactions is described using multiple‐scattering approximations. The code includes a flexible geometry package for automatic tracking of particles in complex geometries consisting of homogeneous bodies limited by quadric surfaces. In this article, we describe briefly the interaction models and transport algorithms implemented in PENELOPE and present results of simulations of X‐ray generation by electron beams. Copyright © 2005 John Wiley & Sons, Ltd.
Cross sections for electron interactions in condensed matter
Authors: Fernández‐Varea J. M. , Llovet X. , Salvat F. 
Published: October 2005

AbstractThe fundamental components of Monte Carlo algorithms for the simulation of electron transport in matter are the differential and total cross sections for the relevant interaction mechanisms. We present different theoretical models and approximations to compute these cross sections for elastic scattering, inelastic collisions and bremsstrahlung emission of electrons with kinetic energies larger than about 100 eV. We limit our considerations to those models that are broadly applicable and suited for efficient random sampling. The approximations underlying the various models and their range of applicability are discussed. Copyright © 2005 John Wiley & Sons, Ltd.
Monte Carlo strategies for simulations of electron backscattering from surfaces
Authors: Jablonski A. , Powell C. J. , Tanuma S. 
Published: October 2005

AbstractReliable algorithms for simulation of electron trajectories in solids are needed for quantification of Auger‐electron spectroscopy, particularly for the determination of the backscattering factor (BF). The computational schemes for this purpose should be universal, i.e. applicable to any solid for energies down to 50 eV. In addition, the algorithms should ideally require simple input parameters, e.g. the stoichiometry of the solid and the experimental configuration. Previous Monte Carlo simulations have often been based on the continuous slowing down approximation (CSDA), a relatively simple and convenient approach. However, this approach requires information on the electron stopping power for a given solid. General expressions for the stopping power are briefly reviewed and discussed. We report results of BF calculations for Cu M3VV, Ag M5VV, and Au N67VV Auger transitions from Monte Carlo simulations based on the CSDA in which stopping powers from optical data and from Tougaard's two‐parameter universal inelastic‐scattering cross section were employed. The resulting BFs, for primary energies between 500 eV and 10 keV, differed by up to 12% (at an energy of 10 keV). BFs from the Monte Carlo algorithm based on the CSDA were compared with similar results from a more sophisticated code involving simulations of individual elastic‐ and inelastic‐scattering events. Both algorithms yielded equivalent BFs for the same Auger transitions with primary energies exceeding 1000 eV; at lower energies, deviations up to 10% occurred because of an approximation in the evaluation of an integral. Copyright © 2005 John Wiley & Sons, Ltd.
Monte Carlo modeling of electron‐excited X‐ray emission from bulk materials and thin‐film/substrate systems
Authors: Nagatomi T. 
Published: October 2005

AbstractA Monte Carlo (MC) simulation model for the calculation of electron‐excited X‐ray spectra was developed. The model includes characteristic K‐ and L‐lines and continuous X‐ray emission by electron impact, fluorescent X‐ray emission following absorption of continuous and characteristic X rays, L‐line X‐ray emission following K‐shell ionization and Coster‐Kronig transitions. The simulated spectra were directly compared with experimental spectra without any fitting parameters. This comparison revealed that continuous X‐ray and K‐line peak intensities can be well reproduced by the present simulation. The applications of Gryzinski's and Casnati's ionization cross sections to L‐shell ionization resulted in underestimation of the L‐line peak intensity by 10 to ∼30% and overestimation by 20 to ∼40%, respectively. Casnati's equation was found to be applicable to describing L‐shell ionization by MC modeling when the Coster‐Kronig transition was neglected. Copyright © 2005 John Wiley & Sons, Ltd.
Why is it possible to detect doped regions of semiconductors in low voltage SEM: a review and update
Authors: El‐Gomati M. , Zaggout F. , Jayacody H. , Tear S. , Wilson K. 
Published: October 2005

AbstractThere is an urgent need for fast, non‐destructive and quantitative two‐dimensional dopant profiling of modern and future ultra large‐scale semiconductor devices. The low voltage scanning electron microscope (LVSEM) has emerged to satisfy this need, in part, whereby it is possible to detect different secondary electron yield values (brightness in the SEM signal) from the p‐type to the n‐type doped regions as well as different brightness levels from the same dopant type. The mechanism that gives rise to such a secondary electron (SE) contrast effect is not fully understood, however. A review of the different models that have been proposed to explain this SE contrast is given. We report on new experiments that support the proposal that this contrast is due to the establishment of metal‐to‐semiconductor surface contacts. Further experiments showing the effect of instrument parameters including the electron dose, the scan speeds and the electron beam energy on the SE contrast are also reported. Preliminary results on the dependence of the SE contrast on the existence of a surface structure featuring metal‐oxide semiconductor (MOS) are also reported. Copyright © 2005 John Wiley & Sons, Ltd.
A flexible and efficient approach to E‐beam proximity effect correction—PYRAMID
Authors: Lee Soo‐Young 
Published: October 2005

AbstractElectron scattering in the resist causes blurring of the written circuit features in electron‐beam (E‐beam) lithography, which is referred to as the proximity effect. As the feature size in a circuit pattern is continuously reduced in an effort to increase circuit density, the proximity effect has become too prominent to be ignored any more. Without a proper correction of the proximity effect, the pattern density and feature shapes that can be fabricated would be significantly limited especially for nanoscale circuit patterns. A hierarchical approach, named PYRAMID, was proposed in order to develop a flexible and efficient method for proximity effect correction. It distinguishes itself from other methods in that it takes a two‐level approach to exposure estimation and modification of shape and/or dose of circuit features. The hierarchical approach of PYRAMID, which exploits the shape of a typical point spread function (PSF) of the E‐beam lithographic process, attempts to reduce the computational requirement without degrading correction accuracy substantially. Through experiments and simulation, it has been demonstrated that PYRAMID has a potential to be a practical E‐beam proximity effect correction method. Currently, PYRAMID is being extended for grayscale lithography and nonrectangular features. Copyright © 2005 John Wiley & Sons, Ltd.
Modeling of imaging processes in the low‐vacuum SEM
Authors: Thiel Bradley L. 
Published: October 2005

AbstractThe presence of a gas in the specimen chamber of low‐vacuum scanning electron microscopes (SEMs) gives rise to a number of interactions that are not found in their high‐vacuum counterparts. Many of these interactions are integral to the specimen charge neutralizing capabilities of these instruments. However, these interactions, and the electronic charge state of the specimen, give rise to a number of processes that influence, and sometimes even dominate, secondary electron contrast. As many of the processes are stochastic in nature, and depend on discrete interactions between electrons, gaseous ions, neutral molecules, and the specimen surface, modeling can offer important insights for contrast interpretation. This paper discusses these interactions and the mechanisms through which contrast is influenced. Copyright © 2005 John Wiley & Sons, Ltd.
Monte Carlo simulation of Nb Kα secondary fluorescence in EPMA: comparison of PENELOPE simulations with experimental results
Authors: Fournelle John H. , Kim Sungtae , Perepezko John H. 
Published: October 2005

AbstractSecondary fluorescence across phase boundaries is a difficult problem encountered in several electron probe microanalysis (EPMA) situations: diffusion couples; small phases enclosed in a larger phases; eutectic intergrowths; and thin films. In some cases, it is possible to construct nondiffused couples and to measure the amount of secondary fluorescence across the phase boundary, but in most cases this is difficult, time consuming, expensive, or impossible. It is thus desirable to model the secondary fluorescence by Monte Carlo methods. Here we compare the results of experimentally measured secondary fluorescence of Nb K α with results from the PENELOPE Monte Carlo program, and find that there is close correspondence. Copyright © 2005 John Wiley & Sons, Ltd.
EBSD geometry in the SEM: simulation and representation
Authors: Deal Andrew , Tao Xiaodong , Eades Alwyn 
Published: October 2005

AbstractTo obtain a sufficient electron backscatter diffraction (EBSD) signal in the scanning electron microscope (SEM), the sample is highly tilted. This significantly increases both the backscatter yield and the percentage of electrons that are scattered in a forward direction, making them available for detection by the phosphor screen of the EBSD camera. Unlike a conventional Everhart–Thornley detector in SE mode, which collects electrons of multiple trajectories via an applied voltage, the exact position of the phosphor screen with respect to the sample determines what solid angle of the forward scattered electrons is detected. Poor positioning of the camera or an unfavorable working distance may result in patterns that are less than ideal, increasing the difficulty of automated indexing or phase identification. Accordingly, we have used a single‐scattering Monte Carlo model to simulate electron transport through tilted samples. Results of the simulations include tracking the spatial and energy distributions of the electrons during three phases of the process: within the interaction volume, on exiting the sample surface, and when reaching the phosphor screen. Subsequent analysis fosters a better understanding of the geometric requirements for EBSD. Furthermore, our graphical representation of the Monte Carlo results is, we feel, a significant improvement over ‘connect‐the‐dots’ figures typical of the literature, providing greater insight into the nature of the backscatter yield from tilted samples. Copyright © 2005 John Wiley & Sons, Ltd.
Gelatinisation Properties of Cassava Starch in the Presence of Salts, Acids and Oxidising Agents
Authors: Jyothi Alummoottil N. , Sasikiran Korappatti , Sajeev Moothandasseri S. , Revamma R. , Moorthy Subramoney N. 
Published: October 2005

AbstractThe effect of various cations, anions, acids and oxidising agents on the gelatinisation properties of cassava starch was studied and wide variation was observed in the pasting and swelling properties. Sodium chloride and sodium thiosulphate slightly lowered the peak viscosity of cassava starch with increase in concentration, whereas with sodium sulphite, calcium chloride and sodium hypochlorite, a more significant decrease in the viscosity and breakdown was observed. Ferrous sulphate, alum, aluminium chloride and acids enhanced the peak viscosity at lower concentrations followed by a decrease at 1% and above. Sodium metabisulphite elevated the viscosity at 0.05 and 0.1%, while sodium hypochlorite lowered the viscosity and breakdown. DSC studies showed that aluminium chloride, sodium sulphite, and sodium thiosulphate brought about an increase in Tonset, Tend and ΔH values at higher concentrations. A decrease in swelling volume was observed from 0.05 to 1% concentration of sodium chloride and above that there was a gradual increase. With sodium sulphite, a significant increase in swelling volume was observed at 2.5 and 5% levels. With 0.05 and 0.1% aluminium chloride and sodium metabisulphite an increase in swelling volume was noticed, but at higher concentrations there was a drastic fall. Sodium chloride, sodium sulphite, sodium thiosulphate and calcium chloride brought about decrease in starch paste clarity with increase in salt concentration, whereas ferrous sulphate, aluminium chloride, sodium hypochlorite, hydrochloric acid and acetic acid improved the starch paste clarity.
Analogical Modeling and morphological change: the case of the adjectival negative prefix in English
Authors: CHAPMAN DON , SKOUSEN ROYAL 
Published: October 2005

This article examines the usefulness of Skousen's Analogical Modeling (AM) for explaining morphological change. In contrast to previous accounts of analogy, AM constitutes a general unified model of language that accounts for both sporadic and systematic changes. AM also provides explicit constraints on analogy that allow explanation of how morphological changes begin, which forms most likely serve as patterns for analogy, and which forms are most likely to change.AM is then tested on the case of the adjectival negative prefix in English (in-, un-, dis-, etc.), using the Middle and Early Modern English portions of the Helsinki corpus as a basis for prediction. AM was given the task of using forms containing negative prefixes for one time period to predict the prefixes that adjectives would take in the subsequent time period. For each of the roughly seventy-year periods in the corpus, AM was able to predict valid prefixes about 90 percent of the time.
Role of interleukin‐6 in hypoxic regulation of intestinal iron absorption
Authors: Raja Kishor B. , O. Latunde‐Dada Gladys , Peters Timothy J. , McKie Andrew T. , Simpson Robert J. 
Published: October 2005

SummaryThe regulation of intestinal iron absorption is not fully understood. Hepcidin, a liver‐produced peptide, has recently been identified as a negative regulator of iron absorption in various conditions associated with altered iron metabolism (e.g. inflammation, anaemia, hypoxia). It is not clear whether these perturbants share a common signalling pathway. In this study, the importance of the cytokine interleukin‐6 (IL‐6) was investigated in the hypoxic mouse model. Hypoxia was associated with increased levels of circulating IL‐6, decreased liver hepcidin mRNA and increased iron absorption (especially MT). A significant positive correlation existed between the total iron uptake and IL‐6 levels in circulation. IL‐6 per se, though inducing hepcidin mRNA, failed to affect basal iron absorption. The adaptive response to absorption following the hypoxic exposure was, however, more prominent if mice had been treated concurrently with IL‐6. This enhancement in absorption occurred even though hepcidin mRNA was not significantly changed. Similar prominent responses were seen with both human and mouse IL‐6. Anti‐IL‐6 antiserum normalised iron absorption in mice exposed to hypoxia, because of a reduction in the MT. These data indicate that IL‐6 can influence iron absorption (especially MT) during the hypoxic exposure, but via a mechanism independent of hepcidin.
Randomised comparison of two B‐cell purging protocols for patients with B‐cell non‐Hodgkin lymphoma: in vivo purging with rituximab versus ex vivo purging with CliniMACS CD34+ cell enrichment device
Authors: van Heeckeren Willem J. , Vollweiler Jennifer , Fu Pingfu , Cooper Brenda W. , Meyerson Howard , Lazarus Hillard M. , Simic Alexandra , Laughlin Mary J. , Gerson Stanton L. , Koç Omer N. 
Published: October 2005

SummaryWe investigated the feasibility, safety and efficacy of two B‐cell purging methods in patients with CD20+ non‐Hodgkin lymphoma (NHL) receiving autologous stsem cell transplantation. Myeloid and immune recoveries between the methods were compared. Twenty‐seven patients were randomised to either in vivo purging with rituximab or ex vivo purging by CD34+ cell selection. Both purging methods were efficient at eliminating B‐cells in infusates. When compared with in vivo purging, ex vivo purging was associated with CD34+ cell loss and delayed median neutrophil (10 d vs. 11 d) and platelet (12·5 d vs. 17 d) count recoveries. Lymphocyte recovery was similar in both groups, but immunoglobulin recovery was delayed after in vivo purging. Late‐infectious complications were few in both arms. At a median follow‐up of 27 months, 2‐year probabilities of event‐free survival (EFS) rates were 81% for in vivo purging and 76% for ex vivo purging (P = 0·66). When compared with 53 unpurged patients, all 27 purged patients had improved 3‐year probabilities of overall survival (89% vs. 70%, P = 0·014) and a trend for improved EFS (78% vs. 57%, P = 0·075). In conclusion, although both purging methods were feasible and safe, rituximab purging was superior as it did not impair CD34+ cell mobilisation and was associated with faster myeloid recovery. Further studies are needed to determine whether rituximab purging is more effective than the use of unpurged autografts.
Phytoplankton community assembly in a large boreal lake – deterministic pathways or chaotic fluctuations?
Authors: SOININEN JANNE , TALLBERG PETRA , HORPPILA JUKKA 
Published: October 2005

Summary1. The concepts of community assembly and succession are closely related, yet their foci differ slightly. Succession describes the trajectory of species replacements during the temporal development of the community, while assembly also allows that a locality can harbour different communities depending on the events in the near past of community development.2. The aims of this study were (i) to examine the year‐to‐year variation in phytoplankton community assembly among basins of different trophy and disturbance in the large boreal Lake Hiidenvesi and (ii) to assess community persistence and diversity among basins in relation to prevailing environmental factors.3. The results showed that the assembly did not follow similar trajectories each year. According to mean similarity analyses, there was a large degree of variability especially among the groups of samples collected in the same months of different years. Similarity between pairs of consecutive samples was highest in a cold year (1998) in all basins. Community assembly was most unpredictable in the basin of highest productivity, perhaps implying that the number of alternative stable states increased towards higher productivity. Our data also showed a strong unimodal relationship between phytoplankton species richness and grazing by cladoceran zooplankton in the basin of highest trophy.4. This study showed that phytoplankton community assembly exhibited large variability among the years. This implies that different environmental conditions might be the strongest mechanism behind this pattern, given that the degree of community similarity paralleled the year‐to‐year variation in mean temperature. Unravelling the patterns in community assembly has a number of important implications, especially for the monitoring of ecological impacts based only on snapshots of biological assemblages.
Genetic diversity and historical population structure in the New Zealand mayfly Acanthophlebia cruentata
Authors: SMITH PETER J. , MARGARET MCVEAGH S. , COLLIER KEVIN J. 
Published: October 2005

Summary1. Nucleotide sequences of a 280 base pair region of the cytochrome b gene were used to assess genetic diversity and to infer population histories in the New Zealand mayfly Acanthophlebia cruentata.2. A hierarchial examination of populations from 19 streams at different spatial scales in the central and northern North Island of New Zealand found 34 haplotypes. A common haplotype was found in all central region streams and unique haplotypes in northern streams. Several central streams had region specific haplotypes with genetically differentiated populations at the 70–100 km scale.3. Haplotype diversity was high (0.53–0.8) at most sites, but low (0–0.22) in some central sites. amova analyses found significant genetic diversity among regions (69%) and among catchments (58%). Most population pairwise FST tests were significant, with non‐significant pairwise tests among sites in the central region and pairs of sites between neighbouring streams.4. The levels of sequence divergence are interpreted as the result of Pleistocene divergence in multiple refugia, leading to the evolution of regionally unique haplotypes. The low diversity in some central region populations may result from recent colonisation following local extinctions, associated with volcanic events.
Characterization of blond and Star Ruby (red) Jaffa grapefruits using antioxidant and electrophoretic methods
Authors: Gorinstein Shela , Drzewiecki Jerzy , Park Yong‐Seo , Jung Soon‐Teck , Kang Seong‐Gook , Haruenkit Ratiporn , Toledo Fernando , Katrich Elena , Trakhtenberg Simon 
Published: October 2005

SummaryAntioxidant and electrophoretic methods were used to characterize the quality differences between blond and Star Ruby (red) grapefruits. Dietary fibre, minerals and trace elements, total polyphenols, anthocyanins, flavonoids, phenolic and ascorbic acids were also determined. The antioxidant potential of red grapefruit was significantly higher than that of the blond fruit (P < 0.05) and correlated well with the total polyphenols (R2 from 0.8456 to 0.9711). In both the cultivars studied, thirty‐two electrophoretic bands were detected [sodium dodecyl‐polyacrylamide gel eletrophoresis (SDS‐PAGE)]. The main electrophoretic bands occurred between 20 and 43 kDa in both grapefruits with few minor differences between the varieties. Our findings indicate the following (i) red grapefruit is preferable: it has a higher concentration of bioactive compounds and antioxidant potential than the blond; (ii) 1, 1‐diphenyl‐2‐picrylhydrazyl (DPPH) test is a more sensitive method for the determination of antioxidant potential; (iii) there are some minor differences in electrophoretic patterns; (iv) antioxidant and electrophoretic methods are a good combination for characterization of differences of the same citrus fruits.