bluuebunny/crossref_metadata_2025 huggingface dataset:
Variational solution of fractional advection dispersion equations on bounded domains in ℝd
Authors: Ervin Vincent J. , Roop John Paul
Published: July 2006

In this article, we discuss the steady state fractional advection dispersion equation (FADE) on bounded domains in ℝd. Fractional differential and integral operators are defined and analyzed. Appropriate fractional derivative spaces are defined and shown to be equivalent to the fractional dimensional Sobolev spaces. A theoretical framework for the variational solution of the steady state FADE is presented. Existence and uniqueness results are proven, and error estimates obtained for the finite element approximation. © 2006 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 23: 256–281, 2007
Construction of nonstandard finite difference schemes for $1{1\over 2}$ space‐dimension‐coupled PDEs
Authors: Mickens Ronald E. , Jordan P.M.
Published: July 2006

Two coupled PDEs, where one has a diffusion term and the other does not, are defined to be
$1{1\over 2}$
space‐dimension systems. We show how to construct nonstandard finite difference schemes for such systems and demonstrate that they are positivity‐preserving. These methods also allow the calculation of an explicit functional relationships between the time and space step‐sizes. The case of water flowing through fractured bedrock is used to illustrate our procedure. © 2006 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007
Superconvergence of finite volume element method for a nonlinear elliptic problem
Authors: Bi Chunjia
Published: July 2006

In this article, we consider the finite volume element method for the second‐order nonlinear elliptic problem and obtain the H1 and W1,∞ superconvergence estimates between the solution of the finite volume element method and that of the finite element method, which reveal that the finite volume element method is in close relationship with the finite element method. With these superconvergence estimates, we establish the Lp and W1,p (2 < p ≤ ∞) error estimates for the finite volume element method for the second‐order nonlinear elliptic problem. © 2006 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007
A note on adaptive approximation in Sobolev spaces
Authors: Liu Song‐Tao
Published: July 2006

In this article, we consider the adaptive approximation in Sobolev spaces. After establishing some norm equivalences and inequalities in Besov spaces, we are able to prove that the best N terms approximation with wavelet‐like basis in Sobolev spaces exhibits the proper approximation order in terms of N−1. This indicates that the computational load in adaptive approximation is proportional to the approximation accuracy. © 2006 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007
Numerical solution of the one‐dimensional wave equation with an integral condition
Authors: Saadatmandi Abbas , Dehghan Mehdi
Published: July 2006

The hyperbolic partial differential equation with an integral condition arises in many physical phenomena. In this research a numerical technique is developed for the one‐dimensional hyperbolic equation that combine classical and integral boundary conditions. The proposed method is based on shifted Legendre tau technique. Illustrative examples are included to demonstrate the validity and applicability of the presented technique. © 2006 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 23: 282–292, 2007
New kinds of solitons and periodic solutions to the generalized KdV equation
Authors: Wazwaz Abdul‐Majid
Published: July 2006

In this work, the sine‐cosine method, the tanh method, and specific schemes that involve hyperbolic functions are used to study solitons and periodic solutions governed by the generalized KdV equation. New solutions are determined by using the hyperbolic functions schemes. The study introduces new approaches to handle nonlinear PDEs in the solitary wave theory. © 2006 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 23: 247–255, 2007
In vitro evaluation of cellulose acetate hemodialyzer immobilized with heparin
Authors: Kung Fu‐Chen , Chou Wen‐Li , Yang Ming‐Chien
Published: July 2006

In this study, heparin was immobilized onto cellulose acetate hollow fibers to improve the anticoagulation performance during hemodialysis. In vitro evaluation was carried out using mini‐hemodialyzer circulating with fresh porcine whole blood to simulate kidney therapy. The dialysis performance and hemocompatibility were estimated. The results showed that heparinized hemodialyzer could be used through out the whole dialysis time (4 hr) without injecting additional heparin to prevent coagulation in the dialysis system. In addition, the hemocompatibility was evaluated by measuring activated partial thromboplastin time (APTT), prothrombin time (PT), and fibrinogen time (FT). The complete blood count (CBC) including red blood cell (RBC), hemoglobin (Hgb), hematocrit (Hct), white blood cell (WBC), and platelet were determined. The results showed that heparinization could keep the CBC stable during dialysis, whereas unmodified cellulose acetate hemodialyzer would cause a decrease in RBC unless heparin was injected during dialysis. Heparinized hemodialyzer showed longer APTT, PT, and FT than unmodified hemodialyzer. Heparinized hemodialyzer also showed slightly higher clearance than unmodified hemodialyzer. These results indicated that the dialysis performance and hemocompatibility of cellulose acetate hemodialyzer could be improved by the immobilization of heparin. Copyright © 2006 John Wiley & Sons, Ltd.
PIN1 expression contributes to hepatic carcinogenesis
Authors: Pang RW , Lee TK , Man K , Poon RT , Fan S‐T , Kwong Y‐L , Tse E
Published: July 2006

The phospho‐Ser/Thr‐Pro specific prolyl‐isomerase PIN1 is over‐expressed in more than 50% of hepatocellular carcinomas (HCCs). To investigate its potential oncogenicity, we over‐expressed PIN1 in a non‐transformed human liver cell line MIHA. This resulted in up‐regulation of β‐catenin and cyclin D1, leading to anchorage‐independent growth in soft agar and tumorigenicity in nude mice. To further validate the role of PIN1 in hepatocarcinogenesis, PIN was suppressed by RNA interference (siRNA) in the HCC cell line PLC/PRF/5. siRNA‐PIN1 transfection of PLC/PRF/5 cells led to repression of PIN1 expression, resulting in decreased levels of β‐catenin and cyclin D1. siRNA‐PIN1 transfectants showed lower cell proliferation rates, reduced colony formation, and retarded cell cycle progression, with an increase in cells residing in G0/G1. Furthermore, soft agar colony formation was depressed, and tumorigenicity in nude mice was abrogated. These findings implicate PIN1 expression as an important step in hepatic carcinogenesis. Copyright © 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Expression of the TAL1/SCL transcription factor in physiological and pathological vascular processes
Authors: Tang T , Shi Y , Opalenik S R , Brantley‐Sieders D M , Chen J , Davidson J M , Brandt S J
Published: July 2006

The TAL1/SCL transcription factor is essential for haematopoietic commitment and vascular remodelling during embryonic development. To help clarify its role in postnatal vascular processes, we characterized the expression of mouse Tal1 protein by immunocytochemistry in several experimental models of blood vessel formation. In adult mice, Tal1 protein was expressed in rare microvascular endothelial cells and in extravascular cells provisionally identified as endothelial progenitors from their morphology, proximity to vessels and expression of vascular endothelial growth factor receptor‐2. The number of Tal1‐expressing endothelial cells increased significantly but transiently in all the models—hormone‐induced ovulation, wound healing and tumour development. Finally, Tal1 protein was detected in the nuclei of newly formed lymphatic endothelial cells in tumour‐bearing animals. These results show that TAL1 is expressed by vascular endothelial cells and endothelial progenitors at sites of physiological and pathological neovascularization and suggest a role for this transcription factor in adult vasculogenesis. This work also provides the first evidence for TAL1 expression in lymphangiogenesis. Copyright © 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Epididymal cystadenomas and epithelial tumourlets: effects of VHL deficiency on the human epididymis
Authors: Gläsker S , Tran MGB , Shively SB , Ikejiri B , Lonser RR , Maxwell PH , Zhuang Z , Oldfield EH , Vortmeyer AO
Published: July 2006

Although epididymal cystadenomas (ECAs) are among the most frequent VHL disease‐associated tumours, fundamental questions about their pathogenesis have remained unanswered. Classification of ECAs is controversial, and the cell of origin is unknown. It is also unknown whether ECAs—like other VHL disease‐associated tumours—arise as a result of VHL gene inactivation, and whether ECAs exhibit subsequent activation of hypoxia‐inducible factor HIF. Moreover, the morphological spectrum of earliest ECA formation is unknown. In a detailed molecular pathological analysis of a series of epididymides collected from VHL patients at autopsy, we found that ECAs are true neoplasms that arise secondary to inactivation of the wild‐type copy of the VHL gene, followed by early and simultaneous activation of HIF1 and HIF2 associated with up‐regulation of downstream targets, including CAIX and GLUT‐1. The observations also indicate that ECA formation evolves from a variety of microscopic epithelial tumourlets, and that these tumourlets are confined to the efferent ductular system. Although genetic and immunohistochemical analysis of precursor structures consistently revealed VHL gene inactivation and activation of HIF in the precursor lesions, only a small subset appears to progress into frank cystadenoma. Thus, ECA tumorigenesis in VHL disease shares fundamental principles with tumorigenesis in other affected organ systems. Copyright © 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Putting the colours into chromogenic in situ hybridization (CISH)
Authors: Shipley J
Published: July 2006

Recurrent genomic alterations are the hallmarks of particular cancers. Application of molecular cytogenetic technologies to tumour material in order to detect these alterations has become important for molecular diagnostics and research. A dual‐colour chromogenic in situ hybridization (dc‐CISH) method described recently in the Journal of Pathology has the advantage of visualizing two probes simultaneously with the ability to discern morphological features. In addition, the bright field microscopy required is readily accessible to many laboratories. The approach has been validated by comparison of results with standard analyses for HER‐2 amplification status in formalin‐fixed, paraffin‐embedded breast cancers and is applicable to the analysis of other clinically relevant genomic aberrations as well as of use in research investigations. Copyright © 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Redox chemistry of 8‐azaadenine: a pulse radiolysis study
Authors: Pramod G. , Mohan H. , Manoj P. , Manojkumar T. K. , Manoj V. M. , Mittal J. P. , Aravindakumar C. T.
Published: July 2006

Aza derivatives of purines and pyrimidines are important class of compounds, which are known for their cytotoxic, antimicrobial, and mutagenic activities. The redox chemistry of 8‐azaadenine (8AA) has been investigated using pulse radiolysis technique. The oxidation reactions were studied using hydroxyl radical (.OH), oxide radical anion (O.− and sulfate radical anion (SO), and the reduction reactions were studied using hydrated electron (e) and hydrogen radical (H.). In the reaction of .OH, a bimolecular rate constant of 3.8 × 108 dm3 mol−1 s−1 was determined at pH 6.0. The transient spectrum obtained for the reaction of .OH at pH 6 has an absorption maximum around 340 nm and is assigned to the formation of 8AA‐4OH.. The charge population density was calculated theoretically (using Gaussian 98) and it showed that the fourth carbon atom (C(4)) is the most probable site for the attack of .OH. The oxidizing nature of this radical is demonstrated by its reaction with N,N,N′,N′‐tetramethyl‐p‐phenylenediamine (TMPD). The existence of this species is further supported by theoretical calculations where the absorption maximum of this radical is calculated as 338 nm. The yield of 8AA‐4OH. is estimated as around 85%. At pH 10.2, the transient spectrum with maxima at 300 and 350 nm is attributed to the dehydrated 8AA‐4OH., which is an N‐centered radical of the type 8AA‐N(9).. In the reaction of O.− (pH ≈ 14) a transient spectrum with similar features is observed. Therefore this is also assigned to 8AA‐N(9).. A bimolecular rate constant for this reaction is determined as 4.2 × 108 dm3 mol−1 s−1. In the reaction of SO at pH 6, the transient spectrum having λmax at 320 nm is attributed to the formation of a neutral radical of 8AA (8AA‐N(6).), which is formed by the deprotonation of the initially formed radical cation. But at pH 10.2, the spectrum is found to be similar to the one observed in the reaction of O.− and hence it is assigned to the formation of the nitrogen‐centered radical 8AA‐N(9).. In the reaction of e, a second‐order rate constant of 1.8 × 1010 dm3 mol−1 s−1 is determined at pH 6 and the transient absorption spectrum with λmax at 330 nm is assigned to the protonated electron adduct of 8AA (8AA(NH.)). The reducing nature of this intermediate is confirmed by the formation of methyl viologen radical cation (MV.+) from its reaction with MV2+. The transient intermediate in the case of the reaction of H. is proposed as 8AA‐C2(H)N(3). at pH 1. Copyright © 2006 John Wiley & Sons, Ltd.
Mechanical endurance of polymer electrolyte membrane and PEM fuel cell durability
Authors: Huang Xinyu , Solasi Roham , Zou Yue , Feshler Matthew , Reifsnider Kenneth , Condit David , Burlatsky Sergei , Madden Thomas
Published: July 2006

The life of proton exchange membrane fuel cells (PEMFC) is currently limited by the mechanical endurance of polymer electrolyte membranes and membrane electrode assemblies (MEAs). In this paper, the authors report recent experimental and modeling work toward understanding the mechanisms of delayed mechanical failures of polymer electrolyte membranes and MEAs under relevant PEMFC operating conditions. Mechanical breach of membranes/MEAs in the form of pinholes and tears has been frequently observed after long‐term or accelerated testing of PEMFC cells/stacks. Catastrophic failure of cell/stack due to rapid gas crossover shortly follows the mechanical breach. Ex situ mechanical characterizations were performed on MEAs after being subjected to the accelerated chemical aging and relative humidity (RH) cycling tests. The results showed significant reduction of MEA ductility manifested as drastically reduced strain‐to‐failure of the chemically aged and RH‐cycled MEAs. Postmortem analysis revealed the formation and growth of mechanical defects such as cracks and crazing in the membranes and MEAs. A finite element model was used to estimate stress/strain states of an edge‐constrained MEA under rapid RH variations. Damage metrics for accelerated testing and life prediction of PEMFCs are discussed. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2346–2357, 2006
Bronchial hyperresponsiveness, atopy, and bronchoalveolar lavage eosinophils in persistent middle lobe syndrome
Authors: Priftis Kostas N. , Anthracopoulos Michael B. , Mermiri Despina , Papadopoulou Athina , Xepapadaki Paraskevi , Tsakanika Constantina , Nicolaidou Polyxeni
Published: July 2006

Most cases of middle lobe syndrome (MLS) in children are considered to be due to asthma and may recover spontaneously; however, in persistent MLS, repeated episodes of infection often institute a vicious cycle that may lead to persistent symptoms and bronchial hyperresponsiveness (BHR). The present study was undertaken to investigate whether asthma, as an underlying diagnosis, is predictive of a favorable outcome of children with persistent MLS. We evaluated 53 children with MLS who underwent an aggressive management protocol that included fiberoptic bronchoscopy (FOB) and bronchoalveolar lavage (BAL). These patients were compared to two other groups: one consisting of children with current asthma but no evidence of MLS (N = 40) and another of non‐asthmatic controls (N = 42), matched for age and sex. Prevalence of sensitization (≥1 aeroallergen) did not differ between patients with MLS and “non‐asthmatics” but was significantly lower than that of “current asthmatics.” A positive response to methacholine bronchial challenge was observed with increased frequency among children with MLS when compared to “current asthmatic” and non‐asthmatic children. Multivariate logistic regression analysis revealed a positive correlation between an increased number of eosinophils in the BAL fluid (BALF) and a favorable outcome, whereas no correlation was detected between sensitization or BHR and BAL cellular components. In conclusion, children with MLS have an increased prevalence of BHR, even when compared to asthmatics, but exhibit prevalence of atopy similar to that of non‐asthmatics. An increased eosinophilic BALF count is predictive of symptomatic but not radiographic improvement of MLS patients after aggressive anti‐asthma management. Pediatr Pulmonol. © 2006 Wiley‐Liss, Inc.
Isolation, structure elucidation and In Vivo hepatoprotective potential of trans‐tetracos‐15‐enoic acid from Indigofera tinctoria Linn.
Authors: Singh B. , Chandan B. K. , Sharma N. , Bhardwaj V. , Satti N. K. , Gupta V. N. , Gupta B. D. , Suri K. A. , Suri O. P.
Published: July 2006

The bioassay guided fractionation of the dried aerial part of Indigofera tinctoria Linn. led to the identification of an active fraction labelled as indigotin. On further chemical analysis, a compound isolated from indigotin was identified and characterized as trans‐tetracos‐15‐enoic acid (TCA). The chemical structure of this compound was established on the basis of physical properties and spectral data, including NMR. It afforded significant hepatoprotection against carbon tetrachloride and paracetamol induced hepatotoxicity in experimental models. Silymarin, a well known plant based hepatoprotective agent, and N‐acetylcysteine, which has proven efficacy as a replenisher of sulfhydryls, were used for relative efficacy. TCA was found to reverse the altered hepatic parameters in experimental liver damage. In the safety evaluation study the oral LD50 was found to be more than 2000 mg/kg, with no signs of abnormalities or any mortality for the 15 day period of observation after administration of a single dose of drug in mice. The studies revealed significant and concentration dependent hepatoprotective potential of TCA as it reversed the majority of the altered hepatic parameters in experimental liver damage in rats and mice and may be useful in the management of liver disorders. Copyright © 2006 John Wiley & Sons, Ltd.
Quantitative determination of rosuvastatin in human plasma by liquid chromatography with electrospray ionization tandem mass spectrometry
Authors: Xu Dong‐Hang , Ruan Zou‐Rong , Zhou Quan , Yuan Hong , Jiang Bo
Published: July 2006

A simple and sensitive liquid chromatography/tandem mass spectrometry method was developed and validated for determining rosuvastatin in human plasma, a new synthetic hydroxymethylglutaryl‐coenzyme A reductase inhibitor. The analyte and internal standard (IS; cilostazol) were extracted by simple one‐step liquid/liquid extraction with ether. The organic layer was separated and evaporated under a gentle stream of nitrogen at 40°C. The chromatographic separation was performed on an Atlantis C18 column (2.1 mm × 150 mm, 5.0 µm) with a mobile phase consisting of 0.2% formic acid/methanol (30:70, v/v) at a flow rate of 0.20 mL/min. The analyses were carried out by multiple reaction monitoring (MRM) using the precursor‐to‐product combinations of m/z 482 → 258 and m/z 370 → 288. The areas of peaks from the analyte and the IS were used for quantification of rosuvastatin. The method was validated according to the FDA guidelines on bioanalytical method validation. Validation results indicated that the lower limit of quantification (LLOQ) was 0.2 ng/mL and the assay exhibited a linear range of 0.2–50.0 ng/mL and gave a correlation coefficient (r) of 0.9991 or better. Quality control samples (0.4, 8, 25 and 40 ng/mL) in six replicates from three different runs of analysis demonstrated an intra‐assay precision (RSD) 7.97–15.94%, an inter‐assay precision 3.19–15.27%, and an overall accuracy (relative error) of < 3.7%. The method can be applied to pharmacokinetic or bioequivalence studies of rosuvastatin. Copyright © 2006 John Wiley & Sons, Ltd.
Surface‐activated chemical ionization and high‐flow gradient chromatography to reduce matrix effect
Authors: Cristoni Simone , Bernardi Luigi Rossi , Gerthoux Piermario , Mocarelli Paolo , Brambilla Maura , Gonella Elisabetta , Guidugli Federico , Cantu Marco
Published: July 2006

The new atmospheric pressure chemical ionization source, named surface‐activated chemical ionization (SACI), has been used in conjunction with high‐flow gradient chromatography to reduce the matrix effect. This high‐flow gradient chromatography approach avoids the co‐elution of analyte and biological matrix compounds that leads to a reduction in quantitation errors due to matrix effect. However, this approach cannot be employed with the classical electrospray ionization (ESI) source that usually works at low eluent flow (< 300 µL/min). SACI can work at high eluent flow (100–2000 µL/min) and can be employed in conjunction with high‐flow gradient chromatography. The reduction in matrix effect in tacrolimus analysis in protein‐precipitated blood samples, an important immunosuppressive agent for renal transplantation, is presented and discussed. Copyright © 2006 John Wiley & Sons, Ltd.
Simple, rapid solid‐phase extraction procedure for the determination of ultra‐trace levels of pyrethroids in ground and sea water by liquid chromatography/electrospray ionization mass spectroscopy
Authors: Gil‐García M. D. , Barranco‐Martínez D. , Martínez‐Galera M. , Parrilla‐Vázquez P.
Published: July 2006

A method based on liquid chromatography/mass spectroscopy with electrospray ionization in positive mode (LC/ESI‐MS) to determine trace levels of pyrethroids in environmental water samples has been developed. The chromatographic and the MS parameters were optimized to obtain the best sensitivity and selectivity for all pesticides. Solid‐phase extraction (SPE) using C18 cartridges was applied for preconcentration of pesticide trace levels (ng/L) in both ground and sea water samples. The preconcentration step was carried out with 800 mL of water sample modified with 200 mL of MeOH to improve the recovery percentages in the SPE procedure. The SPE‐LC/ESI‐MS methodology was applied to determine pyrethroids in ground and sea water samples spiked at ng/L concentration levels. Recoveries obtained in ground water were satisfactory (between 72 and 110%). However, an enhancement of the signals of all pesticides in the sea water was found due to the negative effect of the salt in the ionization source. To eliminate this effect a simple cleanup step of the SPE cartridge using 200 mL of Milli‐Q water was performed. The cleanup removed the matrix effect completely from the marine samples. Thus, the recovery percentages ranged from 80 to 115%. The method was applied to determine ng/L of pyrethroids in both ground and marine water samples with precision values lower than 10%. Copyright © 2006 John Wiley & Sons, Ltd.
Pyrolysis mass spectrometry for distinguishing potential hoax materials from bioterror agents
Authors: Wilkes Jon G. , Rafii Fatemeh , Sutherland John B. , Rushing Larry G. , Buzatu Dan A.
Published: July 2006

Pyrolysis mass spectrometry (PyMS) was investigated as a rapid tool to distinguish potential bioterror hoax materials from samples containing pathogenic bacteria. A pyrolysis time‐of‐flight (TOF) mass spectrometer equipped with an alternative ionization technique, metastable atom bombardment (MAB), was used to produce sample spectra. These spectra were analyzed by principal component and discriminant analysis for pattern recognition. Materials investigated were two strains of Vibrio parahaemolyticus, one of which produced the tdh toxin, two Salmonella enterica serotypes, a biological mosquito control product containing spores of Bacillus thuringiensis, and several white to off‐white powders (which could be used as hoax materials), such as flour, corn starch, methyl cellulose, and xanthan gum. PyMS distinguished bacterial samples from hoax materials. Furthermore, pattern analysis differentiated Vibrios from Salmonellae, Salmonella enterica Anatum from S. enterica Heidelberg, and the two V. parahaemolyticus strains from each other. The B. thuringiensis mixture was distinguished from other bacteria and powders, suggesting that PyMS with pattern recognition may differentiate samples containing pathogens, including Bacillus spp., from nonbiological agents and that it can be a rapid method for detection of bacteria. MS data acquisition took only 7 min for each sample. Published in 2006 by John Wiley & Sons, Ltd.
Electrospray ionization tandem mass spectral analysis of oxidation products of precursors of sulfur mustards
Authors: Tak Vijay , Kanaujia Pankaj K. , Pardasani Deepak , Gupta Arvinda K. , Palit Meehir , Srivastava R. K. , Dubey Devendra K.
Published: July 2006

Electrospray ionization tandem mass spectral (ESI‐MSn) analysis of thiodiglycol, bis(2‐hydroxyethylthio)alkanes (BHETAs) and their mono‐, di‐, tri‐, and tetraoxygenated compounds was carried out to obtain their characteristic spectra for ESI‐MS analysis. These compounds are important markers of chemical warfare agents, namely sulfur mustards. ESI‐MSn (n ≥ 3) analysis of a compound by collisionally induced dissociation in an ion trap gives rise to mass spectra that are somewhat similar to electron ionization mass spectra. These ESI‐MSn spectra can be used for compound identification. Under ESI‐MS and ESI‐MS/MS the compounds mostly produced [M+NH4]+, [M+H]+ and [M+HH2O]+ ions. Fragmentations of these even‐electron precursors in the ion trap gave rise to characteristic product ions via neutral loss of O2, H2O, C2H4, HCHO, C2H4O, C2H4S, HSC2H4OH and C2H4SO. Fragmentation routes of these compounds are proposed that rationalize the formation of product ions in ESI‐MSn analysis. Copyright © 2006 John Wiley & Sons, Ltd.
Analysis of sterols by high‐performance liquid chromatography/mass spectrometry combined with chemometrics
Authors: Nagy Kornél , Jakab Annamaria , Pollreisz Ferenc , Bongiorno David , Ceraulo Leopoldo , Averna Maurizio R. , Noto Davide , Vékey Károly
Published: July 2006

A newly developed high‐performance liquid chromatography/mass spectrometry (HPLC/MS) method has been successfully used to analyze plasma concentrations of various phytosterols (cholestanol and β‐sitosterol) and cholesterol metabolites (desmosterol and lathosterol). This was based on an unusual solvent combination of water/methanol vs. methanol/acetone/n‐hexane applied on a Purospher Star RP‐18e (125 × 2 mm, 3 µm) column, which proved excellent for the separation, identification and quantification of plasma sterols. Simple solid‐phase extraction preparation of plasma samples was performed, followed by the developed fast and robust HPLC separation. Results on four groups of people were compared, those with low, normal and high plasma cholesterol levels and those with high cholesterol levels on statin therapy, and the results were evaluated using linear discriminant analysis (LDA). Variable selection for LDA was achieved using backward removal selection. Highly discriminatory variables were the ratios of desmosterol to sitosterol and of lathosterol to total plasma cholesterol. The latter ratio was also excellent for distinguishing subjects on statin therapy. The success rate of classification was 100%. The present pilot study shows the potential of HPLC/MS analysis and chemometrics for studying cholesterol‐related disorders and warrants future full‐scale medical study. Copyright © 2006 John Wiley & Sons, Ltd.
Systematic examination of the signal area precision of a single quadrupole enhanced low mass option (ELMO) TSQ™ mass spectrometer
Authors: Fischer Klaus , Höffler Susanne , Meyer Axel
Published: July 2006

To examine the precision of the signal area response of an enhanced low mass option (ELMO) MSQ™ mass spectrometer, operated in the negative electrospray ionization (ESI) mode, extended tests were performed, using flow injection analysis mass spectrometry (FIA‐MS). Analytes were nitrate, nitrite, malonic acid, and D,L‐mandelic acid. Composition and concentration of injected samples, application of an ASRS anion suppressor and of the cone wash unit, methanol addition to the FIA flow medium, and the voltage bias of the hexapole transfer lens were test variables. Individual test cycles comprised up to 90 injections, processed within 20 h. With a few exceptions the signal response tended to decline over time leading to a loss of more than 80% of the initial signal area in extreme cases. A hexapole radio‐frequency (RF) voltage bias of −0.3 V led to an overall low detector response and to high losses of sensitivity over time. Other correlations between the insufficient signal reproducibility and FIA‐MS operating conditions could not be established. The test scheme gave hints how to localize the cause of the mass spectrometer malfunction. The repetition of the test scheme after remedying the detected electronic default demonstrated that relative standard deviations less than 5% can be achieved for a sequence of 30 injections if methanol is added to the FIA flow medium and if a suppressor is used. Based on these findings a recommendation is formulated to supplement current test schemes for instrument performance verification by a detector response precision criterion. Copyright © 2006 John Wiley & Sons, Ltd.
YOU ARE WHAT YOU EAT UP: DEPOSING CHIEFS IN EARLY COLONIAL NATAL, 1847–58
Authors: MCCLENDON THOMAS
Published: July 2006

This article examines three incidents in the history of early colonial Natal in which colonial forces under Secretary for Native Affairs Theophilus Shepstone attacked subject chiefs, deposed them and seized their herds. These incidents, which presaged the later conflict with Langalibalele, constituted in local African terms ‘eating up’, a practice whereby a chief confiscated the property of a subject convicted of conspiring against him through witchcraft. Close examination of these incidents shows how the early colonial state's rule over African subjects was inevitably imbued with African understandings of power and authority.
THE PSYCHOLOGY OF REBELLION: COLONIAL MEDICAL RESPONSES TO DISSENT IN BRITISH EAST AFRICA
Authors: MAHONE SLOAN
Published: July 2006

This article opens with a retelling of colonial accounts of the ‘mania of 1911’, which took place in the Kamba region of Kenya Colony. The story of this ‘psychic epidemic’ and others like it would be recounted over the years as evidence depicting the predisposition of Africans to episodic mass hysteria. This use of medical and psychological language in primarily non-medical contexts serves to highlight the intellectual and political roles psychiatric ideas played in colonial governance. The salience of such ideas was often apparent in the face of increasing social tension, charismatic leadership and a proliferation of East African prophetic movements. This article addresses the attempts by the colonial authorities to understand or characterize, in psychological terms, a progression of African ‘rebellious types’ in society that often took the form of prophets and visionaries, but were diagnosed as epileptic, neurotic or suffering from ‘religious mania’.
METHODS AND SOURCES FOR AFRICAN HISTORY REVISITED Writing African History. Edited by JOHN EDWARD PHILIPS. Rochester: University of Rochester Press, 2005. Pp. xii+531. $75 (ISBN 1-58046-164-6).
Authors: SPEAR THOMAS
Published: July 2006

WRITING African History pays homage to Daniel McCall's pioneering text, Africa in Time Perspective: A Discussion of Historical Reconstruction from Unwritten Sources, published at the dawn of the era of modern African history in 1964. Surprisingly, given subsequent developments in the field, there has been no comparable text since, making this volume especially welcome. But it also bears a heavy burden if it is to become the authoritative text for the next generations of students and scholars. Does it meet this difficult test?
AFRICAN URBAN HISTORY: FRANCOPHONE AND ANGLOPHONE PERSPECTIVES ‘Cité-Etat et statut politique de la ville’, Journal des Africanistes, numero coordonné par ANNEMARIEPEATRIK et GILLESHOLDER. Paris, tome 74, fasc. 1–2, 2004. Pp. 536. €55 (ISBN 2-908948-16-8).
Authors: FOURCHARD LAURENT
Published: July 2006

Ce double numéro du Journal des Africanistes est issu d'un séminaire organisé entre 1999 et 2002 par l'équipe Afrique du laboratoire d'ethnologie et de sociologie comparative de l'Université de Paris 10 Nanterre. II regroupe 18 contributions d'anthropologues et d'historiens français qui interrogent à partir d'études de cas le fonctionnement du pouvoir local ou ‘le statut politique des localités en Afrique’ (p. 11)avec, en point de mire, deux objets principaux: la ville et la cité. Cette dernière fait l'objet d'une discussion théorique dans les deux chapitres introductifs de l'ouvrage. Jean-Jacques Glassner propose effectivement une recension fort utile des variations sémantiques de la notion de Cité-Etat sur différents continents à différentes périodes. Gilles Holder et Anne-Marie Peatrik s'interrogent pour leur part sur la Cité-Etat et la cité dans le contexte africain. Cette dernière associerait trois types d'espace: l'enceinte (matérielle ou symbolique), l'arrière-pays qui nourrit la cité, et ‘l'outre-pays’, néologisme proposé par les auteurs pour désigner des espaces non dépendants de la cité mais avec lesquels celle-ci entretient des liens économiques, politiques ou religieux (p. 14). Cette définition large permet aux auteurs ne pas opposer d'emblée ville et campagne et de pas dissocier a priori la ville de la cité et la cité de la Cité-Etat. Elle inclut donc des échelles d'analyse plus grandes et plus petites. On pourra en revanche s'étonner de l'absence d'une définition liminaire de la ville (proposée ensuite par différents auteurs), d'une bibliographie qui ne tient pas compte du renouvellement conséquent de l'histoire urbaine, notamment dans le monde anglophone, et de quelques cadrages chronologiques hasardeux (l'intérêt des historiens pour les villes d'Afrique a émergé au début des années 1980 et non au cours de la dernière décennie, p. 10).
Beyond the Mission Civilisatrice: The Properties of a Normative Order within an Internationalized Territory
Authors: KNOLL BERNHARD
Published: July 2006

Theorizing about the operation of law in an internationalized territory involves three discrete dimensions, according to which this article is structured. First, liberal legal forms are transmitted without being subject to mediation by a ‘sovereign’. The diffusion of imported norms represents the precise telos of a mission civilisatrice of a postcolonial institution-building mission. Such internationalization projects realize their liberalizing potential through a complex process where they provide legal continuity while importing legal forms that emphasize discontinuity and progress. In the second dimension, the article accounts for the asymmetric co-government setting exhibited in Kosovo in which law is both municipal and international. The syncretic nature of legal sources limits attempts to establish a ‘hierarchy’ of norms in an internationalized territory. Further, the promised advent of a liberal future is challenged by what this article identifies as the third characteristic of such a transitory legal order – the unaccountability of the international administering agent. These three properties of a normative order entail a paradox in which the aspirations of a fiduciary administration operating in the slipstream of liberal internationalism and its ‘civilizing mission’ are qualified by the absence of key criteria of a Rechtsstaat – the democratic creation of laws, the separation of powers, legal certainty, and the judicial control of normative acts.
Comparative Study of Nanoscale Surface Structures of Calcite Microcrystals Using FE-SEM, AFM, and TEM
Authors: Chien Yung-Ching , Mucci Alfonso , Paquette Jeanne , Sears S. Kelly , Vali Hojatollah
Published: July 2006

The bulk morphology and surface features that developed upon precipitation on micrometer-size calcite powders and millimeter-size cleavage fragments were imaged by three different microscopic techniques: field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) of Pt-C replicas, and atomic force microscopy (AFM). Each technique can resolve some nanoscale surface features, but they offer different ranges of magnification and dimensional resolutions. Because sample preparation and imaging is not constrained by crystal orientation, FE-SEM and TEM of Pt-C replicas are best suited to image the overall morphology of microcrystals. However, owing to the decoration effect of Pt-C on the crystal faces, TEM of Pt-C replicas is superior at resolving nanoscale surface structures, including the development of new faces and the different microtopography among nonequivalent faces in microcrystals, which cannot be revealed by FE-SEM. In conjunction with SEM, Pt-C replica provides the evidence that crystals grow in diverse and face-specific modes. The TEM imaging of Pt-C replicas has nanoscale resolution comparable to AFM. AFM yielded quantitative information (e.g., crystallographic orientation and height of steps) of microtopographic features. In contrast to Pt-C replicas and SEM providing three-dimensional images of the crystals, AFM can only image one individual cleavage or flat surface at a time.
Low-Cost Nanomanipulator forIn SituExperiments in a SEM
Authors: Nakabayashi Denise , Silva Paulo C. , González Juan C. , Rodrigues Varlei , Ugarte Daniel
Published: July 2006

Here, we describe the development of an inexpensive and versatile manipulation system forin situexperiments in a field emission scanning electron microscope based on a parallel-guiding plate-spring mechanism and low cost materials. The system has been tested for a wide range of applications, such as collecting, moving, and positioning particles, fabricating atomic force microscopy tips based on carbon nanotubes, and characterizing individual nanobjects. The nanomanipulation results demonstrate that there are many opportunities for the use of physical manipulation in the bottom-up approach to fabrication of nanodevices.
Sample Preparation for Precise and Quantitative Electron Holographic
Analysis of Semiconductor Devices
Authors: Han Myung-Geun , Li Jing , Xie Qianghua , Fejes Peter , Conner James , Taylor Bill , McCartney Martha R.
Published: July 2006

Wedge polishing was used to prepare one-dimensional Si n-p junction
and Si p-channel metal-oxide-silicon field effect transistor (pMOSFET)
samples for precise and quantitative electrostatic potential analysis
using off-axis electron holography. To avoid artifacts associated with ion
milling, cloth polishing with 0.02-μm colloidal silica suspension was
used for final thinning. Uniform thickness and no significant charging
were observed by electron holography analysis for samples prepared
entirely by this method. The effect of sample thickness was investigated
and the minimum thickness for reliable results was found to be ∼160
nm. Below this thickness, measured phase changes were smaller than
expected. For the pMOSFET sample, quantitative analysis of two-dimensional
electrostatic potential distribution showed that the metallurgical gate
length (separation between two extension junctions) was ∼54 nm,
whereas the actual gate length was measured to be ∼70 nm by
conventional transmission electron microscopy. Thus, source and drain
junction encroachment under the gate was 16 nm.
Quantitative Strain Mapping Applied to Aberration-Corrected HAADF
Images
Authors: Sanchez Ana M. , Galindo Pedro L. , Kret Slawomir , Falke Meiken , Beanland Richard , Goodhew Peter J.
Published: July 2006

A systematic distortion in high-angle annular dark-field scanning
transmission electron microscope (HAADF-STEM) images, which may be caused
by residual electrical interference, has been evaluated. Strain mapping,
using the geometric phase methodology, has been applied to images acquired
in an aberration-corrected STEM. This allows this distortion to be removed
and so quantitative analysis of HAADF-STEM images was enabled. The
distortion is quantified by applying this technique to structurally
perfect and strain-free material. As an example, the correction is used to
analyse an InAs/GaAs dot-in-quantum well heterostructure grown by
molecular beam epitaxy. The result is a quantitative measure of internal
strain on an atomic scale. The measured internal strain field of the
heterostructure can be interpreted as being due to variations of indium
concentration in the quantum dot.
Quantitative Analysis of Microstructures by Secondary Ion Mass
Spectrometry
Authors: Phinney Douglas
Published: July 2006

The focus of this review is on trace-element quantitation of
microstructures in solids. This review is aimed at the nonspecialist who
wants to know how secondary ion mass spectrometry (SIMS) quantitation is
achieved. Despite 35 years of SIMS research and applications, SIMS
quantitation remains a fundamentally empirical enterprise and is based on
standards. The most used standards are “bulk
standards”—solids with a homogeneous distribution of a trace
element—and ion-implanted solids. The SIMS systematics of bulk
standards and ion-implanted solids are reviewed.
Quantitative Thin-Film X-ray Microanalysis by STEM/HAADF:
Statistical Analysis for Precision and Accuracy Determination
Authors: Armigliato Aldo , Balboni Roberto , Rosa Rodolfo
Published: July 2006

Silicon-germanium thin films have been analyzed by EDS microanalysis
in a field emission gun scanning transmission electron microscope
(FEG-STEM) equipped with a high angular dark-field detector
(STEM/HAADF). Several spectra have been acquired in the same
homogeneous area of the cross-sectioned sample by drift-corrected linescan
acquisitions. The Ge concentrations and the local film thickness have been
obtained by using a previously described Monte Carlo based “two tilt
angles” method. Although the concentrations are in excellent
agreement with the known values, the resulting confidence intervals are
not as good as expected from the precision in beam positioning and tilt
angle position and readout offered by our state-of-the-art microscope. The
Gaussian shape of the SiKα and GeKα X-ray intensities allows one
to use the parametric bootstrap method of statistics, whereby it becomes
possible to perform the same quantitative analysis in sample regions of
different compositions and thicknesses, but by doing only one measurement
at the two angles.
Surface Characterization of a Decarburized and Nitrided Steel
Authors: Calliari Irene , Dabalà Manuele , Zanesco Marzia , Bernardo Enrico , Olmi Filippo , Vagelli Gloria
Published: July 2006

This article describes the effects of surface controlled
decarburization on the structure of a nitrided steel. Samples of quenched
and tempered 40CrMo4 steel were decarburized by air heat treatment
(800–900°C) at different depths and submitted to gaseous
nitriding. The microstructure of surface layers after decarburization and
nitriding were investigated by optical (OM) and scanning electron
microscopy (SEM). The nitrogen and carbon profiles in the diffusion layers
were determined by a scanning electron microscope equipped with a
wavelength dispersive spectrometer (EPMA-WDS). The effect of nitriding was
determined by microhardness measurements. The increasing of time and
temperature of decarburization slightly affect the surface hardness
values, while case hardness depths decrease. In all the specimens, the
nitriding depth, as determined by the WDS nitrogen profile, is larger than
the one determined by the hardness profile.
Exploring Hydrothermally Grown Potassium Titanate Fibers by STEM-in-SEM/EDX and XRD
Authors: Habicht Wilhelm , Boukis Nikolaos , Franz Günter , Walter Olaf , Dinjus Eckhard
Published: July 2006

During lab-scale experiments on the reforming of methanol by means of water at supercritical conditions (T> 374°C,p> 22.1 MPa), a tubular reactor with a titanium liner was exposed to an aqueous solvent containing methanol (5 wt%) and KHCO3(0.3 wt%). At the end of the run, a fibrous precipitate was found at two positions in the reactor. The material was studied in a field emission scanning electron microscope equipped with an energy dispersive X-ray analysis unit (FESEM/EDX). A thin-film support technique using carbon-filmed TEM grids was applied to perform scanning transmission-type imaging (STEM-in-SEM operation) and transmission current measurements. The analysis of the hydrothermally grown fibers resulted in a potassium titanate species composed of approximately K2TiO3, which has been confirmed by X-ray diffraction (XRD).
Synthesis and Characterization of Doped and Undoped ZnO
Nanostructures
Authors: McBean Katie E. , Phillips Matthew R. , Goldys Ewa M.
Published: July 2006

Zinc oxide (ZnO) nanoparticles have been produced using precipitation
methods from ethanolic solution. Rare-earth metal doping was performed,
and the effect of lithium codoping on the luminescence properties of the
rare-earth doped products was assessed. The resulting particles were
characterized using cathodoluminescence and scanning electron microscopy.
It was found that lithium significantly enhanced the cathodoluminescence
signal from the rare-earth ions, which has been attributed to the
increased integration of the rare-earth ions into the ZnO structure. The
nanophase ZnO products were also annealed in argon, hydrogen, and oxygen,
with hydrogen being the most successful for removing the broad defect
emission present in as-grown samples and enhancing the ZnO near band edge
emission.
The Low Energy X-ray Spectrometry Technique as Applied to
Semiconductors
Authors: Staub Pierre-François
Published: July 2006

We describe the recent introduction of low energy X-ray emission
spectrometry as a metrology technique to control the fabrication process
in the integrated circuit industry. The benefits of this particular
analytical method and the wide field of potential applications are
addressed.
Practical Aspects of Carbon Content Determination in Carburized
Steels by EPMA
Authors: Robaut Florence , Crisci Alexandre , Durand-Charre Madeleine , Jouanne Danielle
Published: July 2006

The carbon contents in carburized steels were investigated by electron
probe microanalysis (EPMA) for a range of carbon levels in the solid
solution less than 1 wt%. This article describes the difficulties
encountered with the classic analytical procedure using the k
ratio of X-ray intensities and the φ(ρz) model. Here, a
suitable calibration curve method is presented with emphasis on the
metallographic study of standard specimens and on the carbon
decontamination of samples.
Letter to the Editor: Accurate Element Identification is the Core
Requirement for a Microanalysis System
Authors: Burgess Simon
Published: July 2006

We at Oxford Instruments were interested to read the article published
in Microscopy and Microanalysis by Newbury (2005). Although our
own views differ from those of Dr. Newbury in some respects, we do agree
that this is an important matter. If this article generates an interest in
the ability of a system and a user to accurately identify elements in a
spectrum and encourages people to assess the quality of the qualitative
analysis provided by a microanalysis system, then we believe this article
has served a very useful purpose. After all, accurate element
identification is the core requirement for a microanalysis system.