bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of rupatadine in pharmaceutical formulations by a validated stability‐indicating MEKC method
Authors: Nogueira Daniele Rubert , da Silva Sangoi Maximiliano , da Silva Lucélia Magalhães , Todeschini Vítor , Dalmora Sérgio Luiz
Published: August 2008

A stability‐indicating MEKC was developed and validated for the analysis of rupatadine in tablet dosage forms, using nimesulide as internal standard. The MEKC method was performed on a fused‐silica capillary (50 μm id; effective length, 40 cm). The BGE consisted of 15 mM borate buffer and 25 mM anionic detergent SDS solution at pH 10. The capillary temperature was maintained at 35°C and the applied voltage was 25 kV. The injection was performed using the hydrodynamic mode at 50 mbar for 5 s, with detection by photodiode array detector set at 205 nm. The method was linear in the range of 0.5–150 μg/mL (r2= 0.9996). The specificity and stability‐indicating capability of the method were proven through degradation studies inclusive by MS, and showing also that there was no interference of the excipients and no increase of the cytotoxicity. The accuracy was 99.98% with bias lower than 1.06%. The LOD and LOQ were 0.1 and 0.5 μg/mL, respectively. The proposed method was successfully applied for the quantitative analysis of rupatadine in pharmaceutical formulations, and the results were compared to a validated RP‐LC method, showing non‐significant difference (p>0.05).
Analytical and semi‐preparative enantioseparation of organic phosphonates on a new immobilized amylose based chiral stationary phase
Authors: Zhang Yuping , Song Baoan , Bhadury Pinaki S. , Hu Deyu , Yang Song , Shi Xia , Liu Dongmei , Jin Linhong
Published: August 2008

Two chiral stationary phases derived from derivatized amylose (Chiralpak AD‐H and Chiralpak IA) have been used to separate the enantiomers of new diethyl benzamidoarylmethylphosphonates. The data obtained indicate that all the studied compounds could be easily baseline resolved on both columns. Owing to the different techniques involved in their preparation, the two stationary phases differ in their abilities to effect enantiomeric separation. The semi‐preparative separation of all compounds was executed successfully inn‐hexane/EtOH on the new immobilized Chiralpak IA column. The analytical assessment of the enantiomeric excess values of all collected fractions was higher than 97%. The stereochemical configuration for the F1 fraction of a diethyl benzamidoarylmethylphosphonate was determined by X‐ray diffraction structure analysis.
Recent progress of online sample preconcentration techniques in microchip electrophoresis
Authors: Sueyoshi Kenji , Kitagawa Fumihiko , Otsuka Koji
Published: August 2008

Microchip electrophoresis (MCE) has been advanced remarkably by the applications of several separation modes and the integration with several chemical operations on a single planer substrate. MCE shows superior analytical performance, e.g., high‐speed analysis, high resolution, low consumption of reagents, and so on, whereas low‐concentration sensitivity is still one of the major problems. To overcome this drawback, various online sample preconcentration techniques have been developed in MCE over the past 15 years, which have successfully enhanced the detection sensitivity in MCE. This review highlights recent developments in online sample preconcentration in MCE categorized on the basis of “dynamic” and “static” methods. The dynamic techniques including field amplified stacking, ITP, sweeping, and focusing have been easily applied to MCE, which provide effective enrichments of various analytes. The static techniques such as SPE and filtration have also been combined with MCE. In the static techniques, extremely high preconcentration efficiency can be obtained, compared to the dynamic methods. This review provides comprehensive tables listing the applications and sensitivity enhancement factors of these preconcentration techniques employed in MCE.
Determination of four aromatic amines in water samples using dispersive liquid–liquid microextraction combined with HPLC
Authors: Wang Xuedong , Fu Lingyan , Wei Guohui , Hu Jia , Zhao Xinna , Liu Xiujuan , Li Yanyan
Published: August 2008

A new method for the determination of four aromatic amines in water samples was developed by using dispersive liquid–liquid microextraction (DLLME) technique combined with HPLC‐variable wavelength detection (HPLC‐VWD). In this extraction method, 0.50 mL methanol (as dispersive solvent) containing 25.0 μL tetrachloroethane (as extraction solvent) was rapidly injected by a syringe into 5.00 mL water sample. Accordingly, a cloudy solution was formed. After centrifugation for 2 min at 4000 rpm, the fine droplets of the tetrachloroethane containing the analytes were sedimented in the bottom of the conical test tube (7 ± 0.2 μL). Then, 5.0 μL of the settled phase was determined by HPLC‐VWD. Parameters such as the kind and volume of extraction solvent and dispersive solvent, extraction time, and salt concentration were optimized. Under the optimum conditions, the enrichment factors ranged from 41.3 to 94.5. Linearity was observed in the range of 5–5000 ng/mL. The LODs based on S/N of 3 ranged from 0.8 to 1.8 ng/mL. The RSDs (for 400 ng/mL of p‐toluidine and o‐chloroaniline, 100 ng/mL of p‐chloroaniline and p‐bromoaniline) varied from 4.1 to 5.3% (n = 6). The water samples collected from rivers and lakes were successfully analyzed by the proposed method and the relative recoveries were in the range of 85.4–111.7% and 90.2–101.3%, respectively.
Comparison of solid‐phase sorbents for the determination of fluoroquinolone antibiotics in wastewater
Authors: Zorita Saioa , Larsson Lennart , Mathiasson Lennart
Published: August 2008

Three different SPE sorbents (weak cation exchange, mixed cation exchange, and hydrophobic–lipophilic balance polymers) were compared in terms of recovery, precision, and the effect of matrix components on analyte response for the determination of fluoroquinolones antibiotics. The influence of ethylenediaminetetraacetic acid disodium salt (Na2‐EDTA) was as well tested. Two of the sorbents, hydrophilic–lipophilic balance (HLB) and weak cation exchange (WCX), turned out to be suitable for ultratrace analysis. HLB sorbent showed higher capacity for analyte trapping and better precision while weak cation exchange sorbent had a superior performance in terms of selectivity. In complex samples, the higher capacity of HLB was outweighed by the higher selectivity of WCX when considering the LODs of the methods.
Neutral octadecyl monolith for reversed phase capillary electrochromatography of a wide range of solutes
Authors: Karenga Samuel , El Rassi Ziad
Published: August 2008

A neutral octadecyl monolithic (ODM) column for RP capillary electrochromatography (RP‐CEC) has been developed. The ODM column was prepared by the in situ polymerization of octadecyl acrylate (ODA) as the monomer and trimethylolpropanetrimethacrylate (TRIM) as the crosslinker, in a ternary porogenic solvent containing cyclohexanol, ethylene glycol, and water. The ODM column exhibited cathodal EOF over a wide range of pH and ACN concentration in the mobile phase despite the fact that it was devoid of any fixed charges. It is believed that the EOF is due to the adsorption of ions from the mobile phase onto the surface of the monolith thus imparting to the neutral ODM column the zeta potential necessary to support the EOF required for mass transport across the monolithic column. Furthermore, the adsorption of mobile phase ions to the neutral monolith modulated solute retention and affected the separation selectivity. The wide applications of the neutral ODM column were demonstrated by its ability to separate a wide range of small and large solutes, both neutral and charged. While the separation of the neutral solutes was based on RP retention mechanism, the charged solutes were separated on the basis of their electrophoretic mobility and hydrophobic interaction with the C18 ligands of the stationary phase. As a typical result, the neutral monolithic column was able to separate peptides quite rapidly with a separation efficiency of nearly 200 000 plates/m, and this efficiency was exploited in tryptic peptide mapping of standard proteins, e. g., lysozyme and cytochrome C, by isocratic elution.
Determination of enrofloxacin and ciprofloxacin in milk using molecularly imprinted solid‐phase extraction
Authors: Yan Hongyuan , Tian Minglei , Row Kyung Ho
Published: August 2008

A molecularly imprinted solid‐phase extraction procedure was developed for the simultaneous identification of enrofloxacin and its active metabolite, ciprofloxacin, in milk samples. Water‐compatible molecularly imprinted polymers synthesized in a water–methanol system show a high degree of cross‐reactivity for enrofloxacin and ciprofloxacin in aqueous environments. The imprinted particles were applied as selective sorbents in a solid‐phase extraction process focusing upon complex milk matrices, which allowed the matrix compounds present in milk samples to be removed effectively. The extracts were sufficiently clean for further chromatographic analysis, and no interference originating from the biological matrix was observed. The mean recoveries of enrofloxacin and ciprofloxacin from milk sample were 82.6–93.5% and 81.2–94.8%, respectively, with the RSD less than 7.5%. This method is simple and sensitive, and is therefore an alternative tool to the existing HPLC methods for analyzing residual enrofloxacin and ciprofloxacin in biological samples.
Development and validation of a ultra performance LC‐ESI/MS method for analysis of metabolic phenotypes of healthy men in day and night urine samples
Authors: Wang Xijun , Lv Haitao , Zhang Guangmei , Sun Wenjun , Zhou Dixin , Jiao Guozheng , Yu Yang
Published: August 2008

Ultra‐performance LC coupled to quadrupole TOF/MS (UPLC‐QTOF/MS) in positive and negative ESI was developed and validated to analyze metabolite profiles for urine from healthy men during the day and at night. Data analysis using principal components analysis (PCA) revealed differences between metabolic phenotypes of urine in healthy men during the day and at night. Positive ions with mass‐to‐charge ratio (m/z) 310.24 (5.35 min), 286.24 (4.74 min) and 310.24 (5.63 min) were elevated in the urine from healthy men at night compared to that during the day. Negative ions elevated in day urine samples of healthy men included m/z 167.02 (0.66 min), 263.12 (2.55 min) and 191.03 (0.73 min), whilst ions m/z 212.01 (4.77 min) were at a lower concentration in urine of healthy men during the day compared to that at night. The ions m/z 212.01 (4.77 min), 191.03 (0.73 min) and 310.24 (5.35 min) preliminarily correspond to indoxyl sulfate, citric acid and N‐acetylneuraminic acid, providing further support for an involvement of phenotypic difference in urine of healthy men in day and night samples, which may be associated with notably different activities of gut microbiota, velocity of tricarboxylic acid cycle and activity of sialic acid biosynthesis in healthy men as regulated by circadian rhythm of the mammalian bioclock.
Assessing and reporting the quality of commercial weather forecasts
Authors: Mailier Pascal J. , Jolliffe Ian T. , Stephenson David B.
Published: August 2008

In 2005 the Royal Meteorological Society commissioned a study to examine current issues regarding the quality (fitness for purpose) of commercial weather forecasts in the United Kingdom. UK commercial weather forecast providers and users were consulted by means of on‐line questionnaires, interviews, visits and an open workshop discussion. Results from this consultation uncovered significant deficiencies in the methodologies and in the communication of forecast quality assessments, a lack of open dialogue and transparency in the industry, and that some users may be indifferent to forecast quality. Descriptive or worded forecasts cannot be assessed objectively. However, suitable quality assessment methods are available for nearly all types of quantitative forecasts identified in the consultation. The crucial importance of choosing proper quality assessment metrics, the impact of their statistical properties on results and the need to estimate the statistical significance of quality assessment results were exemplified by means of four case studies, one of which is presented in this paper. The findings from this study have led to a set of practical recommendations aiming to establish the discipline and rigour that are necessary for achieving best practice in the quality assessment of weather forecasts. Specific recommendations were also made to the Royal Meteorological Society to set up a special commission that would promote a sense of community within the industry, and to run an accreditation scheme that would encourage best practice on a voluntary basis. Copyright © 2008 Royal Meteorological Society
Spatial and temporal characteristics of aerosol optical depth over East Asia and their association with wind fields
Authors: Bao Zhenhao , Zhu Chize , Hulugalla Ranatunge , Gu Junqiang , Di Guoqing
Published: August 2008

Rotated principal component analysis (PC) was performed on monthly Aerosol Optical Depth (AOD) from Moderate Resolution Imaging Spectroradiometer (MODIS) data over East Asia for the period of March 2000–January 2006. The first PC mode is a south–north dipole with a strong positive loading between 30–35°N and 130–150°E over middle latitude East Asia and a weaker negative loading in southern parts over East Asia. The first PC mode explains 32.44% of the total variance. By analysing time series of the PC1‐3, results show the PC‐1 and PC‐3 modes are important and both have distinct changes from the period 2000–2003 to 2004–2006; the former pattern (in middle latitudes over East Asia) is characterized in a decreasing linear trend and the latter (in eastern China) is in an increasing linear trend in the full 71 month evolution. Furthermore, based on the wavelet power spectrum analysis, it is found that the distinct changes of the monthly AOD in middle latitudes over East Asia (the PC‐1 pattern) are connected to the multi‐scale variations at intra‐seasonal (3–6 month) and annual (12 month) scales. While calculating the correlation of the PC‐1 with wind fields at 850 hPa from the NCEP/NCAR reanalysis dataset, it is shown that the PC‐1 is closely related to the U and V (horizontal) components over subtropical East Asia and western north Pacific, which well represents East Asian monsoon features. Finally, by comparing the PC‐1 pattern in May between 2003 and 2004, results show that the higher (lower) AOD in 2003 (2004) is associated with weaker (stronger) U component at 850 hPa in middle latitudes over East Asia. Copyright © 2008 Royal Meteorological Society
Tuning of a thunderstorm index for north‐eastern Italy
Authors: Dalla Fontana Alberto
Published: August 2008

In the present study the KO index (KOI) is adapted to the climatology of thunderstorms of north‐eastern Italy. A large data set of events falling into the summer months June, July and August of the years 2003–2007 was collected using imagery from the C‐band radar located in Teolo in the north‐eastern Italian region Veneto, and soundings from the Udine station, located 100 km north‐east of the radar. Three methods were evaluated in order to identify the best use of the KOI as a thunderstorm predictor, i.e. based on (1) maximization of the True Skill Score (TSS), (2) frequency distributions, and (3) a probabilistic approach. The first two methods yield the best use of the KOI for categorical (yes/no) forecasts. The third method defines a forecast probability for each value of the KOI. The forecast probabilities were partially corrected for the negative bias found on a reliability diagram. Resolution has been discussed on a Relative Operating Characteristic (ROC) diagram and compared with the TSS. A more reliable evaluation of the scores could be achieved using an independent data set, which is presently not available. Recommendations are given for an effective use of the findings in the forecasting activity. Copyright © 2008 Royal Meteorological Society
On existence of solutions for a system of Boltzmann transport equations
Authors: Tervo Jouko
Published: August 2008

We consider a linear system of Boltzmann transport equations. The system models charged particle transport in tissue, for example. Although only one species of particles, say photons, is invasing these particles mobilize electrons and positrons. Hence in realistic modelling of particle transport one needs a coupled system of three Boltzmann transport equations. The solution of this system must satisfy the inflow boundary condition. We show existence and uniqueness result of the solution applying coercitivity of the underlying linear operator and its adjoint operator. In addition, we consider existence of continuous solutions by iterative methods. Copyright © 2008 John Wiley & Sons, Ltd.
Welfare benefit promotion within a district general hospital rheumatology centre: A joint project with the local Citizens Advice Bureau
Authors: Fruin Carole , Pitt P.I.
Published: August 2008

Objectives: The Health Assessment Questionnaire (HAQ), used in arthritis provides an overall disability index and has been used previously to indicate those patients with arthritis who may be eligible for welfare benefits such as Attendance Allowance (AA) or Disability Living Allowance (DLA) (Langley et al., 2004, Memel et al., 2002, Powell et al., 2004). The aim of this study was to assess the effectiveness of the HAQ in this local population as a tool for identifying patients who may be eligible for benefits, and to assist those identified in claiming benefits with the help of a Citizens Advice Bureau benefits advisor.

Method: HAQ forms were sent to patients attending the Rheumatology Centre, all those patients with a HAQ score of ≤1.5, indicating moderate to severe disability were contacted initially by telephone by the CAB advisor. Those whom were considered eligible were invited to attend the Rheumatology Centre to determine their suitability to apply for benefit. Suitable patients were invited to complete a department of Work and Pensions claim pack either with the advisor in the Rheumatology Centre, with a CAB form completion volunteer within the patient's home or fill the forms in themselves.

Results: Of the 86 patients contacted by the CAB advisor, 48 were already on benefits, 8 of these patients were advised to have their benefits reviewed. 38 were not in receipt of any benefits. 29 (63%) were awarded benefits.

Conclusions: The HAQ was found to be a useful tool in this local population for identifying patients with arthritis who may be entitled to AA or DLA. The CAB advisor was central to the identification and application process for eligible patients for AA and DLA, which in some cases led to the award of other entitlements. Copyright © 2008 John Wiley & Sons, Ltd.
Rheumatoid arthritis patients' knowledge of the disease and its treatments: A descriptive study
Authors: Mäkeläinen P. , Vehviläinen‐Julkunen K. , Pietilä A‐M.
Published: August 2008

Objective: The purpose of rheumatoid arthritis (RA) patient education is to increase patients' knowledge levels. However, there are only a limited number of studies available concerning these patients' knowledge of their disease and its various treatments. The purpose of this study was to describe RA patients' understanding of their disease and its treatments.

Methods: A total of 252 RA patients participated in this survey in August 2004 (response rate 53.2%). The knowledge levels of the patients and their physical functioning were measured using self‐reported questionnaires. The data were analysed using descriptive and non‐parametric statistical methods.

Results: RA patients' knowledge of the disease and its treatments was, on average, good. However, the total scores of the Patient Knowledge Questionnaire ranged from 2 to 29 (maximum score 30). The patients knew well the aetiology and symptoms of RA, the blood tests and the physical exercise; they knew moderately well the facts relating to joint protection, energy conservation and how to use anti‐rheumatic drugs and non‐steroidal anti‐inflammatory drugs. Young patients, women and patients with a long disease duration knew the most. There was a weak correlation between patient knowledge and physical functioning: the weaker the patient's functioning, the higher the knowledge level.

Conclusions: RA patients' knowledge of their disease and its treatments varied from poor to good in this group. These results can be used for advancing RA patient education. However, more research is needed to evaluate RA patients' knowledge levels. Copyright © 2008 John Wiley & Sons, Ltd.
Disease‐specific measure of quality of life for myasthenia gravis
Authors: Mullins Larry L. , Carpentier Melissa Y. , Paul Robert H. , Sanders Donald B. ,   Muscle Study Group
Published: August 2008

In 2000 a Task Force of the Myasthenia Gravis Foundation of America recommended development of a quality of life (QOL) measure specific for myasthenia gravis (MG). Extant investigations have relied solely on assessment of physical aspects of daily living in conceptualizing QOL, despite research that emphasizes the importance of including psychological factors. In the present study we developed a QOL questionnaire specific to MG (MG‐QOL) that assesses both physical and psychological aspects of function. The MG‐QOL questionnaire was administered as a secondary measure of efficacy in a recently completed prospective trial of mycophenolate mofetil involving 80 MG patients. Comparisons indicated that the MG‐QOL performed better than a nondisease‐specific measure of QOL, the SF‐36, in demonstrating disease change as assessed by the primary measure, the Quantitative MG score (QMG). The MG‐QOL correlated highly with the SF‐36, and demonstrated stronger associations with independent physical ability ratings. Results from this study support the use of this new measure of QOL, both clinically and in treatment trials of MG. Muscle Nerve 38: 947–956, 2008
A role for interleukin‐6 in spreading endothelial cell activation after phagocytosis of necrotic trophoblastic material: implications for the pathogenesis of pre‐eclampsia
Authors: Chen Q , Stone P , Ching L‐M , Chamley L
Published: August 2008

Pre‐eclampsia is characterized by systemic maternal endothelial dysfunction that precedes the onset of clinical symptoms. The cause of the dysfunction is not clear but the number and the nature of trophoblasts shed from the placenta may be altered in pre‐eclamptic pregnancies. These dead trophoblasts become trapped in the pulmonary capillaries and may then be phagocytosed by endothelial cells. Phagocytosis of necrotic, but not apoptotic, trophoblasts results in endothelial cell activation. We have explored the hypothesis that activation can subsequently spread to other endothelial cells via soluble factors without the need for direct contact with shed trophoblasts. Conditioned medium from endothelial cells that had phagocytosed necrotic, but not apoptotic, trophoblasts was shown to activate fresh endothelial cells due, in large part, to IL‐6 secreted into the conditioned medium. The amount of IL‐6 secreted in response to phagocytosis of necrotic trophoblasts was similar to the levels of IL‐6 found by others in the blood of pre‐eclamptic women and was substantially more than the level of IL‐6 which has been reported to induce symptoms of pre‐eclampsia in pregnant rats. We demonstrated that phagocytosis of both a trophoblast cell line as well as trophoblasts shed from human placentae, had this effect on two different types of endothelial cells. The role of IL‐6 in endothelial cell activation was confirmed using recombinant IL‐6 and neutralizing antibodies against IL‐6 and the IL‐6 receptor. Thus, IL‐6 secreted by pulmonary endothelial cells after they have phagocytosed necrotic trophoblasts that are trapped in the pulmonary capillaries could activate endothelial cells in other remote vascular beds, contributing to the systemic activation of the endothelium that is a hallmark of pre‐eclampsia. Copyright © 2008 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Pharmacoepidemiology of QT‐interval prolonging drug administration in critically ill patients
Authors: Freeman Bradley D. , Dixon David J. , Coopersmith Craig M. , Zehnbauer Barbara A. , Buchman Timothy G.
Published: August 2008

Purpose

Commonly prescribed medications produce QT‐prolongation and are associated with torsades de pointes in non‐acutely ill patients. We examined patterns of QT‐prolonging drug use in critically ill individuals.

Methods

An administrative critical care database was utilized to identify patients receiving drugs associated with QT‐interval prolongation or torsades de pointes for ≥ 24 hours.

Results

Data from 212 016 individuals collected over a 63‐month period was examined to identify 6125 patients (2.9%) receiving QT‐interval prolonging drugs. These individuals had a mean (±SE) age of 63.0 (±0.2) years, were predominately male (55.4%) and Caucasian (84.4%), and were exposed to QT‐interval prolonging agents for a mean (±SE) 53.1 (±0.4)% of their ICU length of stay. Respiratory and cardiovascular illnesses were the most common reasons for ICU admission (17.2, 12.0%, respectively). The most frequently administered agents were amiodarone (23.5%), haloperidol (19.8%), and levofloxacin (19.7%); no other single agent accounted for more than 10% of QT‐interval prolonging drugs prescribed. Coadministration of QT‐prolonging drugs occurred in 1139 patients (18.6%). These patients had higher ICU mortality rate and longer ICU lengths of stay, compared to patients not receiving coadministered drugs (p < 0.001 for both). For patients receiving coadministered drugs, overlap occurred for 71.4 (±0.8)% of the time that the drugs were given. Amiodarone coadministration with antibiotics, haloperidol coadministration with antibiotics, and haloperidol coadministration with amiodarone, comprised 15.2, 13.7, and 9.4%, of all coadministered agents, respectively.

Conclusions

QT‐prolonging drugs were used in a minority of critically ill patients. Prospective evaluation in the ICU environment is necessary to determine whether administration of these agents is associated with adverse cardiac events comparable to those reported in ambulatory patients. Copyright © 2008 John Wiley & Sons, Ltd.
Kinetics of interaction of palm ethyl biodiesel with three different polymer materials
Authors: Lutz Giselle , Mata‐Segreda Julio F.
Published: August 2008

Diesel diffuses into neoprene matrices 10% faster than palm ethyl biodiesel at 20°C. In contrast, the palm biodiesel soaks highly plasticized PVC five times faster than diesel. Phthalate plasticizer leaks from the PVC matrix 14 times faster when biodiesel is the absorbed liquid, relative to petrodiesel. This biodiesel penetrates polybutadiene‐styrene resins at rates that depend on the ratio of phenyl to CHCH units in the resins. Copyright © 2008 John Wiley & Sons, Ltd.
Blends of carbon blacks and multiwall carbon nanotubes as reinforcing fillers for hydrocarbon rubbers
Authors: Bokobza Liliane , Rahmani Mostafa , Belin Colette , Bruneel Jean‐Luc , El Bounia Nour‐Eddine
Published: August 2008

The reinforcement of a styrene‐butadiene rubber (SBR) by single fillers—carbon black (CB) or multiwall carbon nanotubes (MWNTs)—or by mixtures of CB and MWNTs, is investigated. The morphologies, mechanical and electrical properties of the composites, are analyzed. A significant improvement in the tensile properties is observed for samples containing a dual phase. Using atomic force (AFM) and transmission electron (TEM) microscopies, we demonstrate that the double loading improves the dispersion of the nanotubes in SBR. Electrical measurements show lower resistivity and a lower percolation threshhold for composites containing blends of fillers, which provides further evidence of better dispersion. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 46: 1939–1951, 2008
Creep behavior of ultra‐thin polymer films
Authors: O'Connell Paul A. , Hutcheson Stephen A. , McKenna Gregory B.
Published: August 2008

A novel microbubble inflation method has been used to determine the creep compliance of poly(vinyl acetate) and polystyrene ultra‐thin films (13–300 nm thick) at temperatures from below to above the glass temperature. We present results that suggest that time‐temperature and time‐thickness superposition hold in the glassy relaxation regime. Although time‐temperature superposition is found for the entire response curve for each thickness, we also find that time‐thickness superposition fails as the long‐time compliance is approached. This effect occurs because of a strong stiffening as the film thickness decreases. We also show first evidence of stiffening in the glassy regime of free standing films of polystyrene. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1952–1965, 2008
Assessing crystalline lamellae orientation impact on the properties of semi‐crystalline polymer‐clay nanocomposites
Authors: Vermogen A. , Picard E. , Milan M. L. , Masenelli‐Varlot K. , Duchet J. , Vigier G. , Espuche E. , Gérard J. F.
Published: August 2008

Semi‐crystalline polymer‐clay nanocomposite properties are often considered only by their clay dispersion state. The purpose of this work is to highlight texture effects on semi crystalline polymer‐clay properties. Maleic anhydride‐grafted polyethylene nanocomposites with two different processing techniques (Blown Extrusion and Compression) were studied. The processing was shown to induce different crystalline lamellae orientation in the films but with no significant changes in the crystalline lamellae long period, degree of crystallinity, clay particle orientation morphology and dispersion. The impact of these specific textures on the nanocomposites barrier and tensile properties were reported. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1966–1975, 2008
Migration of nanosilica particles in polymer blends
Authors: Elias L. , Fenouillot F. , Majesté J.‐C. , Martin G. , Cassagnau P.
Published: August 2008

Hydrophilic pyrogenic silica melt mixed in immiscible polypropylene/poly (ethylene‐co‐vinyl acetate) (PP/EVA) blend was found to migrate from the PP matrix to the EVA dispersed domains and remained confined inside them. Surprisingly, it was shown than silica was also able to migrate from a dispersed PP phase to an EVA matrix but this transfer was slower and not complete. The same silica with a hydrophobic surface treatment moved and accumulated to the blend interface and in PP. The mechanisms from which this migration proceeds are discussed. Whereas self diffusion of the particles was shown to have almost no effect, shear induced movements and collisions with dispersed drops is believed to be the most efficient mechanism. The possible trapping of silica aggregates during droplet–droplet coalescence was impossible to observe but is thought to be a possible additional mechanism. No quantification on the relative importance of the latter phenomenon can be drawn at the moment. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1976–1983, 2008
Positron annihilation lifetime measurements of mechanically fatigued polystyrene samples
Authors: Erichsen J. , Nagel C. , Günther‐Schade K. , Renner M. , Altstädt V. , Faupel F.
Published: August 2008

Early stages of cyclic fatigue‐loaded polystyrene (PS) specimens were investigated by positron annihilation lifetime spectroscopy (PALS) at a maximum stress amplitude of 15 MPa. PALS yields information about the average unoccupied hole volume. A linear increase in the ortho‐positronium (o‐Ps) lifetime was observed in a range from 0 to 50,000 cycles. This increase occurs homogeneously distributed at different positions along a sample of 170 mm. The average unoccupied void volume increases by 1.2%. On the other hand, the o‐Ps intensity shows no systematic change upon cycling. The results suggest a homogeneous and linear increase in free volume prior to craze formation. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1991–1995, 2008
Synthesis, characterization and optical properties of nanocrystalline lead molybdate
Authors: Anandakumar V. M. , Khadar M. Abdul
Published: August 2008

Lead molybdate (PbMoO4) finds wide practical application due to its acousto‐optic and luminescent properties. In the present study, nanoparticles of PbMoO4 of different grain sizes were synthesized through chemical precipitation technique. Precipitation reactions carried out in non‐aqueous media below room temperature were used for the synthesis of samples of two lower grain sizes. The crystal structure and grain size of the samples were determined using X‐ray diffraction and transmission electron microscopy. UV–Visible absorption spectra showed a broad absorption peak for the sample with average grain size of 52 nm which is blue shifted considerably as the average grain size was reduced to 14 nm. The fundamental absorption follows an exponential edge indicating Urbach‐like behaviour. The temperature dependence of Urbach parameter is also determined. The micro‐Raman spectra and FT Raman spectra of the samples were recorded and the features in the Raman spectra are discussed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of thallium doping on the electrical and optical properties of CdO thin films
Authors: Dakhel A. A.
Published: August 2008

A series of lightly Tl‐doped CdO thin films (1%, 1.5%, 2%, 2.5%, and 3%) have been prepared by a vacuum evaporation method on glass and Si wafer substrates. The prepared films were subjected to structural study by X‐ray diffraction, optical characterisation by UV–VIS–NIR absorption spectroscopy, and dc‐electrical measurements. Experimental data indicate that Tl3+ doping slightly stretching stresses the CdO crystalline structure and changes the optical and electrical properties. It was observed that Tl doping widens the energy gap of CdO from 2.22 eV to 2.83 eV via a Burstein–Moss energy level shift. The band gap shrinkage was also observed for carrier concentrations Nel > 1.13 × 1020 cm–3, which was explained by merging of the impurity band with the conduction band. The optical properties were explained by using Hamberg et al.'s band‐to‐band transitions and classical Drude theory. The electrical behaviour of the samples shows that they are degenerate semiconductors. The 2% Tl‐doped CdO sample shows an increase in its mobility by about 1.4 times, conductivity by 5 times, and carrier concentration by 3.6 times relative to the undoped CdO film. From the transparent‐conducting‐oxide point of view, Tl is sufficiently effective for CdO doping but does not emulate other dopants like In, Sn, Sc, and Y. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Polymer microfibers obtained using porous silicon templates
Authors: Marsal L. F. , Formentín P. , Palacios R. , Trifonov T. , Ferré‐Borrull J. , Rodriguez A. , Pallarés J. , Alcubilla R.
Published: August 2008

The deposition of specific materials into ordered pores arranged in a regular lattice allows the fabrication of ordered fiber arrays. Porous silicon is an attractive candidate for use as a template because the porosity and pore size can be tuned. Polymer microfibers using macroporous silicon with various pore depths as template system is reported here. The method entails vacuum infiltration of a polymer solution into the pores of the template. Two different types of polymer were selected in order to obtain ordered arrays of fibers made from Poly(methyl) methacrylate) or Poly(dimethylsiloxane). Microtubes were obtained when we used a silicon membrane as a template, whereas microfibers were obtained when we used a silicon template with pores opened only at one end. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electrical characteristics of temperature‐difference liquid phase deposited SiO2 on GaN with (NH4)2Sx treatment
Authors: Lee Ming‐Kwei , Ho Chen‐Lin , Zeng Jia‐Yi
Published: August 2008

The characteristics of a SiO2 film grown on (NH4)2Sx treated GaN by temperature‐difference liquid phase deposition were investigated. Hydrofluorosilicic acid and boric acid were used as deposition solutions. For GaN without the (NH4)2Sx treatment, an Al/SiO2/GaN MOS diode shows poor electrical characteristics due to the native oxides existing at the interface. With (NH4)2Sx treatment of GaN, a stable sulfide‐terminated surface is obtained and the leakage current density of SiO2/GaN is improved from 6.15 × 10–4 A/cm2 to 2.08 × 10–5 A/cm2 at the electric field of 2 MV/cm. The effective oxide charges decrease from 6.09 × 1011 C/cm2 to 2.23 × 1011 C/cm2. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Direct bonding conditions of ferrite garnet layer on ion‐exchanged glass waveguides
Authors: Joudrier Anne‐Laure , Couchaud Maurice , Moriceau Hubert , Broquin Jean‐Emmanuel , Ferrand Bernard , Deschanvres Jean‐Luc
Published: August 2008

In order to realize an integrated optical isolator, a new hybrid optical structure has been proposed. This structure is composed of an active magneto‐optic garnet layer with a strong refractive index, transferred on a passive ion‐exchanged glass waveguide. Given the thermal restraints relating to the stability of the glass waveguides, the process used to achieve this hybrid structure is composed of two main steps: firstly, good quality garnet films were grown by liquid phase epitaxy, then these active films were bonded successfully on glass wafer. According to modelling, the thickness of the garnet layer does not exceed 300 nm for maintaining a good confinement. Good wafer bondings on ion‐exchanged glass waveguides are obtained. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Preparation of Heusler thin films: The quaternary alloy Co2Fe0.5Mn0.5Si
Authors: Ebke D. , Thomas A. , Hütten A. , Balke B. , Felser C. , Schmalhorst J. , Reiss G.
Published: August 2008

In this work the basic strategies for the preparation of Co2Mn0.5Fe0.5Si as an example for Heusler alloy thin films will be described. Texture and magnetic properties of these films will be discussed, especially with regard to different buffer layers and annealing temperatures. Finally, we will show the integration of Heusler thin films into magnetic tunnel junctions (MTJs) and calculate the effective spin polarization. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influences of partial melting and overheating on amorphization of Ge2Sb2Te5 during the reset process
Authors: Youm Min Soo , Kim Yong Tae , Sung Man Young
Published: August 2008

It is very important to observe the change in the atomic structure of melt‐quenched amorphous Ge2Sb2Te5 (GST) to discover the failure mechanism of phase‐change random access memory (PRAM) devices during the reset process. We fabricated the phase‐change devices and measured the initial resistance changes with various reset pulse amplitudes. For the observation of the atomic structure changes of GST thin films, we designed the specimens for transmission electron microscopy (TEM) and annealed them below and above the melting temperature of GST (Tm = 650 °C) before quenching. The annealed‐and‐quenched GST at 630 °C has a hexagonal structure with a grain size of about 10 nm after the partial melting. The annealed‐and‐quenched GST at 750 °C also has a hexagonal structure because of the latent heat. The observed atomic structures of GST are in accordance with the resistance changes inferred from the fabricated edge‐contact type of PRAM cell. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of vacancies on copper precipitation in n‐type Czochralski silicon
Authors: Wang Weiyan , Yang Deren , Ma Xiangyang , Que Duanlin
Published: August 2008

The effect of vacancies induced by the prior rapid thermal processing (RTP) at 900–1200 °C in Ar on copper (Cu) precipitation in n‐type silicon has been investigated by means of optical microscopy and transmission electron microscopy. It was revealed that in the sample without the prior RTP, the Cu precipitates appeared as spheres with sizes of about 100 nm and, moreover, induced stress in the matrix. In this case, they were preferentially delineated as etch pits. Whereas, for the samples with the prior RTP at 1000 °C and above, the Cu‐precipitate colonies, in which a number of sphere‐like Cu precipitates with sizes of 10–20 nm assembled on and around the climbing dislocations, formed with different depth profiles dependent on the prior RTP temperature. The formation of Cu‐precipitate colonies and their depth profile were tentatively explained in terms of the induced vacancies and their related defects. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synthesis and detailed kinetic analysis using computerized glow‐curve deconvolution technique of nanocrystalline Sr3Al2O6:Pr3+ – A new phosphor for UV applications
Authors: Sharma Suchinder K. , Pitale Shreyas S. , Malik M. Manzar , Dubey R. N. , Qureshi M. S.
Published: August 2008

Pr3+‐doped nanocrystalline Sr3Al2O6 phosphor, synthesized through solution combustion route and calcined at 1100 °C is reported in this paper. The crystallinity checks followed by phosphorescence decay studies were performed to define the decaying rates of the present phosphor system. Thermoluminescence studies after UV‐irradiation were performed at room temperature and the glow peak obtained possesses three well‐defined temperature maxima at 383.75 K, 428 K and 509 K. Tm–Tstop and the repeated initial rise method (RIR) is applied to estimate approximate peak positions and the energy values for computerized glow‐curve deconvolution. The nonshifting Tm property is applied to define the order of kinetics. The calculated activation energy after deconvolution lies between 0.72 eV and 1.28 eV distributed into eight different levels. The frequency factor is of the order of 109 s–1 to 1011 s–1. The figure of merit for deconvolution is 1.6%. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Focused‐ion‐beam fabrication of ZnO nanorod‐based UV photodetector using the in‐situ lift‐out technique
Authors: Lupan Oleg , Chow Lee , Chai Guangyu , Chernyak Leonid , Lopatiuk‐Tirpak Olena , Heinrich Helge
Published: August 2008

ZnO nanorods and nanowires are promising candidates as new types of high‐sensitivity ultraviolet (UV) photodetectors due to their wide bandgap and large aspect ratio. In this study, single‐crystalline ZnO nanorods were grown on glass substrates by a hydrothermal method. Specific structural, morphological, electrical, and optical measurements were carried out. A single ZnO nanorod‐based photodetector was fabricated using the in‐situ lift‐out technique in a focused ion beam (FIB/SEM) instrument and characterized. With a source wavelength of 370 nm and an applied bias of 1 V, the responsivity of the ZnO nanorod is 30 mA/W. The single ZnO nanorod photodetector exhibits an ultraviolet (UV) photoresponse promising for potential applications as cost‐effective UV detectors. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A better understanding of the growth mechanism of Zn(S,O,OH) chemical bath deposited buffer layers for high efficiency Cu(In,Ga)(S,Se)2 solar cells
Authors: Hubert C. , Naghavi N. , Etcheberry A. , Roussel O. , Hariskos D. , Powalla M. , Kerrec O. , Lincot D.
Published: August 2008

In the field of Cu(Ga,In)(S,Se)2 photovoltaic technology, zinc sulphide based buffer layers prepared by Chemical Bath Deposition (CBD) have already demonstrated their potential to replace CdS. This paper aims on a better understanding of deposition mechanism of the Zn(S,O,OH) buffer layers. First, the influence of deposition parameters is studied from solution chemistry considerations by constructing solubility diagrams of ZnS, ZnO, and Zn(OH)2. Experimental studies are then carried out by the in situ quartz crystal microgravimetry (QCM) technique. A global equation for the growth rate is derived from these experiments. The morphology and composition of Zn(S,O,OH) films are then determined using scanning electron microscopy and X‐ray photoelectron spectroscopy techniques. Electro‐deposited‐CIS/Zn(S,O,OH)/ZnO and co‐evaporated‐CIGS/Zn(S,O,OH)/ZnO cells were prepared with efficiencies similar to that of reference CBD CdS buffer layers. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Improved cognitive performance after dietary supplementation with a Pinus radiata bark extract Formulation
Authors: Pipingas Andrew , Silberstein Richard B. , Vitetta Luis , Rooy Cindy Van , Harris Elizabeth V. , Young Joanna M. , Frampton Christopher M. , Sali Avni , Nastasi Joseph
Published: August 2008

Dietary interventions may have the potential to counter age‐related cognitive decline. Studies have demonstrated an improvement in age‐related cognitive impairment in animals after supplementation with plant extracts containing flavonoids but there are few human studies. This double‐blind, controlled study examined the effects on cognitive performance of a 5 week supplementation with Enzogenol® Pinus radiata bark extract containing flavonoids, in 42 males aged 50–65 years, with a body mass index >25. Participants were supplemented for 5 weeks either with Enzogenol® plus vitamin C, or with vitamin C only. A battery of computerized cognitive tests was administered, and cardiovascular and haematological parameters were assessed prior to and following supplementation. The speed of response for the spatial working memory and immediate recognition tasks improved after supplementation with Enzogenol® plus vitamin C, whereas vitamin C alone showed no improvements. A trend in a reduction of systolic blood pressure was observed with Enzogenol® plus vitamin C, but not with vitamin C alone. The blood safety parameters were unchanged. The findings suggest a beneficial effect of supplementation with Enzogenol® on cognition in older individuals. Larger studies are needed to ascertain its potential as a preventive treatment for age‐related cognitive decline. Copyright © 2008 John Wiley & Sons, Ltd.
Antiplatelet activities of newly synthesized derivatives of piperlongumine
Authors: Park Byeoung‐Soo , Son Dong‐Ju , Choi Won‐Sik , Takeoka Gary R. , Han Sung Ok , Kim Tae‐Wan , Lee Sung‐Eun
Published: August 2008

Piperlongumine, a pyridone alkaloid isolated from Piper longum L., exhibited a potential inhibitory effect on washed rabbit platelet aggregation induced by collagen, arachidonic acid (AA) and platelet activating factor (PAF), without any inhibitory effect on that induced by thrombin. Piperlongumine was used as a lead compound for the synthesis of new antiplatelet agents. Seven synthetic compounds were newly synthesized from 3,4,5‐trimethoxycinnamic acid (TMCA). They were 1‐piperidin‐1‐yl‐3‐(3,4,5‐trimethoxy‐phenyl)prop‐2‐en‐1‐one (1′), 1‐morpholin‐4‐yl‐3‐(3,4,5‐trimethoxyphenyl)prop‐2‐en‐1‐one (2′), 1‐(3,5‐dimethylpiperidin‐1‐yl)‐3‐(3,4,5‐trimethoxyphenyl)prop‐2‐en‐1‐one (3′), 1‐(2‐methylpiperidin‐1‐yl)‐3‐(3,4,5‐tri‐methoxyphenyl)prop‐2‐en‐1‐one (4′), 1‐(3‐hydroxypiperidin‐1‐yl)‐3‐(3,4,5‐trimethoxyphenyl)‐ prop‐2‐en‐1‐one (5′), 1‐[3‐(3,4,5‐tri‐methoxyphenyl) acryloyl]‐piperidin‐2‐one (6′) and ethyl 1‐[3‐(3,4,5‐trimethoxyphenyl)‐acryloyl]piperidine‐4‐carboxylate (7′). Among those seven synthetic derivatives, 1‐(3,5‐dimethylpiperidin‐1‐yl)‐3‐(3,4,5‐trimethoxyphenyl)prop‐2‐en‐1‐one (3′) had the most inhibitory effect on platelet aggregation induced by collagen, AA and PAF. Copyright © 2008 John Wiley & Sons, Ltd.