bluuebunny/crossref_metadata_2025 huggingface dataset:
Fluoride-induced interleukin-6 and interleukin-8 synthesis in human epithelial lung cells
Authors: Refsnes M , Becher R , Låg M , Skuland T , Schwarze P E
Published: April 2003

Exposure to fluorides has been associated with asthmatic symptoms among workers in the aluminium industry. In a recent experimental study hydrogen fluoride (HF) was found to induce a weak inflammatory response in humans. In the present study the potential of sodium fluoride (NaF) and HF to induce cytokine response was examined and how these responses are modulated by Al3+ in a human epithelial lung cell line (A549). Dose-response experiments showed a maximal release of IL-6 and IL-8 at a concentration of 5 mM NaF 24 h after addition. The responses to HF were of a similar magnitude as for NaF. Time-course experiments showed a NaF-induced IL-6 response at 5 h, whereas an IL-8 response was observed after 10 h. Cycloheximide treatment completely abolished the NaF-induced cytokine responses. A marked increase in the mRNA level for IL-6 was observed already 2 h after exposure to 5 mM NaF, and presumably is a prerequisite for the subsequent increase of IL-6. The fluoride-induced effects on IL-6 and IL-8 release were strongly reduced by pretreatment with deferoxamine (an Al3+-chelator), and enhanced by addition of Al3+. This indicates that an AlF47-complex, a known activator of GTP-binding proteins, is involved in fluoride-induced IL-6 and IL-8 responses in A549 cells.
Detection of germ cell genotoxic potential, of carbon disuiphide using sperm head shape abnormality test
Authors: Kumar S , Patel K G , Gautam A K , Agarwal K , Shah B A , Saiyed H N
Published: April 2003

1 Adult male albino rats (CF Strain) were administered i.p. CS2 dissolved in cotton seed oil at doses of 25, 50, 100 and 200 mg/kg b.wt. for a period of 60 days. Effect of CS, on epididymis, adrenal weight, sperm count and sperm head shape abnormality was studied. 2 Epididymal weight remained unaltered in 25, 50 and 100 mg/kg CS2 treated groups, whereas in highest dose of CS2 treated (200 mg/kg) group a non-significant reduction in epididymis weight was observed. A slight increase in adrenal weight was observed in lower doses groups (25 and 50 mg/kg) while a considerable decrease in adrenal weight was noted in highest dose (200 mg/kg) of CS, treated group in the present study. 3 An increase in sperm head shape abnormality and decrease in sperm count was observed in all the CS2 treated groups. However, the changes were statistically significant only after higher dose of CS2 treatment as compared to control. 4 This study suggests that CS2 may have the potential to induce adverse effects on male reproductive system of rats. Sperm head shape abnormality assay used in this study also elicits germ cell genotoxic potential of carbon disulphide.
Passive smoking exposure of sick children in Hong Kong
Authors: Chan Sophia SC , Lam Tai Hing , Betson Carol L
Published: April 2003

1 This study aims to investigate the extent of passive smoking exposure of sick children in Hong Kong; their father' smoking behaviors and their mother' action to protect the child from environmental tobacco smoke (ETS). 2 This cross-sectional survey was the first phase of a randomized controlled trial on a health education intervention provided by nurses in the general paediatric wards of four major hospitals in Hong Kong. The subjects are non-smoking mothers of sick children admitted to hospital and with a smoking husband living together in the same household with the child. Eligible subjects completed a self-administered baseline questionnaire before entering into the trial. 3 All the 848 children whose mothers completed the questionnaire during December 1997 to April 1998 had a smoking father. They constituted about 24% (95% CI: 22.6-24.9%) of all the sick children during the same period. More than half of the children' fathers (55%; 51.6-58.3%) smoked 1-14 cigarettes per day and about 68% (64.7-71.0%) of them were daily smokers for over 10 years. Over half (53%; 49.4-56.2%) of the fathers smoked 1-14 cigarettes at home every day. About 21% of the fathers smoked near the child occasionally and 31% (27.4-33.6%) smoked 1-14 cigarettes near the child per day. About 16% of the children lived with more than one smoker (2-3). About 86% (83.3-88.0%) of the children had 1-3 smokers who smoked at home and 61% (58.1-64.7%) of them had 1-3 smokers who smoked near them every day. However, 70% ofthe children were reported by their mothers as exposed to ETS at home. This percentage (70%) was less than the percentage (86%) of smokers who smoked at home daily. About 31.1% of the mothers reported symptoms of coughing and running nose (20.6%) in their children when they were exposed to ETS. To protect the child from ETS exposure, 43% of the mothers requested the father not to smoke near the child, 33.1% requested the father to smoke less cigarettes and 31.5% advised the father to quit smoking. 4 In conclusion, sick children in Hong Kong are at risk of exposure to ETS, but not all mothers are aware of the health risks and their actions were inadequate. There is a critical need to promote awareness of ETS exposure and the health risks in the family in Hong Kong so as to reduce illness and hospital admission in children.
Low level saliva cotinine determination and its application as a biomarker for environmental tobacco smoke exposure
Authors: Phillips Keith , Bentley Mark C , Abrar Mohammed , Howard David A , Cook Jeremy
Published: April 2003

1 The determination of personal exposures to environmental tobacco smoke (ETS) and respirable suspended particles (RSP) for housewives, and fixed site monitoring of their homes, have been undertaken by these authors throughout Europe, South East Asia and Australia. Median 24 h time weighted average (TWA) concentrations for ETS particles and nicotine were found to be significantly higher for housewives living in smoking households compared with those living in nonsmoking households. For Europe, median TWA concentrations of 4.1 and <0.26 sg/m3 for ETS particles and 0.63 and < 0.08 ig/m3 for nicotine were found for housewives living in smoking and nonsmoking households respectively. 2 In addition to the measurement of RSP, ETS particles and nicotine, saliva cotinine concentrations were determined using a radioimmunoassay method with a limit of quantitation of 1 ng/ml. Median saliva cotinine concentrations of 1.4 and <1 ng/ml were determined for European housewives living in smoking and nonsmoking households respectively, which reflected the poor limit of quantitation of this methodology. A chromatographic method utilising tandem mass-spectrometric detection was developed and validated for the determination of both cotinine and 3-hydroxycotinine, two of the main metabolites of nicotine, with lower limits of quantitation of 0.05 and 0.10 ng/ml respectively. This method was applied to samples collected from subjects with a known ETS exposure history and median cotinine concentrations of <0.05 ng/ml for self-reported unexposed nonsmokers, 0.65 ng/ml for nonsmokers reporting some ETS exposure and 1.28 ng/ml for nonsmokers living with smokers were found. 3 In conclusion, the measurement of RSP and ETS concentrations derived from personal or fixed site monitors for housewives may provide some indication of potential exposures to dependent children. The recent development and application of a highly sensitive assay for the determination of cotinine in saliva has provided evidence to suggest that concentrations determined at sub-nanogram levels may be used as a biomarker for ETS exposure. This improved methodology, coupled with non-invasive sampling for saliva, may be of significance when considering the application of cotinine as a biomarker for ETS exposure in children.
Cardiovascular and neurological toxicity of venlafaxine
Authors: Blythe David , Hackett L Peter
Published: April 2003

1 We report a case of venlafaxine overdose and describe pharmacokinetic data on drug disposition. 2 Case report. Serial venlafaxine levels were measured and drug half-life calculated and compared to data at therapeutic concentrations. Metabolite concentrations were also measured and the potential for toxicity described with reference to individual variation in such metabolism 3 Venlafaxine can cause significant cardiac and neurotoxicity. Its potential for causing such toxicity may be dependent on whether an individual has the extensive metaboliser cytochrome CYP2D6 phenotype or the poor metaboliser phenotype
Acute airway effects of formaldehyde and ozone in BALB/c mice
Authors: Nielsen G Damgård , Hougaard K S , Larsen S T , Hammer M , Wolkoff P , Clausen P A , Wilkins C K , Alarie Y
Published: April 2003

1 Concentration and time-effect relationships of formaldehyde and ozone on the airways were investigated in BALB/c mice. The effects were obtained by continuous monitoring of the respiratory rate, tidal volume, expiratory flow rate, time of inspiration, time of expiration, and respiratory patterns. 2 With concentrations up to 4 p.p.m., formaldehyde showed mainly sensory irritation effects of the upper airways that decrease the respiratory rate from a trigeminal reflex. The no-effect level (NOEL) was about 0.3 p.p.m. This value is close to the human NOEL, which is about 0.08 p.p.m. 3 Ozone caused rapid, shallow breathing in BALB/c mice. Later on, the respiratory rate decreased due to another vagal response that indicated an incipient lung oedema. The NOEL in mice was about p.p.m. during 30 min of ozone exposure. No major effect occurs in resting humans at about 0.4 p.p.m. 4 Thus, the upper airway irritant, formaldehyde, and the deep lung irritant, ozone, showed the same types of respiratory effects in humans and in BALB/c mice. Also, the sensitivity was nearly identical. Continuous monitoring of respiratory effects in BALB/c mice, therefore, may be a valuable method for the study of effects of other environmental pollutants, which, however, should be confirmed in further studies.
Haemotoxicity of chloramphenicol succinate in the CD-1 mouse and Wistar Hanover rat
Authors: Turton J A , Yallop D , Andrews C M , Fagg R , York M , Williams T C
Published: April 2003

1 Chloramphenicol has been widely used in the treatment of serious infections including typhoid fever and meningitis. However, the drug is haemotoxic in man inducing firstly, a reversible, dose-dependent anaemia which develops during treatment, secondly, an often fatal aplastic anaemia with pancytopenia and acellular marrow, and thirdly, leukaemia. 2 We investigated the haemotoxicity of chloramphenicol succinate (CAPS) in female CD-1 mice in repeat dose studies, to compare the response with the reversible anaemia reported in man. Studies in male Wistar Hanover rats were also carried out. 3 CAPS was gavaged daily to mice at dose levels from 800–2000 mg/kg for seven days. Values were significantly reduced for reticulocytes at 1700 and 2000 mg/ kg, and for erythrocytes (RBC), haematocrit (HCT), and haemoglobin (Hb) at 2000 mg/kg. Platelet and white blood cell (WBC) counts were unaffected. 4 Mice were dosed with CAPS at 1400 mg/kg for 10 days and sampled at 1, 4 and 15 days after the last dose. At day 1 post dosing, RBC, HCT and Hb values were significantly reduced, but returned to normal (or above normal) by day 4 or 15. 5 CAPS from 2000–4000 mg/kg was gavaged to rats daily for 19 days. Hb values were significantly lower at 3600 and 4000 mg/kg; reticulocytes were not reduced. WBC and platelet counts, in general, were unaffected. 6 Levels of apoptosis in marrow mononuclear cells were increased in CAPS-treated mice, but not in CAPS-treated rats. Serum biochemistry parameters, in general, showed few changes of toxicological significance. 7 We conclude that the administration of CAPS to CD-1 mice induced haematological changes showing close parallels with the chloramphenicol-induced reversible anaemia seen in man.
Effects of Hypothalamic Neuropeptides on Extracellular Signal-Regulated Kinase (ERK1 and ERK2) Cascade in Human Tumoral Pituitary Cells
Authors: Lania A. , Filopanti M. , Corbetta S. , Losa M. , Ballaré E. , Beck-Peccoz P. , Spada A.
Published: April 2003

The G protein-coupled receptor (GPCR) activation has been demonstrated to affect the ERK1/2 cascade in different cell lines. We investigated the effects of hypothalamic neuropeptides acting via GPCR on this pathway in GH-secreting (GH-oma) and nonsecreting (NFPA) pituitary adenomas. GHRH increased ERK1/2 activity (236 ± 80%) in both gsp− and gsp+ GH-omas, this effect being almost completely abolished by protein kinase C (PKC) blockade. Both GnRH and pituitary adenylate-activating peptide caused a similar PKC-dependent activation of ERK1/2 in most NFPA. Increasing cAMP by forskolin caused a protein kinase A-dependent increase of ERK activity (287 ± 37%) in GH-omas and had no effect in NFPA. ERK cascade blockade in GH-omas did not affect basal and GHRH-stimulated GH release, whereas it totally prevented the 3-fold increase in cyclin D1 protein expression induced by GHRH. In conclusion, this study demonstrated that in pituitary adenomas the activation of GPCR by neurohormones caused a PKC-dependent activation of ERK1/2 cascade that, at least in GH-omas, resulted to be involved in cyclin D1 induction by GHRH. Moreover, a stimulatory effect of the protein kinase A-dependent pathway on ERK1/2 cascade occurred selectively in GH-omas, probably contributing to the mitogenic potential of the cAMP pathway in this cell type.
Molecular Genetics of 3β-Hydroxy-Δ5-C27-Steroid Oxidoreductase Deficiency in 16 Patients with Loss of Bile Acid Synthesis and Liver Disease
Authors: Cheng Jeffrey B. , Jacquemin Emmanuel , Gerhardt Marie , Nazer Hisham , Cresteil Danièle , Heubi James E. , Setchell Kenneth D. R. , Russell David W.
Published: April 2003

The 3β-hydroxy-Δ5-C27-steroid oxidoreductase (C27 3β-HSD) is a membrane-bound enzyme of the endoplasmic reticulum that catalyzes an early step in the synthesis of bile acids from cholesterol. Subjects with autosomal recessive mutations in the encoding gene, HSD3B7, on chromosome 16p11.2–12 fail to synthesize bile acids and develop a form of progressive liver disease characterized by cholestatic jaundice and malabsorption of lipids and lipid-soluble vitamins from the gastrointestinal tract. The gene encoding the human C27 3β-HSD enzyme was isolated previously, and a 2-bp deletion in exon 6 of HSD3B7 was identified in a well characterized subject with this disorder. Here, we report a molecular analysis of 15 additional patients from 13 kindreds with C27 3β-HSD deficiency. Twelve different mutations were identified in the HSD3B7 gene on chromosome 16p11.2–12. Ten mutations were studied in detail and shown to cause complete loss of enzyme activity and, in two cases, alterations in the size or amount of the transcribed mRNA. Mutations were inherited in homozygous form in 13 subjects from 10 families and compound heterozygous form in four subjects from three families. We conclude that a diverse spectrum of mutations in the HSD3B7 gene underlies this rare form of neonatal cholestasis.
Kinetic Deuterium Isotope Effect in Single-Electron Transfer Occurring from Tributylphosphine to Viologens
Authors: Yasui Shinro , Itoh Kenji , Ohno Atsuyoshi , Tokitoh Norihiro
Published: April 2003

Single electron transfer (SET) takes place from tributylphosphine (1) to 1-methyl-1′-alkyl-4,4′-bipyridinium salts (viologens; 2) in acetonitrile–methanol. Significant kinetic deuterium isotope effect has been observed with respect to hydrogens of a methyl (or an ethyl) substituent in 2. The results are interpreted in terms of SET occurring within a tight encounter complex formed between 1 and 2.
GaCl3-Promoted Ethenylation of Thioester Silyl Enolate and Dienolate with Silylethyne
Authors: Arisawa Mieko , Miyagawa Chie , Yoshimura Satoru , Kido Yoshiyuki , Yamaguchi Masahiko
Published: April 2003

In the presence of GaCl3, silyl enol ethers derived from either S-alkyl or S-aryl thioesters are ethenylated at the α-carbon atom with trimethylsilylethyne in high yields. The reactions of dienolates give α,α-diethenyl thioesters.
Oxidative Ligand Coupling of Tetraarylborates Promoted by Chlorosilane and Molecular Oxygen
Authors: Sakurai Hidehiro , Morimoto Chihiro , Hirao Toshikazu
Published: April 2003

Oxidative ligand coupling of organoborates is promoted by chlorosilane and molecular oxygen. When tetraarylborate compounds are treated with Ph2SiCl2 or PhSiCl3 in acetonitrile under an oxygen atmosphere, the corresponding biaryls are obtained in good yields. Use of unsymmetrical borates results in the selective formation of unsymmetrical biaryls.
Reactivities of Triethylgermylborate in Methanol
Authors: Nanjo Masato , Matsudo Kazuhiko , Mochida Kunio
Published: April 2003

The reactivity of lithium (triethylgermyl)triphenylborate, prepared from unsolvated triethylgermyllithium and triphenylborane, with organic substrates in methanol was investigated. The germylborates reacted with organic halides and acyl halides to give the corresponding germyl-substituted compounds. From the reaction with carbonyl compounds, esters, carboxylic acid, alkenes, and alkynes, germylborates were completely recovered.
1-Aryl-Substituted Cage Molecules ArC(SiMe2SiMe2)3CR: Preparation, Properties, and Application to Liquid Crystalline Compounds
Authors: Shimizu Masaki , Watanabe Kotaro , Nakagawa Hisashi , Becker Torsten , Sugimoto Susumu , Hiyama Tamejiro
Published: April 2003

Phenyl groups were successively introduced at the bridgehead positions of cage compound HC(SiMe2SiMe2)3CH via deprotonation–cyclohexenylation–dehydrogenation. UV absorption spectra of the cage compounds suggested the possibility of electronic interaction between the cage and aromatic moieties. Bromination of the phenylated cage molecule gave a p-bromo derivative that was transformed to liquid crystalline compounds.
Dichloromethane Activation by Chlorochromium(II) Complexes with TpiPr2: Generation of an Electrophilic Cr–Methylene Species without the Action of an External Cl-Abstraction Reagent
Authors: Sugawara Ken-ichiro , Hikichi Shiro , Akita Munetaka
Published: April 2003

Five-coordinated chlorochromium(II) complexes with TpiPr2 activate CH2Cl2 to give a metal–carbene species without the action of an external Cl-abstraction reagent, and the resulting methylene fragment is trapped by nucleophiles such as pyrazole, pyridine and olefin.
Fabrication of Hierarchically Structured Zeolites through Layer-by-Layer Assembly of Zeolite Nanocrystals on Diatom Templates
Authors: Wang Y J , Tang Y , Wang X D , Dong A G , Shan W , Gao Z
Published: April 2003

Zeolites with hierarchical structure were prepared through layer-by-layer electrostatic assembly of zeolite nanocrystals on the diatom substrate. The thickness and composition of the zeolite coatings on the diatom could be readily tailored by varying the number of deposition cycles and the zeolite types used, respectively.
Nondestructive Real-Time Monitoring of the Redox Status in a Potted Plant by Using a Surface-Coil-Type ESR Resonator
Authors: Tada Mika , Shiraishi Takuo , Yokoyama Hidekatsu , Ohya Hiroaki , Ogata Tateaki , Kamada Hitoshi
Published: April 2003

To perform nondestructive real-time monitoring of the redox state in plants against environmental stress, a 700-MHz surface-coil-type ESR resonator was employed and temporal changes in ESR signals of an exogenous nitroxide radical in the leaves of a potted tobacco plant were observed after chilling. ESR signals of the nitroxide radical were barely observed at room temperature, indicating that the nitroxide radical was reduced to the hydroxylamine by reductants in the leaves. Chilling significantly increased the signal-to-noise ratios (S/Ns) of the nitroxide radical in the leaves. Because hydroxylamines are oxidized to nitroxide radicals by oxidants, it is thought that the ESR S/Ns can be used as an index for oxidation in leaves.
Effect of Solvents on the Preparation of Silica-Coated Magnetic Particles
Authors: Wang Hongzhi , Nakamura Hiroyuki , Yao Ken , Maeda Hideaki , Abe Eiichi
Published: April 2003

The influence of solvents on magnetic particles aggregation during silica coating by the Stober method has been studied, and a simple method has been developed to produce well-dispersed silica-coated magnetic particles using methanol.
Reaction Propagation over a Ring Electrode during Self-Sustained Current Oscillations in the Fe/H2SO4 System
Authors: Shiomi Yuka , Karantonis Antonis , Nakabayashi Seiichiro
Published: April 2003

Spatio-temporal propagation of a reaction front along a ring electrode was observed during self-sustained iron dissolution current oscillations. The propagation was strongly related to the periodicity of the system, which depended on the cell geometry.
Preferential Bond Activation of sp3 C–H over sp2 C–H in α,β-Unsaturated Carboxylic Acids by Ruthenium Complex
Authors: Kanaya Susumu , Komine Nobuyuki , Hirano Masafumi , Komiya Sanshiro
Published: April 2003

Reactions of Ru(1,5-cod)(1,3,5-cot) (1)/Pme3 [cod = cyclooctadiene, cot = cyclooctatriene] with propenoic acids (CH2=CH(R)COOH) give unsaturated ruthenalactones Ru[OC(O)C(R)=CH-κ2O,C](Pme3)4 [R = Me (2a), Et (2b), Pr (2c), iPr (2d)]. In contrast, reactions of trans-2-methyl-2-butenoic acid and 2-methylcinnamic acid (R′CH=C(Me)COOH) give Ru[OC(O)C(CH2R′)=CH-κ2O,C](Pme3)4 [R′ = Me (2b), Ph (2e)] as major products, suggesting the preferential activation of the sp3 C–H over sp2 C–H bond on ruthenium(II) center.
Development of a Two-Dimensional Evaluation Method for Thin Layers Using Surface Plasmon Resonance
Authors: Otsuki Soichi , Murai Kensuke , Yoshikawa Susumu
Published: April 2003

A two-dimensional evaluation method for intermolecular interactions based on surface plasmon resonance (SPR) was developed. The measurement was conducted at varying wavelengths. The wavelength affording the minimum brightness (SPR wavelength) was determined at each pixels of the image. The spatial distribution of SPR wavelength was converted to a thickness distribution in nm scale, which well presented structures of thin materials attached on silver film.
Hydrogen Generation from Water with Nonthermal Plasma
Authors: Kabashima Hajime , Einaga Hisahiro , Futamura Shigeru
Published: April 2003

Nonthermal plasma chemical decomposition of water was carried out with two different types of reactors such as ferroelectric packed-bed (FPR) and silent discharge (SDR) to explore the possibility of hydrogen generation in a flow reaction system. When FPR was used, the H2 yield in this reaction reached 63% at 150 kJ L−1 of supplied specific energy density in N2. On the other hand, the H2 yield was much lower with SDR than with FPR under the same conditions.
Homo-Coupling Polycondensation of Bis(alkynylsilane)s Mediated by Copper(I) Chloride: A New Synthesis of Poly(arylenebutadiynylene)s
Authors: Nishihara Yasushi , Kato Tsuyoshi , Ando Jun-ichi , Mori Atsunori , Hiyama Tamejiro
Published: April 2003

Homo-coupling polycondensation of aromatic compounds bearing two (trimethylsilyl)ethynyl groups mediated by copper(I) chloride in DMF gives conjugated poly(arylenebutadiynylene)s in up to 94% yield with molecular weight of 4000–8900 (Mw/Mn = 1.78–2.09).
Methyl Sulfonium Salts of 9,9′-Bibenzonorbornenylidene Episulfides: Preparation and Isomerization
Authors: Sugihara Yoshiaki , Aoyama Yui , Nakayama Juzo
Published: April 2003

Methylations of bibenzonorbornenylidene episulfides 5 and 6 by Me3O+BF4− at −18 °C furnished the corresponding episulfonium salts 7 and 8, respectively, with retention of the configuration of the episulfides, whereas those at room temperature or above produced a mixture of 7 and 8 in the ratio of about 1:4. Dynamic 1H NMR investigation in the temperature range 25–40 °C allowed the determination of the activation parameters of the isomerization between 7 and 8, which obeyed first-order kinetics.
Synthesis and Redox Property of Cyclic Mixed-Metal Complexes from Diethynylbiferrocene
Authors: Mori Yukie , Kasai Takeshi , Takesada Toru , Komatsu Hiroaki , Yamazaki Hiroshi , Haga Masa-aki
Published: April 2003

The reaction of 6,6′-diethynylbiferrocene (1) with cis-PtCl2(PR3) (R= nBu and Me) or (η5-C5H5)Co(PR3)2 gave novel cyclic mixed metal complexes, which show a rich oxidative electrochemistry.
Unprecedented Rhodium-Mediated Tetramerization of Bulky Terminal Alkynes Leading to Hydropentalenylrhodium Complexes
Authors: Komatsu Hiroaki , Suzuki Yasunobu , Yamazaki Hiroshi
Published: April 2003

The reactions of bulky terminal alkynes, RC≡CH [R= tBu, 1a; Me3Si, 1b; (cod)Rh(η5-Me2C5H2), 1c] with [RhCl(cod)]2 in the presence of Et3N have been found to provide novel hydropentalenylrhodium complexes, (cod)Rh(η5-R4C8H3) (2, 4 and 5). The structures have been determined by a single-crystal X-ray diffraction analysis. A mechanism involving the migration of an α-tert-butyl group or an α-hydrogen atom of the metal–vinyl intermediates is proposed.
Sorted circles in the maritime Subantarctic, Marion Island
Authors: Holness Stephen Dale
Published: April 2003

Active sorted circles are quantitatively described for the first time for the maritime Subantarctic. Increasing altitude and hence increasing frost penetration are associated with systematic increases in pattern spacing, cell width, height of the fine centre relative to the border, and depth of sorting (but not the width of coarse margins). These results imply consistent dimensional scaling of circle parameters. It is argued, on the basis of the altitudinal trends in pattern morphology, the dimensional scaling of forms, and the morphology of the patterns, that differential frost heave in association with convection cells is responsible for circle formation. Copyright © 2003 John Wiley & Sons, Ltd.
Processes and rates of sediment and wood accumulation in headwater streams of the Oregon Coast Range, USA
Authors: May Christine L. , Gresswell Robert E.
Published: April 2003

Channels that have been scoured to bedrock by debris flows provide unique opportunities to calculate the rate of sediment and wood accumulation in low‐order streams, to understand the temporal succession of channel morphology following disturbance, and to make inferences about processes associated with input and transport of sediment. Dendrochronology was used to estimate the time since the previous debris flow and the time since the last stand‐replacement fire in unlogged basins in the central Coast Range of Oregon. Debris flow activity increased 42 per cent above the background rate in the decades immediately following the last wildfire. Changes in wood and sediment storage were quantified for 13 streams that ranged from 4 to 144 years since the previous debris flow. The volume of wood and sediment in the channel, and the length of channel with exposed bedrock, were strongly correlated with the time since the previous debris flow. Wood increased the storage capacity of the channel and trapped the majority of the sediment in these steep headwater streams. In the absence of wood, channels that have been scoured to bedrock by a debris flow may lack the capacity to store sediment and could persist in a bedrock state for an extended period of time. With an adequate supply of wood, low‐order channels have the potential of storing large volumes of sediment in the interval between debris flows and can function as one of the dominant storage reservoirs for sediment in mountainous terrain. Copyright © 2003 John Wiley & Sons, Ltd.
On evolution of bed material waves in alluvial rivers
Authors: Cao Zhixian , Carling Paul A.
Published: April 2003

Field and laboratory measurements have shown distinct characteristics of bed sediment waves under differing conditions, whilst their theoretical interpretation has emerged to be equivocal. This note aims to clarify the interpretation of evolution of bed material waves. The complete set of governing equations for the flow–sediment–morphology system is deduced to demonstrate its universally hyperbolic nature, irrespective of the sediment transport functions implemented to close the equations. The hyperbolic nature can admit not only attenuating bed material waves, but also shock‐like waves that are not unusual in the real world. It is suggested that the theory of dispersion/diffusion is not universally appropriate for evolution of bed material waves. Copyright © 2003 John Wiley & Sons, Ltd.
Hydrophilic Films Based on Blends of Poly(acrylic acid) and Poly(2‐hydroxyethyl vinyl ether): Thermal, Mechanical, and Morphological Characterization
Authors: Khutoryanskiy Vitaliy V. , Cascone Maria Grazia , Lazzeri Luigi , Barbani Nicoletta , Nurkeeva Zauresh S. , Mun Grigoriy A. , Bitekenova Asem B. , Dzhusupbekova Aizhana B.
Published: April 2003

Hydrophilic films based on blends of poly(acrylic acid) and poly(2‐hydroxyethyl vinyl ether) were prepared by casting. The characterization of the films was performed by differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), and scanning electron microscopy (SEM). It was shown that an increase of poly(2‐hydroxyethyl vinyl ether) content in the blends considerably decreases the glass transition temperature of the samples. The films containing 10 and 20 mol‐% of poly(2‐hydroxyethyl vinyl ether) show behavior of polymers in the glassy state, but a further increase of nonionic polymer content in the blend (30–50 mol‐%) provides the mechanical properties typical of a rubbery state. The content of water traces in the films has a significant effect on the mechanical properties of the materials.

Normalized DSC thermograms of PAA:PHEVE films. [PAA]:[PHEVE] = 90:10 (1), 80:20 (2), 70:30 (3), 60:40 (4), 50:50 mol‐% (5).

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Normalized DSC thermograms of PAA:PHEVE films. [PAA]:[PHEVE] = 90:10 (1), 80:20 (2), 70:30 (3), 60:40 (4), 50:50 mol‐% (5).
Generalization of Kähler angle and integral geometry in complex projective spaces II
Authors: Tasaki Hiroyuki
Published: April 2003

In a previous paper the author has generalized the Kähler angle to the multiple Kähler angle and formulated a Poincaré formula for any real submanifolds in complex projective spaces ℂPn using the multiple Kähler angles of the submanifolds. In this paper we formulate a Poincaré formula for submanifolds M and N of complementary dimension in ℂPn by a symmetric polynomial of degree one in cos2 θi and cos2 τj, where θi and τj are the multiple Kähler angles of M and N. We also obtain some inequalities between the integral of the intersection numbers of submanifolds and their volumes in some cases.
Architecture of Polymeric Superstructures Constructed by Mesoscopically Ordered Cubic Lattices
Authors: Ishizu Koji
Published: April 2003

Highly monodisperse crosslinked core‐shell polymer microspheres could be prepared easily by introducing special crosslinking reagents into the segregated core in block copolymer assembly films. The crosslinked core was stabilized sterically by highly branched shell chains in solution. These microspheres moved like pseudo‐latex. The microspheres formed a lattice with a body‐centered cubic (BCC) structure near the overlap threshold (C*). This structure changed to a face‐centered cubic (FCC) lattice in the bulk region of the films. Photofunctionalized core‐shell microspheres were prepared by introducing dithiocarbamate (DC) groups into shell parts by means of polymer reactions, where DC groups could be propagated using vinyl monomers such as methyl methacrylate (MMA) with living radical mechanism. Polymeric superstructure (three microphase‐separated structure) films were constructed by graft copolymerization of MMA initiated with photofunctionalized microspheres such as macroinitiators under UV irradiation, exhibiting self‐coloring due to Bragg diffraction. These materials can be used for the construction of optical devices such as for the fabrication of light modulators.

Photograph of a solution of the microsphere in MMA.

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Photograph of a solution of the microsphere in MMA.
Potentials and Limitations of Automated Parallel Emulsion Polymerization
Authors: Voorn Dirk‐Jan , Fijten Martin W. M. , Meuldijk Jan , Schubert Ulrich S. , van Herk Alex M.
Published: April 2003

The application of automated parallel synthesizer robots for the investigation of polymerization processes is of major interest at present. In this contribution we describe the application of the emulsion polymerization of styrene and vinyl acetate. The preparations of emulsions and latexes were investigated in detail and compared to “conventional” stirred tank reactors. In particular the influence of the vortex mixing as well as the limitations regarding solid content and reactor fouling are addressed.

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Enhancement of Photostability in Blue‐Light‐Emitting Polymers Doped with Gold Nanoparticles
Authors: Park Jong Hyeok , Lim Yong Taik , Park O Ok , Kim Young Chul
Published: April 2003

A dramatic increase in the photostability of a blue‐light‐emitting polymer, poly(9,9‐dioctylfluorene), was achieved by the addition of 5–10 nm gold nanoparticles. The optical absorption band of the gold nanoparticles was tuned to resonate the triplet exciton ground state bandgap energy of the polymer. Photo‐oxidation rate of poly(9,9‐dioctylfluorene) was effectively reduced by doping the polymer with very small amounts (≈10−6–10−5 volume fraction) of the gold nanoparticles.

Retarded photo‐oxidation in PDOF nanocomposite films with various doped gold nanoparticles.

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Retarded photo‐oxidation in PDOF nanocomposite films with various doped gold nanoparticles.
Time–accurate Modular CFD‐CSD Coupling for Aeroelastic Rotor Simulations
Authors: Altmikus A. , Wagner S.
Published: April 2003

This paper addresses the timewise accuracy of different coupling approaches applied to instationary aeroelastic simulations of rotors in forward flight. Two different approaches which are widely discussed in literature are examined: the tight or strong coupling, and the fully integrated or monolithic coupling.

Strong coupling means an exchange of fluid loads and structural deformations at each time step which is effectuated in a fully modular manner. We will address aspects of conservativity and time‐accuracy, and will present results for a helicopter forward flight scenario. However, objections concerning the correct solution of the global non‐linear three field problem – structure, grid deformation, aerodynamics – remain.

These objections are normally rejected by the monolithic approach. Here, a common set of partial differential equations is derived and solved in a single code. However, a truly monolithic system of equations is only needed for stability analysis, and it can be decomposed in a three field problem respecting appropriate boundary conditions for each domain. Thus, modularity can be maintained, conceiving a quasi‐monolithic procedure, when both domains are simultaneously solved in a common non‐linear iteration loop on a per time‐step basis. First results will be shown for a 2D flutter testcase.
Automatic Differentiation for MATLAB Programs
Authors: Bischof Christian , Lang Bruno , Vehreschild Andre
Published: April 2003

Derivative information is required in numerous applications, including sensitivity analysis and numerical optimization. For simple functions, symbolic differentiation–done either manually or with a computer algebra system–can provide the derivatives, whereas divided differences (DD) have been used traditionally for functions defined by (potentially very complex) computer programs, even if only approximate values can be obtained this way. An alternative approach for such functions is automatic differentiation (AD), yielding exact derivatives at often lower cost than DD, and without restrictions on the program complexity. In this paper we compare the functionality and describe the use of ADMIT/ADMAT and ADiMat. These two AD tools provide derivatives for programs written in the MATLAB language, which is widely used for prototype and production software in scientific and engineering applications. While ADMIT/ADMAT implements a pure operator overloading approach of AD, ADiMat also employes source transformation techniques.
A Note on a Nonlinear Model of a Piezoelectric Rod
Authors: Gausmann R. , Seemann W.
Published: April 2003

If piezoceramics are excited by weak electric fields a nonlinear behavior can be observed, if the excitation frequency is close to a resonance frequency of the system. To derive a theoretical model nonlinear constitutive equations are used, to describe the longitudinal oscillations of a slender piezoceramic rod near the first resonance frequency. Hamilton's principle is used to receive a variational principle for the piezoelectric rod. Introducing a Rayleigh Ritz ansatz with the eigenfunctions of the linearized system to approximate the exact solution leads to nonlinear ordinary differential equations. These equations are approximated with the method of harmonic balance. Finally it is possible to calculate the amplitudes of the displacements numerically. As a result it is shown, that the Duffing type nonlinearities found in measurements can be described with this model.
One‐parametric families of canard cycles: two explicitly solvable examples
Authors: Schneider Klaus R. , Shchetinina Ekaterina V.
Published: April 2003

Systems of singularly perturbed autonomous ordinary differential equations possessing in a parameter plane two intersecting bifurcation curves connected with the generation of limit cycles with large and small amplitude respectively, have a special class of limit cycles called canards or french ducks describing an exponentially fast transition from a small amplitude limit cycle to limit cycle with a large amplitude. We present two explicitly integrable examples of non‐autonomous singularly perturbed di.erential equations with canard cycles without a second parameter.
Stabilitätsanalysen für schwingende Seile
Authors: Thalheim J.‐U. , Heinen A. H.
Published: April 2003

Bei Seilkonstruktionen (z.B. abgespannte Maste, Schrägseilbrücken) sind einige unerwartete Schwingungs‐ und Instabilitätsphänomene aufgetreten, wie z.B. Regen/Wind‐induzierte und parametererregte Schwingungen, siehe [1] und Bild 3. Ausgehend von den nichtlinearen Seilgleichungen werden diese mittels des Prinzips der virtuellen Verrückungen (PdV) in eine FE‐Formulierung überführt, aus der auf der Basis des Ljapunowschen Kriteriums kinetische Stabilitätsgleichungen gewonnen werden, die auf ein Seil unter hamonischer Auflagerbewegung angewendet werden, da so z.B. die Wirkung von Pylonbewegungen auf die Seile von Schrägseilbrücken abgeschätzt werden kann.
Ein Zeitschrittverfahren für mechanische Schwingungssysteme mit fraktionalen Ableitungen
Authors: Wagner Nils
Published: April 2003

Systeme mit nachlassendem Gedächtnis werden sowohl mit dem Konzept Innerer Variablen als auch mit dem der fraktionalen Ableitungen beschrieben. Startpunkt ist hier die Liouville‐Riemann Definition der fraktionalen Ableitung. Auf der Basis quadratischer Ansatzfunktionen für das Verschiebungs‐ und Geschwindigkeitsfeld wird ein Zeitschrittverfahren entwickelt.
Nichtholonome Bindungen und Systeme
Authors: Braun Manfred
Published: April 2003

Ein mechanisches System, das einer nochtholonomen kinematischen Bindung unterliegt, kann dennoch als ganzes holonom sein. Dies wird am Beispiel eines ebenen Verfolgerproblems demonstriert. Die Verfolgerbedingung ist zwar nichtholonom, sie wird aber durch eine weitere kinematische Bedingung ergänzt, die beispielsweise das Verhältnis der Geschwindigkeiten von Ziel und Verfolger festlegt. Die Verfolgerbedingung kann dann durch eine holonome Linearkombination der beiden kinematischen Bindungen ersetzt werden. Das Gesamtproblem ist also holonom, obwohl in der ursprünglichen Formulierung eine der beiden kinematischen Bindungen nichtholonom war.
Dynamic Aspects in Satellite Capturing by Robotic Manipulator
Authors: Rebele B. , Schäfer B. , Lopez‐Doriga D. B.
Published: April 2003

Since several years the interest in offering satellite services for maintenance and repair of malfunctioned satellites is strongly increasing. Currently, a very typical and actual application is dedicated to the rescue of a defect satellite (Rosat) in low earth orbit by means of a servicer satellite based manipulator [1]. The dynamic aspects are carefully considered in order to minimize both, the strong vibrational behavior of the combined satellite system, and the mechanical stresses in the slender boom and the robotic joints and arm structure, and consequently, to find the optimal capturing strategy.
Elastic–plastic buckling of annular circular plate with linear material hardening
Authors: Bremec B. , Kosel F. , Petrišič J.
Published: April 2003

The contribution treats the buckling problem of a circular annular plate where the unstable state and the buckling process occurs when the stress state in the most loaded points of the plate is already in the elastic–plastic region. It is supposed that the plate buckles axisymmetrically (m = 0) or nonaxisymmetrically with m > 0, m ∈ ℕ waves in the circumferential direction. Using the equilibrium method, the critical buckling loads are calculated. The results show the influence of the material hardening coefficient 0 ≤ f ≤ 1 on the buckling load. The comparison between calculations with the consideration of flow and deformation theory of plasticity is given.
Stress and deformation states in the annulus made from shape memory material
Authors: Kosel F. , Videnic T.
Published: April 2003

The contribution deals with the stress and deformation states in an annulus made of shape memory material (SMM). The loading‐unloading process is going on at constant temperature, which is below temperature Mf (martensite finish temperature). The research is focused on the determination of the stress and deformation states in the annulus after loading and unloading process. These results are necessary for treating process of constrained recovery in shape memory annulus. The real loading‐unloading function in the stress‐strain coordinate system of shape memory material (Ni–Ti–Cu) is included in the mathematical model.
Randelementmethoden zur elektromechanischen Festigkeitsanalyse piezoelektrischer Strukturen
Authors: Groh U.
Published: April 2003

Zur Untersuchung der Zuverlässigkeit piezokeramischer Konstruktionselemente bei mechanisch‐elektrischer Belastung werden u.a. Intensitätsfaktoren herangezogen, die die Singularität der Felder des elektro‐elastischen Problems an Rissspitzen charakterisieren. Für die Lösung der entsprechenden zweidimensionalen Randwertaufgabe wurde ein bezüglich Geometrie, Material und Randbedingungen flexibles Kollokations‐Randelementverfahren entwickelt, das Singularitäten an Rissspitzen mit singulären Randelementen erfasst. Bereits mit wenigen Randelementen ist eine relativ hohe Genauigkeit der berechneten Intensitätsfaktoren erzielbar.
A Shortcoming in the Geometrically Non‐Linear Shakedown Theorem
Authors: Schieck B.
Published: April 2003

The original static shakedown theorem of Melan [1], valid for geometrically linear theory, was extended for geometrically non‐linear theory e.g. by Polizzotto and Borino [2], who presented a proof for large rotations with small strains. However, a counterexample to this extended Melan's theorem has been found. The reason of the failure is investigated and is corrected by an additional condition in the theorem. The outline of the proof is given.
Incremental Variational Principles in Damage Mechanics
Authors: Schmidt‐Baldassari Martin , Hackl Klaus
Published: April 2003

We propose a new kind of damage formulation which leads, in connection with relaxation techniques known in literature, to a well posed problem suitable for finite element calculations. The model is rate‐dependent and allows a consistent treatment of micro‐structures and localization phenomena.
Finite Element Modelling of Cracks Based on the Partition of Unity Method
Authors: Dumstorff P. , Meschke G.
Published: April 2003

In this paper a finite element model for the analysis of brittle materials in the post cracking regime is presented. The model allows the representation of failure zones several times smaller than the structure itself using relatively coarse finite element meshes. The formulation is based on the partition of unity method. Discontinuous shape functions are used to enrich the continuous approximation of the displacement field where a crack has opened [2]. The magnitude of the displacement jump is determined by extra degrees of freedom at existing nodes. The crack path is completely independent of the structure of the mesh and is continuous across element boundaries. To model inelastic deformations around the crack tip a cohesive crack model is used. A representative numerical example illustrates the performance of the proposed model.
Simulation of bone modeling around a screw implant in the mandible
Authors: Rong Q. , Lenz J. , Schweizerhof K. , Schindler H.J. , Riediger D.
Published: April 2003

On the basis of a biomechanical model for the bone healing process around a dental implant, the attainable degree of ossification in two‐phase implantation is studied for a screw implant and compared with corresponding results for a cylinder implant. It is shown that a screw implant delivers a better ossification of the repair zone than a cylinder implant which is in accordance with clinical observation.
Experimentelle Ermittlung einer vibroakustischen Zielfunktion für die aktiveRegelung von Plattenstrukturen
Authors: Vogl Bernd
Published: April 2003

Für die Entwicklung aktiver Struktursysteme, die u.a. auf die akustische Verbesserung von Bauteilen abzielen, ist die Kenntnis des Zusammenhangs zwischen dem dynamischen Verhalten und dem dadurch induzierten Luftschallfeld notwendig. In einer vorangegangenen Arbeit [1] wurde die theoretische Ermittlung einer vibroakustischen Zielfunktion analytisch am Beispiel einer allseitig gelenkig gelagerten Rechteckplatte gezeigt. Die Übertragung der gewonnenen Erkenntnisse auf ein Experiment mit einer fest eingespannten Rechteckplatte soll hier vorgestellt werden. Über eine Experimentelle Modalanalyse (EMA) lässt sich die Volumenverschiebung, die zur abgestrahlten Schallleistung unterhalb der Koinzidenzfrequenz korreliert [2], diskretisiert als Zielfunktion ermitteln. Die Rekonstruktion dieser Zielfunktion mittels geometrisch äquidistant verteilter, strukturapplizierter piezokeramischer Sensoren (PZT‐Patches) ist das Ziel der Untersuchung. Die Güte der Rekonstruktion wird in dieser Arbeit ebenfalls diskutiert. Die Integration der rekonstruierten Zielfunktion in einen aktiven Regelkreis ist ein weiterführendes Ziel dieser Arbeit.
A nondestructive experimental approach for heat flux determination on direct‐chill cast aluminium alloy billet surface
Authors: Založnik M. , Šarler B. , Bajsić I.
Published: April 2003

In this paper a new nondestructive experimental method for the determination of the billet surface heat flux in direct‐chill casting of aluminium alloys is presented. The new measurement method is based on measurements of the water film temperatures along the billet surface and determination of the local heat flux from the energy balance. Experiments using the new technique are carried out in a real plant environment. The results are used for the validation of a computational model of the process.
Comparison of the Solution of the Riemann Problem for Inviscid/Viscous Flows
Authors: Dykas S. , Goodheart K.A. , Schnerr G.H.
Published: April 2003

The aim of this paper is to present the influence of the method used to solve the convective fluxes on the transonic internal flow field. The governing equations are discretized using an upwind method based on different solutions of the Riemann problem, flux vector splitting (FVS) or flux difference splitting schemes (FDS). Turbulence effects are simulated by means of the low‐Reynolds‐number k – ϵ and the SST (Shear‐Stress‐Transport) turbulence models.
Drag on a fibre in a counterflow air stream
Authors: Redmond Brendan , Harding John
Published: April 2003

This paper evaluates the drag on the surface of a fibre moving axially in a counterflow air stream. It is assumed that the fibre velocity is very much greater than the velocity of the air stream.