bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydrogen Adsorption in Carbon Nanostructures: Comparison of Nanotubes, Fibers, and Coals
Authors: Schimmel H. Gijs , Kearley Gordon J. , Nijkamp Marije G. , Visser Cornelis T. , de Jong Krijn P. , Mulder Fokko M.
Published: October 2003

Single‐walled carbon nanotubes (SWNT) were reported to have record high hydrogen storage capacities at room temperature, indicating an interaction between hydrogen and carbon matrix that is stronger than known before. Here we present a study of the interaction of hydrogen with activated charcoal, carbon nanofibers, and SWNT that disproves these earlier reports. The hydrogen storage capacity of these materials correlates with the surface area of the material, the activated charcoal having the largest. The SWNT appear to have a relatively low accessible surface area due to bundling of the tubes; the hydrogen does not enter the voids between the tubes in the bundles. Pressure–temperature curves were used to estimate the interaction potential, which was found to be 580±60 K. Hydrogen gas was adsorbed in amounts up to 2 wt % only at low temperatures. Molecular rotations observed with neutron scattering indicate that molecular hydrogen is present, and no significant difference was found between the hydrogen molecules adsorbed in the different investigated materials. Results from density functional calculations show molecular hydrogen bonding to an aromatic CC bond that is present in the materials investigated. The claims of high storage capacities of SWNT related to their characteristic morphology are unjustified.
Computational Assessment of the Electronic Structure of 1‐Azacyclohexa‐2,3,5‐triene (3δ2‐1H‐Pyridine) and Its Benzo Derivative (3δ2‐1H‐Quinoline) as well as Generation and Interception of 1‐Methyl‐3δ2‐1H‐quinoline
Authors: Schöneboom Jan C. , Groetsch Stefan , Christl Manfred , Engels Bernd
Published: October 2003

Treatment of a solution of 3‐bromo‐1‐methyl‐1,2‐dihydroquinoline (9) and [18]crown‐6 in furan or styrene with KOtBu followed by hydrolysis afforded a mixture of 1‐methyl‐1,2‐dihydroquinoline (10) and 1‐methyl‐2‐quinolone (11). If the reaction was performed in [D8]THF and the mixture was immediately analysed by NMR spectroscopy, 2‐tert‐butoxy‐1‐methyl‐1,2‐dihydroquinoline (17) was shown to be the precursor of 10 and 11. The structure of 17 is evidence for the title cycloallene 7, which arises from 9 by β elimination of hydrogen bromide and is trapped by KOtBu to give 17 so fast that cycloadditions of 7 with furan or styrene cannot compete. Since this reactivity is unusual compared to the large majority of the known six‐membered cyclic allenes, we performed quantum‐chemical calculations on 8, which is the parent compound of 7, and the corresponding isopyridine 6 to assess the electronic nature of these species. The ground state of 6 was no longer an allene (6 a) but the zwitterion 6 b. In the case of 8, the allene structure 8 a is more stable than the zwitterionic form 8 b by only ≈1 kcal mol−1. These results suggest a high reactivity of 6 and 8 towards nucleophiles and explains the behaviour of 7. In addition to the ground states, the low‐lying excited states of 6 and 8 were considered, which are represented by the diradicals 6 c and 8 c and, as singlets, lie above 6 b and 8 a by 19.1–24.8 and 14.4–17.7 kcal mol−1, respectively.
Unusual Iron(III) Ate Complexes Stabilized By Li–π Interactions
Authors: Mund Garry , Vidovic Dragoslav , Batchelor Raymond J. , Britten James F. , Sharma Rajendra D. , Jones Colin H. W. , Leznoff Daniel B.
Published: October 2003

Several iron(III) complexes incorporating diamidoether ligands are described. The reaction between {Li2[RN(SiMe2)]2O} and FeX3 (X=Cl or Br; R=2,4,6‐Me3Ph or 2,6‐iPr2Ph) form unusual ate complexes, {FeX2Li[RN(SiMe2)]2O}2 (2, X=Cl, R=2,4,6‐Me3Ph; 3, X=Br, R=2,4,6‐Me3Ph; 4, X=Cl, R=2,6‐iPr2Ph) which are stabilized by Li–π interactions. These dimeric iron(III)–diamido complexes exhibit magnetic behaviour characteristic of uncoupled high spin (S= 5/2 ) iron(III) centres. They also undergo halide metathesis resulting in reduced iron(II) species. Thus, reaction of 2 with alkyllithium reagents leads to the formation of iron(II) dimer {Fe[Me3PhN(SiMe2)]2O}2 (6). Similarly, the previously reported iron(III)–diamido complex {FeCl[tBuN(SiMe2)]2O}2 (1) reacts with LiPPh2 to yield the iron(II) dimer {Fe[tBuN(SiMe2)]2O}2 but reaction with LiNPh2 gives the iron(II) product {Fe2(NPh2)2[tBuN(SiMe2)]2O} (5). Some redox chemistry is also observed as side reactions in the syntheses of 2–4, yielding THF adducts of FeX2: the one‐dimensional chain [FeBr2(THF)2]n (7) and the cluster [Fe4Cl8(THF)6]. The X‐ray crystal structures of 3, 5 and 7 are described.
Quality of service control in multimedia network clusters
Authors: Davoli Franco , Maryni Piergiulio
Published: October 2003

We introduce a control architecture in which several (independent) multimedia clusters share the same (local or metropolitan) networking resources in a controlled framework. In particular, a central entity (i.e., the Gatekeeper) harmonizes the transmission rates of the various clusters following a given sharing policy. Each cluster, in turn, adopts its own end‐to‐end rate control mechanism to meet the Gatekeeper's transmission rate indications. A testbed has been developed and the system has been evaluated with real experiments by using different types of transmission sources. A software architecture is also introduced and described, with particular reference to the middleware framework realized with the Jini system. Copyright © 2003 John Wiley & Sons, Ltd.
Modulation of the Communication between Redox Centers in a Tris(ferrocene)‐tren Ligand by Complexation of Lanthanide Ions
Authors: Heitzmann Marie , Moutet Jean‐Claude , Pécaut Jacques , Reynes Olivier , Royal Guy , Saint‐Aman Eric , Serratrice Guy
Published: October 2003

The tripodal ligand L built on the tren platform and bearing three chemically equivalent ferrocene units was prepared and characterized. Electrochemical investigations indicate that electrostatic communication occurs between the three ferrocene groups in L, which leads to the observation of two distinct voltammetric waves. The electrochemical communication between the three ferrocene moieties is disrupted in 1:1 (L:M3+) type complexes formed between L and Y3+ or Eu3+ metal cations and their electrochemical response tends towards that of a single three‐independent‐electrons oxidation wave. Modulation of the electrochemical properties of L in the presence of lanthanide ions might be exploited with a view to their electrochemical sensing in organic and aqueous media. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Syntheses, Structures, and Properties of Two‐Dimensional Honeycomb Networks from the Assembly of the Tripodal Ligand 2,4,6‐Tris[4‐(imidazol‐1‐ylmethyl)phenyl]‐1,3,5‐triazine with Metal Salts
Authors: Wan Shuang‐Yi , Li Yi‐Zhi , Okamura Taka‐aki , Fan Jian , Sun Wei‐Yin , Ueyama Norikazu
Published: October 2003

Two novel coordination networks, [Zn2(timpt)2(μ‐OH)](NO3)3 (1) and [Ni2(timpt)2(H2O)2(SO4)2]·0.5H2O (2) were obtained by assembly of 2,4,6‐tris[4‐(imidazol‐1‐ylmethyl)phenyl]‐1,3,5‐triazine (timpt) with the corresponding metal salts. The X‐ray single‐crystal diffraction analysis reveals that complex 1 possesses μ‐OH‐bridged dinuclear zinc(II) subunits (Zn2OH) and each timpt ligand connects three metal atoms to form a two‐dimensional (2D) honeycomb network structure, in which each independent sheet contains two sublayers. While in the case of complex 2, the nickel(II) atom is coordinated by N atoms of timpt, O atoms of sulfate anions and water molecules to give a 2D honeycomb network. The luminescence properties of timpt, 1 and 2 in the solid state were investigated at room temperature. The maximum emission wavelength of 1 is red‐shifted by 17 nm compared with that of timpt. While complex 2 showed an emission with remarkably reduced intensity under the same conditions. The results imply that the metal ions have great influence on the structure and properties of the complexes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Adolescent psychotherapy: An introduction
Authors: Rubenstein Alice K.
Published: October 2003

Adolescent psychotherapy has only recently taken hold as distinct from either child or adult psychotherapy. This new recognition was born of necessity as practitioners saw that theories and techniques developed for treating children and adults were far less effective for treating adolescents. As necessity is often the mother of invention, new models for treating adolescents have emerged. While these models differ in many respects, they share three characteristics: the unique features of adolescents, psychotherapists requiring specialized knowledge and skills, and the need for adolescent psychotherapy to involve the broader systemic context of the adolescent's life. The articles in this issue ofIn Session: Journal of Clinical Psychologyinsist that practitioners recognize and challenge their assumptions about how psychotherapy with adolescents should be conducted. The articles highlight the need for specialized training, the scarcity of evidenced‐based research, and the ethical dilemmas that frequently occur when working with this population. © 2003 Wiley Periodicals, Inc. J Clin Psychol/In Session.
On treating adolescent girls: Focus on strengths and resiliency in psychotherapy
Authors: Johnson Norine G.
Published: October 2003

This strength‐based psychotherapy with adolescent girls and their families is derived from feminist psychology, positive psychology, and strength‐based interventions with teens. Research reviewed by the American Psychological Association's Presidential Task Force on Adolescent Girls formed the basis of specific interventions within this approach. Research findings that contributed are the effects on teen girls of positive parental relationships; utilizing strengths of their race, ethnicity, class, and gender; positive body images; being outspoken in relationships; problem‐solving skills that foster independence; and family support for independence. The strength‐based approach is illustrated by a case example of a 13‐year‐old European American girl with acting‐out behaviors, depression, and subclinical attention‐deficit/hyperactivity disorder. The case illustrates how to empower adolescent girls within therapy, when and how to include parents, how to change the focus to strengths, and how to help the parents assess and build upon their daughters' strengths. © 2003 Wiley Periodicals, Inc. J Clin Psychol/In Session.
Relational psychoanalytic treatment for young adult males
Authors: Pollack William S.
Published: October 2003

The clinical treatment of an adolescent young adult male is presented to both illustrate and operationalize the author's hypothesis that a new model of relational psychoanalytic treatment is likely to have beneficial effects, particularly among this population. The contention that males as young boys undergo a normative trauma of premature separation in our society, which is likely to give rise to underdiagnosed abandonment depressive syndromes in teenage boys, is argued. It is represented that psychotherapists attempting to diagnose and treat a wide rage of disorders in young males would do well to rethink their approach from this new perspective. © 2003 Wiley Periodicals, Inc. J Clin Psychol/In Session.
Control of endothelial cell proliferation by calcium influx and arachidonic acid metabolism: A pharmacological approach
Authors: Antoniotti Susanna , Fiorio Pla Alessandra , Pregnolato Sandra , Mottola Annalisa , Lovisolo Davide , Munaron Luca
Published: October 2003

In physiological conditions, endothelial cell proliferation is strictly controlled by several growth factors, among which bFGF and VEGF are the most effective. Both bind to specific tyrosine kinase receptors and trigger intracellular signal cascades. In particular, bFGF stimulates the release of arachidonic acid (AA) and its metabolites in many types of endothelial cells in culture. In bovine aortic endothelial cells, it has been suggested that AA is released by the recruitment of cytosolic phospholipase A2 (cPLA2). AA metabolites are involved in the control of both endothelial cell motility (mostly via the cyclooxygenase pathway) and proliferation (via the lipoxygenase (LOX) cascade). On the other hand, evidence has been provided for a proliferative role of AA‐induced calcium influx. By using a pharmacological approach, we have tried to elucidate the contribution to bovine aortic endothelial proliferation of the different pathways leading to production of AA and its metabolites. Two main informations were obtained by our experiments: first, AA release is not entirely due to cPLA2 involvement, but also to DAG lipase recruitment; second, cyclooxygenase derivatives play a role in the control of cell proliferation, and not only of motility. Moreover, by combining proliferation assays and single cell calcium measurements, we show that the blocking effect of carboxyamido‐triazole (CAI), an inhibitor of tumor growth and angiogenesis acting on calcium influx‐dependent pathways, including AA metabolism, is at least in part due to a direct effect on AA‐induced calcium influx. J. Cell. Physiol. 197: 370–378, 2003© 2003 Wiley‐Liss, Inc.
TNFα suppresses link protein and type II collagen expression in chondrocytes: Role of MEK1/2 and NF‐κB signaling pathways
Authors: Séguin Cheryle A. , Bernier Suzanne M.
Published: October 2003

Tumor necrosis factor α (TNFα) inhibits matrix synthesis by chondrocytes in rheumatoid arthritis and osteoarthritis; however, the underlying signaling pathways are poorly characterized. This study investigated the TNFα‐activated pathways regulating expression of two key components of the cartilage matrix—link protein and type II collagen. In rat articular chondrocytes, TNFα decreased link protein and type II collagen mRNA to undetectable levels within 48 h. Levels of link protein mRNA recovered more readily than type II collagen mRNA following removal of the cytokine. TNFα‐mediated reduction in mRNA of both matrix molecules occurred at the level of transcription and, for link protein, mRNA stability. Turnover of type II collagen and link protein mRNA was dependent on new protein synthesis. In both prechondrocytes and articular chondrocytes, TNFα induced concentration‐dependent activation of MEK1/2 and NF‐κB, but not p38 or JNK. Sustained activation of NF‐κB was observed for up to 72 h following continuous or transient exposure to TNFα. Using pharmacological and molecular approaches, the MEK1/2 and NF‐κB pathways were found to mediate inhibition of type II collagen and link protein gene expression by TNFα. Both prechondrocytes and articular chondrocytes are targets of TNFα. This study identifies pathways through which TNFα perturbs the synthesis and organization of articular cartilage matrix during inflammation. J. Cell. Physiol. 197: 357–369, 2003© 2003 Wiley‐Liss, Inc.
Role of nitric oxide, reactive oxygen species, and p38 MAP kinase in the regulation of human chondrocyte apoptosis
Authors: Kühn Klaus , Shikhman Alexander R. , Lotz Martin
Published: October 2003

This study addresses mechanisms by which interleukin‐1β (IL‐1β) regulates human chondrocyte apoptosis induced by a combination of the anti‐CD95 antibody CH‐11 and the proteasome inhibitor (PSI). The effect of IL‐1β on apoptosis varied among tissue samples. IL‐1β either enhanced (16/22 samples) or inhibited (6/22 samples) DNA fragmentation and caspase‐3 processing. The protective effect of IL‐1β was abrogated by the nitric oxide (NO) synthesis inhibitor N‐monomethyl‐l‐arginine (L‐NMMA) while apoptosis stimulation was not affected. The NO‐donors sodium nitroprusside (SNP) and S‐nitroso‐N‐acetyl penicillamine (SNAP) blocked DNA fragmentation, and this was associated with partial inhibition of caspase‐3 processing. Pyrrolidine dithiocarbamate (PDTC), a scavenger of reactive oxygen species (ROS) blocked apoptosis induction by CH‐11/PSI as well as the enhancement by IL‐1β. The pro‐apoptotic effects of IL‐1β were also abrogated by the p38 inhibitor SB 202190. In conclusion, IL‐1β augments CH‐11/PSI induced apoptosis in the majority of chondrocyte samples. The pro‐apoptotic effect of IL‐1β is not dependent on NO. In contrast, the anti‐apoptotic effect of IL‐1β observed in a minority of samples is partially NO‐dependent. J. Cell. Physiol. 197: 379–387, 2003© 2003 Wiley‐Liss, Inc.
Modulation of vascular smooth muscle cell growth by magnesium—role of mitogen—activated protein kinases
Authors: Touyz Rhian M. , Yao Guoying
Published: October 2003

We tested the hypothesis that Mg2+ influences growth of vascular smooth muscle cells (VSMCs) by modulating cell cycle activation through mitogen‐activated protein (MAP) kinase‐dependent pathways. Rat VSMCs were grown in culture medium containing normal Mg2+ (1.02 mmol/L, control) and increasing concentrations of Mg2+ (2–4 mmol/L) for 1–8 days. Effects of varying extracellular Mg2+ concentration ([Mg2+]e) on intracellular free Mg2+ concentration ([Mg2+]i) were assessed using mag‐fura. Growth actions of Mg2+ were evaluated by measuring cell cycle activation, DNA synthesis, and protein synthesis. Expression of cell cycle promoters, cyclin D1, cyclin E, Cdk2, and Cdk4 was assessed by immunoblotting. Phosphorylation of cell cycle inhibitors p21cip1 and p27kip1 and MAP kinases, ERK1/2, p38MAP kinase, and JNK was evaluated using phospho‐specific antibodies. [Mg2+]i increased in a dose‐dependent manner in response to increasing [Mg2+]e. These effects were evident within 2 days and maximal responses were obtained after 6 days. High [Mg2+]e induced cell cycle activation with a lower proportion of cells in G1 phase (75 ± 1.0%) and a higher fraction of cells in S phase (12 ± 0.7%) versus control (G1, 88.5 ± 1.4%; S, 6.8 ± 1.2%; P < 0.05). This was associated with increased protein content of cyclin D1 and Cdk4 and decreased activation of p21cip1 and p27kip1. In cells exposed to 2 mmol/L Mg2+, DNA and protein synthesis was increased ∼threefold. Phosphorylation of MEK1/2 and ERK1/2 was enhanced two to threefold in cells grown in 2 mmol/L Mg2+. These effects were rapid, occurring within 2 days. Phosphorylation of MEK3/6, p38 MAP kinase, and JNK was unaltered by increasing [Mg2]e. PD98059 (10−5 mol/L), specific MEK1/2 inhibitor, but not SB202190 (10−5 mol/L) (specific p38 MAP kinase inhibitor), attenuated Mg2+‐induced growth actions. These data demonstrate the novel findings that cell cycle activation and growth regulation by Mg2+ occurs via ERK1/2‐dependent, p38 MAP kinase‐independent pathways. J. Cell. Physiol. 197: 326–335, 2003© 2003 Wiley‐Liss, Inc.
Raman spectroscopy of some natural hydrotalcites with sulphate and carbonate in the interlayer
Authors: Frost Ray L. , Weier Matt L. , Kloprogge J. Theo
Published: October 2003

The structures of a series of nickel‐ and magnesium‐based hydrotalcites were explored using Raman microscopy. These natural hydrotalcites are based upon sulphate or carbonate being the counter anion in the interlayer. Variation in the position of the sulphate stretching vibrations occurs and is mineral dependent. Raman spectroscopy shows a reduction in the symmetry of both sulphate and carbonate, which leads to the conclusion that the anions are bonded to the brucite‐like hydroxyl surface and to the water in the interlayer. Water bending modes are identified in both the Raman and infrared spectra at positions greater than 1630 cm−1, indicating that the water is strongly hydrogen bonded to both the interlayer anions and the hydrotalcite surface. Copyright © 2003 John Wiley & Sons, Ltd.
Infrared and Raman spectral studies of L‐ornithine nitrate
Authors: Ramaswamy S. , Umadevi M. , Rajaram R. K. , Ramakrishnan V.
Published: October 2003

FT‐IR and FT‐Raman spectra of L‐ornithine nitrate were recorded and analyzed. The assignments of the fundamental vibrational modes due to COO−, NH3+, CH2, CH, CN and NO3− groups were made. The carboxylic group is found to exist as the COO− ion in the crystal. The formation of N–HO hydrogen bonds in the crystal contributes considerably to the crystal cohesion. The wavenumbers of several modes of vibrations were shifted from the expected values, indicating extensive intermolecular hydrogen bonding. Some of the forbidden modes of the nitrate group have been observed. The removal of degeneracy of the nitrate anion suggests that the symmetry of the nitrate group has been affected in the crystalline environment. Copyright © 2003 John Wiley & Sons, Ltd.
Kinetic and Mechanistic Studies of Carboxylic Acid–Bisoxazoline Chain‐Coupling Reactions
Authors: Néry Laurent , Lefebvre Hervé , Fradet Alain
Published: October 2003

Kinetic studies of the reactions between a model carboxylic acid and bisoxazoline coupling agents, namely 2,2′‐(1,3‐phenylene)bis(2‐oxazoline) (mbox), 2,2′‐(1,4‐phenylene)bis(2‐oxazoline) (pbox), and 2,2′‐(2,6‐pyridylene)bis(2‐oxazoline) (pybox), were carried out in bulk at 140–220 °C. A second‐order two‐step reaction mechanism was proposed and was verified by the experimental results. The results also indicate that the reactivity of the oxazoline groups is unchanged after the reaction of the other oxazoline group of the same coupling agent moiety, that is, oxazoline groups are equireactive. Rate constants and activation enthalpies and entropies were determined, allowing the comparison of bisoxazoline reactivity. The following reactivity order was found: pybox > mbox > pbox. The formation of a stabilized protonated complex is postulated to explain the much higher reaction rate observed with the new coupling agent pybox.

Variation of the experimental concentrations of reactants and reaction products versus time.

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Variation of the experimental concentrations of reactants and reaction products versus time.
Potential of light trapping in microcrystalline silicon solar cells with textured substrates
Authors: Krč J. , Smole F. , Topič M.
Published: October 2003

The real and potential benefits of light trapping in microcrystalline silicon single‐junction solar cells are studied theoretically. Effects of a hypothetical high haze parameter of textured transparent conductive oxide on quantum efficiency and short‐circuit current of the solar cell are analysed by numerical simulation. The role of the angular distribution function of scattered light as a second important scattering parameter is shown. The potential thickness reductions of the intrinsic layer due to enhanced light trapping are demonstrated. Copyright © 2003 John Wiley & Sons, Ltd.
Quantifying epidemiologic risk factors using non‐parametric regression: model selection remains the greatest challenge
Authors: Rosenberg Philip S. , Katki Hormuzd , Swanson Christine A. , Brown Linda M. , Wacholder Sholom , Hoover Robert N.
Published: October 2003

Logistic regression is widely used to estimate relative risks (odds ratios) from case–control studies, but when the study exposure is continuous, standard parametric models may not accurately characterize the exposure–response curve. Semi‐parametric generalized linear models provide a useful extension. In these models, the exposure of interest is modelled flexibly using a regression spline or a smoothing spline, while other variables are modelled using conventional methods. When coupled with a model‐selection procedure based on minimizing a cross‐validation score, this approach provides a non‐parametric, objective, and reproducible method to characterize the exposure–response curve by one or several models with a favourable bias–variance trade‐off. We applied this approach to case–control data to estimate the dose–response relationship between alcohol consumption and risk of oral cancer among African Americans. We did not find a uniquely ‘best’ model, but results using linear, cubic, and smoothing splines were consistent: there does not appear to be a risk‐free threshold for alcohol consumptionvis‐à‐visthe development of oral cancer. This finding was not apparent using a standard step‐function model. In our analysis, the cross‐validation curve had a global minimum and also a local minimum. In general, the phenomenon of multiple local minima makes it more difficult to interpret the results, and may present a computational roadblock to non‐parametric generalized additive models of multiple continuous exposures. Nonetheless, the semi‐parametric approach appears to be a practical advance. Published in 2003 by John Wiley & Sons, Ltd.
What is a ‘phycolichen’? Differences and changes in the meaning of an old lichenological term
Authors: Lange Otto L. , Wagenitz Gerhard
Published: October 2003

The term ‘phycolichens’ has recently been introduced as a synonym for ‘green algal lichens’ i.e. those having phycobionts as their primary autotrophic partner, which is analogous to the contracted term ‘cyanolichen’. However, a study of the history of the term ‘Phycolichenes’ leads us to suggest that this term should not be applied because of considerable ambiguities in past usage and the possibility of confusion. The term was first created by E. Fries in 1831, and was used later by Massalongo as a taxon for homoiomerous cyanobacterial lichens. With this, or similar meanings, it remained in use until the middle of the 20th Century. Diels (A. Engler's Syllabus der Pflanzenfamilien, Gebr. Borntr., Berlin, 1936) defined the same expression Phycolichenes as lichens with Phycomycetes as mycobiont, and this definition can still be found in recent literature. If a shortened term for green algal lichens is needed then we suggest ‘chlorolichens’ as a better counterpart to cyanolichens.
Two phases of Mesozoic north‐south extension in the eastern Altyn Tagh range, northern Tibetan Plateau
Authors: Chen Xuanhua , Yin An , Gehrels George E. , Cowgill Eric S. , Grove Marty , Harrison T. Mark , Wang Xiao‐Feng
Published: October 2003

The >300‐km long, east striking Lapeiquan fault lies in the eastern Altyn Tagh range along the northern margin of the Tibetan Plateau and was interpreted as a north dipping thrust in early studies. However, our mapping shows that the fault is a south dipping normal fault juxtaposing Archean‐Proterozoic gneisses beneath an early Paleozoic volcanic and sedimentary sequence. Its dip angle varies from <30° to ∼60°. The central fault segment is expressed as a 30–50 m thick ductile shear zone with well‐developed mylonitic fabrics and stretching mineral lineations, where the eastern and western segments are characterized by cataclastic deformation. Kinematic indicators such as asymmetric boudinage, asymmetric folds, and minor brittle and ductile faults within the fault zone consistently indicate a top‐south normal‐slip sense of shear. The age of the Lapeiquan fault is constrained by two types of information. First, a sequence of Early‐Middle Jurassic sediments is locally present in the hanging wall of the Lapeiquan fault. The clasts of the Jurassic strata, particularly the stromatolite‐bearing, cherty limestone and purple quartzite, can be correlated uniquely with those in the footwall of the fault. We interpret that the Early‐Middle Jurassic strata were deposited in an extensional basin related to motion along the Lapeiquan fault. Second, 40Ar/39Ar thermochronologic analyses indicate two prominent cooling events in the Lapeiquan footwall. The older event occurred in the latest Triassic‐earliest Jurassic between ∼220 and 187 Ma, while the younger event occurred in the latest Early Cretaceous at ∼100 Ma. Because the 220–187 Ma cooling ages are widespread in the Lapeiquan footwall, we suggest it to represent the main stage of faulting. We interpreted the younger phase of fault motion at ∼100 Ma to have been related to fault reactivation. The deformation was aided by motion along the south dipping Qiashikan normal fault that merges with the eastern Lapeiqaun fault. From the regional tectonic setting, it appears that Mesozoic extension in northern Tibet to have occurred in a back arc setting during northward subduction of the Tethyan oceanic plate. The findings of Mesozoic extensional structures in northern Tibet suggest that compressive stress induced by collision of the Qiangtang and Lhasa terranes with Asia was not transmitted beyond northern Tibet. This in turn implies that the popularly inferred contractional setting for Mesozoic evolution of the Tian Shan north of Tibet needs a reevaluation based on a combination of both structural and sedimentological observations.
Fidelity of alkenone paleotemperatures in southern Cape Basin sediment drifts
Authors: Sachs Julian P. , Anderson Robert F.
Published: October 2003

Multiple geochemical analyses were performed in order to test the fidelity of alkenone paleotemperature reconstructions in southern Cape Basin sediment drifts. Sea surface temperatures (SSTs) derived from the alkenone unsaturation ratio, U37k′, in two drift cores (TN057‐21 and Ocean Drilling Program Site 1089) are nearly identical during the interval of overlapping analyses, MIS 4‐5c. SSTs in a nearby nondrift core (TN057‐6) covary with those in core TN057‐21 throughout MIS 1‐5c. While climatological SSTs overlying TN057‐21 and TN057‐6 are similar and consistent with reconstructed Holocene SSTs in the nondrift core, surface waters overlying TN057‐21 are ∼6°C colder than Holocene alkenone SSTs in the drift core. Temperatures remain ∼6°C warmer in TN057‐21 relative to TN057‐6 during the ∼100 kyr duration of the records. We hypothesize that alkenone‐derived SSTs in TN057‐21 are higher than climatological SSTs in the overlying surface water and those in TN057‐6 as a result of the winnowing and focusing of sedimentary alkenones produced in warmer waters to the north. Climatological SSTs in the central and northern Cape Basin are 16°–20°C. A −1.5‰ offset of fine fraction δ18O values relative to planktonic foraminifera in TN057‐21 supports this hypothesis. Temporal changes in sediment focusing were evaluated directly using uranium series radioisotopes. While higher sediment focusing factors would be expected to result in higher alkenone‐derived SSTs if sediment advection were the primary control on down‐core changes in alkenone‐derived SSTs, 230Th‐derived focusing factors indicate no such correlation exists. We conclude that alkenone paleotemperature reconstructions from southern Cape Basin drifts reliably record regional SST variations in the Cape Basin.
Parameterization of dust emission for the simulation of the yellow sand (Asian dust) event observed in March 2002 in Korea
Authors: Park Soon‐Ung , In Hee‐Jin
Published: October 2003

An extraordinarily severe yellow sand event was observed in Korea for the period of 21–23 March 2002. This event has been simulated using the three‐dimensional eulerian transport model with meteorological outputs of the Regional Data Assimilation and Prediction System (RDAPS) together with the statistically derived dust emission conditions from WMO 3 hourly synoptic reporting data for seven spring seasons (March–May) from 1996 to 2002 in East Asia. The statistically derived dust‐rise conditions with the help of the Chinese soil map in the source regions are found to be the threshold wind speed of 9.5, 7.5, 6.0 and 9.2 m s−1 and the upper limit of relative humidity of 60, 35, 30% and 40% in the Gobi, Sand, Loess and Mixed soil regions, respectively. These dust‐rise conditions are implemented to the eulerian long‐range transport model to simulate the extraordinarily intensive yellow sand event observed in Korea in terms of temporal and spatial variations of dust concentrations, starting and ending times of the yellow sand event over the Korean peninsula. It is found that the model simulates quite well the observed concentrations of more than 1,000 μg m−3 within the same order of magnitude and the starting and ending times of yellow sand in Korea within an hour. The spatial distribution of vertically integrated dust concentration in the model is quite well coincided with that of aerosol index obtained by total ozone mapping spectrometer (TOMS). The simulated dust particle sizes indicate that most of mass concentrations of dust in the source regions are mainly contributed by dust particles larger than PM10 whereas those at distant regions from the sources are largely attributed to the PM10 particles, suggesting the usefulness of the particle size spectrum in identifying the origin of a dust storm. The presently derived emission conditions enable to forecast the yellow sand event in Korea more reasonably than previously used conditions of threshold friction velocities.
Uncertainty and bias of surface ozone measurements at selected Global Atmosphere Watch sites
Authors: Klausen Jörg , Zellweger Christoph , Buchmann Brigitte , Hofer Peter
Published: October 2003

The Global Atmosphere Watch (GAW) program currently coordinates 22 ground‐based atmospheric background monitoring stations of global scope. The GAW World Calibration Centre for Surface Ozone, Carbon Monoxide and Methane (WCC‐EMPA) is responsible for tracing surface ozone measurements at these stations to the designated reference within the GAW program, the Standard Reference Photometer SRP 2 maintained at the National Institute of Standards and Technology (NIST). The recommended method for surface ozone measurements is based on UV absorption at 254 nm (Hg line). Repeated and regular intercomparisons of station instruments are necessary to achieve and maintain high and known data quality. In this paper, the traceability chain is explained, and standard uncertainties for each element are evaluated. Data of 26 intercomparisons performed at 14 stations between 1996 and 2002 are analyzed. On 23 occasions, the instruments passed the audit with “good” agreement, in one case with “sufficient” agreement. On 2 occasions, both first audits at the site, the audited instrument did not comply with the minimal data quality requirements. The best instruments in use exhibit a median absolute bias of approximately 0.32 ppbv and a standard uncertainty of approximately 0.8 ppbv (0–100 ppbv). The quantitative improvement of data quality as a result of repeated audits can be demonstrated with several stations.
Interaction between fungal endophytes and environmental stressors influences plant resistance to insects
Authors: Bultman Thomas L. , Bell Gregory D.
Published: October 2003

Neotyphodium coenophialum, an endophytic fungus that infects shoots of tall fescue (Festuca arundinacea), may protect its host from herbivory through production of alkaloids. Yet, the fungus can also modify plant resource allocation, regrowth dynamics, and drought tolerance, and these changes may also influence herbivores. We tested if N. coenophialum infection interacted with stress (drought or simulated herbivory) to modify plant resistance to insects. We assigned greenhouse plants to one of four treatments: 1) clipping at 3 cm above the soil surface, 2) drought stress during insect bioassays, 3) drought stress prior to insect bioassays, or 4) daily watering. Treatments were crossed with presence or absence of endophyte to give eight treatment combinations, and we assessed the performance of bird cherry‐oat aphid (Rhopalosiphum padi) and fall armyworm (Spodoptera frugiperda) feeding on plants in two separate experiments from each of the eight treatments. Aphids were placed into clip bags on leaf blades and allowed to reproduce parthenogenetically. Plant tissue was fed to third instar fall armyworm caterpillars until they molted into the fifth instar. Developmental time was recorded and larval growth was obtained gravimetrically. We also assessed total protein nitrogen (N) and loline alkaloids in plants.

 Total protein N was unaffected by endophyte infection. In contrast, stress influenced total protein N, but its effect varied with endophyte infection. Uninfected plants that were clipped had higher total protein N; this trend was absent in infected plants. Plants in drought stress had lower N, but only if they were infected. Lolines were nearly absent from uninfected plants. In infected plants they tended to be higher in clipped plants. The effect of endophyte infection differed between the two insects: aphid reproduction was reduced by the endophyte, but endophyte infection enhanced caterpillar performance. Both insects were affected by interactions between the endophyte and stress. Aphids were negatively affected by drought stress, but only when feeding on uninfected plants, while caterpillars showed the opposite response, displaying lower performance on drought stressed plants only if they were infected. Aphids reproduced faster on regrowth tissue (following damage by clipping) of uninfected plants, but endophyte infection cancelled this effect. In contrast, performance of caterpillars was not influenced by an interaction between damage and infection. We conclude that N. coenophialum does not provide universal resistance to insects. Endophyte‐mediated resistance varies with insect species and will be a complex function of environmental stress, including drought and prior damage.
Explaining adaptive shifts in body size on islands: a life history approach
Authors: Palkovacs Eric P.
Published: October 2003

The tendency for island populations to differ in body size from their mainland relatives has been well documented, but the mechanisms for these size changes remain speculative. Explanations have typically been based on ecological interactions that directly favor either an increase or decrease in body size. While it is clear that direct ecological interactions can influence body size, life history shifts present an alternative explanation for observed insular size trends across phylogenetic groups and trophic levels. Here I describe how decreased resource availability and reduced predation pressure, the same selective forces invoked by previous hypotheses, can operate to produce body size changes via the evolution of life history traits. This mechanism is more generally applicable than previous explanations and is consistent with much of the available data.
Effect of pinealectomy on plasma levels of insulin and leptin and on hepatic lipids in type 2 diabetic rats
Authors: Nishida Shigeru , Sato Ryuichiro , Murai Ichiro , Nakagawa Shigeki
Published: October 2003

Abstract: We previously reported that pharmacological melatonin administration to type 2 diabetic rats reduces hyperinsulinemia and improves the altered fatty‐acid metabolism. To determine whether melatonin deficiency exacerbates diabetes‐associated conditions, we investigated the effect of pinealectomy (i.e. melatonin‐deficiency) on plasma hormone levels and lipid metabolism in type 2 diabetic Otsuka Long‐Evans Tokushima Fatty (OLETF) rats. We compared levels of insulin and leptin, and hepatic lipids in pinealectomized OLETF (PO) rats, sham‐operated OLETF (SO) rats and sham‐operated healthy Long‐Evans Tokushima Otsuka (LETO) (SL) rats 16 and 30 wk after the operation. Plasma glucose and triglycerides were increased in SO and PO rats 30 wk after operation compared with age‐matched SL rats. Pinealectomy caused an increase in free cholesterol among the plasma lipids, as compared with SO rats. Sixteen weeks after pinealectomy, typical hyperinsulinemia was observed in PO rats (3.47‐fold increase, P < 0.01) as compared with SL rats, whereas at 30 wk, the plasma levels of insulin in PO and SO rats had decreased and there was no significant difference among the three groups. Hepatic triglycerides were increased (1.54‐fold, P < 0.005) in PO rats, compared with SO rats. Hepatic acyl‐CoA synthetase (ACS) activity was significantly augmented in PO rats at 30 wk (10%, P < 0.01 versus SO group), while microsomal triglyceride transfer protein (MTP) decreased (−27% versus SO, P < 0.05); thus, the increased ACS activity and decreased MTP might have a role in the accumulation of hepatic triglycerides in PO rats. In summary, pinealectomy causes severe hyperinsulinemia and accumulation of triglycerides in the liver, probably owing to the loss of the nocturnal melatonin surge.
Expression of Interleukin‐1β mRNA in Murine Uterine and Gestational Tissues: Relationship with Gestational Age1
Authors: SATO TIMOTHY A. , GUPTA DEEPAK K. , KEELAN JEFFREY A. , MARVIN KEITH W. , MITCHELL MURRAY D.
Published: October 2003

PROBLEM: The pro‐inflammatory cytokine interleukin (IL)‐1β has been shown to stimulate the production of prostaglandins (PG) in gestational tissues. Increased PG synthesis is considered a key step in the initiation of labor both at term and preterm. In this study, IL‐1β mRNA in the uterus and gestational tissues of mice during mid to late pregnancy was studied to characterize its tissue specific as well as gestational age expression.  METHOD OF STUDY: Gestational tissues (placenta, decidual cap and fetal membranes), uterus, and cervix were collected from pregnant mice during gestation. Total RNA was isolated and probed for the expression of IL‐1β mRNA.  RESULTS: There was a significantly increased expression of IL‐1β mRNA in the uterus on day 18 of pregnancy. In the decidual caps, there was increased expression of IL‐1β mRNA on day 14 of pregnancy and a decrease in expression with the onset of labor. In the fetal membranes and placenta, IL‐1β mRNA expression significantly increased on days 14 and 18 of pregnancy, respectively, and then remained elevated for the duration of pregnancy. In the cervix, there was a decrease in expression with labor onset.  CONCLUSIONS: The increases in IL‐1β mRNA in the fetal membranes and placenta late in pregnancy are consistent with a localized, tissue specific inflammatory activation involved in the initiation of parturition.
The Receptors and Role of Angiotensin II in Knee Joint Blood Flow Regulation and Role of Nitric Oxide in Modulation of Their Function
Authors: NAJAFIPOUR H. , KETABCHI F.
Published: October 2003

Objectives: Angiotensin‐converting enzyme (ACE) upregulation in the stroma cells of arthritis rheumatoid joints may produce a higher tissue concentration of angiotensin II (angII), which is a vasoconstrictor and mitogen factor that causes local hypoxia and synovial proliferation. No study in the literature has examined the role of angII in joint blood flow (JBF) regulation and the potential effect of ACE inhibitors on JBF.

Methods: The study was performed on 20 Dutch white rabbits to examine the JBF response to angII, angII receptor subtypes, and the role of nitric oxide (NO) in angII effects in knee joint blood vessels. Drugs were administered locally through retrograde saphenous artery cannulation. Joint vascular resistance (JVR) was calculated by dividing the arterial blood pressure by the JBF.

Results: AngII increased JVR dose dependently. The angII type 1 (AT1) receptor antagonist losartan did not change the basal JVR but completely blocked the effect of angII on JVR. Nω‐nitro‐L‐arginin methyl ester (L‐NAME) increased JVR by a mean (±SEM) of 25.8 ± 8.7% (p < 0.05) but did not affect the joint vessel response to angII and losartan.

Conclusions: AngII receptors are from the AT1 subtype in normal joint blood vessels, but angII plays no significant role in JBF regulation. The basal release of NO plays a role in resting JBF regulation, but NO does not affect the AT1 receptor‐mediated vasoconstriction of joint blood vessels.
Abstention, alcohol use and risk of myocardial infarction in men and women taking account of social support and working conditions: the SHEEP case–control study
Authors: Romelsjö Anders , Branting Maria , Hallqvist Johan , Alfredsson Lars , Hammar Niklas , Leifman Anders , Ahlbom Anders
Published: October 2003

Aims  Very few studies indicating that low–moderate alcohol consumption protects from myocardial infarction (MI) controlled for social support and working conditions, which could confound the findings. Therefore, a first aim was to study the risk of non‐fatal and total MI in relation to volume of alcohol consumption and measures of social support and working conditions. A second aim was to analyse the impact of the volume of earlier alcohol use in abstainers.

Design  Data came from a case–control study, the Stockholm Heart Epidemiology Program (SHEEP), including first MI among Swedish citizens 45–70 years old.

Setting  Stockholm County 1992–94.

Participants  There were 1095 cases of MI in men and 471 in women (928 and 372 were non‐fatal), and 2339 living controls from the general population.

Measurement  Information about alcohol use at different periods in life and job strain, social anchorage and life control besides pre‐existing health problems, smoking, physical activity, socio‐economic status and marital status was obtained by a questionnaire from the cases and the controls.

Findings  In multivariate logistic regression analyses, the relative risk for MI (especially non‐fatal) was reduced among alcohol consumers. RR for non‐fatal MI was 0.52 (95% confidence intervals 0.32, 0.85) in men with a consumption of 50–69.9 g 100% ethanol/day and 0.21 (95% confidence interval 0.06, 0.77) in women with a consumption of 30 g or more per day (reference category 0.1–5 g 100% ethanol/day). Men who were abstainers during the previous 1–10 years and with an earlier average consumption of 5–30 g 100% ethanol/day had a significantly lower relative risk compared to such abstainers with an earlier higher consumption. Earlier consumption among abstainers may also have an impact on gender differences in MI. Analyses showed positive interaction between abstention and low life‐control in women, but only 4% of the female cases were due to this interaction. There were no other interactions between measures of alcohol use and social anchorage, life control and working situations.

Conclusion  Alcohol use had a protective impact on MI, with little impact of job strain, social anchorage and life control, giving increased support for a protective impact of low‐moderate alcohol use. The level of previous alcohol consumption among male 1–10‐year‐long abstainers influenced the risk of MI.
Relationship between stiffness, internal cell pressure and shape of outer hair cells isolated from the guinea‐pig hearing organ
Authors: CHAN E. , ULFENDAHL M.
Published: October 2003

The mechanical properties of outer hair cells are of importance for normal hearing, and it has been shown that damage of the cells can lead to a reduction in the hearing sensitivity. In this study, we measured the stiffness of isolated outer hair cells in hyper‐ and hypotonic conditions, and examined the change in stiffness in relation to the corresponding changes in internal cell pressure and cell shape. The results showed that the axial stiffness of isolated outer hair cells (30–90 μm in length, 8–12 μm in diameter), ranging from 0.13–5.39 mN m−1, was inversely related to cell length. Exposure to hyper‐ and hypotonic external media with a small percentage change in osmolality caused a similar magnitude of change in cell length and cell diameter, but an average 60% change in cell stiffness. Therefore, a moderate osmotic change in the external medium can lead to a significant alteration in cell stiffness. The findings thus indicate an important contribution of internal cell pressure to cell stiffness.