bluuebunny/crossref_metadata_2025_split huggingface dataset:
Carcinogenicity of 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin in experimental models
Authors: Knerr Stefanie , Schrenk Dieter 
Published: September 2006

AbstractThe contaminant 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD) is a prototype compound of a whole class of halogenated aromatic hydrocarbons termed ‘dioxinlike’ contaminants present in food, human tissue, mothers milk, and environmental samples. Among the various adverse effects caused by TCDD in animal experiments, its carcinogenic effects caused particular concern. In rodents, long‐term TCDD treatment leads to the development of tumors of the liver, thyroid, lung, skin, oral cavity and other sites. The occurrence of liver tumors mainly observed in female rats has been used as a basis for quantitative cancer risk assessment for TCDD. TCDD does not behave like a ‘complete carcinogen’, i. e. no DNA binding of the parent compound or metabolites thereof could be detected. However, enhanced oxidative damage of hepatic DNA was observed, probably resulting from a dramatic induction of cytochrome P450 enzymes, which are under the regulatory, transcriptional control of the TCDD‐activated aryl hydrocarbon receptor. The marked enhancement of TCDD‐related oxidative liver DNA damage in rats by estrogens warrants further mechanistic investigation. Furthermore, TCDD acts as a tumor promoter, i. e. it facilitates the growth of putative preneoplastic hepatic lesions after initiation with a complete carcinogen. The mechanisms underlying this effect may be related to altered intracellular signaling involving pronounced changes in the phosphorylation pattern of proteins regulating growth and apoptosis. These effects are thought to result in an enhanced survival of preneoplastic cells, some of which can undergo further steps on the way to malignancy. In summary, a better understanding of the mechanisms of the carcinogenicity of TCDD is mandatory to provide a rational basis for a better inter‐species extrapolation. The final aim of these efforts is a more reliable risk assessment for the carcinogenic potency of the class of dioxinlike contaminants in humans.
Comparison of chronic toxicity and carcinogenicity of 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD) in 2‐year bioassays in female Sprague‐Dawley rats
Authors: Walker Nigel J. , Wyde Michael E. , Fischer Lawrence J. , Nyska Abraham , Bucher John R. 
Published: September 2006

AbstractThe cancer bioassay for 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD) conducted by the Dow Chemical company in the mid 70s has been used extensively for conducting quantitative cancer risk assessments for human exposure to TCDD. More recently the National Toxicology Program (NTP) conducted a cancer bioassay of similar design as part of its evaluation of the dioxin toxic equivalency factor methodology. This report compares the design and the results of these two cancer bioassays. This comparison confirms, in most cases, previously published and widely used carcinogenic response characteristics with respect to dose, time course, organ selectivity, tumor type and maximum intensity of TCDD‐induced carcinogenicity and toxicity in the Sprague‐Dawley rat. Specifically, increases in the incidences of neoplasms were seen in both studies in the liver, lung and oral mucosa. The most notable difference was the significant increase in the incidence of cholangiocarcinoma of the liver seen in the NTP study but not in the Dow study. The experimental designs for the two studies are similar but some protocol parameters differed, such as vehicle, dosing schedule, diet and rat sub‐strain utilized. Differences in the shapes of the dose response curves for several neoplasms were noted between the studies, with the NTP study showing non‐linearity for all neoplasms. This may result from differences in the experimental protocols as well as divergence in the biological behavior of the different stocks of Sprague‐Dawley rat strains used.
NMR assessment of the global shape of a non‐labelled DNA dodecamer containing a tandem of GT mismatches
Authors: Alvarez‐Salgado Francisco , Desvaux Hervé , Boulard Yves 
Published: September 2006

AbstractWe have carried out a solution study of two non‐labelled self‐complementary DNA dodecamers d(GACTGTACAGTC)2 and d(GACTGTGCAGTC)2 by NMR, the second sequence composed of two GT mismatches. Structures were determined using distances extracted from NOE effects alone or using both NOE and RDC constraints, measured in three different liquid crystalline media. We ensured that our data on the influence of the mesogen on the DNA structures, and the way in which the RDCs were incorporated as constraints in the protocol refinement, were consistent. We also tested the influence of different sets of RDCs and the best means of optimizing the calculation of Da and R. Resolution and accuracy of the ten best energy final structures were compared. The addition of a small set of RDC constraints significantly improves the final determined structures. We took advantage of the specificity of the RDC, i.e. it contains orientational information, and explored the global shape of the DNA duplexes; it was found that the duplexes do not have a large curvature. For the GT base pair, we observed, in this particular sequence (tandem of GT mismatches), a new pattern of base pairing, which involved the formation of a bifurcated hydrogen bond. Copyright © 2006 John Wiley & Sons, Ltd.
Discontinuous Galerkin framework for adaptive solution of parabolic problems
Authors: Kulkarni Deepak V. , Rovas Dimitrios V. , Tortorelli Daniel A. 
Published: September 2006

AbstractNon‐conforming meshes are frequently employed in adaptive analyses and simulations of multi‐component systems. We develop a discontinuous Galerkin formulation for the discretization of parabolic problems that weakly enforces continuity across non‐conforming mesh interfaces. A benefit of the DG scheme is that it does not introduce constraint equations and their resulting Lagrange multiplier fields as done in mixed and mortar methods. The salient features of the formulation are highlighted through an a priori analysis. When coupled with a mesh refinement scheme the DG formulation is able to accommodate multiple hanging nodes per element edge and leads to an effective adaptive framework for the analysis of interface evolution problems. We demonstrate our approach by analysing the Stefan problem of solidification. Copyright © 2006 John Wiley & Sons, Ltd.
Reduction of substructural interface degrees of freedom in flexibility‐based component mode synthesis
Authors: Markovic Damijan , Park K. C. , Ibrahimbegovic Adnan 
Published: September 2006

AbstractA flexibility‐based component mode synthesis (CMS) is proposed for reduced‐order modelling of dynamic behaviour of large structures. The approach employs partitioning via the localized Lagrange multiplier method. The use of the localized Lagrange multipliers leads to, unlike the classical Lagrange multipliers, a linearly independent set of interface forces without any redundancies at multiply connected interface nodes. The flexibility‐based CMS method has shown significant advantages over the classical Craig–Bampton method. A key feature of the method is its substructural mode selection criterion that is independent of loading conditions. Unlike the majority of available CMS approaches, where one retains the full dimension of partition boundary degrees of freedom (DOFs), the flexibility‐based method allows to reduce significantly the interface DOFs. The reduction of interface DOFs represents the major contribution of the present communication. The efficiency of the proposed approach is demonstrated on an analysis of a simple plate partitioned and of a more complex 3D structure, both partitioned into several substructures. Copyright © 2006 John Wiley & Sons, Ltd.
Gene profiling of cathepsin K deficiency in atherogenesis: profibrotic but lipogenic
Authors: Lutgens SPM , Kisters N , Lutgens E , van Haaften RIM , Evelo CTA , de Winther MPJ , Saftig P , Daemen MJAP , Heeneman S , Cleutjens KBJM 
Published: September 2006

AbstractRecently, we showed that cathepsin K deficiency reduces atherosclerotic plaque progression, induces plaque fibrosis, but aggravates macrophage foam cell formation in the ApoE −/− mouse. To obtain more insight into the molecular mechanisms by which cathepsin K disruption evokes the observed phenotypic changes, we used microarray analysis for gene expression profiling of aortic arches of CatK −/−/ApoE −/− and ApoE −/− mice on a mouse oligo microarray. Out of 20 280 reporters, 444 were significantly differentially expressed (p‐value of < 0.05, fold change of ≥ 1.4 or ⩽− 1.4, and intensity value of > 2.5 times background in at least one channel). Ingenuity Pathway Analysis and GenMAPP revealed upregulation of genes involved in lipid uptake, trafficking, and intracellular storage, including caveolin − 1, − 2, − 3 and CD36, and profibrotic genes involved in transforming growth factor β (TGFβ) signalling, including TGFβ2, latent TGFβ binding protein‐1 (LTBP1), and secreted protein, acidic and rich in cysteine (SPARC), in CatK −/−/ApoE −/− mice. Differential gene expression was confirmed at the mRNA and protein levels. In vitro modified low density lipoprotein (LDL) uptake assays, using bone marrow derived macrophages preincubated with caveolae and scavenger receptor inhibitors, confirmed the importance of caveolins and CD36 in increasing modified LDL uptake in the absence of cathepsin K. In conclusion, we suggest that cathepsin K deficiency alters plaque phenotype not only by decreasing proteolytic activity, but also by stimulating TGFβ signalling. Besides this profibrotic effect, cathepsin K deficiency has a lipogenic effect owing to increased lipid uptake mediated by CD36 and caveolins. Copyright © 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Proteomics and metabolomics: The molecular make‐up of toxic aromatic pollutant bioremediation
Authors: Singh Om V. 
Published: September 2006

AbstractMicrobial‐mediated attenuation of toxic aromatic pollutants offers great potential for the restoration of contaminated environments in an ecologically acceptable manner. However, incomplete biological information regarding the regulation of growth and metabolism in many microbial communities restricts progress in the site‐specific mineralization process. In the postgenomic era, recent advances in MS have allowed enormous progress in proteomics and elucidated many complex biological interactions. These research forefronts are now expanding toward the analysis of low‐molecular‐weight primary and secondary metabolites analysis, i.e., metabolomics. The advent of 2‐DE in conjunction with MS offers a promising approach to address the molecular mechanisms of bioremediation. The two fields of proteomics and metabolomics have thus far worked separately to identify proteins and primary and secondary metabolites during bioremediation. A simultaneous study combining functional proteomics and metabolomics, i.e., proteometabolomics would create a system‐wide approach to studying site‐specific microorganisms during active mineralization processes. This article deals with advances in environmental proteomics and metabolomics and advocates the simultaneous study of both technologies to implement cell‐free bioremediation.
Proteomic analysis of cancer tissues: Shedding light on carcinogenesis and possible biomarkers
Authors: Kuramitsu Yasuhiro , Nakamura Kazuyuki 
Published: September 2006

AbstractLung, gastric, colorectal, pancreatic, and esophageal cancers, as well as hepatocellular carcinoma (HCC), were the six most common and highly fatal cancers for Japanese men in Japan in 2003, while for women uterine cervical cancer could also be added to this list. To identify diagnostic or therapeutic biomarkers for these cancers, investigators are nowadays performing proteomic analyses of cancer tissues and cells, and revealing a large number of molecules which are diagnostic, prognostic and informative of carcinogenesis. From reports of proteomic analyses of cancerous tissues and noncancerous tissues sampled from HCC, and pancreatic, esophageal, gastric, colorectal, lung and uterine cervical cancers, we classified the proteins into digestive enzymes, growth factors, cell adhesion molecules, calcium‐binding proteins, proteases, protease inhibitors, transporter proteins, structural molecules, apoptosis inhibitor, molecular chaperone, as well as proteins related to cell growth, cell differentiation, cell transformation, tumor invasion, carcinogen metabolism, and others. The aim of this study was to understand carcinogenesis of major cancers from a proteomics perspective using samples from cancer patients, and to elucidate their tumor biomarkers.
Chemistry meets proteomics: The use of chemical tagging reactions for MS‐based proteomics
Authors: Leitner Alexander , Lindner Wolfgang 
Published: September 2006

AbstractAs proteomics matures from a purely descriptive to a function‐oriented discipline of the life sciences, there is strong demand for novel methodologies that increase the depth of information that can be obtained from proteomic studies. MS has long played a central role for protein identification and characterization, often in combination with dedicated chemical modification reactions. Today, chemistry is helping to advance the field of proteomics in numerous ways. In this review, we focus on those methodologies that have a significant impact for the large‐scale study of proteins and peptides. This includes approaches that allow the introduction of affinity tags for the enrichment of subclasses of peptides or proteins and strategies for in vitro stable isotope labeling for quantification purposes, among others. Particular attention is given to the study of PTMs where recent advancements have been promising, but many interesting targets are not yet being addressed.
Hole growth as a microrheological probe to measure the viscosity of polymers confined to thin films
Authors: Roth Connie B. , Dutcher John R. 
Published: September 2006

AbstractWe review recent hole growth measurements performed at elevated temperatures in freely‐standing polystyrene (PS) films, using optical microscopy and a differential pressure experiment (DPE). In the hole growth experiments, which were performed at temperatures close to the bulk glass‐transition temperature of PS, T = 97 °C, we find evidence for nonlinear viscoelastic effects, which markedly affect the growth of holes in freely‐standing PS films. The hole radius R initially grew linearly with time t before undergoing a transition to exponential growth characterized by a growth time τ. The time scale τ1 for the decay of the initial transient behavior prior to reaching steady state was consistent with the convective constraint release mechanism of the tube theory of entangled polymer dynamics, while the characteristic hole growth times τ of the holes were consistent with significant reductions in viscosity of over eight orders of magnitude with increasing shear strain rate due to shear thinning. DPE measurements of hole growth on very thin freely‐standing films revealed that hole formation and growth occurs only at temperatures that are comparable to or greater than T, even for films for which the Tg value was reduced by many tens of degrees Celsius below the bulk value. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B:Polym Phys 44: 3011–3021, 2006
Novel catalysts for low temperature synthesis of single wall carbon nanotubes
Authors: Rümmeli M. H. , Grüneis A. , Löffler M. , Jost O. , Schönfelder R. , Kramberger C. , Grimm D. , Gemming T. , Barreiro A. , Borowiak‐Palen E. , Kalbác M. , Ayala P. , Hübers H.‐W. , Büchner B. , Pichler T. 
Published: September 2006

AbstractLow temperature single wall carbon nanotubes (SWCNT) synthesis is attractive as it would allow their synthesis to be compatible with microelectronics (below 500 °C) or biomolecular electronics (160 °C). We show that the presence of oxygen, introduced in the form of metal oxides, allows metals not normally associated with nanotubes synthesis to become active for the synthesis of SWCNT using laser ablation. Further, the results show metals with low melting points can be used, enabling SWCNT to be synthesized at low temperature (down to room temperature). At these low temperatures their nucleation cannot be explained via fullerene nucleation. We suggest a growth mechanism that places a stable oxidized ring as the root cause for the growth of SWCNT. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Pressure‐dependent infrared spectroscopy on the fullerene rotor–stator compound C60–C8H8
Authors: Kuntscher C. A. , Frank S. , Kamarás K. , Klupp G. , Kováts É. , Pekker S. , Bényei Gy. , Jalsovszky I. 
Published: September 2006

AbstractWe carried out infrared transmission measurements of C60–C8H8 as a function of pressure (0–10 GPa) at room temperature. The kinks in the pressure dependences of the frequencies of the molecular vibrations suggest the occurrence of an orientational ordering transition at around 0.8 GPa. The change in the infrared spectrum indicates symmetry lowering in the high‐pressure phase. Furthermore, our data show that the vibrations of C8H8 survive up to a higher pressure than those of C60, suggesting a shielding of the C8H8 molecules against pressure. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photoluminescence microscopy of as‐grown individual single‐walled carbon nanotubes on Si/SiO2 substrates
Authors: Kiowski Oliver , Lebedkin Sergei , Kappes Manfred M. 
Published: September 2006

AbstractWe present far‐field photoluminescence (PL) imaging at room temperature of tens of micrometer long individual single‐walled carbon nanotubes (SWNTs) grown and measured directly on a Si/SiO2 surface. The SWNTs are grown by Chemical Vapour Deposition (CVD) with ethanol as carbon source and contact the surface with their full length. We detect the PL and its variations along SWNTs in a home‐built laser microscope with a spatial resolution of ∼400 nm. We are able to reliably assign (n, m)‐structure of SWNTs by measuring PL spectra in the range of 800–1600 nm as function of the excitation wavelength varying between 710 and 860 nm. This allows us to check structural integrity (changes of helicity) along the tube. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electrical transport measurements of nanotubes with known (n, m) indices
Authors: Chandra Bhupesh , Caldwell Robert , Huang Mingyuan , Huang Limin , Sfeir Matthew Y. , O'Brien Stephen P. , Heinz Tony F. , Hone James 
Published: September 2006

AbstractBecause subtle changes in physical structure (chirality) can cause the electronic structure of carbon nanotubes to vary from metallic to semiconducting, the goal of fully controlled nanotube device fabrication has proved elusive. Using a mechanical transfer technique in parallel with optical characterization, we have achieved the goal of placing ‘the nanotube we want, where we want it’. Long nanotubes are grown by CVD across a slit etched through a Si wafer and then examined by Rayleigh scattering. By combining this technique with structural characterization by electron diffraction, we are able to map each spectrum to a unique (n, m) structure. After structural characterization, a chosen nanotube can be transferred to a substrate in the desired location, and devices fabricated using standard e‐beam lithography techniques. We have fabricated a number of devices in this manner and are beginning to fully explore the detailed relationship between structure and transport. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of electron and ultraviolet irradiation on aligned carbon nanotube fibers
Authors: Mikó Csilla , Seo Jin Won , Gaál Richárd , Kulik Andrzej , Forró László 
Published: September 2006

AbstractWe carried out in situ Young's modulus and electrical resistivity measurements on macroscopic oriented ropes of singlewall carbon nanotubes under ultraviolet irradiation. Increases of both the electrical conductivity and the mechanical strength have been observed. These phenomena are explained by the photochemistry between the functional groups on the surface of singelwall nanotubes and dimethyl‐formamide molecules are trapped between the nanotubes. In contrast to high energy electrons during electron irradiation, the photon energy of the ultraviolet irradiation is not sufficient to displace the carbon atoms in the nanotube, therefore the graphitic structure of the tubes remains intact. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Carbon nanotube optoelectronics
Authors: Avouris Ph. , Chen J. , Freitag M. , Perebeinos V. , Tsang J. C. 
Published: September 2006

AbstractIn this tutorial we review the optical and electro‐optical properties of single‐walled carbon nanotubes (CNTs). The nature of the excited states of CNTs, their production by photon and electrical excitation and their decay are analyzed. Two types of single CNT light emitters based on ambipolar e–h recombination and a novel unipolar internal impact excitation mechanism are discussed. The reverse process of light detection through photoconduction is also briefly considered. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Four‐terminal measurements of SWNTs using MWNTs as voltage electrodes
Authors: Gao B. , Chen Y. F. , Fuhrer M. S. , Glattli D. C. , Bachtold A. 
Published: September 2006

AbstractWe report on electron transport measurements of single‐wall carbon nanotubes in a four‐terminal configuration with noninvasive voltage electrodes. The voltage drop is detected using multiwalled carbon nanotubes while the current is injected through nanofabricated Au electrodes. Measurements are carried at high temperature so that the four‐terminal resistance directly gives the intrinsic resistance. The resistance is shown to result from weak disorder and from quantum interference effect corrections. In addition, we present Coulomb blockade measurements. The length of the quantum dot that is determined from the level spacing equals the separation between the Au electrodes. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
DNA‐decorated carbon nanotubes for chemical sensing
Authors: Johnson A. T. Charlie , Staii Cristian , Chen Michelle , Khamis Sam , Johnson Robert , Klein M. L. , Gelperin A. 
Published: September 2006

AbstractWe demonstrate a versatile class of nanoscale chemical sensors based on single‐stranded DNA (ssDNA) for chemical recognition and single‐walled carbon nanotube field effect transistors (SWNT FETs) for electronic read‐out. SWNT FETs with a nanoscale coating of ssDNA respond to vapors that cause no detectable conductivity change in bare devices. Sensor responses differ in sign and magnitude for different gases and can be tuned by choice of the ssDNA base sequence. Sensors respond and recover rapidly (seconds), and the sensor surface is self‐regenerating. Preliminary results of all‐atom molecular dynamics simulations agree with experiment. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electric transport properties and 1H NMR study of the fullerene‐like WS2 nanoparticles
Authors: Kopnov Frieda , Leitus Gregory , Yoffe Alex , Feldman Isai , Panich A. M. , Tenne Reshef 
Published: September 2006

AbstractElectrical resistivity and Hall measurements, of pellets compacted from IF ‐WS2 nanoparticles and 2H‐WS2 powder were done. Electrical transport measurements were carried out on pellets by the van der Pauw method in a wide temperature range. Arrhenius plots for conductivities of the WS2 samples (2H, IF and IF +treatment) exhibit marked variations in (∂ ln σT –1)/∂T –1 with temperature. Resistivity of IF ‐WS2 pellets is higher than that of 2H‐WS2 pellets. It was found that the electrical properties of IF ‐WS2 powder vary with aposteriory heat treatment under vacuum. The 1H NMR measurements show that the prepared product contains water (and possibly some hydrogen) molecules that occupy the voids in the central part of the fullerene‐like nanoparticles and the nanopores between the adhering IF ‐WS2 particles. Defects in the IF ‐WS2 structure, arising due to the strain release during the folding of the layers, may result in additional sites for the absorbed water. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)