243 research outputs found
Effect of a temperature dependent effective quasiparticle mass on the surface impedance of YBa2Cu3O7-x
No full textEffect of a temperature dependent effective quasiparticle mass on the surface impedance of YBa2Cu3O7-x
No full textThe temperature dependent surface impedance Zs(T) of single-crystalline YBa2Cu3O7-x (YBCO) was analyzed within the two-fluid
model in terms of the fraction of paired charge carriers, fs(T), and of
the quasiparticle scattering time T(T). The usual approach was extended by
considering a temperature dependent effective quasiparticle mass m*(T), which
results from a strong electron-phonon interaction. This effect must not be neglected
in the description of high-temperature superconductors due to the large ratio of
Tc to the Debye temperature TD. The temperature dependence of
the penetration depth, λ(T), of high-quality YBCO crystals and films could
be described with an electron-phonon coupling constant Λ0=4, and using
fs(T)=1-(T/T)2.8 as an approximation of the BCS theory.
Different trial phonon spectra were encountered in terms of their ability to reproduce
the λ(T)-data. The scattering time T(T) was described by the
Bloch-Grüneisen formalism with TD=460K. Assuming an Einstein
spectrum with kBTc/ñΩn=0.24, a residual
resistivity pr=1.8μΩcm and a fraction of unpaired
quasiparticles ξ0.04 at T=0Kyielded a surprisingly good
agreement of the model with T=0K-data measured at 87 GHz with a
high-quality epitaxial YBCO film between T=4K and Tc. While an
exact reproduction of the surface impedance asks for a rigorous theoretical computation,
our analysis demonstrates that strong electron-phonon coupling is relevant for
discussing the unconventional transport properties of YBCO
The long acidic tail of High Mobility Group Box 1 (HMGB1) protein forms an extended and flexible structure that interacts with specific residues within and between the HMG boxes
No full textProteomic and Postproteomic Characterization of Keratan Sulfate-Glycanated Isoforms of Thyroglobulin and Transferrin Uniquely Elaborated by Papillary Thyroid Carcinomas.
No full textPrevious studies have suggested that surface components of papillary thyroid carcinoma (PTC) cells may be aberrantly glycanated, but the precise nature of these molecules has not been unveiled nor documented to be of clinical relevance. A monoclonal antibody was raised against a unique keratan sulfate (KS) determinant and used to differentially screen benign and malignant thyroid tissue for the expression of components carrying these moieties. In a total of 349 cases of benign and malignant thyroid lesions, 100% of the 115 PTC cases examined (including various histological subtypes) were found to contain KS-bearing molecules, whereas these were virtually absent from benign tissues and other thyroid tumors, with the exception of 21% of the follicular carcinoma cases analyzed. A composite immunoaffinity chromatography, immunochemistry, and mass spectrometric approach revealed that the PTC-specific KS-bearing macromolecules were unique glycoforms of thyroglobulin and transferrin. Combined, reciprocal immunoprecipitation and Western blotting further indicated that the former glycoform predominated and that most of the transferrin produced by PTC was glycanated with KS moieties. Fluorescent keratanase II-based fingerprinting of the KS moieties bound to these isoforms further demonstrated several PTC-specific peculiarities: 1) that a considerable portion of the moieties was covalently attached via a novel core protein linkage structure; 2) they had an unusual extended average length; 3) an unusual relative ratio of highly sulfated disaccharides terminating with (2-3)-linked N-acetylneuraminic acid capping residues; and 4) a novel unidentified oligosaccharide moiety at the nonreducing terminus. Comparative analysis of the relative distribution of transferrin in benign versus PTC tissues highlighted a marked malignancy-associated abundance of the molecule, with a >75% frequency in expression in PTC. These findings demonstrate that PTC cells synthesize unique post-translationally modified thyroglobulin and transferrin variants in situ that may be directly exploitable for diagnosis, through histological and noninvasive cytological procedures; for devising novel strategies for antibody-guided imaging of this tumor in vivo; and for postsurgery follow-up of PTC patients
Recent Developments in Carbonate Sedimentology in Central Europe
No full textIn the field of sedimentary research, ever increasing emphasis has been put on the investigations of carbonates and carbonate rocks during the past 30 years. It is thus quite natural that in Central Europe - where c1assical carbonate in vestigations have already been carried out 100 years ago - numerous scholars turned to the study of this sediment type. On the occasion of a visiting professorship of G. M. FRIEDMAN at the Labora torium fr Sedimentforschung, Heidelberg University, a seminar on "Recent Developments of Carbonate Sedimentology in Central Europe" was held in July 1967. 90 persons involved in carbonate investigations participated, and 35 lectures were held. The present volume contains 30 papers summarizing the different subjects of the seminar. Of course these contributions only represent a small part of the work actually performed in the field of carbonate research in Central Europe. We believe, however, that they give a general survey of the work and the working methods employed in the different sectors of carbonate investigations. One of the purposes of the present symposium is to acquaint the English speaking countries with our recent results which usually - due to the language barrier - are not accessible to the
"New" lunar meteorites: Impact melt and regolith breccias and large-scale heterogeneities of the upper lunar crust
No full textWe have analyzed nine highland lunar meteorites (lunaites) using mainly INAA. Several of these rocks are difficult to classify. Dhofar 081 is basically a fragmental breccia, but much of its groundmass features a glassy-fluidized texture that is indicative of localized shock melting. Also, much of the matrix glass is swirly-brown, suggesting a possible regolith derivation. We interpret Dar al Gani (DaG) 400 as an extremely immature regolith breccia consisting mainly of impact-melt breccia clasts; we interpret Dhofar 026 as an unusually complex anorthositic impact-melt breccia with scattered ovoid globules that formed as clasts of mafic, subophitic impact melt. The presence of mafic crystalline globules in a lunar material, even one so clearly impact-heated, suggests that it may have originated as a regolith. Our new data and a synthesis of literature data suggest a contrast in Al2O3- incompatible element systematics between impact melts from the central nearside highlands, where Apollo sampling occurred, and those from the general highland surface of the Moon. Impact melts from the general highland surface tend to have systematically lower incompatible element concentration at any given Al2O3 concentration than those from Apollo 16. In the case of Dhofar 026, both the bulk rock and a comparatively Al-poor composition (14 wt% Al2O3, 7 g/g Sm) extrapolated for the globules, manifest incompatible element contents well below the Apollo 16 trend. Impact melts from Luna 20 (57E) distribute more along the general highland trend than along the Apollo 16 trend. Siderophile elements also show a distinctive composition for Apollo 16 impact melts: Ni/Ir averaging ~1.8x chondritic. In contrast, lunaite impact-melt breccias have consistently chondritic Ni/ Ir. Impact melts from Luna 20 and other Apollo sites show average Ni/Ir almost as high as those from Apollo 16. The prevalence of this distinctive Ni/Ir ratio at such widely separated nearside sites suggests that debris from one extraordinarily large impact may dominate the megaregolith siderophile component of a nearside region 2300 km or more across. Highland polymict breccia lunaites and other KREEP-poor highland regolith samples manifest a strong anticorrelation between Al2O3 and mg. The magnesian component probably represents the chemical signature of the Mg-suite of pristine nonmare rocks in its most pure form, unaltered by the major KREEP-assimilation that is so common among Apollo Mg-suite samples. The average composition of the ferroan anorthositic component is now well constrained at Al2O3 ~29-30 wt(implying about 17-19 wt% modal mafic silicates), in good agreement with the composition predicted for flotation crust over a ferroan magma ocean (Warren 1990)
Exogenous High-Mobility Group Box 1 protein induces myocardial regeneration following infarction via enhanced cardiac c-kit+ cell proliferation and differentiation
No full textSAFT-γ force field for the simulation of molecular fluids: 3. Coarse-grained models of benzene and hetero-group models of n-decylbenzene
No full textIn the first paper of this series [C. Avendao, T. Lafitte, A. Galindo, C.S. Adjiman, G. Jackson, and E.A. Mller, J. Phys. Chem. B 115, 11154 (2011)] our methodology for the development of accurate coarse-grained (CG) SAFT-force fields for the computer simulation of molecular fluids was introduced with carbon dioxide as a particular case study. The procedure involves the use of a molecular-based equation of state to obtain effective intermolecular parameters (from experimental fluid phase equilibrium data) appropriate for molecular simulation over a wide range of fluid conditions. We now extend the methodology to develop coarse-grained models for benzene (C6 H6) that can be used in fluid phase simulations. Our SAFT-CG force fields for benzene consist of a simple single-segment spherical model, and a rigid three-segment ring structure of tangent spherical groups interacting via Mie (generalized Lennard-Jones) segment-segment interactions. The description of the fluid phase behaviour of benzene with our simplified CG force fields is found to be comparable to that obtained with the more sophisticated models commonly used in the field; a marked improvement is seen with our SAFT-models for the vapour pressure, particularly at lower temperatures. These models of benzene together with the previously developed SAFT-three-segment chain model of n-decane are used to develop hetero-group force fields for n-decylbenzene, in the spirit of a group contribution methodology. In our approach, the parameters of the phenyl and n-decyl groups are obtained transferably from the individual models of benzene and n-decane, respectively, and the unlike energetic parameters between the phenyl and decyl segments can be obtained from vapour-liquid equilibria data for n-decylbenzene using the SAFT-equation of state. The resulting CG hetero-group models are found to describe the fluid properties of n-decylbenzene over a wide range of conditions, exemplifying how our approach can be used as a group contribution methodology. This is the first example of the development of hetero-group SAFT-force fields for molecules formed from Mie segments of different size, energy, softness/hardness, and range. © 2012 Taylor & Francis
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