bluuebunny/crossref_metadata_2025_split huggingface dataset:
A strategy for constructing C-sialosides based on Ireland-Claisen rearrangement and its application for synthesis of CF2-linked ganglioside GM4 analog
Authors: Sodeoka Mikiko , Hirai Go , Watanabe Toru , Miyagi Taeko 
Published: February 2009

Abstract
Sialidase-resistant ganglioside analogs having similar biological activities to natural gangliosides are expected to be important probes for clarifying the biological functions of gangliosides. Focusing on difluoromethylene-linked (CF2
-linked) and methylene-linked (CH2
-linked) α(2,3)sialylgalactose as a core structure of sialidase-resistant ganglioside mimics, we have developed novel, stereocontrolled, and efficient methodologies to synthesize C-sialosides based on Ireland-Claisen rearrangement. These methods were employed to synthesize CF2
-linked GM4. The CF2
-linked GM4 inhibited human sialidases NEU2 and NEU4 with IC50 values of 754 and 930 μM, respectively, and strongly inhibited human lymphocyte proliferation in the same concentration range as natural GM4.
Total synthesis of novel dictyostatin analogs and hybrids as microtubule-stabilizing anticancer agents
Authors: Paterson Ian , Gardner Nicola M. , Naylor Guy J. 
Published: February 2009

Abstract
Structural modification of the dictyostatin macrolide template through adaptation of our total synthesis has led to the identification of a number of potent analogs of this novel microtubule-stabilizing agent. A common synthetic strategy was exploited, employing a (Z)-selective Still-Gennari olefination between various advanced C11-C26 aldehyde and C4-C10 (or C1-C10) β-ketophosphonate intermediates. In vitro evaluation of the growth inhibitory activity of these analogs against both Taxol-sensitive and -resistant human cancer cell lines has provided a foundation for structure-activity relationship (SAR) studies to help define the pharmacophore region.
Dual citizenship rights: do they make more and richer citizens?
Authors: Mazzolari Francesca 
Published: February 2009

AbstractIn the 1990s, Colombia, the Dominican Republic, Ecuador, Costa Rica, and Brazil passed dual citizenship laws granting their expatriates the right to naturalize in the receiving country without losing their nationality of origin. I estimate the effects of these new laws on naturalization rates and labor market outcomes in the United States. Based on data from the 1990 and 2000 U.S. censuses, In find that immigrants recently granted dual nationality rights are more likely to naturalize relative to immigrants from other Latin American countries. They also experience relative employment and earnings gains, together with drops in welfare use, suggesting that dual citizenship rights not only increase the propensity to naturalize but may also promote economic assimilation. The effects of dual citizenship on improved economic performance, if mediated through naturalization, are consistent with American citizenship conferring greater economic opportunities.
Familial and Sporadic Porphyria Cutanea Tarda: Characterization and Diagnostic Strategies
Authors: Aarsand Aasne K , Boman Helge , Sandberg Sverre 
Published: February 2009

Abstract
Background: Porphyria cutanea tarda (PCT) occurs in sporadic (sPCT) and familial (fPCT) forms, which are generally clinically indistinguishable and have traditionally been differentiated by erythrocyte uroporphyrinogen decarboxylase (UROD, EC 4.1.1.37) activity. We used UROD gene sequencing as the reference standard in assessing the diagnostic accuracy of UROD activity, evaluating the mutation spectrum of the UROD gene, determining the frequency and disease attributes of PCT and its subtypes in Norway, and developing diagnostic models that use clinical and laboratory characteristics for differentiating fPCT and sPCT.
Methods: All consecutive patients with PCT diagnosed within a 6-year period were used for incidence calculations. UROD activity analysis, UROD gene sequencing, analysis of hemochromatosis mutations, and registration of clinical and laboratory data were carried out for 253 patients.
Results: Fifty-three percent of the patients had disease-relevant mutations, 74% of which were c.578G&gt;C or c.636+1G&gt;C. The UROD activity at the optimal cutoff had a likelihood ratio (LR) of 9.2 for fPCT, whereas a positive family history had an LR of 19. A logistic regression model indicated that low UROD activity, a high uroporphyrin-heptaporphyrin ratio, a young age at diagnosis, male sex, and low alcohol consumption were predictors of fPCT. The incidence of PCT was 1 in 100 000.
Conclusions: Two commonly occurring mutations are responsible for the high frequency of fPCT in Norway. UROD activity has a high diagnostic accuracy for differentiating the 2 PCT types, and a model that takes into account both clinical information and laboratory test results can be used to predict fPCT.
Formulation of a Guideline for the Determination of Heat Transfer Coefficient during Gas Quenching
Authors: Luebben Thomas , Lohrmann Michael , Segerberg Soeren , Sommer Peter 
Published: February 2009

Abstract
During the past years high pressure gas quenching was a very actual subject at different conferences. There were a lot of lectures which used heat transfer coefficient as the most important parameter for the characterization of a gas quenching system. This statement is surely correct, but only fully utilizable—for example, for the comparison of measurements from different authors—when a well defined measurement method was used. Up to 2002 this was not realized. To solve this problem on a national basis the German Research Committee for Quenching has delt with this subject in the period from 1998 to 2002. In a first step the possibly influencing parameters were identified. In a second step most of the parameters were predefined. In a few cases there was no information about the magnitude of the possible influence available (example: evaluation procedure). To answer these remaining questions a round-robin test was carried out. The participants were the companies Ipsen International and Dr. Sommer Werkstofftechnik, Germany, and the institutes IVF Sweden and IWT Bremen, Germany. The results of this work were published in 2002 in the German heat treatment journal HTM including a recommendation for the measurement of heat transfer coefficient at gas quenching (in German language). This paper is a translation of this work and shall help to solve the above-mentioned problem on an international level.
Analysis of the Belgian Surveillance Fracture Toughness Database Using Conventional and Advanced Master Curve Approaches
Authors: Lucon Enrico , Scibetta Marc , Gérard Robert 
Published: February 2009

Abstract
The “classical” regulatory approach to the analysis of surveillance capsules in nuclear power plants entails an indirect estimate of the fracture toughness of the beltline materials, by inferring rather than measuring their toughness properties. Indeed, the irradiation-induced shift of the fracture toughness curve is assumed to be equal to the shift of the Charpy absorbed energy transition curve at a predefined level (41 J). An alternative surveillance approach, primarily based on direct fracture toughness measurements in the ductile-to-brittle transition region using the Master Curve procedure, has been applied to surveillance materials from several Belgian nuclear power plants in the past 15 years. This has led to the establishment of a significant database, consisting of 292 fracture toughness data points for 23 material conditions (unirradiated materials and surveillance capsules). In this study, different temperature normalization approaches are applied to the available data. The analyses show that data clearly follow the Master Curve formalism. Moreover, it is confirmed that both the static (KIc) and the dynamic (KIR) curves of the ASME Code Section XI provide an effective lower bound to the measured results, although more conservatism is evident when using RTNDT as the normalization parameter. Both the conventional (ASTM E1921-08, ‘‘Standard Test Method for Determination of Reference Temperature, T0, for Ferritic Steels in the Transition Range’’) and advanced (Multi-Modal) Master Curve analyses of the database clearly demonstrate that normalizing data by (T−RTT0) provides the best rationalization of the available information and the most effective representation of the experimental scatter.
GaN Doped with Neodymium by Plasma-Assisted Molecular Beam Epitaxy for Potential Lasing Applications
Authors: Readinger Eric D. , Metcalfe Grace D. , Shen Paul Hongen , Wraback Michael , Jha Naveen , Woodward Nateaniel , Capek Pavel , Dierolf Volkmar 
Published: February 2009

AbstractWe provide an investigation of in situ doping of GaN with the RE element Nd by plasma assisted-molecular beam epitaxy (PA-MBE). GaN epilayers are grown on c-plane sapphire and free standing GaN substrates and the Nd doping is controlled by an effusion cell. The ideal growth conditions for Nd incorporation maintaining crystal quality in GaN were investigated. The optical absorption characteristics indicate that the GaN:Nd epilayer remains transparent at the Nd emission wavelength of interest. For the highest Nd effusion cell temperatures, Rutherford backscattering and secondary ion mass spectrometry data indicate ˜5 at. % in epilayers grown on c-plane sapphire. X-ray diffraction found no evidence of phase segregation up to ˜1 at. % Nd. The highest luminescence intensities correspond to a doping range 0.05-1 at. %, with the strongest emission occurring at 1.12 eV (1107 nm). We also present the Stark energy sublevels of Nd3+ ions in GaN as determined by luminescence spectra. Photoluminescence excitation spectra reveal an optimal excitation energy of 1.48 eV (836 nm). We correlate the photoluminescence spectra with transitions from the 4F3/2 excited state to the 4I9/2, 4I11/2, and 4I13/2 multiplets of the Nd3+ ion for above (325nm) and below (836nm) bandgap excitation. Spectral correlation of the Nd emission multiplets in addition to site-selective spectroscopy studies using combined excitation-emission spectroscopy with confocal microscopy indicate enhanced substantial doping at the Ga site compared to other techniques (ion implantation and co-sputtering).
Spatially Resolved Site Selective Optical Spectroscopy on Nd Doped GaN Epitaxial Layers
Authors: Woodward Nate , Jha Naveen , Readinger Eric , Metcalfe Grace , Wraback Michael , Dierolf Volkmar 
Published: February 2009

AbstractDue to its favorable electronic and thermal properties GaN has been considered as a rare-earth host material for solid state amplifier and laser applications. To this end, we performed spatially resolved combined excitation emission spectroscopy (CEES) on Nd ions which were in-situ-doped into GaN epitaxial films grown by plasma assisted molecular beam epitaxy (PA-MBE) on c-plane sapphire substrate. For a wide range of concentration (up to 8at%) we find in the emission a dominant incorporation site, which can be identified with good certainty as a substitutional ‘Ga’ site. Energy levels and electron-phonon coupling to a localized mode can be identified. For the majority site, confocal spectral imaging under selective excitation show changes in emission intensity, excitation and emission wavelength on a submicron length scale suggesting spatial inhomogeneities in terms of Nd3+ ion concentration.
Studies of III-Nitride Superlattice Structures Implanted with Lanthanide Ions
Authors: Ebdah Mohammad Ahmad , Jadwisienczak Wojciech M , Kordesch Martin E , Ramadan Saleem , Morkoç Hadis , A. Anders A 
Published: February 2009

AbstractCathodoluminescence (CL) of rare earth (RE) ions implanted AlN/GaN superlattice (SL) structures grown by chemical vapor deposition (CVD) technique on GaN/(0001) sapphire substrate was measured at 10 K and 300 K. Implantation of terbium and thulium in SLs was done at 150 keV with a dose of up to 1×1015 cm-2 at 300 K. Samples were given post implantation isochronal thermal treatment at 900 °C in nitrogen ambient. The interface quality between the SL layers before and after implantation as well as after thermal annealing treatment has been investigated by X-ray diffraction (XRD). The characteristic satellite peaks of the SLs were measured for the (0002) reflection in the symmetric Bragg geometry for the reference, RE-implanted, and annealed SLs. Furthermore, the luminescence intensity of a RE3+ ion doped AlN/GaN SL was compared with the one from RE-implanted GaN epilayers. Despite the structural damage of the AlN/GaN structures, an enhancement of the characteristic emission intensities from RE3+ ions in the SLs was observed compared to emission from RE ions in epilayers.
Investigation of the Si-rich silicon oxide by 3D atom probe tomography
Authors: Talbot Etienne , Rodrigue Lardé , Gourbilleau Fabrice , Dufour Christian , Pareige Philippe 
Published: February 2009

AbstractSilicon rich silicon oxide multilayers for optical devices have been investigated by laser assisted wide angle atom probe tomography. Three dimensional mapping of silicon nanoclusters multilayers was obtained. The composition of the different phases were deduced and compared to theoretical concentration. These results evidenced a size distribution of the Si clusters diameter and an incomplete phase separation between silica and silicon particles.
Photoluminescence Activity of Neodymium-Doped Gallium Oxide Thin Films
Authors: Lecerf Celine , Marie Philippe , Frilay Cedric , Cardin Julien , Portier Xavier 
Published: February 2009

AbstractPhotoluminescence activity was observed for neodymium-doped gallium oxide thin films prepared by radiofrequency magnetron co-sputtering. Structural and optical properties of as-grown and annealed films were studied and photoluminescence activity was especially investigated. The most intense lines were associated to the 4F3/2  4I9/2 and 4F3/2  4I11/2 electronic transitions of Nd3+. The effects of deposition and treatment parameters such as the substrate temperature, the post anneal treatment or the neodymium content in the films were particularly examined with the aim to reach the best luminescence efficiency.
Combined Excitation Emission Spectroscopy Studies on Erbium Ions in Stoichiometric Lithium Tantalate
Authors: Woodward Nate , Miyahara Keiko , Toulouse Alex , Capek Pavel , Dierolf Volkmar 
Published: February 2009

AbstractWe present our site-selective spectroscopic studies on Er3+ doped nearly stoichiometric lithium tantalate (LiTaO3) and compare the results with earlier studies performed on the same dopant in the isostructural lithium niobate host. We present our results in terms of the number and spectroscopic characteristics of the incorporation sites. Overall, the sites found in LiTaO3 closely resemble in their behavior the ones found in LiNbO3 such that the conclusion about the nature of the site drawn in the latter host can be transferred to LiTaO3 as well.
Thulium Doped Phosphors Under VUV Excitation
Authors: Moine Bernard , Beauzamy Léna , Meltzer Richard S. 
Published: February 2009

AbstractDevelopment of highly efficient mercury free fluorescent lamps and plasma display panels has been a challenging task due to the need for a combination of phosphor properties that are difficult to obtain in a single material (high efficiency, short emission lifetime and weak sensitivity to aging process under VUV excitation). Quantum cutting mechanism is a way to improve the fluorescence efficacy. Here we describe quantum cutting involving pairs of Tm3+ ions in KY3F10. Efficient excitation in the vacuum UV is initiated to the 5d state of Tm3+. This is followed by a cross relaxation energy transfer (CRET) involving the excited ion in the 5d state and nearby Tm3+ in the ground state, producing a pair of Tm3+ in excited states of the 4f13 configuration. Both ions can then emit photons. The excitation and reflection spectra are studied as a function of Tm3+ concentration and temperature. An unusual enhancement of the reflectivity at excitation wavelengths corresponding to the Tm3+ 5d absorption peaks is shown to arise from strong 5d→4f emission which is confirmed from the VUV emission spectra. The strong reduction of the integrated 5d emission intensity and shortening of its lifetime with Tm3+ concentration indicates the effective presence of the desired CRET process that is required for the first step of the quantum cutting. High Tm3+ concentrations are required for efficient quantum cutting. Whereas the CRET from the 5d state is estimated to be quite efficient, the 4f13 states of Tm3+ also undergo a strong CRET and therefore, emission from the 4f13 excited states that are created from the first step are strongly quenched at high Tm3+ concentrations. As a result, quantum yields greater than unity are not achieved.
Influence of the Evolution of the Surface Area Value on the Spent Nuclear Fuel Dissolution Rate for Performance Assessment Studies
Authors: Quiñones Javier , Iglesias Eduardo , Rodriguez Nieves , Nieto Juan Manuel 
Published: February 2009

AbstractThis paper focuses on how to extrapolate current knowledge of spent fuel matrix alteration processes from laboratory to repository conditions, i.e., the influence of changes in both the initial surface oxidation level and the evolution of the specific surface area during the alteration process. Therefore, a spent fuel matrix alteration model allowing the alteration rate evolution to be predicted as a function of both the host rock considered and evaluation time scale of interest is described. At present, the model assumes that alteration of the spent fuel will start when the groundwater reaches the solid surface and that only the radiolytic species of the groundwater (oxidants generated by a-radiation of spent fuel) will produce the surface oxidation process and subsequent matrix dissolution; O2, H2O2 and OH are the species that react with UO2(s) for oxidation of the pellet surface. The dissolution process of the surface sites that are oxidized is modelled in two steps: first, a surface co-ordination of the oxidized layer with aqueous ligands and, second, detachment (dissolution) of the product species. Taking this mechanism into account, the model gives the evolution of the spent fuel matrix alteration rate over periods as long as 1,000,000 years. In this work is focussed on input the experimental results obtained of UO2 surface area behaviour (presented in previous MRS conference), on the MAM model. The matrix alteration rate results obtained, with MAM model, for repository granitic environment will be presented and compared to those performed for SFS project. Furthermore, a sensitivity analysis study has been performed on the influence of the following variables: Influence of the initial power size distribution and the initial oxidation state
A New Criterion for the Degradation of a Defective Spent Fuel Rod under Dry Storage Conditions Based on Nuclear Ceramic Cracking
Authors: Desgranges Lionel , Charollais François , Felines Isabelle , Ferry Cécile , Radwan Jean 
Published: February 2009

AbstractExperimental results using environmental SEM on intentionally defected fuel particles showed that oxidation induced cracking could lead to the degradation of HTR coated particles. The interpretation proposed for the swelling resulting from cracking can be extended to irradiated nuclear fuels. That is why a new criterion was proposed to defined safe handling of defective fuel in dry storage condition. This criterion defines the time needed to create an oxidized layer thickness leading to significant cracking.
HIPed Tailored Pyrochlore-Rich Glass-Ceramic Waste Forms for the Immobilization of Nuclear Waste
Authors: Carter Melody Lyn , Li Hui , Zhang Yingjie , Gillen Andrew L , Vance Eric R 
Published: February 2009

AbstractHot isostatically pressed (HIPed) glass-ceramics for the immobilization of uranium-rich intermediate-level wastes and Hanford K-basin sludges were designed. These were based on pyrochlore-structured Ca(1-x)U(1+y)Ti2O7in glass, together with minor crystalline phases. Detailed microstructural, diffraction and spectroscopic characterization of selected glass-ceramic samples has been performed, and chemical durability is adequate, as measured by both MCC-1 and PCT-B leach tests.
Identification of Oxygen-Depleting Components in MX-80 Bentonite
Authors: Carlsson Torbjörn , Muurinen Arto 
Published: February 2009

AbstractAfter closure, the near-field of a nuclear waste repository contains large amounts of oxygen in tunnels and deposition holes. The bentonite buffer/backfill will contain oxygen as a gas phase in unsaturated pores as well as dissolved gas in porewater. The redox conditions in the bentonite filling after post-closure will change towards reducing conditions. In the initial stage, the development of the redox state is mainly governed by the depletion of oxygen. The main mechanisms of oxygen depletion in the bentonite are: 1) diffusion into the surrounding rock and 2) reactions with accessory minerals and by microbial aerobic consumption of organic matter [1,2]. The reactions leading to oxygen depletion are not, however, well understood. The objective of this work was to gather new information concerning oxygen depletion in MX-80. This was done by measuring oxygen depletion and changes in the redox state in suspensions of 1) MX-80, 2) a heavy fraction of MX-80, or 3) a light fraction of MX-80.
Soft X-ray Spectroscopic Characterization of Montmorillonite
Authors: Rubensson Jan-Erik , Hennies Franz , Werme Lars O , Karnland Ola 
Published: February 2009

AbstractSoft X-ray spectroscopy was applied to study a calcium bentonite from the Kutch area in India. We recorded the X-ray absorption spectra from the L-edge of calcium, silicon, and aluminum, and from K-edge of oxygen. The Ca absorption spectrum shows a quasi-atomic behavior, while the Si spectrum closely simulates the absorption spectrum of a pure silicon oxide. The O K spectrum shows a pre-peak, which is absent in the spectra of both the pure, bulk aluminum and silicon oxides. The Al L spectrum is complex and shows almost no resemblance to the absorption spectrum of aluminum oxides. The chemical state of the Al atoms (in octahedral coordination) must, thus, be quite different from what is common in the oxides. The obtained data show that soft X-ray spectroscopy is a promising technique for studying clay minerals. It is capable of supplying unique information that is complementary to information accessible using other techniques; especially, it can be used to determine the local electronic structure at various atomic sites in the complex samples.
Experimental Study and Modeling of Uranium (VI) Sorption onto a Spanish Smectite
Authors: Missana Tiziana , Alonso Ursula , Garcia-Gutierrez Miguel , Albarran Nairoby , Lopez Trinidad 
Published: February 2009

AbstractAdsorption of uranium onto a Spanish smectite was studied, analyzing the effects of the most important parameters such as pH, ionic strength, radionuclide concentration and solid to liquid ratio. Batch sorption studies, in anoxic conditions under N2 atmosphere, were carried out on the bentonite previously purified and converted into the homoionic Na-form.
In the sorption edges, two regions could be clearly distinguished. At pH lower than 5, sorption depended strongly on the ionic strength, possibly indicating the predominance of the uranyl ionic exchange process. At higher pH, sorption did not depend on the ionic strength but only on pH. The sorption behavior in this region suggested the predominance of a surface complexation mechanism. Sorption isotherms showed a non linear behavior in the concentration range used.
Sorption data were interpreted using a non electrostatic standard model combining surface complexation, with the weak and strong SOH sites of the clay, and ionic exchange. The acid – base properties of the weak SOH sites were determined by potentiometric titrations. The model used was able to reproduce, in a very satisfactory way, all the data in a wide range of experimental conditions.