bluuebunny/crossref_metadata_2025_split huggingface dataset:
Emergence and present status of Lu-177 in targeted radiotherapy: the Indian scenario
Authors: Banerjee Sharmila , Das Tapas , Chakraborty S. , Venkatesh Meera 
Published: May 2011

Abstract

177Lu is presently considered to be a potential radionuclide for the development of agents for radionuclide therapy owing to its favorable nuclear decay characteristics [T
1/2 = 6.65 d, E

β(max) = 0.497 MeV, E

γ
= 113 KeV (6.4%) and 208 KeV (11%)]. While the long half-life of this promising radioisotope offers distinct logistic advantage, particularly, in countries having limited reactor facilities, the feasibility of its large-scale production with adequate specific activity and excellent radionuclidic purity in medium flux research reactors constitute yet another desirable feature. Extensive studies have been carried out to optimize the production of this isotope, with high specific activity and radionuclidic purity by the (n,γ) route using the highest available flux and the optimum irradiation time. The gradual evolution of clin ical grade 177LuCl3 as a new radiochemical, ready for commercial deployment by Radiopharmaceuticals Division, Bhabha Atomic Research Centre, to nuclear medicine centers all over India was accomplished in 2010 in a stepwise manner with the commencement of the production of high specific activity 177Lu from enriched target in 2001. Research on 177Lu has demonstrated its immense potential in radiotherapeutic applications, a direct outcome of which has resulted in indigenous development of two agents viz.
177Lu-EDTMP and 177Lu-DOTA-TATE presently being evaluated in human patients for palliative care of bone pain due to skeletal metastases and treatment of malignancies of neuroendocrine origin, respectively. Using locally produced 177Lu, the radiolabeling of a plethora of other molecules with potential applicability in radiation synovectomy and targeted therapy of malignant tumors have been successfully demonstrated. A few of these agent such as a novel 177Lu-labeled porphyrin has shown considerable promise in initial studies and is presently evaluated. In the present article, our research efforts toward standardization of production methodology of 177Lu in high specific activity and its utilization in the devel opment of agents for targeted radiotherapy are being reported.
Plasmonics: Electromagnetic Energy Transfer and Switching in Nanoparticle Chain-Arrays Below the Diffraction Limit
Authors: Brongersma Mark L. , Hartman John W. , Atwater Harry H. 
Published: May 2011

ABSTRACTA model is given for the transport of electromagnetic energy through structures that consist of chains of closely spaced metal nanoparticles. This transport relies on the near-field electrodynamic interaction between metal particles that sets up coupled plasmon modes. The model predicts that the propagation is coherent and the group velocities can exceed typical saturation velocities of electrons in semiconductors (≈ 105 m/s). Furthermore, it is shown that in these structures propagation of energy around sharp corners (bending radius << the wavelength of visible light) is possible at high efficiency. This efficiency is a strong function of the frequency and polarization direction of the plasmon mode. The operation of a plasmon switch is modeled, in which plasmon waves can be switched or modulated. Finally, suggestions are given for the choice of metal particle and host material.
Artificial Atoms of Silicon
Authors: Holmes Justin D. , Ziegler Kirk J. , Johnston Keith P. , Doty R. Chris , Korgel Brian A. 
Published: May 2011

ABSTRACTSize-monodisperse, stable 15 Å diameter silicon nanocrystals were synthesized in significant quantities using supercritical octanol as a capping ligand. The silicon nanocrystals exhibit an indirect band gap with discrete electronic transitions in the absorbance and photoluminescence excitation (PLE) spectra. The octanol-capped clusters show efficient blue band-edge photoemission with a luminescence quantum yield of 23 % at room temperature.
From Langmuir-Blodgett Films to Electroluminescent Devices with an Amphiphilic Phenyl-Ethynylene Oligomer
Authors: Arias-Marin E. , Arnault J.C. , Maillou T. , Guillon D. , Moigne J. Le , Geffroy B. , Lorin A. , Nunzi J.M. , Rosilio A. 
Published: May 2011

ABSTRACTNew rigid rods amphiphilic molecules based on phenyl ethynylenes oligomers with hydrophilic side chains were synthesized by step by step method. The two most interesting products, the pentamer and the heptamer are enough amphiphilic to give stable Langmuir films that are able to be deposited as LB film on substrates as hydro-philic glass, ITO or hydrophilic silicon. A good transfer ratio of 1 is observed only by lifting, which suggests a Z type deposited film. A multilayer deposition can be carried out to 36 layers. The well structured films of 3.7 nm thick which are observed by X ray reflectivity suggest a rearragement in Y–type bilayer. By AFM, the observed irregular surface with steps of 3.7 and 1.8 nm high or multiples is coherent with a self-rearrangement of the single deposited layer to a double layer during the drying phase. The heptamer and pentamer show large stokes-shifts with a high photoluminescence emission peak at 516 and 504 nm respectively. LED properties were demonstrated using the ITO/oligoPY/ LiF-Al sandwich yielding photon emission at 516 nm for the heptamer. The electroluminescent device yields in the range of 10−3%. The demonstration of electroluminescence in a LB film of molecules aligned parallel to the substrate is very interesting because it confirms the possibility to tailor conduction and emission properties of the devices using a layer by layer deposition technique.
Photo-Induced Properties of Liquid Crystal Molecules on Alternately Assembled Charged Azobenzene Dyes and Polyelectrolyte Films Using Attenuated Total Reflection Method
Authors: Baba Akira , Kato Takashi , Ishikawa Jun , Kaneko Futao , Shinbo Kazunari , Kato Keizo , Advincula Rigoberto 
Published: May 2011

ABSTRACTIn this report, we describe the photo-induced in-plane alignment of nematic liquid crystal (LC) molecules, 5CB, in a hybrid cell with alternate self-assembled films of low-molecular weight azobenzene dye and polyelectrolyte on gold electrodes using the attenuated total reflection (ATR) measurement method. The molecular self-assembly process was also investigated by the ATR method. Reflectivities due to excitations of the surface plasmon polariton (SPP) were observed in the ATR properties of the LC cell. In-plane switching of the LC molecules adjacent to the aligning layer was evaluated from the ATR curves after irradiation of linearly polarized visible light to the LC cell. The sensitivity of the ATR method gives information on the alignment, tilt angle, and extent of LC reorientation in the bulk. Thus, the importance of using the molecular self-assembly processes of individual polyion-dye pairs for fabrication of new photo-aligning layers is emphasized.
Characterization of Polymer Light Emitting Diodes Fabricated by Ionically Self-Assembled Monolayer Technique
Authors: Marciu D. , Miller M. B. , Heflin J. R. , Murray M. A. , Ritter A. L. , Neyman P. J. , Graupner W. , Wang H. , Gibson H. W. , Davis R. M. 
Published: May 2011

ABSTRACTIonically self-assembled monolayer (ISAM) films are a recently developed class of materials that allows detailed structural and thickness control at the sub-nanometer level combined with ease of manufacturing and low cost. The ISAM fabrication method simply involves the dipping of a charged substrate alternately into polycationic and polyanionic aqueous solutions at room temperatures. Importantly, the ISAM technique yields exceptionally homogeneous, large area films with excellent control of total film thickness. We describe detailed studies of ISAM light emitting diodes incorporating poly(para-phenylene vinylene) (PPV) as the light emitting polymer. The individual thickness of each monolayer and the interpenetration of adjacent layers can be precisely controlled through the parameters of the electrolyte solutions. The effects of the pH and ionic strength of the immersion solutions, the total film thickness, and the PPV thermal conversion parameters on the photoluminescence and electroluminescence yields have been systematically studied. The ISAM process also allows the advantage of depositing well-defined thicknesses of separate polymers at the indium tin oxide and the aluminum electrode interfaces.
Investigation of Photoinduced Charge Transfer in Composites of a Novel Precursor PPV Polymer and Fullerenes
Authors: Brabec Christoph J. , Cravino Antonio , Zerza Gerald , Padinger Franz , Sariciftci N. Serdar , Kiebooms Raphael , Vanderzande Dirk , Hummelen Jan C. 
Published: May 2011

ABSTRACTHomogenous blends of a processable methanofullerene, [6,6]-Phenyl C61 - butyric acid methyl ester (PCBM), with poly (p-phenylene vinylene) (PPV) made from a novel nonionic precursor route were investigated by optical spectroscopy and by photocurrent measurements. The conversion process of the precursor polymer to the PPV in the blends with PCBM was monitored by IR absorption. In composites of PPV/PCBM strong quenching of the PPV luminescence was observed. LESR (light induced electron spin resonance) and PIA (photoinduced absorption) studies confirmed the occurrence of photoinduced electron transfer from the PPV to PCBM. Photovoltaic devices made from PPV/PCBM blends showed monochromatic power conversion efficiencies of app. 0.3%. The spectral photocurrent was observed to follow the absorption profile of the PPV.
Highly Ordered Crystalline Thin Film Bilayers of Para-Hexaphenyl and C60 Grown by Hot Wall Epitaxy
Authors: Sitter Helmut , Matt Gebhard , Andreev Andrei Yu. , Brabec Christoph J. , Badt Dirk , Neugebauer Helmut , Sariciftci Niyazi S. 
Published: May 2011

ABSTRACTThis work focuses on single - and bilayers of para - hexaphenyl (PHP) and C60 grown by Hot Wall Epitaxy. A detailed study of the growth process was performed on glass, ITO and (001)- oriented cleaved mica substrates. The ordering of the layers was investigated by X-ray diffraction, showing clear diffraction peaks for layers grown on mica. The PHP layers grown on mica show high optical anisotropy (dichroic ratios up to 14 in emission) according to the polarization dependent photoluminescence experiments. The highly ordered structure is also reflected in the surface morphology of the layer as observed by atomic force microscopy. The epitaxial growth on mica is mirrored by the main alignment of the surface structure to the orientation of the mica substrate.
Synthesis and Characterization of New Polyaryleneethynylenes based on 3-Hexyl Multisubstituted Oligothiophene Blocks
Authors: Destri Silvia , Porzio William , Khotina Irina A. , Botta Chiara , Consonni Roberto 
Published: May 2011

ABSTRACTA series of new regioregular polyaryleneethynylene obtained by condensation of 3-hexyl multisubstituted oligothiophene derivatives with benzene and anthracene compounds were prepared. A complete NMR characterization of the starting monomers and model compounds lead to a deep investigation of the corresponding macromolecules. Both small and large molecules were optically characterized, the former, particularly when containing anthracene, moieties display noticeable photoluminescence quantum yield. In the polymers the photoluminescence quantum yield is lower than that of the starting molecules when anthracene is present, while the polymers containing benzene are more luminescent.
Luminescence Dynamics of Alq3-Based Multilayer Structures in Terms of HOMO and LUMO Energy Discontinuity
Authors: Fujita Shizuo , Nakazawa Tadahiro , Asano Mitsuru , Fujita Shigeo 
Published: May 2011

ABSTRACTOptical properties of organic multilayer structures with type-I and type-II energy lineups with respect to the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy levels were investigated and compared. The fast energy transfer followed by carrier confinement in the material with lower HOMO-LUMO energy difference was proved for the structures with type-I energy lineup, while the tendency of separation of excited states, i.e., electrons and holes generated in the excited molecules, was demonstrated for those with type-II. These results indicate that the luminescence dynamics of organic multilayer structures are well discussed in terms of HOMO and LUMO energy lineups similarly to valence and conduction band energies in inorganic semiconductors.
Synthesis and Application of Chiral Conjugated Polymers and Dendrimers
Authors: Pu Lin 
Published: May 2011

ABSTRACT1,1'-Binaphthyl-based chiral polymers and dendrimers have been synthesized and their potential applications have been explored. These materials have shown a variety of interesting properties such as electroluminescence, optical nonlinearity, enantioselective catalysis and chiral sensing.
Requirements on Organic Electro-Optic Devices for Aerospace Applications
Authors: Anderson W. W. , Ermer S. P. , Eck T. E. Van , Girton D. G. , Taylor R. E. 
Published: May 2011

ABSTRACTTerrestrial digital photonic technology development will not satisfy all of the aerospace requirements since RF links are often required. Organic electro-optic devices are readily adaptable to RF functions into the 100 GHz and above frequency range. In addition to lossless links, they can be utilized for RF signal processing functions such as mixing, efficient harmonic generation and filtering. Devices can be densely packed with negligible cross talk.In addition to the well known survivability requirements for space born applications (lifetime, reliability, thermal, shock, vibration and radiation hardness), issues of weight and power become dominant. Organic devices based on thin film technologies have an obvious potential advantage with respect to weight. However, integration with other optical and/or electronic components needs to be considered since connectors often dominated size and weight. Performance (when translated back into the electronic domain) scales as the optical power and device sensitivity squared. Thus, advances in device sensitivity can be nullified by increases in optical loss.
Experimental Study and Modeling of the Radium Sorption onto Goethite
Authors: Bassot Sylvain , Mallet Caroline , Stammose Denise 
Published: May 2011

ABSTRACTIron oxyhydroxides play a significant role in radium behavior in uranium mill tailings. Although they are present at trace level (less than 1% in mass), iron oxyhydroxides are responsible of the retention of significant amounts of radium in these residues. A part of these oxyhydroxides is present as amorphous or ill-crystallized forms, the other part corresponds to crystalline iron oxyhydroxides like goethite.In this paper, we present data concerning radium sorption on a well-characterized goethite (α-FeOOH). Batch experiments have been performed and the influence of different parameters such as contact time, pH and electrolyte concentration of the solution has been examined. The sorption equilibrium was obtained after a contact time of 1 hour. In sodium perchlorate medium, the amount of sorbed radium reaches a maximum for pH higher than 8 and no significant influence of sodium concentration was observed. However, the calcium concentration greatly influences the radium sorption: the greater the calcium concentration, the less radium is sorbed. The kinetics of the radium desorption are slower than those of sorption: more than 30% of radium remains sorbed on goethite after 1 week of contact time.Using the characteristics of the goethite surface (total number of sites, intrinsic acidity constants, intrinsic constants of calcium), modelling of the experimental data with inner sphere complexes gave satisfactory results. Two surface species involving radium can be formed (SORa+ and SORaOH). These sorption constants determined allow prediction of the radium sorption onto goethite in the chemical conditions of uranium mill tailings.
Pretreat: A Graphical User Interface-Based Spreadsheet Model for Hanford Tank Waste Pretreatment Processes
Authors: Yang Lietai , Pabalan Roberto , Jain Vijay 
Published: May 2011

ABSTRACTA spreadsheet model, PRETREAT, was developed for mass-balance calculations of pretreatment processes proposed for the immobilization of Hanford nuclear wastes. In PRETREAT, a graphical user interface is implemented for convenient navigation through the large number of worksheets used in the model, for data input, modification of process parameters, and viewing model results. PRETREAT can be used to estimate radionuclide and chemical species concentrations in the waste streams at each stage of the pretreatment flowsheet, and to help in assessments of potential radiological, chemical, and criticality hazards and in identification of mitigation strategies. The model can also be used to evaluate the sensitivity of model results to uncertainties in model parameters such as decontamination or separation factors.
Studies of sorption of Th and Np on UO2 and TiO2
Authors: Albinsson Yngve , Nilsson Hans , Jakobsson Anna-Maria 
Published: May 2011

ABSTRACTWhen designing an underground repository for spent nuclear fuel it is important to know if and to what extent Np and Pu are reduced. At the moment only Np has been studied, but further investigations with Pu are planned.Np in the pentavalent state and Th in the tetravalent state (234Th, about 10−9 M) have been used to study the sorption onto TiO2 (no reduction is expected) and onto UO2 with different atmospheres (air, nitrogen and nitrogen and hydrogen at 5 MPa pressure), and with different Np- concentrations (about 10−12M, 239Np and 10−6 M,237Np).Th is sorbed to a high extent at pH>3 on both TiO2 and UO2. The sorption increases 3 orders of magnitude over one pH-unit when log Ka (the distribution coefficient with respect to surface area) is plotted against pH.The Np sorption on TiO2 is independent of the Np concentration and shows a slope of one when pH is plotted against log Ka. The higher sorption of Np onto UO2 compared with TiO2 indicates that Np is partially reduced even when it is in contact with air. No large differences can be observed for Np between the nitrogen and hydrogen-atmosphere, indicating that the absence of oxygen is the important factor for the reduction. The different Np concentrations had no great impact on the reduction/sorption on UO2.
Evidence of Heterogeneous Matrix Diffusion in Fractured Crystalline Rock in Laboratory Migration Experiments
Authors: Xu Shulan , Wörman Anders 
Published: May 2011

ABSTRACTThe geostatistics of the main properties of transport in crystalline rock at Äspö Hard Rock Laboratory, Sweden have been determined experimentally, using a large number of samples, as a basis for the analysis of the effect of the uncertainty in rock heterogeneity on radionuclide migration in a single fracture. The auto-covariance functions were estimated for the porosity, effective diffusivity and adsorption characteristics, such as partition coefficient, kdand adsorption kinetics. The one-dimensional analytical solutions for the mean values of the temporal moments of the residence time probability density function (PDF) were derived by using the spectral method. The solutions were applied to the evaluation of migration experiments on granitic drill cores from the Äspö Hard Rock Laboratory. Fractures were created in drill cores by sawing and tritium was used as a non-sorbing tracer in several experiments in each drill core. By systematically varying the flow velocity, u, we could verify the non-linear influence of 1/u on the variance of the residence time PDF according to the theory. The effect of the uncertainty in the heterogeneous rock properties on the solute transport observed in the migration experiments corresponds fairly well to the theoretical effect using the auto-covariance functions.
Experimental Study of Nickel Solubility in Sulfidic Groundwater under Anoxic Conditions
Authors: Carlsson T. , Vuorinen U. , Kekki T. , Aalto H. 
Published: May 2011

ABSTRACTThis paper presents the results from an experimental study of the nickel solubility in sulfidic groundwater under anoxic conditions. The waters used were natural groundwater from Olkiluoto and synthetic saline groundwater, to which sulfide had been added. Two sulfide concentrations, 3.1.10−6 M and 9.4.10−5 M, were used. The possible influence of ferrous iron on the nickel concentration was also studied by adding small amounts of iron chloride, which yielded ferrous iron concentrations of 1.8.10−5 M or less.The initial nickel concentrations in the water samples were 1.0.10−6 M and 1.0.10−3 M. The nickel concentrations were determined using 63Ni and liquid scintillation counting. The duration of the experiments was 177 days.The results for the waters differed markedly. The nickel concentration in the natural groundwater decreased in all samples to roughly 10% of the initial value.The nickel concentration in the synthetic groundwater was found to decrease in those samples having initial sulfide and nickel concentrations of 9.4.10−5 M and 1.0.10−6 M, respectively. The nickel concentration was in this case reduced to about 1% of its initial value. For the other synthetic groundwater samples, the nickel concentration remained at its original initial level.The variation of the ferrous iron concentration did not have any observable effect on the measured nickel concentrations.
Development of Zirconolite-based Glass-Ceramics for the Conditioning of Actinides
Authors: Loiseau P. , Caurant D. , Baffier N. , Mazerolles L. , Fillet C. 
Published: May 2011

ABSTRACTZirconolite (CaZrTi2O7) based glass-ceramics designed for the specific immobilization of plutonium wastes or minor actinides (Np, Am, Cm) from high level radioactive wastes were investigated. To reach an efficient double containment, actinides must be preferentially located in the crystalline phase, which is homogeneously dispersed in a calcium aluminosilicate residual glass. Several heat treatments (between 950° and 1350°C) of a parent glass belonging to the SiO2-Al2O3-CaO system and containing TiO2 and ZrO2 were performed to prepare glass-ceramics. Trivalent minor actinides were simulated introducing Nd2O3 in the glass composition. Electron microscopy, X-ray diffraction (XRD) and thermal analysis have shown that devitrification processes in the bulk and on glass surface are different. They lead to the crystallization of zirconolite in the bulk and to a mixture of titanite (CaTiSiO5) and anorthite (CaAl2Si2O8) near the surface. For heat treatment temperatures greater than or equal to 1250°C, baddeleyite (m-ZrO2) crystals form at the expense of zirconolite in the bulk of glass-ceramics. XRD indicates that the order in zirconolite Ca/Zr planes increases with heating temperature. At the same time, extended defects density decreases.