bluuebunny/crossref_metadata_2025 huggingface dataset:
Culture and assessment of manic symptoms
Authors: Mackin Paul , Targum Steven D. , Kalali Amir , Rom Dror , Young Allan H.
Published: November 2006

Cultural background may influence the perception of psychiatric symptoms. We examined the effects of cultural biases on the identification of manic symptoms using the Young Mania Rating Scale. Two video interviews, each with an American person with mania, were shown to psychiatrists from three countries (US, UK and India). Total scores on the scale differed significantly between the US and UK (P < 0.001) and between India and UK (P < 0.001) rater groups. Overall, differences between India and US rater groups were less marked (P=0.28). These differences suggest that cultural biases influence the interpretation of manic symptoms.
Costs and consequences of enhanced primary care for depression
Authors: Gilbody Simon , Bower Peter , Whitty Paula
Published: November 2006

Background

A number of enhancement strategies have been proposed to improve the quality and outcome of care for depression in primary care settings. Decision-makers are likely to need to know whether these interventions are cost-effective in routine primary care settings.

Method

We conducted a systematic review of all full economicevaluations (cost-effectiveness and cost-utility analyses) accompanying randomised controlled trials of enhanced primary care for depression. Costs were standardised to UK pounds/US dollars and incremental cost-effectiveness ratios (ICERs) were visually summarised using a permutation matrix.

Results

We identified 11 full economic evaluations (4757 patients). A near-uniform finding was that the interventions based upon collaborative care/case management resulted in improved outcomes but were also associated with greater costs. When considering primary care depression treatment costs alone, ICER estimates ranged from £7 ($13, no confidence interval given) to £13 ($24, 95% CI—105 to 148) per additional depression-free day. Educational interventions alone were associated with increased cost and no clinical benefit.

Conclusions

Improved outcomes through depression management programmes using a collaborative care/case management approach can be expected, but are associated with increased cost and will require investment.
Dose escalation for insufficient response to standard-dose selective serotonin reuptake inhibitors in major depressive disorder
Authors: Ruhé Henricus G. , Huyser Jochanan , Swinkels Jan A. , Schene Aart H.
Published: November 2006

Background

Although selective serotonin reuptake inhibitors (SSRIs) are frequently used for major depressive disorder, only 50–60% of patients respond to a standard dose. For non-responders, dose escalation is often applied.

Aim

To systematically review the evidence for dose escalation of SSRIs.

Method

A systematic literature search in MEDLINE, EMBASE, CINAHL and PsycInfo was performed. Randomised controlled trials and meta-analyses investigating dose escalation of SSRIs were identified. Relevant articles were retrieved and critically appraised. Results were summarised in an evidence table. Pooling was not justified because of heterogeneity of the identified studies.

Results

Eight true dose-escalation studies and three meta-analyses were identified. The available data provided no unequivocal base for dose escalation. Dose escalation before 4 weeks of treatment at a standard dose appeared to be ineffective.

Conclusions

Dose escalation of SSRIs is equivocally supported by evidence of randomised controlled trials; methodological difficulties in the studies may account for this lack of evidence.
Prion diseases in humans: an update
Authors: Butler Rob
Published: November 2006

The year 2006 marks 20 years from the first identified bovine spongiform encephalitis in cows and 10 years from the first description of variant Creutzfeldt-Jakob disease in humans. The threatened epidemic in humans now appears unlikely, but psychiatrists need to be aware of recent developments in prion diseases.
Lebanon's Contemporary Significance
Authors: Nedzi Lucien N.
Published: November 2006

Lucien N. Nedzi is a former member of Congress who served from 1961 to 1981 and a member of the editorial advisory board of Mediterranean Quarterly. His service in the US House of Representatives included membership in the Armed Services Committee and the chairmanship of the first Select Committee on Intelligence.
Relations among Turkey, Iraq, Kurdistan-Iraq, the Wider Middle East, and Iran
Authors: Olson Robert
Published: November 2006

Robert Olson is professor of Middle East Politics at the University of Kentucky.
Turkey and Israel's Relationship in the Middle East
Authors: Walker Joshua
Published: November 2006

Joshua Walker is a doctoral candidate at Princeton University's Woodrow Wilson School and a former Fulbright Fellow in Ankara, Turkey.
FoxD3 regulation of Nodal in the Spemann organizer is essential forXenopusdorsal mesoderm development
Authors: Steiner Aaron B. , Engleka Mark J. , Lu Qun , Piwarzyk Eileen C. , Yaklichkin Sergey , Lefebvre Julie L. , Walters James W. , Pineda-Salgado Liliam , Labosky Patricia A. , Kessler Daniel S.
Published: November 2006

Induction and patterning of the mesodermal germ layer is a key early step of vertebrate embryogenesis. We report that FoxD3 function in the Xenopus gastrula is essential for dorsal mesodermal development and for Nodal expression in the Spemann organizer. In embryos and explants, FoxD3 induced mesodermal genes, convergent extension movements and differentiation of axial tissues. Engrailed-FoxD3, but not VP16-FoxD3, was identical to native FoxD3 in mesoderm-inducing activity, indicating that FoxD3 functions as a transcriptional repressor to induce mesoderm. Antagonism of FoxD3 with VP16-FoxD3 or morpholino-knockdown of FoxD3 protein resulted in a complete block to axis formation, a loss of mesodermal gene expression, and an absence of axial mesoderm, indicating that transcriptional repression by FoxD3 is required for mesodermal development. FoxD3 induced mesoderm in a non-cell-autonomous manner, indicating a role for secreted inducing factors in the response to FoxD3. Consistent with this mechanism, FoxD3 was necessary and sufficient for the expression of multiple Nodal-related genes, and inhibitors of Nodal signaling blocked mesoderm induction by FoxD3. Therefore,FoxD3 is required for Nodal expression in the Spemann organizer and this function is essential for dorsal mesoderm formation.
Sperm plasma membrane breakdown during Drosophila fertilization requires Sneaky, an acrosomal membrane protein
Authors: Wilson Kathleen L. , Fitch Karen R. , Bafus Blaine T. , Wakimoto Barbara T.
Published: November 2006

Fertilization typically involves membrane fusion between sperm and eggs. In Drosophila, however, sperm enter eggs with membranes intact. Consequently, sperm plasma membrane breakdown (PMBD) and subsequent events of sperm activation occur in the egg cytoplasm. We previously proposed that mutations in the sneaky (snky) gene result in male sterility due to failure in PMBD. Here we support this proposal by demonstrating persistence of a plasma membrane protein around the head of snkysperm after entry into the egg. We further show that snky is expressed in testes and encodes a predicted integral membrane protein with multiple transmembrane domains, a DC-STAMP-like domain, and a variant RING finger. Using a transgene that expresses an active Snky-Green fluorescent protein fusion (Snky-GFP), we show that the protein is localized to the acrosome, a membrane-bound vesicle located at the apical tip of sperm. Snky-GFP also allowed us to follow the fate of the protein and the acrosome during fertilization. In many animals, the acrosome is a secretory vesicle with exocytosis essential for sperm penetration through the egg coats. Surprisingly, we find that the Drosophila acrosome is a paternally inherited structure. We provide evidence that the acrosome induces changes in sperm plasma membrane, exclusive of exocytosis and through the action of the acrosomal membrane protein Snky. Existence of testis-expressed Snky-like genes in many animals, including humans, suggests conserved protein function. We relate the characteristics of Drosophila Snky, acrosome function and sperm PMBD to membrane fusion events that occur in other systems.
Functional Design of Ionic Liquids
Authors: Ohno Hiroyuki
Published: November 2006

Ionic liquids, molten salts at temperatures lower than 100 °C, preferably below room temperature, are unique liquids having very different characteristics from ordinary molecular liquids. Since these ionic liquids are prepared by coupling relatively large organic ions, there are many chances to create novel functionalities by changing structure of component ions. To develop such novel and functional ionic liquids, we first developed a facile preparation method, i.e., neutralization of tertiary amines with organic acids. By this convenient method, we prepared hundreds of salts having low melting points. We, then, tried to prepare ionic salts containing small ions such as lithium cation, proton, or chloride anion. Because small ions received stronger electrostatic force due to higher surface charge density, which results in the formation of salts with higher melting points, case must be taken. Ionic liquids containing halogen-free salts are another interesting subject to challenge from the viewpoint of environmentally friendly materials. Heteroaromatic rings such as azolates gave excellent ionic liquids having very low viscosity by coupling with suitable cations. Amino acids have also been used as anions to prepare salts with low melting points or amorphous glasses. They are helpful to analyze the relationship between ion structure and characteristics of the salts. Zwitterions, in which both cation and anion were tethered with a covalent bond, were prepared to function as ionic liquids. These ions should not migrate under a potential gradient and should be an excellent ion conductive matrix for added ions. Tethering of ions caused the Tm to be high, and the zwitterions with melting points around room temperature have not been synthesized yet. However, lots of solid zwitterions became liquids by adding suitable solid salts or acid such as lithium bis(trifluoromethanesulfonyl)imide. In this mixture, lithium cations had a transport number higher than 0.5, meaning that the lithium cations are the major mobile ions in the mixture. Some of the functionality is achieved by dimension control, such as polymerization of ions, and so on. Other functional modifications and design of ionic liquids are also mentioned.
Ultrasonic and Viscometric Studies of Molecular Interactions in Binary Mixtures of Acetonitrile with Some Amides at Different Temperatures
Authors: Nain Anil Kumar
Published: November 2006

Ultrasonic speeds (u) and viscosities (η) of binary mixtures of acetonitrile (ACN) with formamide (FA), N,N-dimethylformamide (DMF), N-methylacetamide (NMA), and N,N-dimethylacetamide (DMA), including those of pure liquids, over the entire composition range expressed by mole fraction x1 of ACN (0 ≤ x1 ≤ 1) were measured at 293.15, 298.15, 303.15, 308.15, 313.15, and 318.15 K. From the experimental data, the deviations in isentropic compressibility (Δks), in ultrasonic speed (Δu), and in viscosity (Δη), and partial molar compressibilities, ( and ) for ACN in amide and amide in ACN at infinite dilution, respectively, were calculated. The variation of these parameters with composition and temperature of the mixtures are discussed in terms of the molecular interactions in these mixtures. It was observed that the ACN–amide interaction in these mixtures follows the order: FA > NMA > DMA > DMF. The effect of the number and position of the methyl group on the amide on the molecular interactions in these mixtures is also discussed. Finally, the free energy (ΔG*), enthalpies (ΔH*), and entropies (ΔS*) of activation of viscous flow have also been obtained by using Eyring’s viscosity equation, and the dependence of ΔG*, ΔH*, and ΔS* on composition of the mixtures is also discussed.
Chemically Driven Tension Fluctuation and Motion of Interface with Divalent Cation and Di(2-ethylhexyl)phosphoric Acid
Authors: Shioi Akihisa , Yamada Kanako , Shiota Runa , Hase Fumie , Ban Takahiko
Published: November 2006

Fluctuation in the interfacial tension in an oil/water interface composed of di(2-ethylhexyl)phosphoric acid (DEHPA) and divalent cations (Mg2+, Ca2+, Sr2+, and Ba2+) were investigated. Only a combination of Ca2+ and DEHPA caused noticeable tension fluctuation and spontaneous interfacial flow. Light-scattering experiments and the extraction of cations with DEHPA indicated that both a high reactivity between cation and DEHPA, of which only Ca2+ had a high reactivity, and strong attractive interactions between M(DEHP)2 molecules were required for fluctuation. These may induce a collective desorption of Ca(DEHP)2. This was supported by the observation of alternating pH-change with m-Cresol Purple. An N-shape dependency of interfacial pressure on the DEHPA concentration was observed only for Ca-containing interface. Due to this dependency, there was a DEHPA concentration range in the interfacial pressure vs the concentration curve, which satisfies two different conditions. First, the dependency of the interfacial pressure on the concentration is negative, and second, there are other two concentrations with the same interfacial pressure value. The DEHPA concentration range involving tension fluctuation almost agreed with the concentration range, which is discussed. The interface may be a chemical generator predicted by Vedove and Sanfeld.
Adsorption-Equilibrium Surface Tension of Surfactant Solutions; Examination by the Drop Volume Method
Authors: Matsuki Hitoshi , Yamanaka Michio , Yamashita Yuji , Kaneshina Shoji
Published: November 2006

The surface tension of aqueous solutions of cationic, nonionic, and anionic surfactants was measured as a function of the size of drop formed under the tip of a glass capillary and the time for which the drop is allowed to stand by a previously developed apparatus based on the drop volume method. The surface tension of cationic and nonionic surfactant solutions was slightly dependent on the drop size and the adsorption time at low concentrations, and we could easily obtain the adsorption-equilibrium surface tension values by use of an intact capillary. However, the surface tension of anionic surfactant solutions showed a strong dependence on these factors, and the equilibrium surface tension values could not be obtained by use of the intact capillary at all. This situation was drastically improved by use of the water-repellent capillary coated with a silane-coupling reagent. We proposed that the equilibrium surface tension value of surfactant solutions can be determined by adopting the adsorption time at which the surface tension value becomes constant on the surface tension vs the drop size curves. Further, the conditions under which the equilibrium surface tension value of surfactant solutions could be acquired by means of the drop volume method were quite different than those of the Wilhelmy plate method.
Flux Growth and Characterization of Photocatalytic Na2Ti6O13 Whiskers
Authors: Teshima Katsuya , Yubuta Kunio , Sugiura Shiori , Suzuki Takaomi , Shishido Toetsu , Oishi Shuji
Published: November 2006

High quality, hexagonal prismatic Na2Ti6O13 whiskers were easily grown by the slow-cooling of a NaCl flux. Whisker growth was conducted by heating a mixture of solute (Na2CO3 + TiO2) and flux (NaCl) at 1100 °C and held at this temperature for 10 h, and then the mixture was cooled at a rate of 5 °C h−1 to 500 °C. The Na2Ti6O13 whiskers had average lengths of up to 100 μm and widths of up to 2.0 μm and were transparent and colorless. The whiskers were hexagonal prisms bounded by well-developed {010}, {100}, {001}, and {} faces. The whiskers exhibited good photocatalytic activity under UV light irradiation. Sodium chloride was found to be a very suitable flux for environmental friendly growth of photocatalytic whiskers.
Syntheses, Structures, and O2-Reactivities of Copper(I) Complexes with Bis(2-pyridylmethyl)amine and Bis(2-quinolylmethyl)amine Tridentate Ligands
Authors: Kunishita Atsushi , Osako Takao , Tachi Yoshimitsu , Teraoka Junji , Itoh Shinobu
Published: November 2006

The structure and O2-reactivity of the copper(I) complexes supported by bis[(6-phenyl-2-pyridyl)methyl]amine tridentate ligands (L5R) and bis(2-quinolylmethyl)amine tridentate ligands (L6R) have been investigated in detail in order to get insights into the steric effects of the tridentate ligands on copper(I)/O2 chemistry. In the cases of benzyl amine and phenethyl amine derivatives [R = –CH2Ph (Bz) and –CH2CH2Ph (Phe)], the reaction between the ligands and [CuI(CH3CN)4]+ gave the corresponding copper(I)–acetonitrile complexes having a distorted tetrahedral geometry. On the other hand, the 2,2-diphenylethyl amine derivative L6R [R = –CH2CHPh2 (PhePh)] afforded a copper(I) complex without an ancillary ligand (CH3CN) and having intramolecular d–π interaction between the copper(I) ion and the phenyl group of the alkyl substituent PhePh. The acetonitrile complexes were then converted to the corresponding CO-complexes by reacting with CO gas. The X-ray structures of all CO-complexes have been determined, and the complexes have a similar distorted tetrahedral geometry. In addition, the 6-phenyl group of L5R imparts a large steric effect on the metal-binding. The CO-complexes were converted to the copper(I) complexes without having any ancillary ligands in order to examine their O2-reactivity. Significantly large differences in O2-reactivity were found among the copper(I) complexes. On the basis of O2-reactivity together with the X-ray structures and the oxidation potentials of the copper(I) complexes, the steric effects of the hetero-aromatic donor groups (6-substituted pyridine and quinoline) as well as the alkyl substituents (R) are discussed in detail.
Sulfur-Bridged Dinuclear and Tetranuclear Complexes Consisting of cis-[Ru(bpy)2]2+ and cis-[Ni(aet)2] Units
Authors: Yoshimura Takashi , Shinohara Atsushi , Hirotsu Masakazu , Ueno Keiji , Konno Takumi
Published: November 2006

The 1:1 reaction of [Ru(bpy)2(solvent)2]2+ (bpy = 2,2′-bipyridine) with [Ni(aet)2] (aet = 2-aminoethanethiolate) gave a S-bridged RuII2NiII2 tetranuclear complex with an eight-membered Ru2Ni2S4 metallacycle, [{Ru(bpy)2}2{Ni(aet)2}2]4+, while a S-bridged RuIINiII dinuclear complex with a four-membered RuNiS2 metallacycle, [Ru(bpy)2{Ni(aet)2}]2+, was obtained by the corresponding 1:2 reaction between [Ru(bpy)2(solvent)2]2+ and [Ni(aet)2].
Formation of 2,2′-Diacyl-9,9′-bifluorenylidene Isomers from 2-Acyl-9-bromofluorene and Base-Catalyzed Isomerization of the Formed Alkenes
Authors: Minabe Masahiro , Yamazaki Ayumi , Imai Toshinobu , Takanezawa Takumi , Karikomi Michinori
Published: November 2006

We studied the formation of 2,2′-diacyl-9,9′-bifluorenylidene from 2-acyl-9-bromofluorene. The E-isomer was obtained mainly when the acyl group was a short alkyl chain, such as an acetyl group, and Z-isomer was isolated predominantly when a long acyl chain such as stearoyl group was attached. 9,9′-Bifluorenylidene was formed via anti elimination of hydrogen bromide from the intermediate 9-bromo-9,9′-bifluorenyl. This indicated that the stereochemistry of 2,2′-diacyl-9,9′-bifluorenylidene was determined by the configuration of 9-bromo-9,9′-bifluorenyl isomers, giving Z- and E-isomers in a ratio of 1:1. Facile base-catalyzed Z/E isomerization of 9,9′-bifluorenylidenes followed the formation of the alkenes, which showed different stereoselectivity depending upon the length of the acyl side-chain. On the other hand, thermal treatment of 2,2′-diacyl-9,9′-bifluorenylidene afforded a ca. 1:1 mixture of Z- and E-isomers, suggesting that thermal isomerization took place through a different pathway than base-catalyzed isomerization.
Tests on Unbonded Post-Tensioned Concrete Flat Plate with T-shaped Column Connections
Authors: Cai Jian , Li Guangxing , Yang Chun , Lin Fan
Published: November 2006

Experiments on six full-scale concrete flat plates with T-shaped column connections subjected to discrete gravity loads are reported. One of the slab specimens had ordinary bonded reinforcement only, while the remaining five were post-tensioned by unbonded tendons with various effective prestressing stresses. The effects of other parameters such as slab thickness and top flexural reinforcement ratio were also investigated. All specimens were loaded to failure, so that failure modes and the ultimate load capacity of the connections were obtained. The strain characteristics of reinforcement and the development of the stresses in the unbonded tendons during testing were recorded.

All experimental results showed a combined failure mode, but the flexural failure mode of the slab dominated in all specimens. At final stages, punching shear failure surfaces emerged in the slabs suddenly adjacent to the T-shaped columns. Such a failure surface was local and not continuous around the column as is the case for a square column connection. The test results showed that the prestressed concrete specimens keep significant ductility and have a higher resistance to punching shear failure. In general, the punching shear resistance of the slabs increased with increase in the prestressing force. The punching shear strength test results were compared with the practical predictions stated in worldwide codes such as ACI 318–02, Eurocode 2 and GB 50010. Because of the conservative approaches adopted in these codes, the calculated load capacities of the slabs are significantly underestimated when taking into account the effect of shear reinforcement. However, in good agreement the whole concrete capacity is taken into account, the experimental loads and calculated loads were achieved when the shear reinforcement was ignored. It is recommended that the formulae proposed by the three codes are suitable for adaptation for practical connection design.
Modeling Analytical Moment-Rotation Curves of Semi-Rigid Connections for CFT Square Columns and Steel Beams
Authors: Choi S. M. , Hong S. D. , Kim Y. S.
Published: November 2006

In a structural analysis for building frames, beam-to-column connections are assumed generally as a rigid and/or pinned condition for analysis simplicity. It gives some discrepancy for an overall behavior of building frames having some rotational rigidity in all connections. Many researchers have been interested in, and studied, structural behavior for building frames with semi-rigid connections. Despite many structural merits of concrete filled steel tubular (CFT) columns, such merits are not very clear for exact structural behavior between CFT columns and steel beams. This article is focused on a moment-rotation relationship for CFT frames composed of beam-column connections of exterior diaphragm with four rectangular plates. It is known from previous experimental results that CFT frames with exterior diaphragm connections have been represented as a semi-rigid condition, with a low stiffness due to out-of-plane deformations of square tubes. The main purpose of this study is to get a function formula of the moment-rotation curve for the connections. There are not sufficient test results of the connections to get a function. Therefore, an analytical approach needs to be utilized using a finite element program, ANSYS. The analysis models are made from existing test specimens and additional models are made for the implementation of insufficient test results. The function of a moment-rotation curve is proposed, using a three-parameter power model and a least-mean-square technique. The initial rotational stiffness of beam-to-column connection is determined by slope from zero to the analytical results.
Modeling the Amount of Steel Corrosion at the Cracking of Concrete Cover
Authors: Zhao Y. X. , Jin W. L.
Published: November 2006

This article tries to contribute to quantify the amount of steel corrosion at the cracking of concrete cover. The amount of steel corrosion when the concrete cover cracks, is a key factor in the life of concrete structures. During the time between steel depassivation and concrete cover cracking, the process of steel corrosion develops in three stages: free expansion of the corrosion products, stress initiation of the concrete cover, and cracking of the concrete cover. A concrete cracking model is presented here to estimate the total amount of steel corrosion at the onset of the cracking of the concrete cover. This model is applied to some test results reported by other researchers. The amount of steel corrosion predicted by the proposed model when cracking of the concrete cover occurs is in agreement with the experimentally observed results.
Debonding Mechanisms in FRP Plated Unreinforced Masonry under Out-Of-Plane Loading
Authors: Xia Shaohua , Oehlers Deric
Published: November 2006

Of major concern is the out of plane strength of unreinforced masonry (URM) structures subjected to seismic loads. Through tests and numerical simulations, this article shows that the application of externally bonded (EB) fibre reinforced polymer (FRP) plates to URM members can substantially increase the out of plane strength. Of fundamental importance to the behaviour of EB FRP plated masonry is the plate debonding mechanism as this affects not only the ultimate strength but also the ability to absorb energy. A numerical procedure, which can simulate plate debonding in EB FRP plated masonry, is first described. The developed numerical program is then: used to explain the mechanism of debonding and the parameters that affect this debonding mechanism; compared with plated beam tests first reported in this paper; and used to illustrate the plate debonding mechanism and the substantial increases in out of plane strength that can be achieved.
Quantitative High-Resolution CpG Island Mapping with Pyrosequencing™ Reveals Disease-Specific Methylation Patterns of the CDKN2B Gene in Myelodysplastic Syndrome and Myeloid Leukemia
Authors: Brakensiek Kai , Wingen Luzie U , Länger Florian , Kreipe Hans , Lehmann Ulrich
Published: November 2006

Background: Gene silencing through aberrant CpG island methylation is the most extensively analyzed epigenetic event in human tumorigenesis and has huge diagnostic and prognostic potential. Methylation patterns are often very heterogeneous, however, presenting a serious challenge for the development of methylation assays for diagnostic purposes.

Methods: We used Pyrosequencing™ technology to determine the methylation status of 68 CpG sites in the CpG island of the CDKN2B gene [cyclin-dependent kinase inhibitor 2B (p15, inhibits CDK4)], frequently hypermethylated in myeloid malignancies, in a series of bone marrow samples from patients with myelodysplasia and myeloid leukemia (n = 82) and from 32 controls. A total of 7762 individual methylation sites were quantitatively evaluated. Precision and reproducibility of the quantification was evaluated with several overlapping primers.

Results: The use of optimized sequencing primers and the new Pyro Q-CpG™ software enabled precise and reproducible quantification with a single sequencing primer of up to 15 CpG sites distributed over ∼100 bp. Extensive statistical analyses of the whole CpG island revealed for the first time disease-specific methylation patterns of the CDKN2B gene in myeloid malignancies and small regions of differential methylation with high discriminatory power that enabled differentiation of even low-grade myelodysplastic syndrome samples from the controls, a result that was confirmed in an independent group of 9 control and 36 patient samples.

Conclusion: The precise quantitative methylation mapping of whole CpG islands is now possible with Pyrosequencing software in combination with optimized sequencing primers. This method reveals disease-specific methylation patterns and enables the development of specific diagnostic assays.
Fatigue Prediction of Lightweight Thermoplastic Fiber-Metal Laminates
Authors: Kang H. , Reyes-Villanueva G.
Published: November 2006

Lightweight thermoplastic-based fiber-metal laminates were developed based on a self-reinforced polypropylene and a glass fiber-reinforced polypropylene composite material with two sheets of aluminum alloy 2024-T3. The laminates were manufactured using a fast one step cold press manufacturing procedure. The mechanical behavior of the laminates was then investigated under tensile and fatigue loading conditions. The tensile properties of the plain aluminum, the composite materials, and the thermoplastic fiber-metal laminates (TFML) were investigated at quasi-static rates of loading. The fatigue tests were also conducted under load control based on the ASTM E 466 standard procedure. Various loading cycles were employed for the fatigue tests in order to minimize the possibility of heat generation on the composite materials. Three different load levels were applied for the fatigue specimens with zero to max loading. Results have shown that the glass fiber-reinforced polypropylene hybrid systems exhibited higher fatigue strength than the self-reinforced polypropylene based fiber-metal laminates. Following this, a simple prediction method for fatigue life of the TFMLs has been introduced. It is clearly indicated that the stress ranges calculated using the proposed method for the monolithic AL2024-T3 and the TFMLs are very similar at the same cycles to failure.
Solubility of ThO2·xH2O(am) and the formation of ternary Th(IV) hydroxide-carbonate complexes in NaHCO3-Na2CO3 solutions containing 0−4 M NaCl
Authors: Altmaier M. , Neck Volker , Denecke Melissa A. , Yin R. , Fanghänel Thomas
Published: November 2006

The solubility of ThO2· x H2O(am) is studied at I=0.1−4.0 M (NaHCO3-Na2CO3-NaCl) and 22 °C. Several sets of closed system experiments are performed at total carbonate concentrations of C
tot=[HCO3
-]+[CO3
2-]=0.02 and 0.1 M in the range pHc = 8−11. In our recent study at I=0.5 M, the simultaneous evaluation of solubility data at widely varied pHc and carbonate concentrations has shown that Th(OH)(CO3)4
5-, Th(OH)2(CO3)2
2- and Th(OH)4(CO3)2- are the most important ternary complexes. The present results at I=0.1−4.0 M are used to describe the ionic strength dependence of the equilibrium constants logK
s, 1yz
(for the reactions Th(OH)4(am)+zCO3
2-↔Th(OH)
y
(CO3)
z

4-y-2z
+(4-y)OH-) with the SIT. EXAFS measurements in 0.1 and 1.0 M carbonate solutions support the calculated speciation. They show clearly different spectra for the predominant species Th(OH)(CO3)4
5- and Th(CO3)5
6-, respectively.
Ion interaction (SIT) coefficients for the Th4+ion and trace activity coefficients in NaClO4, NaNO3and NaCl solution determined by solvent extraction with TBP
Authors: Neck Volker , Altmaier M. , Fanghänel Thomas
Published: November 2006

Trace activity coefficients of the Th4+ion in dilute to concentrated NaClO4, NaNO3and NaCl solutions ([H+]=0.01−0.02 M) have been determined at 22 °C from liquid-liquid phase equilibria with 10−50 vol.% TBP inn-dodecane. Using the specific ion interaction theory (SIT) to describe these equilibria as a function of the medium electrolyte concentration, the following ion interaction coefficients are calculated: ε(Th4+, ClO4-)=0.70±0.06 kg/mol and ε(Th4+, NO3-) = 0.31±0.12 kg/mol. The latter value differs considerably from ε(Th4+, NO3-) = 0.11±0.02 kg/mol used in the NEA-TDB. The low distribution coefficients atmNaCl<3 mol/kg do not allow the linear SIT extrapolation toI=0, but the equilibrium constants in 2.5−5.0 m NaCl are compatible with the NEA-TDB value of ε(Th4+, Cl-)=0.25±0.03 kg/mol.

The SIT coefficients determined for the Th4+ion follow the linear correlations between known values of ε(MZ+, NO3-), ε(MZ+, Cl-) and ε(MZ+, ClO4-) for non-complexed cations MZ+withZ=1−4, including ε(Pu4+, ClO4-)=0.82±0.07 kg/mol and ε(Pu4+, Cl-)=0.37±0.05 kg/mol calculated from data accepted in the NEA-TDB. The interaction coefficients in the series of the tetravalent actinide ions show a slight systematic dependence on the ionic radius.
Leaching of neptunium from garnet- and murataite-based ceramics
Authors: Perevalov S. , Stefanovsky Sergey V. , Yudintsev S. V. , Mokhov A. V. , Ptashkin A. G.
Published: November 2006

Leach resistance of neptunium-doped garnet- and murataite-based ceramics with calculated compositions (in wt.%: 38 Fe2O3, 21 Gd2O3, 16 NpO2, 15 ZrO2, 10 CaO and 55 TiO2, 10 Mn2O3, 10 CaO, 10 NpO2, 5 ZrO2, 5 Al2O3, 5 Fe2O3 respectively was studied. The samples were prepared from pre-activated oxide mixtures by sintering/melting in platinum ampules at 1450 °C. The murataite ceramic is composed of predominant murataite structure phases with five- (5C) and eight-fold (8C) elementary fluorite unit cell and minor rutile (≤5% of total bulk). The garnet-based sample is a polyphase ceramic and consists of major garnet phase, interstitial Fe2O3 and Ca-Fe-phase, and rare grains of (Ca,Zr,Np)O2-phase (cubic solid solution) included in the larger garnet grains. The edge of the garnet grains is enriched with Np as compared with their rim by approximately 1.5−2 times. Np leach-rates were measured using an ANS_16.1 test. Np leach rate from the murataite-based ceramic reduced significantly from 2.44×10-6 g/(cm2 day) within the first 2 hours of leaching to 3.41×10-9 g/(cm2 day) at 672 hours of leaching. At the same time for the garnet-based ceramic corresponding values were 1.49×10-5 g/(cm2 day) and 1.77×10-6 g/(cm2 day), respectively. Higher leach rates at early periods are due to the dissolution of trace phases and Np release from defect surfaces. Leach rate values at later periods of leaching are characteristic of the “equilibrium” leach rate of the element (Np). Much higher Np leaching from the garnet ceramic may be due to 1) higher concentration of Np at the edge of the garnet grains with a relatively low chemical durability; 2) leaching of Np traces from highly soluble minor Np-Zr-rich phase.
Rare Earth element (REE) incorporation in natural calcite: Upper limits for actinide uptake in a secondary phase
Authors: Stipp S. L. S. , Christensen J. T. , Lakshtanov L. Z. , Baker J. A. , Waight T. E.
Published: November 2006

Secondary minerals have the potential to sequester escaped actinides in the event of a radioactive waste repository failure, but currently, data to define their maximum uptake capacity are generally lacking. To estimate a maximum limit for solid solution in calcite, we took advantage of the behavioural similarities of the 4f-orbital lanthanides with some of the 5f-orbital actinides and used rare Earth element (REE) concentration as an analogue. A suite of 65 calcite samples, mostly pure single crystals, was assembled from a range of geological settings, ages and locations and analysed by isotope dilution MC-ICP-MS (multiple-collector inductively-coupled plasma mass spectroscopy). All samples were shown to contain significant lanthanide concentrations. The highest were in calcite formed from hydrothermal solutions and from carbonatite magma. Maximum total mole fraction of REE was 4.72×10-4, which represents one substituted atom for about 2000 Ca sites. In comparison, synthetic calcite, precipitated at growth rates slow enough to insure solid solution formation, incorporated 7.5×10-4 mole fraction Eu(III). For performance assessment, we propose that 7.5 mmole substitution/kg calcite should be considered the upper limit for actinide incorporation in secondary calcite. The largest source of uncertainty in this estimate results from extrapolating lanthanide data to actinides. However, the data offer confidence that for waters in the hydrothermal temperature range, such as in the near-field, or at groundwater temperatures, such as in the far-field, if calcite formation is favoured and actinides are present, those with behaviour like the trivalent lanthanides, especially Am3+ and Cm3+, will be incorporated. REE are abundant and widely distributed, and they have remained in calcite for millions of years. Thus, one can be certain that incorporated actinides will also remain immobilised in calcite formed in fractures and pore spaces, as long as solution conditions do not favour complete dissolution. Partial dissolution only results in resequestration to calcite again.
Investigation of complexation of thorium by humic acid using chemically immobilized humic acid on silica gel
Authors: Szabó Gy. , Guczi J. , Reiller Pascal , Geckeis Horst , Bulman R. A.
Published: November 2006

To model the influence of humic substances on the migration of tetravalent actinides (Pu, Np, U) in and around nuclear waste repositories we have immobilized humic acid on silica gel and investigated its complexation of Th(IV). It is anticipated that this material might serve as a geochemical model of the humate-coated minerals that are likely to be present in the vicinity of the repositories. The binding of Th(IV) by the immobilized humic acid was examined at pH 4, 5 and 6 in 0.1 mol L-1NaClO4by the batch method. Th(IV)-humate conditional interaction constants have been evaluated from data obtained from these experiments by using non-linear regression of binding isotherms.
Correlation between X-ray chemical shift and partial charge in Tc(IV) complexes: Determination of Tc partial charge in TcnOy(4n-2y)+
Authors: Poineau Frédéric , Fattahi Massoud , Grambow Bernd
Published: November 2006

The chemical shift of the X-ray absorptionK-edge of Tc(IV) complexes determined by X-ray Absorption Spectroscopy (XAS) measurement was studied. A correlation between edge position (ΔE) and partial charge on Tc atoms (δTc) was determined. This correlation was used to determinate δTcin TcnOy(4n-2y)+. Furthermore, a theoretical relation between δTcand the charge of TcnOy(4n-2y)+, was also established and the overall charge of this complex was estimated.
Oxidation and dissolution rates of UO2(s) in carbonate-rich solutions under external alpha irradiation and initially reducing conditions
Authors: Suzuki Tomo , Abdelouas A. , Grambow Bernd , Mennecart Thierry , Blondiaux G.
Published: November 2006

This paper describes the effects of aqueous carbonate concentrations on the UO2 oxidation and dissolution rates under an alpha beam irradiation in a cyclotron. As solid samples, UO2 colloids were synthesized by nano-particle precipitation. The specific surface area obtained is 85.3 m2/g. All aqueous solutions were buffered in the pH range 8<pH<9.

The observation of particles under TEM and X-ray diffraction showed well-crystallized UO2. Molecular radiolysis products such as H2O2 and carbonate degradation products where analysed. Solution analysis of dissolved uranium and of radiolytically generated H2O2 allowed to deduce dissolution rates of UO2 as well as H2O2 consumption rates (deduced from the H2O2 concentrations in presence of UO2 colloids and those in irradiated blank solutions). In absence of carbonate, the dissolution rates of UO2 are much lower than the H2O2 consumption rates. The difference is explained by the oxidation of uranium(IV) at the UO2/solution interface (e.g. formation of U3O7). In contrast, in the presence of carbonate (up to 4×10-2 mol/L), the dissolution rates of UO2 are similar to H2O2 consumption rates. In this case the oxidized uranium is complexed with carbonate ions resulting in highly soluble species as indicated by the geochemical model PHREEQC calculations [UO2(CO3)3
4 -]. The high carbonate concentration did not affect the H2O2 formation/consumption rates. Radiolytic decomposition of carbonate ions and formation of organic radiolytic degradation products were negligible.

The results indicate that under the present experimental conditions, UO2 oxidation by H2O2 and UO2 dissolution are connected as a sequential reaction: for a given H2O2 concentration, UO2 oxidation occurs at a constant rate. At low carbonate concentration, the dissolution of oxidized UO2 is slower than the oxidation rate (hence oxidation is not rate limiting), while at high carbonate concentrations all oxidized UO2 becomes immediately dissolved and UO2 oxidation becomes rate limiting for UO2 dissolution. This mechanism is in agreement with that proposed in the Matrix Alteration Model (MAM).
Leaching of zirconolite ceramics under H+ and He2+ irradiation
Authors: Tribet M. , Gavarini S. , Toulhoat N. , Monocoffre N. , Chevarier A. , Jegou Christophe , Leturcq G. , Corbel C. , Toulhoat P.
Published: November 2006

Zirconolite is a candidate host material for conditioning minor tri- and tetra-valent actinides arising from enhanced nuclear spent fuel reprocessing and partitioning, which can be disposed in a geological repository for nuclear waste. Its chemical durability has been studied here under charged particle-induced radiolysis (He2+ and proton external beams) to identify possible effects on dissolution rates and mechanisms in pure water. Two geometries of experiments have been used to evaluate the influence of the following parameters: solid irradiation, Linear Energy Transfer (LET) at the interface and total deposited energy. Preliminary results on the elemental releases due to the enhanced dissolution of the zirconolite surface during charged particle-induced irradiation are first presented. Then, we focus on H2O2 production which is one of the major molecular species, created under water radiolysis, and likely to interact with the zirconolite surface. In presence of zirconolite, first results indicate an apparent consumption of the radiolytic hydrogen peroxide or its precursors compared to the production in pure water calculated from the primary yield G
H2O2
. The measured H2O2 concentration varies linearly with the total deposited energy in water over the irradiation duration (between 1 h and 6 h) and in the conditions of our experiments. Moreover, the H2O2 concentration decreases when the local density of the deposited energy close to the interface increases. Thus, we suggest that the mechanism(s) leading to the consumption of H2O2 or its precursors involve zirconolite surface reactions.
Cm(III) sorption onto γ-Al2O3: New insight into sorption mechanisms by time-resolved laser fluorescence spectroscopy and extended X-ray absorption fine structure
Authors: Rabung Thomas , Geckeis Horst , Wang X. K. , Rothe Jörg , Denecke Melissa A. , Klenze R. , Fanghänel Thomas
Published: November 2006

Sorption of trivalent Cm onto γ-Al2O3is investigated by time-resolved laser fluorescence spectroscopy (TRLFS). The pH dependent sorption of Cm(III) is followed at constant ionic strength of 0.1 M NaClO4under argon atmosphere in the pH range between 3.5 and 13.2 at a total Cm(III) concentration of 2.5×10-7mol/L. Three different surface-sorbed Cm(III) species appearing at different pH are identified by their emission spectra with peak maxima at 600.6 nm, 602.5 nm, and 605.7 nm using an excitation wavelength of λex=396.6 nm. No variation of the emission decay is observed for the three sorbed species (constant lifetimes of 110 μs). The pH dependent species distribution obtained from peak deconvolution of emission spectra is in agreement with earlier Eu/Cm sorption studies and sorbed species are assigned to >Al−O−Cm(OH)x(2-x)(H2O)5-xinner-sphere complexes. Indirect Cm excitationviaenergy transfer from the solid to the metal ion at λex=355 nm yields emission bands significantly shifted compared to spectra obtained at λex=396.6 nm. We interpret this observation as a hint for the existence of Cm inner-sphere complexes bound to different γ-Al2O3surface sites. The exact nature of those species is presently not known, but they likely involve Cm interaction with Al(OH)3phases at the solid surface which may even dominate the solid surface chemistry. Complementary EXAFS measurements are performed with Lu and Gd, taken as chemical homologues of the trivalent actinides. EXAFS for Gd/Lu(III) sorbed onto γ-Al2O3at pH=6 identifies a single oxygen coordination shell with a high degree of disorder. For Gd this shell consists of 9±1.5 atoms at a 2.45±0.02 Å distance. A coordination number of 7±1.5 and a Lu−O distance of 2.28±0.02 Å is found in the Lu-samples. Those values are quite close to what is known for the respective aquo ions. The large asymmetry in the coordination shell, however, suggests inner-sphere complexation. This is in agreement with TRLFS results showing clearly the existence of inner-sphere surface complexes where the first coordination shell of the trivalent metal ions consists of 5H2O/OH-entities. Together with EXAFS data, a metal ion coordination to four oxygen atoms belonging to the γ-alumina surface is concluded. Both spectroscopic studies indicate a certain variability of surface binding sites for trivalent metal ions.
Modelling sorption data for the actinides Am(III), Np(V) and Pa(V) on montmorillonite
Authors: Bradbury Michael H. , Baeyens B.
Published: November 2006

The retention characteristics of the bentonite near-field engineered barrier proposed in most of the concepts for the deep geological disposal of high-level waste and spent fuel are an important component in repository performance assessment studies. Montmorillonite generally constitutes 65 to 90 wt.% of the bentonite. Sorption edge measurements have been performed at trace concentrations for the actinides Am(III), Np(V) and Pa(V) on purified and conditioned SWy-1 montmorillonite under anoxic, carbonate free conditions. To the best of the author´s knowledge, this is the first time a sorption data set has been measured for 233Pa(V) uptake on montmorillonite. In some earlier work, the 2 site protolysis non-electrostatic surface complexation and cation exchange quasi mechanistic sorption model has been used to model the sorption edges measured for 11 metals with valencies between II and VI. From this study a linear correlation between strong site surface complexation constants and the corresponding hydrolysis constants was established: a Linear Free Energy Relation (LFER). The new measurements for 241Am(III), 239Np(V) and 233Pa(V) fit very well on this previously established LFER. Through the LFER, a chemically consistent picture emerges which explains quantitatively why some metals tend to exhibit very high sorption and others only moderate to weak sorption.
Np(V)O2+sorption on hydroxyapatite-effect of calcium and phosphate anions
Authors: Thakur P. , Moore Robert C. , Choppin Gregory R.
Published: November 2006

The sorption of NpO2+from aqueous solution on hydroxyapatite was studied as a function of the amount of sorbent, initial NpO2+concentration, ionic strength and pcH. The hydroxyapatite was characterized by SEM, EDS, XRD, FT-IR and ICP-MS measurements. At ionic strengths of 0.10 to 5.00 M NaClO4, the sorption increased with increased pcH to a maximum between pcH 8−8.5, then decreased as the pcH increased.

The kinetics of NpO2+sorption on hydroxyapatite followed Lagergren first order kinetics. The temperature dependence of sorption was small in the range of 273−283 K, but increased more sharply at higher temperatures of 298−333 K. The heat of sorption of NpO2+was endothermic and the free energy values were exothermic indicating large, positive entropy. The activation energy for the sorption process was calculated to be 29.52±1.2 kJ/mole. The effect of calcium and phosphate on NpO2+sorption was studied as a function of concentration and pcH.
Uranium(VI) interaction with pyrite (FeS2): Chemical and spectroscopic studies
Authors: Eglizaud Noelle , Miserque F. , Simoni E. , Schlegel M. , Descostes M.
Published: November 2006

The mechanism of uranium(VI) interaction with pyrite was studied by solution chemistry and X-ray Photoelectron Spectroscopy (XPS). Natural pyrite was characterized by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). After equilibration in 10-2 mol L-1 NaNO3, pyrite was reacted with uranium(VI) by the batch method in an anoxic glove box (PO2
<1 ppm) at ambient temperature. The reaction products of uranium, iron and sulphur were characterized (oxidation state, chemical environment) by XPS. Quantitative analysis revealed that only a few atomic percent of uranium is retained at the pyrite surface. The U4f core level binding energies are consistent with the coexistence of an uranium(VI) species and of uranium in a reduced form. No sulphur oxidation products were observed by XPS, but spectral decomposition of the Fe2p lines revealed the presence of iron(III) oxide or (oxy)hydroxide. These results seem to point to a redox reaction between uranium(VI) and pyrite.