bluuebunny/crossref_metadata_2025_split huggingface dataset:
Risk factors for procedure‐related fetal losses after mid‐trimester genetic amniocentesis
Authors: Kong Choy Wah , Leung Tse Ngong , Leung Tak Yeung , Chan Lin Wai , Sahota Daljit Singh , Fung Tak Yuen , Lau Tze Kin 
Published: July 2006

AbstractBackgroundThe objective of this study was to determine the institutional pregnancy loss rate following second‐trimester genetic amniocentesis and to ascertain whether factors exist which would identify pregnancies at increased risk of having a procedure‐related fetal loss.SettingUniversity Teaching HospitalMethodsDetails of the procedure and pregnancy outcome of all patients who had amniocentesis planned or performed between 15–22 gestational weeks between January 1997 and June 2004 were extracted from our clinical audit database. The procedure‐related fetal loss rate, defined as all unintended abortions, stillbirths and neonatal deaths without major fetal abnormalities or obvious obstetric causes, was determined and compared to a presumed background fetal loss rate of 0.8% based on a cohort of women who did not undergo the procedure.ResultsA total of 3468 consecutive amniocentesis were performed in 3440 patients with 3498 fetuses. The mean gestational age at amniocentesis was 17.6 ± 1.2 weeks. The majority (98.6%) required only one puncture and a transplacental procedure was required in 2.7% cases. A total of 3465 chromosomal studies were performed. Sixty six cases (1.9%) of major chromosomal abnormalities were detected.Pregnancy outcome was ascertained in all except 26 singleton pregnancies (0.74%). There were 3285 (93.9%) livebirths, 103 (2.9%) termination of pregnancies (TOP), 6 (0.17%) fetal demises before the procedure, and 20 (0.61%) unintended fetal losses due to significant fetal abnormalities or obstetric complications. The remaining 58 fetal losses (1.66%) were classified as potentially procedure‐related, which could be either background fetal losses or procedure‐related. The procedure‐related fetal loss rate after correcting for the background loss rate was 0.86%.Potentially procedure‐related fetal losses were found to be significantly associated with a procedure at 18 weeks or beyond (odds ratio OR = 1.97), a procedure performed for abnormal second‐trimester biochemical screening test (OR = 3.08), a bloody tap (OR = 6.48), and a female fetus (OR = 2.39); but not to the number of punctures (p = 0.66) nor transplacental amniocentesis (p = 0.104).ConclusionsMid‐trimester amniocentesis is associated with a small but significant risk of fetal loss of 0.86%. Copyright © 2006 John Wiley & Sons, Ltd.
Mechanical properties of Nafion and titania/Nafion composite membranes for polymer electrolyte membrane fuel cells
Authors: Satterfield M. Barclay , Majsztrik Paul W. , Ota Hitoshi , Benziger Jay B. , Bocarsly Andrew B. 
Published: July 2006

AbstractMeasurements of the mechanical and electrical properties of Nafion and Nafion/titania composite membranes in constrained environments are reported. The elastic and plastic deformation of Nafion‐based materials decreases with both the temperature and water content. Nafion/titania composites have slightly higher elastic moduli. Thecomposite membranes exhibit less strain hardening than Nafion. Composite membranes also show a reduction in the long‐time creep of ∼40% in comparison with Nafion. Water uptake is faster in Nafion membranes recast from solution in comparison with extruded Nafion. The addition of 3–20 wt % titania particles has minimal effect on the rate of water uptake. Water sorption by Nafion membranes generates a swelling pressure of ∼0.55 MPa in 125‐μm membranes. The resistivity of Nafion increases when the membrane is placed under a load. At 23 °C and 100% relative humidity, the resistivity of Nafion increases by ∼15% under an applied stress of 7.5 MPa. There is a substantial hysteresis in the membrane resistivity as a function of the applied stress depending on whether the pressure is increasing or decreasing. The results demonstrate how the dynamics of water uptake and loss from membranes are dependent on physical constraints, and these constraints can impact fuel cell performance. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2327–2345, 2006
Design and synthesis of ion‐conductive polyphosphazenes for fuel cell applications: Review
Authors: Allcock Harry R. , Wood Richard M. 
Published: July 2006

AbstractNew proton‐conductive fuel cell membranes have been produced by the linkage of acidic functional groups to aryloxy side units attached to a polyphosphazene macromolecular chain. The functional groups include sulfonic acid, phosphonic acid, and sulfonimide units. The different functional groups impart different water retention, proton conduction, and methanol resistance to the membranes. Special advantages are foreseen for uses in direct methanol fuel cells. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2358–2368, 2006
Fully relativistic analysis of the absorption spectra of Ca3Sc2Ge3O12:Ni2+
Authors: Brik M. G. , Ogasawara K. 
Published: July 2006

AbstractSystematic analysis of the energy level schemes, ground state absorption (GSA) and covalency effects for the Ni2+ ion in Ca3Sc2Ge3O12 was performed. The recently developed first‐principles approach to the analysis of the absorption spectra of impurity ions in crystals based on the discrete variational multi‐electron method (DV‐ME) [K. Ogasawara et al., Phys. Rev. B 64, 115413 (2001)] was used in the calculations. As a result, complete energy level schemes of Ni2+ and its absorption spectra at both possible crystallographic positions (distorted octahedral Sc3+ and tetrahedral Ge4+ positions) were calculated, assigned and compared with experimental data. Energies of the charge transfer (CT) transitions for both positions are estimated. Numerical contributions of all possible electron configurations into the calculated energy states were determined. By performing analysis of the molecular orbitals (MO) population, it was shown that the covalency of the chemical bonds between the Ni2+ and O2− ions increases in passing from the hexa‐ to the tetra‐coordinated complex. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thermopower in nearly compensated tunnel junctions
Authors: Maťašovská S. , Hlubina R. 
Published: July 2006

AbstractThe electric current across a tunnel junction between two metals results from the flow of electrons and holes. Generically, one of the two contributions to the current dominates. It is shown that the sign of the thermopower across a tunnel junction provides a direct information about the sign of the dominant charge carriers inside the junction. We predict that for nearly compensated tunnel junctions in which the electron and the hole contributions are of comparable magnitude, the thermopower can be strongly enhanced with respect to the generic case, because of an interference effect between electron and hole paths. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The anisotropy of dielectric properties in the orthorhombic and hexagonal structures of Anhydrite – an ab initio and hybrid DFT study
Authors: Mallia Giuseppe , Dovesi Roberto , Corà Furio 
Published: July 2006

AbstractThe effects of an electric field on the electronic properties of a typical ionic‐covalent compound, Anhydrite (CaSO4), are investigated within the HF level of theory and two different formulations of hybrid DFT functionals (B3LYP [A. Becke, J. Chem. Phys. 98, 5648 (1993)] and F 0.6‐BLYP [F. Corà et al., Structure and Bonding 113, 171–232 (2004)]). An external electric field is applied along each of the three periodic lattice vectors of the orthorhombic and hexagonal structures in order to detect the anisotropy of the response. The perturbation introduced by the field is analysed in terms of Mulliken charges and electron density maps. The largest response is due to a polarisation of the covalent SO bonds of the sulfate ions. The high frequency dielectric tensor, ε ∞, is computed and compared with the experimental value; its anisotropy can be rationalised by the orientation of the sulfate ions relative to the three crystallographic directions. We find that the calculated value of ε ∞ decreases on increasing the percentage of HF exchange in the Hamiltonian; the best match with experiment is given by B3LYP, but a higher percentage of HF exchange is required to reproduce the anisotropy in ε ∞, a feature that we attribute to the better representation of the equilibrium geometry and bond distances in the latter case. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Control of capture‐induced coherences in wave packet transport through nanostructures
Authors: Reiter D. , Glanemann M. , Axt V. M. , Kuhn T. 
Published: July 2006

AbstractTwo different scenarios of controlling occupations and coherences of a quantum dot are discussed. In both cases two wave packets travelling through a quantum wire are used. In the first scenario the two wave packets are generated at both sides of the dot and the coherence is controlled by transport mechanisms. In the second scenario the wave packets are generated at the same spot so that the occupations and coherence are strongly affected by the interference between the laser pulses. Additionally in the latter scenario we show the crossover from the pulse shaping induced coherent control to the control by means of transport. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Floquet versus non‐Floquet solutions for a periodic Hamiltonian
Authors: Lefebvre Roland 
Published: July 2006

AbstractThe situation of a particle interacting with two electric fields, one static and the other periodic in time, may be of interest in the study of the conductance of nanostructures. The static field corresponds to a bias voltage applied between the two electrodes, while the oscillatory field is due to laser illumination. The problem can be described by a variety of Hamiltonians, some time periodic, others not. Following some recent investigations about the solution of the one‐dimensional wave equation for the time‐dependent linear potential, it is shown that there are solutions of the time‐dependent Schrödinger equation with a periodic Hamiltonian that do not follow the usual Floquet pattern of being the product of an energy‐dependent exponential by a time‐periodic factor. We show how to relate the two types of solutions, those conforming with the Floquet ansatz and the non‐Floquet ones. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Extension of the active‐space equation‐of‐motion coupled‐cluster methods to radical systems: The EA‐EOMCCSDt and IP‐EOMCCSDt approaches
Authors: Gour Jeffrey R. , Piecuch Piotr , Włoch Marta 
Published: July 2006

AbstractThe development of the active‐space variants of the electron‐attached (EA) and ionized (IP) equation‐of‐motion coupled‐cluster (EOMCC) methods, in which higher‐than‐doubly excited components of the cluster operator T and higher than 2p‐1h or 2h‐1p components of the electron attaching and ionizing operators R are defined through the use of active orbitals, is discussed. As shown by preliminary test calculations of adiabatic excitation energies and potential energy curves for the low‐lying states of the CH and OH radicals, the basic active‐space EA‐EOMCC and IP‐EOMCC methods, referred to as the EA‐EOMCCSDt and IP‐EOMCCSDt approaches, are capable of accuratelydescribing the ground and excited states of open‐shell systems, even at the moderately stretched nuclear geometries and even for states with a strong multi‐determinantal or doubly excited character, at the low costs that are on the order of those characterizing the standard EOMCC singles and doubles method. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Bio‐Broker: a tool for integration of biological data sources and data analysis tools
Authors: Aldana J. F. , Roldán‐Castro M. , Navas I. , Roldán‐García M. M. , Hidalgo‐Conde M. , Trelles O. 
Published: July 2006

AbstractIn this work we present an architecture for XML‐based mediator systems and a framework for helping systems developers in the construction of mediator‐services for the integration of heterogeneous data sources. A unique feature of our architecture is its capability to manage (proprietary) user's software tools and algorithms, modelled as Extended Value Added Services (EVASs), and integrated in the data flow. The mediator offers a view of the system as a single data source where EVASs are readily available for enhancing query processing. A Web‐based graphic interface has been developed to allow dynamic and flexible EVASs inter‐connection, thus creating complex distributed bioinformatics machines. The feasibility and usefulness of our ideas has been validated by the development of a mediator system (Bio‐Broker) and by a diverse set of applications aimed at combining gene expression data with genomic, sequence‐based and structural information, so as to provide a general, transparent and powerful solution that integrates data analysis tools and algorithms. Copyright © 2006 John Wiley & Sons, Ltd.
Framework for matching requirements elicitation techniques to project characteristics
Authors: Tsumaki Toshihiko , Tamai Tetsuo 
Published: July 2006

AbstractOne of the most difficult jobs for requirements engineers is to select an appropriate RE method for the project at hand. Good engineers make good choices and have skills in applying selected techniques appropriately. Poor engineers usually have a narrow choice range limited by their training and biased by their experience. Once a RE technique that does not fit the current project is selected, the project is doomed to fail. In this article, we propose a framework to characterize typical RE techniques and use it as a base for selecting appropriate techniques at the time a project is started, as well as at the time a change in the nature of the project is recognized, or an obstacle is encountered in defining a suitable set of requirements. Copyright © 2006 John Wiley & Sons, Ltd.
Activation of Ah receptor by pure humic acids
Authors: Bittner Michal , Janošek Jaroslav , Hilscherová Klára , Giesy John , Holoubek Ivan , Bláha Luděk 
Published: July 2006

AbstractHumic substances (HS) are ubiquitous in the environment. However, some studies indicate that HS could induce direct adverse effects on human health and hormone‐like effects in fish, amphibians, and invertebrates. In this study we investigated a possible biochemical mechanism of HS toxicity via activation of the aryl hydrocarbon receptor (AhR). AhR mediates the toxic and biological effects of environmental contaminants such as 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD), but a number of structurally diverse compounds has also been found to activate AhR. Alkali solutions of humic acids (HA) were prepared, and subsequently, lipophilic compounds (including parts of HA) were extracted by liquid–liquid extraction with hexane/dichloromethane. Organic extract of HA was further treated with sulfuric acid to study the role of possible trace persistent contaminants. In vitro dioxin‐like activities of obtained extract and HA solutions have been evaluated using H4IIE.luc cells by determining the ethoxyresorufin‐O‐deethylase (EROD) activity and induction of AhR‐dependent reporter luciferase. Traces of nonpersistent residues in HA with known AhR activity were identified and quantified by GC‐MS. Our results show that an alkali solution as well as organic extract of HA were active in both EROD and luciferase assays, while H2SO4‐treated extract activity was negligible. Only nonsignificant levels of AhR‐inducing contaminants (PAHs and PCBs) were found in the HA samples. Our results indicate that HA or their fragments can elicit significant inductions of AhR‐mediated effects in vitro. To our best knowledge, this study is the first in providing direct evidence of dioxin‐like effects of HA. Further efforts should focus on detailed characterization of potential toxic effects of various HSs. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 338–342, 2006.
Toxicity assessment of reference and natural freshwater sediments with the LuminoTox assay
Authors: Dellamatrice P. M. , Monteiro R. T. R. , Blaise C. , Slabbert J. L. , Gagné F. , Alleau S. 
Published: July 2006

AbstractWe examined the possibility of adapting the LuminoTox, a recently‐commercialized bioanalytical testing procedure initially developed for aqueous samples, to assess the toxic potential of sediments. This portable fluorescent biosensor uses photosynthetic enzyme complexes (PECs) to rapidly measure photosynthetic efficiency. LuminoTox testing of 14 CRM (Certified Reference Material) sediments was first undertaken with (1) a “solid phase assay” (Lum‐SPA) in which PECs are in intimate contact with sediment slurries for a 15 min exposure period and (2) an elutriate assay (Lum‐ELU) in which PECs are exposed for 15 min to sediment water elutriates. CRM sediment toxicity data were then compared with those generated with the Microtox Solid Phase Assay (Mic‐SPA). A significant correlation (P < 0.05) was shown to exist between Lum‐SPA and Mic‐SPA, indicating that both tests display a similar toxicity response pattern for CRM sediments having differing contaminant profiles. The sediment elutriate Lum‐ELU assay displayed toxicity responses (i.e. measurable IC20s) for eight of the 14 CRM sediments, suggesting that it is capable of determining the presence of sediment contaminants that are readily soluble in an aqueous elutriate. Lum‐SPA and Mic‐SPA bioassays were further conducted on 12 natural freshwater sediments and their toxicity responses were more weakly, yet significantly, correlated. Finally, Lum‐SPA testing undertaken with increasing mixtures of kaolin clay confirmed that its toxicity responses, in a manner similar to those reported for the Mic‐SPA assay, are also subject to the influence of grain size. While further studies will be required to more fully understand the relationship between Lum‐SPA assay responses and the physicochemical makeup of sediments (e.g., grain size, combined presence of natural and anthropogenic contaminants), these preliminary results suggest that LuminoTox testing could be a useful screen to assess the toxic potential of solid media. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 395–402, 2006.
Ecotoxicological properties of wastewater treated using tertiary methods
Authors: Petala M. , Samaras P. , Zouboulis A. , Kungolos A. , Sakellaropoulos G. 
Published: July 2006

AbstractThe objective of this work was the examination of the efficiency of coagulation and ozonation processes for the production of reclaimed wastewater with low toxicity. Municipal secondary effluents were treated by FeCl3, Al2(SO4)3 (alum), and a commercial substance at metal ion concentrations of 0.5 and 1 mmol/L. Alternatively, the effluents were treated by ozonation in a semibatch ozone reactor. The feed gas was introduced at a flowrate of 3 L/min containing ozone at various concentrations, ranging between 2.5 and 8 mg/L; ozone residence times were 2, 5, 15, and 30 min. The toxic effects of the advanced treated effluents were examined by a battery of tests using the marine bacteria Vibrio fischeri, the freshwater crustaceans Daphnia magna, Daphnia pulex, and Thamnocephalus platyurus, and the rotifers Brachionus calyciflorus. The addition of alum decreased the toxic effect of reclaimed wastewater on immobilization of D. pulex, from 90 to 60%. Ozonation was also effective for toxicity removal, which decreased to 25% effect on D. pulex after treatment by 2.5 mg O3/L for 2 min. However, acute toxic effects after ozonation, were observed on V. fischeri and were related to ozone gas concentration and contact time. At the highest ozone dosage, the toxicity reached almost 100% inhibition of bioluminescence after 15 min. The toxicity of the ozonated effluents to bacteria decreased with sample storage time and was almost negligible after 48 h, indicating that the potential adverse effect of reclaimed wastewaters on receiving waters might be reduced by storage for a certain time. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 417–424, 2006.
Multiplex PCR‐based detection of potential fumonisin‐producing Fusarium in traditional African vegetables
Authors: Bezuidenhout Cornelius Carlos , Prinsloo Maryn , Van der Walt Anna Margaretha 
Published: July 2006

AbstractCulture‐independent methods employed in fungal genetic studies using in vitro amplification (PCR) and analysis of specific genes or gene fragments have proved to be useful for detection, identification, and molecular taxonomy of various plant pathogens including Fusarium spp. This approach may be faster than culture‐dependent methods, and could especially be of value for the rapid detection of slow‐growing toxin‐producing species in food samples. The present study was aimed at the development and evaluation of multiplex PCR‐based methods for the detection and identification of potential fumonisin‐producing Fusarium spp. in traditional morogo—leafy vegetables supplementing the maize‐based staple diet of rural communities in South Africa. In these rural subsistence settings, some morogo plants grow as weeds in maize fields where they might become contaminated with potential fumonisin‐producing Fusarium strains before being collected for consumption. Substances released by senescent vegetables could induce toxin production during storage. Using fumonisin‐positive MRC Fusarium verticillioides strains as reference cultures, the following primer sets for the detection of specific gene fragments in fumonisin‐positive Fusarium spp. were evaluated: (i) the conserved transcription elongation factor gene (EF‐1), (ii) the FUM1 gene encoding polyketide synthase for fumonisin B1 production, and (iii) 18S rRNA gene. Preliminary results indicated that, these DNA fragments were amplified from MRC reference strains as well as Fusarium spp. isolated from morogo. The annealing temperature for the multiplex PCR was 55°C and each reaction contained 25 pmol of each of the primer sets EF and FUM1 and 12.5 pmol of the 18S primer set. The detection limit of the individual primers was up to 1 ng and for the multiplex up to 10 ng. This demonstrates the potential of this method for the detection of potential fumonisin‐positive strains. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 360–366, 2006.