bluuebunny/crossref_metadata_2025 huggingface dataset:
Phase‐selective crystallization of nickel phosphate VSB‐5 with (2‐hydroxyethyl) trimethylammonium hydroxide as template
Authors: Samadi‐Maybodi A. , Nejad‐Darzi S. K. H.
Published: March 2011

Several nickel phosphate molecular sieves were synthesized by conventional heating (CH) and microwave assisted hydrothermal (MAH). Nickel phosphate VSB‐5 (Versailles Santa Barbara‐5) was synthesized with conventional oven for 72 h or with microwave for 1 h and followed by conventional oven for 48 h in the presence of (2‐hydroxyethyl) trimethylammonium hydroxide as template. The phase transformation is observed by variation of CH time for the synthesis of nickel phosphate molecular sieves. At CH time of 24 h, the VSB‐5 crystal together α‐Ni2P2O7, Ni2P4O12 and unknown phases were produced but the pure VSB‐5 crystal was obtained in the CH time of 48 h or more. At high content of nickel, a mixture of α‐Ni2P2O7, Ni2P4O12 phases and small amount of VSB‐5 crystal, was achieved but pure VSB‐5 crystal was obtained in the lower level of nickel and other phases are vanished. An efficient ultrasonic‐assisted aging was found for the synthesis of nickel phosphate molecular sieve, in which by ultrasonic mixing of 0.5 h followed microwave of 1 h, the CH time is significantly reduced from 48 to 24 h. The morphology of nickel phosphate crystals is highly influenced in the presence of ethylene glycol as co‐solvent. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Discrete and Infinite Metallacyclic Coordination Architectures Based on a Conformationally Flexible Tripodal Aminotriazine‐Derived Polypyridyl Ligand
Authors: Tsai Meng‐Rong , Wu Jing‐Yun , Lai Long‐Li
Published: March 2011

A novel tripodal semi‐rigid ligand, 2,4,6‐tris(3‐picolylamino)‐1,3,5‐triazine (m‐H3tpat), consisting of a triazine central core and three pyridine donating functions attached to flexible –NHCH2– arms has been designed and synthesized. The self‐assembly reactions of m‐H3tpat with copper(II) chloride and cobalt(II) chloride yielded discrete CuII complex [Cu2Cl4(m‐H3tpat)2]·2H2O·2EtOH (1·2H2O·2EtOH) and polymeric CoII complex [Co(m‐H3tpat)2(H2O)2]Cl2 (2), respectively. Complex 1 has a metallacyclophane structure with a metal‐to‐ligand ratio of 2:2. Each copper(II) ion adopts a pentacoordinate square‐pyramidal geometry with a N3Cl2 coordination sphere. Complex 2 exhibits an extended chain structure based on {Co2(m‐H3tpat)2} metallacyclic repeating units. Each cobalt(II) ion adopts a hexacoordinate octahedral geometry with a N2O4 coordination environment. Note that the m‐H3tpat ligand exists in a cis–cis–cis conformation in 1 and a cis–trans–trans conformation in 2, with the central aminotriazine moiety appearing to be an asymmetric‐configured all‐amino tautomer in both conformers. The stabilities of the two coordination‐directed structures may be enhanced by intramolecular π–π interactions between two pyridine rings from two different m‐H3tpat ligands within the metallacyclophane structure of 1 and by a set of complementary double hydrogen bonds (DA–AD arrays) between two aminotriazine moieties of two m‐H3tpat ligands within a metallacyclic unit for 2.
Modular Synthesis of Triazole‐Containing Triaryl α‐Helix Mimetics
Authors: Ehlers Ina , Maity Prantik , Aubé Jeffrey , König Burkhard
Published: March 2011

We describe novel scaffold designs for nonpeptidic α‐helix mimetics. The tricyclic scaffolds contain triazoles and reproduce amino acid side chains i, i+3, and i+7. The three different scaffolds are synthetically readily accessible, allow the introduction of further substituents to increase the versatility, and are suitable for library design. A modular synthesis route using CuI‐ and RuII‐catalyzed azide–alkyne [3+2] cycloadditions as central steps was developed. To demonstrate the methodology, we have prepared a library of compounds containing all three scaffolds.
Sulfoximine‐Directed Single and Double ortho‐Lithiation: Stereoselective Rearrangements of o,o′‐Dilithiophenylsulfoximines to o,N‐Dilithiosulfinylanilines through Anionic Fries Rearrangements of o,o′‐Dilithiophenylsulfinamides
Authors: Wessels Michael , Mahajan Vishal , Boßhammer Stephan , Raabe Gerhard , Gais Hans‐Joachim
Published: March 2011

Treatment of various phenylsulfoximines with nBuLi (1 equiv.) at –78 °C in THF resulted in single ortho‐lithiations and gave the corresponding o‐lithiosulfoximines. According to NMR spectroscopy, the o‐lithiosulfoximines are generally stable at 0 °C. The o‐lithiosulfoximines were efficiently trapped through deuteration, alkylation, silylation, and phosphanylation. Treatment of cyclic phenylsulfoximines also containing H atoms at their α‐positions with nBuLi (1 equiv.) at –78 °C furnished the o‐lithiosulfoximines with high selectivity, whereas similar treatment at –50 °C to room temperature yielded the corresponding α‐lithiosulfoximines. At elevated temperatures, o‐lithiosulfoximines also possessing α‐H atoms underwent quantitative o,α‐transmetalation to afford the corresponding α‐lithiosulfoximines. Treatment of α,α‐disubstituted cyclic and α,α,α‐trisubstituted acyclic phenylsulfoximines with nBuLi (2 equiv.) at low temperatures led to double ortho‐lithiation and furnished the corresponding o,o′‐dilithiosulfoximines. At elevated temperatures, cyclic o,o′‐dilithiophenylsulfoximines underwent multi‐step rearrangements with formation of o,N‐dilithiated benzothiazepine and benzothiazocine S‐oxide derivatives in high yields. Theacyclic o,o′‐dilithiophenylsulfoximine underwent a similar rearrangement and gave the corresponding o,N‐dilithio‐sulfinylaniline derivative. The rearrangements involve 1) elimination of the lithium sulfinamide from the o,o′‐dilithiosulfoximine, 2) a Li–N addition of the lithium sulfinamide to the o‐lithiobenzyne, and 3) an anionic Fries rearrangement of the o,o′‐dilithiophenylsulfinamide. The rearrangements of the o,o′‐dilithiophenylsulfoximines proceeded with overall retention of configuration at sulfur.
Magnetic and electrokinetic manipulations on a microchip device for bead‐based immunosensing applications
Authors: Ambrosi Adriano , Guix Maria , Merkoçi Arben
Published: March 2011

The combination of electrophoretic and magnetic manipulations with electrochemical detection for a versatile microfluidic and bead‐based biosensing application is demonstrated. Amperometric detection is performed in an off‐channel setup by means of a voltammetric cell built at the microchannel outlet and using a gold working electrode. Superparamagnetic particles are introduced and handled inside the channel by means of an external permanent magnet in combination with the electrogenerated flow which allows reproducible loading. The specific detection of phenol as electroactive alkaline phosphatase product is used in this study as proof of concept for a sensitive protein quantification. Characterizations and optimization of different parameters have been carried out in order to achieve the best detection signal. The applicability of the device has been finally demonstrated by the detection of rabbit IgG as model protein after an immunoassay performed on magnetic particles as immobilization platform. A comparison between the electrochemical detection using the developed device and the optical standard detection revealed similar performances with, however, extremely lower amount of reagent used and shorter analysis time. The developed electrophoretic‐ and magnetic‐based chip may open the way to several other biosensing applications with interest not only for other proteins but also for DNA analysis, cell counting, and environmental control.
Accelerated Newton–Raphson power flow
Authors: Li Gan , Zhang Xiao‐Ping , Wang Xi‐Fan
Published: March 2011

This paper introduces the Newton‐like method of modifying the right‐hand‐side vector into the power flow solution. Based on this method, the accelerated Newton–Raphson (ANR) power flow algorithm is proposed. In the proposed algorithm, a constant Jacobian matrix in the correction equations is employed to reduce the computation burden, while the power mismatch vector is multiplied by a factor to guarantee the convergence. Case studies on different test systems under different loading levels are presented to show the accuracy and efficiency of the proposed power flow algorithm. Copyright © 2011 John Wiley & Sons, Ltd.
Ascertaining dementia‐related outcomes for deceased or proxy‐dependent participants: an overview of the Women's Health Initiative Memory Study supplemental case ascertainment protocol
Authors: Gaussoin Sarah A. , Espeland Mark A. , Absher John , Howard Barbara V. , Jones Beverley M. , Rapp Stephen R.
Published: March 2011

Objective

The aim of the study was to compare a two‐staged clinic‐based standardized protocol with a supplemental proxy‐based protocol.

Methods

The Women's Health Initiative Memory Study enrolled 7479 women, aged 65–79 years and free of dementia, in a clinical trial of postmenopausal hormone therapy who were followed for up to 13 years with annual two‐staged clinic‐based standardized protocols to identify incidence of probable dementia. A supplemental proxy‐based protocol, involving telephone administration of the dementia questionnaire, was designed to assess the cognitive status of women who could no longer attend clinic visits because they died (n = 1058) or became dependent (n = 228). Chi‐squared tests were used to compare characteristics of women eligible for proxy‐based versus clinic‐based assessment. Risk factor relationships were described using proportional hazards regression.

Results

Women who were eligible for proxy‐based assessments tended to have worse cognitive impairment risk factor profiles and had higher rates of probable dementia (15.2% vs 3.5%) than clinic‐assessed participants. Augmenting the clinic‐based cases with those identified from proxy interviews reduced undercounting and materially altered observed relationships that years since menopause, smoking status, diabetes, and prior use of hormone therapy had with incidence of probable dementia.

Conclusions

Although proxy interviews were successful in reducing biases in estimated incidence rates and risk factor relationships, it is unlikely that they will fully eliminate many biases. Proxy‐based assessments are necessary in longer term studies to reduce undercounting of dementia cases and to characterize risk factor relationships. Copyright © 2011 John Wiley & Sons, Ltd.
INDIVIDUAL VERSUS AGGREGATE INCOME ELASTICITIES FOR HETEROGENEOUS POPULATIONS
Authors: Paluch Michal , Kneip Alois , Hildenbrand Werner
Published: March 2011

This paper deals with different concepts of income elasticities of demand for a heterogeneous population and the relationship between individual and aggregate elasticities. In general, the aggregate elasticity is not equal to the mean of individual elasticities. The difference depends on the heterogeneity of the population and is quantified by a covariance term. Sign and magnitude of this term are determined by an empirical analysis based on the UK Family Expenditure Survey. It is shown that the relevant quantities can be identified from cross‐sectional data and, without imposing restrictive structural assumptions, can be estimated by nonparametric techniques. It turns out that the aggregate elasticity significantly overestimates the mean of individual elasticities for many commodity groups. Copyright © 2011 John Wiley & Sons, Ltd.
Identification of last interglacial deposits in eastern Beringia: a cautionary note from the Palisades, interior Alaska
Authors: REYES ALBERTO V. , ZAZULA GRANT D. , KUZMINA SVETLANA , AGER THOMAS A. , FROESE DUANE G.
Published: March 2011

Last interglacial sediments in unglaciated Alaska and Yukon (eastern Beringia) are commonly identified by palaeoecological indicators and stratigraphic position ∼2–5 m above the regionally prominent Old Crow tephra (124 ± 10 ka). We demonstrate that this approach can yield erroneous age assignments using data from a new exposure at the Palisades, a site in interior Alaska with numerous exposures of last interglacial sediments. Tephrochronology, stratigraphy, plant macrofossils, pollen and fossil insects from a prominent wood‐rich organic silt unit are all consistent with a last interglacial age assignment. However, six 14C dates on plant and insect macrofossils from the organic silt range from non‐finite to 4.0 14C ka BP, indicating that the organic silt instead represents a Holocene deposit with a mixed‐age assemblage of organic material. In contrast, wood samples from presumed last interglacial organic‐rich sediments elsewhere at the Palisades, in a similar stratigraphic position with respect to Old Crow tephra, yield non‐finite 14C ages. Given that local permafrost thaw since the last interglaciation may facilitate reworking of older sediments into new stratigraphic positions, minimum constraining ages based on 14C dating or other methods should supplement age assignments for last interglacial sediments in eastern Beringia that are based on palaeoecology and stratigraphic association with Old Crow tephra. Copyright © 2011 John Wiley & Sons, Ltd.
Dispersive solid‐phase extraction combined with dispersive liquid–liquid microextraction for the determination of polybrominated diphenyl ethers in plastic bottled beverage by GC‐MS
Authors: Han Yi , Jia Xiaoyu , Liu Xinli , Duan Taicheng , Chen Hangting
Published: March 2011

A simple, inexpensive and reliable analytical method was developed for the determination of polybrominated diphenyl ethers (PBDEs) in polyethylene terephthalate (PET) bottled beverage using GC‐MS. The sample pretreatment using dispersive solid‐phase extraction (DSPE) for removing matrix and dispersive liquid–liquid microextraction (DLLME) for enriching analytes was performed. For the DSPE, different sorbents such as primary amine, secondary amine, C18 and graphitized carbon black were tested for different sample matrices. By means of DSPE, 60–89% of the sample matrices could be removed. Acetonitrile solution obtained by DSPE cleanup was directly used as the dispersant for the subsequent DLLME, which made the combination of the DSPE with the DLLME much more straightforward. Under the optimal conditions, the enrichment factors (EFs) of PBDEs ranged from 199 to 292. Using matrix‐matched calibration, correlation coefficients above 0.994 were found and LODs ranged from 0.0023 to 0.15 μg/L. The recoveries were between 80 and 117% for beverages spiked at three different concentrations (1.0, 5.0 and 10 μg/L) with RSDs ranging from 3.7 to 14.7% (n=5). The results indicated that the combination of DSPE with DLLME was a powerful sample preparation tool for analysis of ultratrace analytes in complicated matrices.
Two‐dimensional strong cation‐exchange liquid chromatography/reversed‐phase pressurized capillary electrochromatography for separation of complex samples
Authors: Wu Yi , Wang Yan , Gu Xue , Zhang Lin , Yan Chao
Published: March 2011

A 2‐D separation platform was constructed using micro strong cation‐exchange liquid chromatography (μ‐SCXLC) and reversed‐phase pressurized capillary electrochromatography (RP‐pCEC) for the analysis of complex samples. Samples were fractionated by the first‐dimension μ‐SCXLC with a linear solvent gradient and then injected into the second‐dimension RP‐pCEC for further separation. The μ‐SCXLC/RP‐pCEC 2‐D system with three separation mechanisms, namely strong cation‐exchange, reversed‐phase chromatography and electrophoresis, provided high selectivity, high resolution and high peak capacity compared to one‐dimensional chromatographic approaches. Separation effectiveness of this 2‐D system was demonstrated by the analysis of different kinds of complex samples, such as traditional Chinese medicine Cortex Phellodendri, bovine serum albumin (BSA) tryptic digest and real serum tryptic digest. A theoretical peak capacity of approximately 1200 was achieved, which proves its promising potential for the separation and analysis of complex samples.
Solid‐phase extraction for metabolomic analysis of high‐salinity samples by capillary electrophoresis–mass spectrometry
Authors: Oikawa Akira , Fujita Nodoka , Horie Ryota , Saito Kazuki , Tawaraya Keitaro
Published: March 2011

Environmental samples such as soil solutions contain inorganic ions such as ${\rm{NH}}_4^+$, K+, Na+, ${\rm{NO}}_3^-$, and ${\rm{PO}}_4^{3-}$ in high concentrations, which must be removed prior to capillary electrophoresis–mass spectrometry analysis to obtain accurate results. However, the separation of these inorganic ions from ionic metabolites, which are the target compounds in capillary electrophoresis–mass spectrometry analysis, is difficult because the physicochemical properties of the inorganic ions are similar to those of the ionic metabolites. In this study, we used various solid‐phase extraction (SPE) columns for the purification of the samples containing inorganic ions in high concentrations. We found that cation‐exchange SPE columns successfully filtered out the inorganic ions while retaining most of the organic compounds, which were easily collected with high recovery rates. In addition, 17 cationic metabolites in the soil solution were quantified by CE‐MS analysis following the SPE purification process. The results suggest that our method can be used to analyze other environmental samples containing inorganic ions in high concentrations.
Female dissociative responding to extreme sexual violence in a chronic crisis setting: The case of Eastern Congo
Authors: Schalinski Inga , Elbert Thomas , Schauer Maggie
Published: March 2011

This cross‐sectional study aimed to examine relationships between the number of traumatizing events, degree of shutdown dissociation, posttraumatic stress disorder (PTSD), and depression. Fifty‐three female survivors of the ongoing war in Congo who sought medical treatment were interviewed. A path‐analytic model was created with paths to PTSD via dissociation, and both the number of self‐experienced and witnessed traumatizing events. Cumulative exposure and dissociation were associated with increased PTSD severity. Posttraumatic stress disorder and witnessing predicted depression when depression was modeled as a consequence of PTSD. Moreover, PTSD mediated the correlation between dissociation and depression. The findings suggest that shutdown dissociation may have value in predicting PTSD, and there is evidence of differential effects of threat to oneself as opposed to witnessing trauma.
SOIL CHARACTERISTICS AND CARBON SEQUESTRATION POTENTIALS OF VEGETATION IN DEGRADED HILLS OF CHITTAGONG, BANGLADESH
Authors: Barua S. K. , Haque S. M. S.
Published: March 2011

The impacts of tree and horticultural plantations, and grassland on soil characteristics in the degraded hills of Chittagong District, Bangladesh are reported on this paper. The carbon sequestration potential and the present value of carbon revenue flow were also estimated for the degraded hills of Chittagong using A. auriculiformis plantations for the purpose. The results showed that the change of land use from degraded hill to vegetation cover had altered the physico‐chemical characteristics of soil in the study area. The organic carbon concentration and storage under vegetated land uses were significantly (p < 0·05) higher than those in the degraded hill areas. The results also showed that about 17 million megagram carbon (MgC) could be sequestered in the degraded hill areas of Chittagong District by planting A. auriculiformis trees in a 15‐year rotation. The present value of revenue flow generated by this sequestration at the current international market carbon price and assuming a realistic market interest rate could be as high as US$ 326 million. The net present value of the revenue stream is expected to be positive. Copyright © 2011 John Wiley & Sons, Ltd.
On ω‐commuting graphs and their diameters
Authors: Raja P. , Vaezpour S. M.
Published: March 2011

Let F be a field, let ω ∈ F, and let n ⩾ 2 be a natural number. In this paper we define the ω‐commuting graph of Mn(F), denoted by Γω(Mn(F)) which is a directed graph. We prove some theorems about the strong connectivity of this graph. Also we show that the induced directed subgraphs on the set of all reducible matrices and the set of all triangularizable matrices are strongly connected graphs. Among other results we determine the diameters of the induced directed subgraphs on the sets of all non‐invertible and nilpotent matrices in Mn(F), exactly. Finally, we find good upper bounds for the diameters of some induced directed subgraphs of Γω(Mn(F)), such as the induced directed subgraphs on the set of all idempotent and diagonazable matrices in Mn(F). © 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim
Fusion integral
Authors: Faroughi M. H. , Ahmadi R.
Published: March 2011

In this paper we shall introduce an operator‐valued integral over a Hilbert space, called the fusion integral. We shall prove that it is additive (finitely or infinitely) but satisfies no additional condition. We shall show that it has the retrieval property and establish a useful connection between the fusion and the Lebesgue integrals. © 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim © 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim
The Aron‐Berner extension, Goldstine's theorem and P‐continuity
Authors: García Ricardo , Jaramillo Jesús A. , Llavona José G.
Published: March 2011

In this paper we show that the Aron‐Berner type extension of polynomials preserves the P‐continuity property. To this end we introduce a new version of Goldstine's Theorem for locally complemented subspaces. © 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim
On the deficiency index of even order symmetric differential expressions with essential spectrum
Authors: Roque Marian P. , Schultze Bernd
Published: March 2011

It shall be shown that for every n, \documentclass{article}\usepackage{amssymb}\pagestyle{empty}\begin{document}$k \in \mathbb {N}$\end{document} with n ⩽ k < 2n, there exist real symmetric differential expressions M of order 2n with nonempty essential spectrum such that d(M) = k. © 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim
Off label use of prescription medicines in children in outpatient setting in Estonia is common
Authors: Lass Jana , Irs Alar , Pisarev Heti , Leinemann Triin , Lutsar Irja
Published: March 2011

Purpose

We aimed to analyse the availability of paediatric information in Summaries of Product Characteristics (SPC) of ambulatory prescription medicines used in children and to compare the SPC information with other information sources.

Methods

In a cross‐sectional drug utilisation study based on national prescription database, we analysed all dispensed prescriptions to subjects of <19 years in 2007. We reviewed SPCs of drugs for paediatric information and categorised them as being labelled, off‐label and unlicensed.

Results

Of 467 334 prescriptions dispensed to 151 476 children, 69% were for labelled, 31% for off‐label and 0.05% for unlicensed drugs. The proportion of prescriptions for drugs being off‐label because of missing data was the highest in genitourinary group (97%) and dermatologicals (74%); off‐label use because of contraindication in the musculoskeletal group (69%). The highest proportion of off‐label drugs was among children aged less than 2 years and the lowest for 2–6‐year‐olds. Contraindicated medicines were most often prescribed to adolescents. Systemic drugs were more frequently prescribed according to the label than topical agents. SPCs were found often not to be comparable with the other information sources.

Conclusions

We show that one‐third of Estonian children treated with prescription medicines are exposed to drugs not labelled for paediatric use. We believe that this is not only partly due to the limited number of paediatric trials but also due to lack of up‐to‐date information in the SPCs. We suggest that paediatric information should be regularly updated in SPCs to ensure that it is based on the best currently available evidence. Copyright © 2011 John Wiley & Sons, Ltd.
Using multimodal blends to elucidate the mechanism of flow‐induced crystallization in polymers
Authors: Okura Masayuki , Chambon Pierre , Mykhaylyk Oleksandr O. , Fairclough J. Patrick A. , Ryan Anthony J.
Published: March 2011

The effect of polydispersity on the formation of flow‐induced, oriented morphology in polyolefins is investigated by polarized light imaging and small angle X‐ray scattering. A torsional shear flow was applied at different temperatures to model polyethylene blends (bimodal and trimodal hydrogenated polybutadienes) comprising of two kinds of long chains with different molecular weight (1080 and 1770 kDa) in a matrix of short chains (18 KDa), and the results were compared to those of polydisperse materials. While a single boundary associated with the threshold flow conditions for the onset of oriented morphology is observed in the bimodal blends, two boundaries corresponding to the orientation of the longest chains (1770 kDa) and next longest chains (1080 kDa) are detected in the trimodal blends. The results obtained, herein, are extended by inference to polydisperse polymers. It is demonstrated that the shear rate dependence of the critical specific work parameter for the onset of oriented morphology in polydisperse polymers is dictated by the molecular weight distribution and that the longest chains mainly control the process with some contribution from shorter chains involved in the formation of flow‐induced precursors at higher flow rates. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011
Evolutionary deployment optimization for service‐oriented clouds
Authors: Wada Hiroshi , Suzuki Junichi , Yamano Yuji , Oba Katsuya
Published: March 2011

This paper focuses on service deployment optimization in cloud computing environments. In a cloud, an application is assumed to consist of multiple services. Each service in an application can be deployed as one or more service instances. Different service instances operate at different quality of service (QoS) levels depending on the amount of computing resources assigned to them. In order to satisfy given performance requirements, i.e. service level agreements (SLAs), each application is required to optimize its deployment configuration such as the number of service instances, the amount of computing resources to assign and the locations of service instances. Since this problem is NP‐hard and often faces trade‐offs among conflicting QoS objectives in SLAs, existing optimization methods often fail to solve it. mathrmE3‐R is a multiobjective genetic algorithm that seeks a set of Pareto‐optimal deployment configurations that satisfy SLAs and exhibit the trade‐offs among conflicting QoS objectives. By leveraging queueing theory, E3‐R estimates the performance of an application and aids defining SLAs in a probabilistic manner. Moreover, E3‐R automatically reduces the number of QoS objectives and improves the quality of solutions further. Experimental studies demonstrate that E3‐R efficiently obtains quality deployment configurations that satisfy given SLAs. Copyright © 2011 John Wiley & Sons, Ltd.
Learning outcomes for peer educators: The national survey on peer education
Authors: Wawrzynski Matthew R. , LoConte Carl L. , Straker Emily J.
Published: March 2011

The National Peer Educator Study gathered data on the learning outcomes that peer educators derive from their work. The results of this study present implications for making peer education a transformative learning process.
Peer educators in classroom settings: Effective academic partners
Authors: Owen Julie E.
Published: March 2011

The author explores the pedagogical benefits and challenges of using peer educators in the classroom, suggests appropriate supports for peer educators in academic environments, and examines innovative uses of peer undergraduate teaching assistants at diverse institutions across the country.
Reducing logic test set size while preserving fault detection
Authors: Kaminski Garrett , Ammann Paul
Published: March 2011

Logic criteria demand inputs that guarantee detection of certain faults. One such criterion, MUMCUT, is composed of three criteria, where each constituent criterion ensures the detection of specific faults. In practice, the criteria may overlap in terms of faults detected, leading to redundant tests, but due to the fact that infeasible requirements do not result in tests, all the constituent criteria are needed. The key insight of this paper is that analysis of the feasibility of the constituent criteria can reduce test set size without sacrificing fault detection for specific faults. This paper introduces a new logic criterion, Minimal‐MUMCUT, and shows how it can apply to minimal DNF, minimal CNF, and general form Boolean expressions. With Minimal‐MUMCUT, a determination is made of which constituent criteria are feasible, and hence necessary, at the level of individual literals and terms. An empirical study found that Minimal‐MUMCUT reduces the test set size, without sacrificing fault detection, regardless of the predicate format. Copyright © 2011 John Wiley & Sons, Ltd.
Laves Phases Ln1–xEuxMg2 (Ln = La, Sm) and the Hydride La0.9Eu0.1Mg2Hy≤7
Authors: Reichert Christian , Kohlmann Holger
Published: March 2011

Mixed crystal Laves phases Ln1–xEuxMg2 (Ln = La, Sm) were prepared from the elements by melting reactions and characterized by X‐ray powder diffraction. In the substitutional range 0 ≤ x ≤ 0.5 cubic Laves phases of the MgCu2 type, for 0.8 ≤ x ≤ 1 (Ln = La) and 0.9 ≤ x ≤ 1 (Ln = Sm), respectively, hexagonal Laves phases of the MgZn2 type are formed, separated from each other by a miscibility gap. The dependence of the lattice parameters on the degree of substitution x follows closely a Vegard type behavior with a(La1–xEuxMg2 (0 ≤ x ≤ 0.5)) = (8.798(3) + 0.00177(8)x) Å and a(Sm1–xEuxMg2 (0 ≤ x ≤ 0.5)) = (8.629(2) + 0.00404(7)x) Å. Analysis of the unit cell volumes suggests europium to be divalent in all mixed Laves phases. Hydrogenation of the Laves phases as followed by in situ thermal analysis is exothermic for all compositions. For the hexagonal europium rich Laves phases the reaction products upon hydrogenation at 6 MPa hydrogen pressure in an autoclave are binary lanthanum hydride and EuMg2H6, the latter being unsubstituted according to lattice parameters refined by Rietveld analysis. For lanthanum‐rich compounds (0 ≤ x ≤ 0.1) ternary hydrides of the tetragonal LaMg2D7 type structure are formed, if the hydrogen pressure is high enough (11 MPa), and heating rates and reaction temperatures are kept low (373 K). The crystal structure of the new hydride La0.9Eu0.1Mg2Hy≤7 was refined from X‐ray powder diffraction data by Rietveld analysis (space group P41212, a = 6.2592(1) Å, c = 9.3759(3) Å, V = 367.322(2) Å3, Z = 4).
Viscoplastic Deformation from the DAE Perspective ‐ a Benchmark Problem
Authors: Scherf O. , Simeon B.
Published: March 2011

Viscoplastic deformation is characterized by a combined system of balance and evolution equations. The application of the Finite Element Method results in a Differential‐Algebraic Equation (DAE) in time. The paper summarizes the most important points of the mathematical model and presents a benchmark problem for numerical comparisons. As computational example, the BDF‐2 method with stepsize control is applied.
A coupled finite‐volume/pseudospectral method
Authors: Droll P. , Schäfer M. , Louchart O. , Bontoux P.
Published: March 2011

Spectral methods (SM) are accurate up to an arbitrary order provided the solution is smooth and the computational domain is simple. On the other hand, when the problem geometry has a complex shape, finite‐volume methods (FVM) have the advantage of being more flexible in fitting the domain boundaries by arbitrarily complex grids. The paper deals with the coupling of a spectral method and a finite‐volume method within a CFD code, enabling the combination of the advantages of both approaches. Considering some representative test cases the features of the coupled method are shown, where special emphasis is given to the coupling mechanism and to the accuracy and efficiency of the method.
Numerical Simulation of Partially Premixed Combustion using the Flamelet Approach
Authors: Herrmann M. , Terhoeven P. , Binninger B. , Peters N.
Published: March 2011

Partially premixed combustion in the flamelet regime as simulated using the two‐scalar level set approach. It combines the flamelet models developed for non‐premixed and premixed Combustion. In the flamelet regime the calculation of the chemical processes can be separated from the pow calculation, so that the flow solver need not resolve any chemical scales. To account for the combustion controlling mechanisms, mixing and flame propagation, transport equations are solved for the mixture fraction Z and the level set function G. These quantities and the scalar dissipation rate X serve as input parameters for pre‐calculated triple flame libraries which provide the chemical composition of the flow and the burning velocity sl. A hybrid tracking capturing scheme is used to solve the governing equations.
Abstract data structures for a finite element package.: Design principles of ALBERT
Authors: Schmidt A. , Siebert K. G.
Published: March 2011

Albert is an Adaptive multi‐Level finite element toolbox using Bisectioning refinement and Error control by Residual Techniques. Its design is based on appropriate data structures holding geometrical, finite element, and algebraic information. Using such data structures, abstract adaptive methods for stationary and tame dependent problems, assembly tools for discrete systems, and dimension dependent tasks like mesh modifications can be provided in a library. This allows dimension‐independent development and programming of a general class of applications. In ALBERT, hierarchical 2d and 3d meshes are stored in binary trees. Several sets of finite elements can be used on the same mesh, either using predefined ones, or by adding new sets for special applications. Depending on the currently used finite element spaces, all degrees of freedom are automatically managed during mesh modifications.
Experiments, Modelling and Analysis of Friction and Impact Oscillators
Authors: Hinrichs N. , Oestreich M. , Popp K.
Published: March 2011

During the past decade nonsmooth dynamical systems have become increasingly important in engineering and other applied sciences as nonsmooth effects are genuinely taken into account and are no longer smoothed out. Due to the lack of smoothness classical mathematical methods are applicable only to a limited degree and require extensions both for analytical and numerical methods. In the present paper the dynamics of nonsmooth oscillators with impact and friction are investigated numerically and by experiments.
Identification and Analysis of Nonlinear Transition Scenarios using NOLOT/PSE
Authors: Hein S. T. , Stolte A. , Dallmann U. Ch.
Published: March 2011

Laminar‐turbulent transition of quasi‐three‐dimensional boundary‐layer flows is investigated by nonlinear nonlocal instability theory based on parabolized stability equations (PSE). A strong TS‐CF interaction scenario is described, which leads to a rapid rise in skin‐friction coefficient indicating imminent breakdown of the laminar flow. The GF‐CF interaction studies reproduce amplitude saturation observed in experiment, but do not provide an explanation for the final breakdown in crossflow‐dominated boundary layers yet.
Numerische Simulation der räumlichen und zeitlichen Entwicklung lokaler Störungen in Grenzschichten
Authors: Laurien E. , Demuth R. , Heiken S. , Hillmann U.
Published: March 2011

Die Entwicklung lokaler Störungen endlicher Amplitude in Grenzschichten ward durch Integration der vollständigen Navier‐Stokes Gleichungen numerisch simuliert. Nichtlineare Anfachungsmechanismen führen über die Streckung einer anfangs vorgegebenen Wirbelstruktur zur Ausbildung freier Scherschichten. In späteren Entwicklungsstadien bildet sich die charakteristische Pfeilspitzenform eines Turbulenzflecks aus, wie er bei der sog. Bypass‐Transition in Experimenten beobachtet wird.
Fully reliable error control in the h‐p‐version of FEM
Authors: Carstensen C. , Funken S. A.
Published: March 2011

Some approaches in the a posteriori error analysis of finite element methods (FEM) are based on the regularity of the exact solution or on a saturation property of the numerical scheme. For coarse meshes those asymptotic arguments are difficult to recast into rigorous error bounds. Here, we will provide reliable computable error bounds which are efficient and complete in the sense that constants are estimated as well. A localisation via a partition of unity yields problems on small domains. Two fully reliable estimates are established, the sharper one solves an analytical interface problem with residuals following Babugka and Rheinboldt. The second estimate yields a modification of the standard residual‐based a posteriori estimate with explicit constants computed from local analytical eigenvalue problems. Emphasis is on the efficiency of the computed error bound, which can be monitored. For some class of triangulations and the h‐version we show that the efficiency constant is smaller than 2.5 and grows only weakly for the h‐p‐version. Numerical experiments support and illustrate the theoretical results.
Meandering Spirals
Authors: Scheel Arnd
Published: March 2011

Spiral wave patterns in chemical reactions and their dynamics have received a lot of interest in the past few years, from the experimental and from the theoretical side. We review some of the recent mathematical results addressing a bifurcation theoretic approach to meandering and drifting tip motions. Special emphasis as laid on the crucial role of euclidean symmetry.
On a general concept for structured media with evolving defects
Authors: Stumpf H.
Published: March 2011

In this paper we present some main aspects for the modelling of structured continua with evolving defects. Taking into account that the evolution of defects as voids, shearbands, cracks and also of phase boundaries in two‐phase materials is governed by non‐classical forces, so‐called configurational forces, we have to generalize the concepts of classical and structured continua to describe the evolution of macro‐ and micro‐defects in moving material bodies.

Taking a very general kinematical model as point of departure we introduce generalized deformation and strain measures and derive macro‐ and micro‐balance laws for deformational and configurational forces postulating a generalized action integral. Assuming that the thermodynamical process is governed by two potentials a dissipation inequality is derived via a generalized Weierstrass excess function.
On the flow around a circular cylinder. Part I: Laminar and transitional regime
Authors: Noack B. R.
Published: March 2011

A concise review about the properties of the laminar and transitional wake (Re < 260) behind a circular cylinder is presented. Some open problems of this flow are outlined.
Maximum entropy principle and texture formation
Authors: Arminjon M. , Imbault D.
Published: March 2011

The macro‐to‐micro transition in a heterogeneous material is envisaged as the selection of a probability distribution by the Principle of Maximum Entropy (MAXENT). The material is made of constituents, e.g. given crystal orientations. Each constituent is itself made of a large number of elementary constituents. The relevant probability is the volume fraction of the elementary constituents that belong to a given constituent and undergo a given stimulus. Assuming only obvious constraints in MAXENT means describing a maximally disordered material. This is proved to have the same average stimulus in each constituent. By adding a constraint in MAXENT, a new model, potentially interesting e.g. for texture prediction, is obtained.
Description of fretting damage by contact mechanics
Authors: Fouvry S. , Kapsa Ph. , Vincent L.
Published: March 2011

Fretting damage is often the origin of catastrophc failure or loss of functionality in many industrial applications. Considered to be a plague for modem industry, this contact loading is encountered in all quasi‐static loadings submitted to vibration and thus concerns many industries. The purpose of this presentation is to develop different mechanical tools allowing a finest understanding of the sliding condition and a better quantification of the fretting damages whch are respectively the crack nucleation through the contact and the wear induced by debris formation.
Friction Models with discrete Layers
Authors: Georg‐Peter Ostermeyer
Published: March 2011

Looking for energy flows inside friction phenomena leads to special formulation of boundary layer in contact regions. The paper presents a local superatom‐discretisation, a special mesoscopic particle approach similar to molecular dynamic techniques, but with respect to thermodynamic laws the particles have inner variables, which indicate temperature information of the particle for instance.

The friction model with discrete layers allows prediction of temperature distributions during the friction process.
Multigrid Methods for the fast Numerical Simulation of Coupled Magnetomechanical Systems
Authors: Schinnerl M. , Schöberl J. , Kaltenbacher M. , Langer U. , Lerch R.
Published: March 2011

A recently developed calculation scheme for the numerical simulation of the transient behavior of magnetomechanical systems is presented. The scheme is based on the Finite‐Element‐Method (FEM) and allows the precise numerical calculation of dynamic rigid motions as well as deformations of magnetic and non‐magnetic materials an a magnetic field. The solution process is considerably accelerated by using different grids for the mechanical and the magnetic field and solving the coupled system with an implicit Multigrid Method (MG).

The applicability of the developed calculation technique will be demonstrated by the 30 computation of the transient behavior of an magnetically excited aluminum plate. Thereby, the parabolic PDE of the magnetic field has to be coupled to the hyperbolic PDE of the mechanical field. Numerical simulation results show good agreement with measured data.
Parameter Identification of Constitutive Models for Fluidsaturated Porous Media within an FE‐Setting
Authors: Mahnken R. , Steinmann P.
Published: March 2011

In this contribution an FE‐algorithm for parameter identification of geometrically‐linear fluid‐saturated porous media is proposed, in which non‐uniform distributions of the state variables such as stresses, strains and excess pore fluid pressure gradient are taken into account. Thereby, a least‐squares functional consisting of experimental and simulated data is minimized, and where the simulated data are obtained with the FE‐method. In order to improve the efficiency of the minimization process, a gradient‐based optimization algorithm is applied, and therefore the corresponding sensitivity analysis is briefly explained. The performance of the strategy is demonstrated for a slope stability problem.
Dynamik isotroper Sandwichplatten mit asymmetrisch angeordneten Schichten
Authors: Adam C. , Heuer R.
Published: March 2011

In der vorliegenden Arbeit wird die Schwingungsantwort mäßig dicker Sandwichplatten mit drei homogenen, isotropen und asymmetrisch aufgebauten Schichten berechnet, wobei keine Einschränkung für die Verhältniswerte der Schichtdicken und Schubmoduli getroffen werden soll. Speziell wird das dynamische Verhalten von polygonalen, frei drehbar gelagerten Platten mit Randversteifung untersucht. In jeder Schicht werden neben der Biegesteifigkeit auch Schubdeformation und Rotationsträgheit berücksichtigt. Es zeigt sich, daß sich die Durchbiegung, analog zur Mindlin'schen Theorie für homogene Platten, aus einem entkoppelten Randwertproblem vierter Ordnung berechnen läßt.
Interactions between Microstructure and Plastic Instabilities in Al‐Zn‐Mg‐Cu Alloy
Authors: Thevenet D. , Mliha‐Touati M. , Zeghloul A.
Published: March 2011

In recent years, inhomogeneous plastic deformation associated with the Portevin‐Le Châtelier (PLC) has received a renewed attention. The PLC effect, commonly called 'jerky flow' or Serrated yielding; is the result of dynamic strain ageing due to dynamic interactions between mobile dislocations, temporarily arrested at obstacles, and dissolved alloying atoms, which diffuse towards dislocations ]1[ So, the microstructure can have an important role on the PLC phenomenon and efforts to understand these mechanisms were the subject of previous researches ]2, 3[ In this work, essentially experimental, we have changed the ageing conditions in order to investigate the effects of precipitates on the jerky flow and its characteristics.
Stress Analysis of Buried Pipelines due to Seismic Motions
Authors: Kocács Á. , Szabó Z.
Published: March 2011

The paper deals with the comparison of different soil‐pipe interaction models on the stems distribution in buried pipelines due to seismic motions. The effect of soil is modeled by springs attached to the pipeline. We showed, that linear characteristics am inappropriate, however, by using nonlinear springs the model is sensitive on the correct load formulation.
On the Numerical Analysis of the Contact Problems at Crane Mechanisms
Authors: Iztok Potrc , Matjaz Sraml
Published: March 2011

In several construction components of crane mechanisms, contact loading is very important, which results in the need for the non‐linear analysis. The numerical treatment of contact problems was performed by the finite element method (FEM). The algorithm of the stiffness update with friction, based on the penalty function method, is included in the numerical calculation of the above mentioned contact problems. The potential contact areas are defined throughout the slide‐line contact elements, which enable the handling of the seperation and sliding of the finite amplitude between the deformable bodies.
An Efficient Method for the Treatment of Bounded Elastic Bodies With Many Cracks
Authors: Rafiee S. , Gross D. , Seelig Th.
Published: March 2011

Presented is a hybrid numerical‐analytical method for the investigation of linear elastic bodies containing many straight (2D) or penny‐shaped (90) cracks. The method of 'pseudo tractions' and its evaluation according to Kachanov (Kachanov, 1998), based on closed form solutions for cracks in unbounded domains, is extended to bounded domains by combination with a boundary element method (BEM). The influence of the boundary on stress singularities of interacting cracks is analyzed. Furthermore, the overall elastic behavior of a finite body containing distributed cracks in various configurations is investigated.
Kopplung starrer und flexibler Strukturbereiche unter Verwendung üblicher Finit‐Elemente‐Diskretisierungen
Authors: Goettlicher B. , Schweizerhof K.
Published: March 2011

Treten in Strukturen Bereiche stark unterschiedlicher Steifigkeiten auf, ist es im Hinblick auf transiente Berechnungen sehr effizient und insbesondere für Überschlagsuntersuchungen sinnvoll, auch bei bereits vernetzten FE‐Strukturen Bereiche relativ hoher Steifigkeit durch Starrkörper zu ersetzen. Mit dieser Maßnahme wird eine schlechte Konditionierung des FE‐Gleichungssystems vermieden und der Berechnungsaufwand in Abhängigkeit vom Anteil der Starrkörper reduziert.

Die Kopplung von starren und flexiblen Teilkörpern erfolgt über Zwangsbedingungen, die auch für geometrisch nicht‐lineare Probleme Gültigkeit haben. Damit können beliebige Teile der FE‐Struktur mit geringen Aufwand als starr modelliert werden und beliebige Randbedingungen definiert werden. Hierbei ist die Problematik großer Rotationen gesondert zu beachten. An einem Schalentragwerk unter statischer Beanspruchung wird exemplarisch die funktionsfähigkeit des Verfahrens diskutiert. Damit steht für die Modellierung ein außerordentlich effizientes Werkzeug zur Verfügung.