bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stability and convergence of efficient Navier‐Stokes solvers via a commutator estimate
Authors: Liu Jian‐Guo , Liu Jie , Pego Robert L. 
Published: March 2007

AbstractFor strong solutions of the incompressible Navier‐Stokes equations in bounded domains with velocity specified at the boundary, we establish the unconditional stability and convergence of discretization schemes that decouple the updates of pressure and velocity through explicit time stepping for pressure. These schemes require no solution of stationary Stokes systems, nor any compatibility between velocity and pressure spaces to ensure an inf‐sup condition, and are representative of a class of highly efficient computational methods that have recently emerged. The proofs are simple, based upon a new, sharp estimate for the commutator of the Laplacian and Helmholtz projection operators. This allows us to treat an unconstrained formulation of the Navier‐Stokes equations as a perturbed diffusion equation. © 2007 Wiley Periodicals, Inc.
Long‐time asymptotics of the nonlinear Schrödinger equation shock problem
Authors: Buckingham Robert , Venakides Stephanos 
Published: March 2007

AbstractThe long‐time asymptotics of two colliding plane waves governed by the focusing nonlinear Schrödinger equation are analyzed via the inverse scattering method. We find three asymptotic regions in space‐time: a region with the original wave modified by a phase perturbation, a residual region with a one‐phase wave, and an intermediate transition region with a modulated two‐phase wave. The leading‐order terms for the three regions are computed with error estimates using the steepest‐descent method for Riemann‐Hilbert problems. The nondecaying initial data requires a new adaptation of this method. A new breaking mechanism involving a complex conjugate pair of branch points emerging from the real axis is observed between the residual and transition regions. Also, the effect of the collision is felt in the plane‐wave state well beyond the shock front at large times. © 2007 Wiley Periodicals, Inc.
The relationship of the methylenetetrahydrofolate reductase C677T gene polymorphism in Turkish type 2 diabetic patients with and without nephropathy
Authors: Eroglu Z. , Erdogan M. , Tetik A. , Karadeniz M. , Cetinalp S. , Kosova B. , Gunduz C. , Ozgen A. G. , Yılmaz C. 
Published: March 2007

AbstractBackgroundPoor glycaemic control, hypertension and duration of diabetes are risk factors for the development of diabetic nephropathy, but there may be genetic factors. Recently, a common C to T mutation at nucleotide position 677 of the MTHFR gene (MTHFR677C > T) has been reported to be correlated with hyperhomocysteinemia and the severity of coronary artery disease as macroangiopathy. We aim to investigate Turkish type 2 diabetic patients with/without diabetic nephropathy and healthy group and examine the contribution of the MTHFR gene polymorphism to the development of diabetic nephropathy.MethodsDNA was extracted from peripheral leukocytes of the subjects. Genotyping of the MTHFR C677T polymorphism for all individuals was performed by melting curve analysis of the generated amplicons after real‐time online PCR.ResultsThis genotype distribution did not differ between control subjects and type 2 diabetic patients in which 6.8% were TT, 43.7% were CT and 49.5% were CC (χ2 = 0.201, p > 0.05). The frequency of the mutant T allele was 23.4% in diabetic patients with nephropathy versus 33.0% in those without nephropathy. The genotype frequencies were TT, 2.1%; CT, 46.6%; CC, 55.3% in diabetic patients with nephropathy versus TT, 10.7%; CT, 44.6%; CC, 44.6% in those without nephropathy.ConclusionsThe MTHFR genotype and allele frequencies were not different between diabetic patients with and without nephropathy (χ2 = 3, 386, p > 0.005; χ2 = 2.320, p > 0.005, respectively). Therefore, we conclude that the MTHFR gene polymorphism is not associated with the development of diabetic nephropathy in Turkish type 2 diabetic patients. Copyright © 2007 John Wiley & Sons, Ltd.
No essential role for tripeptidyl peptidase II for the processing of LCMV‐derived T cell epitopes
Authors: Basler Michael , Groettrup Marcus 
Published: March 2007

AbstractThe proteasome is critically involved in the production of MHC class I‐restricted T cell epitopes. Approximately 20% of all peptides generated by the proteasome are too large for direct presentation by MHC class I molecules. Reits et al. (Immunity 2004. 20: 495–506) suggested that a major portion of proteasomal products are larger than 15 amino acids and require further degradation by the tripeptidyl peptidase II (TPPII) before becoming ligands of MHC class I molecules. Using the well‐characterized lymphocytic choriomeningitis virus (LCMV) model, the role of TPPII in the processing of several LCMV‐derived T cell epitopes was investigated. In contrast to Reits’ proposal, TPPII inhibition and TPPII overexpression experiments revealed that five out of six LCMV‐derived CD8+ T cell epitopes were not affected by inhibition of TPPII, while one epitope (GP276) was slightly reduced upon TPPII overexpression. Additionally, we demonstrated that the processing of two epitopes derived from ovalbumin and murine cytomegalovirus were not altered by TPPII inhibition. We propose that TPPII is not generally required for the production of MHC class I peptides, but the presentation of some peptides can be negatively affected by TPPII.
The impact of HLA‐B micropolymorphism outside primary peptide anchor pockets on the CTL response to CMV
Authors: Burrows Jacqueline M. , Wynn Katherine K. , Tynan Fleur E. , Archbold Julia , Miles John J. , Bell Melissa J. , Brennan Rebekah M. , Walker Susan , McCluskey James , Rossjohn Jamie , Khanna Rajiv , Burrows Scott R. 
Published: March 2007

AbstractThe factors controlling epitope selection in the T cell response to persistent viruses are not fully understood, and we have examined this issue in the context of four HLA‐B*35‐binding peptides from the pp65 antigen of human cytomegalovirus, two of which are previously undescribed. Striking differences in the hierarchy of immunodominance between these four epitopes were observed in healthy virus carriers expressing HLA‐B*3501 versus B*3508, two HLA‐B allotypes that differ by a single amino acid at position 156 (HLA‐B*3501, 156Leucine; HLA‐B*3508, 156Arginine) that projects from the α2 helix into the centre of the peptide‐binding groove. While HLA‐B*3501+ individuals responded most strongly to the 123IPSINVHHY131 and 366HPTFTSQY373 epitopes, HLA‐B*3508+ individuals responded preferentially to 103CPSQEPMSIYVY114 and 188FPTKDVAL195. By comparing peptide‐MHC association and disassociation rates with peptide immunogenicity, it was clear that dissociation rates correlate more closely with the hierarchy of immunodominance among the four pp65 peptides. These findings demonstrate that MHC micropolymorphism at positions outside the primary anchor residue binding pockets can have a major impact on determinant selection in antiviral T cell responses. Such influences may provide the evolutionary pressure that maintains closely related MHC molecules in diverse human populations.
70‐kDa heat shock proteins: Specific interactions with HLA‐DR molecules and their peptide fragments
Authors: Haug Markus , Schepp Carsten P. , Kalbacher Hubert , Dannecker Guenther E. , Holzer Ursula 
Published: March 2007

AbstractHeat shock protein 70 (HSP70):peptide complexes are involved in MHC class I and class II‐restricted antigen presentation enabling enhanced activation of antigen‐specific T cells. Here, we investigated the potential of bacterial and mammalian HSP70 molecules to interact with peptide fragments from HLA‐DR and the corresponding complete HLA‐DR molecules. Peptide fragments were found to interact with DnaK, the HSP70 homologue from E. coli, but less with stress‐inducible human Hsp70. Only a peptide sequence exclusively found in rheumatoid arthritis‐protective HLA‐DR molecules did not interact with DnaK. Subsequently, we investigated the interaction of complete HLA‐DR molecules with HSP70 and detected a specific HSP70:HLA‐DR interaction, with highest affinity for human stress‐inducible Hsp70. In contrast to the peptide fragments, no allele‐specific differences in Hsp70 affinity were detected with complete HLA‐DR molecules. Interaction with HLA‐DR molecules was increased at lowered pH values, whereas HSP70‐chaperoned peptides were released at acidic pH, thus HSP70 could serve as scanner and carrier for antigenic peptides of self or foreign origin and transfer chaperoned peptides onto MHC class II molecules in acidic late endosomal compartments. Our findings indicate that direct interaction between mammalian HSP70 and HLA‐DR molecules could be involved in the HSP70‐mediated enhancement of MHC class II‐restricted peptide presentation and CD4+ T cell activation.
Syntheses and Characterization of Molybdenum/Zinc Porphyrin Dimers Bridged by Aromatic Linkers
Authors: Song Sai‐Nan , Li Dong‐Mei , Wu Jun‐Feng , Zhuang Chang‐Fu , Ding Hong , Song Wen‐Bo , Cui Li‐Feng , Cao Geng‐Zhen , Liu Guo‐Fa 
Published: March 2007

AbstractTwo new heterobinuclear porphyrin dimers, namely [{MoVIO2}‐DBPA‐Zn] (1; H4DBPA = N,N′‐dibenzylidenebis[4‐(10,15,20‐triphenyl‐21H,23H‐porphin‐5‐yl)phenylamine]) and [{MoVIO2}‐PBDA‐Zn] (2; H4PBDA = N,N′‐bis[4‐(10,15,20‐triphenyl‐21H,23H‐porphin‐5‐yl)phenyl]‐1,3‐benzenedicarboxamide), have been synthesized. These bis(porphyrin)s were obtained by treating 5‐(p‐aminophenyl)‐10,15,20‐triphenylporphyrinatomolybdenum and ‐zinc with benzene‐1,4‐dicarboxaldehyde or benzene‐1,3‐dicarboxylic acid. They have been characterized by UV/Vis, IR, X‐ray photoelectron, luminescence, and 1H NMR spectroscopy, and their TG‐DTA behavior and molar conductances have also been determined. Th cis‐dioxomolybdenum(VI) unit in these complexes is contained in one of the porphyrin moieties and zinc(II) ion is tetracoordinated in the other. Their electrochemical properties have also been investigated in detail. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
A Trinuclear Aqua Cyano‐Bridged Ruthenium Complex [{(η5‐C5H5)(PPh3)2Ru(μ‐CN)}2RuCl2(PPh3)(H2O)]PF6: Synthesis, Characterization and Crystal Structure
Authors: Vertlib Viatcheslav , Figueira João , Mesquita José , Rodrigues João , Nättinen Kalle , Rissanen Kari 
Published: March 2007

AbstractThe organometallic trinuclear aqua cyano‐bridged complex [{(η5‐C5H5)(PPh3)2Ru(μ‐CN)}2RuCl2(PPh3)(H2O)]PF6 (1), in which the fragment [RuCl2(PPh3)(H2O)] acts as a bridge and an acceptor group between the two terminal cyclopentadienyl ruthenium cyano moieties, was isolated in moderate yield from the reaction of [(η5‐C5H5)(PPh3)2RuCN] with [RuCl2(PPh3)3] in THF. To the best of our knowledge, compound 1 is one of the few examples of a trinuclear array of ruthenium fragments bridged by the nitrogen atom of the–C≡N– group (Ru–C≡N–Ru′–N≡C–Ru) with a Ru‐coordinated water molecule. The new aqua complex was structurally characterized by FTIR, 1H, 13C, and 31P NMR spectroscopy, mass spectrometry, elemental analysis, single‐crystal X‐ray diffraction, and cyclic voltammetry. The title complex crystallizes in a triclinic unit cell a = 17.3477(6) Å, b = 17.8551(5) Å, c = 18.2460(7) Å, α = 95.693(2)°, β = 111.648(2)°, and γ = 97.839(2)° in the space group P$\bar {1}$ with Z = 2.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
New Massarilactones, Massarigenin E, and Coniothyrenol, Isolated from the Endophytic Fungus Coniothyrium sp. from Carpobrotus edulis
Authors: Kock Ines , Krohn Karsten , Egold Hans , Draeger Siegfried , Schulz Barbara , Rheinheimer Joachim 
Published: March 2007

AbstractNew massarilactones C (3) and D (4), massarigenin E (5), and coniothyrenol (6) were isolated from Coniothyrium sp. together with the known graphislactone A (1) and massarilactone A (2). The relative configuration of coniothyrenol (6) with an unprecedented benzo[a]xanthene skeleton and ten chirality centers was determined by 1D‐ and 2D‐NMR spectroscopy.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Highly Stereoselective Synthesis of Stereochemically Defined Polyhydroxylated Propargylamines by Alkynylation of N‐Benzylimines Derived from (R)‐Glyceraldehyde
Authors: Díez Roberto , Badorrey Ramón , Díaz‐de‐Villegas María D. , Gálvez José A. 
Published: March 2007

AbstractThe addition of the lithium derivative of tert‐butyldimethylsilyl propargyl ether to N‐benzylimines derived from (R)‐2,3‐O‐isopropylideneglyceraldehyde has been achieved with acceptable yields and high diastereoselectivities. The syn/anti diastereoselectivity of the addition reaction can be controlled and reversed by the appropriate use of Lewis acids as imine precomplexing agents. Double stereodifferentiation processes using imines derived from (R)‐2,3‐O‐isopropylideneglyceraldehyde and (R)‐ or (S)‐α‐methylbenzylamine as starting materials occur with total stereocontrol to afford syn and anti vic‐propargylamino alcohol derivatives with orthogonally protected hydroxymethyl groups on both sides of the central core.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Structure and Biosynthesis of Chaetocyclinones, New Polyketides Produced by an Endosymbiotic Fungus
Authors: Lösgen Sandra , Schlörke Oliver , Meindl Kathrin , Herbst‐Irmer Regine , Zeeck Axel 
Published: March 2007

AbstractThree new fungal polyketide metabolites, chaetocyclinone A to C, were produced by cultures of Chaetomium sp. (strain Gö 100/2), which was isolated from marine algae. The structures of the novel compounds were established by detailed spectroscopic analysis. Additionally, an X‐ray analysis of chaetocyclinone C (5) was performed. Chaetocyclinone A (1) exhibits inhibitory activity against selected phytopathogenic fungi. The biosynthesis of 1 and 5 was studied by feeding 13C‐labelled acetate. The results suggest the polyketide pathway for the isolated metabolites. In the case of chaetocyclinone C (5), we assume an unusual condensation of two highly reactive heptaketide intermediates. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Carbonylative Suzuki–Miyaura Coupling Reaction of Lactam‐, Lactone‐, and Thiolactone‐Derived Enol Triflates for the Synthesis of Unsymmetrical Dienones
Authors: Bartali Laura , Guarna Antonio , Larini Paolo , Occhiato Ernesto G. 
Published: March 2007

AbstractA thorough study of the carbonylative Suzuki–Miyaura cross‐coupling reaction of enol triflates with alkenylboronic acids for the synthesis of unsymmetrical dienones is reported. Conditions were found that enabled the coupling of structurally different enol triflates derived from lactams, lactones, and thiolactones (i.e., cyclic ketene aminal, acetal, and thioacetal triflates, respectively) with various alkenylboronic acids at room temperature under 1 atm of CO pressure with 1–5 % palladium catalyst; the carbonylated products were obtained in 50–86 % overall yields. The methodology allows for a convergent and rapid preparation of substrates useful in conjugate additions and Nazarov reactions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Design and Synthesis of Long‐Wavelength Fluorescent Boronic Acid Reporter Compounds
Authors: Wang Junfeng , Jin Shan , Akay Senol , Wang Binghe 
Published: March 2007

AbstractThree new fluorescent probes based on the 4‐amino‐1,8‐naphthalimide structure were synthesized, and their sugar binding properties were studied by usingD‐fructose,D‐glucose andD‐sorbitol in 0.1Mphosphate buffer at pH 7.4. All three compounds showed fluorescence intensity changes upon addition of sugars. In this series, compound1cgave the longest emission wavelength (570 nm) and fluorescence intensity increases of up to 2.5‐fold after addition ofD‐fructose.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Concise Synthesis of 2,6‐Disubstituted Morpholines by Cyclization of Epoxy Alcohols
Authors: Albanese Domenico , Salsa Matteo , Landini Dario , Lupi Vittoria , Penso Michele 
Published: March 2007

AbstractA novel, straightforward and high yielding synthesis of enantiomerically pure 2,6‐disubstituted morpholines was developed by acid‐catalyzed cyclization of epoxy alcohols. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Polymeric Acid Doped Polyaniline Nanotubes for Oligonucleotide Sensors
Authors: Zhang Lijuan , Peng Hui , Kilmartin Paul A. , Soeller Christian , Travas‐Sejdic Jadranka 
Published: March 2007

AbstractTemplate‐free, self‐assembled polyaniline (PANI) nanotubes were prepared in a solution of poly(methyl vinyl ether‐alt‐maleic acid) (PMVEA) by oxidative polymerization using ammonium persulfate as the oxidant. The weight ratio of the polymeric acid to aniline in the solution had a significant effect on the size of the polyaniline nanotubes as determined by SEM. The outer diameter of the nanotubes increased from 65 nm to 160 nm with increased levels of PMVEA in the reaction solution from 1 to 4 wt/v%. The PANI/PMVEA nanotubes were characterized by FTIR and cyclic voltammetry. The nanotubes were used to construct a simple electrochemical oligonucleotide (ODN) sensor where ODN probes were covalently grafted onto the residual carboxylic acid functionalities on the nanotubes. The potential pulse amperometry technique was used to obtain a direct and fast electrochemical readout.
Wavelet‐based approach for high impedance fault detection of high voltage transmission line
Authors: NengLing Tai , JiaJia Chen 
Published: March 2007

AbstractThis paper presents a new method for high impedance single‐phase ground fault (HIF) detection based on wavelet transform (WT) in the high voltage transmission line. As high impedance single‐phase ground faults usually have low fault currents, it cannot be easily detected by the conventional protection. The voltages and currents vary simultaneously when a ground fault occurs in the transmission lines, even if it is grounded with a high impedance. Therefore, the signals measured by the protective device contain significant transient components. They have much more fault information than the steady components. With the WT the modulus maxima of the zero sequence current, the faulted phase current, and the zero sequence voltage present special characteristics which can be used to detect HIF. The new scheme can also discriminate if the ground fault locates in the forward zone or the backward zone. The realization of the proposed protection device is also described in this paper. Both simulation and field results show that the scheme can detect HIF with high reliability during all operating conditions. Copyright © 2007 John Wiley & Sons, Ltd.
A useful model for multi‐wire concentric neutral cables
Authors: Andreotti Amedeo , Mottola Fabio 
Published: March 2007

AbstractIn literature, as well as in popular software packages for power system analysis and applications, multi‐wire concentric neutral cables are considered to behave like uniform sheath concentric neutral cables, provided that the neutral size is the same. This assumed equivalence greatly simplifies the cable's study, however, it has been proved only for particular operative conditions. Aims of the paper are to analyse limits and applicability of this equivalence, carrying out a rigorous study on the behavior of both types of cables, and to propose an alternative model for multi‐wire concentric neutral cable, which is at the same time simple and effective. Copyright © 2007 John Wiley & Sons, Ltd.
Minimum mean square error vector precoding
Authors: Schmidt David A. , Joham Michael , Utschick Wolfgang 
Published: March 2007

AbstractWe derive theminimum mean square error(MMSE) solution to vector precoding for frequency flat multiuser scenarios with a centralised multi‐antenna transmitter. The receivers employ a modulo operation, giving the transmitter the additional degree of freedom to choose aperturbation vector. Similar to existing vector precoding techniques, the optimum perturbation vector is found with a closest point search in a lattice. The proposed MMSE vector precoder does not, however, search for the perturbation vector resulting in the lowest unscaled transmit power, as proposed in all previous contributions on vector precoding, but finds an optimum compromise between noise enhancement and residual interference. We present simulation results showing that the proposed technique outperforms existing vector precoders, as well as the MMSETomlinson‐Harashima precoder, and compare the turbo‐coded performance to the capacity of the broadcast channel. Copyright © 2007 John Wiley & Sons, Ltd.
Soil chemical surveying: A path to a deeper understanding of prehistoric sites and societies in Sweden
Authors: Linderholm Johan 
Published: March 2007

AbstractA large number of contract archaeological investigations have been conducted in Sweden over the last 10–15 years. In this article, the applicability of soil chemical surveying in connection with contract archaeology is discussed, focusing on soil sampling, soil magnetic susceptibility, and phosphate analysis. Results from case studies from an area of the west coast of southern Sweden are presented. The investigated sites cover periods ranging from the Bronze Age to the Late Iron Age/Medieval time (3500–1000 B.P.). Results show that the chemical loading of prehistoric settlements varies considerably both quantitatively and spatially depending on different socioeconomic strategies and behavior. © 2007 Wiley Periodicals, Inc.
Chemical residues in lime‐plastered archaeological floors
Authors: Barba Luis 
Published: March 2007

AbstractIn addition to research carried out on soils and sediments, there is a parallel field of research applying the same analytical techniques to the study of chemical residues in stuccoes. The most common material used to build floors in Mesoamerica after the Classic period was lime plaster. The study of residues in stuccoes becomes, therefore, a very promising study area. In last 25 years the Archaeological Prospection Laboratory at Mexico's National Autonomous University has developed a research strategy to study human activities based on ethnoarchaeological studies to interpret the distribution of chemical residues in archaeological floors. The most successful applications have been in lime‐plastered surfaces; this article presents a brief review of these works. © 2007 Wiley Periodicals, Inc.
Midden formation and intrasite chemical patterning in Kalinga, Philippines
Authors: Beck Margaret E. 
Published: March 2007

AbstractMiddens are surprisingly fluid entities in occupied communities, as shown by ethnoarchaeological research in Dalupa, Kalinga Province, northern Luzon, the Philippines. This study combines ethnoarchaeological observations of midden formation and disturbance in Dalupa with data from soils and sediments in natural, habitation, and midden contexts, including elemental data for 80 samples collected using inductively coupled plasma‐atomic emission spectroscopy. Most surface samples from habitation areas cluster with midden samples, although samples from the lower parts of theses profiles resemble samples from natural contexts around Dalupa. One explanation is a changing spatial distribution of active middens due to changes in house placement and occupation in Dalupa's history. Some habitation areas that chemically resemble middens may once have held middens, as suggested by the periodic changes in midden location from the cleaning and management of extramural space. Surface scatters of human and animal refuse throughout the habitation area may also contribute to this pattern. © 2007 Wiley Periodicals, Inc.