bluuebunny/crossref_metadata_2025 huggingface dataset:
Sandwich Complexes Based on the “All‐Metal” Al42− Aromatic Ring
Authors: Mercero Jose M. , Formoso Elena , Matxain Jon M. , Eriksson Leif A. , Ugalde Jesus M.
Published: May 2006

We report on novel sandwichlike structures [Al4MAl4]q− (q=0–2 and M=Ti, V, Cr, Zr, Nb, Mo, Hf, Ta and W) based on the recently synthesized all–metal aromatic Al42− square ring. The sandwichlike structures have two aromatic tetraaluminum square rings which trap a transition‐metal cation from either the first, second, or third row. The stability of the anionic sandwichlike complexes towards electron detachment is discussed, and addition of alkali cations is found to stabilize the 2− charged complexes, preventing spontaneous electron detachment. Once the sandwichlike complexes are formed, the Al42− square properties remain nearly unchanged; this fact strongly supports the hypothesis that in these complexes the Al42− square rings remain aromatic.
Asymmetric Synthesis of O‐Acetylcyanohydrins by Reaction of Aldehydeswith NaCN/KCN Catalyzed by Recyclable Chiral DimericTitanium(IV)/Vanadium(V) Salen Complexes
Authors: Khan Noor‐ul H. , Agrawal Santosh , Kureshy Rukhsana I. , R. Abdi Sayed H. , Mayani Vishal J. , Jasra Raksh V.
Published: May 2006

The efficient catalytic asymmetric addition of an inexpensive and nonvolatile cyanide source such as NaCN or KCN and acetic anhydride to various aldehydes was catalyzed by recyclable dimeric TiIV and VV chiral salen complexes at –20 °C. High chiral induction (96 % ee) in the O‐acetylcyanohydrin was obtained in the case of 2‐fluorobenzaldehyde, and the results achieved with sodium cyanide are quite comparable to those with potassium cyanide. The chiral VV salen complex was found to be the most efficient recyclable catalyst reported so far in the literature, and was better than the TiIV salen system. Both the catalysts were recovered after the first use and recycled effectively four times. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Power‐based, phase‐informed selection of single nucleotide polymorphisms for disease association screens
Authors: Saccone Scott F. , Rice John P. , Saccone Nancy L.
Published: May 2006

Single nucleotide polymorphisms (SNPs) are becoming widely used as genotypic markers in genetic association studies of common, complex human diseases. For such association screens, a crucial part of study design is determining what SNPs to prioritize for genotyping. We present a novel power‐based algorithm to select a subset of tag SNPs for genotyping from a map of available SNPs. Blocks of markers in strong linkage disequilibrium (LD) are identified, and SNPs are selected to represent each block such that power to detect disease association with an underlying disease allele in LD with block members is preserved; all markers outside of blocks are also included in the tagging subset. A key, novel element of this method is that it incorporates information about the phase of LD observed among marker pairs to retain markers likely to be in coupling phase with an underlying disease locus, thus increasing power compared to a phase‐blind approach. Power calculations illustrate important issues regarding LD phase and make clear the advantages of our approach to SNP selection. We apply our algorithm to genotype data from the International HapMap Consortium and demonstrate that considerable reduction in SNP genotyping may be attained while retaining much of the available power for a disease association screen. We also demonstrate that these tag SNPs effectively represent underlying variants not included in the LD analysis and SNP selection, by using leave‐one‐out tests to show that most (approximately 90%) of the “untyped” variants lying in blocks are in coupling‐phase LD with a tag SNP. Additional performance tests using the HapMap ENCyclopedia of DNA Elements (ENCODE) regions show that the method compares well with the popular r2 bin tagging method. This work is a concrete example of how empirical LD phase may be used to benefit study design. Genet. Epidemiol. 2006. © 2006 Wiley‐Liss, Inc.
Rapid and cleaner synthesis of 1,4‐dihydropyridines in aqueous medium
Authors: Sivamurugan V. , Vinu A. , Palanichamy M. , Murugesan V.
Published: May 2006

The present investigation deals with a novel water soluble Lewis acid complex, Zn[(L)proline]2 catalyzed Hantzsch 1,4‐dihydropyridine derivatives syntheses in aqueous medium assisted by microwave irradiation. The microwave promoted syntheses in aqueous medium afforded moderate to excellent yield (up to 98%) within short reaction time and allowed the reaction to take place with low microwave power (200 W). This synthetic methodology provides easier separation of products and the catalyst exhibits recycling ability without loss of its catalytic activity up to five reaction cycles. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:267–271, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20197
Determination of Chitin and Protein Contents During the Isolation of Chitin from Shrimp Waste
Authors: Díaz‐Rojas Erika I. , Argüelles‐Monal Waldo M. , Higuera‐Ciapara Inocencio , Hernández Javier , Lizardi‐Mendoza Jaime , Goycoolea Francisco M.
Published: May 2006

Summary: Accurate determination of chitin and protein contents in crustacean biomass and the intermediate products during the industrial isolation of chitin cannot be made directly from the total nitrogen content, unless the appropriate corrections are applied. This method, however, is affected by the presence of other nitrogen‐containing chemical species that are formed endogenously or by the action of microorganisms during the handling of the sample. Therefore, an alternative rapid method to estimate the contents of these components can be very useful both in research and in various fields of application. An original method has been developed to address this problem. The method consists of the development of a set of equations based on the stoichiometric contents of nitrogen of chitin and protein whereby the amounts of each component can be estimated from the value of the total nitrogen content, provided the rest of the proximate composition of the sample is accurately known. In order to validate the procedure, a set of model mixtures of pure chitin and protein concentrate in the solid state, both extracted from shrimp head waste, are used. Excellent agreement between the predicted and real values of chitin and protein are obtained (R2 = 0.98, slope = 0.90). When the proposed method is tested in the analysis of real samples obtained from five different processing protocols of pretreatment of raw shrimp head, it is found that in general the values of protein and chitin contents throughout the various stages of the process vary as expected.

Variation of the measured total nitrogen versus calculated stoichiometric total nitrogen of the chitin‐protein mixtures.

magnified image

Variation of the measured total nitrogen versus calculated stoichiometric total nitrogen of the chitin‐protein mixtures.
Reducing voxel bleed in hadamard‐encoded MRI and MRS
Authors: Goelman Gadi , Liu Songtao , Gonen Oded
Published: May 2006

The point spread function (PSF) of Hadamard encoding deviates from its ideal profile due to practical (as opposed to intrinsic) reasons. Finite radiofrequency (RF) pulse length and gradient strength cause slice profile imperfections that lead to cross‐talk (“voxel bleed”) as large as 17% for a 1‐KHz bandwidth, 5.12‐ms RF pulse under 3 mT/m. This could adversely affect localization and quantification, and consequently clinical usefulness. A simple modification of the Hadamard RF pulse synthesis that exploits its unique ability to encode noncontiguous slices is proposed and shown to markedly improve the PSF. Computer simulation, in vitro and in vivo experiments confirm the theoretical derivation of voxel bleed reduction from ∼17% to below 5% per Hadamard‐encoded direction. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Blipped multi gradient‐echo slice excitation profile imaging (bmGESEPI) for fast T measurements with macroscopic B0 inhomogeneity compensation
Authors: Truong Trong‐Kha , Chakeres Donald W. , Scharre Douglas W. , Beversdorf David Q. , Schmalbrock Petra
Published: May 2006

With the rapid development of human MRI at field strengths ≥ 7 T, knowledge of T relaxation times at such field strengths is needed to optimize acquisition parameters and understand relaxation mechanisms in many applications. However, standard T measurements (e.g., using conventional multiecho gradient‐echo (GE) sequences) are affected by macroscopic static magnetic field (B0) inhomogeneities, which are particularly severe at high field strength. The multi‐GE slice excitation profile imaging (mGESEPI) method was developed for T measurements in the presence of macroscopic B0 inhomogeneity, but it requires excessive acquisition times at field strengths ≥ 7 T. In this paper a more efficient technique, named blipped mGESEPI (bmGESEPI), is proposed. To demonstrate its advantages, T maps were acquired using a conventional multiecho GE method, the mGESEPI method, and the bmGESEPI method in postmortem and in vivo human brains at 8 T. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Continuous antibiotic infusion for salvage therapy of partially implanted central venous catheter tunnel infections due to staphylococci
Authors: Giacchino M. , Bezzio S. , Chiapello N. , Saracco P. , Fagioli F. , Caviglia I. , Moroni C. , Castagnola E.
Published: May 2006

Tunnel infection is an uncommon but serious complication observed in patients with partially implanted central venous catheters. International guidelines suggest that should include antibiotics and catheter removal. A success rate of only 5–20% was reported without catheter removal. We treated 13 episodes of tunnel Gram‐positive bacterial infection occurring in pediatric patients with cancer or serious blood disorders with 24‐hr intra‐catheter antibiotic continuous infusion. This approach led to a 69% success rate. Continuous infusion might be an attractive option to treat tunnel Gram‐positive bacterial infections when catheter removal might not be feasible or advisable. Pediatr Blood Cancer 2007;49:1010–1012. © 2006 Wiley‐Liss, Inc.
Prenatal diagnosis of a de novo complex chromosome rearrangement (CCR) mediated by six breakpoints, and a review of 20 prenatally ascertained CCRs
Authors: Giardino D. , Corti C. , Ballarati L. , Finelli P. , Valtorta C. , Botta G. , Giudici M. , Grosso E. , Larizza L.
Published: May 2006

Objectives

To describe the cytogenetic and FISH characterization of a prenatally diagnosed de novo complex chromosome rearrangement (CCR), showing the involvement of four chromosomes and six breakpoints, and review the literature concerning prenatally detected CCRs in order to obtain insights into addressing karyotype‐phenotype correlations in prenatal genetic counseling.

Methods

Conventional protocols were used to set up cultures and chromosome preparations. Commercial and homemade probes were used for the FISH analyses.

Results

An apparently balanced de novo t(4;10;20) was prenatally identified by means of cytogenetic analysis. FISH revealed a rearrangement mediated by six breakpoints and the insertion of chromosome 8 material within the 4q region. The pregnancy was interrupted. The fetus showed malformations and anomalous cortical neuron migration. The assembled list of 20 prenatally detected CCRs points to the preferential involvement of chromosomes 4, 6 and 14. The involvement of chromosome 20 is described here for the first time.

Conclusions

FISH analysis is essential for the accurate definition of a complex rearrangement. Phenotype description of fetuses carrying CCRs investigated by means of molecular cytogenetic techniques may contribute to improving and personalizing genetic counseling in prenatal diagnosis. Copyright © 2006 John Wiley & Sons, Ltd.
Synthesis of TiO2–SiO2/polymer core–shell microspheres with a microphase‐inversion method
Authors: Xu Peng , Wang Haitao , Lv Rui , Du Qiangguo , Zhong Wei , Yang Yuliang
Published: May 2006

A novel microphase‐inversion method was proposed for the preparation of TiO2–SiO2/poly(methyl methacrylate) core–shell nanocomposite particles. The inorganic–polymer nanocomposites were first synthesized via a free‐radical copolymerization in a tetrahydrofuran solution, and the poor solvent was added slowly to induce the microphase separation of the nanocomposite and result in the formation of nanoparticles. The average particle sizes of the microspheres ranged from 70 to 1000 nm, depending on the reaction conditions. Transmission electron microscopy and scanning electron microscopy indicated a core–shell morphology for the obtained microspheres. Thermogravimetric analysis and X‐ray photoelectron spectroscopy measurements confirmed that the surface of the nanocomposite microspheres was polymer‐rich, and this was consistent with the core–shell morphology. The influence of the synthetic conditions, such as the inorganic composition and the content of the crosslinking monomer, on the particle properties was studied in detail. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3911–3920, 2006
Thermodynamic stability of In1–x –yGax Aly N on GaN and InN
Authors: Kangawa Yoshihiro , Kakimoto Koichi , Ito Tomonori , Koukitu Akinori
Published: May 2006

We studied the thermodynamic stability of InGaAlN alloy based on calculations of enthalpy of mixing using empirical interatomic potentials. We also investigated the influence of lattice constraint from the bottom layer, i.e., (0001)GaN or (0001)InN, on thermodynamic stability of InGaAlN thin films. The results suggest that the maximum point of enthalpy of mixing shifted toward the In‐rich side in the case of InGaAlN/GaN and toward the In‐poor side in the case of InGaAlN/InN compared with that of bulk In1–x–yGaxAlyN at x = 0, y = 0.5. This implies that lattice constraint from the bottom layer has a significant influence on thermodynamic stability of thin films. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of epitaxial layer crystal quality on DC and RF characteristics of AlGaN/GaN short‐gate HEMTs
Authors: Shiojima K. , Makimura T. , Maruyama T. , Suemitsu T. , Shigekawa N. , Hiroki M. , Yokoyama H.
Published: May 2006

The DC and RF performances of short‐gate AlGaN/GaN high‐electron transistors (HEMT) on SiC and sapphire substrates have been investigated. There were differences in surface morphology, electron mobility, and contact resistance between SiC and sapphire wafers. The contact resistance limited and dispersed measured transconductance (gm). The intrinsic gm after subtraction of the source resistance contribution and gate‐length dependences of cut‐off frequency were the same. These results indicates that the effective electron velocity is the same for both samples. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Low‐frequency noise in AlGaN/GaN HEMT structures with AlN thin film layer
Authors: Vitusevich S. A. , Antoniuk O. A. , Petrychuk M. V. , Danylyuk S. V. , Kurakin A. M. , Belyaev A. E. , Klein N.
Published: May 2006

Low‐frequency noise in AlGaN/GaN high electron mobility transistor (HEMT) heterostructures with additional AlN thin barrier layer is investigated. Transmission line model structures with different lengths of the conducting channel formed by polarization effects at the heterointerface of undoped AlGaN/AlN/GaN layers are studied. The measured noise demonstrates an unusual broadening of the generation‐recombination components of the spectra. To explain the noise behaviour of the structure we consider a model taking into account peculiarities of the band structure of the interface with inserted AlN high molar fraction barrier layer. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth of ternary and quaternary cubic III‐nitrides on 3C‐SiC substrates
Authors: Schörmann J. , Potthast S. , Schnietz M. , Li S. F. , As D. J. , Lischka K.
Published: May 2006

Cubic GaN, AlxGa1–xN/GaN multiple quantum wells and quaternary AlxGayIn1–x–yN layers were grown by plasma assisted molecular beam epitaxy on 3C‐SiC substrates. Using the intensity of a reflected high energy electron beam as a probe optimum growth conditions of c‐III nitrides were found, when a 1 monolayer Ga coverage is formed at the growing surface. Clear RHEED oscillations during the initial growth of AlxGa1–xN/GaN quantum wells were observed. X‐ray diffraction measurements of these quantum well structures show clear satellite peaks indicating smooth interfaces. Growth of quaternary AlxGayIn1–x–yN lattice matched to GaN were demonstrated. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
TEM analysis of annihilation process of threading dislocations in GaN thin films grown by MOVPE with anti‐surfactant treatment
Authors: Hijikuro M. , Kuwano N. , Takeuchi M. , Aoyagi Y.
Published: May 2006

Transmission electron microscope (TEM) observation was performed for the anti‐surfactant (AS) treated GaN layer in order to clarify the annihilation process of dislocations. The morphology of dislocations in 3‐dimension was analyzed in a stereographical way by using a high‐voltage TEM. It was revealed that most of the threading dislocations are laid down on the AS‐treated surface and merge with one another to form a network of dislocations (sweep‐up process). The dislocations then decrease in number after the merging by cancellation of their Burgers vectors. It was also revealed that a thin layer is formed on the AS‐treated surface. The layer was confirmed to be crystalline. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
InGaN quantum well epilayers morphological evolution under a wide range of MOCVD growth parameter sets
Authors: Florescu D. I. , Ting S. M. , Merai V. N. , Parekh A. , Lee D. S. , Armour E.A. , Quinn W. E.
Published: May 2006

This study exemplifies the use of TappingModeTM atomic force microscopy (AFM) surface morphology imaging to investigate and optimise the metalorganic chemical vapour deposition (MOCVD) growth conditions and post‐growth stability of thin (<40 Å) InGaN layers with direct implications to the structural and optical properties of blue (460 nm) and green (520 nm) LEDs. InGaN epilayers less than 40 Å thick of ∼20% solid phase indium were produced on thick (3‐4 µm) 2″ GaN templates grown on (0001) c ‐plane sapphire substrates. The morphological evolution of the InGaN material was studied utilising a DI3100 AFM tool. Surface morphology and its correlation with photoluminescence and X‐ray diffraction results will be discussed for every set of conditions employed. More specifically, the post‐growth ambient exposure and thermal stability of the uncapped InGaN epilayers were investigated. In addition, the initial stage of subsequent GaN growth, which is an essential step towards the manufacture of LED active regions, was examined. Based on the above findings, a flexible MOCVD growth parameter space and improved LED constituent layer sequencing techniques have been established leading to more efficient and stable LED devices. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Micro‐EL studying of high power blue LEDs
Authors: Onushkin G. A. , Zakgeim A. L. , Zakgeim D. A. , Rozhansky I. V. , Tsatsulnikov A. F. , Lundin W. V. , Sizov D. S.
Published: May 2006

The micro electro‐luminescence (EL) investigation of high‐power blue flip‐chip LEDs at high currents has been performed. The studied distribution of the spectral EL characteristics over the LED emitted area allowed evaluating the current crowding effect and revealed the local overheating of the p‐n junction. The current crowding effect lead to the two times higher local EL intensity. The local p‐n junction temperature distribution was calculated from FWHM map using obtained value a FWHM temperature coefficient. Maximum local junction temperature was by 50 K higher than average value over the LED area. The high local temperature and high local current density can lead to device failure or drastically decreases the LED lifetime. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of celery (Apium graveolens) extracts on some biochemical parameters of oxidative Stress in mice treated with carbon tetrachloride
Authors: Popović Mira , Kaurinović Biljana , Trivić Svetlana , Mimica‐Dukić Neda , Bursać Marija
Published: May 2006

Extracts of celery leaves and roots in ether, chloroform, ethyl acetate, n‐butanol and water were evaporated to dryness and dissolved in 50% ethanol to make 10% (w[sol ]v) solutions. The potential protective action of the extracts was assessed by the corresponding in vitro and in vivo tests. In the in vitro experiments crude methanol extracts were tested as potential scavengers of free OH• and DPPH• radicals, as well as inhibitors of liposomal peroxidation (LPx). Analogous experiments were also carried out with the extracts of celery root, for comparison. The results obtained show that both the extracts of root and leaves are good scavengers of OH• and DPPH• radicals and reduce LPx intensity in liposomes, which points to their protective (antioxidant) activity. In vivo experiments were concerned with antioxidant systems (activities of GSHPx, GSHR, Px, CAT, XOD, GSH content and intensity of LPx) in liver homogenate and blood of mice after their treatment with extracts of celery leaves, or in combination with CCl4. On the basis of the results obtained it can be concluded that the examined extracts showed a certain protective effect. Of all the extracts the n‐butanol extract showed the highest protective effect. Combined treatments with CCl4 and extracts showed both positive and negative synergism – inducing or suppressing the impact of CCl4 alone. The differences observed in the action of particular extracts are probably due to the different contents of flavonoids and some other antioxidant compounds. Copyright © 2006 John Wiley & Sons, Ltd.
Isolation of flavonoids, a biscoumarin and an amide from the flower buds of Daphne genkwa and the evaluation of their anti‐complement activity
Authors: Park Bo‐Young , Min Byung‐Sun , Oh Sei‐Ryang , Kim Jung‐Hee , Bae Ki‐Hwan , Lee Hyeong‐Kyu
Published: May 2006

As part of an ongoing study aimed at identifying the anti‐complement active compound from the flower buds of Daphne genkwa, ten flavonoids, one biscoumarin and one amide were isolated. Their structures were identified from spectroscopic and physicochemical data as genkwanin 5‐O‐β‐d‐primveroside (1), apigenin 7‐O‐β‐d‐glucuronide (2), genkwanin 5‐O‐β‐d‐glucopyranoside (3), apigenin 5‐O‐β‐d‐glucopyranoside (4), genkwanin (5), apigenin (6), luteolin 7‐methyl ether (7), luteolin (8), daphnoretin (9), velutin (10), 7‐methoxyacacetin (11) and aurantiamide acetate (12). Among them, compounds 9, 10 and 12 were isolated from this plant for the first time. The anti‐complement activity of these compounds was tested against the classical pathway of the complement system. Among the compounds, daphnoretin (9) exhibited significant anti‐complement activity with an IC50 value of 11.4 µm, whereas the other compounds were not active in the assay. Copyright © 2006 John Wiley & Sons, Ltd.
A component of BRAF‐HDAC complex, BHC80, is required for neonatal survival in mice
Authors: Iwase Shigeki , Shono Naomi , Honda Arata , Nakanishi Tomoko , Kashiwabara Shin-ichi , Takahashi Satoru , Baba Tadashi
Published: May 2006

BHC80 is a component of BRAF‐HDAC complex (BHC) involved in transcriptional repression of neuron‐specific genes in non‐neuronal cells. However, BHC80 is present in both neuronal and non‐neuronal cells. To explore the physiological importance of BHC80 in vivo, and the precise mechanism underlying neuron‐specific gene repression by BHC80, we have produced mutant mice lacking Bhc80. The loss of Bhc80 resulted in neonatal lethality without sucking mother's breast milk sufficiently. Although Bhc80‐deficient mice showed no developmental defect in the neuronal and non‐neuronal tissues, Bhc80 is indispensable for the survival of neonatal pups.
Public perceptions of non-governmental organisations in Serbia, Bosnia & Herzegovina, and Macedonia
Authors: Grødeland Åse Berit
Published: May 2006

The article examines the relationship between NGOs and the general public in Serbia, Bosnia & Herzegovina, and Macedonia. This relationship is often perceived as troubled. Focus group findings, however, suggest that ordinary people’s attitudes towards local NGOs are rather more nuanced and that quite a few people would like to join an NGO themselves, if given an opportunity. NGOs should therefore make more effort to tap into this potential, by providing more and better information about their activities available to the general public and by being more inclusive, thus enhancing both NGO legitimacy and future sustainability in the region.
Paul McCartney and the creation of ‘Yesterday’: the systems model in operation
Authors: MCINTYRE PHILLIP
Published: May 2006

By applying Mihaly Csikszentmihalyi's systems model of creativity, evidence can be presented to claim that despite ‘Yesterday’s promotion as a Romantic piece of creative activity, perpetuating the myth of the mystically inspired freely expressive artist, the creation of ‘Yesterday’ can be seen as a more considered and rational process than otherwise mythologised. The definition of creativity assumes an activity whereby products, processes and ideas are generated from antecedent conditions by the agency of someone, whose knowledge to do so comes from somewhere and the resultant novel variation is seen as a valued addition to the store of human knowledge. As an example of a system at work, the song's creation satisfies more closely the characteristics ascribed to the rationalist approach to creativity. From the evidence, it can be argued that creativity is a dynamic system that works on a larger scale than that of the sole individual posited by the Romantic conception and concomitant understandings. It, instead, incorporates the actions of the person, in this case Paul McCartney, within the systemic relationships of the field and domain. These three components, person, domain and field, comprise a system with circular causality where the individual, the social organisation they create within, and the symbol system they use are all equally important and interdependent in producing creative products. ‘Yesterday’ is but one creative product of this system at work.
Design Problem Solving
Authors: Winkelmann Constance , Hacker Winfried
Published: May 2006

Zusammenfassung. In zwei experimentellen Studien werden mögliche alternative Bedingungen der lösungsgüteverbessernden Wirkung einer Frage-Antwort-Technik im Entwurfsdenken (Design Problem Solving) geprüft. In der ersten Studie (N = 84) wurden differential- und kognitionspsychologische Bedingungen geprüft. Eine Aussagenanalyse in einer zweiten Studie (N = 94) sollte die nachgewiesenen Ergebnisse vertiefen. Für die in beiden Studien ermittelten Lösungsgüteverbesserungen konnten keine differentialpsychologischen Abhängigkeiten von Vorgehensstilen nachgewiesen werden. In kognitionspsychologischer Hinsicht zeigte sich, dass sowohl Fragen, die die Forderungen der Aufgabe in Erinnerung bringen, als auch Fragen, deren Beantwortung die Auslösung von Denkprozessen fördern, zur Lösungsgüteverbesserung beitragen. Größere Effekte werden bei der Kombination beider Fragenarten nahe gelegt. Die Ergebnisse der Aussagenanalyse weisen auf eine sowohl beschreibende als auch begründende und bewertende Vorgehensweise der Untersuchungsteilnehmer hin, die Verbesserungen erzielten. Fragen für weiterführende Untersuchungserfordernisse werden abgeleitet.
Melting a high 3He/4He source in a heterogeneous mantle
Authors: Ito Garrett , Mahoney John J.
Published: May 2006

Parameterized models of mantle flow and melting are used to examine two problems in ocean‐island and mid‐ocean ridge basalt (OIB, MORB) geochemistry: (1) the causes of variations in He, Sr, Nd, and Pb isotopes with one another and with age of the surrounding seafloor and (2) the origin of geochemical distinctions between OIB and MORB. We assume the mantle is a mixture of different isotopic components that have different solidus temperatures and are expressed in magmas to varying degrees depending on mantle temperature, lithospheric thickness, and shallow mantle flow. Isotopic variations along the Hawaiian hot spot chain support the possibility that lithospheric thickness controls magma composition primarily by limiting the melting of the most refractory, depleted mantle (DM) component. For Hawaii and a collection of other hot spots, calculations of melt extraction trajectories reproduce the strong correlations often seen among Sr‐Nd‐Pb isotopes together with the more variable and weaker correlations involving 3He/4He. The latter are predicted to be a direct consequence of only one mantle component with high 3He/4He. We show that both OIB and MORB can arise out of the same heterogeneous mantle layer if three conditions are met: the high‐3He/4He source begins melting deeper than DM, DM is ≥85% of the mantle, and the concentration of He in the high‐3He/4He source is comparable to that in DM.
Spiking modular neural networks: A neural network modeling approach for hydrological processes
Authors: Parasuraman Kamban , Elshorbagy Amin , Carey Sean K.
Published: May 2006

Artificial Neural Networks (ANNs) have been widely used for modeling hydrological processes that are embedded with high nonlinearity in both spatial and temporal scales. The input‐output functional relationship does not remain the same over the entire modeling domain, varying at different spatial and temporal scales. In this study, a novel neural network model called the spiking modular neural networks (SMNNs) is proposed. An SMNN consists of an input layer, a spiking layer, and an associator neural network layer. The modular nature of the SMNN helps in finding domain‐dependent relationships. The performance of the model is evaluated using two distinct case studies. The first case study is that of streamflow modeling, and the second case study involves modeling of eddy covariance‐measured evapotranspiration. Two variants of SMNNs were analyzed in this study. The first variant employs a competitive layer as the spiking layer, and the second variant employs a self‐organizing map as the spiking layer. The performance of SMNNs is compared to that of a regular feed forward neural network (FFNN) model. Results from the study demonstrate that SMNNs performed better than FFNNs for both the case studies. Results from partitioning analysis reveal that, compared to FFNNs, SMNNs are effective in capturing the dynamics of high flows. In modeling evapotranspiration, it is found that net radiation and ground temperature alone can be used to model the evaporation flux effectively. The SMNNs are shown to be effective in discretizing the complex mapping space into simpler domains that can be learned with relative ease.
Is the uniform electron gas limit important for small Ag clusters? Assessment of different density functionals for Agn (n⩽4)
Authors: Zhao Shuang , Li Zhen-Hua , Wang Wen-Ning , Liu Zhi-Pan , Fan Kang-Nian , Xie Yaoming , Schaefer Henry F.
Published: May 2006

Twenty-three density functional theory (DFT) methods, including the second- and the third-generation functionals, are tested in conjunction with two basis sets (LANL2DZ and SDD) for studying the properties of neutral and ionic silver clusters. We find that DFT methods incorporating the uniform electron gas limit in the correlation functional, namely, those with Perdew’s correlation functionals (PW91, PBE, P86, and TPSS), Becke’s B95, and the Van Voorhis-Scuseria functional VSXC, generally perform better than the other group of functionals, e.g., those incorporating the LYP correlation functional and variations of the B97 functional. Strikingly, these two groups of functionals can produce qualitatively different results for the Ag3 and Ag4 clusters. The energetic properties and vibrational frequencies of Agn are also evaluated by the different functionals. The present study shows that the choice of DFT methods for heavy metals may be critical. It is found that the exact-exchange-incorporated PBE functional (PBE1PBE) is among the best for predicting the range of properties.
Magnetic properties and microstructures of FePt∕Ti bilayer films sputter deposited onto glass amorphous substrates
Authors: Sun H. Y. , Xu J. L. , Feng S. Z. , Su Z. F. , Hu J. , Sun Y. P.
Published: May 2006

FePt ∕ Ti granular films were fabricated onto glass amorphous substrates using a dc facing-target magnetron sputtering system at various Ti underlayer thickness, then annealed at temperature Ta ranging from 200 to 700°C. In the FePt(30nm)∕Ti(1nm) film annealed at 600°C, the coercivity about 12kOe is obtained. The results of x-ray diffraction indicate that a ternary FePtTi alloy is formed. Thus, the formation of the ternary FePtTi alloy is considered to play an important role in magnetic properties.
Rapid solidification of highly undercooled Si and Si–Co melts
Authors: Panofen C. , Herlach D. M.
Published: May 2006

We present direct experimental observations of growth velocity and morphology in undercooled melts of pure Si and dilute Si100−xCox alloys (x=0.1, 0.5, and 2.5at.%). An anomalous behavior in the growth velocity-undercooling relation of the Si–Co alloys is found, exhibiting an abrupt break at a critical undercooling ΔT* which depends on Co concentration. In contrast to pure Si, the anomalous growth behavior in Si–Co alloys cannot be described by current dendrite growth theory even if nonequilibrium effects at the interface as solute trapping are taken into account. The growth morphology changes essentially with increasing undercooling and Co concentration.
Carrier-mediated ferromagnetism in vanadium-doped (Sb1−xBix)2Te3 solid solutions
Authors: Zhou Zhenhua , Uher Ctirad , Zabcik Marek , Lostak Petr
Published: May 2006

Ferromagnetism in tetradymite-type diluted magnetic semiconductors (Sb1−xBix)1.98V0.02Te3 (0⩽x⩽1) is revealed to be of hole-mediated nature. The increasing replacement of antimony with bismuth results in a monotonous decrease of the hole concentration and the Curie temperature while the electrical resistivity increases. The value of the Curie temperature shows a linear dependence of Np1∕3, where N is the vanadium concentration and p is the concentration of hole. This trend agrees with the mean-field theory predictions.
Investigation of Pd∕Ti∕Al and Ti∕Al Ohmic contact materials on Ga-face and N-face surfaces of n-type GaN
Authors: Jang T. , Lee S. N. , Nam O. H. , Park Y.
Published: May 2006

Pd ∕ Ti ∕ Al and Ti∕Al Ohmic contact materials on Ga-face and N-face surfaces of n-type GaN were investigated by measuring the contact resistivities with respect to annealing temperatures. Pd∕Ti∕Al contact showed good Ohmic property in contrast to Ti∕Al contact on N-face surface of n-type GaN. Cross-sectional transmission electron microscopy results on samples of as-deposited and annealed at 450°C for 30s indicated that Pd played an important role in changing the surface state of N-face surface of n-type GaN and less than 50Å of Pd was required to obtain the best Ohmic contact property.
Luminescence from Nd- and Dy-ion-implanted 4H–SiC
Authors: Kawai Shinji , Masaki Takayoshi , Kato Yoshimine , Motooka Teruaki
Published: May 2006

Cathodoluminescence (CL) and photoluminescence (PL) properties are studied on neodymium (Nd)- and dysprosium (Dy)-ion-implanted 4H–SiC. No appreciable CL and PL can be observed for all as-implanted samples. Strong visible CL due to Nd3+ and Dy3+ is observed only after rapid thermal annealing at 1500°C followed by thermal oxidations at 860°C for 720min. On the other hand, near infrared PL is observed only from Nd-implanted 4H–SiC without thermal oxidation. It is found from the CL spectra observed after thermal oxidation that the ligand field effects on Nd3+ are strong, while those on Dy3+ are weak.
Effect of nitrogen incorporation on the electronic structure and thermal stability of HfO2 gate dielectric
Authors: Wang S. J. , Chai J. W. , Dong Y. F. , Feng Y. P. , Sutanto N. , Pan J. S. , Huan A. C. H.
Published: May 2006

The effect of nitrogen incorporation on the electronic structure and thermal stability of HfO2 gate dielectric was investigated by using photoemission study and first-principles calculation. Hafnium oxynitride (HfON) dielectric shows higher thermal stability in comparison to pure HfO2 on Si. Atomic N can passivate O vacancies in the dielectrics during nitridation process, but the N atoms incorporated into interstitial sites cause band gap reduction. Postnitridation annealing is required to activate interstitial N atoms to form stable N–Hf bonds, which will increase the band gap and band offset of as-nitrided dielectric film.
The mechanism of superoxide production by NADH:ubiquinone oxidoreductase (complex I) from bovine heart mitochondria
Authors: Kussmaul Lothar , Hirst Judy
Published: May 2006

NADH:ubiquinone oxidoreductase (complex I) is a major source of reactive oxygen species in mitochondria and a significant contributor to cellular oxidative stress. Here, we describe the kinetic and molecular mechanism of superoxide production by complex I isolated from bovine heart mitochondria and confirm that it produces predominantly superoxide, not hydrogen peroxide. Redox titrations and electron paramagnetic resonance spectroscopy exclude the iron-sulfur clusters and flavin radical as the source of superoxide, and, in the absence of a proton motive force, superoxide formation is not enhanced during turnover. Therefore, superoxide is formed by the transfer of one electron from fully reduced flavin to O
2
. The resulting flavin radical is unstable, so the remaining electron is probably redistributed to the iron-sulfur centers. The rate of superoxide production is determined by a bimolecular reaction between O
2
and reduced flavin in an empty active site. The proportion of the flavin that is thus competent for reaction is set by a preequilibrium, determined by the dissociation constants of NADH and NAD
+
, and the reduction potentials of the flavin and NAD
+
. Consequently, the ratio and concentrations of NADH and NAD
+
determine the rate of superoxide formation. This result clearly links our mechanism for the isolated enzyme to studies on intact mitochondria, in which superoxide production is enhanced when the NAD
+
pool is reduced. Therefore, our mechanism forms a foundation for formulating causative connections between complex I defects and pathological effects.
A likelihood approach to analysis of network data
Authors: Wiuf Carsten , Brameier Markus , Hagberg Oskar , Stumpf Michael P. H.
Published: May 2006

Biological, sociological, and technological network data are often analyzed by using simple summary statistics, such as the observed degree distribution, and nonparametric bootstrap procedures to provide an adequate null distribution for testing hypotheses about the network. In this article we present a full-likelihood approach that allows us to estimate parameters for general models of network growth that can be expressed in terms of recursion relations. To handle larger networks we have developed an importance sampling scheme that allows us to approximate the likelihood and draw inference about the network and how it has been generated, estimate the parameters in the model, and perform parametric bootstrap analysis of network data. We illustrate the power of this approach by estimating growth parameters for theCaenorhabditis elegansprotein interaction network.
Purkinje neuron degeneration in nervous (
nr
) mutant mice is mediated by a metabolic pathway involving excess tissue plasminogen activator
Authors: Li Jianxue , Ma Yinghua , Teng Yang D. , Zheng Kangni , Vartanian Timothy K. , Snyder Evan Y. , Sidman Richard L.
Published: May 2006

Purkinje neurons (PNs), the central cells in cerebellar circuitry and function, constitute a vulnerable population in many human genetic, malignant, hypoxic, and toxic diseases. In the nervous (
nr
) mutant mouse, the majority of PNs die in the fourth to fifth postnatal weeks, but the responsible molecules are unknown. We first disclose a remarkable increase in mRNA expression and protein concentration in the
nr
cerebellum of tissue plasminogen activator (tPA), a gene closely linked to the mapped but as-yet-uncloned
nr
locus. Evidence that excessive tPA triggers
nr
PN death was obtained with organotypic slice cultures expressing the
nr
PN phenotype, in which an inhibitor of tPA led to increased
nr
PN survival. An antagonist of protein kinase C, a downstream component in the tPA pathway, also increased
nr
PN survival. Additional downstream targets in the tPA pathway (the mitochondrial voltage-dependent anion channel, brain-derived neurotrophic factor, and neurotrophin 3) were also abnormal, in parallel with the alterations in PN mitochondrial morphology, dendritic growth, and synaptogenesis that culminate in
nr
PN death and motor incoordination. We thus propose a molecular pathway by which the excessive tPA in
nr
cerebellum mediates PN degeneration.
Neurons produce type I interferon during viral encephalitis
Authors: Delhaye Sophie , Paul Sophie , Blakqori Gjon , Minet Muriel , Weber Friedemann , Staeheli Peter , Michiels Thomas
Published: May 2006

Type I interferons, also referred to as IFN-α/β, form the first line of defense against viral infections. Major IFN-α/β producers in the periphery are the plasmacytoid dendritic cells (pDCs). Constitutive expression of the IFN regulatory factor (IRF)-7 enables pDCs to rapidly synthesize large amounts of IFN-α/β after viral infection. In the central nervous system (CNS), pDCs are considered to be absent from the parenchyma, and little is known about the cells producing IFN-α/β. The study presented here aimed to identify the cells producing IFN-α/β in the CNS
in vivo
after infection by neurotropic viruses such as Theiler's virus and La Crosse virus. No cells with high constitutive expression of IRF-7 were detected in the CNS of uninfected mice, suggesting the absence of cells equivalent to pDCs. Upon viral infection, IFN-β and some subtypes of IFN-α, but not IFN-ε or IFN-κ, were transcriptionally up-regulated. IFN-α/β was predominantly produced by scattered parenchymal cells and much less by cells of inflammatory foci. Interestingly, in addition to some macrophages and ependymal cells, neurons turned out to be important producers of both IFN-α and IFN-β. However, only 3% of the infected neurons produced IFN-α/β, suggesting that some restriction to IFN-α/β production existed in these cells. All CNS cell types analyzed, including neurons, were able to respond to type I IFN by producing Mx or IRF-7. Our data show that,
in vivo
, neurons take an active part to the antiviral defense by being both IFN-α/β producers and responders.
Multiorgan engraftment and differentiation of human cord blood CD34
+
Lin
−
cells in goats assessed by gene expression profiling
Authors: Zeng Fanyi , Chen Mei-jue , Baldwin Don A. , Gong Zhi-juan , Yan Jing-bin , Qian Hui , Wang Juan , Jiang Xiaoyan , Ren Zhao-rui , Sun Deming , Huang Shu-zhen
Published: May 2006

To investigate multitissue engraftment of human primitive hematopoietic cells and their differentiation in goats, human CD34
+
Lin
−
cord blood cells transduced with a GFP vector were transplanted into fetal goats at 45–55 days of gestation. GFP
+
cells were detected in hematopoietic and nonhematopoietic organs including blood, bone marrow, spleen, liver, kidney, muscle, lung, and heart of the recipient goats (1.2–36% of all cells examined). We identified human β2 microglobulin-positive cells in multiple tissues. GFP
+
cells sorted from the perfused liver of a transplant goat showed human insulin-like growth factor 1 gene sequences, indicating that the engrafted GFP
+
cells were of human origin. A substantial fraction of cells engrafted in goat livers expressed the human hepatocyte-specific antigen, proliferating cell nuclear antigen, albumin, hepatocyte nuclear factor, and GFP. DNA content analysis showed no evidence for cellular fusion. Long-term engraftment of GFP
+
cells could be detected in the blood of goats for up to 2 yr. Microarray analysis indicated that human genes from a variety of functional categories were expressed in chimeric livers and blood. The human/goat xenotransplant model provides a unique system to study the kinetics of hematopoietic stem cell engraftment, gene expression, and possible stem cell plasticity under noninjured conditions.
Relationship between individual DNA methylation percentage differences and carcass traits in pigs
Authors: Cao-De Jiang , Chang-Yan Deng , Yuan-Zhu Xiong
Published: May 2006

In order to investigate the effects of DNA methylation on pig carcass traits, the methylation-sensitive amplified polymorphism technique (MSAP) was adopted to amplify DNA from blood samples taken from 77 F1hybrids of Large White×Meishan crosses. A total of 15 carcass traits were tested. Results showed that means of internal fat rate (IFR), lean meat percentage (LMP) and ratio of lean meat versus fat meat (RLF) were significantly different (P<0.05) among five levels of general individual methylation difference (GIMDP); means of carcass weight (CW), IFR, backfat thickness at buttock (BFT3), average backfat thickness (ABF), carcass length to the first rib (CLR) and carcass length to the first neck vertebra (CLN) were also significantly different (P<0.05) among five levels of special individual methylation percentage difference (SIMDP), while means of 15 carcass traits were not significantly different (P>0.05) among five levels of neutral individual methylation percentage difference (NIMDP). Of all traits that were significantly affected by SIMPD, CW, ABF and BFT3increased, IFR and backfat thickness at shoulder (BFT1) decreased, while CLR and bone percentage (BP) fluctuated with the SIMDP increase. The regressions between SIMDP and IFR, BFT1, BFT3and ABF were significant (P<0.05). It is concluded that DNA methylation can be applied as a marker to related studies in pigs; positive methylation sites were superior to negative methylation sites in predicting hybrid performance, and methylation differences should be maintained at specific levels for different traits to improve the productivity of pigs.
An association between tyrosinase gene single nucleotide polymorphisms and melanin distribution in chicken
Authors: Zhi-Qiang Chen , Xue-Mei Deng , Jun Zhou , Ning Li , Chang-Xin Wu
Published: May 2006

Tyrosinase (TYR) is a key enzyme of melanin biosynthesis. Single-strand conformation polymorphism (SSCP) analysis was applied to detect the single nucleotide polymorphisms (SNPs) in the upstream regulating region from -641 to -2125 bp of the TYR gene. Three SNPs were found in this region. Correlations were obtained between genotypes of the SNP sites and pigment traits in chicken parental and F2 generations of the Chinese Agricultural University (CAU) resource population. The chi-square test indicated that these mutations were significantly related to shank and body skin colours.