bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantum tunnelling and decoherence in nanomagnets
Authors: Gedik Z. , Bozat Ö. 
Published: January 2006

AbstractStarting from the observation that at very low temperatures an isolated nanomagnet can be treated as an effective two‐state system, we introduce a model to study quantum tunnelling and decoherence phenomena. We assume that the total spin of the magnet interacts with a spin bath. We show that depending upon the interaction strengths the molecule can exhibit tunnelling with or without decoherence. We also investigate the case where the spin‐spin interaction is mediated by phonons. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magnetic behaviour of iron nanoparticles passivated by oxidation
Authors: Can Musa Mutlu , Özcan Şadan , Fırat Tezer 
Published: January 2006

AbstractThis study is to understand the effect of oxidation, especially magnetically, on iron nanoparticles. According to generation of the oxidated iron nanoparticles, mechanical alloying technique was used and nanosized magnetite (Fe3O4), maghemite (γ‐Fe2O3) and hematite (α‐Fe2O3) particles were obtained as the resultant samples. The reactance to the thermal treatment was determined by differential thermal analysis and thermogravimetric (DTA‐TG) measurements. X‐ray powder diffractions (XRD) helped to exhibit the structure of the sample by ICDD cards and to determine the size of nanoparticles by using the Scherrer formula. On the other hand, VSM (vibrating sample magnetometer) measurements were determined to understand the magnetic behaviour. Through the transformation of Fe3O4 to other iron‐oxides, two exothermic peaks were observed at around 169.11 °C and 562.61 °C by DTA analysis. Beside of this, the experimental results demonstrate the effects of mechanical milling parameters, atmosphere and lubricant, to the structure and to the size of the resultant particles and the change of magnetic behavior of the iron‐oxide and iron nanoparticles when they approach to superparamagnetic region, especially in single domain region. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spin current in spin‐triplet superconducting nanostructures
Authors: Asano Yasuhiro 
Published: January 2006

AbstractWe derive the spin current formula in superconductors on the basis of the mean‐field theory of superconductivity. The obtained formula is applied to mesoscopic p ‐wave superconducting rings. We discuss a possibility of the circulating spin current in p ‐wave superconducting rings at the zero magnetic field. The direction of spin current depends on topological numbers which characterize the spatial configuration of the spin vector of Cooper pairs. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Characterization of (Co0.45Fe0.45Zr0.10)x(Al2O3)1–x nanocomposite films applicable as spintronic materials
Authors: Saad A.M. , Fedotov A.K. , Fedotova J.A. , Svito I.A. , Andrievsky B.V. , Kalinin Yu.E. , Fedotova V.V. , Malyutina‐Bronskaya V. , Patryn A.A. , Mazanik A.V. , Sitnikov A.V. 
Published: January 2006

AbstractThe combined use of scanning electron microscopy, Mössbauer spectrometry, X‐ray diffraction and also DC/AC electrical and magnetic characterization techniques allowed this work to elucidate the influence of metal‐to‐dielectric component ration, and effect of oxygen in gas mixture on phase structure and properties of the Co0.45Fe0.45Zr0.10 ferromagnetic nanoparticles in amorphous dielectric Al2O3 matrix. The films of 3–5 µm thickness with compositions of 30 at.% < X < 60 at.% were sputtered on a single substrate from the compound target in the chamber containing either pure Ar or Ar‐O gas mixture. The films sputtered in Ar‐O mixture resulted in partial oxidation of metallic nanoparticles causing the shift of percolation threshold X c to 55 at.% as compared to 45–47 at.% for the samples deposited in pure Ar. Mössbauer studies of the films sputtered in Ar gas have shown that at X < X c metallic nanoparticles were at superparamagnetic state but for X > X c metallic phase showed a ferromagnetic behavior. DC carrier transport at the temperatures of 77–350 K were explained by hopping mechanisms and described by Mott and Shklowski‐Efros laws. That was also confirmed by the relationship power law of Z ′(f ) ∼ f –s (s ≤ 2) for real part of impedance at low temperatures (<120 K) for the samples on dielectric side of MIT. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Off‐resonance Raman spectroscopy of Cd1–xMnxS nanoparticles
Authors: Romčević N. , Kostić R. , Romčević M. 
Published: January 2006

AbstractCd1–xMnxS nanoparticles (NPs) with average radius Ro = 2.2 nm have been investigated by Raman scattering measurements. The nanoparticles, synthesized using aqueous solution precipitation, are small enough to show effects due to confinement. The dominant line was at about 300 cm–1 having asymmetric broadening for ω < 300 cm–1. Significant change in intensity for different x and excitation energies was noticed. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Microstructural study and size control of iron oxide nanoparticles produced by microemulsion technique
Authors: Koutzarova T. , Kolev S. , Ghelev Ch. , Paneva D. , Nedkov I. 
Published: January 2006

AbstractIn this paper we study the possibility to control the size of iron oxide (Fe3O4) nanoparticles by the microemulsion technique. We used a water‐in‐oil reverse microemulsion system with n‐hexadecil trimethylammonium bromide (CTAB) as a cationic surfactant, n‐butanol as a co‐surfactant, n‐hexanol as a continuous oil phase, and aqueous phase. The magnetite nanopowders were synthesized by a single microemulsion technique in which the aqueous phase contains only metal ions (Fe2+ and Fe3+). The particle size of the powders varied in the range of 14–36 nm depending on the preparation conditions. We studied the influence of changing the water/surfactant ratio (W 0 = 5, 10, 15, 20) and the metallic ion (Fe2+ and Fe3+) concentration on the particle size distribution and crystallinity of Fe3O4. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Microwave absorption of ferrite powders in a polymer matrix
Authors: Kolev S. , Yanev A. , Nedkov I. 
Published: January 2006

AbstractThe object of this work is to investigate the microwave absorbing properties of nanocomposite bulk samples. As filler we used magnetite with different particle size in a silicone rubber matrix and investigated the influence of the filler concentration and particle size in the polymer matrix on the microwave nonlinearity in a large frequency range (1 ÷ 13 GHz). We found that the intensity and the frequency at the reflection loss minimum depend on the particle size and particle concentration of magnetite in the samples. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Temperature‐induced changes of domain structures in ultrathin magnetic films
Authors: Polyakova T. , Zablotskii V. 
Published: January 2006

AbstractWe describe the thermal‐driven evolution of stripe domain structures in ultrathin magnetic films with perpendicular anisotropy. Taking into account temperature dependencies of the film magnetic parameters we analyze possible temperature dependencies of the domain period. It is shown that the film heating leads to a decrease in the domain period. In soft films thermally assisted domain nucleation could provide a continuous decrease of the domain period while the domain structure passes through equilibrium states. On increasing the temperature of a hard film, the domain structure exists as metastable one adjusting its period by a sequence of jumps towards to equilibrium. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Imaging of inhomogeneous magnetization and currents coupled with anomalous transport properties in manganites
Authors: Tokunaga M. , Song H. , Tokunaga Y. , Tamegai T. 
Published: January 2006

AbstractUsing magneto‐optical imaging technique, real‐space distributions of magnetic fields are visualized in images of a polarized‐light microscope. Application of this technique to crystals of (La1–z Prz )0.7Ca0.3MnO3 (z = 0.7) and Nd0.5Ca0.5Mn1–y Cry O3 (y = 0.03) revealed inhomogeneous magnetization and currents in the phase‐separated states into ferromagnetic metal and antiferromagnetic insulator. Increase of the transport current switches this inhomogeneous current flow to homogeneous one concomitantly with abrupt increase in resistivity. Using magnetic field dependence of this switching phenomenon, operation fields for colossal magnetoresistance effects can be significantly reduced. Empirical relation between the magnitude of bias currents and transition fields is provided. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Equilibrium and metastable nanoscale domains in ultrathin magnets
Authors: Kisielewski M. , Maziewski A. , Polyakova T. , Zablotskii V. 
Published: January 2006

AbstractWe describe equilibrium and nonequilibrium stripe domains in ultrathin magnetic films with uniaxial perpendicular anisotropy. The notion of the domain chemical potential is introduced to analyze metastable domains and their thermal and field evolution. For ultrathin cobalt films the domain period is calculated as a function of the coercivity field. We demonstrate that the period of metastable domains can significantly differ from the period of equilibrium domains. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Different catalysis role of in‐loop and out‐of‐loop waters in assisting HNS/HSN proton transfer isomerizations: Bridging vs. surrounding effect
Authors: Yin Wenjuan , Yan Shihai , Qin Mei , Li Zhiqiang , Bu Yuxiang 
Published: January 2006

AbstractIn this work, a density function theory (DFT) study is presented for the HNS/HSN isomerization assisted by 1–4 water molecules on the singlet state potential energy surface (PES). Two modes are considered to model the catalytic effect of these water molecules: (i) water molecule(s) participate directly in forming a proton transfer loop with HNS/HSN species, and (ii) water molecules are out of loop (referred to as out‐of‐loop waters) to assist the proton transfer. In the first mode, for the monohydration mechanism, the heat of reaction is 21.55 kcal · mol−1 at the B3LYP/6‐311++G** level. The corresponding forward/backward barrier lowerings are obtained as 24.41/24.32 kcal · mol−1 compared with the no‐water‐assisting isomerization barrier T (65.52/43.87 kcal · mol−1). But when adding one water molecule on the HNS, there is another special proton‐transfer isomerization pathway with a transition state 10T′ in which the water is out of the proton transfer loop. The corresponding forward/backward barriers are 65.89/65.89 kcal · mol−1. Clearly, this process is more difficult to follow than the R–T–P process. For the two‐water‐assisting mechanism, the heat of reaction is 19.61 kcal · mol−1, and the forward/backward barriers are 32.27/12.66 kcal · mol−1, decreased by 33.25/31.21 kcal · mol−1 compared with T. For trihydration and tetrahydration, the forward/backward barriers decrease as 32.00/12.60 (30T) and 37.38/17.26 (40T) kcal · mol−1, and the heat of reaction decreases by 19.39 and 19.23 kcal · mol−1, compared with T, respectively. But, when four water molecules are involved in the reactant loop, the corresponding energy aspects increase compared with those of the trihydration. The forward/backward barriers are increased by 5.38 and 4.66 kcal · mol−1 than the trihydration situation. In the second mode, the outer‐sphere water effect from the other water molecules directly H‐bonded to the loop is considered. When one to three water molecules attach to the looped water in one‐water in‐loop‐assisting proton transfer isomerization, their effects on the three energies are small, and the deviations are not more than 3 kcal · mol−1 compared with the original monohydration‐assisting case. When adding one or two water molecules on the dihydration‐assisting mechanism, and increasing one water molecule on the trihydration, the corresponding energies also are not obviously changed. The results indicate that the forward/backward barriers for the three in‐loop water‐assisting case are the lowest, and the surrounding water molecules (out‐of‐loop) yield only a small effect. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Isolation and characterization of promoters suitable for a multidrug‐resistant marker CuYAP1 in the yeast Candida utilis
Authors: Iwakiri Ryo , Noda Yoichi , Adachi Hiroyuki , Yoda Koji 
Published: January 2006

AbstractThe overexpression of CuYAP1 by the CuGAP1 promoter (Pgap) was recently shown to function as a drug‐resistant selection marker for the industrially important yeast Candida utilis. In order to increase the efficiency of selection, we screened for promoters better than Pgap to express CuYAP1. Two restriction fragments, P2‐1‐2 (0.5 kbp) and P2‐33‐2 (1.4 kbp), gave higher cycloheximide resistance, and five‐ to 10‐fold of the transformants were selectable by using these fragments. These promoters were found to be at the 5′ of the ribosomal protein genes, RPL31 and RPL29, respectively. Interestingly, their transcription activity was less than one‐tenth that of Pgap in the absence of cycloheximide. The transcription also increased by the addition of blasticidin S or hygromycin B and heat shock. These novel characteristics will be suitable for an economical marker of the recombinant cell. The DDBJ/EMBL/GenBank Accession Nos. for P2‐1, P2‐33‐2, RPL31 and RPL29 are AB206952, AB206953, AB208646 and AB208647, respectively. Copyright © 2006 John Wiley & Sons, Ltd.
Spsgt1, a new essential gene of Schizosaccharomyces pombe, is involved in carbohydrate metabolism
Authors: Kainou Tomohiro , Shinzato Tomoko , Sasaki Kentaro , Mitsui Youji , Giga‐Hama Yuko , Kumagai Hiromichi , Uemura Hiroshi 
Published: January 2006

AbstracthSGT1 (human suppressor of Gcr two) was isolated as a suppressor gene of the gcr2 mutation. Since Gcr2p is a key regulatory factor of glycolytic gene expression in Saccharomyces cerevisiae, hSGT1 is a candidate for a novel human transcription factor involved in carbohydrate metabolism. SGT1 appears to be conserved from Schizosaccharomyces pombe to human but not present in S. cerevisiae. To further study its function, we cloned the hSgt1p orthologue of Sz. pombe (Spsgt1) from Sz. pombe genomic DNA. Overall identity and similarity between SpSgt1p and hSgt1p are 24% and 37%, respectively. Disruption of Spsgt1 showed that Spsgt1 is essential for growth and, using a construct which conditionally expresses sgt1, which with low level expression growth was severely affected on glucose but normal on non‐fermentable carbon sources. DNA microarray analyses showed that the transcription of many genes involved in carbohydrate metabolism and amino acid metabolism were upregulated in the mutant, suggesting that SpSgt1p may be involved in the regulation of carbohydrate metabolism. Furthermore, a GFP fusion of SpSgt1p was localized to the nucleus, fitting with the possibility of SpSgt1p as a transcription factor. Copyright © 2006 John Wiley & Sons, Ltd.
Enzymes of UDP‐GlcNAc biosynthesis in yeast
Authors: Milewski Sławomir , Gabriel Iwona , Olchowy Jarosław 
Published: January 2006

AbstractD‐Glucosamine is an important building block of major structural components of the fungal cell wall, namely chitin, chitosan and mannoproteins. Other amino sugars, such as D‐mannosamine and D‐galactosamine, relatively abundant in higher eukaryotes, rarely occur in fungal cells and are actually absent from yeast and yeast‐like fungi. The glucosamine‐containing sugar nucleotide UDP‐GlcNAc is synthesized in yeast cells in a four‐step cytoplasmic pathway. This article provides a comprehensive overview of the present knowledge on the enzymes catalysing the particular steps of the pathway in Candida albicans and Saccharomyces cerevisiae, with a special emphasis put on mechanisms of the catalysed reactions, regulation of activity and perspectives for exploitation of enzymes participating in UDP‐GlcNAc biosynthesis as potential targets for antifungal chemotherapy. Copyright © 2006 John Wiley & Sons, Ltd.
A truncated derivative of nmt1 promoter exhibits temperature‐dependent induction of gene expression in Schizosaccharomyces pombe
Authors: Kumar Raj , Singh Jagmohan 
Published: January 2006

AbstractDespite increasing exploitation of Schizosaccharomyces pombe as a model system there is a lack of convenient vectors for research and application. Expression with the commonly used promoter, nmt1, requires a laborious regime involving the removal of repressor, thiamine, from a growing culture and further growth for 18 h to achieve maximum expression, thus underlining the need for more user‐friendly promoters. We report here the isolation and characterization of a truncated derivative of the nmt1 promoter having novel induction characteristics: it is induced by shift of growth temperature from 36 °C to 25 °C, achieving maximum expression within 3 h. Similar features of expression were observed with the reporter genes GFP and β‐galactosidase, a native gene, cdc18, and a commercially important foreign therapeutic protein, streptokinase. The new promoter element offers additional advantages, such as lack of deleterious effect on cell viability and potential ability to express toxic proteins. These features make the new promoter a potentially better alternative to nmt1, both as a research tool and for expression of commercially important proteins in Sz. pombe, and suggest the possibility of using similar approaches to design promoters with novel and useful properties. Copyright © 2006 John Wiley & Sons, Ltd.
Usefulness of Multidetector Computed Tomography for the Initial Assessment of Blunt Abdominal Trauma Patients
Authors: Fang Jen‐Feng , Wong Yon‐Cheong , Lin Being‐Chuan , Hsu Yu‐Pao , Chen Miin‐Fu 
Published: January 2006

AbstractBackgroundThe prompt detection and accurate localization of abdominal injuries are difficult. Some diagnostic modalities, including laboratory tests, ultrasound, and diagnostic peritoneal lavage (DPL) were used to evaluate patients with blunt abdominal trauma, with various advantages and pitfalls. We aimed to evaluate the risk and benefit of using multidetector computed tomography (MDCT) as an initial assessment tool for proper diagnosis and treatment planning of patients with blunt abdominal trauma.MethodsTwo hundred fifty‐two patients with blunt abdominal trauma were prospectively enrolled. Multidetector computed tomography was performed during resuscitation. The risk and benefit of using MDCT in the diagnosis and planning of treatment were analyzed.ResultsThe time required for a MDCT examination averaged 10.2 minutes. Of the studies done, 224 revealed abdominal injuries. Of those, 34 were performed in patients with unstable hemodynamic status without adverse effect. Prompt diagnosis and proper treatment were given according to the MDCT findings. A total of 43 (17.1%) MDCTs showed contrast extravasation. Active bleeding was confirmed in all and treated with transarterial embolization (30) or surgery (13). Another 58 patients sustained bowel, mesenteric, or pancreatic injuries (BMPI) necessitating laparotomy. The sensitivity, specificity, and accuracy of MDCT in identifying patients with active bleeding or BMPI were all 100%.ConclusionsMultidetector computed tomography was useful as a second line initial assessment tool to identify injuries and determine treatment planning in blunt abdominal trauma patients. No increased risk was found if the facility is readily available, the protocol is well designed, and the patient is well prepared.
Prognostic Significance of Extrathyroid Extension of Papillary Thyroid Carcinoma: Massive but Not Minimal Extension Affects the Relapse‐free Survival
Authors: Ito Yasuhiro , Tomoda Chisato , Uruno Takashi , Takamura Yuuki , Miya Akihiro , Kobayashi Kaoru , Matsuzuka Fumio , Kuma Kanji , Miyauchi Akira 
Published: January 2006

AbstractObjectivesExtrathyroid extension has been recognized as a prognostic factor in papillary thyroid carcinoma. In the most recent version of the UICC TNM classification system, extrathyroid extension has been classified into two grades, minimal extension (extension to sternothyroid muscle or perithyroid soft tissues) and massive extension (extension to subcutaneous soft tissue, larynx, trachea, esophagus, or recurrent laryngeal nerve). In this study, we investigated the prognostic significance of each of the two types of extension.Patients and MethodsOne thousand and sixty‐seven patients with papillary thyroid carcinoma without distant metastasis at surgery, who underwent surgical treatment in Kuma hospital between 1990 and 1995 and had been followed postoperatively for 60 months or more, were enrolled in this study. The grading of extrathyroid extension was based on both pathological findings and intraoperative surgical findings.ResultsIn univariate analysis, although patients with massive extension showed a significantly worse relapse‐free survival (RFS) rate than those with no or minimal extension (P < 0.0001), there was no difference in the RFS rate between patients with no extension and those with minimal extension. Among patients with massive extension, the RFS rate tended to be worse in those with posterior extension than in those with anterior extension (P = 0.0562). Furthermore, the RFS rate of patients with massive posterior extension only to the recurrent nerve demonstrated a better RFS rate than those with extension to other posterior organs (P = 0.0052). Multivariate analysis demonstrated that massive extrathyroid extension is recognized as an independent prognostic factor for RFS (P = 0.0003).ConclusionsThese findings suggest that (1) upgrading of T category for tumors with massive extension is appropriate, whereas that for tumors with only minimal extension is not, and (2) careful surgical treatment and postoperative follow‐up are required for tumors with massive extension to posterior organs other than the recurrent laryngeal nerve.
Seasonal marine feeding and body condition of sea trout (Salmo trutta) at its northern distribution
Authors: Rikardsen A.H. , Amundsen P-A. , Knudsen R. , Sandring S. 
Published: January 2006

AbstractThe seasonal marine feeding pattern of sea trout was studied from March to December 2001 in two large fjords situated at latitudes 69°N and 66°N in the northern part of Norway. Despite low sea temperatures and high salinity, sea running trout were caught during all sampling occasions in both fjords. The trout had fed extensively on marine crustaceans (shrimps, amphipods, and krill) and polychaetes during early and late winter, and had a stable or increasing condition factor during this period. In summer and autumn, the trout fed predominantly on fish, mainly juvenile herring. Food consumption rates were lowest during late autumn and early winter (October–December) in both fjords, while trout in the southernmost fjord had the highest consumption rates from April to August and trout in the northernmost fjord from May to September. These patterns in both fjords matched the seasonal variations in condition factor and relative lipid content of the fish during the same periods. The marine winter migration of these northern sea trout populations appears to be a feeding migration in which the fish maintain or increase their body condition, representing a previously undocumented alternative to the more common life history strategy of over-wintering and starvation in freshwater at the northern distribution of this species.