bluuebunny/crossref_metadata_2025 huggingface dataset:
The unsteady three-dimensional wake produced by a trapezoidal pitching panel
Authors: Green Melissa A. , Rowley Clarence W. , Smits Alexander J.
Published: September 2011

Particle image velocimetry (PIV) is used to investigate the three-dimensional wakes of rigid pitching panels with a trapezoidal geometry, chosen to model idealized fish caudal fins. Experiments are performed for Strouhal numbers from 0.17 to 0.56 for two different trailing edge pitching amplitudes. A Lagrangian coherent structure (LCS) analysis is employed to investigate the formation and evolution of the panel wake. A classic reverse von Kármán vortex street pattern is observed along the mid-span of the near wake, but the vortices realign and exhibit strong interactions near the spanwise edges of the wake. At higher Strouhal numbers, the complexity of the wake increases downstream of the trailing edge as the spanwise vortices spread transversely and lose coherence as the wake splits. This wake transition is shown to correspond to a qualitative change in the LCS pattern surrounding each vortex core, and can be identified as a quantitative event that is not dependent on arbitrary threshold levels. The location of this transition is observed to depend on both the pitching amplitude and free stream velocity, but is not constant for a fixed Strouhal number. On the panel surface, the trapezoidal planform geometry is observed to create additional vortices along the swept edges that retain coherence for low Strouhal numbers or high sweep angles. These additional swept-edge structures are conjectured to add to the complex three-dimensional flow near the tips of the panel.
Milk yield and somatic cell count during the following lactation after selective treatment of cows at dry-off
Authors: Rajala-Schultz Päivi J , Torres Audrey H , DeGraves Fred J
Published: September 2011

Selective dry cow therapy (SDCT) has received increasing attention in recent years owing to global concerns over agricultural use of antimicrobial drugs and development of antimicrobial resistance. The objective of this study was to evaluate the effect of SDCT on milk yield and somatic cell count (SCC) in dairy herds in the USA. Cows in four Ohio dairy herds were categorized into two groups (low-SCC and high-SCC) at dry-off based on their SCC and clinical mastitis (CM) history during the lactation preceding the dry-off. Low-SCC cows were randomly assigned to receive or not to receive intramammary antibiotics at dry-off. Milk yield and SCC of these cows during the following lactation were compared using linear mixed effects models, adjusting for parity, calving season, stage of lactation, previous lactation milk yield and herd. Milk yield of untreated and treated low-SCC cows at dry-off did not differ significantly during the following lactation. Overall, treated low-SCC cows had 16% lower SCC (approximately 35 000 cells/ml,P=0·0267) than the untreated cows during the following lactation; however, the effect was variable in different herds. Moreover the impact of treatment, or the lack thereof, on milk yield varied considerably between herds. The results suggested that in some herds treating all cows at dry-off may be beneficial while in other herds leaving healthy cows without antibiotic dry cow treatment has no negative impact on milk yield or milk quality (SCC), and in fact, may be beneficial. Further studies are needed to identify characteristics of herds where treating all cows routinely at dry-off may be needed for maintaining good udder health and where switching to selective treatment of cows at dry-off would be the optimal approach to achieve best results.
A new species of Zanclea (Cnidaria: Hydrozoa) associated with scleractinian corals from Okinawa, Japan
Authors: Hirose M. , Hirose E.
Published: September 2011

The new species of Zanclea sango sp. nov. is described from Okinawajima Island, Ryukyu Archipelago, south-western Japan. The new hydrozoan species is associated with at least three scleractinian corals (Pavona divaricata, P. venosa and Psammocora contigua). Zanclea sango sp. nov. is a polymorphic hydroid and the hydrorhiza grows between the coral skeleton and calicoblastic ectoderm. The hydrocaulus and hydrorhiza are surrounded by perisarc. Newly released medusae are almost spherical, with four perradial exumbrellar nematocyst pouches including stenoteles, and two long marginal tentacles with cnidophores containing macrobasic euryteles. Zanclea sango sp. nov. is allied to Zanclea gilii Boero et al., 2000 and Zanclea margaritae Pantos & Bythell, 2010, but it is distinguished by its cnidome, the presence of a perisarc around hydrorhiza, and lower host-specificity. According to a hypothetical Zanclea phylogeny, the ancestral species of Zanclea had an opportunistic association with some benthic organisms, such as algae or bivalves, and its hydrorhiza was covered by a perisarc. Later, some species established specific associations with benthic animals, after which the hydrorhiza lost the perisarc and became directly covered with host tissue. Among Zanclea inhabiting corals, the present species, with multiple coral host species and a perisarc around the hydrorhiza, seems to retain more ancestral character states than Z. gilii and Z. margaritae, which have specific coral host species and no perisarc around the hydrorhiza.
Do interrelationships among benthic components mirror disturbance levels?
Authors: Malea P. , Kevrekidis T. , Papageorgiou N. , Mogias A. , Arvanitidis C.
Published: September 2011

The hypothesis tested in this study is that changes in benthic ecosystem components interrelationships may mirror the degree of environmental stress in the Mediterranean coastal lagoons. Multivariate matrices deriving from four benthic components (macrophytes, zoobenthos, epibenthic decapods and demersal fish) from four lagoonal stations along a well-defined disturbance gradient were compared by means of second-stage non-metric multidimensional scaling (MDS). The resulting inter-matrix distances were used as a proxy for the identification of the degree of disturbance. The approach followed is novel in that it uses information from higher levels of the biological organization by taking into account more than a single benthic component, thus representing broad categories of functional groups. The second-stage MDS plots depict differences between inter-component distances in the sampling stations according to the degree of disturbance they experience and the BIOENV analysis demonstrates that certain components are correlated with the environmental variables at a higher degree in the most disturbed stations.
Preparing dossiers: strength of the evidence and problems of proof
Authors: Richardson David P.
Published: September 2011

In Europe, for authorisation of a health claim, applicants must follow the procedures in the legislation and in the guidelines for submission of a dossier set out by the European Food Safety Authority. The Functional Foods in Europe (FUFOSE) and Process for the Assessment of Scientific Support for Claims on Foods (PASSCLAIM) projects underpinned the laws and provided criteria against which the quality of the totality of the available data could be judged. Whereas the regulations and PASSCLAIM require an assessment of the extent to which cause and effect can be demonstrated between a food category, a food or constituent and a health benefit, the European Food Safety Authority requires conclusive evidence of cause and effect. This latter standard of proof and a focus on randomised controlled trials done on isolated components and using validated physiological biomarkers may not always be appropriate to assess nutrition science. The aims of this paper are to address the strengths and weaknesses of different sources of evidence that contribute to the totality of the available data, to undertake a critical examination of the application of a drug-like assessment model in evidence-based nutrition and to encourage research on new biomarkers of health and homeostatic adaptability. There is a need for (a) a robust and pragmatic scientific framework for assessing the strength, consistency and biological plausibility of the evidence, and (b) consumer understanding research on claims that use qualifying language and/or graphics to reflect the weight of evidence. Such scientific, policy and communication approaches are proportionate and could help stimulate academic research, promote fair trade and product innovation and contribute to consumer education about food and health.
Twisted Paths to European Integration: Comparing Agriculture and Transport Policies in a Transnational Perspective
Authors: PATEL KIRAN KLAUS , SCHOT JOHAN
Published: September 2011

Taking the comparison of agricultural and transport policies as an example, this article argues for a new way of writing European integration history. It goes beyond the state-centric confines of the diplomatic history which has dominated the field so far and challenges the teleologies in most accounts. Instead, it argues for the need to take into account long-term perspectives as well as the role of transnational actors with a more contingent narrative. Moreover, it demonstrates that the availability of alternative inter- and transnational regimes can be decisive for the trajectory of integration within EC/EU parameters.
Addicted to Exercise
Authors: Parastatidou Irini S. , Doganis Georgios , Theodorakis Yannis , Vlachopoulos Symeon P.
Published: September 2011

The study examines the factor structure, internal consistency, concurrent and discriminant validity, and test-retest reliability of the Exercise Dependence Scale-Revised scores (EDS-R: Symons-Downs, Hausenblas, & Niggs, 2004 ) in a sample of Greek exercise participants. The Greek translation of the EDS-R was completed by 581 exercise participants along with measures of exercise addiction. Confirmatory factor analysis provided support for the hypothesized EDS-R correlated 7-factor model along with evidence for strong item loadings and factor discriminant validity. Further evidence emerged in favor of the internal consistency, concurrent validity, and test-retest reliability of the translated EDS-R scores. The results provide initial support for various aspects of the validity and reliability of the translated-into-Greek EDS-R scores.
A Turkish Adaptation of the Coping Scales From the German Stress and Coping Questionnaire for Children and Adolescents
Authors: Eschenbeck Heike , Heim-Dreger Uwe , Tasdaban Elif , Lohaus Arnold , Kohlmann Carl-Walter
Published: September 2011

The present study develops and validates a Turkish adaptation of the coping scales from the German Stress and Coping Questionnaire for Children and Adolescents (SSKJ 3–8; Lohaus, Eschenbeck, Kohlmann, & Klein-Heßling, 2006 ). In a Turkish sample of 473 children and adolescents from grades 4 to 8 (220 girls, 253 boys, age range: 9–15 years), the factor structure of the original German version was confirmed for the six subscales: seeking social support, problem solving, avoidant coping, palliative emotion regulation, anger-related emotion regulation, and media use. All six subscales showed good internal consistency. Correlations between these subscales and indicators of psychological adjustment as well as replication of gender differences for the subscales also demonstrated high correspondence between the original German version of the SSKJ 3–8 coping scales and the Turkish adaptation.
Character Strengths in Israel
Authors: Littman-Ovadia Hadassah , Lavy Shiri
Published: September 2011

The Values in Action Inventory of Strengths (VIA-IS) has been extensively used to assess character strengths. We adapted a Hebrew translation and analyzed its psychometric properties and associations with life satisfaction, personality traits, and positive and negative affect, and examined its factorial structure in 635 Israeli adults. Results indicated the following: (1) All 24 subscales had satisfactory reliabilities (αs > .72). (2) Hope, gratitude, vitality, curiosity, and love had the highest associations with life satisfaction, whereas modesty, appreciation of beauty, fairness, humor and honesty, had the lowest. (3) Women scored higher than men on love, appreciation of beauty and gratitude, with men scoring higher on creativity. (4) A five-dimensional model best represented the factorial structure. Most findings replicated previous findings in other countries, supporting the use of the Hebrew version.
Eating Disorder Examination Questionnaire (EDE-Q)
Authors: Penelo Eva , Villarroel Ana M. , Portell Mariona , Raich Rosa M.
Published: September 2011

Background: Most studies on the Eating Disorder Examination Questionnaire (EDE-Q) focus exclusively on women. Aims: To examine the internal consistency and convergent validity of the EDE-Q in Spanish undergraduate men and to compare the results with those obtained previously in college samples of Spanish women and American men. Methods: 269 college men, aged 18–30 years, answered the EDE-Q, Eating Disorder Inventory (EDI-2), and Body Shape Questionnaire (BSQ). Results: The four subscale scores and the global score of the EDE-Q achieved acceptable internal consistency (α ≥ .65), and evidence on convergent validity with EDI-2 and BSQ was obtained (r ≥ .41). Average scores, standard deviations, and percentile ranks for the raw EDE-Q subscales and data on the occurrence of binge eating and compensatory behaviors are presented. Most values were lower than those found in previous studies with Spanish undergraduate women and American undergraduate men. Discussion: Lower scores in EDE-Q subscales provide country differences between Spain and United States and support the existence of gender differences in eating disorders attitudes. These data should help clinicians and researchers to interpret the EDE-Q scores of college men in Spain.
Atmospheric CO2 decline during the Pliocene intensification of Northern Hemisphere glaciations
Authors: Bartoli Gretta , Hönisch Bärbel , Zeebe Richard E.
Published: September 2011

Several hypotheses have been put forward to explain the onset of intensive glaciations on Greenland, Scandinavia, and North America during the Pliocene epoch between 3.6 and 2.7 million years ago (Ma). A decrease in atmospheric CO2 may have played a role during the onset of glaciations, but other tectonic and oceanic events occurring at the same time may have played a part as well. Here we present detailed atmospheric CO2 estimates from boron isotopes in planktic foraminifer shells spanning 4.6–2.0 Ma. Maximal Pliocene atmospheric CO2 estimates gradually declined from values around 410 μatm to early Pleistocene values of 300 μatm at 2.0 Ma. After the onset of large‐scale ice sheets in the Northern Hemisphere, maximal pCO2 estimates were still at 2.5 Ma +90 μatm higher than values characteristic of the early Pleistocene interglacials. By contrast, Pliocene minimal atmospheric CO2 gradually decreased from 310 to 245 μatm at 3.2 Ma, coinciding with the start of transient glaciations on Greenland. Values characteristic of early Pleistocene glacial atmospheric CO2 of 200 μatm were abruptly reached after 2.7 Ma during the late Pliocene transition. This trend is consistent with the suggestion that ocean stratification and iron fertilization increased after 2.7 Ma in the North Pacific and Southern Ocean and may have led to increased glacial CO2 storage in the oceanic abyss after 2.7 Ma onward.
Modulation of STIM1 and capacitative Ca2+ entry by the endoplasmic reticulum luminal oxidoreductase ERp57
Authors: Prins Daniel , Groenendyk Jody , Touret Nicolas , Michalak Marek
Published: September 2011

STIM1 is an endoplasmic reticulum (ER) membrane Ca2+ sensor responsible for activation of store‐operated Ca2+ influx. We discovered that STIM1 oligomerization and store‐operated Ca2+ entry (SOC) are modulated by the ER oxidoreductase ERp57. ERp57 interacts with the ER luminal domain of STIM1, with this interaction involving two conserved cysteine residues, C49 and C56. SOC is accelerated in the absence of ERp57 and inhibited in C49 and C56 mutants of STIM1. We show that ERp57, by ER luminal interaction with STIM1, has a modulatory role in capacitative Ca2+ entry. This is the first demonstration of a protein involved in ER intraluminal regulation of STIM1.
miRNA screening reveals a new miRNA family stimulating iPS cell generation via regulation of Meox2
Authors: Pfaff Nils , Fiedler Jan , Holzmann Angelika , Schambach Axel , Moritz Thomas , Cantz Tobias , Thum Thomas
Published: September 2011

Induced pluripotent stem cells (iPSCs) can be generated by overexpression of Oct4, Sox2 and Klf4 in murine fibroblasts. By conducting a microRNA (miRNA) library screen, we identified a set of miRNAs critically regulating iPSC formation. We revealed a new miRNA family (miR‐130/301/721) as an important regulator of iPSC induction by targeting the homeobox transcription factor Meox2 (also known as Gax). Meox2‐specific silencing mimicked the effects of this miRNA family on reprogramming. Mechanistically, miRNA‐resistant Meox2 overexpression abrogated effects of miR‐130/301/721 on reprogramming. In conclusion, the miRNA family miR‐130/301/721 enhances iPSC generation via repression of Meox2.
Identification of novel small molecules that elevate Klotho expression
Authors: King Gwendalyn D. , Chen CiDi , Huang Mickey M. , Zeldich Ella , Brazee Patricia L. , Schuman Eli R. , Robin Maxime , Cuny Gregory D. , Glicksman Marcie A. , Abraham Carmela R.
Published: September 2011

The absence of Klotho (KL) from mice causes the development of disorders associated with human aging and decreased longevity, whereas increased expression prolongs lifespan. With age, KL protein levels decrease, and keeping levels consistent may promote healthier aging and be disease-modifying. Using the KL promoter to drive expression of luciferase, we conducted a high-throughput screen to identify compounds that activate KL transcription. Hits were identified as compounds that elevated luciferase expression at least 30%. Following validation for dose-dependent activation and lack of cytotoxicity, hit compounds were evaluated further in vitro by incubation with opossum kidney and Z310 rat choroid plexus cells, which express KL endogenously. All compounds elevated KL protein compared with control. To determine whether increased protein resulted in an in vitro functional change, we assayed FGF23 (fibroblast growth factor 23) signalling. Compounds G–I augmented ERK (extracellular-signal-regulated kinase) phosphorylation in FGFR (fibroblast growth factor receptor)-transfected cells, whereas co-transfection with KL siRNA (small interfering RNA) blocked the effect. These compounds will be useful tools to allow insight into the mechanisms of KL regulation. Further optimization will provide pharmacological tools for in vivo studies of KL.
Nedd4-dependent lysine-11-linked polyubiquitination of the tumour suppressor Beclin 1
Authors: Platta Harald W. , Abrahamsen Hilde , Thoresen Sigrid B. , Stenmark Harald
Published: September 2011

Beclin 1, a subunit of the class III phosphatidylinositol 3-kinase complex, is a tumour suppressor with a central role in endocytic trafficking, cytokinesis and the cross-regulation between autophagy and apoptosis. Interestingly, not only reduced expression but also overexpression of Beclin 1 is correlated with cancer development and metastasis. Thus it seems necessary for the cell to balance the protein levels of Beclin 1. In the present study we describe a regulatory link between Beclin 1 and the ubiquitin ligase Nedd4 (neural-precursor-cell-expressed developmentally down-regulated 4). We establish Nedd4 as a novel binding partner of Beclin 1 and demonstrate that Nedd4 polyubiquitinates Beclin 1 with Lys11- and Lys63-linked chains. Importantly, Nedd4 expression controls the stability of Beclin 1, and depletion of the Beclin 1-interacting protein VPS34 causes Nedd4-mediated proteasomal degradation of Beclin 1 via Lys11-linked polyubiquitin chains. Beclin 1 is thus the first tumour suppressor reported to be controlled by Lys11-linked polyubiquitination.
Lifetime-degrading boron-oxygen centres in p-type and n-type compensated silicon
Authors: Voronkov V. V. , Falster R. , Bothe K. , Lim B. , Schmidt J.
Published: September 2011

Degradation of minority carrier lifetime under illumination occurs in boron-containing Czochralski silicon of both p- and n-type. In n-Si, the recombination centre responsible for degradation is found to be identical to the fast-stage centre (FRC) known for p-Si, where it is produced at a rate proportional to the squared hole concentration, p2. Holes in n-Si are the excess minority carriers—of a relatively low concentration; hence, the time scale of FRC generation is increased by several orders of magnitude when compared to p-Si. The degradation kinetics, which is non-linear, due to dependence of p on the current concentration of FRC, is well reproduced by simulations. The injection level dependence of the lifetime shows that FRC exists in 3 charge states (− 1, 0, + 1) possessing 2 energy levels. Comparison of n-Si samples of various electron concentrations shows that FRC emerges by the reconstruction of a latent BsO2 complex of a substitutional boron and an oxygen dimer (while the major recombination centre in p-Si denoted SRC was previously found to emerge by reconstruction of BiO2 defect involving an interstitial boron atom). A model of the BsO2 reconfiguration into FRC through an intermediate state accounts for the rate constant dependence on p, which is reduced to a p2 proportionality, under certain conditions.
A microfluidic chip for highly efficient cell capturing and pairing
Authors: Cui Shaoyan , Liu Yaoping , Wang Wei , Sun Yan , Fan Yubo
Published: September 2011

This paper examined the feasibility of a microfluidics chip for cell capturing and pairing with a high efficiency. The chip was fabricated by the polydimethylsiloxane-based soft-lithography technique and contained two suction duct arrays set in parallel on both sides of a main microchannel. Cells were captured and paired by activating two sets of suction ducts one by one with the help of syringe pumps along with switching the cell suspensions inside the main microchannel correspondingly. The effects of suction flow rate and the dimensions of suction channels on the cell capturing and pairing efficiency were characterized. The present chip was capable of creating 1024 pairs of two different cell populations in parallel. The preliminary experimental results showed that the cell capturing efficiency was 100% and the pairing one was 88% with an optimal suction rate of 5 μl/min in the chip in the 2 μm-sized suction duct chip. The cell viability after capture inside the microfluidic device was 90.0 ± 5.3%. With this cell capturing and pairing chip, interaction between cells in a single pair mode can be studied. The ability to create cell pairs has a number of biological applications for cell fusion, cell-cell interaction studies, and cell toxicity screening.
Electromagnetic response and homogenization of grids of ferromagnetic microwires
Authors: Liberal I. , Nefedov I. S. , Ederra I. , Gonzalo R. , Tretyakov S. A.
Published: September 2011

This contribution presents an analytical formulation for the electromagnetic response of grids of ferromagnetic microwires, where the electromagnetic fields produced by the structure are found by means of the local field method. In addition, a circuit analogy is introduced for a better understanding of the grid response, where a single ferromagnetic microwire is modeled as an impedance-loaded wire, and the transmission-line approach is used for the whole grid. Moreover, the homogenization of the structure is considered to provide more physical insight into internal polarizations of the grid. Contrary to the previous experiments of left-handed transmission in grids of ferromagnetic microwires, it is found that such structures can be modeled as artificial dielectric slabs with a frequency dispersive permittivity.
Note: Anti-strong-disturbance signal processing method of vortex flowmeter with two sensors
Authors: Xu Ke-Jun , Luo Qing-Lin , Fang Ming , Wang Gang , Liu San-Shan , Kang Yi-Bo , Shi Lei
Published: September 2011

Some digital signal processing methods have been used to deal with the output signal of vortex flowmeter for extracting the flow rate frequency from the noisy output of vortex flow rate sensor and achieving the measurement of small flow rate. In applications, however, the power of noise is larger than that of flow rate sometimes. These strong disturbances are caused by pipe vibration mostly. Under this condition the previous digital signal processing methods will be unavailable. Therefore, an anti-strong-disturbance solution is studied for the vortex flowmeter with two sensors in this Note. In this solution, two piezoelectric sensors are installed in the vortex probe. One is called the flow rate sensor for measuring both the flow rate and vibration noise, and the other is called the vibration sensor for detecting the vibration noise and sensing the flow rate signal weakly at the same time. An anti-strong-disturbance signal processing method combining the frequency-domain substation algorithm with the frequency-variance calculation algorithm is proposed to identify the flow rate frequency. When the peak number of amplitude spectrum of the flow rate sensor is different from that of the vibration sensor, the frequency-domain subtraction algorithm will be adopted; when the peak number of amplitude spectrum of the flow rate sensor is the same as that of the vibration sensor, the frequency-variance calculation algorithm will be employed. The whole algorithm is implemented in real time by an ultralow power micro control unit (MCU) to meet requirements of process instrumentation. The experimental results show that this method can obtain the flow rate frequency correctly even if the power of the pipe vibration noise is larger than that of the vortex flow rate signal.
Mayer-sampling Monte Carlo calculations of uniquely flexible contributions to virial coefficients
Authors: Shaul Katherine R. S. , Schultz Andrew J. , Kofke David A.
Published: September 2011

We present methods for computing contributions to the virial coefficients uniquely associated with molecular flexibility, and we demonstrate their use with application to the third, fourth, and fifth virial coefficients of united-atom models of linear alkanes and methanol belonging to the suite of transferrable potentials for phase equilibria (TraPPE-UA). We find that these uniquely flexible contributions are more difficult to compute than the remainder of the coefficient, especially for the conditions at which they appear to be most important. The significance of these contributions relative to the full virial coefficient grows with the number of sites (the size of the molecule), the number of molecules, and, to a certain extent, the temperature. The nature of the site-site interactions is of great importance: the significance of the uniquely flexible contribution at third and fourth order is orders of magnitude larger for TraPPE-UA methanol, which has Coulombic interactions, than for TraPPE-UA propane, which does not, even though both models have three sites per molecule and comparable bending potentials. While the uniquely flexible contribution of TraPPE-UA propane has a negligible impact on its third-order virial-equation-of-state estimate of the critical point, the uniquely flexible contribution of TraPPE-UA methanol increases this estimate of its critical pressure by about 5%.
First principles study of the structural, electronic, and dielectric properties of amorphous HfO2
Authors: Chen Tsung-Ju , Kuo Chin-Lung
Published: September 2011

Using first-principles density-functional theory calculations, we have investigated the structural, electronic, and dielectric properties, as well as the O vacancy formation in amorphous HfO2. The structural properties of the generated amorphous models were analyzed via the pair correlation functions and the distribution of the atomic coordination number. The PBE0 hybrid density functional was employed for the analysis of the electronic properties and the charge transition levels of the O vacancy in amorphous HfO2. The dielectric and vibrational properties of the generated models were analyzed using the linear response method based on the density functional perturbation theory. According to the generated structural models, the density of a-HfO2 was 8.63 g/cm3, and the average coordination numbers of O and Hf atom were 3.06 and 6.10, respectively. The electronic band gap of a-HfO2 was predicted to be 5.94 eV, and the static dielectric constants were calculated to be ∼ 22, both in good agreements with the experimental measurements. The computed formation energy of a neutral O vacancy in a-HfO2 was 6.50 eV on average, which is lower than that in m-HfO2 by 0.2–0.3 eV but remains higher than that in a-SiO2. Unlike in m-HfO2, the highest occupied defect levels of the negatively charged O vacancies in a-HfO2 may lie within the band-gap region of silicon. In addition, O vacancies in the charge state q =− 2 may appear as a stable state as the electron chemical potential lies within the electronic band gap, and thus, some of the O vacancies can possess the negative-U property in a-HfO2.
Hierarchical expansion of the kinetic energy operator in curvilinear coordinates for the vibrational self-consistent field method
Authors: Strobusch D. , Scheurer Ch.
Published: September 2011

A new hierarchical expansion of the kinetic energy operator in curvilinear coordinates is presented and modified vibrational self-consistent field (VSCF) equations are derived including all kinematic effects within the mean field approximation. The new concept for the kinetic energy operator is based on many-body expansions for all \documentclass[12pt]{minimal}\begin{document}$\cal G$\end{document}G matrix elements and its determinant. As a test application VSCF computations were performed on the H2O2 molecule using an analytic potential (PCPSDE) and different hierarchical approximations for the kinetic energy operator. The results indicate that coordinate-dependent reduced masses account for the largest part of the kinetic energy. Neither kinematic couplings nor derivatives of the \documentclass[12pt]{minimal}\begin{document}$\cal G$\end{document}G matrix nor its determinant had significant effects on the VSCF energies. Only the zero-point value of the pseudopotential yields an offset to absolute energies which, however, is irrelevant for spectroscopic problems.
On holographic realization of logarithmic Galilean conformal algebra
Authors: Hosseiny Ali , Naseh Ali
Published: September 2011

We study two-dimensional logarithmic Galilean conformal algebra (LGCA) by making use of a contraction of topologically massive gravity at critical point. We observe that using a naive contraction at the critical point fails to give a well defined theory, though contracting the theory while we are approaching the critical point leads to a well behaved expression for two point functions of the energy-momentum tensors of LGCA.
Pulsed discharge jet electronic spectroscopy of the aluminum dicarbide (AlC2) free radical
Authors: Yang Jie , Judge Richard H. , Clouthier Dennis J.
Published: September 2011

Laser-induced fluorescence and wavelength resolved emission spectra of the $\tilde C$C̃ 2B2–$\tilde X$X̃ 2A1 band system of the gas phase aluminum dicarbide free radical have been obtained using the pulsed discharge jet technique. The radical was produced by electron bombardment of a precursor mixture of trimethylaluminum in high-pressure argon. The three vibrational frequencies of T-shaped AlC2 have been determined in both the combining states along with several of the anharmonicity constants. The $0_0^0$000 band has been recorded with high resolution and rotationally analyzed. The spectrum is complicated by partially resolved spin-rotation and aluminum hyperfine splittings. Where necessary, we have fixed the spin-rotation constants used in the rotational analysis at the values predicted by density functional theory. The derived molecular structures are: $r^{\prime \prime} _0$r0′′(C–C) = 1.271(2) Å, $r^{\prime \prime} _0$r0′′(Al–C) = 1.926(1) Å, θ″(C–Al–C) = 38.5(2)°, $r^{\prime} _0$r0′(C–C) = 1.323(2) Å, $r^{\prime} _0$r0′(Al–C) = 1.934(1) Å, and θ′(C–Al–C) = 40.0(2)°. Unlike SiC2, aluminum dicarbide shows no spectroscopic evidence of facile isomerization to the linear structure in the ground electronic state.
Breaking internal wave groups: Mixing and momentum fluxes
Authors: Birch Daniel A. , Sundermeyer Miles A.
Published: September 2011

Breaking groups of large-amplitude internal gravity waves are simulated numerically and the resulting diapycnal mixing and residual momentum are quantified. The wave frequency strongly affects the mixing, with high- and low-frequency waves doing many times more mixing than intermediate-frequency waves with the same steepness. The total residual momentum remaining in the breaking region after the remnants of the wave group propagates away shows similar frequency dependence as the diapycnal mixing. Additionally, the propagation of the breaking events and the spatial distribution of the mixing are found to agree qualitatively with a kinematic description of breaking internal wave groups.
Aggregation of polymer-grafted nanoparticles in good solvents: A hierarchical modeling method
Authors: Cheng Lisheng , Cao Dapeng
Published: September 2011

Brownian dynamics simulations are carried out to study the aggregation behavior of polymer-grafted nanoparticles (NPs) in good solvents by using the coarse-grained model derived from the all-atom force field, according to the hierarchical modeling strategy, and here PEG-grafted gold nanoparticles (GNPs) were taken as an example. Generally, grafting PEG to the surface of GNPs is to protect them from aggregation in the solution. However, our results reveal that PEG-grafted GNPs may also aggregate when concentration increases. Our simulations indicate that there exists a critical aggregating concentration (CAC), beyond which the PEG-grafted GNPs will aggregate. We further check the effects of grafting density and the length of grafted chains on the aggregation behavior of the grafted GNPs, and find that there exists an optimized length of grafted chain, at which the system has the maximal CAC. Furthermore, the aggregate size of self-assembled mesostructures formed by the grafted GNPs increases with the concentration. Interestingly, it is observed that the aggregation favors to form linear gold nanowires rather than compact gold nanoclusters, and the corresponding mechanism is also addressed. It is expected that this work would provide useful information for the fabrication of metal nanowires and the surface modification of metal nanoparticles.
Average relaxation time of internal spectrum for carbosilane dendrimers: Nuclear magnetic resonance studies
Authors: Markelov Denis A. , Matveev Vladimir V. , Ingman Petri , Lähderanta Erkki , Boiko Natalia I.
Published: September 2011

A new theoretical description of the interior mobility of carbosilane dendrimers has been tested. Experiments were conducted using measurements of the 1H NMR spin-lattice relaxation time, T1H, of two-, three- and four-generation carbosilane dendrimers with three different types of terminal groups in dilute chloroform solutions. Temperature dependences of the NMR relaxation rate, 1/T1H, were obtained for the internal CH2 – groups of the dendrimers in the range of 1/T1H maximum, allowing us to directly evaluate the average time of the internal spectrum for each dendrimer. It was found that the temperature of 1/T1H maximum is practically independent of the number of generations, G; therefore, the theoretical prediction was confirmed experimentally. In addition, the average time of the internal spectrum of carbosilane dendrimers was found to be near 0.2 ns at room temperature, and this value correlates well with the values previously obtained for other dendrimer structures using other experimental techniques.
CO2 adsorption on TiO2(101) anatase: A dispersion-corrected density functional theory study
Authors: Sorescu Dan C. , Al-Saidi Wissam A. , Jordan Kenneth D.
Published: September 2011

Adsorption, diffusion, and dissociation of CO2 on the anatase (101) surface were investigated using dispersion-corrected density functional theory. On the oxidized surface several different local minima were identified of which the most stable corresponds to a CO2 molecule adsorbed at a five-fold coordinated Ti site in a tilted configuration. Surface diffusion is characterized by relatively small activation barriers. Preferential diffusion takes place along Ti rows and involves a cartwheel type of motion. The presence of a bridging oxygen defect or a surface interstitial Ti atom allows creation of several new strong binding configurations the most stable of which have bent CO2 structures with simultaneous bonding to two surface Ti atoms. Subsurface oxygen vacancy or interstitial Ti defects are found to enhance the bonding of CO2 molecules to the surface. CO2 dissociation from these defect sites is calculated to be exothermic with barriers less than 21 kcal/mol. The use of such defects for catalytic activation of CO2 on anatase (101) surface would require a mechanism for their regeneration.
Robust inverse energy cascade and turbulence structure in three-dimensional layers of fluid
Authors: Byrne D. , Xia H. , Shats M.
Published: September 2011

Here, we report the first evidence of the inverse energy cascade in a flow dominated by 3D motions. Experiments are performed in thick fluid layers where turbulence is driven electromagnetically. It is shown that if the free surface of the layer is not perturbed, the top part of the layer behaves as quasi-2D and supports the inverse energy cascade regardless of the layer thickness. Well below the surface the cascade survives even in the presence of strong 3D eddies developing when the layer depth exceeds half the forcing scale. In a bounded flow at low bottom dissipation, the inverse energy cascade leads to the generation of a spectral condensate below the free surface. Such coherent flow can destroy 3D eddies in the bulk of the layer and enforce the flow planarity over the entire layer thickness.
Measurements of face shear properties in relaxor-PbTiO3 single crystals
Authors: Zhang Shujun , Jiang Wenhua , Meyer Richard J. , Li Fei , Luo Jun , Cao Wenwu
Published: September 2011

The face (contour) shear piezoelectric properties of Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMNT) single crystals were experimentally determined by the impedance method. Zt ± 45° cut samples with various aspect ratios were investigated based on Bechmann’s zero-order approximate solution. Square plates were found to exhibit a clean face shear vibration mode and the experimental data were in good agreement with the rotated matrix calculations and finite element method simulations. The piezoelectric coefficients d36 were determined to be in the range of 1600-2800 pC/N, depending on the compositional variations, with an ultralow frequency constant N36, in the range of 490–630 Hz.m. In contrast to conventional thickness shear modes, the mechanical quality factors of face shear vibrations are relatively high, with Q values being on the order of ∼100-450, demonstrate promising for low frequency transducer applications.
Single crystal strontium titanate surface and bulk modifications due to vacuum annealing
Authors: Hanzig Juliane , Abendroth Barbara , Hanzig Florian , Stöcker Hartmut , Strohmeyer Ralph , Meyer Dirk C. , Lindner Susi , Grobosch Mandy , Knupfer Martin , Himcinschi Cameliu , Mühle Uwe , Munnik Frans
Published: September 2011

Vacuum annealing is a widely used method to increase the electric conductivity of SrTiO3 single crystals. The induced oxygen vacancies act as intrinsic donors and lead to n-type conductivity. Apart from the changed electronic structure, however, also crystal structure modifications arise from this treatment. Hence, electronic properties are determined by the interplay between point defects and line defects. The present paper provides a survey of the real structure of commercially available SrTiO3 single crystals and the changes induced by reducing vacuum heat-treatment. Therefore, all investigations were performed ex situ, i.e., after the annealing process. Used characterization methods include atomic force microscopy, transmission electron microscopy, spectroscopic ellipsometry, infrared spectroscopy, and photoluminescence spectroscopy. Besides the expected variation of bulk properties, especially surface modifications have been detected. The intrinsic number of near-surface dislocations in the samples was reduced by vacuum annealing. X-ray photoelectron spectroscopy proves the existence of a layer of adsorbed molecules, which influences the SrTiO3 work function. Also, the interaction between adsorbates and surface point defects as well as laser annealing due to local oxygen absorption are discussed.
A spectroscopic ellispometric study of the tunability of the optical constants and thickness of GeOx films with swift heavy ions
Authors: Vijayarangamuthu K. , Singh Chaman , Kabiraj D. , Rath Shyama
Published: September 2011

Sub-stoichiometric GeOx films were fabricated by electron-beam evaporation method. The films were irradiated with 100 MeV Ag7+ ions at fluences between 1 × 1012 and 1 × 1014 ions-cm−2. Spectroscopic ellipsometric measurements were performed in air at room temperature. The values of the layer thickness and refractive index were extracted from ellipsometry using a multilayer analysis and the Tauc Lorentz model. The refractive index (at 633 nm) of the as-deposited GeOx film was estimated to be 1.860 and decreased to 1.823 for films irradiated at an ion fluence of 1 × 1014 ions-cm−2. The thickness of the films also decreased after irradiation and is due to a sputtering induced by the ion beam. The change in the refractive index with ion fluence is attributed to a stoichiometric change and structural transformation represented by GeOx→ Ge + GeOy (y > x) occurring due to a thermal spike induced by ion irradiation. Swift heavy ions thus provide a scope for modulating the refractive index of GeOx films. The thickness and stoichiometric changes are supported by Rutherford backscattering measurements.
Fluctuation-induced tunneling conduction through RuO2 nanowire contacts
Authors: Lin Yong-Han , Lin Juhn-Jong
Published: September 2011

A good understanding of the electronic conduction processes through nanocontacts is a crucial step for the implementation of functional nanoelectronic devices. We have studied the current- voltage (I-V) characteristics of nanocontacts between single metallic RuO2 nanowires and contacting Au electrodes, which were pre-patterned by simple photolithography. Both the temperature behavior of contact resistance in the low-bias voltage ohmic regime and the I-V curves in the high-bias voltage non-ohmic regime have been investigated. We found that the electronic conduction processes in the wide temperature interval 1-300 K can be well described by the fluctuation-induced tunneling (FIT) conduction theory. Taken together with our previous work [Lin et al., Nanotechnology 19, 365201 (2008)], where the nanocontacts were fabricated by delicate electron-beam lithography, our study demonstrates the general validity of the FIT model in characterizing electronic nanocontacts.
Persistent critical current of YBa2Cu3O7-δ nanowires
Authors: Mansour A. I. , Chow K. H. , Jung J.
Published: September 2011

C-axis oriented YBa2Cu3O7-δ (YBCO) nanowires have been fabricated so as to connect two c-axis oriented semi-ring-shaped YBCO thin films along the c-axis direction. This allows the characterization of high-Tc nanowires with the electrodes being of the same material. Four different lengths of the nanowire arrays were characterized. When the YBCO nanowires were narrower than 100 nm, their persistent critical current revealed an anomalous temperature dependence. The narrow YBCO nanowires behave like superconductor/semiconductor/superconductor junctions with a universal critical current density Jc(T)∝(Tc-T)3/2 at low temperatures. Above a certain temperature T*, the flow of the supercurrent is controlled by thermally activated phase-slip events, with Jc(T) following a power-law dependence Jc∝(Tc-T)α>3/2.
Electrical characteristics and carrier transport mechanisms of write-once-read-many-times memory elements based on graphene oxide diodes
Authors: Yi Mingdong , Zhao Litao , Fan Quli , Xia Xianhai , Ai Wei , Xie Linghai , Liu Xiangmei , Shi Naien , Wang Wenjun , Wang Yanping , Huang Wei
Published: September 2011

We demonstrated write-once-read-many-times (WORM) memory devices based on graphene oxide (GO) film sandwiched between ITO and LiF/Al electrode. The devices showed irreversible electrical transition from the low conductivity (OFF) state to the high conductivity (ON) state and the ON/OFF current ratio between the conductivities of two states was over 5.7 × 104. The results of I-V data, AFM and SEM images indicated that the WORM memory characteristics of GO diodes were mainly attributed to charge trapping at GO layers and interfacial properties between GO and LiF/Al electrode.
Temperature dependent resonances in superconductor photonic crystal
Authors: Raymond Ooi C. H. , Gong Qihuang
Published: September 2011

We show that it is possible to obtain large field transmission through a periodic structure at frequencies where the field is lossy in a finite temperature superconductor. The feat is accomplished by using thin superconducting layers. This makes the superconductor photonic crystal useful for transmitting signals over larger distances at higher temperature. Narrow transmission resonances due to surface plasmon effect are damped more quickly with increasing temperature than broader transmission bands. The temperature dependence is useful, particularly for developing optothermal sensors in terahertz and far infrared regimes.
Sub-terahertz spectroscopic system using a continuous-wave broad-area laser diode and a spatial filter
Authors: Morikawa O. , Fujita M. , Takano K. , Hangyo M.
Published: September 2011

We have proposed a low-cost type spectroscopic system in the sub-THz region similar to the THz-TDS, in which we use a continuous-wave broad-area laser diode (BLD). The Fourier spectrum of the signal waveform is discrete and is very weak at frequencies between the discrete peaks when the BLD beam is used in free space. In order to make the spectrum suitable for spectroscopy, the BLD beam is used through a spatial filter (SF) and as a result, the amplitude of the continuous spectral components between the discrete lines increases considerably. This change is explained by considering the filtering effect of the beam patterns of the BLD by the SF. Further, we show that the signal and then the signal-to-noise ratio of the transmission spectra of a sample are enhanced by using the SF compared with our previous work.
Effect of plate thickness on particle deposition velocity onto a face-up flat plate situated parallel to an airflow
Authors: Lee Sang-Chul , Kim Won-Geun , Yook Se-Jin
Published: September 2011

The effect of plate thickness on particle deposition velocity onto a face-up flat plate in a parallel airflow was examined both numerically and experimentally. Plate thickness was varied as 0.05, 0.925, 2.3, and 6.35 mm, by considering flat plates of negligible thickness, 450 mm wafers, 5 in photomasks, and 6 in EUVL photomasks, respectively. Statistical Lagrangian particle tracking (SLPT) model with the use of commercial codes was employed. The SLPT model was validated by comparing the numerically obtained particle deposition velocities with either the theoretically predicted or the experimentally determined particle deposition velocities, for the flat plates of various thicknesses. Then, the effect of plate thickness on particle deposition velocity onto the face-up flat plate in a parallel airflow was investigated by employing the SLPT model. It was found that the effect of plate thickness should be taken into account, when the particle deposition velocity onto a 5 in photomask (2.3 mm thick) or a 6 in EUVL photomask (6.35 mm thick) was considered. However, it was anticipated that the effect of plate thickness was insignificant, when the particle deposition velocity onto a 450 mm wafer was taken into consideration.