bluuebunny/crossref_metadata_2025 huggingface dataset:
Too much of a good thing: The impact of product variety on operations and sales performance
Authors: Wan Xiang , Evers Philip T. , Dresner Martin E.
Published: January 2012

We examine the impact of product variety decisions on an operational measure – unit fill rate – and on sales performance. Results are estimated using weekly data over three years from 108 distribution centers of a major soft drink bottler. Our results show that fill rates are negatively associated with product variety at a diminishing rate. In addition, we examine the total effect of product variety on sales including both the direct effect and the indirect effect through operations performance. The total impact of product variety on sales initially is positive, although at a diminishing rate. However, beyond a certain level, increased product variety actually results in lower sales; that is, “too much of a good thing”. Thus, the findings provide a comprehensive understanding of the impact of product variety on operations and sales performance.
Breeding for reduced methane emissions in extensive UK sheep systems
Authors: COTTLE D. J. , CONINGTON J.
Published: January 2012

Selection index theory was used to model the effects of methane (CH4) production in the breeding objective on genetic responses in Scottish Blackface sheep in hill production systems in the UK. A range of economic values (EVs) were assumed for CH4 production calculated from possible carbon prices (£/t CO2 equivalent (CO2-e)). The implicit price of carbon required for maintenance of CH4 levels or to reduce CH4 production by 0·1 kg/head/yr in a hill flock was calculated. The predicted genetic changes in CH4 production from current selection programmes that have an implicit methane EV of zero were calculated. Correlations between production traits and CH4 production were sampled from assumed normal distributions, as these correlations are currently unknown. Methane emissions are likely to increase at a rate of c. 3 kg CO2-e/ewe/yr as a result of using current industry selection indices in hill sheep farming systems in the UK. Breeding objectives for more productive hill sheep include reducing lamb losses and rearing more, heavier lambs. By placing a cost on carbon emissions to halt the genetic increase in methane, heavy penalties will be incurred by farmers in terms of reduced productivity. This amounts to £6/ewe/yr or a 5% discounted loss of £2851 per 100 ewe flock over a 10-year selection horizon. If the correlations between production traits and CH4 are positive (as expected) then an implicit carbon price of c. £272/t CO2-e is required for no genetic increase in CH4 production if methane is not measured and c. £50/t CO2-e if methane could be measured. Achievement of government targets for the whole economy of a 20% reduction in greenhouse gases (GHGs) over a 30-year period would require carbon prices (/t CO2-e) of £1396 (indirect selection) or £296 (direct selection) for the sheep industry to achieve a 20% reduction entirely via a genetic change of c. –0·1 kg methane/head/yr. These carbon prices are placed in the context of possible government policies. A combination of genetic and non-genetic measures will probably be required for cost-effective reduction in methane production to meet government targets.
Accuracy of magnetic resonance imaging in diagnosing thyroid cartilage and thyroid gland invasion by squamous cell carcinoma in laryngectomy patients
Authors: Kinshuck A J , Goodyear P W A , Lancaster J , Roland N J , Jackson S , Hanlon R , Lewis-Jones H , Sheard J , Jones T M
Published: January 2012

Objectives:

We examined the accuracy of magnetic resonance imaging in assessing thyroid cartilage and thyroid gland invasion in patients undergoing total laryngectomy for squamous cell carcinoma, by comparing histopathology results with imaging findings.

Study design:

A retrospective study reviewed histology and magnetic resonance scan results for all total laryngectomies performed between 1998–2008 at University Hospital Aintree, Liverpool.

Methods:

Pre-operative magnetic resonance images were reviewed independently by two consultant head and neck radiologists masked to the histology; their opinions were then compared with histology findings.

Results:

Eighty-one magnetic resonance scans were reviewed. There were 22 laryngectomy patients with histologically verified thyroid cartilage invasion and one patient with thyroid gland invasion. There were 31 patients with apparent radiological thyroid cartilage invasion pre-operatively (with 17 false positives), giving sensitivity, specificity, and positive and negative predictive values of 64, 71, 45 and 84 per cent, respectively. On assessing thyroid gland invasion, there were nine false positive scans and no false negative scans, giving sensitivity, specificity, and positive and negative predictive values of 100, 89, 10 and 100 per cent, respectively.

Conclusion:

Magnetic resonance scanning over-predicts thyroid cartilage and gland invasion in patients undergoing total laryngectomy. Magnetic resonance scans have limited effectiveness in predicting thyroid cartilage invasion by squamous cell carcinoma in laryngectomy patients.
PI3K/AKT, MAPK and AMPK signalling: protein kinases in glucose homeostasis
Authors: Schultze Simon M. , Hemmings Brian A. , Niessen Markus , Tschopp Oliver
Published: January 2012

New therapeutic approaches to counter the increasing prevalence of obesity and type 2 diabetes mellitus are in high demand. Deregulation of the phosphoinositide-3-kinase (PI3K)/v-akt murine thymoma viral oncogene homologue (AKT), mitogen-activated protein kinase (MAPK) and AMP-activated protein kinase (AMPK) pathways, which are essential for glucose homeostasis, often results in obesity and diabetes. Thus, these pathways should be attractive therapeutic targets. However, with the exception of metformin, which is considered to function mainly by activating AMPK, no treatment for the metabolic syndrome based on targeting protein kinases has yet been developed. By contrast, therapies based on the inhibition of the PI3K/AKT and MAPK pathways are already successful in the treatment of diverse cancer types and inflammatory diseases. This contradiction prompted us to review the signal transduction mechanisms of PI3K/AKT, MAPK and AMPK and their roles in glucose homeostasis, and we also discuss current clinical implications.
MODERNITY AND NATION-MAKING IN INDIA, TURKEY AND IRAN
Authors: Fernée Tadd Graham
Published: January 2012

This essay compares nation-making in India, Turkey and Iran through differing visions of modernity and Enlightenment as temporal horizons. The comparison is traced through the Islamic Triumvirate (Ottoman, Safavid and Mughal empires) focused upon the Mughal Emperor Akbar's multi-religious experiment in early modern empire consolidation. The essay then analyses the national independence movements which defined – through either violent or non-violent practice, direct seizure of state power or civil society transformation – the post-independence political formations of India, Turkey and Iran between democracy and authoritarianism. As ideal types, these experiences constitute two distinctive temporal horizons: the movement (involving the masses in nation-making as a multi-centred process) and the programme (nation-making from above employing a blueprint of rupture). The political tradition being highlighted is nation-making based upon an ethic of reconciliation over totality. This tradition links development and public freedom in creating a democratic society.
Understanding changes in water availability in the Rio Grande/Río Bravo del Norte basin under the influence of large‐scale circulation indices using the Noah land surface model
Authors: Khedun C. Prakash , Mishra Ashok K. , Bolten John D. , Beaudoing Hiroko K. , Kaiser Ronald A. , Giardino J. Richard , Singh Vijay P.
Published: January 2012

Water availability plays an important role in the socio‐economic development of a region. It is however, subject to the influence of large‐scale circulation indices, resulting in periodic excesses and deficits. An assessment of the degree of correlation between climate indices and water availability, and the quantification of changes with respect to major climate events is important for long‐term water resources planning and management, especially in transboundary basins as it can help in conflict avoidance. In this study we first establish the correlation of the Pacific Decadal Oscillation (PDO) and El Niño‐Southern Oscillation (ENSO) with gauged precipitation in the Rio Grande basin, and then quantify the changes in water availability using runoff generated from the Noah land surface model. Both spatial and temporal variations are noted, with winter and spring being most influenced by conditions in the Pacific Ocean. Negative correlation is observed at the headwaters and positive correlation across the rest of the basin. The influence of individual ENSO events, classified using four different criteria, is also examined. El Niños (La Niñas) generally cause an increase (decrease) in runoff, but the pattern is not consistent; percentage change in water availability varies across events. Further, positive PDO enhances the effect of El Niño and dampens that of La Niña, but during neutral/transitioning PDO, La Niña dominates meteorological conditions. Long El Niños have more influence on water availability than short duration high intensity events. We also note that the percentage increase during El Niños significantly offsets the drought‐causing effect of La Niñas.
The reversing roles of local and remote circulations on the Indian summer monsoon under a warming scenario
Authors: Bhaskaran B.
Published: January 2012

The simulated response of the Indian summer monsoon to increasing greenhouse gases has been fairly robust, with a majority of the climate models showing an increase in the seasonal mean rainfall and a decrease in the intensity of the associated monsoon circulation. The background global warming signal produces an increased surface and lower tropospheric meridional temperature gradient over the Indian region, while also producing anomalously positive sea surface temperatures (SSTs) in the tropical Pacific. Our analysis reveals that the monsoon outflow associated with the local circulation driven by the differential (solar plus convective) heating explains more monsoon rainfall variance than that explained by the Walker circulation driven by the remote tropical Pacific SST anomalies under a warming scenario. In the simulated present‐day climate, Walker circulation explains more rainfall variance than that explained by the local circulation, consistent with the well‐documented conventional relationships between the monsoon rainfall and ENSO. Thus, remote and local circulations reverse their corresponding roles on influencing the monsoon rainfall. Climatologically, the mean ascending branch of the Walker circulation shifts eastward, resulting in an anomalous upper level convergence and corresponding anomalous lower level divergence over the eastern tropical Indian Ocean. The resulting pressure gradients at lower levels favor the northwestward displacement of low‐level monsoon flow. At upper levels an anomalous descending motion produces an anomalous adiabatic compression over the south of the equator, reducing the upper level meridional temperature gradient. Changes in the mean local circulation reinforce the northwestward displacement of the low‐level monsoon flow and also promote upper level meridional divergent flow toward the equator.
Cerebral Microinfarcts: A Systematic Review of Neuropathological Studies
Authors: Brundel Manon , de Bresser Jeroen , van Dillen Jeroen J , Kappelle L Jaap , Biessels Geert Jan
Published: January 2012

Vascular cognitive impairment is an umbrella term for cognitive dysfunction associated with and presumed to be caused by vascular brain damage. Autopsy studies have identified microinfarcts as an important neuropathological correlate of vascular cognitive impairment that escapes detection by conventional magnetic resonance imaging (MRI). As a frame of reference for future high-resolution MRI studies, we systematically reviewed the literature on neuropathological studies on cerebral microinfarcts in the context of vascular disease, vascular risk factors, cognitive decline and dementia. We identified 32 original patient studies involving 10,515 people. The overall picture is that microinfarcts are common, particularly in patients with vascular dementia (weighted average 62%), Alzheimer's disease (43%), and demented patients with both Alzheimer-type and cerebrovascular pathology (33%) compared with nondemented older individuals (24%). In many patients, multiple microinfarcts were detected. Microinfarcts are described as minute foci with neuronal loss, gliosis, pallor, or more cystic lesions. They are found in all brain regions, possibly more so in the cerebral cortex, particularly in watershed areas. Reported sizes vary from 50 μm to a few mm, which is within the detection limit of current high-resolution MRI. Detection of these lesions in vivo would have a high potential for future pathophysiological studies in vascular cognitive impairment.
Synaptic state matching: a dynamical architecture for predictive internal representation and feature perception
Authors: Tavazoie Saeed
Published: January 2012

Here we consider the possibility that a fundamental function of sensory cortex is the generation of an internal simulation of sensory environment in real-time. A logical elaboration of this idea leads to a dynamical neural architecture that oscillates between two fundamental network states, one driven by external input, and the other by recurrent synaptic drive in the absence of sensory input. Synaptic strength is modified by a proposed synaptic state matching (SSM) process that ensures equivalence of spike statistics between the two network states. Remarkably, SSM, operating locally at individual synapses, generates accurate and stable network-level predictive internal representations, enabling pattern completion and unsupervised feature detection from noisy sensory input. SSM is a biologically plausible substrate for learning and memory because it brings together sequence learning, feature detection, synaptic homeostasis, and network oscillations under a single parsimonious computational framework.
Protein kinase D2 has a restricted but critical role in T-cell antigen receptor signalling in mature T-cells
Authors: Navarro Maria N. , Sinclair Linda V. , Feijoo-Carnero Carmen , Clarke Rosemary , Matthews Sharon A. , Cantrell Doreen A.
Published: January 2012

PKD (protein kinase D) 2 is a serine/threonine kinase activated by diacylglycerol in response to engagement of antigen receptors in lymphocytes. To explore PKD2 regulation and function in TCR (T-cell antigen receptor) signal transduction we expressed TCR complexes with fixed affinity for self antigens in the T-cells of PKD2-null mice or mice deficient in PKD2 catalytic activity. We also developed a single cell assay to quantify PKD2 activation as T-cells respond to developmental stimuli or engagement of α/β TCR complexes in vivo. Strikingly, PKD2 loss caused increases in thymic output, lymphadenopathy and splenomegaly in TCR transgenic mice. The precise magnitude and timing of PKD2 activation during T-cell development is thus critical to regulate thymic homoeostasis. PKD2-null T-cells that exit the thymus have a normal transcriptome, but show a limited and abnormal transcriptional response to antigen. Transcriptional profiling reveals the full consequences of PKD2 loss and maps in detail the selective, but critical, function for PKD2 in signalling by α/β mature TCR complexes in peripheral T-cells.
Psychische Gesundheit in der Arbeitswelt aus der Sicht von Betriebs- und Werksärzten
Authors: Dietrich Sandra , Mergl Roland , Rummel-Kluge Christine , Stengler Katarina
Published: January 2012

Anliegen Wie schätzen Betriebs-/Werksärzte Prävalenz und Umgang mit psychischen Erkrankungen ein?

Methode Befragung von Betriebs- und Werksärzten.

Ergebnisse Krankschreibungen und Erwerbsunfähigkeit aufgrund psychischer Erkrankungen nehmen zu. In 65,4 % der Unternehmen gibt es keine Präventionsprogramme. Information und Aufklärung sind wichtige Präventionsmaßnahmen.

Schlussfolgerungen Handlungsbedarf besteht bei der Aus- und Weiterbildung von Arbeitsmedizinern und der Implementierung von Präventionsmaßnahmen.
Ketamininduzierte Vesikopathie
Authors: Bader Markus , Lieb Martin , Palm Ulrich , Stief Christian , Baghai Thomas
Published: January 2012

Wir berichten über einen 25-jährigen Patienten mit jahrelangem transnasalem Ketaminmissbrauch, der sich mit starken irritativen Miktionsbeschwerden (imperativer Harndrang, Pollakis- und Dysurie) sowie stärkster Algurie vorstellte. Zystoskopisch zeigte sich das Bild einer erosiven Zystitis, die bei Fehlen konkurrierender Ätiologien als ketamininduzierte Vesikopathie verstanden werden muss. Trotz intensiver Motivation konnte der Patient nicht zu einer Ketaminabstinenz bewegt werden, sodass nach 2-maligen frustranen Heilversuchen durch Injektion von 200 I. E. sowie 400 I. E. Botulinumtoxin A in die Harnblase eine prostataerhaltende Zystektomie und Anlage einer Ileumneoblase erforderlich wurde.
Interaction of a weak discontinuity with elementary waves of Riemann problem
Authors: Radha R. , Sharma V. D.
Published: January 2012

We study the interaction of a weak discontinuity wave with the elementary waves of the Riemann problem for the one-dimensional Euler equations governing the flow of ideal polytropic gases, and investigate the effects of initial states, and the shock strength on the jumps in shock acceleration and the reflected and transmitted waves.
Electronic density of states for two-dimensional system in uniform magnetic and Aharonov–Bohm fields
Authors: Slobodeniuk A. O. , Sharapov S. G. , Loktev V. M.
Published: January 2012

We study two-dimensional electronic gas (2DEG) in the background of the Aharonov–Bohm and constant magnetic fields. The problem of ambiguity of the solutions of the Schrödinger equation is investigated by introducing a finite radius of the flux tube, which then set to zero. Wave functions and spectrum of the 2DEG Hamiltonian are used to construct an expression for the local density of states (LDOS). We obtain that LDOS has a depletion near the origin of the vortex and new peaks, which can’t be explained by using Landau levels theory.
Nonlinear effects in propagation of radio waves in metals (Review Article)
Authors: Skobov V. G. , Chernov A. S.
Published: January 2012

The main results of works on study of influence of nonlinearity on propagation of radio waves through metals placed in a constant magnetic field are described. The trapping of carriers by the magnetic field of a wave with a large amplitude leads to suppression of collisionless absorption and to a possibility of propagation in metals of waves of various types. In copper, the propagation of helicons becomes possible in the geometry when on the Fermi surface there are open orbits preventing from wave propagation. In zinc, in which the cyclotron absorption by holes exists for any wave lengths in the linear regime, the decrease of this absorption results in a possibility of propagation of an electron doppleron. In noble metals and metals of the Third Group, where any waves are absent in the linear regime, the propagation of nonlinear waves of the new type, which do not have counterparts in the linear regime, becomes possible in the range of weak fields. Multiple reflections of nonlinear waves from internal surfaces of a metallic plate lead to the formation of standing waves in a sample. In this case resonance maxima appear in a dependence of the surface resistance of the sample on a constant magnetic field. In the maxima the transparency coefficient of a metal with respect to radio emission can increase by one-two orders of magnitude.
Adsorption of small molecules on silver clusters
Authors: Wu Yu-Ning , Schmidt Martin , Leygnier Jérôme , Cheng Hai-Ping , Masson Albert , Bréchignac Catherine
Published: January 2012

We report investigations of adsorption of N2 and O2 molecules on silver cluster cations. We have first revisited structures of small silver clusters based on first-principles calculations within the framework of density functional theory with hybrid functional. The 2D to 3D transition for the neutral clusters occurs from n = 6 to 7 and for cations, in agreement with experiments, from n = 4 to 5. With the refined structures, adsorption energies of N2 and O2 molecules have been calculated. We have identified characteristic drops in the adsorption energies of N2 that further link our calculations and experiments, and confirm the reported 2D-3D transition for cations. We have found that perturbations caused by physisorbed molecules are small enough that the structures of most Ag clusters remain unchanged, even though physisorption stabilizes the 3D Ag7+ structure slightly more than the 2D counterpart. Results for pure O2 adsorption indicate that charge transfer from Agn+ to O2 occurs when n > 3. Below that size oxygen essentially physisorbes such as nitrogen to the cluster. We interpret the experimentally observed mutually cooperative co-adsorption of oxygen and nitrogen using results from density functional theory with generalized gradient approximations. The key to the enhancement is N2-induced increase in charge transfer from Agn+ cations to O2.
Debonding and fracture of ceramic islands on polymer substrates
Authors: Sun Jeong-Yun , Lu Nanshu , Yoon Juil , Oh Kyu-Hwan , Suo Zhigang , Vlassak Joost J.
Published: January 2012

We perform in-situ uniaxial tensile tests on polyimide substrates with patterned ceramic islands. The islands fail by either channel cracking or debonding from the substrate, depending on island size and thickness. To understand why different failure modes occur, we have analyzed the fracture and debonding of stiff islands on deformable substrates. Using finite element simulations, we find that the maximum tensile strain in the islands increases with island size, but decreases with island thickness. The maximum energy release rate for island/substrate debonding, in contrast, increases with both island size and thickness. Assuming that the islands do not fracture if the maximum tensile strain in the islands is lower than a critical value and that no debonding occurs if the maximum energy release rate is smaller than the interfacial toughness, the critical substrate strains for island fracture and debonding can be calculated. If the islands are thick and small, the critical debonding strain is small, and the islands fail by debonding. If the islands are large and thin, the critical fracture strain is small, and the islands fail by channel cracking. When the two critical strains are similar, debonding and cracking are expected to co-exist. Experimental observations confirm these findings.
Wavelength selective uncooled infrared sensor by plasmonics
Authors: Ogawa Shinpei , Okada Kazuya , Fukushima Naoki , Kimata Masafumi
Published: January 2012

A wavelength selective uncooled infrared (IR) sensor using two-dimensional plasmonic crystals (2D PLCs) has been developed. The numerical investigation of 2D PLCs demonstrates that the wavelength of absorption can be mainly controlled by the period of the surface structure. A microelectromechanical systems-based uncooled IR sensor with 2D PLCs as the IR absorber was fabricated through a complementary metal oxide semiconductor and a micromachining technique. The selective enhancement of responsivity was observed at the wavelength that coincided with the period of the 2D-PLC absorber.
On binding of DNA-bending proteins to DNA minicircles
Authors: Medalion Shlomi , Rabin Yitzhak
Published: January 2012

We present a theoretical study of binding of DNA-bending proteins to circular DNA, using computer simulations of the wormlike chain model of DNA. We find that the binding affinity is affected by the bending elasticity and the conformational entropy of the polymer and that while protein adsorption is identical on open and closed long DNA molecules, there is significant enhancement of binding on DNA minicircles, compared to their linear counterparts. We also find that the ratio of the radii of gyration of open and closed chains depends on protein concentration for short DNA molecules. Experimental tests of our predictions are proposed.
High-pressure optical and vibrational properties of CdGa2Se4: Order-disorder processes in adamantine compounds
Authors: Gomis O. , Vilaplana R. , Manjón F. J. , Pérez-González E. , López-Solano J. , Rodríguez-Hernández P. , Muñoz A. , Errandonea D. , Ruiz-Fuertes J. , Segura A. , Santamaría-Pérez D. , Tiginyanu I. M. , Ursaki V. V.
Published: January 2012

High-pressure optical absorption and Raman scattering measurements have been performed in defect chalcopyrite (DC) CdGa2Se4 up to 22 GPa during two pressure cycles to investigate the pressure-induced order-disorder phase transitions taking place in this ordered-vacancy compound. Our measurements reveal that on decreasing pressure from 22 GPa, the sample does not revert to the initial phase but likely to a disordered zinc blende (DZ) structure the direct bandgap and Raman-active modes of which have been measured during a second upstroke. Our measurements have been complemented with electronic structure and lattice dynamical ab initio calculations. Lattice dynamical calculations have helped us to discuss and assign the symmetries of the Raman modes of the DC phase. Additionally, our electronic band structure calculations have helped us in discussing the order-disorder effects taking place above 6–8 GPa during the first upstroke.
Amino acid analogues bind to carbon nanotube via π-π interactions: Comparison of molecular mechanical and quantum mechanical calculations
Authors: Yang Zaixing , Wang Zhigang , Tian Xingling , Xiu Peng , Zhou Ruhong
Published: January 2012

Understanding the interaction between carbon nanotubes (CNTs) and biomolecules is essential to the CNT-based nanotechnology and biotechnology. Some recent experiments have suggested that the π-π stacking interactions between protein's aromatic residues and CNTs might play a key role in their binding, which raises interest in large scale modeling of protein-CNT complexes and associated π-π interactions at atomic detail. However, there is concern on the accuracy of classical fixed-charge molecular force fields due to their classical treatments and lack of polarizability. Here, we study the binding of three aromatic residue analogues (mimicking phenylalanine, tyrosine, and tryptophan) and benzene to a single-walled CNT, and compare the molecular mechanical (MM) calculations using three popular fixed-charge force fields (OPLSAA, AMBER, and CHARMM), with quantum mechanical (QM) calculations using the density-functional tight-binding method with the inclusion of dispersion correction (DFTB-D). Two typical configurations commonly found in π-π interactions are used, one with the aromatic rings parallel to the CNT surface (flat), and the other perpendicular (edge). Our calculations reveal that compared to the QM results the MM approaches can appropriately reproduce the strength of π-π interactions for both configurations, and more importantly, the energy difference between them, indicating that the various contributions to π-π interactions have been implicitly included in the van der Waals parameters of the standard MM force fields. Meanwhile, these MM models are less accurate in predicting the exact structural binding patterns (matching surface), meaning there are still rooms to be improved. In addition, we have provided a comprehensive and reliable QM picture for the π-π interactions of aromatic molecules with CNTs in gas phase, which might be used as a benchmark for future force field developments.
Periodic orbits and non-integrability in a cosmological scalar field
Authors: Llibre Jaume , Vidal Claudio
Published: January 2012

We apply the averaging theory of first order to study the periodic orbits of Hamiltonian systems describing a universe filled with a scalar field which possesses three parameters. The main results are the following. First, we provide sufficient conditions on the parameters of these cosmological model, which guarantee that at any positive or negative Hamiltonian level, the Hamiltonian system has periodic orbits, the number of such periodic orbits and their stability change with the values of the parameters. These periodic orbits live in the whole phase space in a continuous family of periodic orbits parameterized by the Hamiltonian level. Second, under convenient assumptions we show the non-integrability of these cosmological systems in the sense of Liouville–Arnol'd, proving that there cannot exist any second first integral of class \documentclass[12pt]{minimal}\begin{document}$\mathcal {C}^1$\end{document}C1. It is important to mention that the tools (i.e., the averaging theory for studying the existence of periodic orbits and their kind of stability, and the multipliers of these periodic orbits for studying the integrability of the Hamiltonian system) used here for proving our results on the cosmological scalar field can be applied to Hamiltonian systems with an arbitrary number of degrees of freedom.
Water monomer interaction with gold nanoclusters from van der Waals density functional theory
Authors: Xue Yongqiang
Published: January 2012

We investigate the interaction between water molecules and gold nanoclusters Aun through a systematic density functional theory study within both the generalized gradient approximation and the nonlocal van der Waals (vdW) density functional theory. Both planar (n = 6–12) and three-dimensional (3D) clusters (n = 17–20) are studied. We find that applying vdW density functional theory leads to an increase in the Au–Au bond length and a decrease in the cohesive energy for all clusters studied. We classify water adsorption on nanoclusters according to the corner, edge, and surface adsorption geometries. In both corner and edge adsorptions, water molecule approaches the cluster through the O atom. For planar clusters, surface adsorption occurs in a O-up/H-down geometry with water plane oriented nearly perpendicular to the cluster. For 3D clusters, water instead favors a near-flat surface adsorption geometry with the water O atom sitting nearly atop a surface Au atom, in agreement with previous study on bulk surfaces. Including vdW interaction increases the adsorption energy for the weak surface adsorption but reduces the adsorption energy for the strong corner adsorption due to increased water-cluster bond length. By analyzing the adsorption induced charge rearrangement through Bader's charge partitioning and electron density difference and the orbital interaction through the projected density of states, we conclude that the bonding between water and gold nanocluster is determined by an interplay between electrostatic interaction and covalent interaction involving both the water lone-pair and in-plane orbitals and the gold 5d and 6s orbitals. Including vdW interaction does not change qualitatively the physical picture but does change quantitatively the adsorption structure due to the fluxionality of gold nanoclusters.
Development of roll-to-roll hot embossing system with induction heater for micro fabrication
Authors: Yun Dongwon , Son Youngsu , Kyung Jinho , Park Heechang , Park Chanhun , Lee Sunghee , Kim Byungin
Published: January 2012

In this paper, a hot embossing heating roll with induction heater inside the roll is proposed. The induction heating coil is installed inside a roll that is used as a heating roll of a roll-to-roll (R2R) hot embossing apparatus. Using an inside installed heating coil gives the roll-to-roll hot embossing system a more even temperature distribution on the surface of the heating roll compared to that of previous systems, which used an electric wire for heating. This internal induction heating roll can keep the working environment much cleaner because there is no oil leakage compared to the oiled heating roll. This paper describes the principles and provides an analysis of this proposed system; some evaluation has also been performed for the system. A real R2R hot embossing heating roll system was fabricated and some experiments on micro-pattering have been performed. After that, evaluation has been performed on the results.
Spectroscopic observation of jet-cooled 2-fluoro-m-xylyl radical
Authors: Yoon Young Wook , Lee Sang Kuk
Published: January 2012

The jet-cooled 2-fluoro-m-xylyl radical was generated and vibronically excited in a corona excited supersonic expansion from precursor 2-fluoro-m-xylene seeded in a large amount of carrier gas helium. The well-resolved visible vibronic emission spectrum of the jet-cooled 2-fluoro-m-xylyl radical was recorded using a long-path monochromator. From the analysis of the spectrum, we determine an accurate electronic energy of the D1 → D0 transition and the frequencies of vibrational modes in the ground electronic state by comparison with those of ab initio calculations and the known spectroscopic data of 2-fluoro-m-xylene for the first time.
Clustering of N impurities in ZnO
Authors: Furthmüller J. , Hachenberg F. , Schleife A. , Rogers D. , Hosseini Teherani F. , Bechstedt F.
Published: January 2012

Ab initio density functional theory and quasiparticle calculations for the incorporation of nitrogen atoms on oxygen sites in ZnO are presented. It is demonstrated that clustering of N atoms is energetically favored over the isolated N0 substitutional impurity. Tetrahedrons of N0 give rise to promising quasiparticle band structures with impurity states slightly above the valence band maximum (VBM), which, however, shift to higher energies with increasing negative ionization. The lowest recharging level ɛ(0/−) tends to a value 0.4 eV above the VBM, which is too deep for anything other than a weak p-doping.
Thickness-dependent voltage-modulated magnetism in multiferroic heterostructures
Authors: Shu Li , Li Zheng , Ma Jing , Gao Ya , Gu Lin , Shen Yang , Lin Yuanhua , Nan C. W.
Published: January 2012

The voltage-modulated magnetic behavior in multiferroic Ni/BaTiO3 heterostructures grown on SrTiO3 single crystal substrate was observed by the magneto-optical Kerr effect measurement in an AC modulation technique with synchronizing the frequency of the Kerr signal detector to the low-frequency AC actuation voltage. The results showed coexistence at room-temperature of two magnetoelectric (ME) mechanisms, i.e., strain- and interface charge-mediated couplings. The interaction between the different ME couplings leads to a remarkable thickness-dependent voltage modulation of the magnetic behavior.
Anisotropic electrical transport properties of poly(methyl methacrylate) infiltrated aligned carbon nanotube mats
Authors: Mahanandia P. , Nanda K. K.
Published: January 2012

We report the electrical anisotropic transport properties of poly(methyl methacrylate) infiltrated aligned carbon nanotube mats. The anisotropy in the resistivity increases with decreasing temperature and the conduction mechanism in the parallel and perpendicular direction is different. Magnetoresistance (MR) studies also suggest anisotropic behavior of the infiltrated mats. Though MR is negative, an upturn is observed when the magnetic field is increased. This is due to the interplay of electron weak localization and electron-electron interactions mechanisms. Overall, infiltrated carbon nanotube mat is a good candidate for anisotropically conductive polymer composite and a simple fabrication method has been reported.
Correlating the supercooled liquid region width with the fragility parameter in bulk metallic glasses
Authors: Hu L. , Ye F. , Liang Y. F. , Lin J. P.
Published: January 2012

A linear correlation of fragility parameter D* with supercooled liquid region width ΔTx for Ca-based bulk metallic glasses (BMGs) was revealed. This relationship is found in La- and Zr-based BMGs as well and extended to several glass-forming systems. The origin of this phenomenon lies in the close relation between crystallization and temperature dependence of viscosity. This relationship can be formulated by ΔTx0.33=6.8×10-3×(D*)(Tg0.33)+2(K), indicating that the unique variation of the viscosity with the temperature correlates with the location and width of the supercooled liquid region. Moreover, an approximation of fragility parameter D* for BMGs can be evaluated by the formula.
Computational study on entanglement length and pore size of carbon nanotube buckypaper
Authors: Li Ying , Kröger Martin
Published: January 2012

In this letter, both entanglement length and pore size of carbon nanotube (CNT) buckypaper are studied numerically and found to scale with a characteristic length EI/γ, where EI and γ denote the bending stiffness and binding energy of a CNT, respectively. For EI/γ<40 nm, the CNTs in buckypaper are “interwound” with a short entanglement length and a small pore size. However, when EI/γ>40 nm, CNT “ring”/“racket” structures dominate the buckypaper, exhibiting longer entanglement length and larger pore size. The acquired understanding of microscopic structures allows us to propose that CNT buckypaper with different mechanical properties and pore size can be designed through the choice of EI/γ values.
Theoretical investigation of Fe substitution for Mn in complex hydride YMn2H6
Authors: Takagi Shigeyuki , Miwa Kazutoshi , Ikeshoji Tamio , Matsuo Motoaki , Kano Mika , Orimo Shin-ichi
Published: January 2012

Complex hydride YMn2H6 with a space group Fm3¯m has two sorts of Mn, in which one presents as a divalent cation Mn2+ on the 8c site and the other forms a complex anion [MnH6]5− on the 4a site. We investigate the stabilities of Fe substitutions for a part of Mn atoms on either the site using first-principles calculations. Our results reveal that an Fe atom prefers the 4a occupation, and the origin of this site preference can be understood by the balance of two competing energy gains brought by the 3d bands for either the 4a or 8c site substituted Fe.
Surface enhanced Raman spectroscopy by interfered femtosecond laser created nanostructures
Authors: Wang Chao , Chang Yun-Ching , Yao Jimmy , Luo Claire , (Shizhuo) Yin Stuart , Ruffin Paul , Brantley Christina , Edwards Eugene
Published: January 2012

A type of surface enhanced Raman spectroscopy (SERS) by interfered femtosecond laser created nanostructures on Cu metal is presented. It is found out that finer and more uniform nanostructures (with an average feature size 100 nm or smaller) can be created on Cu metal by interfered femtosecond illumination with a phase mask. Significantly enhanced Raman signal (with an enhancement factor around 863) can be realized by using the nanostructured Cu substrate created by the interfered femtosecond laser illumination. The experimentally measured enhancement factor agrees relatively well with the theoretical analyses. Since the nanostructures can be inscribed in real time and at remote locations by the femtosecond laser inscription, the proposed SERS can be particularly useful for the standoff detection of chemicals.
Long-term retention in organic ferroelectric-graphene memories
Authors: Raghavan Santosh , Stolichnov Igor , Setter Nava , Heron Jean-Savin , Tosun Mahmut , Kis Andras
Published: January 2012

Long-term stability of high- and low-resistance states in full-organic ferroelectrically gated graphene transistors is an essential prerequisite for memory applications. Here, we demonstrate high retention performance for both memory states with fully saturated time-dependence of the graphene channel resistance. This behavior is in contrast with ferroelectric-polymer-gated silicon field-effect-transistors, where the gap between the two memory states continuously decreases with time. Before reaching saturation, the current decays exponentially as predicted by the retention model based on the charge injection into the interface-adjacent layer. The drain current saturation attests to a high quality of the graphene/ferroelectric interface with low density of charge traps.
High (pressure, temperature) phase diagrams of ZnO and AlN from second harmonic generation measurements
Authors: Bayarjargal Lkhamsuren , Winkler Björn
Published: January 2012

The pressure-induced B4 → B1 structural phase boundaries of ZnO and AlN have been determined with the second harmonic generation (SHG) technique at high temperature. The SHG measurements of AlN show that between 15.6 and 18 GPa, the phase boundary has a negative slope of nearly −627 K/GPa, and that below 15.6 GPa, the slope is significantly smaller (−77 K/GPa). ZnO has a phase boundary with a negative slope of nearly −1427 K/GPa around 5.3–6 GPa and −228 K/GPa below 5 GPa. The phase transition pressure of AlN is sensitive to deviatoric stress and varies from 18 to 24.5 GPa.
Dissociation and ionization competing processes for H2+ in intense laser field: Which one is larger?
Authors: He Hai-Xiang , Lu Rui-Feng , Zhang Pei-Yu , Han Ke-Li , He Guo-Zhong
Published: January 2012

Competition between dissociation and ionization of H2+ in intense laser field has been investigated by using an accurate three-dimensional time-dependent wavepacket approach. The disagreement between the experiment and the former one-dimensional theory has been resolved. In a comparison of the calculated results with the available experimental data, a good agreement is reached, not only for the relative probabilities between dissociation and ionization but also for the two-peak structures and the peak energy locations for these two processes.
Silicon introduced effect on resistive switching characteristics of WOX thin films
Authors: Syu Yong-En , Chang Ting-Chang , Tsai Tsung-Ming , Chang Geng-Wei , Chang Kuan-Chang , Tai Ya-Hsiang , Tsai Ming-Jinn , Wang Ying-Lang , Sze Simon M.
Published: January 2012

The switching layer with Si interfusion is investigated to improve the electrical characteristics of WOX resistance random access memory (RRAM). The WOX has attracted extensive attention for RRAM because it can form by converting the surface of the W-plug with a current complementary metal oxide semiconductor (CMOS) compatible thermal oxidation process. In general, the resistance switching behavior of WOX-RRAM devices is unstable because the diverse oxidation state provided the stochastic conduction paths. In this research, the Si interfusion can effectively localize the filament conduction path in WOX resistance switching layer because the tungsten filament path is limited by SiOX in the WSiOX film during the forming process.
Influence of the cluster dimensionality on the binding behavior of CO and O2 on Au13
Authors: Amft Martin , Johansson Börje , Skorodumova Natalia V.
Published: January 2012

We present an ab initio density functional theory study of the binding behavior of CO and O2 molecules to two- and three-dimensional isomers of Au13 in order to investigate the potential catalytic activity of this cluster towards low-temperature CO oxidation. First, we scanned the potential energy surface of Au13 and studied the effect of spin-orbit coupling on the relative stabilities of the 21 isomers we identified. While spin-orbit coupling increases the stability of the three-dimensional more than the two-dimensional isomers, the ground state structure at 0 K remains planar. Second, we systematically studied the binding of CO and O2 molecules onto the planar and three-dimensional structures lowest in energy. We find that the isomer dimensionality has little effect on the binding of CO to Au13. O2, on the other hand, binds significantly to the three-dimensional isomer only. The simultaneous binding of multiple CO molecules decreases the binding energy per molecule. Still, the CO binding remains stronger than the O2 binding. We did not find a synergetic effect due to the co-adsorption of both molecular species. On the three-dimensional isomer, we find O2 dissociation to be exothermic with an dissociation barrier of 1.44 eV.
Label-free multiphoton imaging and photoablation of preinvasive cancer cells
Authors: Zhuo Shuangmu , Chen Jianxin , Wu Guizhu , Zhu Xiaoqin , Jiang Xingshan , Xie Shusen
Published: January 2012

Detection and treatment of early lesions in epithelial tissue offer several possibilities for curing cancer, but it is challenging. Here, we present an optical technique, the combination of multiphoton imaging and absorption, to label-freely detect and ablate preinvasive cancer cells in epithelial tissue. We find that multiphoton imaging can label-freely visualize the principal features of nuclear atypia associated with epithelial precancerous lesions, and the spatial localization of multiphoton absorption can perform targeted ablation of preinvasive cancer cells with micrometer-sized volume precision. These results indicate that this optical technique has the capability to label-freely visualize and remove preinvasive cancer cells in epithelial tissue. This study highlights the potential of this technique as a “seek-and-treat” tool for early lesions in epithelial tissue.
Second-harmonic generation in a periodically poled congruent LiTaO3 sample with phase-tuned nonlinear Cherenkov radiation
Authors: Huang Huang , Huang Cheng-Ping , Zhang Chao , Zhu Ding , Hong Xu-Hao , Lu Jun , Jiang Jian , Wang Qian-Jin , Zhu Yong-Yuan
Published: January 2012

Second harmonic generation (SHG) in a two-dimensional periodically poled congruent LiTaO3 crystal was investigated experimentally. Multiple conical and dotted SHG have been observed, which features phase-tuned Cherenkov radiation, elastic scattering quasi-phase matching process, and random phase matching process. These results are closely connecting with the domain structure and can be utilized as characterization methods for practical purposes.
Excellent carrier mobility of 0.24 cm2/Vs in regioregular poly(3-hexylthiophene) based field-effect transistor by employing octadecyltrimethoxysilane treated gate insulator
Authors: Jiang Yi-Da , Jen Tzu-Hao , Chen Show-An
Published: January 2012

The polymer field-effect transistor based on regioregular poly(3-hexylthiophene) (rr-P3HT) with excellent field-effect mobility up to 0.24 cm2/V s is demonstrated by spin-coating rr-P3HT onto octadecyltrimethoxysilane treated gate insulator followed by thermal annealing of rr-P3HT at 180 °C. This mobility is practically applicable in driving circuits of liquid crystal displays (greater than 0.1 cm2/V s) and close to the highest reported value (0.28 cm2/V s) for rr-P3HT but there a different coating method or dual dielectric layers was used. This impressive mobility can be attributed to the increase in structural ordering of rr-P3HT molecules as supported by x-ray diffraction measurement.
Acoustic dipole radiation based conductivity image reconstruction for magnetoacoustic tomography with magnetic induction
Authors: Sun Xiaodong , Zhang Feng , Ma Qingyu , Tu Juan , Zhang Dong
Published: January 2012

Based on the acoustic dipole radiation theory, a tomograhic conductivity image reconstruction algorithm is developed for the magnetoacoustic tomography with magnetic induction (MAT-MI) in a cylindrical measurement configuration. It has been experimentally proved for a tissue-like phantom that not only the configuration but also the inner conductivity distribution can be reconstructed without any borderline stripe. Furthermore, the spatial resolution also can be improved without the limitation of acoustic vibration. The favorable results have provided solid verification for the feasibility of conductivity image reconstruction and suggested the potential applications of MAT-MI in the area of medical electrical impedance imaging.