bluuebunny/crossref_metadata_2025 huggingface dataset:
The development of nonadjacent dependency learning in natural and artificial languages
Authors: Sandoval Michelle , Gómez Rebecca L.
Published: July 2013

Nonadjacent dependencies occur over one or more intervening units and require learners to track discontinuous sequential relationships. These discontinuous relationships are present at multiple levels in language (e.g., as seen in morphosyntactic dependencies and at the phonological level in vowel harmony). Experiments suggest that these dependencies are acquired using statistical learning mechanisms and that this learning is also affected by perceptual biases. Artificial and natural language studies have shown that infants are sensitive to these statistical regularities but there appear to be developmental constraints on learning. Developmental investigations have also examined how knowledge and processing of the intervening elements affect learning, and whether categories can be acquired using nonadjacent dependency information. WIREs Cogn Sci 2013, 4:511–522. doi: 10.1002/wcs.1244

This article is categorized under:

Linguistics > Language Acquisition

Psychology > Language

Psychology > Learning
Contribution to the Chemistry of (ClC{PPh3}2)Cl, a Precursor of the Carbodiphosphorane C(PPh3)2
Authors: Petz Wolfgang , Neumüller Bernhard
Published: July 2013

The salt (ClC{PPh3}2)Cl (1), formally seen as an addition compound between the carbone C(PPh3)2 and Cl+, reacts with AlBr3 in DCM or 1‐Br‐2‐F‐C6H4 to give the dication (HClC{PPh3}2)2+ with the counterions [AlCl4]– and [AlBr4]–, respectively. If the reaction was carried out in MeNO2 as the solvent the salt (H2C{PPh3}2)Br[AlBr4] was isolated. The dication (HClC{PPh3}2)2+ was also formed from the reaction of 1 with Me3SiOSO2CF3. The protons at the ylidic carbon atoms stem from the solvents. Alternatively, the dication (HClC{PPh3}2)2+ could be obtained more easily upon reacting 1 with HCl in diethyl ether. The compounds were characterized by multi NMR spectroscopy and by X‐ray analyses.
A DFT Study on Estrone – TNT Interaction
Authors: Türker Lemi , Çelik Bayar Çağlar
Published: July 2013

Trinitrotoluene, known as TNT, is a widely used powerful explosive. It is a poisonous material, which injures almost all cells, especially those of liver, bone marrow, and kidney. Estrone is a sex hormone having an electron rich aromatic (phenolic) ring that is capable of forming a π complex with molecules containing an electron deficient π system. This study has focused on investigating the tendency of the complex formation of TNT with estrone. It has been thought that the formation of estrone‐TNT π complex might take place in a human body exposed to acute or prolong period of this hazardous chemical and consequently estrone activities might be impaired. The complex formation reaction was investigated mainly using DFT method with B3LYP/6‐31G(d, p) basis set in gas phase. The existence of π interaction between estrone and TNT was demonstrated by computational spectroscopic analyses (UV/Vis, IR, and 1H NMR techniques). The frontier molecular orbital (HOMO and LUMO) analyses have shown that the considered π complex is very resistant to oxidation with respect to its components, estrone and TNT.
A Vekua‐type linear theory of thick elastic shells
Authors: Zhavoronok S.
Published: July 2013

This paper presents an effective variational formalism of construction of the thick anisotropic linear shell theory of Vekua‐type of an arbitrary order. The dynamic equations are formulated as the Lagrange equations of the second kind, independent from expansion functions. The asymmetric stress tensor is used to obtain the compact form of the dynamic equations similar to the classical shell theories. The proposed approach allows one for computer‐aided derivation of all equations using computer algebra software supporting main tensor operations. Some solutions of test problems are presented.
Finding all flux vacua in an explicit example
Authors: Martínez-Pedrera Danny , Mehta Dhagash , Rummel Markus , Westphal Alexander
Published: June 2013

Abstract

We explicitly construct all supersymmetric flux vacua of a particular Calabi-Yau compactification of type IIB string theory for a small number of flux carrying cycles and a given D3-brane tadpole. The analysis is performed in the large complex structure region by using the polynomial homotopy continuation method, which allows to find all stationary points of the polynomial equations that characterize the supersymmetric vacuum solutions. The number of vacua as a function of the D3 tadpole is in agreement with statistical studies in the literature. We calculate the available tuning of the cosmological constant from fluxes and extrapolate to scenarios with a larger number of flux carrying cycles. We also verify the range of scales for the moduli and gravitino masses recently found for a single explicit flux choice giving a Kähler uplifted de Sitter vacuum in the same construction.
Naturalness of light neutralino dark matter in pMSSM after LHC, XENON100 and Planck data
Authors: Bœhm Céline , Bhupal Dev P. S. , Mazumdar Anupam , Pukartas Ernestas
Published: June 2013

Abstract

We examine the possibility of a light (below 46 GeV) neutralino dark matter (DM) candidate within the 19-parameter phenomenological Minimal Supersymmetric Standard Model (pMSSM) in the light of various recent experimental results, especially from the LHC, XENON100, and Planck. We also study the extent of electroweak fine-tuning for such a light neutralino scenario in view of the null results from the searches for supersymmetry so far. Using a Markov Chain Monte Carlo likelihood analysis of the full pMSSM parameter space, we find that a neutralino DM with mass ≳ 10 GeV can in principle still satisfy all the existing constraints. Our light neutralino solutions can be broadly divided into two regions: (i) The solutions in the 10–30 GeV neutralino mass range are highly fine-tuned and require the existence of light selectrons (below 100 GeV) in order to satisfy the observed DM relic density. We note that these are not yet conclusively ruled out by the existing LEP/LHC results, and a dedicated analysis valid for a non-unified gaugino mass spectrum is required to exclude this possibility. (ii) The solutions with low fine-tuning are mainly in the 30–46 GeV neutralino mass range. However, a major portion of it is already ruled out by the latest XENON100 upper limits on its spin-independent direct detection cross section, and the rest of the allowed points are within the XENON1T projected limit. Thus, we show that the allowed MSSM parameter space for a light neutralino DM below the LEP limit of 46 GeV, possible in supersymmetric models without gaugino mass unification, could be completely accessible in near future. This might be useful in view of the recent claims for positive hints of a DM signal in some direct detection experiments.
Time‐specific effect of prenatal stressful life events on gestational weight gain
Authors: Zhu Peng , Huang Wen , Hao Jia‐Hu , Huang Kun , Jiang Xiao‐Min , Tao Fang‐Biao
Published: June 2013

Objective

To investigate the time‐specific effect of maternal exposure to prenatal stressful life events (SLEs) on gestational weight gain (GWG) and to determine whether pre‐pregnancy body mass index (BMI) modifies the effect.

Methods

Between March and November 2008, data were collected from 1800 pregnant women who received prenatal check‐ups in Hefei, China, after 32 completed weeks of gestation. Participants completed a structured interview on demographic characteristics and a checklist of SLEs during different stages of pregnancy. GWG during pregnancy was determined by self‐reported pre‐pregnancy weight and measured weight at delivery.

Results

There was a significant dose–response relationship between prenatal SLEs in the first, but not the second or third, trimester and GWG. For each 1‐unit increase in SLEs during the first trimester, there was a reduction in GWG of approximately 0.497 kg (95% confidence interval, 0.176–0.817 kg). After stratification by pre‐pregnancy BMI, a significant negative association between SLEs in the first trimester and GWG was observed among women with pre‐pregnancy normal (β = − 0.796; 95% CI, − 1.291 to − 0.301) and low (β = − 1.066; 95% CI, − 2.180 to − 0.048) weight.

Conclusion

The effect of prenatal SLEs on GWG depends on the timing of maternal exposure to stress and varies according to pre‐pregnancy BMI.
Bibliotheca marsdeniana philologica et orientalis
Authors: Marsden William
Published: July 2013

Amassed over a forty-year career, first with the East India Company in Sumatra and later with the Admiralty as its First Secretary, William Marsden's library, as revealed in this catalogue of 1827, was an invaluable collection. An expert in Asian languages, Marsden (1754–1836) published his catalogue to provide a basis for study into comparative linguistics and oriental literature. This work provides an insight into both the practice of book-collecting in the period, and the variety of works published throughout the world. It lists texts on travel, medicine and linguistics, as well as works of literature and religion, including some extremely rare Bibles, and a possibly unique copy of the Book of Genesis in the Algonquin language. The library itself was donated to King's College, London, in 1835 and is now shared by King's College and the School of Oriental and African Studies at the University of London.
G. Lejeune Dirichlet's Werke
Authors: Dirichlet Peter Gustav Lejeune
Published: July 2013

The great nineteenth-century mathematician Peter Gustav Lejeune Dirichlet (1805–59) studied in Paris, coming under the influence of scholars including Fourier and Legendre. He then taught at Berlin and Göttingen universities, where he was the successor to Gauss and mentor to Riemann and Dedekind. His achievements include the first satisfactory proof of the convergence of Fourier series under appropriate conditions, and the theorem on primes in arithmetic progression which was, at the same time, the foundation of analytic number theory and one of its greatest achievements. He also did important work on Laplace's equation, the theory of series and many other topics. This two-volume collection of his works, published 1889–97, was compiled by Leopold Kronecker (1823–91). Volume 1 contains works published by Dirichlet up to 1843, together with a related 1846 essay.
Oeuvres complètes de Niels Henrik Abel
Authors: Abel Niels Henrik
Published: July 2013

Niels Henrik Abel (1802–29) was one of the most prominent mathematicians in the first half of the nineteenth century. His pioneering work in diverse areas such as algebra, analysis, geometry and mechanics has made the adjective 'abelian' a commonplace in mathematical writing. These collected works, first published in two volumes in 1881 after careful preparation by the mathematicians Ludwig Sylow (1832–1918) and Sophus Lie (1842–99), contain some of the pillars of mathematical history. Volume 1 includes perhaps the most famous of Abel's results, namely his proof of the 'impossibility theorem', which states that the general fifth-degree polynomial is unsolvable by algebraic means. Also included in this volume is Abel's 'Paris memoir', which contains his many fundamental results on transcendental functions - in particular on elliptic integrals, elliptic functions, and what are known today as abelian integrals.
Wissenschaftliche Abhandlungen
Authors: Boltzmann Ludwig
Published: July 2013

The Austrian physicist Ludwig Eduard Boltzmann (1844–1906), educated at the University of Vienna, was appointed professor of mathematical physics at the University of Graz in 1869 at the age of only twenty-five. Boltzmann did important work in the fields of statistical mechanics and statistical thermodynamics; for instance, he contributed to the kinetic theory concerned with molecular speeds in gas. Boltzmann also promoted atomic theory, which at the time was still highly controversial. He was a member of the Imperial Austrian Academy of Sciences from 1885 and became a member of the Royal Swedish Academy of Sciences in 1888. This three-volume work, prepared in 1909 by the physicist Fritz Hasenöhrl, one of Boltzmann's students, comprises all his academic publications from 1865 to 1905. Volume 3 contains papers from 1882 to 1905, including work on gas diffusion and thermodynamics.
A Dictionary of Irish Artists
Authors: Strickland Walter
Published: July 2013

First published in 1913, this highly illustrated two-volume work was intended to give as full an account as possible of the lives and works of painters, sculptors and engravers in Ireland from the earliest times to the nineteenth century. Until then, the history of Irish art had been largely neglected, so this project was an extensive undertaking for Walter George Strickland (1850–1928), who became Director of the National Gallery of Ireland. It took him two decades to compile, and involved accessing private collections, corresponding with experts, meeting with the artists' descendants, and consulting letters, diaries and notes relating to their works. Volume 2 covers artists with surnames beginning L to Z. Each entry contains biographical information on the artist and details of their works, with portraits and examples provided in hundreds of plates. This unique reference work remains of great interest to art historians and historians of Ireland.
History of the War in France and Belgium, in 1815
Authors: Siborne William
Published: July 2013

Originally published in 1844, this two-volume work by William Siborne (1797–1830) represented the first major history of the Waterloo Campaign that was based on eyewitness accounts. Although Siborne, an infantry officer, had not served in the campaign himself, he did write to scores of officers who had, and their replies provided him with information he later used to construct the famous but controversial model of the field at Waterloo, which earned him the enmity of the Duke of Wellington (largely because Siborne's view of events conflicted with the Duke's). Siborne used much of the material for this book, which covers the entire campaign from Napoleon's escape from Elba in February 1815, through the battles of Ligny, Quatre Bras and Waterloo, right up to the Allies' entry into Paris in July. The maps published in a third volume can be viewed online. Volume 2 covers the greater part of the Battle of Waterloo and its aftermath.
RECONSIDERING “TOTAL” FAILURE
Authors: Wilmot-Smith Frederick
Published: July 2013

The law has long recognised a right to recover an enrichment transferred on a consideration which has failed. However, the consideration has to fail totally. Much ink has been spilled arguing that the limit is a bad one. Less has been written about quite what a total failure of consideration actually is. In this paper, it is argued that the best understanding of the total failure rule is that it prevents restitution when the failure is insubstantial; only substantial failures justify restitution. This shows that the limit is integral to the justification of the award of restitution.
Brain anatomy of autism spectrum disorders II. Focus on amygdala
Authors: Bellani M. , Calderoni S. , Muratori F. , Brambilla P.
Published: July 2013

This brief review encompasses the key findings of structural Magnetic Resonance Imaging (sMRI) research on amygdala volume in autism spectrum disorders (ASD). We also highlight the possible correlation between the autistic behavioural phenotype and amygdala alteration.
Evaluation and improvement in the accuracy of a charge-coupled-device-based pyrometer for temperature field measurements of continuous casting billets
Authors: Bai Haicheng , Xie Zhi , Zhang Yuzhong , Hu Zhenwei
Published: June 2013

This paper presents a radiometric high-temperature field measurement model based on a charge-coupled-device (CCD). According to the model, an intelligent CCD pyrometer with a digital signal processor as the core is developed and its non-uniformity correction algorithm for reducing the differences in accuracy between individual pixel sensors is established. By means of self-adaptive adjustment for the light-integration time, the dynamic range of the CCD is extended and its accuracy in low-temperature range is improved. The non-uniformity correction algorithm effectively reduces the accuracy differences between different pixel sensors. The performance of the system is evaluated through a blackbody furnace and an integrating sphere, the results of which show that the dynamic range of 400 K is obtained and the accuracy in low temperature range is increased by 7 times compared with the traditional method based on the fixed light-integration time. In addition, the differences of accuracy between the on-axis pixel and the most peripheral pixels are decreased from 19.1 K to 2.8 K. Therefore, this CCD pyrometer ensures that the measuring results of all pixels tend to be equal-accuracy distribution across the entire measuring ranges. This pyrometric system has been successfully applied to the temperature field measurements in continuous casting billets.
Far infrared stimulated emission from the ns and nf Rydberg states of NO
Authors: Furukawa Hiroki , Araki Mitsunori , Umeki Hiroya , Tsukiyama Koichi
Published: June 2013

We report directional far-infrared emission from the υ = 0 vibrational levels of the 9sσ, 10sσ, 11sσ, 9f, and 10f Rydberg states of NO in the gas phase. The emission around 28 and 19 μm from the 9f state was identified as the downward 9f → 8g and subsequent 8g → 7f cascade transitions, respectively. The emission around 38 and 40 μm from the 10f state was identified as the 10f → 9g and 10f → 9dσπ transition, respectively. Following the excitation of the 9sσ, 10sσ, and 11sσ states, the emission around 40, 60, and 83 μm was assigned as the 9sσ → 8pσ, 10sσ → 9pσ, and 11sσ → 10pσ transitions, respectively. In addition to these emission systems originated from the laser-prepared levels, we found the emission bands from the 8f, 9f, and 10f states which are located energetically above the 9sσ, 10sσ, and 11sσ states, respectively. This observation suggests that the upward 8f ← 9sσ, 9f ← 10sσ, and 10f ← 11sσ optical excitation occurs. Since the energy differences between nf and (n + 1)sσ states correspond to the wavelength longer than 100 μm, the absorption of blackbody radiation is supposed to be essential for these upward transitions.
Stability limits of n-nonane calculated from molecular dynamics interface simulations
Authors: Braun S. , Imre A. R. , Kraska T.
Published: June 2013

Based on molecular dynamics simulation of the vapor-liquid interface, the classical thermodynamic spinodal for n-nonane is estimated using an earlier developed method. The choice of n-nonane as investigated molecule originates from the question whether a deviation from the spherical symmetry of a molecule affects the prediction of the stability limit data. As a result, we find that the estimated stability limit data for n-nonane are consistent within the experimental data available for the homologous series of the n-alkanes. It turns out that the slight alignment of the molecules parallel to the interface reported in the literature does not affect the method of transferring interface properties to the bulk phase stability limit.
Cu2ZnSnSe4 films from binary precursors
Authors: Volobujeva O. , Mellikov E. , Timmo K. , Danilson M. , Bereznev S.
Published: June 2013

The precursor stacked films of consistent binary chalcogenides (ZnSe, SnSe, CuSe) were deposited onto molybdenum covered soda-lime glass substrates by vacuum evaporation. Thermal treatments in SnSe2 or elemental selenium containing atmospheres were used for copper-zinc-tin-sulphide (CZTSe) formation. XPS investigations confirm the formation of CZTSe films homogeneous in bulk in both selenization atmospheres. At the same time, surface area composition of films selenized in Se and SnSe2 differed and the surface layer of CTZSe films selenized in SnSe2 atmosphere was tin–rich, containing separate phases of Se and SnSe2. The etching of CZTSe films with 1% Br2-MeOH (bromine in methanol) at the rate of 75 nm/s removed mainly metals from the surface films and left precipitates of Se on the surface. Solar cell structures with the efficiency of about 3% were developed using selenized and etched films.
A Fokker–Planck based kinetic model for diatomic rarefied gas flows
Authors: Gorji M. Hossein , Jenny Patrick
Published: June 2013

A Fokker–Planck based kinetic model is presented here, which also accounts for internal energy modes characteristic for diatomic gas molecules. The model is based on a Fokker–Planck approximation of the Boltzmann equation for monatomic molecules, whereas phenomenological principles were employed for the derivation. It is shown that the model honors the equipartition theorem in equilibrium and fulfills the Landau–Teller relaxation equations for internal degrees of freedom. The objective behind this approximate kinetic model is accuracy at reasonably low computational cost. This can be achieved due to the fact that the resulting stochastic differential equations are continuous in time; therefore, no collisions between the simulated particles have to be calculated. Besides, because of the devised energy conserving time integration scheme, it is not required to resolve the collisional scales, i.e., the mean collision time and the mean free path of molecules. This, of course, gives rise to much more efficient simulations with respect to other particle methods, especially the conventional direct simulation Monte Carlo (DSMC), for small and moderate Knudsen numbers. To examine the new approach, first the computational cost of the model was compared with respect to DSMC, where significant speed up could be obtained for small Knudsen numbers. Second, the structure of a high Mach shock (in nitrogen) was studied, and the good performance of the model for such out of equilibrium conditions could be demonstrated. At last, a hypersonic flow of nitrogen over a wedge was studied, where good agreement with respect to DSMC (with level to level transition model) for vibrational and translational temperatures is shown.
Large area single crystal (0001) oriented MoS2
Authors: Laskar Masihhur R. , Ma Lu , Kannappan Santhakumar , Sung Park Pil , Krishnamoorthy Sriram , Nath Digbijoy N. , Lu Wu , Wu Yiying , Rajan Siddharth
Published: June 2013

Layered metal dichalcogenide materials are a family of semiconductors with a wide range of energy band gaps and properties, the potential for exciting physics and technology applications. However, obtaining high crystal quality thin films over a large area remains a challenge. Here we show that chemical vapor deposition (CVD) can be used to achieve large area single crystal Molybdenum Disulfide (MoS2) thin films. Growth temperature and choice of substrate were found to critically impact the quality of film grown, and high temperature growth on (0001) oriented sapphire yielded highly oriented single crystal MoS2 films. Films grown under optimal conditions were found to be of high structural quality from high-resolution X-ray diffraction, transmission electron microscopy, and Raman measurements, approaching the quality of reference geological MoS2. Photoluminescence and electrical measurements confirmed the growth of optically active MoS2 with a low background carrier concentration, and high mobility. The CVD method reported here for the growth of high quality MoS2 thin films paves the way towards growth of a variety of layered 2D chalcogenide semiconductors and their heterostructures.
Simulations and experiments of short intense envelope solitons of surface water waves
Authors: Slunyaev A. , Clauss G. F. , Klein M. , Onorato M.
Published: June 2013

The problem of existence of stable nonlinear groups of gravity waves in deep water is considered by means of laboratory and numerical simulations with the focus on strongly nonlinear waves. Wave groups with steepness up to Acrωm2/g ≈ 0.30 are reproduced in laboratory experiments (Acr is the wave crest amplitude, ωm is the mean angular frequency, and g is the gravity acceleration). We show that the groups remain stable and exhibit neither noticeable radiation nor structural transformation for more than 60 wavelengths or about 15-30 group lengths. These solitary wave patterns differ from the conventional envelope solitons, as only a few individual waves are contained in the group. Very good agreement is obtained between the laboratory results and numerical simulations of the potential Euler equations. The envelope soliton solution of the nonlinear Schrödinger equation is shown to be a reasonable first approximation for specifying the wave-maker driving signal. The short intense envelope solitons possess vertical asymmetry similar to regular Stokes waves with the same frequency and crest amplitude. Nonlinearity is found to have remarkably stronger effect on the speed of envelope solitons in comparison to the nonlinear correction to the Stokes wave velocity.
Modified diffusion equation for the wormlike-chain statistics in curvilinear coordinates
Authors: Liang Qin , Li Jianfeng , Zhang Pingwen , Chen Jeff Z. Y.
Published: June 2013

One of the essential physical quantities used to study the conformation and structure of polymers is the so-called propagator in polymer theories. On the basis of the wormlike-chain statistical-physics model, we derive the partial diffusion equation that the propagator satisfies, for a curvilinear coordinate system. As it turns out, an additional term exists, that couples the rotating local coordinate frame with an orientation differential operator; this term has not been previously documented. In addition, for a wormlike chain moving on a curved surface, the external-field term needs to be supplemented by a surface curvature energy penalty.
Effective electrodiffusion equation for non-uniform nanochannels
Authors: Marconi Umberto Marini Bettolo , Melchionna Simone , Pagonabarraga Ignacio
Published: June 2013

We derive a one-dimensional formulation of the Planck-Nernst-Poisson equation to describe the dynamics of a symmetric binary electrolyte in channels whose section is nanometric and varies along the axial direction. The approach is in the spirit of the Fick-Jacobs diffusion equation and leads to a system of coupled equations for the partial densities which depends on the charge sitting at the walls in a non-trivial fashion. We consider two kinds of non-uniformities, those due to the spatial variation of charge distribution and those due to the shape variation of the pore and report one- and three-dimensional solutions of the electrokinetic equations.
Interfacial growth as a model of tube-width heterogeneities in concentrated solutions of stiff polymers
Authors: Sharma Rati , Cherayil Binny J.
Published: June 2013

Recent experimental measurements of the distribution P(w) of transverse chain fluctuations w in concentrated solutions of F-actin filaments [B. Wang, J Guan, S. M. Anthony, S. C. Bae, K. S. Schweizer, and S. Granick, Phys. Rev. Lett. 104, 118301 (2010)10.1103/PhysRevLett.104.118301; J. Glaser, D. Chakraborty, K. Kroy, I. Lauter, M. Degawa, N. Kirchgessner, B. Hoffmann, R. Merkel, and M. Giesen, Phys. Rev. Lett. 105, 037801 (2010)]10.1103/PhysRevLett.105.037801 are shown to be well-fit to an expression derived from a model of the conformations of a single harmonically confined weakly bendable rod. The calculation of P(w) is carried out essentially exactly within a path integral approach that was originally applied to the study of one-dimensional randomly growing interfaces. Our results are generally as successful in reproducing experimental trends as earlier approximate results obtained from more elaborate many-chain treatments of the confining tube potential.
Mechanical properties of hydrogenated bilayer graphene
Authors: Andrew R. C. , Mapasha R. E. , Chetty N.
Published: June 2013

Using first principle methods, we study the mechanical properties of monolayer and bilayer graphene with 50% and 100% coverage of hydrogen. We employ the vdW-DF, vdW-DF-C09x, and vdW-DF2-C09x van der Waals functionals for the exchange correlation interactions that give significantly improved interlayer spacings and energies. We also use the PBE form for the generalized gradient corrected exchange correlation functional for comparison. We present a consistent theoretical framework for the in-plane layer modulus and the out-of-plane interlayer modulus and we calculate, for the first time, these properties for these systems. This gives a measure of the change of the strength properties when monolayer and bilayer graphene are hydrogenated. Moreover, comparing the relative performance of these functionals in describing hydrogenated bilayered graphenes, we also benchmark these functionals in how they calculate the properties of graphite.
Effect of lithium on the properties of a liquid crystal formed by sodium dodecylsulphate and decanol in aqueous solution
Authors: Bahamonde-Padilla V. E. , Espinoza Javier , Weiss-López B. E. , Cascales J. J. López , Montecinos R. , Araya-Maturana R.
Published: July 2013

Understanding the molecular interactions that rule the physicochemical properties of molecular assemblies is of particular interest when trying to explain the behavior of much more complicated systems, such as the cell membranes. This work was devoted to study a discotic nematic lyotropic liquid crystal, formed by sodium dodecylsulphate (3% SDS-d25) and decanol (20% DeOH-α-d2), dissolved in aqueous solutions (0.1% D2O) of Na2SO4 or Li2SO4. The average size of the aggregates was estimated using fluorescence quenching experiments, and their dynamics were studied by measuring the 2H-NMR quadrupole splitting (ΔνQ) and the longitudinal relaxation times (T1) of the deuterated species. To provide an atomic insight into these assemblies, molecular dynamics simulations of the systems were carried out with atomic detail. As a previous step in this study, a reparameterization of the standard GROMOS 87 force field was required to perform the equilibrated simulations and to prevent instabilities emerging during the simulations. Finally, an excellent agreement between simulation and experimental data was obtained. In addition, variations in the long range electrostatic interactions at the aggregate/solution interface, the orientation and the reorientational relaxation time of the water dipole, the translational diffusion coefficient of sodium ions, and the amphiphile-counterion coordination associated with the presence of Li+ in the solution were other key aspects investigated to explain the variation in the quadrupole splittings (ΔνQ) in the presence of lithium in solution.
Modulational instability in crossing sea states over finite depth water
Authors: Kundu Sumana , Debsarma S. , Das K. P.
Published: June 2013

Nonlinear evolution equations are derived in a situation of crossing sea states characterized by water waves having two different spectral peaks. The nonlinear evolution equations derived here are valid for any water depth except for shallow water depth case. These evolution equations are then employed to study the instability properties of two Stokes wave trains considering both unidirectional and bidirectional perturbations. Figures have been plotted showing the growth rate of instability for various depths of water and for different values of the angle of interaction of the two wave systems. All the figures serve as an evidence to the fact that freak waves can be formed as a result of modulational instability in crossing sea states over finite depth water. It is observed that the growth rate of instability in crossing sea states situation over finite depth water is much higher than that for infinite depth case and it increases with the decrease of the depth of water.
Characterization of ultrananocrystalline diamond microsensors for in vivo dopamine detection
Authors: Arumugam Prabhu U. , Zeng Hongjun , Siddiqui Shabnam , Covey Dan P. , Carlisle John A. , Garris Paul A.
Published: June 2013

We show the technical feasibility of coating and micro patterning boron-doped ultrananocrystalline diamond (UNCD®) on metal microwires and of applying them as microsensors for the detection of dopamine in vivo using fast-scan cyclic voltammetry. UNCD electrode surface consistently generated electrochemical signals with high signal-to-noise ratio of >800 using potassium ferrocyanide-ferricyanide redox couple. Parylene patterned UNCD microelectrodes were effectively applied to detect dopamine reliably in vitro using flow injection analysis with a detection limit of 27 nM and in the striatum of the anesthetized rat during electrical stimulation of dopamine neurons.
Tight-binding description of graphyne and its two-dimensional derivatives
Authors: Zheng Jia-Jia , Zhao Xiang , Zhang Shengbai B. , Gao Xingfa
Published: June 2013

We investigated band structures of α-graphyne and its derivative two-dimensional carbon compounds (2DCCs) via tight-binding approximations with “two-site” and “all-atom” models. The renormalized “two-site” model captures the band-gap features of α-graphyne and 2DCCs. This model suggests ways of tuning the band gaps of graphynes, namely, by adding adatoms or substituting the vertex sp2 carbons with heteroatom. Because the “two-site” model cannot accurately reproduce first-principles results over a large range of wave vectors, we derived an “all-atom” model, which includes all pz orbitals in a unit cell. All atom tight-binding calculations show improved performances in describing the DFT band structures, and reveal that the flat bands in DFT band structures are mainly ascribed to the pz orbitals of the edge carbons. The results will help to uncover the underlying mechanisms of the band features of graphyne and 2DCCs and to design other graphyne- or graphdiyne-based 2DCCs for applications in the future.
Helical swimming in Stokes flow using a novel boundary-element method
Authors: Liu Bin , Breuer Kenneth S. , Powers Thomas R.
Published: June 2013

We apply the boundary-element method to Stokes flows with helical symmetry, such as the flow driven by an immersed rotating helical flagellum. We show that the two-dimensional boundary integral method can be reduced to one dimension using the helical symmetry. The computational cost is thus much reduced while spatial resolution is maintained. We review the robustness of this method by comparing the simulation results with the experimental measurement of the motility of model helical flagella of various ratios of pitch to radius, along with predictions from resistive-force theory and slender-body theory. We also show that the modified boundary integral method provides reliable convergence if the singularities in the kernel of the integral are treated appropriately.
Building a kinetic Monte Carlo model with a chosen accuracy
Authors: Bhute Vijesh J. , Chatterjee Abhijit
Published: June 2013

The kinetic Monte Carlo (KMC) method is a popular modeling approach for reaching large materials length and time scales. The KMC dynamics is erroneous when atomic processes that are relevant to the dynamics are missing from the KMC model. Recently, we had developed for the first time an error measure for KMC in Bhute and Chatterjee [J. Chem. Phys. 138, 084103 (2013)10.1063/1.4792439]. The error measure, which is given in terms of the probability that a missing process will be selected in the correct dynamics, requires estimation of the missing rate. In this work, we present an improved procedure for estimating the missing rate. The estimate found using the new procedure is within an order of magnitude of the correct missing rate, unlike our previous approach where the estimate was larger by orders of magnitude. This enables one to find the error in the KMC model more accurately. In addition, we find the time for which the KMC model can be used before a maximum error in the dynamics has been reached.
Effects of surface oxide formation on germanium nanowire band-edge photoluminescence
Authors: Minaye Hashemi Fatemeh Sadat , Thombare Shruti , Morral Anna Fontcuberta i , Brongersma Mark L. , McIntyre Paul C.
Published: June 2013

The effect of intentional surface oxide formation on band-edge photoluminescence (PL) of Ge nanowires was investigated. Thermal oxidation in molecular O2 was used to produce a surface oxide layer on assemblies of single crystal nanowires grown by the vapor-liquid-solid method. With increasing oxidation of the wires, the band-edge PL associated with the indirect gap transition becomes more intense. X-ray photoelectron spectroscopy confirms the formation of an increasingly GeO2-like surface oxide under annealing conditions that enhance the indirect-gap PL, consistent with surface oxide passivation of nonradiative recombination centers initially present on the nanowire surface.
Note: Ion source design for ion trap systems
Authors: Noriega J. R. , Quevedo M. , Gnade B. , Vasselli J.
Published: June 2013

A small plasma (glow discharge) based ion source and circuit are described in this work. The ion source works by producing a high voltage pulsed discharge between two electrodes in a pressure range of 50–100 mTorr. A third mesh electrode is used for ion extraction. The electrodes are small stainless steel screws mounted in a MACOR ionization chamber in a linear arrangement. The electrode arrangement is driven by a circuit, design for low power operation. This design is a proof of concept intended for applications on small cylindrical ion traps.
Resonance running hologram velocity nonlinearity dependence upon light intensity in photorefractive crystals
Authors: de Oliveira Ivan , Carvalho Jesiel F. , Frejlich Jaime
Published: June 2013

We report on the nonlinear relation between the resonance hologram velocity and the recording light irradiance in fringe-locked running hologram experiments carried out on a nominally undoped photorefractive Bi12TiO20 crystal using 532 nm wavelength laser light. Such nonlinearity is due to the dependence of the material diffusion length on the light irradiance. Experimental data show a good agreement with the theoretical equations thus supporting the mathematical model here reported and allowing to compute the quantum efficiency for photoelectron generation, the dependence of the diffusion length upon the recorded light irradiance, and the far from saturation diffusion length.
A droplet manipulation on a liquid crystal and polymer composite film as a concentrator and a sun tracker for a concentrating photovoltaic system
Authors: Tsou Yu-Shih , Chang Kai-Han , Lin Yi-Hsin
Published: June 2013

We demonstrate a droplet manipulation on a liquid crystal and polymer composite film (LCPCF) as a concentrator and a sun tracker for a concentrating photovoltaic (CPV) system with a steady output electric power. The CPV system adopts a liquid lens on LCPCF whose curvature is not only tunable but position is also bistably switchable based on liquid crystal orientations on LCPCF. The change of curvature of the liquid lens results in a tunable concentration ratio which helps to increase photocurrent at a low illumination and prevent the effect of the series resistance at a high illumination. Moreover, the change of the position of the liquid lens helps to track sun owing to sun movement. Therefore, the output power of such a system is steady no matter the sunlight condition and the angle of incident light. The operating principles and experiments are investigated. The concept in this paper can be extended to design optical components for obtaining steady output power of the solar cell at indoor or outdoor use and also tracking sunlight.
Mechanical properties of FeCo magnetic particles-based Sn-Ag-Cu solder composites
Authors: Xu Siyang , Prasitthipayong Anya , Pickel Andrea D. , Habib Ashfaque H. , McHenry Michael E.
Published: June 2013

We demonstrate magnetic nanoparticles (MNPs) in enabling lead-free solder reflow in RF fields and improved mechanical properties that impact solder joint reliability. Here, we report on Sn-Ag-Cu (SAC) alloys. SAC solder-FeCo MNP composites with 0, 1, 2, 3, and 4 wt. % FeCo MNP and the use of AC magnetic fields to achieve localized reflow. Electron microscopy of the as-reflowed samples show a decrease in the volume of Sn dendrite regions as well as smaller and more homogeneously dispersed Ag3Sn intermetallic compounds (IMCs) with increasing MNP concentrations. Mechanical properties of the composites were measured by nanoindentation. In pure solder samples and solder composites with 4 wt. % MNP, hardness values increased from 0.18 GPa to 0.20 GPa and the modulus increased from 39.22 GPa to 71.22 GPa. The stress exponent, reflecting creep resistance, increased from 12.85 of pure solder to 16.47 for solder composites with 4 wt. % MNP. Enhanced mechanical properties as compared with the as-prepared solder joints are explained in terms of grain boundary and dispersion strengthening resulting from the microstructural refinement.
Performance and characteristics of double layer porous silicon oxide resistance random access memory
Authors: Tsai Tsung-Ming , Chang Kuan-Chang , Zhang Rui , Chang Ting-Chang , Lou J. C. , Chen Jung-Hui , Young Tai-Fa , Tseng Bae-Heng , Shih Chih-Cheng , Pan Yin-Chih , Chen Min-Chen , Pan Jhih-Hong , Syu Yong-En , Sze Simon M.
Published: June 2013

A bilayer resistive switching memory device with an inserted porous silicon oxide layer is investigated in this letter. Compared with single Zr:SiOx layer structure, Zr:SiOx/porous SiOx structure outperforms from various aspects, including low operating voltages, tighter distributions of set voltage, higher stability of both low resistance state and high resistance state, and satisfactory endurance characteristics. Electric field simulation by comsolTM Multiphysics is applied, which corroborates that intensive electric field around the pore in porous SiOx layer guides the conduction of electrons. The constraint of conduction path leads to better stabilization and prominent performance of bilayer resistive switching devices.
Electronic and structural properties of carbon nanotubes modulated by external strain
Authors: Su Wan-Sheng
Published: June 2013

Responses of work functions to uniaxial strain on infinite-length single-walled armchair (AC) [(2, 2) and (7, 7)] and zigzag (ZZ) [(3, 0) and (12, 0)] carbon nanotubes (CNTs) are investigated based on density functional theory. It is found that as strain increases, the work function of ZZ (3, 0) tubes decreases monotonically from 6.2 to 5.7 eV, whereas that of AC (2, 2) tubes varies between 4.6 and 5.3 eV in a somewhat complicated manner. For ZZ (12, 0) and AC (7, 7) tubes with large diameters, the work function of ZZ (12, 0) changes almost linearly from 4.2 to 4.8 eV, while for AC (7, 7) work function values grow monotonically from 4.1 to 4.7 eV. The energy band changes provide a qualitative understanding of how work function is affected by the uniaxial strain. Our findings are helpful not only for understanding the electronic properties of strained CNTs but also open the possibility of potential applications in CNT-based electronics devices.
Submicron mapping of strain distributions induced by three-dimensional through-silicon via features
Authors: Murray Conal E. , Graves-Abe T. , Robison R. , Cai Z.
Published: June 2013

Strain distributions within the active layer of a silicon-on-insulator substrate induced by through-silicon via (TSV) structures were mapped using x-ray microbeam diffraction. The interaction region of the out-of-plane strain, ε33, from a TSV feature containing copper metallization extended approximately 6 μm from the TSV outer edge for circular and annular geometries. Measurements conducted on identical TSV structures without copper reveal that strain fields generated by the liner materials extend a similar distance and with comparable magnitude as those with copper. FEM-based simulations show the total interaction region induced by the TSV can extend farther than that of ε33.
Diffusive capacitance in space charge limited organic diodes: Analysis of peak in capacitance-voltage characteristics
Authors: Tripathi Durgesh C. , Mohapatra Y. N.
Published: June 2013

One of the significant features of capacitance-voltage (C-V) characteristics of organic diodes is the occurrence of a peak near the built-in voltage due to competition between diffusion and drift of carriers. The voltage dependence of the rise in small signal capacitance prior to the peak is modulated by the transit time of the carriers and leads to a linear 1/C2/3 vs V dependence, which has been demonstrated both through simulation, and experiments using small molecule (m-MTDATA) based diodes. The utility of such analysis in obtaining threshold voltages significant for characterization of organic diodes has been demonstrated.
Optical constants and spatial uniformity of thermally grown oxide layer of custom, induced-junction, silicon photodiodes for a predictable quantum efficient detector
Authors: White M. , Lolli L. , Brida G. , Gran J. , Rajteri M.
Published: June 2013

We have investigated the optical properties of self-induced inversion-layer silicon photodiodes using spectroscopic ellipsometric measurement techniques. We report a self-consistent data set and dispersion relation for the optical constants of the thermally grown oxide layer. The oxide layer thickness and spatial uniformity of a series of custom manufactured 22 mm × 11 mm rectangular diodes are evaluated. These photodiodes are used in a light trapping arrangement and exhibit predictable quantum efficiency and thus, predictable spectral responsivity. For comparison, we report measurements of the absolute spatial uniformity of the oxide layer on commercial “S6337” and “S1337” radiometric quality photodiodes.
Spatio-temporal evolution of the H → L back transition
Authors: Miki K. , Diamond P. H. , Schmitz L. , McDonald D. C. , Estrada T. , Gürcan Ö. D. , Tynan G. R.
Published: June 2013

Since ITER will operate close to threshold and with limited control, the H → L back transition is a topic important for machine operations as well as physics. Using a reduced mesoscale model [Miki et al., Phys. Plasmas 19, 092306 (2012)], we investigate ELM-free H → L back transition dynamics in order to isolate transport physics effects. Model studies indicate that turbulence spreading is the key process which triggers the back transition. The transition involves a feedback loop linking turbulence and profiles. The I-phase appears during the back transition following a slow power ramp down, while fast ramp-downs reveal a single burst of zonal flow during the back transition. The I-phase nucleates at the pedestal shoulder, as this is the site of the residual turbulence in H-mode. Hysteresis in the profile gradient scale length is characterized by the Nusselt number, where Nu=χi,turb/χi,neo. Relative hysteresis of temperature gradient vs density gradient is sensitive to the pedestal Prandtl number, where Prped=Dped/χi,neo. We expect the H-mode to be somewhat more resilient in density than in temperature.
The Influence of spot size on the expansion dynamics of nanosecond-laser-produced copper plasmas in atmosphere
Authors: Li Xingwen , Wei Wenfu , Wu Jian , Jia Shenli , Qiu Aici
Published: June 2013

Laser produced copper plasmas of different spot sizes in air were investigated using fast photography and optical emission spectroscopy (OES). The laser energy was 33 mJ. There were dramatic changes in the plasma plume expansion into the ambient air when spot sizes changed from ∼0.1 mm to ∼0.6 mm. A stream-like structure and a hemispherical structure were, respectively, observed. It appeared that the same spot size resulted in similar expansion dynamics no matter whether the target was located in the front of or behind the focal point, although laser-induced air breakdown sometimes occurred in the latter case. Plasma plume front positions agree well with the classic blast wave model for the large spot-size cases, while an unexpected stagnation of ∼80 ns occurred after the laser pulse ends for the small spot size cases. This stagnation can be understood in terms of the evolution of enhanced plasma shielding effects near the plasma front. Axial distributions of plasma components by OES revealed a good confinement effect. Electron number densities were estimated and interpreted using the recorded Intensified Charge Coupled Device (ICCD) images.