bluuebunny/crossref_metadata_2025 huggingface dataset:
The Martian Dust Storm of Sol 1742
Authors: Moore Henry J.
Published: December 2012

After nearly five Earth years on Mars, the Mutch Memorial Station (Viking Lander 1) finally witnessed a local dust storm that eroded trenches, conical piles, and other disturbed surfaces in the sample field and near the lander. The event, called the Dust Storm of Sol 1742, occurred late in the third winter of lander observations between Sols 1728 and 1757. Analyses of tiny new wind tails and movement of materials indicate that the eroding winds were variable but more northeasterly than those that had previously shaped the surface. Pebbly residues and movement of 4–5 mm clods suggest drag velocities or friction speeds of the winds were about 2.2–4.0 m/s. Wind speeds at the height of the meteorology boom (1.6 m) were probably about 40–50 m/s. Much of the observed erosion could have occurred in a few to several tens of seconds, but somewhat longer times are suggested by analogy with the erosion of terrestrial soils. Most of the erosion occurred where preexisting equilibrium conditions of surface configurations and surface material properties had been altered by the lander during landing and during surface‐sampler activities, but thin layers of bright fine‐grained dust were also removed and redistributed. Surfaces where preexisting equilibrium conditions were unaltered appeared to be uneroded.
Apollo 14 aluminous Mare basalts and their possible relationship to KREEP
Authors: Dickinson T. , Taylor G. J. , Keil K. , Schmitt R. A. , Hughes S. S. , Smith M. R.
Published: December 2012

Thirty‐six aluminous mare basalt fragments from breccia 14321 and other Apollo 14 basalts are statistically divided into two broad groups, comprising five subgroups, using La, Sm, and Yb data. Major element compositions, petrographic characteristics, and mineral compositions are similar for the five groups. However, there is an eight‐fold increase in REE abundances from Group 5 to Group 1, with Group 1 having a REE pattern similar to KREEP. Groups 1 to 3 may be related by partial melting of a source similar to that proposed by Unruh et al. (1984) for feldspathic basalt 12038. However, Groups 4 and 5 cannot be as closely matched by larger degrees of partial melting of this source. Groups 1 to 4 could also be produced by assimilation of a KREEP component by a magma similar in composition to Group 5. Such a magma can be produced by partial melting of an olivine‐orthopyroxene source that crystallized from a magma with chondritic relative REE abundances.
The effects of vacuum ultraviolet radiation on low-k dielectric films
Authors: Sinha H. , Ren H. , Nichols M. T. , Lauer J. L. , Tomoyasu M. , Russell N. M. , Jiang G. , Antonelli G. A. , Fuller N. C. , Engelmann S. U. , Lin Q. , Ryan V. , Nishi Y. , Shohet J. L.
Published: December 2012

Plasmas, known to emit high levels of vacuum ultraviolet (VUV) radiation, are used in the semiconductor industry for processing of low-k organosilicate glass (SiCOH) dielectric device structures. VUV irradiation induces photoconduction, photoemission, and photoinjection. These effects generate trapped charges within the dielectric film, which can degrade electrical properties of the dielectric. The amount of charge accumulation in low-k dielectrics depends on factors that affect photoconduction, photoemission, and photoinjection. Changes in the photo and intrinsic conductivities of SiCOH are also ascribed to the changes in the numbers of charged traps generated during VUV irradiation. The dielectric-substrate interface controls charge trapping by affecting photoinjection of charged carriers into the dielectric from the substrate. The number of trapped charges increases with increasing porosity of SiCOH because of charge trapping sites in the nanopores. Modifications to these three parameters, i.e., (1) VUV induced charge generation, (2) dielectric-substrate interface, and (3) porosity of dielectrics, can be used to reduce trapped-charge accumulation during processing of low-κ SiCOH dielectrics. Photons from the plasma are responsible for trapped-charge accumulation within the dielectric, while ions stick primarily to the surface of the dielectrics. In addition, as the dielectric constant was decreased by adding porosity, the defect concentrations increased.
Physical modeling of the electromechanical behavior of polar heterogeneous polymers
Authors: Diguet Gildas , Bogner Agnes , Chenal Jean-Marc , Cavaille Jean-Yves
Published: December 2012

Some polymers exhibit very high electromechanical activity, and there is a lack of physical understanding of the mechanisms at the origin of this behavior. In amorphous or slightly crystalline polymers, piezoelectric effect is negligible and the contributions to electrostriction are quadratic function of the applied electric field. These contributions are extrinsic and intrinsic, namely, (i) the electrostatic pressure resulting from the two electrodes attraction (Maxwell effect) and (ii) dipoles-electric field interactions resulting in a mechanism so-called electrostriction. The later contribution can reach much higher value, i.e., by a factor 1000, than the Maxwell effect in some polyurethanes. On the other hand, dipoles-dipoles interactions are known to play a negligible role in homogeneous media. In this work, it is shown that both heterogeneities of local stiffness and dielectric constants are responsible for this unexpected behavior. Nano-heterogeneities may result from phase separation in block copolymers, or can be introduced by dispersing nanoparticles within a matrix. A theoretical approach based on dipole-electric field gradient is developed and numerical data are compared with experimental data from the literature.
The relaxation behaviour of supersaturated iron in single-crystal silicon at 500 to 750 °C
Authors: Murphy J. D. , Falster R. J.
Published: December 2012

Iron-related defects cause major problems in silicon for both microelectronic devices and photovoltaics. Iron contamination can occur during high temperature processing or, particularly in the case of low-cost photovoltaics, from the feedstock. In many situations, silicon is cooled too rapidly for the establishment of equilibrium, and so the bulk iron concentration exceeds the solubility value. We have investigated the relaxation of supersaturated bulk iron to the equilibrium solubility in single-crystal silicon. Bulk iron concentrations are measured by analysing the change in minority carrier lifetime that occurs when iron-boron pairs are dissociated. High-purity silicon is rubbed with iron and annealed at 750 °C for 24 h. This process creates an iron silicide phase on the rubbed surface and allows the equilibrium solubility of ∼2 × 1012 cm−3 to be established. Samples are then annealed at lower temperatures (500 to 700 °C) for a range of times. The rate of decay in iron concentration depends upon whether a silicide was formed on one side or two sides, with the kinetics in excellent agreement with iron diffusion to one or both surfaces, respectively. Even for the highest supersaturation (∼2000 times the solubility), the pre-existence of a silicide on one surface means there is insufficient driving force for nucleation of a silicide on the other surface. Relaxation experiments were also performed on contaminated samples for which the iron silicide source at the surface was removed after contamination. The iron concentration decays substantially more slowly in these specimens. The kinetics can be explained by relaxation to bulk voids.
Relaxed active space: Fixing tailored-CC with high order coupled cluster. I
Authors: Melnichuk Anna , Bartlett Rodney J.
Published: December 2012

Several single reference (SR-CC) coupled cluster methods are shown to work for traditionally multi-reference (MR) problems such as bond breaking subject to restricted Hartree-Fock (RHF) references. The correlated methods can successfully describe any MR problem with enough higher order clusters: singles and doubles (CCSD), singles, doubles and triples (CCSDT), singles, doubles, triples, and quadruples (CCSDTQ), etc. However, due to the steep increase in the computational cost, it is not practical to do larger systems or to use large basis sets without active space partitioning. In this study, the orbital space is partitioned into an active space subject to an unambiguous statistical criteria to span the MR behavior which defines an extended space to let the active space relax. The rest is considered the external space. The extended space is treated with CCSDT and the external space with CCSD. An automated scheme for determining the extended space is presented and evaluated. We build upon the tailored-CC scheme of Hino et al. and address its main shortcoming of neglecting the coupling between the active space and the rest of the orbital space which results in loss of accuracy as well as a pronounced nonparallelism error (NPE). The automated scheme makes it unnecessary for the user to judge whether a chosen active space is sufficient to correctly solve the problem. We illustrate this method for the hydrogen fluoride and fluorine molecule ground state dissociation potentials using the extended space partitioning methods. Experimental accuracy for the dissociation energy is achieved at a small fraction of the cost of doing a full CCSDT calculation. This approach is easily amendable to higher order clusters which are required for double and triple bond breaking and other strongly multi-reference systems.
High-voltage electric-field-induced growth of aligned “cow-nipple-like” submicro-nano carbon isomeric structure via chemical vapor deposition
Authors: Liao Chengwei , Zhang Yupeng , Pan Chunxu
Published: December 2012

In this study, a novel vertically aligned carbon material, named “cow-nipple-like” submicro-nano carbon isomeric structure, was synthesized by the thermal decomposition of C2H2 in a chemical-vapor deposition system with a high-voltage external electric field. The microstructures were characterized by using scanning electron microscopy, high-resolution transmission electron microscopy, and Raman spectroscopy, respectively. The results revealed that (1) the total height of the carbon isomeric structure was in a rang of 90-250 nm; (2) the carbon isomeric structure consisted of a submicro- or nano-sized hemisphere carbon ball with 30-120 nm in diameter at the bottom and a vertically grown carbon nanotube with 10-40 nm in diameter upon the carbon ball; (3) there was a sudden change in diameter at the junction of the carbon ball and carbon nanotube. In addition, the carbon isomeric structure showed an excellent controllability, that is, the density, height, and diameter could be controlled effectively by adjusting the precursor ferrocene concentration in the catalytic solution and C2H2 ventilation time. A possible growth model was proposed to describe the formation mechanism, and a theoretic calculation was carried out to discuss the effect of high-voltage electric field upon the growth of the carbon isomeric structure.
Temperature dependence of E and E + ΔSO transitions in In0.53Ga0.47BixAs1−x alloys studied by photoreflectance
Authors: Kudrawiec R. , Kopaczek J. , Misiewicz J. , Walukiewicz W. , Petropoulos J. P. , Zhong Y. , Dongmo P. B. , Zide J. M. O.
Published: December 2012

The temperature dependence of the energy gap (E0) and the spin-orbit split (E0+ΔSO) transitions has been studied by photoreflectance for In0.53Ga0.47BixAs1-x layers with 0 < x ≤ 0.044. It has been observed that at 15 K the E0 transition shifts to red and significantly broadens with increasing Bi concentration, while the E0 + ΔSO transition is almost unaffected. The temperature-induced shifts of the E0 and E0 + ΔSO transitions in the temperature range of 15–295 K have been found to be ∼50–60 meV and ∼80–90 meV, respectively, which is very similar to the energy shift in the In0.53Ga0.47As host material over the same temperature range. Obtained results (energies and broadenings of E0 and E0+ΔSO transitions) have been analyzed using the Varshni and Bose-Einstein formulas. The Varshni and Bose-Einstein parameters have been found to be close to the parameters of conventional narrow bandgap III-V semiconductors.
Conductivity enhancement of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) films post-spincasting
Authors: Farah Abdiaziz A. , Rutledge Steven A. , Schaarschmidt Antje , Lai Roger , Freedman Justin P. , Helmy Amr S.
Published: December 2012

Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) thin films on indium tin oxide and glass substrates have been fabricated and subjected to a non-adiabatic annealing process. The films showed subtle changes in their structure and optical properties as well as an increase in conductivity due to the effects of rapid thermal annealing. Through a combination of Raman spectroscopy, X-ray photoelectron spectroscopy and atomic force microscopy studies in conjunction with electrical characterization, and four-point probe measurements, material enrichment of conductive PEDOT domains at the polymer-metal interface have been demonstrated, which well explains the surface conductivity improvement of a thin film of PEDOT:PSS after annealing.
Magnetic vortex echoes
Authors: Garcia F. , Sinnecker J. P. , Novais E. R. P. , Guimarães A. P.
Published: December 2012

The dynamic properties of magnetic vortices have many potential applications in fast magnetic devices. Here we present a micromagnetic study of the motion of magnetic vortices in arrays of 100 nanodisks that have a normal distribution of diameters, as expected in real array systems, e.g., produced by nanolithography. The micromagnetic simulated experiments follow a protocol with an initial preparation and magnetic pulses that enable the control of the magnetic vortices initial positions and circular motion direction. The results show a new effect—the magnetic vortex echo (MVE) that arises from the refocusing of the overall array magnetization. We show, by using arrays with different interdisk separations, that MVE affords a means of characterizing them as regards the homogeneity and intensity of the interaction between its elements, properties that are relevant for device applications. We also show that a simple analytical model, analogous to the one that describes the spin echo in magnetic resonance, can be used to explain most features of the simulated magnetic vortex echo.
Planar defects and heterostructure in diamond structure photonic crystals
Authors: Dai Wei , Wang Hong
Published: December 2012

Three dimensional diamond structure photonic crystals with planar defects and heterostructure fabricated by rapid prototyping and gel casting with alumina were studied. The influence of ordinary planar defect and twinned planar defect on the transmission properties of the electromagnetic wave in the photonic crystals was first investigated. The normalized resonant intensities are 0.5 and 0.58 for ordinary and twinned planar defect photonic crystals (PCs). The resonant intensity of electromagnetic wave in the twinned planar defect PC is stronger than that in the ordinary planar defect PC and the resonant peak width of the twinned planar defect PC is narrower and steeper than that of the ordinary planar defect PC. The resonant peak intensity and frequency of planar defect modes increase firstly and then decrease with the increase of the planar defect sizes. The strongest resonant peak intensity lies at the defect size with 0.5 mm. If the defect size is more than 2.5 mm, the resonant mode will disappear. In the heterostructure PC, which was realized by combining two perfect PCs with different lattice constants of 9 mm and 12 mm, the band gaps of the two different PCs can be united together.
A modified strong-contrast expansion for estimating the effective thermal conductivity of multiphase heterogeneous materials
Authors: Safdari Masoud , Baniassadi Majid , Garmestani Hamid , Al-Haik Marwan S.
Published: December 2012

To evaluate the effective thermal conductivity of a general anisotropic multiphase microstructure, a modified version of statistical strong-contrast expansions is formulated here. The proposed method takes into account the shape, orientation, and distribution of each phase through two-point and three-point correlation functions. By applying a recently developed method, three-point correlation functions are approximated from the two-point correlation functions. Numerically, it is shown that for high contrast constituents, the solution of the third-order strong-contrast expansions is very sensitive to the selection of the reference medium. A technique is proposed to minimize the sensitivity of the solution. To establish the validity of the methods developed, the effective thermal conductivity of a number of isotropic and anisotropic two-phase and three-phase microstructures is evaluated and compared to their corresponding finite element (FE) simulations. Good agreement between the FE simulations and the proposed method predictions in the cases studied confirms its validity. When there are orders of magnitude disparity between the properties of the constituents, the developed method can be applied to better estimate the effective thermal conductivity of the multiphase heterogeneous materials in comparison with previous strong contrast model and other homogeneous methods.
Relativistic effects on nuclear magnetic shieldings of CHnX4−n and CHXYZ (X, Y, Z = H, F, Cl, Br, I)
Authors: Melo Juan I. , Maldonado Alejandro F. , Aucar Gustavo A.
Published: December 2012

Nuclear magnetic shieldings of both carbon and hydrogen atoms of haluro methyl molecules are highly influenced by the substitution of one or more hydrogen by halogen heavy atoms. We applied the linear response elimination of small components, LRESC, formalism to calculate such shieldings and learn whether including only few terms is enough for getting quantitative reproduction of the total shieldings or not. First, we discuss the contribution of all leading relativistic corrections to σ(C), in CHX2I molecular models with X = H, F, and Cl, and show that spin-orbit (SO) effects are the main ones. After adding the SO effects to the non-relativistic (NR) results, we obtain ∼ 97% (93%) of the total LRESC values for σ(C) (σ(H)). The magnitude of SO terms increases when the halogen atom becomes heavier. In this case, such contributions to σ(C) can be extrapolated as a function of Z, the halogen atomic number. Furthermore, when paramagnetic spin-orbit (PSO) contributions are also considered, we obtain results that are within 1% of the total LRESC value. Then we study in detail the main electronic mechanisms involved to contribute C and H shieldings on CHnX4 − n (n = 1, 3), and CHXYZ (X, Y, Z = F, Cl, Br, I) model compounds. The pattern of σ(C) for all series of compounds follows a normal halogen dependence (NHD), though with different rate of increase. A special family of compounds is that of CHF2X for which σnr(C) follows an inverse halogen dependence though the total shielding have a NHD due to the SO contributions. For the series CH3X (X = F, Cl, Br and I), we found that σSO ∼ \documentclass[12pt]{minimal}\begin{document}${\rm Z}_\text{X}^{2.53}$\end{document}ZX2.53. Another important finding of this work is the logarithmic dependence of σSO(C) with the substituent atomic number: ln σSO(C) = \documentclass[12pt]{minimal}\begin{document}${\rm A}_\text{X}$\end{document}AX + \documentclass[12pt]{minimal}\begin{document}${\rm a}_\text{X}$\end{document}aX \documentclass[12pt]{minimal}\begin{document}${\rm Z}_\text{Y}$\end{document}ZY for both family of compounds CH2XY and CHX2Y. We also performed four-component calculations using the spin-free Hamiltonian to obtain SO contributions within a four-component framework.
Classification of 5d warped spaces with cosmological constant
Authors: Bejancu Aurel , Călin Constantin , Farran Hani Reda
Published: December 2012

Let \documentclass[12pt]{minimal}\begin{document}$(\bar{M}, \bar{g})$\end{document}(M¯,g¯) be a 5D warped space defined by the 4D spacetime (M, g) and the warped function A. By using the extrinsic curvature of the horizontal distribution, we obtain the classification of all spaces \documentclass[12pt]{minimal}\begin{document}$(\bar{M}, \bar{g})$\end{document}(M¯,g¯) satisfying Einstein equations \documentclass[12pt]{minimal}\begin{document}$\bar{G} = -\bar{\lambda }\bar{g}$\end{document}G¯=−λ¯g¯. This enables us to describe all the exact solutions for the warped metric \documentclass[12pt]{minimal}\begin{document}$\bar{g}$\end{document}g¯ by means of 4D exact solutions.
Spiral waves with superstructures in a mixed-mode oscillatory medium
Authors: Tang Xiaodong , Gao Qingyu , Gong Shirui , Zhao Yuemin , Epstein Irving R.
Published: December 2012

Diverse spatiotemporal patterns are generated in a three-variable reaction-diffusion model that supports 11 mixed-mode oscillations. Diffusion-induced instability results in spatiotemporal patterns such as amplitude-modulated overtargets (circular super-waves superimposed on spiral waves) and superspirals. The types of superstructure waves are determined by the ratio of diffusion coefficients, which controls the interaction and competition between two local oscillatory modes, one of which is the original homogeneous 11 mixed-mode oscillation, resulting in periodic amplitude modulation in space. Variation of the control parameter can reverse the chirality and radial propagation direction (outward or inward rotation) of a superspiral pattern. These amplitude-modulated patterns may provide insight into mechanisms of pattern development in some living systems.
A scanning tunneling microscope capable of imaging specified micron-scale small samples
Authors: Tao Wei , Cao Yufei , Wang Huafeng , Wang Kaiyou , Lu Qingyou
Published: December 2012

We present a home-built scanning tunneling microscope (STM) which allows us to precisely position the tip on any specified small sample or sample feature of micron scale. The core structure is a stand-alone soft junction mechanical loop (SJML), in which a small piezoelectric tube scanner is mounted on a sliding piece and a “U”-like soft spring strip has its one end fixed to the sliding piece and its opposite end holding the tip pointing to the sample on the scanner. Here, the tip can be precisely aligned to a specified small sample of micron scale by adjusting the position of the spring-clamped sample on the scanner in the field of view of an optical microscope. The aligned SJML can be transferred to a piezoelectric inertial motor for coarse approach, during which the U-spring is pushed towards the sample, causing the tip to approach the pre-aligned small sample. We have successfully approached a hand cut tip that was made from 0.1 mm thin Pt/Ir wire to an isolated individual 32.5 × 32.5 μm2 graphite flake. Good atomic resolution images and high quality tunneling current spectra for that specified tiny flake are obtained in ambient conditions with high repeatability within one month showing high and long term stability of the new STM structure. In addition, frequency spectra of the tunneling current signals do not show outstanding tip mount related resonant frequency (low frequency), which further confirms the stability of the STM structure.
Fast sweep-rate plastic Faraday force magnetometer with simultaneous sample temperature measurement
Authors: Slobinsky D. , Borzi R. A. , Mackenzie A. P. , Grigera S. A.
Published: December 2012

We present a design for a magnetometer capable of operating at temperatures down to 50 mK and magnetic fields up to 15 T with integrated sample temperature measurement. Our design is based on the concept of a Faraday force magnetometer with a load-sensing variable capacitor. A plastic body allows for fast sweep rates and sample temperature measurement, and the possibility of regulating the initial capacitance simplifies the initial bridge balancing. Under moderate gradient fields of ∼1 T/m our prototype performed with a resolution better than 1 × 10−5 emu. The magnetometer can be operated either in a dc mode, or in an oscillatory mode which allows the determination of the magnetic susceptibility. We present measurements on Dy2Ti2O7 and Sr3Ru2O7 as an example of its performance.
A laser-induced repetitive fast neutron source applied for gold activation analysis
Authors: Lee Sungman , Park Sangsoon , Lee Kitae , Cha Hyungki
Published: December 2012

A laser-induced repetitively operated fast neutron source was developed for applications in laser-driven nuclear physics research. The developed neutron source, which has a neutron yield of approximately 4 × 105 n/pulse and can be operated up to a pulse repetition rate of 10 Hz, was applied for a gold activation analysis. Relatively strong delayed gamma spectra of the activated gold were measured at 333 keV and 355 keV, and proved the possibility of the neutron source for activation analyses. In addition, the nuclear reactions responsible for the measured gamma spectra of gold were elucidated by the 14 MeV fast neutrons resulting from the D(t,n)He4 nuclear reaction, for which the required tritium originated from the primary fusion reaction, D(d,p)T3.
Electron correlation and spin-orbit coupling effects in US3 and USe3
Authors: Yang Yu , Yang Wei , Zhang Ping
Published: December 2012

A systematic density functional theory (DFT)+U study is conducted to investigate the electron correlation and spin-orbit coupling (SOC) effects in US3 and USe3. Our calculations reveal that inclusion of the U term is essential to get energy band gaps for them, indicating the strong correlation effects for uranium 5f electrons. Taking consideration of the SOC effect results in small reduction on the electronic band gaps of US3 and USe3, but largely changes the energy band shapes around the Fermi energy. As a result, US3 has a direct band gap while USe3 has an indirect one. Our calculations predict that both US3 and USe3 are antiferromagnetic insulators, in agreement with corresponding experimental results. Based on our DFT+U calculations, we systematically present the ground-state electronic, mechanical, and Raman properties for US3 and USe3.
Applied stress controls the production of nano-twins in coarse-grained metals
Authors: Cao Y. , Wang Y. B. , Liao X. Z. , Kawasaki M. , Ringer S. P. , Langdon T. G. , Zhu Y. T.
Published: December 2012

We present evidence that the level of the applied stress plays a critical role in deformation twinning in face-centred cubic alloys. While conventional cold rolling of a face-centred cubic structure produces a microstructure with a high-density of extended dislocations, increasing the applied stress using high-pressure torsion gives a nano-twinned coarse-grained structure. This suggests the existence of a critical stress for deformation twinning which thereby delineates an approach for the production of nano-twinned microstructures in coarse-grained materials with superior mechanical properties.
Effect of the magnetic domain structure in the ferromagnetic contact on spin accumulation in silicon
Authors: Ando Y. , Yamada S. , Kasahara K. , Sawano K. , Miyao M. , Hamaya K.
Published: December 2012

We show a marked effect of magnetic domain structure in an epitaxial CoFe contact on spin accumulation signals in Si devices detected by three-terminal Hanle effect measurements. Experimental results indicate that magnetic domain structures cause large discrepancies in the estimation of spin lifetime and bias-current dependence of the spin accumulation signal. By introducing the domain walls in CoFe contact, spin accumulation signals are reduced, which is caused by the lateral spin transport in the Si channel. Thus, to understand precisely the physical properties of Si spintronic devices, it is important to take into account the control of magnetic domain structure in the contacts.
High-level theoretical study of the NO dimer and tetramer: Has the tetramer been observed?
Authors: Ivanic Joseph , Schmidt Michael W. , Luke Brian
Published: December 2012

The ground-state properties of (NO)2 and (NO)4 have been investigated using multireference second-order perturbation theory (MRMP2) and include a two-tier extrapolation to the complete basis set (CBS) limit. For the NO dimer the MRMP2(18,14)/CBS predicted structure, binding energy (with respect to 2NO; De = 3.46 kcal/mol), and dipole moment (ue = 0.169 D) are in excellent agreement with experimental measurements (De = 2.8–3.8 kcal/mol; ue = 0.171 D). Additionally, three of four intermolecular anharmonic MRMP2(18,14)/CBS-estimated frequencies (143 cm−1, 238 cm−1, 421 cm−1) are in excellent agreement with recent gas-phase experimental measurements (135 cm−1, 239 cm−1, 429/428 cm−1); however, the predicted value of 151 cm−1 for the out-of-plane torsion (A2) is elevated compared to recent experimental estimates of 97–117 cm−1. Our finding that this infrared-forbidden vibration is also predicted to have an extremely low Raman activity (0.04 Å/amu at the MP2/QZ level of theory) conflicts with Raman measurements of a strong intensity for a low frequency band; however, these studies were performed for low temperature solid and liquid phases. Probing the possibility of the presence of higher order clusters we investigated the stability of (NO)4 and discovered three isomers, each resembling pairs of dimers, that were stable to dissociation to 2(NO)2, with the lowest-energy isomer (Ci structure) having a predicted binding energy almost identical to that of the dimer. Computed vibrational frequencies of the Ci isomer indicate that the 12 highest-frequency modes resemble barely shifted NO dimer-combined bands while the 13th highest-frequency mode at ∼100 cm−1 is exclusive to (NO)4. Moreover, this tetramer-unique vibration is infrared inactive but has a very high predicted Raman activity of some 24 Å/amu. Guided by the theoretical results, we reexamined and reassigned experimental Raman and infrared data going back to 1951 and determined that our best predictions of vibrational frequencies of (NO)2 and (NO)4 are consistent with experimental observations. We thus postulate the existence and observation of (NO)4.
Chemical and structural investigations of the incorporation of metal manganese into ruthenium thin films for use as copper diffusion barrier layers
Authors: McCoy A. P. , Casey P. , Bogan J. , Lozano J. G. , Nellist P. D. , Hughes G.
Published: December 2012

The incorporation of manganese into a 3 nm ruthenium thin-film is presented as a potential mechanism to improve its performance as a copper diffusion barrier. Manganese (∼1 nm) was deposited on an atomic layer deposited Ru film, and the Mn/Ru/SiO2 structure was subsequently thermally annealed. X-ray photoelectron spectroscopy studies reveal the chemical interaction of Mn with the SiO2 substrate to form manganese-silicate (MnSiO3), implying the migration of the metal through the Ru film. Electron energy loss spectroscopy line profile measurements of the intensity of the Mn signal across the Ru film confirm the presence of Mn at the Ru/SiO2 interface.
Plasma instability in the afterglow of electron cyclotron resonance discharge sustained in a mirror trap
Authors: Izotov I. , Mansfeld D. , Skalyga V. , Zorin V. , Grahn T. , Kalvas T. , Koivisto H. , Komppula J. , Peura P. , Tarvainen O. , Toivanen V.
Published: December 2012

The work presented in this article is devoted to time-resolved diagnostics of non-linear effects observed during the afterglow plasma decay of a 14 GHz electron cyclotron resonance ion source operated in pulsed mode. Plasma instabilities that cause perturbations of the extracted ion current during the decay were observed and studied. It is shown that these perturbations are associated with precipitation of high energy electrons along the magnetic field lines and strong bursts of bremsstrahlung emission. The effect of ion source settings on the onset of the observed instabilities was investigated. Based on the experimental data and estimated plasma properties, it is assumed that the instabilities are of cyclotron type. The conclusion is supported by a comparison to other types of plasma devices which exhibit similar characteristics but which operate in a different plasma confinement regime.
Thermodynamic state-dependent structure-based coarse-graining of confined water
Authors: Mashayak S. Y. , Aluru N. R.
Published: December 2012

We develop thermodynamic state-dependent single-site isotropic coarse-grained potentials to predict the structure of water confined inside graphene slit-like channels by two multiscale simulation approaches: the coarse-grained molecular dynamics (CG-MD) and the empirical potential-based quasi-continuum theory (EQT). The structurally-consistent coarse-grained potentials for the CG-MD and EQT are systematically determined from the reference all-atom SPC/E water MD (AA-MD) results. For optimization of the CG-MD potentials, the relative entropy based coarse-graining method is used, and for determination of the EQT potentials, we develop a potential of mean force matching scheme. The optimized coarse-grained potentials are found to be dependent on the thermodynamic state. They are evaluated for their ability to predict the density profile of confined water, and it is found that the results obtained by the CG-MD and EQT simulations are in good agreement with the reference AA-MD results.
Magnetomechanical behavior for assessment of fatigue process in ferromagnetic steel
Authors: Bao S. , Gong S. F.
Published: December 2012

In this work, the change of magnetization as a function of applied stress has been investigated for test specimens of AISI 1018 steel. The various stages of fatigue damage process are characterized by the magnetomechanical measurements recorded by an APS 428D fluxgate magnetometer. Of great significance is the fact that the stress-magnetic field hysteresis loop area changes systematically with the progression of fatigue. The magnetomechanical hysteresis demonstrates conspicuous changes in the initial stage of fatigue loading, then reverts to a relatively stable phase, and finally, drastic variations appear again as the cyclic loadings approach terminal failure. This work demonstrated that it is possible to correlate the progress of fatigue in ferromagnetic steels with the nondestructive evaluation technique of the magnetomechanical effect.
Physical mechanism and numerical simulation of the inception of the lightning upward leader
Authors: Li Qingmin , Lu Xinchang , Shi Wei , Zhang Li , Zou Liang , Lou Jie
Published: December 2012

The upward leader is a key physical process of the leader progression model of lightning shielding. The inception mechanism and criterion of the upward leader need further understanding and clarification. Based on leader discharge theory, this paper proposes the critical electric field intensity of the stable upward leader (CEFISUL) and characterizes it by the valve electric field intensity on the conductor surface, EL, which is the basis of a new inception criterion for the upward leader. Through numerical simulation under various physical conditions, we verified that EL is mainly related to the conductor radius, and data fitting yields the mathematical expression of EL. We further establish a computational model for lightning shielding performance of the transmission lines based on the proposed CEFISUL criterion, which reproduces the shielding failure rate of typical UHV transmission lines. The model-based calculation results agree well with the statistical data from on-site operations, which show the effectiveness and validity of the CEFISUL criterion.
Dynamics of nanoparticle adhesion
Authors: Carrillo Jan-Michael Y. , Dobrynin Andrey V.
Published: December 2012

We performed molecular dynamics simulations and theoretical analysis of nanoparticle pulling off from adhesive substrates. Our theoretical model of nanoparticle detachment is based on the Kramers' solution of the stochastic barrier crossing in effective one-dimensional potential well. The activation energy, ΔE, for nanoparticle detachment first decreases linearly with increasing the magnitude of the applied force, f, then it follows a power law ΔE ∝ (f* − f)3/2 as magnitude of the pulling force f approaches a critical detachment force value, f*. These two different regimes in activation energy dependence on magnitude of the applied force are confirmed by analyzing nanoparticle detachment in effective one-dimensional potential obtained by weighted histogram analysis method. Simulations show that detachment of nanoparticle proceeds through neck formation such that magnitude of the activation energy is determined by balancing surface energy of the neck connecting particle to a substrate with elastic energy of nanoparticle deformation. In this regime the activation energy at zero applied force, ΔE0, for nanoparticle with radius, Rp, shear modulus, G, surface energy, γp, and work of adhesion, W, is a universal function of the dimensionless parameter δ ∝γpW−2/3(GRp)−1/3. Simulation data are described by a scaling function $\Delta E_0 \propto \gamma _p^{5/2} R_p^{1/2} G^{ - 3/2} \delta ^{ - 3.75}$ΔE0∝γp5/2Rp1/2G−3/2δ−3.75. Molecular dynamics simulations of nanoparticle detachment show that the Kramers' approach fails in the vicinity of the critical detachment force f* where activation energy barrier becomes smaller than the thermal energy kBT. In the interval of the pulling forces f > f* nanoparticle detachment becomes a deterministic process.
Size-variable droplet actuation by interdigitated electrowetting electrode
Authors: Chen Jianfeng , Yu Yuhua , Li Jia , Lai Yongjun , Zhou Jia
Published: December 2012

We propose electrowetting on dielectric (EWOD) electrodes to actuate size-variable droplets. By using interdigitated fingers and maximizing them in optimized construction, we can control droplets in different sizes with the same electrode array automatically. We both do the theory calculation and experiment verification to study the electrode with rectangular fingers. It is found that the electrode with triangle fingers can actuate droplets as small as 1/36 of that actuated by conventional square electrode array. It can actuate large droplets more efficiently than rectangular fingers. This work provides an approach to achieve multifunctional EWOD devices in the future.
Analysis of anomalous traps measured by charge pumping technique in HfO2/metal gate n-channel metal-oxide-semiconductor field-effect transistors
Authors: Ho Szu-Han , Chang Ting-Chang , Lu Ying-shin , Lo Wen-Hung , Chen Ching-En , Tsai Jyun-Yu , Chen Hua-Mao , Wu Chi-Wei , Luo Hung-Ping , Liu Guan-Ru , Tseng Tseung-Yuen , Cheng Osbert , Huang Cheng-Tung , Sze Simon M.
Published: December 2012

This letter investigates anomalous traps measured by charge pumping technique in high voltage in HfO2/metal gate n-channel metal-oxide-semiconductor field-effect transistors. N-Vhigh level characteristic curves with different duty ratios indicate that the electron discharge time dominates the value of N for extra traps. By fitting ln (N (tbase level = 2.5μs)-N (tbase level))-Δtbase level at different temperatures and computing the equation t = τ0 exp (αe,SiO2d SiO2 + αe,HfO2d HfO2,trap), results show that these extra traps measured by the charge pumping technique at high voltage can be attributed to high-k bulk shallow traps.
Room temperature direct-bandgap electroluminescence from n-type strain-compensated Ge/SiGe multiple quantum wells
Authors: Liu Zhi , Hu Weixuan , Li Chong , Li Yaming , Xue Chunlai , Li Chuanbo , Zuo Yuhua , Cheng Buwen , Wang Qiming
Published: December 2012

N-type strain-compensated Ge/Si0.15Ge0.85 multiple quantum wells (MQWs) were grown on a Si0.1Ge0.9 virtual substrate using ultrahigh vacuum chemical vapor deposition on a n+-Si(001) substrate. Under low forward bias voltage ranging from 0.6 to 1.2 V, narrow direct-bandgap electroluminescence (EL) peak from MQWs light emitting diode was observed at room temperature. The quantum confinement effect of the direct-bandgap transitions and the temperature dependent EL peak redshift are in good agreement with the calculated results.
Microwave reflection imaging using a magnetic tunnel junction based spintronic microwave sensor
Authors: Fu L. , Cao Z. X. , Hemour S. , Wu K. , Houssameddine D. , Lu W. , Pistorius S. , Gui Y. S. , Hu C.-M.
Published: December 2012

A far-field microwave imaging technique has been developed using a spintronic sensor based on a magnetic tunnel junction (MTJ). Such a sensor can directly rectify a microwave field into a dc voltage signal using the Seebeck effect. Thanks to the high conversion efficiency of the microwave rectification in MTJs, the microwave power sensitivity of the spintronic sensor is on the order of 1–10 mV/mW. This high sensitivity allows the sensor to directly measure the coherent spatial scattered microwave field distribution, which gives it the ability to non-destructively detect hidden objects down to a few wavelengths in size.
First observation of a new zonal-flow cycle state in the H-mode transport barrier of the experimental advanced superconducting Tokamak
Authors: Xu G. S. , Wang H. Q. , Wan B. N. , Guo H. Y. , Naulin V. , Diamond P. H. , Tynan G. R. , Xu M. , Yan N. , Zhang W. , Chang J. F. , Wang L. , Chen R. , Liu S. C. , Ding S. Y. , Shao L. M. , Xiong H. , Zhao H. L.
Published: December 2012

A new turbulence-flow cycle state has been discovered after the formation of a transport barrier in the H-mode plasma edge during a quiescent phase on the EAST superconducting tokamak. Zonal-flow modulation of high-frequency-broadband (0.05–1 MHz) turbulence was observed in the steep-gradient region leading to intermittent transport events across the edge transport barrier. Good confinement (H98y,2 ∼ 1) has been achieved in this state, even with input heating power near the L-H transition threshold. A novel model based on predator-prey interaction between turbulence and zonal flows reproduced this state well.
A visualization of threading dislocations formation and dynamics in mosaic growth of GaN-based light emitting diode epitaxial layers on (0001) sapphire
Authors: Ravadgar P. , Horng R. H. , Ou S. L.
Published: December 2012

A clear visualization of the origin and characteristics of threading dislocations (TDs) of GaN-based light emitting diode epitaxial layers on (0001) sapphire substrates have been carried out. Special experimental set up and chemical etchant along with field emission scanning electron microscopy are employed to study the dynamics of GaN TDs at different growth stages. Cross-sectional transmission electron microscopy analysis visualized the formation of edge TDs is arising from extension of coalescences at boundaries of different tilting-twining nucleation grains “mosaic growth.” Etch pits as representatives of edge TDs are in agreement with previous theoretical models and analyses of TDs core position and characteristics.
Reduced graphene oxide based flexible organic charge trap memory devices
Authors: Rani Adila , Song Ji-Min , Jung Lee Mi , Lee Jang-Sik
Published: December 2012

A nonvolatile organic transistor memory device was developed using layer-by-layer assembly of 3-aminopropyltriethoxysilane (APTES) and solution-processed, reduced graphene oxide (rGO) as the charge trapping layer on flexible substrates. Reduction of graphene oxide and successful adsorption of the rGO on APTES-covered substrates were confirmed. The organic memory devices based on rGO exhibited reliable programmable memory operations, confirmed by program/erase operations, data retention, and endurance properties. These methods can potentially play a significant role in the fabrication of next-generation flexible nonvolatile memory devices based on graphene materials.
Assessing Juvenile Chinook Salmon Behavior and Entrainment Risk near Unscreened Water Diversions: Large Flume Simulations
Authors: Mussen Timothy D. , Cocherell Dennis , Hockett Zachary , Ercan Ali , Bandeh Hossein , Kavvas M. Levent , Cech Joseph J. , Fangue Nann A.
Published: December 2012

Juvenile Chinook Salmon Oncorhynchus tshawytscha from California's Central Valley must pass thousands of unscreened water diversion pipes during their out‐migration to the Pacific Ocean. The number of fish that become entrained into (drawn through) these diversions at different hydraulic and environmental conditions is currently unknown. We tested the ability of juvenile Chinook Salmon to avoid entrainment into a 0.46‐m‐diameter unscreened water diversion pipe while swimming in a large‐river‐simulation flume. Fish swimming experiments were conducted at 0.15, 0.38, and 0.61 m/s sweeping velocities (simulating the river current) with 0.42 and 0.57 m3/s water diversion rates during the day and at 0.15 and 0.61 m/s with a diversion rate of 0.57 m3/s in turbid water and during the night. The number of fish entrained during day experiments ranged from 0.8% (SE, 0.3) to 8.5% (SE, 0.3). The percentage of pipe passage events resulting in fish entrainment nearly doubled at the 0.57 m3/s water diversion rate (1.7%) compared with that at 0.42 m3/s (0.9%). In clear water conditions during the day, more fish became entrained at the higher water diversion rate (0.57 m3/s) and slower sweeping velocity (0.15 m/s), with fish entrainments starting 38.6 cm (SE, 1.6) from the center of the pipe inlet, where fish experienced an increased velocity gradient and a mean resultant velocity of 0.74 m/s. Fish entrainment was strongly influenced by the number of pipe passages per experiment, rather than by swimming orientation or time spent in the flume. More fish were entrained at the faster sweeping velocity (0.61 m/s) in turbid water during the day and at night, indicating that juvenile Chinook Salmon may use nonvisual guidance (e.g., lateral line system) to avoid water diversions in slower currents. These results help to provide a scientific basis for protecting out‐migrating juvenile Chinook Salmon exposed to unscreened water diversions.
Relationships between the Abundance of Pacific Lamprey in the Columbia River and Their Common Hosts in the Marine Environment
Authors: Murauskas Joshua G. , Orlov Alexei M. , Siwicke Kevin A.
Published: December 2012

The returns of Pacific Lamprey Entosphenus tridentatus to the Columbia River over the past decade have declined significantly compared with the peak returns of the 1950s and 1960s, with no quantifiable mechanisms identified. To determine if the abundance of documented host species in the marine environment is related to adult returns of Pacific Lamprey, we examined stock assessment data, commercial fishery statistics, and counts of adult fish at Bonneville Dam between 1997 and 2010. Significant positive correlations were observed between lamprey returns and abundance indices of Pacific Hake Merluccius productus, Walleye Pollock Theragra chalcogramma, Pacific Cod Gadus macrocephalus, Chinook Salmon Oncorhynchus tshawytscha, and Pacific Herring Clupea pallasii throughout the U.S. Pacific Northwest. Commercial landings of these species in Washington and Oregon were also significantly and strongly correlated to lamprey returns, with the exception of Walleye Pollock. Several of these fisheries have demonstrated significant reductions in mean landings since the 1950s and 1960s, and adult lamprey returns have declined proportionally. We further examined large‐scale and regional indices of oceanic productivity as a potential underlying mechanism. Multiple regression techniques indicated that host abundance was the principal factor in predicting lamprey returns, though inclusion of oceanic conditions increased the precision of the model. These results represent the first established relationship to recent trends of Pacific Lamprey returns to the Columbia River and indicate that spawning escapement is primarily a function of conditions experienced during the predatory phase of the life cycle. We hypothesize that Pacific Lamprey abundance in the Columbia River is cyclical in nature, but limited by availability of several host species over a potentially vast geographic range. Biologists and resource managers should reassess the relatively overlooked marine ecology of Pacific Lamprey.