bluuebunny/crossref_metadata_2025 huggingface dataset:
The Occupancy of the Components in the Cervical Spine and Their Changes with Extension and Flexion
Authors: Sayıt Emrah , Aghdasi Bayan , Daubs Michael D. , Wang Jeffrey C.
Published: May 2015

Study Design

Retrospective case series.

Objectives

The kinematics of the cervical spine has been investigated by many researchers. However, the occupancy of the disk bulges, spinal cord, ligamentum flavum, and the rest of the canal as well as the changes of these structures with motion have not yet been investigated. The goal of this study is to investigate these dynamic changes.

Methods

The kinetic magnetic resonance images of 248 patients (124 men and 124 women) were evaluated, and the occupancy of each structure for each cervical level at neutral, flexion, and extension were calculated.

Results

Whole canal anteroposterior (AP) diameters showed significant differences between neutral-extension and flexion-extension at the C4–C5 and C5–C6 levels ( p < 0.05). The mean disk bulges showed significant differences between neutral-flexion and flexion-extension at the C4–C5, C5–C6, C6–C7, and C7–T1 levels ( p < 0.01). The mean spinal canal AP diameter showed significant differences between flexion-extension and neutral-extension at the C3–C4, C4–C5, C5–C6, and C6–C7 levels ( p < 0.05). There were significant differences between neutral-flexion at the C4–C5, C5–C6, and C6–C7 levels ( p < 0.05). The mean thickness of the ligamentum flavum showed significant differences between flexion-extension at the C3–C4, C4–C5, C5–C6, and C6–C7 levels ( p < 0.001). There were significant differences between neutral-extension at the C3–C4 and C5–C6 levels ( p < 0.05). There were significant differences between neutral-flexion at the C5–C6 and C6–C7 levels ( p < 0.05). The mean thickness of the spinal cord showed significant differences between neutral-flexion at the C2–C3 and C3–C4 levels ( p < 0.05). There were significant differences between flexion-extension at the C3–C4 and C4–C5 levels ( p < 0.01). The rest of the canal showed significant differences between neutral-extension and flexion-extension at the C3–C4, C4–C5, C5–C6, and C6–C7 levels ( p < 0.005). There were significant differences between neutral-flexion at the C5–C6 and C6–C7 levels ( p < 0.01).

Conclusions

The occupancy of each structure in the cervical spine for each level was revealed by this study. In addition, the dynamic changes in the cervical spine with flexion and extension were seen to have different characteristics for each level.
Rubber friction on road surfaces: Experiment and theory for low sliding speeds
Authors: Lorenz B. , Oh Y. R. , Nam S. K. , Jeon S. H. , Persson B. N. J.
Published: May 2015

We study rubber friction for tire tread compounds on asphalt road surfaces. The road surface topographies are measured using a stylus instrument and atomic force microscopy, and the surface roughness power spectra are calculated. The rubber viscoelastic modulus mastercurves are obtained from dynamic mechanical analysis measurements and the large-strain effective modulus is obtained from strain sweep data. The rubber friction is measured at different temperatures and sliding velocities, and is compared to the calculated data obtained using the Persson contact mechanics theory. We conclude that in addition to the viscoelastic deformations of the rubber surface by the road asperities, there is an important contribution to the rubber friction from shear processes in the area of contact. The analysis shows that the latter contribution may arise from rubber molecules (or patches of rubber) undergoing bonding-stretching-debonding cycles as discussed in a classic paper by Schallamach.
In-line silicon Schottky photodetectors on silicon cored fibers working in 1550 nm wavelength regimes
Authors: Huang Yen Po , Wang Lon A.
Published: May 2015

We demonstrate an in-line silicon Schottky Photodetector (SSPD) operating at telecom wavelengths based on internal photoemission process. Instead of using silicon waveguides obtained by conventional semiconductor process, a silicon cored fiber was used for making the SSPD. The inherent waveguide property of Si-cored fiber enabled the SSPD to be connected directly with a receiving silica fiber, eliminating the need of aerial optical coupling. The SSPD exhibited comparable photo-detection characteristics such as responsivity when compared to the conventional SSPDs in 1550 nm.
Integrable equations and recursion operators related to the affine Lie algebras Ar(1)
Authors: Gerdjikov V. S. , Mladenov D. M. , Stefanov A. A. , Varbev S. K.
Published: May 2015

We have derived a family of equations related to the untwisted affine Lie algebras Ar(1) using a Coxeter ℤr+1 reduction. They represent the third member of the hierarchy of soliton equations related to the algebra. Applying additional ℤ2-involutions, we also obtain the real Hamiltonian forms of these equations. We also give some particular examples and impose additional reductions.
Protein mediated membrane adhesion
Authors: Carlson Andreas , Mahadevan L.
Published: May 2015

Adhesion in the context of mechanical attachment, signaling, and movement in cellular dynamics is mediated by the kinetic interactions between membrane-embedded proteins in an aqueous environment. Here, we present a minimal theoretical framework for the dynamics of membrane adhesion that accounts for the kinetics of protein binding, the elastic deformation of the membrane, and the hydrodynamics of squeeze flow in the membrane gap. We analyze the resulting equations using scaling estimates to characterize the spatiotemporal features of the adhesive patterning and corroborate them using numerical simulations. In addition to characterizing aspects of cellular dynamics, our results might also be applicable to a range of phenomena in physical chemistry and materials science where flow, deformation, and kinetics are coupled to each other in slender geometries.
Mechanical stability of piezoelectric properties in ferroelectric perovskites
Authors: Schader Florian H. , Morozov Maxim , Wefring Espen T. , Grande Tor , Webber Kyle G.
Published: May 2015

The influence of uniaxial compressive stress on the small signal direct piezoelectric coefficient of hard and soft Pb(Zr,Ti)O3 at the morphotropic phase boundary was investigated as a function of temperature from 25 °C to 450 °C. The stress- and temperature-dependent piezoelectric data indicate that stress is capable of either directly or indirectly modifying the orientation of polar defects in the crystal lattice and reduce the internal bias field. At higher temperatures, the mobility of polar defects was found to increase, corresponding to a two-step decrease in the direct piezoelectric coefficient and a decrease in the frequency dispersion. Quenching experiments were used to elucidate the role of the internal bias field on the stress-dependent piezoelectric response.
Performance analysis of a digital capacitance measuring circuit
Authors: Xu Lijun , Sun Shijie , Cao Zhang , Yang Wuqiang
Published: May 2015

This paper presents the design and study of a digital capacitance measuring circuit with theoretical analysis, numerical simulation, and experimental evaluation. The static and dynamic performances of the capacitance measuring circuit are first defined, including signal-to-noise ratio (SNR), standard deviation, accuracy, linearity, sensitivity, and response time, within a given measurement range. Then numerical simulation is carried out to analyze the SNR and standard deviation of the circuit, followed by experiments to validate the overall performance of the circuit. The simulation results show that when the standard deviation of noise is 0.08 mV and the measured capacitance decreases from 6 pF to 3 fF, the SNR decreases from 90 dB to 22 dB and the standard deviation is between 0.17 fF and 0.24 fF. The experimental results show that when the measured capacitance decreases from 6 pF to 40 fF and the data sampled in a single period are used for demodulation, the SNR decreases from 88 dB to 40 dB and the standard deviation is between 0.18 fF and 0.25 fF. The maximum absolute error and relative error are 5.12 fF and 1.26%, respectively. The SNR and standard deviation can be further improved if the data sampled in more than one period are used for demodulation by the circuit.
Interfaces and internal layers in a turbulent boundary layer
Authors: Eisma Jerke , Westerweel Jerry , Ooms Gijs , Elsinga Gerrit E.
Published: May 2015

New experimental research is presented on the characteristics of interfaces and internal shear layers that are present in a turbulent boundary layer (TBL). The turbulent/non-turbulent (T/NT) interface at the outer boundary of the TBL shows the presence of a finite jump in streamwise velocity and is characterised by a thin shear layer. It appears that similar layers of high shear occur also within the TBL which separate regions of almost uniform momentum. It turns out that they exhibit similar characteristics as the external T/NT interface. Furthermore, the spatial growth rate of the TBL, that is derived from theoretical analysis, can be correctly predicted from a momentum balance near the external T/NT interface. Similarly, the entrainment velocities for the average internal layers have been determined. Results indicate that internal layers move slower in the vicinity of the wall, whereas they move faster than the large scale boundary layer growth rate in the outer region of the TBL. It is believed that shear layers bound large scale flow regions of approximately uniform momentum. Hence, the entrainment velocities of these internal layers may be interpreted as growth rates of the large scale motions in a TBL.
Density functional theory study of the influence of segregation of S or Fe impurities on electromigration in nano-grained copper interconnects
Authors: Shabalin M. , Fuks D.
Published: May 2015

The reliability of the circuits in the modern microelectronic devices remains, during last decades, one of the key topics in research and gains an attention for improving the promising candidates for conductors. Improvement of materials for such applications can be obtained by both electronic and compositional optimization. Ab initio calculations using full potential linearized augmented plane wave method in density functional theory are applied to explain the reduction in electromigration effect in the vicinity of grain boundaries (GB) in nano-structured Cu due to the segregation of some additives to the GB. Several possible mechanisms are considered. It is demonstrated that S atoms segregated to GB of nano-structured Cu lead to the growth of effective mass of the electrons. This decreases the mobility of electrons in external electric field, and, correspondingly, the momentum that they may transfer to atoms in collisions. Fe atoms segregated to GB of Cu create new empty states at the top of the valance band. These non-occupied states may stimulate the current of holes when external electric field is applied to the system, creating the “hole wind” in the direction opposite to the current of electrons. Such “hole wind” will compensate the forces generated by the electron current and therefore will reduce the total momentum transfer between charge carriers and atoms. The calculated electron density maps show that S and Fe segregating to Cu GB increases the strength of covalent bonds reducing the diffusion of Cu atoms in the vicinity of GB.
Negative vortices: The formation of vortex rings with reversed rotation in viscoelastic liquids
Authors: Palacios-Morales Carlos , Barbosa Christophe , Solorio Francisco , Zenit Roberto
Published: May 2015

The formation process of vortex rings in a viscoelastic liquid is studied experimentally considering a piston-cylinder arrangement. Initially, a vortex ring begins to form as fluid is injected from the cylinder into the tank in a manner similar to that observed for Newtonian liquids. For later times, when the piston ceases its motion, the flow changes dramatically. A secondary vortex with reversed spinning direction appears and grows to be as large in size as the original one. The formation process is studied by contrasting the evolution with that obtained for Newtonian liquids with equivalent Reynolds numbers and stroke ratios. We argue that the reversing flow, or negative vortex, results from the combined action of shear and extension rates produced during the vortex formation, in a process similar to that observed behind ascending bubbles and falling spheres in viscoelastic media.
Effects of magnetization on fusion product trapping and secondary neutron spectra
Authors: Knapp P. F. , Schmit P. F. , Hansen S. B. , Gomez M. R. , Hahn K. D. , Sinars D. B. , Peterson K. J. , Slutz S. A. , Sefkow A. B. , Awe T. J. , Harding E. , Jennings C. A. , Desjarlais M. P. , Chandler G. A. , Cooper G. W. , Cuneo M. E. , Geissel M. , Harvey-Thompson A. J. , Porter J. L. , Rochau G. A. , Rovang D. C. , Ruiz C. L. , Savage M. E. , Smith I. C. , Stygar W. A. , Herrmann M. C.
Published: May 2015

By magnetizing the fusion fuel in inertial confinement fusion (ICF) systems, the required stagnation pressure and density can be relaxed dramatically. This happens because the magnetic field insulates the hot fuel from the cold pusher and traps the charged fusion burn products. This trapping allows the burn products to deposit their energy in the fuel, facilitating plasma self-heating. Here, we report on a comprehensive theory of this trapping in a cylindrical DD plasma magnetized with a purely axial magnetic field. Using this theory, we are able to show that the secondary fusion reactions can be used to infer the magnetic field-radius product, BR, during fusion burn. This parameter, not ρR, is the primary confinement parameter in magnetized ICF. Using this method, we analyze data from recent Magnetized Liner Inertial Fusion experiments conducted on the Z machine at Sandia National Laboratories. We show that in these experiments BR ≈ 0.34(+0.14/−0.06) MG · cm, a ∼ 14× increase in BR from the initial value, and confirming that the DD-fusion tritons are magnetized at stagnation. This is the first experimental verification of charged burn product magnetization facilitated by compression of an initial seed magnetic flux.
Frequency dispersion of the first hyperpolarizabilities of reference molecules for nonlinear optics
Authors: de Wergifosse Marc , Castet Frédéric , Champagne Benoît
Published: May 2015

The frequency dispersion of the hyper-Rayleigh scattering first hyperpolarizabilities (βHRS) of five reference molecules for nonlinear optics, namely, carbon tetrachloride, chloroform, dichloromethane, acetonitrile, and trichloroacetonitrile, is described using the coupled-cluster singles and doubles quadratic response function (CCSD-QRF) as well as approximate schemes. Comparisons to approximate schemes in which the frequency dispersion is evaluated as either a multiplicative or an additive correction to the static hyperpolarizability yield the following observations: (i) errors of the order of 10% or less are usually encountered when using the multiplicative scheme for photon energies far from the lowest dipole-allowed excitation energies, (ii) spurious cases cannot be excluded as evidenced by carbon tetrachloride where the multiplicative scheme predicts a decrease of βHRS in contradiction to the increase obtained using the CCSD-QRF method, and (iii) the additive scheme is at best as reliable as the multiplicative approximation. The two-state approximation presents the advantage of correcting the wrong behavior of the additive and multiplicative schemes for carbon tetrachloride, but it is not an improved solution for the other compounds, while the question of selecting the appropriate dominant excited state remains unanswered. Finally, a new βxyz value of 18.9 a.u. is proposed for carbon tetrachloride in gas phase at λ = 1064 nm, to be compared with the measured 16.9 ± 1.4 a.u. value due to Shelton.
State diagram of an orthogonal spin transfer spin valve device
Authors: Ye Li , Wolf Georg , Pinna Daniele , Chaves-O'Flynn Gabriel D. , Kent Andrew D.
Published: May 2015

We present the switching characteristics of a spin-transfer device that incorporates a perpendicularly magnetized spin-polarizing layer with an in-plane magnetized free and fixed magnetic layer, known as an orthogonal spin transfer spin valve device. This device shows clear switching between parallel (P) and antiparallel (AP) resistance states and the reverse transition (AP → P) for both current polarities. Further, hysteretic transitions are shown to occur into a state with a resistance intermediate between that of the P and AP states, again for both current polarities. These unusual spin-transfer switching characteristics can be explained within a simple macrospin model that incorporates thermal fluctuations and considers a spin-polarized current that is tilted with respect to the free layer's plane, due to the presence of the spin-transfer torque from the polarizing layer.
MoS2 on an amorphous HfO2 surface: An ab initio investigation
Authors: Scopel W. L. , Miwa R. H. , Schmidt T. M. , Venezuela P.
Published: May 2015

The energetic stability, electronic and structural properties of MoS2 adsorbed on an amorphous a-HfO2 surface (MoS2/HfO2) are examined through ab initio theoretical investigations. Our total energy results indicate that the formation of MoS2/HfO2 is an exothermic process with an adsorption energy of 34 meV/Å2, which means that it is more stable than similar systems like graphene/HfO2 and MoS2/SiO2. There are no chemical bonds at the MoS2-HfO2 interface. Upon formation of MoS2/HfO2, the electronic charge distribution is mostly localized at the interface region with no net charge transfer between the adsorbed MoS2 sheet and –HfO2 surface. However, the MoS2 sheet becomes n-type doped when there are oxygen vacancies in the HfO2 surface. Further investigation of the electronic distribution reveals that there are no electron- and hole-rich regions (electron-hole puddles) on the MoS2 sheet, which makes this system promising for use in high-speed nanoelectronic devices.
Integrated semiconductor twin-microdisk laser under mutually optical injection
Authors: Zou Ling-Xiu , Liu Bo-Wen , Lv Xiao-Meng , Yang Yue-De , Xiao Jin-Long , Huang Yong-Zhen
Published: May 2015

We experimentally study the characteristics of an integrated semiconductor twin-microdisk laser under mutually optical injection through a connected optical waveguide. Based on the lasing spectra, four-wave mixing, injection locking, and period-two oscillation states are observed due to the mutually optical injection by adjusting the injected currents applied to the two microdisks. The enhanced 3 dB bandwidth is realized for the microdisk laser at the injection locking state, and photonic microwave is obtained from the electrode of the microdisk laser under the period-two oscillation state. The plentifully dynamical states similar as semiconductor lasers subject to external optical injection are realized due to strong optical interaction between the two microdisks.
Rough surface electrical contact resistance considering scale dependent properties and quantum effects
Authors: Jackson Robert L. , Crandall Erika R. , Bozack Michael J.
Published: May 2015

The objective of this work is to evaluate the effect of scale dependent mechanical and electrical properties on electrical contact resistance (ECR) between rough surfaces. This work attempts to build on existing ECR models that neglect potentially important quantum- and size-dependent contact and electrical conduction mechanisms present due to the asperity sizes on typical surfaces. The electrical conductance at small scales can quantize or show a stepping trend as the contact area is varied in the range of the free electron Fermi wavelength squared. This work then evaluates if these effects remain important for the interface between rough surfaces, which may include many small scale contacts of varying sizes. The results suggest that these effects may be significant in some cases, while insignificant for others. It depends on the load and the multiscale structure of the surface roughness.
Self-consistent Bloch equation for modeling element-specific demagnetization of magnetic alloys and multilayers
Authors: Jiao Xiankai , Xu Lei , Zhang Shufeng
Published: May 2015

Magnetization dynamics of magnetic alloys and multilayers at high temperatures are studied by solving the self-consistent Bloch equation. Upon a fast rise of the temperature, usually driven by a strong femtosecond laser pulse, the element-specific demagnetization shows rich dynamic characteristics. We find that the demagnetization time scales could differ substantially for each constitutes in the same alloy. We discuss plausible reasons for the experimental results of the laser induced magnetization switching of GdFe ferrimagnetic compounds.
Radiation hardness of three-dimensional polycrystalline diamond detectors
Authors: Lagomarsino Stefano , Bellini Marco , Corsi Chiara , Cindro Vladimir , Kanxheri Keida , Morozzi Arianna , Passeri Daniele , Servoli Leonello , Schmidt Christian J. , Sciortino Silvio
Published: May 2015

The three-dimensional concept in particle detection is based on the fabrication of columnar electrodes perpendicular to the surface of a solid state radiation sensor. It permits to improve the radiation resistance characteristics of a material by lowering the necessary bias voltage and shortening the charge carrier path inside the material. If applied to a long-recognized exceptionally radiation-hard material like diamond, this concept promises to pave the way to the realization of detectors of unprecedented performances. We fabricated conventional and three-dimensional polycrystalline diamond detectors, and tested them before and after neutron damage up to 1.2 ×1016 cm−2, 1 MeV-equivalent neutron fluence. We found that the signal collected by the three-dimensional detectors is up to three times higher than that of the conventional planar ones, at the highest neutron damage ever experimented.
Short range order in elemental liquids of column IV
Authors: Mayo M. , Shor S. , Yahel E. , Makov G.
Published: May 2015

The short range order (SRO) in liquid elements of column IV is analysed within the quasi-crystalline model across a wide range of temperatures. It is found that l-Si, Ge, and Sn are well described with a beta-tin like SRO. In contrast, Pb retains a bcc-like SRO similar to other simple elemental liquids. However, a distinction is found between the SRO in Si and Ge and that in Sn, where the latter has a more rigid structure. This difference persists across the entire temperature range examined but is overcome in Si at pressures above 8 GPa, where the liquid structure evolves towards that of Sn.
Numerical investigation of the heat transfer in cylindrical annulus with a dielectric fluid under microgravity
Authors: Travnikov V. , Crumeyrolle O. , Mutabazi I.
Published: May 2015

Three-dimensional (3D) flow driven by thermal convection in a dielectric liquid confined in the gap between two coaxial cylinders is investigated by direct numerical simulations. The inner surface is warmer than the outer one and a high frequency alternating electric tension is applied to the cylinders. The fluid is therefore subjected to a radial dielectrophoretic force which plays the role of a buoyancy force that can generate a thermal convection. We have performed 3D simulations using periodic boundary conditions. The transition from the base state to convective flow occurs via a supercritical bifurcation and leads to helicoidal stationary vortices. The behavior of the heat transfer by convective flow is investigated for different values of the radius ratio, Prandtl number, and electric Rayleigh number.
Growth and oxidization stability of cubic Zr1−xGdxN solid solution thin films
Authors: Höglund C. , Alling B. , Jensen J. , Hultman L. , Birch J. , Hall-Wilton R.
Published: May 2015

We report Zr1−xGdxN thin films deposited by magnetron sputter deposition. We show a solid solubility of the highly neutron absorbing GdN into ZrN along the whole compositional range, which is in excellent agreement with our recent predictions by first-principles calculations. An oxidization study in air shows that Zr1−xGdxN with x reaching from 1 to close to 0 fully oxidizes, but that the oxidization is slowed down by an increased amount of ZrN or stopped by applying a capping layer of ZrN. The crystalline quality of Zr0.5Gd0.5N films increases with substrate temperatures increasing from 100 °C to 900 °C.
An electrically tunable plenoptic camera using a liquid crystal microlens array
Authors: Lei Yu , Tong Qing , Zhang Xinyu , Sang Hongshi , Ji An , Xie Changsheng
Published: May 2015

Plenoptic cameras generally employ a microlens array positioned between the main lens and the image sensor to capture the three-dimensional target radiation in the visible range. Because the focal length of common refractive or diffractive microlenses is fixed, the depth of field (DOF) is limited so as to restrict their imaging capability. In this paper, we propose a new plenoptic camera using a liquid crystal microlens array (LCMLA) with electrically tunable focal length. The developed LCMLA is fabricated by traditional photolithography and standard microelectronic techniques, and then, its focusing performance is experimentally presented. The fabricated LCMLA is directly integrated with an image sensor to construct a prototyped LCMLA-based plenoptic camera for acquiring raw radiation of targets. Our experiments demonstrate that the focused region of the LCMLA-based plenoptic camera can be shifted efficiently through electrically tuning the LCMLA used, which is equivalent to the extension of the DOF.
System overview and characterization of a high-temperature, high-pressure, entrained-flow, laboratory-scale gasifier
Authors: Kelley Madison A. , Jakulewicz Micah S. , Dreyer Christopher B. , Parker Terence E. , Porter Jason M.
Published: May 2015

The high-temperature, high-pressure, entrained-flow, laboratory-scale gasifier at the Colorado School of Mines, including the primary systems and the supporting subsystems, is presented. The gasifier is capable of operating at temperatures and pressures up to 1650 °C and 40 bar. The heated section of the reactor column has an inner diameter of 50 mm and is 1 m long. Solid organic feedstock (e.g., coal, biomass, and solid waste) is ground into batches with particle sizes ranging from 25 to 90 μm and is delivered to the reactor at feed rates of 2–20 g/min. The maximum useful power output of the syngas is 10 kW, with a nominal power output of 1.2 kW. The initial characterization and demonstration results of the gasifier system with a coal feedstock are also reported.
The detection and subsequent volume optimization of biological nanocrystals
Authors: Luft Joseph R. , Wolfley Jennifer R. , Franks Eleanor Cook , Lauricella Angela M. , Gualtieri Ellen J. , Snell Edward H. , Xiao Rong , Everett John K. , Montelione Gaetano T.
Published: May 2015

Identifying and then optimizing initial crystallization conditions is a prerequisite for macromolecular structure determination by crystallography. Improved technologies enable data collection on crystals that are difficult if not impossible to detect using visible imaging. The application of second-order nonlinear imaging of chiral crystals and ultraviolet two-photon excited fluorescence detection is shown to be applicable in a high-throughput manner to rapidly verify the presence of nanocrystals in crystallization screening conditions. It is noted that the nanocrystals are rarely seen without also producing microcrystals from other chemical conditions. A crystal volume optimization method is described and associated with a phase diagram for crystallization.
Quantum dot-based microfluidic biosensor for cancer detection
Authors: Ghrera Aditya Sharma , Pandey Chandra Mouli , Ali Md. Azahar , Malhotra Bansi Dhar
Published: May 2015

We report results of the studies relating to fabrication of an impedimetric microfluidic–based nucleic acid sensor for quantification of DNA sequences specific to chronic myelogenous leukemia (CML). The sensor chip is prepared by patterning an indium–tin–oxide (ITO) coated glass substrate via wet chemical etching method followed by sealing with polydimethylsiloxane (PDMS) microchannel for fluid control. The fabricated microfluidic chip comprising of a patterned ITO substrate is modified by depositing cadmium selenide quantum dots (QCdSe) via Langmuir–Blodgett technique. Further, the QCdSe surface has been functionalized with specific DNA probe for CML detection. The probe DNA functionalized QCdSe integrated miniaturized system has been used to monitor target complementary DNA concentration by measuring the interfacial charge transfer resistance via hybridization. The presence of complementary DNA in buffer solution significantly results in decreased electro-conductivity of the interface due to presence of a charge barrier for transport of the redox probe ions. The microfluidic DNA biosensor exhibits improved linearity in the concentration range of 10−15 M to 10−11 M.
Trifluoroacetic acid as excipient destabilizes melittin causing the selective aggregation of melittin within the centrin-melittin-trifluoroacetic acid complex
Authors: Pastrana-Rios Belinda , del Valle Sosa Liliana , Santiago Jorge
Published: May 2015

Trifluoroacetic acid (TFA) may be the cause of the bottleneck in high resolution structure determination for protein-peptide complexes. Fragment based drug design often involves the use of synthetic peptides which contain TFA (excipient). Our goal was to explore the effects of this excipient on a model complex: centrin-melittin-TFA. We performed Fourier transform infrared, two-dimensional infrared correlation spectroscopies and spectral simulations to analyze the amide I'/I'* band for the components and the ternary complex. Melittin (MLT) was observed to have increased helicity upon its interaction with centrin, followed by the thermally induced aggregation of MLT within the ternary complex in the TFA presence.
A direct algorithm of one-dimensional optimal system for the group invariant solutions
Authors: Hu Xiaorui , Li Yuqi , Chen Yong
Published: May 2015

A direct and systematic algorithm is proposed to find one-dimensional optimal system for the group invariant solutions, which is attributed to the classification of its corresponding one-dimensional Lie algebra. Since the method is based on different values of all the invariants, the process itself can both guarantee the comprehensiveness and demonstrate the inequivalence of the optimal system, with no further proof. To leave the algorithm clear, we illustrate each stage with a couple of well-known examples: the Korteweg-de Vries equation and the heat equation. Finally, we apply our method to the Novikov equation and use the found optimal system to investigate the corresponding invariant solutions.
Comment on “Shape transition of unstrained flattest single-walled carbon nanotubes under pressure” [J. Appl. Phys. 115, 044512 (2014)]
Authors: Vassilev Vassil M. , Djondjorov Peter A. , Mladenov Ivaïlo M.
Published: May 2015

Recently, Mu et al. [J. Appl. Phys. 115, 044512 (2014)] have developed an analytic approach to describe some special shapes of a single-wall carbon nanotube (SWCNT) under hydrostatic pressure. These authors have found approximate analytic expressions for the parametric equations of the tube cross section profile and its curvature at the convex-to-concave transition pressure using a shell-like 2D continuum model describing the shapes of such nanotubes. In this comment, we provide additional insight into this problem taking into account the exact analytic representation of the shapes that a SWCNT attains when subjected to hydrostatic pressure according to the very same continuum model.
Communication: Relation of centroid molecular dynamics and ring-polymer molecular dynamics to exact quantum dynamics
Authors: Hele Timothy J. H. , Willatt Michael J. , Muolo Andrea , Althorpe Stuart C.
Published: May 2015

We recently obtained a quantum-Boltzmann-conserving classical dynamics by making a single change to the derivation of the “Classical Wigner” approximation. Here, we show that the further approximation of this “Matsubara dynamics” gives rise to two popular heuristic methods for treating quantum Boltzmann time-correlation functions: centroid molecular dynamics (CMD) and ring-polymer molecular dynamics (RPMD). We show that CMD is a mean-field approximation to Matsubara dynamics, obtained by discarding (classical) fluctuations around the centroid, and that RPMD is the result of discarding a term in the Matsubara Liouvillian which shifts the frequencies of these fluctuations. These findings are consistent with previous numerical results and give explicit formulae for the terms that CMD and RPMD leave out.
Magnetic and nonthermal effects on the dispersion properties of ion-cyclotron surface wave in a semi-bounded generalized Lorentzian plasma
Authors: Lee Myoung-Jae , Jung Young-Dae
Published: May 2015

The magnetic field strength and the nonthermal effects on the dispersion properties of ion-cyclotron surface wave propagating along the interface of a semi-bounded Lorentzian plasma and a vacuum are kinetically investigated. The direction of external magnetic field is applied in parallel to the interface. By employing the specular reflection boundary condition, the dispersion relation of the ion-cyclotron surface wave is derived in the long wavelength limit. The result shows that the phase velocity of the ion-cyclotron surface wave decreases with an increase of the strength of magnetic field. It is found that the increase of suprathermal particle population suppresses the phase velocity of the surface wave. In addition, it is found that the wave velocity increases with increasing ion mass in a semi-bounded Lorentzian plasma.
Magnetic phase transitions in Ta/CoFeB/MgO multilayers
Authors: Barsukov I. , Fu Yu , Safranski C. , Chen Y.-J. , Youngblood B. , Gonçalves A. M. , Spasova M. , Farle M. , Katine J. A. , Kuo C. C. , Krivorotov I. N.
Published: May 2015

We study thin films and magnetic tunnel junction nanopillars based on Ta/Co20Fe60B20/MgO multilayers by electrical transport and magnetometry measurements. These measurements suggest that an ultrathin magnetic oxide layer forms at the Co20Fe60B20/MgO interface. At approximately 160 K, the oxide undergoes a phase transition from an insulating antiferromagnet at low temperatures to a conductive weak ferromagnet at high temperatures. This interfacial magnetic oxide is expected to have significant impact on the magnetic properties of CoFeB-based multilayers used in spin torque memories.
Interfacial electronic structure at the CH3NH3PbI3/MoOx interface
Authors: Liu Peng , Liu Xiaoliang , Lyu Lu , Xie Haipeng , Zhang Hong , Niu Dongmei , Huang Han , Bi Cheng , Xiao Zhengguo , Huang Jinsong , Gao Yongli
Published: May 2015

Interfacial electronic properties of the CH3NH3PbI3 (MAPbI3)/MoOx interface are investigated using ultraviolet photoemission spectroscopy and X-ray photoemission spectroscopy. It is found that the pristine MAPbI3 film coated onto the substrate of poly (3,4-ethylenedioxythiophene) poly(styrenesulfonate)/indium tin oxide by two-step method behaves as an n-type semiconductor, with a band gap of ∼1.7 eV and a valence band edge of 1.40 eV below the Fermi energy (EF). With the MoOx deposition of 64 Å upon MAPbI3, the energy levels of MAPbI3 shift toward higher binding energy by 0.25 eV due to electron transfer from MAPbI3 to MoOx. Its conduction band edge is observed to almost pin to the EF, indicating a significant enhancement of conductivity. Meanwhile, the energy levels of MoOx shift toward lower binding energy by ∼0.30 eV, and an interface dipole of 2.13 eV is observed at the interface of MAPbI3/MoOx. Most importantly, the chemical reaction taking place at this interface results in unfavorable interface energy level alignment for hole extraction. A potential barrier of ∼1.36 eV observed for hole transport will impede the hole extraction from MAPbI3 to MoOx. On the other hand, a potential barrier of ∼0.14 eV for electron extraction is too small to efficiently suppress electrons extracted from MAPbI3 to MoOx. Therefore, such an interface is not an ideal choice for hole extraction in organic photovoltaic devices.
Adaptive power smoothing control in grid-connected and islanding modes of hybrid micro-grid energy management
Authors: Ambia Mir Nahidul , Al-Durra Ahmed
Published: May 2015

This paper presents an innovative technique for energy management of hybrid micro-grid system during grid connected and islanding modes by adaptive power smoothing control. In order to perform the adaptive power smoothing control, fuzzy logic control algorithm (FLCA) is incorporated with conventional control scheme of dc-dc buck boost converter of the battery energy storage system. A standard battery energy limiter is considered with the dc-dc buck boost controller as smoothing trip controller which can disable the smoothing operation if the state of charge of battery (SOC) exceeds its limits. A secondary frequency control and grid resynchronization technique for the converter between the AC and DC buses are considered for islanding and grid reconnected operations, respectively, to demonstrate the effectiveness of the adaptive technique in smoothing wind farm output power. The proposed FLCA adjusts its reference automatically during transition from grid mode to islanding mode and vice-versa based on the battery's SOC. Several cases have been tested where it has been verified that the FLCA can efficiently manage the SOC, while performing smoothing operation and maintain energy balance due to its adaptive nature instead of completely disabling the wind power smoothing at some extreme conditions.
The operation mechanism of poly(9,9-dioctylfluorenyl-2,7-diyl) dots in high efficiency polymer solar cells
Authors: Liu Chunyu , He Yeyuan , Zhang Xinyuan , Li Zhiqi , Li Jinfeng , Shen Liang , Zhang Zhihui , Guo Wenbin , Ruan Shengping
Published: May 2015

The highly efficient polymer solar cells were realized by doping poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO) dots into active layer. The dependence of doping amount on devices performance was investigated and a high efficiency of 7.15% was obtained at an optimal concentration, accounting for a 22.4% enhancement. The incorporation of PFO dots (Pdots) is conducted to the improvement of Jsc and fill factor mainly due to the enhancement of light absorption and charge transport property. Pdots blended in active layer provides an interface for charge transfer and enables the formation of percolation pathways for electron transport. The introduction of Pdots was proven an effective way to improve optical and electrical properties of solar cells.
Reexamination of basal plane thermal conductivity of suspended graphene samples measured by electro-thermal micro-bridge methods
Authors: Jo Insun , Pettes Michael T. , Lindsay Lucas , Ou Eric , Weathers Annie , Moore Arden L. , Yao Zhen , Shi Li
Published: May 2015

Thermal transport in suspended graphene samples has been measured in prior works and this work with the use of a suspended electro-thermal micro-bridge method. These measurement results are analyzed here to evaluate and eliminate the errors caused by the extrinsic thermal contact resistance. It is noted that the room-temperature thermal resistance measured in a recent work increases linearly with the suspended length of the single-layer graphene samples synthesized by chemical vapor deposition (CVD), and that such a feature does not reveal the failure of Fourier’s law despite the increase in the reported apparent thermal conductivity with length. The re-analyzed apparent thermal conductivity of a single-layer CVD graphene sample reaches about 1680 ± 180 W m−1 K−1 at room temperature, which is close to the highest value reported for highly oriented pyrolytic graphite. In comparison, the apparent thermal conductivity values measured for two suspended exfoliated bi-layer graphene samples are about 880 ± 60 and 730 ± 60 Wm−1K−1 at room temperature, and approach that of the natural graphite source above room temperature. However, the low-temperature thermal conductivities of these suspended graphene samples are still considerably lower than the graphite values, with the peak thermal conductivities shifted to much higher temperatures. Analysis of the thermal conductivity data reveals that the low temperature behavior is dominated by phonon scattering by polymer residue instead of by the lateral boundary.
Multiple paternity in captive grey nurse sharks (Carcharias taurus): implications for the captive breeding of this critically endangered species
Authors: Townsend Robert , Stow Adam , Asmyhr Maria , Momigliano Paolo
Published: May 2015

The grey nurse shark (Carcharius taurus) is listed as threatened throughout much of its global distribution, and as critically endangered in eastern Australia. Captive breeding programs have thus far been largely unsuccessful and little is known of its mating system in this context. Here we carry out a paternity analysis to determine if the mating system in captivity is characterised by multiple mating, and whether poor offspring survival is associated with a particular male. Tissue samples from grey nurse sharks were collected from three potential sires, the two dams and nine pups housed at Manly SEA LIFE Sanctuary in eastern Australia. Each individual was genotyped at seven microsatellite markers and three cases of multiple paternity were inferred. No paternal link to stillborn (5), or scoliotic (2) pups was indicated. For the first time, we show the natural wild phenomenon of multiple paternity occurring in a captive environment.
Subtraction suppressive hybridisation analysis of differentially expressed genes associated with puberty in the goat hypothalamus
Authors: Cao G. L. , Feng T. , Chu M. X. , Di R. , Zhang Y. L. , Huang D. W. , Liu Q. Y. , Hu W. P. , Wang X. Y.
Published: May 2015

The cost of developing replacement nanny goats could be reduced by decreasing the age at puberty because this way nanny goats could be brought into production at an earlier age. The aim of the present study was to screen genes related to puberty to investigate the molecular mechanisms of puberty. Subtracted cDNA libraries were constructed for hypothalami from juvenile (Group A), pubertal (Group B) and age-matched control pubertal (Group E) Jining grey (JG) and Liaoning cashmere (LC) goats using suppression subtractive hybridisation (SSH). Differentially expressed genes were analysed by bioinformatics methods. There were 203 expressed sequence tags (ESTs) in the subtracted cDNA libraries that were differentially expressed between JG and LC goats at the juvenile stage, 226 that were differentially expressed at puberty and 183 that were differentially expressed in the age-matched control group. The differentially expressed ESTs in each subtracted cDNA library were classified as known gene, known EST and unknown EST according to sequence homology in the GenBank non-redundant (NR) and EST database. According to gene function analysis in the COG (Cluster of Orthologous Groups) database, the known genes were grouped into 10 subdivisions in Group A, into seven subdivisions in Group E and into nine subdivisions in Group B under three categories: cellular processes and signalling, information storage and processing, and metabolism. Pathway analysis in the KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway database of known genes revealed that the three pathways that most differentially expressed genes were involved in were metabolic pathways, Parkinson’s disease and oxidative phosphorylation. Protein interaction analysis of the high homology genes revealed the most dominant network to be structure of ribosome/protein translation, oxidative phosphorylation and carbohydrate metabolism. The results reveal that the onset of puberty is a complex event involving multiple genes in multiple biological processes. The differentially expressed genes include genes related to both neuroendocrine and energy metabolism.
Expression profiles of select genes in cumulus–oocyte complexes from young and aged mares
Authors: Cox Lindsay , Vanderwall Dirk K. , Parkinson Kate C. , Sweat Alexis , Isom S. Clay
Published: May 2015

There is compelling evidence that oocytes from mares >18 years of age have a high incidence of inherent defects that result in early embryonic loss. In women, an age-related decrease in oocyte quality is associated with an increased incidence of aneuploidy and it has recently been determined that the gene expression profile of human oocytes is altered with advancing age. We hypothesised that similar age-related aberrations in gene expression occur in equine oocytes. Therefore, the aim of the present study was to compare gene expression profiles of individual oocytes and cumulus cells from young and aged mares, specifically evaluating genes that have been identified as being differentially expressed with advancing maternal age and/or aneuploidy in human oocytes. Expression of 48 genes was compared between 14 cumulus–oocyte complexes (COCs) from mares aged 3–12 years and 10 COCs from mares ≥18 years of age. Three genes (mitochondrial translational initiation factor 3 (IF3), heat shock transcription factor 5 (HSF5) and Y box binding protein 2 (YBX2)) were differentially expressed in oocytes, with all being more abundant in oocytes from young mares. Three genes (ADP-ribosylation factor-like 6 interacting protein 6 (ARL6IP6), BCL2-associated X protein (BAX) and hypoxia upregulated 1 (HYOU1)) were differentially expressed in cumulus cells, with all being more abundant in aged mares. The results of the present study confirm there are age-related differences in gene expression in equine COCs, which may be associated with the lower quality and decreased developmental competence of oocytes from aged mares.