bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and properties of a meso- tris–ferrocene appended zinc(ii) porphyrin and a critical evaluation of its dye sensitised solar cell (DSSC) performance
Authors: Sirbu D. , Turta C. , Benniston A. C. , Abou-Chahine F. , Lemmetyinen H. , Tkachenko N. V. , Wood C. , Gibson E.
Published: May 2014

A zinc(ii) porphyrin derivative, F3P, was prepared containing a single ferrocene group appended at three of the meso positions.
Fe3O4@chitosan nanoparticles: a valuable heterogeneous nanocatalyst for the synthesis of 2,4,5-trisubstituted imidazoles
Authors: Zarnegar Zohre , Safari Javad
Published: May 2014

Chitosan-coated Fe3O4 nanoparticles (Fe3O4@CS) were prepared simply through in situ co-precipitation of Fe2+ and Fe3+ ions via NH4OH in an aqueous solution of chitosan and their catalytic activity was investigated in the synthesis of 2,4,5-trisubstituted imidazoles by a one-pot condensation of benzil derivatives, aryl aldehydes and ammonium acetate in EtOH.
Zn(ii) promoted dramatic enhancement in the enantioselective fluorescent recognition of functional chiral amines by a chiral aldehyde
Authors: Huang Zeng , Yu Shanshan , Wen Kaili , Yu Xiaoqi , Pu Lin
Published: May 2014

The addition of Zn2+ to the methanol solution of a BINOL-based chiral dialdehyde leads to dramatically enhanced enantioselective fluorescent responses toward various functional chiral amines, representing one of the first chiral aldehydes capable of such recognition.
Structure determined charge transport in single DNA molecule break junctions
Authors: Wang Kun , Hamill Joseph M. , Wang Bin , Guo Cunlan , Jiang Sibo , Huang Zhen , Xu Bingqian
Published: May 2014

Single DNA conductance measurements with increasing MgCl2concentrations unambiguously revealed two DNA (B and Z) conformations and the B–Z transition process.
The role of the hydrophobic phase in the unique rheological properties of saponin adsorption layers
Authors: Golemanov Konstantin , Tcholakova Slavka , Denkov Nikolai , Pelan Eddie , Stoyanov Simeon D.
Published: May 2014

Non-spherical emulsion droplets (centre) may appear at high interfacial elasticity which, however, depends on the type of oil used.
Destruction of cancer cells by laser-induced shock waves: recent developments in experimental treatments and multiscale computer simulations
Authors: Steinhauser Martin Oliver , Schmidt Mischa
Published: May 2014

In this emerging area article we review recent experimental and computational progress in the exploration of the mechanical destruction of cancer cells using laser-induced shock waves.
Thiolated human serum albumin cross-linked dextran hydrogels as a macroscale delivery system
Authors: Gao Yue , Kieltyka Roxanne E. , Jesse Wim , Norder Ben , Korobko Alexander V. , Kros Alexander
Published: May 2014

A biohybrid hydrogel system using human serum albumin as a simultaneous drug carrier and covalent cross-linker was established for macroscale drug delivery.
Casein kinase: the triple meaning of a misnomer
Authors: Venerando Andrea , Ruzzene Maria , Pinna Lorenzo A.
Published: May 2014

The term ‘casein kinase’ has been widely used for decades to denote protein kinases sharing the ability to readily phosphorylate casein in vitro. These fall into three main classes: two of them, later renamed as protein kinases CK1 (casein kinase 1, also known as CKI) and CK2 (also known as CKII), are pleiotropic members of the kinome functionally unrelated to casein, whereas G-CK, or genuine casein kinase, responsible for the phosphorylation of casein in the Golgi apparatus of the lactating mammary gland, has only been identified recently with Fam20C [family with sequence similarity 20C; also known as DMP-4 (dentin matrix protein-4)], a member of the four-jointed family of atypical protein kinases, being responsible for the phosphorylation of many secreted proteins. In hindsight, therefore, the term ‘casein kinase’ is misleading in every instance; in the case of CK1 and CK2, it is because casein is not a physiological substrate, and in the case of G-CK/Fam20C/DMP-4, it is because casein is just one out of a plethora of its targets, and a rather marginal one at that. Strikingly, casein kinases altogether, albeit representing a minimal proportion of the whole kinome, appear to be responsible for the generation of up to 40–50% of non-redundant phosphosites currently retrieved in human phosphopeptides database. In the present review, a short historical explanation will be provided accounting for the usage of the same misnomer to denote three unrelated classes of protein kinases, together with an update of our current knowledge of these pleiotropic enzymes, sharing the same misnomer while playing very distinct biological roles.
Death-associated protein kinase 3 mediates vascular structural remodelling via stimulating smooth muscle cell proliferation and migration
Authors: Usui Tatsuya , Sakatsume Tomoki , Nijima Ryo , Otani Kosuke , Kazama Kyosuke , Morita Tomoka , Kameshima Satoshi , Okada Muneyoshi , Yamawaki Hideyuki
Published: May 2014

Death-associated protein kinase 3 (DAPK3) also known as zipper-interacting kinase is a serine/threonine kinase that mainly regulates cell death and smooth muscle contraction. We have previously found that protein expression of DAPK3 increases in the mesenteric artery from spontaneously hypertensive rats (SHRs) and that DAPK3 mediates the development of hypertension in SHRs partly through promoting reactive oxygen species-dependent vascular inflammation. However, it remains to be clarified how DAPK3 controls smooth muscle cell (SMC) proliferation and migration, which are also important processes for hypertension development. We, therefore, sought to investigate whether DAPK3 affects SMC proliferation and migration. siRNA against DAPK3 significantly inhibited platelet-derived growth factor (PDGF)-BB-induced SMC proliferation and migration as determined by bromodeoxyuridine (BrdU) incorporation and a cell counting assay as well as a Boyden chamber assay respectively. DAPK3 siRNA or a pharmacological inhibitor of DAPK3 inhibited PDGF-BB-induced lamellipodia formation as determined by rhodamine–phalloidin staining. DAPK3 siRNA or the DAPK inhibitor significantly reduced PDGF-BB-induced activation of p38 and heat-shock protein 27 (HSP27) as determined by Western blotting. In ex vivo studies, PDGF-BB-induced SMC out-growth was significantly inhibited by the DAPK inhibitor. In vivo, the DAPK inhibitor significantly prevented carotid neointimal hyperplasia in a mouse ligation model. The present results, for the first time, revealed that DAPK3 mediates PDGF-BB-induced SMC proliferation and migration through activation of p38/HSP27 signals, which may lead to vascular structural remodelling including neointimal hyperplasia. The present study suggests DAPK3 as a novel pharmaceutical target for the prevention of hypertensive cardiovascular diseases.
Targeting mitochondrial 18 kDa translocator protein (TSPO) regulates macrophage cholesterol efflux and lipid phenotype
Authors: Taylor Janice M. W. , Allen Anne-Marie , Graham Annette
Published: May 2014

The aim of the present study was to establish mitochondrial cholesterol trafficking 18 kDa translocator protein (TSPO) as a potential therapeutic target, capable of increasing macrophage cholesterol efflux to (apo)lipoprotein acceptors. Expression and activity of TSPO in human (THP-1) macrophages were manipulated genetically and by the use of selective TSPO ligands. Cellular responses were analysed by quantitative PCR (Q-PCR), immunoblotting and radiolabelling, including [3H]cholesterol efflux to (apo)lipoprotein A-I (apoA-I), high-density lipoprotein (HDL) and human serum. Induction of macrophage cholesterol deposition by acetylated low-density lipoprotein (AcLDL) increased expression of TSPO mRNA and protein, reflecting findings in human carotid atherosclerosis. Transient overexpression of TSPO enhanced efflux (E%) of [3H]cholesterol to apoA-I, HDL and human serum compared with empty vector (EV) controls, whereas gene knockdown of TSPO achieved the converse. Ligation of TSPO (using PK11195, FGIN-1-27 and flunitrazepam) triggered increases in [3H]cholesterol efflux, an effect that was amplified in TSPO-overexpressing macrophages. Overexpression of TSPO induced the expression of genes [PPARA (peroxisome-proliferator-activated receptor α), NR1H3 (nuclear receptor 1H3/liver X receptor α), ABCA1 (ATP-binding cassette A1), ABCG4 (ATP-binding cassette G4) and APOE (apolipoprotein E)] and proteins (ABCA1 and PPARα) involved in cholesterol efflux, reduced macrophage neutral lipid mass and lipogenesis and limited cholesterol esterification following exposure to AcLDL. Thus, targeting TSPO reduces macrophage lipid content and prevents macrophage foam cell formation, via enhanced cholesterol efflux to (apo)lipoprotein acceptors.
Green optical orthogonal frequency‐division multiplexing networks
Authors: El‐Gorashi Taisir E.H. , Dong Xiaowen , Elmirghani Jaafar M.H.
Published: May 2014

Orthogonal frequency‐division multiplexing (OFDM) has been proposed as an enabling technique for elastic optical networks to support heterogeneous traffic demands by enabling rate and modulation adaptive bandwidth allocation. The authors investigate the energy efficiency of optical OFDM‐based networks. A mixed integer linear programming model is developed to minimise the total power consumption of rate and modulation adaptive optical OFDM networks. Considering a symmetric traffic, the results show that optical OFDM‐based networks can save up to 31% of the total network power consumption compared to conventional Internet protocol over wavelength division multiplexing (WDM) networks. Considering the power consumption of the optical layer, the optical OFDM‐based network saves up to 55% of the optical layer power consumption. The results also show that under an asymmetric traffic scenario, where more traffic is destined to or originates from popular nodes, for example data centres, the power savings achieved by the optical OFDM‐based networks are limited as the higher traffic demands to and from data centres reduce the bandwidth wastage associated with conventional WDM networks. Furthermore, the achievable power savings through data compression have been investigated, considering an optical OFDM‐based network.
The impact of Hall physics on magnetized high energy density plasma jets
Authors: Gourdain P.-A. , Seyler C. E. , Atoyan L. , Greenly J. B. , Hammer D. A. , Kusse B. R. , Pikuz S. A. , Potter W. M. , Schrafel P. C. , Shelkovenko T. A.
Published: May 2014

Hall physics is often neglected in high energy density plasma jets due to the relatively high electron density of such jets (ne ∼ 1019 cm−3). However, the vacuum region surrounding the jet has much lower densities and is dominated by Hall electric field. This electric field redirects plasma flows towards or away from the axis, depending on the radial current direction. A resulting change in the jet density has been observed experimentally. Furthermore, if an axial field is applied on the jet, the Hall effect is enhanced and ignoring it leads to serious discrepancies between experimental results and numerical simulations. By combining high currents (∼1 MA) and magnetic field helicity (15° angle) in a pulsed power generator such as COBRA, plasma jets can be magnetized with a 10 T axial field. The resulting field enhances the impact of the Hall effect by altering the density profile of current-free plasma jets and the stability of current-carrying plasma jets (e.g., Z-pinches).
Dynamics in a tetrahedral network glassformer: Vibrations, network rearrangements, and diffusion
Authors: Kawasaki Takeshi , Kim Kang , Onuki Akira
Published: May 2014

We perform molecular dynamics simulation on a tetrahedral network glassformer using a model for viscous SiO2 by Coslovich and Pastore [J. Phys.: Condens. Matter 21, 285107 (2009)]. In this system, Si and O particles form a random network at low temperature T. We attach an ellipsoid to each particle to represent its time-averaged vibration tensor. We then examine the anisotropic vibrations of Si and O, where the ellipsoid orientations are correlated with the network. The ellipsoids exhibit marked vibrational heterogeneity. The configuration changes occur as breakage and reorganization of the network, where only one or two particles undergo large jumps at each rearrangement leading to diffusion. To the time-correlation functions, however, the particles surrounding these largely displaced ones yield significantly T-dependent contributions, resulting in a weak violation of the Stokes-Einstein relation. This crossover is mild in silica due to the small Si–O bond numbers per particle, while it is strong in fragile glassformers with large coordination numbers. On long timescales, jump events tend to occur in the same regions forming marked dynamic heterogeneity. We also calculate the diffusion constants and the viscosity. The diffusion obeys activation dynamics and may be studied by short-time analysis of irreversible jumps.
Effect of quantum nuclear motion on hydrogen bonding
Authors: McKenzie Ross H. , Bekker Christiaan , Athokpam Bijyalaxmi , Ramesh Sai G.
Published: May 2014

This work considers how the properties of hydrogen bonded complexes, X–H⋯Y, are modified by the quantum motion of the shared proton. Using a simple two-diabatic state model Hamiltonian, the analysis of the symmetric case, where the donor (X) and acceptor (Y) have the same proton affinity, is carried out. For quantitative comparisons, a parametrization specific to the O–H⋯O complexes is used. The vibrational energy levels of the one-dimensional ground state adiabatic potential of the model are used to make quantitative comparisons with a vast body of condensed phase data, spanning a donor-acceptor separation (R) range of about 2.4 − 3.0 Å, i.e., from strong to weak hydrogen bonds. The position of the proton (which determines the X–H bond length) and its longitudinal vibrational frequency, along with the isotope effects in both are described quantitatively. An analysis of the secondary geometric isotope effect, using a simple extension of the two-state model, yields an improved agreement of the predicted variation with R of frequency isotope effects. The role of bending modes is also considered: their quantum effects compete with those of the stretching mode for weak to moderate H-bond strengths. In spite of the economy in the parametrization of the model used, it offers key insights into the defining features of H-bonds, and semi-quantitatively captures several trends.
General model of phospholipid bilayers in fluid phase within the single chain mean field theory
Authors: Guo Yachong , Pogodin Sergey , Baulin Vladimir A.
Published: May 2014

Coarse-grained model for saturated phospholipids: 1,2-didecanoyl-sn-glycero-3-phosphocholine (DCPC), 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC), 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) and unsaturated phospholipids: 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), 1,2- dioleoyl-sn-glycero-3-phosphocholine (DOPC) is introduced within the single chain mean field theory. A single set of parameters adjusted for DMPC bilayers gives an adequate description of equilibrium and mechanical properties of a range of saturated lipid molecules that differ only in length of their hydrophobic tails and unsaturated (POPC, DOPC) phospholipids which have double bonds in the tails. A double bond is modeled with a fixed angle of 120°, while the rest of the parameters are kept the same as saturated lipids. The thickness of the bilayer and its hydrophobic core, the compressibility, and the equilibrium area per lipid correspond to experimentally measured values for each lipid, changing linearly with the length of the tail. The model for unsaturated phospholipids also fetches main thermodynamical properties of the bilayers. This model is used for an accurate estimation of the free energies of the compressed or stretched bilayers in stacks or multilayers and gives reasonable estimates for free energies. The proposed model may further be used for studies of mixtures of lipids, small molecule inclusions, interactions of bilayers with embedded proteins.
Order of wetting transitions in electrolyte solutions
Authors: Ibagon Ingrid , Bier Markus , Dietrich S.
Published: May 2014

For wetting films in dilute electrolyte solutions close to charged walls we present analytic expressions for their effective interface potentials. The analysis of these expressions renders the conditions under which corresponding wetting transitions can be first- or second-order. Within mean field theory we consider two models, one with short- and one with long-ranged solvent-solvent and solvent-wall interactions. The analytic results reveal in a transparent way that wetting transitions in electrolyte solutions, which occur far away from their critical point (i.e., the bulk correlation length is less than half of the Debye length) are always first-order if the solvent-solvent and solvent-wall interactions are short-ranged. In contrast, wetting transitions close to the bulk critical point of the solvent (i.e., the bulk correlation length is larger than the Debye length) exhibit the same wetting behavior as the pure, i.e., salt-free, solvent. If the salt-free solvent is governed by long-ranged solvent-solvent as well as long-ranged solvent-wall interactions and exhibits critical wetting, adding salt can cause the occurrence of an ion-induced first-order thin-thick transition which precedes the subsequent continuous wetting as for the salt-free solvent.
An efficient algorithm for multipole energies and derivatives based on spherical harmonics and extensions to particle mesh Ewald
Authors: Simmonett Andrew C. , Pickard Frank C. , Schaefer Henry F. , Brooks Bernard R.
Published: May 2014

Next-generation molecular force fields deliver accurate descriptions of non-covalent interactions by employing more elaborate functional forms than their predecessors. Much work has been dedicated to improving the description of the electrostatic potential (ESP) generated by these force fields. A common approach to improving the ESP is by augmenting the point charges on each center with higher-order multipole moments. The resulting anisotropy greatly improves the directionality of the non-covalent bonding, with a concomitant increase in computational cost. In this work, we develop an efficient strategy for enumerating multipole interactions, by casting an efficient spherical harmonic based approach within a particle mesh Ewald (PME) framework. Although the derivation involves lengthy algebra, the final expressions are relatively compact, yielding an approach that can efficiently handle both finite and periodic systems without imposing any approximations beyond PME. Forces and torques are readily obtained, making our method well suited to modern molecular dynamics simulations.
The Lorenz energy cycle in simulated rotating annulus flows
Authors: Young R. M. B.
Published: May 2014

Lorenz energy cycles are presented for a series of simulated differentially heated rotating annulus flows, in the axisymmetric, steady, amplitude vacillating, and structurally vacillating flow regimes. The simulation allows contributions to the energy diagnostics to be identified in parts of the fluid that cannot be measured in experiments. These energy diagnostics are compared with laboratory experiments studying amplitude vacillation, and agree well with experimental time series of kinetic and potential energy, as well as conversions between them. Two of the three major energy transfer paradigms of the Lorenz energy cycle are identified—a Hadley-cell overturning circulation, and baroclinic instability. The third, barotropic instability, was never dominant, but increased in strength as rotation rate increased. For structurally vacillating flow, which matches the Earth's thermal Rossby number well, the ratio between energy conversions associated with baroclinic and barotropic instabilities was similar to the measured ratio in the Earth's mid-latitudes.
Jitter characteristic of series magnetic pulse compressor employed in ns trigger generator
Authors: Lin Jiajin , Zhang Jiande , Yang Jianhua , Zhang Huibo , Qiu Yongfeng , Yang Xiao
Published: May 2014

The jitter characteristic of series magnetic pulse compressor (MPC) employed in ns trigger generator was explored. The time delay of the series MPC is the sum value of the compression time in each stage. The primary voltage disturbance is the original parameter to affect the timing stability of the system. Decreasing the relative jitter of the primary voltage and the first compression time are the practical and exclusive approaches to decrease to time jitter of the series MPC. The jitter experiment was carried out on the three-stage series MPC charged with a fast step-up LC transformer. The performance data show that the delay time decreases with the increase of primary voltage. Meanwhile, the measured ratio between the time jitter and the relative jitter of the primary voltage accords with the theoretical result.
Magnetoelectric force microscopy based on magnetic force microscopy with modulated electric field
Authors: Geng Yanan , Wu Weida
Published: May 2014

We present the realization of a mesoscopic imaging technique, namely, the Magnetoelectric Force Microscopy (MeFM), for visualization of local magnetoelectric effect. The basic principle of MeFM is the lock-in detection of local magnetoelectric response, i.e., the electric field-induced magnetization, using magnetic force microscopy. We demonstrate MeFM capability by visualizing magnetoelectric domains on single crystals of multiferroic hexagonal manganites. Results of several control experiments exclude artifacts or extrinsic origins of the MeFM signal. The parameters are tuned to optimize the signal to noise ratio.
Bulk ion acceleration and particle heating during magnetic reconnection in a laboratory plasma
Authors: Yoo Jongsoo , Yamada Masaaki , Ji Hantao , Jara-Almonte Jonathan , Myers Clayton E.
Published: May 2014

Bulk ion acceleration and particle heating during magnetic reconnection are studied in the collisionless plasma of the Magnetic Reconnection Experiment (MRX). The plasma is in the two-fluid regime, where the motion of the ions is decoupled from that of the electrons within the ion diffusion region. The reconnection process studied here is quasi-symmetric since plasma parameters such as the magnitude of the reconnecting magnetic field, the plasma density, and temperature are compatible on each side of the current sheet. Our experimental data show that the in-plane (Hall) electric field plays a key role in ion heating and acceleration. The electrostatic potential that produces the in-plane electric field is established by electrons that are accelerated near the electron diffusion region. The in-plane profile of this electrostatic potential shows a “well” structure along the direction normal to the reconnection current sheet. This well becomes deeper and wider downstream as its boundary expands along the separatrices where the in-plane electric field is strongest. Since the in-plane electric field is 3–4 times larger than the out-of-plane reconnection electric field, it is the primary source of energy for the unmagnetized ions. With regard to ion acceleration, the Hall electric field causes ions near separatrices to be ballistically accelerated toward the outflow direction. Ion heating occurs as the accelerated ions travel into the high pressure downstream region. This downstream ion heating cannot be explained by classical, unmagnetized transport theory; instead, we conclude that ions are heated by re-magnetization of ions in the reconnection exhaust and collisions. Two-dimensional (2-D) simulations with the global geometry similar to MRX demonstrate downstream ion thermalization by the above mechanisms. Electrons are also significantly heated during reconnection. The electron temperature sharply increases across the separatrices and peaks just outside of the electron diffusion region. Unlike ions, electrons acquire energy mostly from the reconnection electric field, and the energy gain is localized near the X-point. However, the increase in the electron bulk flow energy remains negligible. These observations support the assertion that efficient electron heating mechanisms exist around the electron diffusion region and that the heat generated there is quickly transported along the magnetic field due to the high parallel thermal conductivity of electrons. Classical Ohmic dissipation based on the perpendicular Spitzer resistivity is too small to balance the measured heat flux, indicating the presence of anomalous electron heating.
Perturbation of nuclear spin polarizations in solid state NMR of nitroxide-doped samples by magic-angle spinning without microwaves
Authors: Thurber Kent R. , Tycko Robert
Published: May 2014

We report solid state 13C and 1H nuclear magnetic resonance (NMR) experiments with magic-angle spinning (MAS) on frozen solutions containing nitroxide-based paramagnetic dopants that indicate significant perturbations of nuclear spin polarizations without microwave irradiation. At temperatures near 25 K, 1H and cross-polarized 13C NMR signals from 15N,13C-labeled L-alanine in trinitroxide-doped glycerol/water are reduced by factors as large as six compared to signals from samples without nitroxide doping. Without MAS or at temperatures near 100 K, differences between signals with and without nitroxide doping are much smaller. We attribute most of the reduction of NMR signals under MAS near 25 K to nuclear spin depolarization through the cross-effect dynamic nuclear polarization mechanism, in which three-spin flips drive nuclear polarizations toward equilibrium with spin polarization differences between electron pairs. When T1e is sufficiently long relative to the MAS rotation period, the distribution of electron spin polarization across the nitroxide electron paramagnetic resonance lineshape can be very different from the corresponding distribution in a static sample at thermal equilibrium, leading to the observed effects. We describe three-spin and 3000-spin calculations that qualitatively reproduce the experimental observations.
Surface wave dynamics in orbital shaken cylindrical containers
Authors: Reclari M. , Dreyer M. , Tissot S. , Obreschkow D. , Wurm F. M. , Farhat M.
Published: May 2014

Be it to aerate a glass of wine before tasting, to accelerate a chemical reaction, or to cultivate cells in suspension, the “swirling” (or orbital shaking) of a container ensures good mixing and gas exchange in an efficient and simple way. Despite being used in a large range of applications this intuitive motion is far from being understood and presents a richness of patterns and behaviors which has not yet been reported. The present research charts the evolution of the waves with the operating parameters identifying a large variety of patterns, ranging from single and multiple crested waves to breaking waves. Free surface and velocity fields measurements are compared to a potential sloshing model, highlighting the existence of various flow regimes. Our research assesses the importance of the modal response of the shaken liquids, laying the foundations for a rigorous mixing optimization of the orbital agitation in its applications.
High-efficiency rare cell identification on a high-density self-assembled cell arrangement chip
Authors: Chen Tsung-Ju , Wu Jen-Kuei , Chang Yu-Cheng , Fu Chien-Yu , Wang Tsung-Pao , Lin Chun-Yen , Chang Hwan-You , Chieng Ching-Chang , Tzeng Chung-Yuh , Tseng Fan-Gang
Published: May 2014

Detection of individual target cells among a large amount of blood cells is a major challenge in clinical diagnosis and laboratory protocols. Many researches show that two dimensional cells array technology can be incorporated into routine laboratory procedures for continuously and quantitatively measuring the dynamic behaviours of large number of living cells in parallel, while allowing other manipulations such as staining, rinsing, and even retrieval of targeted cells. In this study, we present a high-density cell self-assembly technology capable of quickly spreading over 300 000 cells to form a dense mono- to triple-layer cell arrangement in 5 min with minimal stacking of cells by the gentle incorporation of gravity and peripheral micro flow. With this self-assembled cell arrangement (SACA) chip technology, common fluorescent microscopy and immunofluorescence can be utilized for detecting and analyzing target cells after immuno-staining. Validated by experiments with real human peripheral blood samples, the SACA chip is suitable for detecting rare cells in blood samples with a ratio lower than 1/100 000. The identified cells can be isolated and further cultured in-situ on a chip for follow-on research and analysis. Furthermore, this technology does not require external mechanical devices, such as pump and valves, which simplifies operation and reduces system complexity and cost. The SACA chip offers a high-efficient, economical, yet simple scheme for identification and analysis of rare cells. Therefore, potentially SACA chip may provide a feasible and economical platform for rare cell detection in the clinic.
Optical induction scheme for assembling nondiffracting aperiodic Vogel spirals
Authors: Diebel Falko , Rose Patrick , Boguslawski Martin , Denz Cornelia
Published: May 2014

We introduce an experimental approach to realize aperiodic photonic lattices based on multiplexing of nondiffracting Bessel beams. This holographic optical induction scheme takes advantage of the well localized Bessel beam as a basis to assemble two-dimensional photonic lattices. We present the realization of an optically induced two-dimensional golden-angle Vogel spiral lattice, which belongs to the family of deterministic aperiodic structures. With our technique, a very broad class of photonic refractive index landscapes now becomes accessible to optical induction, which could not be realized with established distributed holographic techniques.
Numerical simulations of output pulse extraction from a high-power microwave compressor with a plasma switch
Authors: Shlapakovski Anatoli , Beilin Leonid , Bliokh Yuri , Donskoy Moshe , Hadas Yoav , Schamiloglu Edl , Krasik Yakov E.
Published: May 2014

Numerical simulations of the process of electromagnetic energy release from a high-power microwave pulse compressor comprising a gas-filled cavity and interference switch were carried out. A microwave plasma discharge in a rectangular waveguide H-plane tee was modeled with the use of the fully electromagnetic particle-in-cell code MAGIC. The gas ionization, plasma evolution, and interaction with RF fields accumulated within the compressor were simulated using different approaches provided by the MAGIC code: particle-in-cell approach accounting for electron-neutral collisions, gas conductivity model based on the concept of mobility, and hybrid modeling. The dependences of the microwave output pulse peak power and waveform on parameters that can be controlled in experiments, such as an external ionization rate, RF field amplitude, and background gas pressure, were investigated.
Broad compositional tunability of indium tin oxide nanowires grown by the vapor-liquid-solid mechanism
Authors: Zervos M. , Mihailescu C. N. , Giapintzakis J. , Luculescu C. R. , Florini N. , Komninou Ph. , Kioseoglou J. , Othonos A.
Published: May 2014

Indium tin oxide nanowires were grown by the reaction of In and Sn with O2 at 800 °C via the vapor-liquid-solid mechanism on 1 nm Au/Si(001). We obtain Sn doped In2O3 nanowires having a cubic bixbyite crystal structure by using In:Sn source weight ratios > 1:9 while below this we observe the emergence of tetragonal rutile SnO2 and suppression of In2O3 permitting compositional and structural tuning from SnO2 to In2O3 which is accompanied by a blue shift of the photoluminescence spectrum and increase in carrier lifetime attributed to a higher crystal quality and Fermi level position.
Electromechanical response of multilayer piezoelectric actuators for fuel injectors at high temperatures
Authors: Narita Fumio , Hasegawa Ryohei , Shindo Yasuhide
Published: May 2014

This paper studies the electromechanical response of multilayer piezoelectric actuators from room to high temperatures for fuel injector applications. A phenomenological model of depolarization at high temperatures was proposed, and the temperature dependent piezoelectric coefficients were obtained. The nonlinear electromechanical fields of the multilayer piezoelectric actuators due to the depolarization at high temperatures were then calculated by the finite element method. In addition, experimental results on the electric field induced strain at high temperatures were presented to validate the predictions.
Simulated study of plasmonic coupling in noble bimetallic alloy nanosphere arrays
Authors: Bansal Amit , Verma S. S.
Published: May 2014

The plasmonic coupling between the interacting noble metal nanoparticles plays an important role to influence the optical properties of arrays. In this work, we have extended the Mie theory results of our recent communication to include the effect of particle interactions between the alloy nanoparticles by varying interparticle distance and number of particles. The localized surface plasmon resonance (LSPR) peak position, full width at half maxima (FWHM) and scattering efficiency of one dimensional (1D) bimetallic alloy nanosphere (BANS) arrays of earlier optimized compositions i.e. Ag0.75Au0.25, Au0.25Cu0.75 and Ag0.50Cu0.50 have been studied presently by using discrete dipole approximation (DDA) simulations. Studies have been made to optimize size of the nanosphere, number of spheres in the arrays, material and the interparticle distance. It has been found that both the scattering efficiency and FWHM (bandwidth) can be controlled in the large region of the electromagnetic (EM) spectrum by varying the number of interacting particles and interparticle distance. In comparison to other alloy arrays, Ag0.50Cu0.50 BANS arrays (each of particle radius 50 nm) shows larger tunability of LSPR with wide bandwidth (essential condition for plasmonic solar cells).
Unit-cell thick BaTiO3 blocks octahedral tilt propagation across oxide heterointerface
Authors: Kan Daisuke , Aso Ryotaro , Kurata Hiroki , Shimakawa Yuichi
Published: May 2014

We fabricated SrRuO3/BaTiO3/GdScO3 heterostructures in which the BaTiO3 layer is one unit cell thick by pulsed laser deposition and elucidated how the BaTiO3 layer influences structural and magneto-transport properties of the SrRuO3 layer through octahedral connections across the heterointerface. Our X-ray-diffraction-based structural characterizations show that while an epitaxial SrRuO3 layer grown directly on a GdScO3 substrate is in the monoclinic phase with RuO6 octahedral tilts, a one-unit-cell-thick BaTiO3 layer inserted between SrRuO3 and GdScO3 stabilizes the tetragonal SrRuO3 layer with largely reduced RuO6 tilts. Our high-angle annular dark-field and annular bright-field scanning transmission electron microscopy observations provide an atomic-level view of the octahedral connections across the heterostructure and reveal that the BaTiO3 layer only one unit cell thick is thick enough to stabilize the RuO6-TiO6 octahedral connections with negligible in-plane oxygen atomic displacements. This results in no octahedral tilts propagating into the SrRuO3 layer and leads to the formation of a tetragonal SrRuO3 layer. The magneto-transport property characterizations also reveal a strong impact of the octahedral connections modified by the inserted BaTiO3 layer on the spin-orbit interaction of the SrRuO3 layer. The SrRuO3 layer on BaTiO3/ GdScO3 has in-plane magnetic anisotropy. This is in contrast to the magnetic anisotropy of the monoclinic SrRuO3 films on the GdScO3 substrate, in which the easy axis is ∼45° to the film surface normal. Our results demonstrate that the one-unit-cell-thick layer of BaTiO3 can control and manipulate the interfacial octahedral connection closely linked to the structure-property relationship of heterostructures.
Annealing influence on the Gilbert damping parameter and the exchange constant of CoFeB thin films
Authors: Conca A. , Papaioannou E. Th. , Klingler S. , Greser J. , Sebastian T. , Leven B. , Lösch J. , Hillebrands B.
Published: May 2014

We present a study of the influence of the annealing temperature Ta on the magnetic properties of Co40Fe40B20 thin films. Using a vector network analyzer ferromagnetic resonance (VNA-FMR) setup and the magneto-optical Kerr effect, the dependence of the Gilbert damping parameter α, the exchange constant A, the saturation magnetization as well as the coercive field and the Kerr signal on Ta is reported. Additionally, the correlation with the crystalline properties of the films studied by X-ray diffractometry is discussed. We found that while the damping parameter α and the coercive field show sharp changes starting at a certain Ta value, the exchange constant A and the Kerr signal show a steady evolution. A differential modification of the film surface compared to the bulk is discussed as a possible reason. In any case, we found that the low damping values are preserved at the first onset of crystallization.
Influence of substrate heating on hole geometry and spatter area in femtosecond laser drilling of silicon
Authors: Jiao L. S. , Moon S. K. , Ng E. Y. K. , Zheng H. Y. , Son H. S.
Published: May 2014

The objective of this research is to evaluate the effects of the hole geometry and the spatter area around the drilled hole by femtosecond laser deep drilling on silicon with various temperatures. Deep through holes were produced on single crystal silicon wafer femtosecond laser at elevated temperatures ranging from 300 K to 873 K in a step of 100 K. The laser drilling efficiency is increased by 56% when the temperature is elevated from 300 K to 873 K. The spatter area is found to continuously decrease with increasing substrate temperature. The reason for such changes is discussed based on the enhanced laser energy absorption at the elevated temperature.
Polarization imaging in ferroelectric polymer thin film capacitors by pyroelectric scanning microscopy
Authors: Song Jingfeng , Lu Haidong , Gruverman Alexei , Ducharme S.
Published: May 2014

A Pyroelectric Scanning Microscopy system, which uses laser-induced thermal modulation for mapping the pyroelectric response, has been used to image a bipolar domain pattern in a ferroelectric polymer thin film capacitor. This system has achieved a resolution of 660 ± 28 nm by using a violet laser and high f-number microscope objective to reduce the optical spot size, and by operating at high modulation frequencies to reduce the thermal diffusion length. The results agree well with a thermal model implemented numerically using finite element analysis.
Instability of crystal/melt interface including twin boundaries of silicon
Authors: Fujiwara K. , Tokairin M. , Pan W. , Koizumi H. , Nozawa J. , Uda S.
Published: May 2014

The instability of crystal/melt interfaces including twin boundaries and no twin boundaries of silicon were studied using in situ observation technique. It was found that the instability is promoted at the twin boundaries on the flat crystal/melt interface. We showed that the Mullins and Sekerka theory cannot apply to an interface including twin boundaries, while it can apply to an interface including no twin boundaries. It was shown that the instability occurs even in a positive temperature gradient and the wavelength of the perturbation is determined by the twin spacing in the case of an interface including twin boundaries.
Using interlayer step-wise triplet transfer to achieve an efficient white organic light-emitting diode with high color-stability
Authors: Wang Qi , Ma Dongge , Leo Karl , Ding Junqiao , Wang Lixiang , Qiao Qiquan , Jia Huiping , Gnade Bruce E.
Published: May 2014

An efficient phosphorescent white organic light emitting-diode with a red-green-blue tri-emitting-layer structure is reported. The host of the red dopant possesses a lower triplet-energy than the green dye. An interlayer step-wise triplet transfer via blue dye → green dye → red host → red dye is achieved. This mechanism allows an efficient triplet harvesting by the three dopants, thus maintaining a balanced white light and reducing energy loss. Moreover, the color stability of the device is improved significantly. The white device not only achieves a peak external quantum efficiency of 21.1 ± 0.8% and power efficiency of 37.5 ± 1.4 lm/W but shows no color shift over a wide range of voltages.
Spin force and the generation of sustained spin current in time-dependent Rashba and Dresselhaus systems
Authors: Ho Cong Son , Jalil Mansoor B. A. , Tan Seng Ghee
Published: May 2014

The generation of spin current and spin polarization in a two-dimensional electron gas structure is studied in the presence of Dresselhaus and Rashba spin-orbit couplings (SOC), the strength of the latter being modulated in time by an ac gate voltage. By means of the non-Abelian gauge field approach, we established the relation between the Lorentz spin force and the spin current in the SOC system, and showed that the longitudinal component of the spin force induces a transverse spin current. For a constant (time-invariant) Rashba system, we recover the universal spin Hall conductivity of e8π, derived previously via the Berry phase and semi-classical methods. In the case of a time-dependent SOC system, the spin current is sustained even under strong impurity scattering. We evaluated the ac spin current generated by a time-modulated Rashba SOC in the absence of any dc electric field. The magnitude of the spin current reaches a maximum when the modulation frequency matches the Larmor frequency of the electrons.
Eutectic structures in friction spot welding joint of aluminum alloy to copper
Authors: Shen Junjun , Suhuddin Uceu F. H. , Cardillo Maria E. B. , dos Santos Jorge F.
Published: May 2014

A dissimilar joint of AA5083 Al alloy and copper was produced by friction spot welding. The Al-MgCuAl2 eutectic in both coupled and divorced manners were found in the weld. At a relatively high temperature, mass transport of Cu due to plastic deformation, material flow, and atomic diffusion, combined with the alloy system of AA5083 are responsible for the ternary eutectic melting.
A bisected pupil for studying single-molecule orientational dynamics and its application to three-dimensional super-resolution microscopy
Authors: Backer Adam S. , Backlund Mikael P. , von Diezmann Lexy , Sahl Steffen J. , Moerner W. E.
Published: May 2014

A phase mask design that we term a “bisected pupil” (BSP) provides several advantages for single-molecule optical imaging. When using the BSP with a dual-polarization optical Fourier processing system, both the position and dipole orientation of individual fluorescent molecules may be measured from a single camera image. In the context of single-molecule super-resolution microscopy, this technique permits one to diagnose, and subsequently to remove imaging artifacts resulting from orientation-induced localization errors. If the molecules labeling a structure are rotationally mobile, thus mitigating dipole orientation errors, this technique enables super-resolution imaging in three dimensions. We present simulations and experimental verification.
Exciton storage in type-II quantum dots using the optical Aharonov-Bohm effect
Authors: Climente Juan I. , Planelles Josep
Published: May 2014

We investigate the bright-to-dark exciton conversion efficiency in type-II quantum dots subject to a perpendicular magnetic field. To this end, we take the exciton storage protocol recently proposed by Simonin and co-workers [Phys. Rev. B 89, 075304 (2014)] and simulate its coherent dynamics. We confirm the storage is efficient in perfectly circular structures subject to weak external electric fields, where adiabatic evolution is dominant. In practice, however, the efficiency rapidly degrades with symmetry lowering. Besides, the use of excited states is likely unfeasible owing to the fast decay rates. We then propose an adaptation of the protocol which does not suffer from these limitations.
Singlet fission efficiency in tetracene-based organic solar cells
Authors: Wu Tony C. , Thompson Nicholas J. , Congreve Daniel N. , Hontz Eric , Yost Shane R. , Van Voorhis Troy , Baldo Marc A.
Published: May 2014

Singlet exciton fission splits one singlet exciton into two triplet excitons. Using a joint analysis of photocurrent and fluorescence modulation under a magnetic field, we determine that the triplet yield within optimized tetracene organic photovoltaic devices is 153% ± 5% for a tetracene film thickness of 20 nm. The corresponding internal quantum efficiency is 127% ± 18%. These results are used to prove the effectiveness of a simplified triplet yield measurement that relies only on the magnetic field modulation of fluorescence. Despite its relatively slow rate of singlet fission, the measured triplet yields confirm that tetracene is presently the best candidate for use with silicon solar cells.
Cherenkov radiation oscillator without reflectors
Authors: Li D. , Wang Y. , Hangyo M. , Wei Y. , Yang Z. , Miyamoto S.
Published: May 2014

This Letter presents a Cherenkov radiation oscillator with an electron beam travelling over a finitely thick plate made of negative-index materials. In such a scheme, the external reflectors required in the traditional Cherenkov oscillators are not necessary, since the electromagnetic energy flows backward in the negative-index materials, leading to inherent feedback. We theoretically analyzed the interaction between the electron beam and the electromagnetic wave, and worked out the growth rate and start current through numerical calculations. With the help of particle-in-cell simulation, the theoretical predictions are well demonstrated.
Enantioselective Pd-Catalysed Deallylative γ-Lactonisation of Propargyl Carbazolone Allyl Carbonates: Mechanistic Insight into their Decarboxylative Allylation
Authors: Simpson Quillon , Konrath Robert , Lupton David W.
Published: May 2014

Subjection of N-methyl carbazolone allyl carbonates bearing a propargyl side chain to Pd0 catalysis leads to the formation of enantioenriched γ-lactones, rather than the expected products of decarboxylative allylation. This side reaction has not been observed with the enantioselective decarboxylative allylation of related β-ketoesters, and provides evidence for a mechanism involving turnover limiting decarboxylation from the palladium carboxylate resting state. Following lactonisation, the Pd0 catalyst is regenerated by PdII reductive alkyne coupling.
Can arable forage production be intensified sustainably? A case study from northern Germany
Authors: Herrmann Antje , Claus Sandra , Loges Ralf , Kluß Christof , Taube Friedhelm
Published: May 2014

Greenhouse gas emissions (GHG) resulting from forage production contribute a major share to ‘livestock’s long shadow’. A 2-year field experiment was conducted at two sites in northern Germany to quantify and evaluate the carbon footprint of arable forage cropping systems (continuous silage maize, maize–wheat–grass rotation, perennial ryegrass ley) as affected by N-fertiliser type and N amount. Total GHG emissions showed a linear increase with N application, with mineral-N supply resulting in a steeper slope. Product carbon footprint (PCF) ranged between –66 and 119 kg CO2eq/(GJ net energy lactation) and revealed a quadratic or linear response to fertiliser N input, depending on the cropping system and site. Thus, exploitation of yield potential while mitigating PCF was not feasible for all tested cropping systems. When taking credits or debts for carbon sequestration into account, perennial ryegrass was characterised by a lower PCF than continuous maize or the maize-based rotation, at the N input required for achieving maximum energy yield, whereas similar or higher PCF was found when grassland was assumed to have achieved soil carbon equilibrium. The data indicate potential for sustainable intensification when cropping systems and crop management are adapted to increase resource-use efficiency.