ALBERT

Description: by Lisa Kellman, Amy Myette, Hugo Beltrami Forest harvesting induces a step change in the climatic variables (temperature and moisture), that control carbon dioxide ( CO 2 ) production arising from soil organic matter decomposition within soils. Efforts to examine these vertically complex relationships in situ within soil profiles are lacking. In this study we examined how the climatic controls on CO 2 production change within vertically distinct layers of the soil profile in intact and clearcut forest soils of a humid temperate forest system of Atlantic Canada. We measured mineral soil temperature (0, 5, 10, 20, 50 and 100 cm depth) and moisture (0–15 cm and 30–60 cm depth), along with CO 2 surface efflux and subsurface concentrations (0, 2.5, 5, 10, 20, 35, 50, 75 and 100 cm depth) in 1 m deep soil pits at 4 sites represented by two forest-clearcut pairs over a complete annual cycle. We examined relationships between surface efflux at each site, and soil heat, moisture, and mineral soil CO 2 production. Following clearcut harvesting we observed increases in temperature through depth (1–2°C annually; often in excess of 4°C in summer and spring), alongside increases in soil moisture (30%). We observed a systematic breakdown in the expected exponential relationship between CO 2 production and heat with mineral soil depth, consistent with an increase in the role moisture plays in constraining CO 2 production. These findings should be considered in efforts to model and characterize mineral soil organic matter decomposition in harvested forest soils.

Description: by Peng Yu, Jing Zhang, Shuchun Yu, Zhenzhong Luo, Fuzhou Hua, Linhui Yuan, Zhidong Zhou, Qin Liu, Xiaohong Du, Sisi Chen, Lieliang Zhang, Guohai Xu Background and Purpose Myocardial infarction leads to heart failure. Autophagy is excessively activated in myocardial ischemia/reperfusion (I/R) in rats. The aim of this study is to investigate whether the protection of sevoflurane postconditioning (SPC) in myocardial I/R is through restored impaired autophagic flux. Methods Except for the sham control (SHAM) group, each rat underwent 30 min occlusion of the left anterior descending coronary (LAD) followed by 2 h reperfusion. Cardiac infarction was determined by 2,3,5-triphenyltetrazolium chloride triazole (TTC) staining. Cardiac function was examined by hemodynamics and echocardiography. The activation of autophagy was evaluated by autophagosome accumulation, LC3 conversion and p62 degradation. Potential molecular mechanisms were investigated by immunoblotting, real-time PCR and immunofluorescence staining. Results SPC improved the hemodynamic parameters, cardiac dysfunction, histopathological and ultrastructural damages, and decreased myocardial infarction size after myocardial I/R injury ( P 〈 0.05 vs. I/R group). Compared with the cases in I/R group, myocardial ATP and NAD + content, mitochondrial function related genes and proteins, and the expressions of SOD2 and HO-1 were increased, while the expressions of ROS and Vimentin were decreased in the SPC group ( P 〈 0.05 vs. I/R group). SPC significantly activated Akt/mTOR signaling, and inhibited the formation of Vps34/Beclin1 complex via increasing expression of Bcl2 protein ( P 〈 0.05 vs. I/R group). SPC suppressed elevated expressions of LC3 II/I ratio, Beclin1, Atg5 and Atg7 in I/R rat, which indicated that SPC inhibited over-activation of autophagy, and promoted autophagosome clearance. Meanwhile, SPC significantly suppressed the decline of Opa1 and increases of Drp1 and Parkin induced by I/R injury ( P 〈 0.05 vs. I/R group). Moreover, SPC maintained the contents of ATP by reducing impaired mitochondria. Conclusion SPC protects rat hearts against I/R injury via ameliorating mitochondrial impairment, oxidative stress and rescuing autophagic clearance.

Description: by Lisa Müller, Erich Müller, Carolin Hildebrandt, Elmar Kornexl, Christian Raschner The relative age effect (RAE), which refers to an over-representation of selected athletes born early in the selection year, was proven to be present in alpine ski racing in all age categories at both national and international levels. However, the influential factors on, or the causal mechanisms of, the RAE are still unknown. Therefore, the aim of the present study was to examine three possible influential factors on the relative age effect in alpine skiing: physical performance, anthropometric characteristics and biological maturational status. The study included the investigation of 282 elite Austrian youth ski racers and 413 non-athletes (comparison group) of the same age (10–13 years) and region. Six physical performance tests were performed, body mass and height were assessed, and the age at peak height velocity (APHV) was calculated. A significant RAE was present in the ski racers. No differences were shown in the physical performance characteristics or in the calculated APHV between the relative age quarters. These results suggest that ski racers born in the last quarter can counteract the relative age disadvantages if they already present the same level of physical performance and maturational status as those born at the beginning of the year. The height and weight of ski racers born at the beginning of the year were significantly higher compared to the non-athletes, and ski racers born in relative age quarter 1 were taller and heavier compared to the ski racers of the other quarters. This indicates that the anthropometric characteristics influence the selection process in alpine ski racing, and that relatively older athletes are more likely to be selected if they exhibit advanced anthropometric characteristics.

Description: by Andrea Pelletier-Baldelli, Jessica A. Bernard, Vijay A. Mittal Social processes are key to navigating the world, and investigating their underlying mechanisms and cognitive architecture can aid in understanding disease states such as schizophrenia, where social processes are highly impacted. Evidence suggests that social processes are impaired in individuals at ultra high-risk for the development of psychosis (UHR). Understanding these phenomena in UHR youth may clarify disease etiology and social processes in a period that is characterized by significantly fewer confounds than schizophrenia. Furthermore, understanding social processing deficits in this population will help explain these processes in healthy individuals. The current study examined resting state connectivity of the salience (SN) and default mode networks (DMN) in association with facial emotion recognition (FER), an integral aspect of social processes, as well as broader social functioning (SF) in UHR individuals and healthy controls. Consistent with the existing literature, UHR youth were impaired in FER and SF when compared with controls. In the UHR group, we found increased connectivity between the SN and the medial prefrontal cortex, an area of the DMN relative to controls. In UHR youth, the DMN exhibited both positive and negative correlations with the somatosensory cortex/cerebellum and precuneus, respectively, which was linked with better FER performance. For SF, results showed that sensory processing links with the SN might be important in allowing for better SF for both groups, but especially in controls where sensory processing is likely to be unimpaired. These findings clarify how social processing deficits may manifest in psychosis, and underscore the importance of SN and DMN connectivity for social processing more generally.

Description: The effect of filler aspect ratio on the electromagnetic properties of epoxy-amine resin reinforced with carbon nanofibers is here investigated. A heat treatment at 2500 °C of carbon nanofibers seems to increase their aspect ratio with respect to as-received ones most likely due to a lowering of structural defects and the improvement of the graphene layers within the dixie cup conformation. These morphological differences revealed by Raman's spectroscopy and scanning electron microscopy analyses may be responsible for the different electrical properties of the resulting composites. The DC characterization of the nanofilled material highlights an higher electrical conductivity and a lower electrical percolation threshold for the heat-treated carbon nanofibers based composites. In fact, the electrical conductivity is about 0.107 S/m and 1.36 × 10 −3  S/m for the nanocomposites reinforced with heat-treated and as received fibers, respectively, at 1 wt. % of nanofiller loading, while the electrical percolation threshold falls in the range [0.05–0.32]wt. % for the first nanocomposites and above 0.64 wt. % for the latter. Moreover, also a different frequency response is observed since the critical frequency, which is indicative of the transition from a resistive to a capacitive-type behaviour, shifts forward of about one decade at the same filler loading. The experimental results are supported by theoretical and simulation studies focused on the role of the filler aspect ratio on the electrical properties of the nanocomposites.

Description: Analyses of the local crystal and electronic structure in the vicinity of Fe 3+ centers in perovskite KMgF 3 crystal have been carried out in a comprehensive manner. A combination of density functional theory (DFT) and a semi-empirical superposition model (SPM) is used for a complete analysis of all Fe 3+ centers in this study for the first time. Some quantitative information has been derived from the DFT calculations on both the electronic structure and the local geometry around Fe 3+ centers. All of the trigonal (K-vacancy case, K-Li substitution case, and normal trigonal Fe 3+ center case), FeF 5 O cluster, and tetragonal (Mg-vacancy and Mg-Li substitution cases) centers have been taken into account based on the previously suggested experimental and theoretical inferences. The collaboration between the experimental data and the results of both DFT and SPM calculations provides us to understand most probable structural model for Fe 3+ centers in KMgF 3 .

Description: Potassium 1,1′-dinitroamino-5,5′-bistetrazolate (K 2 DNABT) is a nitrogen rich (50.3% by weight, K 2 C 2 N 12 O 4 ) green primary explosive with high performance characteristics, namely, velocity of detonation (D = 8.33 km/s), detonation pressure (P = 31.7 GPa), and fast initiating power to replace existing toxic primaries. In the present work, we report density functional theory (DFT) calculations on structural, equation of state, vibrational spectra, electronic structure, and absorption spectra of K 2 DNABT. We have discussed the influence of weak dispersive interactions on structural and vibrational properties through the DFT-D2 method. We find anisotropic compressibility behavior (b

Description: We perform direct large molecular dynamics simulations of homogeneous SPC/E water nucleation, using up to ∼ 4 ⋅ 10 6 molecules. Our large system sizes allow us to measure extremely low and accurate nucleation rates, down to ∼ 10 19  cm −3 s −1 , helping close the gap between experimentally measured rates ∼ 10 17  cm −3 s −1 . We are also able to precisely measure size distributions, sticking efficiencies, cluster temperatures, and cluster internal densities. We introduce a new functional form to implement the Yasuoka-Matsumoto nucleation rate measurement technique (threshold method). Comparison to nucleation models shows that classical nucleation theory over-estimates nucleation rates by a few orders of magnitude. The semi-phenomenological nucleation model does better, under-predicting rates by at worst a factor of 24. Unlike what has been observed in Lennard-Jones simulations, post-critical clusters have temperatures consistent with the run average temperature. Also, we observe that post-critical clusters have densities very slightly higher, ∼ 5%, than bulk liquid. We re-calibrate a Hale-type J vs. S scaling relation using both experimental and simulation data, finding remarkable consistency in over 30 orders of magnitude in the nucleation rate range and 180 K in the temperature range.

Description: Tensor factorization of the 2-electron integral matrix is a well-known technique for reducing the computational scaling of ab initio electronic structure methods toward that of Hartree-Fock and density functional theories. The simplest factorization that maintains the positive semidefinite character of the 2-electron integral matrix is the Cholesky factorization. In this paper, we introduce a family of positive semidefinite factorizations that generalize the Cholesky factorization. Using an implementation of the factorization within the parametric 2-RDM method [D. A. Mazziotti, Phys. Rev. Lett. 101 , 253002 (2008)], we study several inorganic molecules, alkane chains, and potential energy curves and find that this generalized factorization retains the accuracy and size extensivity of the Cholesky factorization, even in the presence of multi-reference correlation. The generalized family of positive semidefinite factorizations has potential applications to low-scaling ab initio electronic structure methods that treat electron correlation with a computational cost approaching that of the Hartree-Fock method or density functional theory.

Description: Triple Langmuir Probe (TLP) is a widely used diagnostics for instantaneous measurement of electron temperature and density in low temperature laboratory plasmas as well as in edge region of fusion plasma devices. Presence of a moderately energetic flowing electron component, constituting only a small fraction of the bulk electrons, is also a generally observed scenario in plasma devices, where plasmas are produced by electron impact ionization of neutrals. A theoretical analysis of its effect on interpretation of the TLP data for bulk electron temperature measurement is presented here assuming electron velocity distribution is not deviating substantially from a Maxwellian. The study predicts conventional expression from standard TLP theory to give overestimated value of bulk electron temperature. Correction factor is significant and largely depends on population density, temperature, and energy of the fast component. Experimental verification of theoretical results is obtained in the magnetized plasma linear experimental device of Saha Institute of Nuclear Physics where plasma is produced by an electron cyclotron resonance method and known to have a fast flowing electron component.

Description: The recent energy demands affected by the dilution of conventional energy resources and the growing awareness of environmental considerations had motivated many researchers to seek for novel renewable energy conversion methods. Thermoelectric direct conversion of thermal into electrical energies is such a method, in which common compositions include IV-VI semiconducting compounds (e.g., PbTe and SnTe) and their alloys. For approaching practical thermoelectric devices, the current research is focused on electronic optimization of off-stoichiometric p -type Pb x Sn 1− x Te alloys by tuning of Bi 2 Te 3 doping and/or SnTe alloying levels, while avoiding the less mechanically favorable Na dopant. It was shown that upon such doping/alloying, higher ZT s, compared to those of previously reported undoped Pb 0.5 Sn 0.5 Te alloy, were obtained at temperatures lower than 210–340 °C, depending of the exact doping/alloying level. It was demonstrated that upon optimal grading of the carrier concentration, a maximal thermoelectric efficiency enhancement of ∼38%, compared to that of an undoped material, is expected.

Description: The properties of one-dimensional (1D) nanostructured materials can change considerably and unexpectedly, when their diameters attain the “ultrathin” level, i.e., below 10 nm. Herein, we have summarized recent developments associated with not only the synthesis but also more importantly, the applications of ultrathin 1D nanowires. Specifically, various classes of ultrathin metallic nanowires have been shown to be excellent, high-performing structural motifs for electrocatalysts, superconducting materials, electrical devices, and nano-sized pressure sensors. Moreover, the fabrication of ultrathin-based 0D-1D, 1D-1D, and 1D-2D composite hybrid structures may represent one of the most promising designs for novel architectures in energy storage and conversion, photovoltaic devices, photoconductivity, and photoelectrocatalysis.

Description: One of the grand challenges facing materials-by-design approaches for complex oxide deployment in electronic devices is how to balance transformative first-principles based predictions with experimental feasibility. Here, we briefly review the functionality-driven approach (inverse design) for materials discovery, encapsulated in three modalities for materials discovery ( m 3 D) that integrate experimental feedback. We compare it to both traditional theoretical and high-throughput database-directed approaches aimed at advancing oxide-based materials into technologies.

Description: Double cathode buffer layers (CBLs) composed of fullerene derivative functionalized with a crown-ether end group in its side chain (denoted as PCBC) and a LiF layer were introduced between the PCBM acceptor layer and the top cathode in planar p-i-n perovskite solar cells (pero-SCs) based on CH 3 NH 3 PbI 3−X Cl X . The devices with the PCBC/LiF double CBLs showed significant improvements in power conversion efficiency (PCE) and long-term stability when compared to the device with LiF single CBL. Through optimizing the spin-coating speed of PCBC, a maximum PCE of 15.53% has been achieved, which is approximately 15% higher than that of the device with single LiF CBL. The remarkable improvement in PCE can be attributed to the formation of a better ohmic contact in the CBL between PCBC and LiF/Al electrode arising from the dipole moment of PCBC, leading to the enhanced fill factor and short-circuit current density ( J sc ). Besides the PCE, the long-term stability of the devices with PCBC interlayer is also superior to that of the device with LiF single CBL, which is due to the more effective protection for the perovskite/PCBM interface.

Description: Using a combination of continuous wave and time-resolved spectroscopy, we study the effects of interfacial conditions on the radiative lifetimes and photoluminescence intensities of sub-monolayer colloidal CdTe/CdS quantum dots (QDs) embedded in a three-dimensional porous silicon (PSi) scaffold. The PSi matrix was thermally oxidized under different conditions to change the interfacial oxide thickness. QDs embedded in a PSi matrix with ∼0.4 nm of interfacial oxide exhibited reduced photoluminescence intensity and nearly five times shorter radiative lifetimes (∼16 ns) compared to QDs immobilized within completely oxidized, porous silica (PSiO 2 ) frameworks (∼78 ns). The exponential dependence of QD lifetime on interfacial oxide thickness in the PSi scaffolds suggests charge transfer plays an important role in the exciton dynamics.

Description: Schottky Barrier-MOSFET technology offers intriguing possibilities for cryogenic nano-scale devices, such as Si quantum devices and superconducting devices. We present experimental results on a device architecture where the gate electrode is self-aligned with the device channel and overlaps the source and drain electrodes. This facilitates a sub-5 nm gap between the source/drain and channel, and no spacers are required. At cryogenic temperatures, such devices function as p-MOS Tunnel FETs, as determined by the Schottky barrier at the Al-Si interface, and as a further advantage, fabrication processes are compatible with both CMOS and superconducting logic technology.

Description: We report an experimental study of the domain structure of ferroelectric YMnO 3 and YMn 0.9 Fe 0.1 O 3 using polycrystalline samples prepared by direct hydrothermal crystallisation at 240 °C, well below their structural phase transition temperatures. Powder X-ray diffraction shows the expected P 6 3 cm space group for both samples with an increase in a and a small decrease in c with Fe incorporation, consistent with an adjustment of MnO 5 tilting, while XANES spectra at the Mn and Fe K edges show the oxidation state of both metals are maintained at +3 in the doped sample. High resolution TEM shows that curved stripe, annular and vortex domains can all be observed in the YMnO 3 crystals, proving that the structural phase transition is not the only driving force for the occurrence of the annular and vortex domains. Furthermore, the absence of the annular and vortex domains in YMn 0.9 Fe 0.1 O 3 indicates that the tilting state of MnO 5 bipyramids plays an important role in the domain formation. Atomic resolution STEM images confirm that the ferroelectric domain walls correspond to structural antiphase boundaries similar to the crystals made via high temperature solid-state reactions.

Description: An infrared detector is proposed that is based on a ferroelectric tunnel junction (FTJ) working under bolometer-like principles. Electron tunneling, either direct or indirect, through the ferroelectric barrier depends on the temperature of the devices. During tunneling, infrared radiation alters the polarization of the ferroelectric film via pyroelectricity, resulting in a change in the barrier height of the tunnel junction. A high temperature coefficient of resistance of up to −3.86% was observed at room temperature. These results show that the FTJ structure has potential to be adapted for use in uncooled infrared detectors.

Description: Although magnetic heterostructures are the basis of many magnetic technologies, the mechanisms involved in magnetization reversals in such structures are not fully understood, especially in amorphous multilayers. Here, we report on the SmCo/CoAlZr system and exploit resonant magnetic x-ray scattering to probe the element specific magnetization reversals. When combined into a tri-layer structure, two different switching fields and reversal mechanisms are observed for the Sm and Co sub-lattices. We argue that the decoupling of the sub-lattices arises from the local distribution of atomic species within the amorphous matrix leading to a strong magnetic leverage effect and exchange pinning. The decoupling arises due to strong interactions between regions of high Co density which span the interface. The relatively sparse interactions between Sm and Co induce a localized pinning of the Co-rich areas, resulting in an exchange bias in minor loops and an enhanced coercivity.

Description: The room-temperature ferromagnetic behavior of MnAs/GaAs(001) thin film has been locally explored by Transmission Electron Microscope (TEM). We first differentiated hexagonal α-MnAs and quasi-hexagonal β-MnAs which are very similar in atomic structure by electron diffraction. Local magnetic moment information of the identified α-MnAs was extracted from manganese-L 2,3 edges using Energy-loss Magnetic Circular Dichroism technique and the ratio of orbital to spin magnetic moment was measured. In this experiment, atomic structure identification, chemical analysis, and magnetic moment measurement were simultaneously achieved at high spatial resolution in TEM, thus providing a potential method for in-situ study of local properties of multiphase magnetic materials.

Description: Ag 9 (SiO 4 ) 2 NO 3 was prepared by a reactive flux method. The structures, morphologies, and light absorption properties were investigated. Owing to the polar crystal structure, an internal electric field can be formed inside the material, which can facilitate the photogenerated charge separation during the photocatalytic process. Based on both the wide light absorption spectra and high charge separation efficiency originated from the polarized internal electric field, Ag 9 (SiO 4 ) 2 NO 3 exhibit higher efficiency over Ag 3 PO 4 during the degradation of organic dyes under visible light irradiation, which is expected to be a potential material for solar energy harvest and conversion.

Description: We obtained photovoltaic response in pristine multilayer WSe 2 by sandwiching WSe 2 between top and bottom metals. In this structure, the work-function difference between the top metal and WSe 2 plays a critical role in generating built-in potentials and photovoltaic responses. Our devices with Zn as top metal exhibit photo-conversion efficiencies up to 6.7% under 532 nm illumination and external quantum efficiencies in the range of 40%–83% for visible light. This work provides a method for generating photovoltaic responses in layered semiconductors without detrimental doping or exquisite heterostructures, and also advances the physics for modulating the band structures of such emerging semiconductors.

Description: We use cyclotron resonance THz-spectroscopy in pulsed magnetic fields up to 63 T to measure the electron effective mass in Si-doped GaAsN semiconductor alloys with nitrogen content up to 0.2%. This technique directly probes the transport properties of the N-modified conduction band, particularly the electron effective mass, which has been discussed controversially in the experimental and theoretical literature. We report a slight increase of the electron effective mass and nonparabolicity with N-content for different photon energies in agreement with the two-level band anticrossing model calculations. Furthermore, we show a pronounced electron mobility drop with increasing N-content.

Description: Blending the conjugated polymer poly(3-hexylthiophene) (P3HT) with the insulating electret polystyrene (PS), we show that the threshold voltage V t of organic field-effect transistors (OFETs) can be easily and reversely tuned by applying a gate bias stress at 130 °C. It is proposed that this phenomenon is caused by thermally activated charge injection from P3HT into PS matrix, and that this charge is immobilized within the PS matrix after cooling down to room temperature. Therefore, room-temperature hysteresis-free FETs with desired V t can be easily achieved. The approach is applied to reversely tune the OFET mode of operation from accumulation to depletion, and to build inverters.

Description: Reflective surfaces are one of the key elements of solar plants to concentrate energy in the receivers of solar thermal electricity plants. Polymeric substrates are being considered as an alternative to the widely used glass mirrors due to their intrinsic and processing advantages, but optimizing both the reflectance and the physical stability of polymeric mirrors still poses technological difficulties. In this work, polymeric surfaces have been functionalized with ceramic thin-films by atomic layer deposition. The characterization and optimization of the parameters involved in the process resulted in surfaces with a reflection index of 97%, turning polymers into a real alternative to glass substrates. The solution we present here can be easily applied in further technological areas where seemingly incompatible combinations of polymeric substrates and ceramic coatings occur.

Description: Understanding the coupling of different modal frequencies and their tuning mechanisms has become essential to design multi-frequency MEMS devices. In this work, we fabricate a MEMS beam with fixed boundaries separated from two side electrodes and a bottom electrode. Subsequently, we perform experiments to obtain the frequency variation of in-plane and out-of-plane mechanical modes of the microbeam with respect to both DC bias and laser heating. We show that the frequencies of the two modes coincide at a certain DC bias, which in turn can also be varied due to temperature. Subsequently, we develop a theoretical model to predict the variation of the two modes and their coupling due to a variable gap between the microbeam and electrodes, initial tension, and fringing field coefficients. Finally, we discuss the influence of frequency tuning parameters in arrays of 3, 33, and 40 microbeams, respectively. It is also found that the frequency bandwidth of a microbeam array can be increased to as high as 25 kHz for a 40 microbeam array with a DC bias of 80 V.

Description: Atomic-scale knowledge and control of oxidation of GaSb(100), which is a potential interface for energy-efficient transistors, are still incomplete, largely due to an amorphous structure of GaSb(100) oxides. We elucidate these issues with scanning-tunneling microscopy and spectroscopy. The unveiled oxidation-induced building blocks cause defect states above Fermi level around the conduction-band edge. By interconnecting the results to previous photoemission findings, we suggest that the oxidation starts with substituting second-layer Sb sites by oxygen. Adding small amount of indium on GaSb(100), resulting in a (4 × 2)-In reconstruction, before oxidation produces a previously unreported, crystalline oxidized layer of (1 × 3)-O free of gap states.

Description: A scanning transmission electron microscope equipped with a backscattered and secondary electron detector is shown capable to image graphene and hexagonal boron nitride monolayers. Secondary electron contrasts of the two lightest monolayer materials are clearly distinguished from the vacuum level. A signal difference between these two materials is attributed to electronic structure differences, which will influence the escape probabilities of the secondary electrons. Our results show that the secondary electron signal can be used to distinguish between the electronic structures of materials with atomic layer sensitivity, enhancing its applicability as a complementary signal in the analytical microscope.

Description: Refractive index sensing plays a key role in various environmental and biological sensing applications. Here, a method is presented for measuring the absolute refractive index dispersion of liquids using an array of photonic crystal resonant reflectors of varying periods. It is shown that by covering the array with a sample liquid and measuring the resonance wavelength associated with transverse electric polarized quasi guided modes as a function of period, the refractive index dispersion of the liquid can be accurately obtained using an analytical expression. This method is compact, can perform measurements at arbitrary number of wavelengths, and requires only a minute sample volume. The ability to sense a material's dispersion profile offers an added dimension of information that may be of benefit to optofluidic lab-on-a-chip applications.

Description: Brillouin microscopy is an emerging technique to yield high spatial resolution mechanical images in a non-contact manner. The main challenge in Brillouin spectroscopy is given by the detection and the localisation of the Brillouin peaks, in particular, when a high amount of elastic light is collected. We demonstrate a purely interferometric method to suppress the parasitic light which overwhelms the Brillouin spectrum using destructive interference in a Michelson interferometer. A suppression ratio of 35 dB is readily achieved. Both double and single stage virtually imaged phased array spectrometers are tested showing that the Brillouin peaks can still be measured when the intensity of the elastic light is higher by 53 dB, hence, enabling 3D mechanical imaging of thin biological systems such as cells.

Description: In earlier works, we used spheres of various sizes as impedance probes in demonstrating a method of determining plasma potential, φ p , when the probe radius is much larger than the Debye length, λ D . The basis of the method in those works [Walker et al ., Phys. Plasmas 13 , 032108 (2006); ibid . 15 , 123506 (2008); ibid . 17 , 113503 (2010)] relies on applying a small amplitude signal of fixed frequency to a probe in a plasma and, through network analyzer-based measurements, determining the complex reflection coefficient, Γ , for varying probe bias, V b . The frequency range of the applied signal is restricted to avoid sheath resonant effects and ion contributions such that ω pi  ≪ ω ≪ ω pe , where ω pi is the ion plasma frequency and ω pe is the electron plasma frequency. For a given frequency and applied bias, both Re( Z ac ) and Im( Z ac ) are available from Γ . When Re( Z ac ) is plotted versus V b , a minimum predicted by theory occurs at φ p [Walker et al ., Phys. Plasmas 17 , 113503 (2010)]. In addition, Im (Z ac ) appears at, or very near, a maximum at φ p . As n e decreases and the sheath expands, the minimum becomes harder to discern. The purpose of this work is to demonstrate that when using network analyzer-based measurements, Γ itself and Im (Z ac ) and their derivatives are useful as accompanying indicators to Re( Z ac ) in these difficult cases. We note the difficulties encountered by the most commonly used plasma diagnostic, the Langmuir probe. Spherical probe data is mainly used in this work, although we present limited data for a cylinder and a disk. To demonstrate the effect of lowered density as a function of probe geometry, we compare the cylinder and disk using only the indicator Re( Z ac ).

Description: The classical gravitational instability of a layer of denser fluid overlying a layer of less dense fluid, commonly known as the Rayleigh-Taylor instability, has been studied for well over a hundred years. In this article, we present the results of numerical simulations of a variant of this instability in which a plug of dense fluid is released from rest in a thin channel between two flat, vertical walls, causing a downward acceleration of the entire fluid column and formation of boundary layers near the walls. The plug of dense fluid undergoes distinctly different evolution near the walls and in the fluid interior. The instability in the interior, which we label the “hammerhead” instability based on its shape, is robust over a range of physical parameters, but disappears below a threshold Schmidt number. Fluid near the wall is slowed, and thin tendrils that link the near wall fluid to the main body of the fluid plug form, and in some cases undergo their own instability. We characterize the fully three-dimensionalized state, finding that while bulk measures of kinetic energy three-dimensionalization do not discriminate between low and high Schmidt number cases, the geometric distributions of the dynamical parameters Q and R from the turbulence literature are profoundly different in the high Schmidt number case. Finally, we consider the role of shear in situations in which the two plates are not exactly vertical, demonstrating that shear diminishes the importance of three-dimensionalization, while the hammerhead instability remains relevant.

Description: Flow past two cylinders of different diameters in close proximity is simulated numerically for a constant diameter ratio of 0.45, a gap ratio of 0.0625, and a Reynolds number of 1000 (defined using the diameter of the main cylinder). The effect of the position angle α of the small cylinder relative to the large one on force coefficients and wake flow patterns are studied. Depending on the position angle α of the small cylinder, four wake flow modes are identified: the upstream interference mode for α = 0°, 22.5°, and 45°, the intermittent attached gap flow mode for α = 67.5° and 90°, the attached gap flow mode for α = 112.5° and 135°, and the wake interference mode for α = 157.5° and 180°. The RMS lift coefficients of both cylinders are reduced significantly compared with that of a single cylinder, regardless of the position angle of the small cylinder. Although the variation trends of the mean drag and lift coefficients with the position angle of the small cylinder obtained from the two-dimensional (2D) and three-dimensional (3D) simulations are similar, the 2D simulations overestimate the mean drag coefficient, the RMS drag and lift coefficients compared with those obtained from the 3D simulations.

Description: Farley-Buneman modes are an example of the collisional instability, which is thought to be the dominant mechanism for the irregularities in low ionosphere region. Despite high collisionality due to electron-neutral and ion-neutral collisions, the kinetic effects associated with finite temperature are important for determination of the mode frequencies and growth rate. This is especially important for ion component that is largely unmagnetized due to low ion cyclotron frequency. The ion thermal effects are strongly pronounced for shorter wavelengths and are crucial for the growth rate cut-off at high wavenumbers. We develop an extended fluid model for ion dynamics to incorporate the effects of ion thermal motion. The model is based on the extended MHD model that includes the evolution equations for higher order moments such as ion viscosity and ion heat flux. We also develop the generalized Chapman-Enskog closure model that provides exact linear closures based on the linearized kinetic equation. The results of these models are compared and tested against the linear kinetic model. The dispersion of Farley-Buneman modes and growth rate behavior are investigated in the short wavelength region.

Description: by Marc O. Nadon, Jerald S. Ault, Ivor D. Williams, Steven G. Smith, Gerard T. DiNardo The coral reef fish community of Hawaii is composed of hundreds of species, supports a multimillion dollar fishing and tourism industry, and is of great cultural importance to the local population. However, a major stock assessment of Hawaiian coral reef fish populations has not yet been conducted. Here we used the robust indicator variable “average length in the exploited phase of the population (L¯)”, estimated from size composition data from commercial fisheries trip reports and fishery-independent diver surveys, to evaluate exploitation rates for 19 Hawaiian reef fishes. By and large, the average lengths obtained from diver surveys agreed well with those from commercial data. We used the estimated exploitation rates coupled with life history parameters synthesized from the literature to parameterize a numerical population model and generate stock sustainability metrics such as spawning potential ratios (SPR). We found good agreement between predicted average lengths in an unfished population (from our population model) and those observed from diver surveys in the largely unexploited Northwestern Hawaiian Islands. Of 19 exploited reef fish species assessed in the main Hawaiian Islands, 9 had SPRs close to or below the 30% overfishing threshold. In general, longer-lived species such as surgeonfishes, the redlip parrotfish ( Scarus rubroviolaceus ), and the gray snapper ( Aprion virescens ) had the lowest SPRs, while short-lived species such as goatfishes and jacks, as well as two invasive species ( Lutjanus kasmira and Cephalopholis argus ), had SPRs above the 30% threshold.

Description: by Leonie J. P. Steenis, Marjolein Verhoeven, Dave J. Hessen, Anneloes L. van Baar Background The Bayley Scales of Infant and Toddler Development-third edition (Bayley-III) are frequently used to assess early child development worldwide. However, the original standardization only included US children, and it is still unclear whether or not these norms are adequate for use in other populations. Recently, norms for the Dutch version of the Bayley-III (The Bayley-III-NL) were made. Scores based on Dutch and US norms were compared to study the need for population-specific norms. Methods Scaled scores based on Dutch and US norms were compared for 1912 children between 14 days and 42 months 14 days. Next, the proportions of children scoring 〈 1-SD and 〈 -2 SD based on the two norms were compared, to identify over- or under-referral for developmental delay resulting from non-population-based norms. Results Scaled scores based on Dutch norms fluctuated around values based on US norms on all subtests. The extent of the deviations differed across ages and subtests. Differences in means were significant across all five subtests (p 〈 .01) with small to large effect sizes ( η p 2 ) ranging from .03 to .26). Using the US instead of Dutch norms resulted in over-referral regarding gross motor skills, and under-referral regarding cognitive, receptive communication, expressive communication, and fine motor skills. Conclusions The Dutch norms differ from the US norms for all subtests and these differences are clinically relevant. Population specific norms are needed to identify children with low scores for referral and intervention, and to facilitate international comparisons of population data.

Description: by Xiao-Dan Wang, Hui Lu, Zhihong Shi, Li Cai, Shuai Liu, Shuling Liu, Tong Han, Ying Wang, Yuying Zhou, Xinping Wang, Shuo Gao, Yong Ji Posterior cortical atrophy (PCA) is a clinicoradiologic neurodegenerative syndrome characterized by predominant impairment of higher visual functions. Neuroimaging and neuropathological studies show that PCA is probably an atypical presentation of Alzheimer’s disease. However, in China PCA has rarely been studied and remains largely unknown. Our study therefore aimed to analyze the clinical manifestations and patterns of cerebral atrophy, amyloid beta deposition and regional glucose metabolism in Chinese PCA patients, comparing them directly with those of typical Alzheimer’s disease (TAD). Seven PCA patients, 6 TAD patients and 5 controls underwent neuropsychological assessment, MRI scan, 11 C-PIB PET scan and 18 F-FDG PET scan. Cerebral atrophy including ventricular enlargement, posterior atrophy and medial temporal lobe atrophy were evaluated with MRI. The uptake of 11 C-PIB was quantified at the voxel level using the standardized uptake value ratio. Comparisons of regional cerebral glucose metabolism were calculated with statistical parametric mapping. PCA patients showed significant impairment on visuospatial function in neuropsychological assessment. And PCA patients showed more severe posterior atrophy and less severe left medial temporal lobe atrophy compared with TAD patients. The data from 11 C-PIB PET scanning showed that amyloid beta deposition in PCA was comparable to TAD. Moreover, in PCA the results from 18 F-FDG PET scanning revealed significant hypometabolism in the temporoparietooccipital region and identified specific hypometabolism in the right occipital lobe, compared with TAD. Our study thus provides a preliminary view of PCA in Chinese patients. A further study with a larger number of subjects would be recommended to confirm these findings.

Description: by Q. Wang, M. Li, Edmond H. M. Lou, M. S. Wong Background Non-ionizing radiation imaging assessment has been advocated for the patients with adolescent idiopathic scoliosis (AIS). As one of the radiation-free methods, ultrasound imaging has gained growing attention in scoliosis assessment over the past decade. The center of laminae (COL) method has been proposed to measure the spinal curvature in the coronal plane of ultrasound image. However, the reliability and validity of this ultrasound method have not been validated in the clinical setting. Objectives To evaluate the reliability and validity of clinical ultrasound imaging on lateral curvature measurements of AIS with their corresponding magnetic resonance imaging (MRI) measurements. Methods Thirty curves (ranged 10.2°–68.2°) from sixteen patients with AIS were eligible for this study. The ultrasound scan was performed using a 3-D ultrasound unit within the same morning of MRI examination. Two researchers were involved in data collection of these two examinations. The COL method was used to measure the coronal curvature in ultrasound image, compared with the Cobb method in MRI. The intra- and inter-rater reliability of the COL method was evaluated by intra-class correlation coefficient (ICC). The validity of this method was analyzed by paired Student’s t -test, Bland–Altman statistics and Pearson correlation coefficient. The level of significance was set as 0.05. Results The COL method showed high intra- and inter-rater reliabilities (both with ICC (2, K) 〉0.9, p

Description: by Yongkang Kim, Taesung Park Genome-wide association studies (GWAS) have successfully discovered hundreds of associations between genetic variants and complex traits. Most GWAS have focused on the identification of single variants. It has been shown that most of the variants that were discovered by GWAS could only partially explain disease heritability. The explanation for this missing heritability is generally believed to be gene-gene (GG) or gene-environment (GE) interactions and other structural variants. Generalized multifactor dimensionality reduction (GMDR) has been proven to be reasonably powerful in detecting GG and GE interactions; however, its performance has been found to decline when outlying quantitative traits are present. This paper proposes a robust GMDR estimation method (based on the L-estimator and M-estimator estimation methods) in an attempt to reduce the effects caused by outlying traits. A comparison of robust GMDR with the original MDR based on simulation studies showed the former method to outperform the latter. The performance of robust GMDR is illustrated through a real GWA example consisting of 8,577 samples from the Korean population using the Homeostasis Model Assessment of Insulin Resistance (HOMA-IR) level as a phenotype. Robust GMDR identified the KCNH1 gene to have strong interaction effects with other genes on the function of insulin secretion.

Description: by Min Gao, Renli Tian, Junhao Wen, Qingyu Xiong, Bin Ling, Linda Yang In recent years, recommender systems have become an effective method to process information overload. However, recommendation technology still suffers from many problems. One of the problems is shilling attacks-attackers inject spam user profiles to disturb the list of recommendation items. There are two characteristics of all types of shilling attacks: 1) Item abnormality: The rating of target items is always maximum or minimum; and 2) Attack promptness: It takes only a very short period time to inject attack profiles. Some papers have proposed item anomaly detection methods based on these two characteristics, but their detection rate, false alarm rate, and universality need to be further improved. To solve these problems, this paper proposes an item anomaly detection method based on dynamic partitioning for time series. This method first dynamically partitions item-rating time series based on important points. Then, we use chi square distribution (χ 2 ) to detect abnormal intervals. The experimental results on MovieLens 100K and 1M indicate that this approach has a high detection rate and a low false alarm rate and is stable toward different attack models and filler sizes.

Description: by Morgan Kruse, Rebecca Wildner, Gisoo Barnes, Monique Martin, Udo Mueller, Francesco Lo-Coco, Ashutosh Pathak The objective of this study was to estimate the net cost of arsenic trioxide (ATO) added to all- trans retinoic acid (ATRA) compared to ATRA plus chemotherapy when used in first-line acute promyelocytic leukemia (APL) treatment for low to intermediate risk patients from the perspective of the overall Italian healthcare systemA Markov model was developed with 3 health states: stable disease, disease event and death. Each month, patients could move from stable to disease event or die from either state. After a disease event, patients discontinued initial treatment and switched to the other regimen as second-line therapy. Treatment regimens, efficacy and adverse events were derived from published sources and expert opinion; unit costs were collected from standard Italian sources. Clinical outcomes and costs for pre-ATO and post-ATO scenarios were combined with population and product utilization information to calculate the total budgetary impact using a 3-year time horizon; one-way sensitivity analyses were conducted. Three-year cumulative pharmacy costs for ATO+ATRA were €46,700 per-patient versus €6,500 for ATRA+chemotherapy; however, medical costs for ATO+ATRA were €12,300 per-patient versus €30,200 for ATRA+chemotherapy. The total budgetary impact was estimated to be an additional €127,300, €312,500 and €477,800 in the first, second and third years, respectively. The model was most sensitive to changes in the cost of the ATO+ATRA regimen during the consolidation phase. Budgetary impact models are valuable to payers making formulary decisions regarding the access and affordability of new medicines. The cost of treatment analysis showed that pharmacy costs for ATO+ATRA were higher than for ATRA+chemotherapy, while all other evaluated costs were lower for ATO+ATRA treated patients. The average budgetary impact was €305,900 per year overall, representing a 3.5% increase. Further research is needed to determine the cost-effectiveness of ATO+ATRA compared to the current first-line standard of care in APL.

Description: by Antonella Agodi, Martina Barchitta, Annalisa Quattrocchi, Andrea Maugeri, Manlio Vinciguerra Objective The Death-Associated Protein Kinase 1 ( DAPK1 ) gene has been frequently investigated in cervical cancer (CC). The aim of the present study was to carry out a systematic review and a meta-analysis in order to evaluate DAPK1 promoter methylation as an epigenetic marker for CC risk. Methods A systematic literature search was carried out. The Cochrane software package Review Manager 5.2 was used. The fixed-effects or random-effects models, according to heterogeneity across studies, were used to calculate odds ratios (ORs) and 95% Confidence Intervals (CIs). Furthermore, subgroup analyses were conducted by histological type, assays used to evaluate DAPK1 promoter methylation, and control sample source. Results A total of 20 papers, published between 2001 and 2014, on 1929 samples, were included in the meta-analysis. DAPK1 promoter methylation was associated with an increased CC risk based on the random effects model (OR: 21.20; 95%CI = 11.14–40.35). Omitting the most heterogeneous study, the between study heterogeneity decreased and the association increased (OR: 24.13; 95% CI = 15.83–36.78). The association was also confirmed in all the subgroups analyses. Conclusions A significant strong association between DAPK1 promoter methylation and CC was shown and confirmed independently by histological tumor type, method used to evaluate methylation and source of control samples. Methylation markers may have value in early detection of CC precursor lesions, provide added reassurances of safety for women who are candidates for less frequent screens, and predict outcomes of women infected with human papilloma virus.

Description: by Yufeng Huang, Chuchu Wang, Yufeng Yao, Xiaoyu Zuo, Shanshan Chen, Chengqi Xu, Hongfu Zhang, Qiulun Lu, Le Chang, Fan Wang, Pengxia Wang, Rongfeng Zhang, Zhenkun Hu, Qixue Song, Xiaowei Yang, Cong Li, Sisi Li, Yuanyuan Zhao, Qin Yang, Dan Yin, Xiaojing Wang, Wenxia Si, Xiuchun Li, Xin Xiong, Dan Wang, Yuan Huang, Chunyan Luo, Jia Li, Jingjing Wang, Jing Chen, Longfei Wang, Li Wang, Meng Han, Jian Ye, Feifei Chen, Jingqiu Liu, Ying Liu, Gang Wu, Bo Yang, Xiang Cheng, Yuhua Liao, Yanxia Wu, Tie Ke, Qiuyun Chen, Xin Tu, Robert Elston, Shaoqi Rao, Yanzong Yang, Yunlong Xia, Qing K. Wang Atrial fibrillation (AF) is the most common cardiac arrhythmia at the clinic. Recent GWAS identified several variants associated with AF, but they account for

Description: Ultrafast energy relaxation process in Bi 2 Te 3 thin films is studied using a collinear two color pump-probe technique. The coherent optical phonon is enhanced and destroyed by changing the separation times of double pump pulses. The non-oscillatory component of the reflectivity trace after the second pump pulse shows a distinct difference with and without the presence of coherent optical phonons, thus providing a direct evidence of the effect of optical phonon on the hot carrier relaxation process. The deduced characteristic times are systematically smaller when coherent optical phonons are involved in the energy transfer process. Comparatively, the conventional relaxation process is relatively slow, which is explained by the screening effect of the incoherent optical phonon. This work suggests that the energy relaxation can be manipulated through the excitation of coherent optical phonons.

Description: Using first-principles calculations, we show that the conduction and valence band energies and their deformation potentials exhibit a non-negligible compositional bowing in strained ternary semiconductor alloys such as InGaAs. The electronic structure of these compounds has been calculated within the framework of local density approximation and hybrid functional approach for large cubic supercells and special quasi-random structures, which represent two kinds of model structures for random alloys. We find that the predicted bowing effect for the band energy deformation potentials is rather insensitive to the choice of the functional and alloy structural model. The direction of bowing is determined by In cations that give a stronger contribution to the formation of the In x Ga 1− x As valence band states with x ≳ 0.5, compared to Ga cations.

Description: Magnetic, dielectric, and ac conductivity as well as room temperature structural and Raman studies are performed on double perovskite Dy 2 NiMnO 6 . The crystal structure of the compound adopts monoclinic P2 1 /n space group, where alternate Mn and Ni distorted octahedral are arranged in anti-phase a − a − b + order in Glazer notation. Magnetization studies show two magnetic transitions around 100 K and 20 K which are related to the ordering of transition and rare earth cations moment, respectively. Temperature dependent dielectric permittivity shows Havriliak-Negami type thermally activated dielectric relaxation. The ac conductivity at different temperature is found to follow Jonscher power law behavior. Time-temperature scaling of the conductivity spectra reveals that the charge transport dynamics is independent of temperature. Intriguingly, an anomaly in the dielectric constant is observed close to the order of Dy moment which indicates intrinsic magnetoelectric coupling. The hybridization between Dy and Ni/Mn is suggested to be correlated with the magnetoelectric coupling.

Description: The stable configurations and electronic and magnetic properties of nonmetal atoms (H, N, P, O, S, F, and Cl) adsorbed ReS 2 monolayers have been investigated by first-principles calculations. It is found that H, O, S, F, and Cl prefer to occupy the peak sites of S atoms, while both N and P atoms favor the valley sites of S atoms. The ReS 2 sheet exhibits a good adsorption capability to nonmetal atoms. The reconstruction of the surface is pronounced in N- and P-adsorbed ReS 2 monolayers. In H-adsorbed case, the Fermi level is pulled into the conduction band, which results in the semiconductor-metal transition. The same magnetic moment of 1 μ B is found in the N-, P-, F-, and Cl-adsorbed ReS 2 monolayers, while the mechanisms of forming magnetic moment for N (P)- and F (Cl)-adsorbed cases are different. In addition, the spatial extensions of spin density in P-, F-, and Cl-adsorbed cases are larger than that in N-adsorbed case, which is more suitable to achieve long-range magnetic coupling interaction at low defect concentrations. Our results provide insight for achieving metal-free magnetism and a tunable band gap for various electronic and spintronic devices based on ReS 2 .

Description: Three different chemical solutions are used to remove the possible contamination on GaN surface, while Ga 2 O 3 is still found at the surface. After thermal annealing at 710 °C in the ultrahigh vacuum (UHV) chamber and activated with Cs/O, all the GaN samples are successfully activated to the effective negative electron affinity (NEA) photocathodes. Among all samples, the GaN sample with the highest content of Ga 2 O 3 after chemical cleaning obtains the highest quantum efficiency. By analyzing the property of Ga 2 O 3 , the surface processing results, and electron affinity variations during Cs and Cs/O 2 deposition on GaN of other groups, it is suggested that before the adsorption of Cs, Ga 2 O 3 is not completely removed from GaN surface in our samples, which will combine with Cs and lead to a large decrease in electron affinity. Furthermore, the effective NEA is formed for GaN photocathode, along with the surface downward band bending. Based on this assumption, a new dipole model Ga 2 O 3 -Cs is suggested, and the experimental effects are explained and discussed.

Description: The phase transitions and ferroelectricity of LiNbO 3 and LiTaO 3 have been investigated theoretically from first principles. The phonon analyses and the molecular dynamics simulations revealed that the ferroelectric phase transition is not conventional displacive type but order-disorder type with strong correlation between cation displacements. According to the evaluated potential energy surfaces around the paraelectric structures, the large difference in ferroelectricity between the two oxides results from the little difference in short-range interionic interaction between Nb-O and Ta-O. As the results of the crystal orbital overlap population analyses, the different short-range interaction originates from the difference in covalency between Nb4 d -O2 p and Ta5 d -O2 p orbitals, particularly d xz - p x / d yz - p y orbitals ( π orbitals), from the electronic point of view.

Description: The reported values of bandgap of rutile GeO 2 calculated by the standard density functional theory within local-density approximation (LDA)/generalized gradient approximation (GGA) show a wide variation (∼2 eV), whose origin remains unresolved. Here, we investigate the reasons for this variation by studying the electronic structure of rutile-GeO 2 using many-body perturbation theory within the GW framework. The bandgap as well as valence bandwidth at Γ-point of rutile phase shows a strong dependence on volume change, which is independent of bandgap underestimation problem of LDA/GGA. This strong dependence originates from a change in hybridization among O- p and Ge-( s and p ) orbitals. Furthermore, the parabolic nature of first conduction band along X-Γ-M direction changes towards a linear dispersion with volume expansion.

Description: Carrier-type control of spin-glass (cluster spin-glass) is studied in order to engineer basic magnetic semiconductor elements using the memory functions of spin-glass. A key of carrier-polarity control in magnetite is the valence engineering between Fe(II) and Fe(III) that is achieved by Ti(IV) substitution. Single phases of (001)-oriented Fe 3− x Ti x O 4 thin films have been obtained on spinel MgAl 2 O 4 substrates by pulsed laser deposition. Thermoelectric power measurements reveal that Ti-rich films ( x  = 0.8) show p -type conduction, while Ti-poor films ( x  = 0.6–0.75) show n -type conduction. The systematic Fe(III) reduction to Fe(II) followed by Ti(IV) substitution in the octahedral sublattice is confirmed by the X-ray absorption spectra. All of the Fe 3− x Ti x O 4 films ( x  = 0.6–0.8) exhibit ferrimagnetism above room temperature. Next, the spin-glass behaviors of Ti-rich Fe 2.2 Ti 0.8 O 4 film are studied, since this magnetically diluted system is expected to exhibit the spin-glass behaviors. The DC magnetization and AC susceptibility measurements for the Ti-rich Fe 2.2 Ti 0.8 O 4 film reveal the presence of the spin glass phase. Thermal- and magnetic-field-history memory effects are observed and are attributed to the long time-decay nature of remanent magnetization. The detailed analysis of the time-dependent thermoremanent magnetization reveals the presence of the cluster spin glass state.

Description: We study the pair complexation of a single, highly charged polyelectrolyte (PE) chain (of 25 or 50 monomers) with like-charged patchy protein models (CPPMs) by means of implicit-solvent, explicit-salt Langevin dynamics computer simulations. Our previously introduced set of CPPMs embraces well-defined zero-, one-, and two-patched spherical globules each of the same net charge and (nanometer) size with mono- and multipole moments comparable to those of globular proteins with similar size. We observe large binding affinities between the CPPM and the like-charged PE in the tens of the thermal energy, k B T , that are favored by decreasing salt concentration and increasing charge of the patch(es). Our systematic analysis shows a clear correlation between the distance-resolved potentials of mean force, the number of ions released from the PE, and CPPM orientation effects. In particular, we find a novel two-site binding behavior for PEs in the case of two-patched CPPMs, where intermediate metastable complex structures are formed. In order to describe the salt-dependence of the binding affinity for mainly dipolar (one-patched) CPPMs, we introduce a combined counterion-release/Debye-Hückel model that quantitatively captures the essential physics of electrostatic complexation in our systems.

Description: We introduce a set of charged patchy particle models (CPPMs) in order to systematically study the influence of electrostatic charge patchiness and multipolarity on macromolecular interactions by means of implicit-solvent, explicit-ion Langevin dynamics simulations employing the Gromacs software. We consider well-defined zero-, one-, and two-patched spherical globules each of the same net charge and (nanometer) size which are composed of discrete atoms. The studied mono- and multipole moments of the CPPMs are comparable to those of globular proteins with similar size. We first characterize ion distributions and electrostatic potentials around a single CPPM. Although angle-resolved radial distribution functions reveal the expected local accumulation and depletion of counter- and co-ions around the patches, respectively, the orientation-averaged electrostatic potential shows only a small variation among the various CPPMs due to space charge cancellations. Furthermore, we study the orientation-averaged potential of mean force (PMF), the number of accumulated ions on the patches, as well as the CPPM orientations along the center-to-center distance of a pair of CPPMs. We compare the PMFs to the classical Derjaguin-Verwey-Landau-Overbeek theory and previously introduced orientation-averaged Debye-Hückel pair potentials including dipolar interactions. Our simulations confirm the adequacy of the theories in their respective regimes of validity, while low salt concentrations and large multipolar interactions remain a challenge for tractable theoretical descriptions.

Description: by Shu-I Wu, Su-Chiu Chen, Shen-Ing Liu, Fang-Ju Sun, Jimmy J. M. Juang, Hsin-Chien Lee, Kai-Liang Kao, Michael E. Dewey, Martin Prince, Robert Stewart Objective Despite high mortality associated with serious mental illness, risk of acute myocardial infarction (AMI) remains unclear, especially for patients with bipolar disorder. The main objective was to investigate the relative risk of AMI associated with schizophrenia and bipolar disorders in a national sample. Method Using nationwide administrative data, an 11-year historic cohort study was assembled, comprised of cases aged 18 and above who had received a diagnosis of schizophrenia or bipolar disorder, compared to a random sample of all other adults excluding those with diagnoses of serious mental illness. Incident AMI as a primary diagnosis was ascertained. Hazard ratios stratified by age and gender were calculated and Cox regression models were used to adjust for other covariates. Results A total of 70,225 people with schizophrenia or bipolar disorder and 207,592 people without serious mental illness were compared. Hazard ratios in men adjusted for age, income and urbanization were 1.15 (95% CI 1.01~1.32) for schizophrenia and 1.37 (1.08~1.73)for bipolar disorder, and in women, 1.85 (1.58~2.18) and 1.88(1.47~2.41) respectively. Further adjustment for treated hypertension, diabetes and hyperlipidaemia attenuated the hazard ratio for men with schizophrenia but not the other comparison groups. Hazard ratios were significantly stronger in women than men and were stronger in younger compared to older age groups for both disorders; however, gender modification was only significant in people with schizophrenia, and age modification only significant in people with bipolar disorder. Conclusions In this large national sample, schizophrenia and bipolar disorder were associated with raised risk of AMI in women and in the younger age groups although showed differences in potential confounding and modifying factors.

Description: A high-speed impedance measurement system was developed, which enables the measurement of various characteristics of CW and pulsed plasmas with time resolution of less than a microsecond. For this system, a voltage and current sensor is implemented in a printed circuit board to sense the radio frequency signals. A digital board, which has a high-speed analog to digital converter and a field-programmable gate-array, is used to calculate the impedance of the signal. The final output of impedance is measured and stored with a maximum speed of 3 Msps. This sensor system was tested in a pulsed-plasma by applying it to the point between the matching box and the plasma chamber. The experimental equipment was constructed connecting the matching box, a 13.56 MHz generator, a 2 MHz generator that produced pulsed power, and a pulse-signal generator. From the temporal behavior of the measured impedance, we were able to determine the time intervals of transient states, especially of the initial active state. This information can be used to set the pulse frequency and duty for plasma processing.

Description: The type of the Electron String Ion Sources (ESIS) is considered to be the appropriate one to produce pulsed C 4+ and C 6+ ion beams for cancer therapy accelerators. In fact, the new test ESIS Krion-6T already now provides more than 10 10 C 4+ ions per pulse and about 5 × 10 9 C 6+ ions per pulse. Such ion sources could be suitable to apply at synchrotrons. It has also been found that Krion-6T can provide more than 10 11 C 6+ ions per second at the 100 Hz repetition rate, and the repetition rate can be increased at the same or larger ion output per second. This makes ESIS applicable at cyclotrons as well. ESIS can be also a suitable type of ion source to produce the 11 C radioactive ion beams. A specialized cryogenic cell was experimentally tested at the Krion-2M ESIS for pulse injection of gaseous species into the electron string. It has been shown in experiments with stable methane that the total conversion efficiency of methane molecules to C 4+ ions reached 5%÷10%. For cancer therapy with simultaneous irradiation and precise dose control (positron emission tomography) by means of 11 C, transporting to the tumor with the primary accelerated 11 C 4+ beam, this efficiency is preliminarily considered to be large enough to produce the 11 C 4+ beam from radioactive methane and to inject this beam into synchrotrons.

Description: by Kwi Young Kang, In Je Kim, Min A Yoon, Yeon Sik Hong, Sung-Hwan Park, Ji Hyeon Ju Objective To study the relationship between inflammatory and structural lesions in the sacroiliac joints (SIJs) on MRI and spinal progression observed on conventional radiographs in patients with axial spondyloarthritis (axSpA). Methods One hundred and ten patients who fulfilled the ASAS axSpA criteria were enrolled. All underwent SIJ MRI at baseline and lumbar spine radiographs at baseline and after 2 years. Inflammatory and structural lesions on SIJ MRI were scored using the SPondyloArthritis Research Consortium of Canada (SPARCC) method. Spinal radiographs were scored using the Stoke AS Spinal Score (SASSS). Multivariate logistic regression analysis was performed to identify predictors of spinal progression. Results Among the 110 patients, 25 (23%) showed significant radiographic progression (change of SASSS≥2) over 2 years. There was no change in the SASSS over 2 years according to the type of inflammatory lesion. Patients with fat metaplasia or ankyloses on baseline MRI showed a significantly higher SASSS at 2 years than those without (p

Description: Magnetically tunable microwave bandpass filter structure have been designed and prepared by filling the ferrite rods into the metallic slits. The electromagnetic wave cannot propagate through the metallic slits. By filling the ferrite rods into the metallic slits, an enhanced optical transmission is obtained, which can be ascribed to the ferromagnetic resonance of the ferrite rods. Both the experimental and the simulated results show the center frequency and bandwidth of the passband can be tuned by the applied magnetic field, which exhibits a magnetically tunable behavior. This approach opens a way for designing tunable microwave bandpass filters.

Description: In electrolyte solutions, an electric potential difference, called the Ionic Vibration Potential (IVP), related to the ionic vibration intensity, is generated by the application of an acoustic wave. Several theories based on a mechanical framework have been proposed over the years to predict the IVP for high ionic strengths, in the case where interactions between ions have to be accounted for. In this paper, it is demonstrated that most of these theories are not consistent with Onsager’s reciprocal relations. A new expression for the IVP will be presented that does fulfill the Onsager’s reciprocal relations. We obtained this expression by deriving general expressions of the corrective forces describing non-ideal effects in electrolyte solutions.

Description: In the framework of irreversible thermodynamics, we show that the sedimentation current in electrolyte solutions is mathematically equivalent to the low frequency limit of the ionic vibration current, appearing in the presence of an acoustic wave. This non-trivial result is obtained thanks to a careful choice of the reference frame used to express the mass fluxes in the context of electroacoustics. Coupled transport phenomena in electrolyte solutions can also be investigated in a mechanical framework, with a set of Newtonian equations for the dynamics of charged solutes. Both in the context of sedimentation and of electroacoustics, we show that the results obtained in the mechanical framework, in the ideal case (i.e., without interactions between ions), do satisfy the Onsager’s reciprocal relations. We also derive the general relation between corrective forces accounting for ionic interactions which must be fulfilled so that the Onsager’s reciprocal relations are verified. Finally, we show that no additional diffusion term needs to be taken into account in the flux of solutes (far from the walls), even if local concentration gradients exist, contrarily to what was done previously in the literature.

Description: Polyacenes in their armchair geometry (phenacenes) have recently been found to possess appealing electronic and optical properties with higher chemical stability and comparatively larger band gap as compared to linear polyacenes. They also behave as high-temperature superconductors upon alkali metal doping. Moreover, the optical properties of crystalline picene can be finely tuned by applying external pressure. We investigated the variation of optical gap as a function of altering the interplanar distances between parallel cofacial phenacene dimers. We employed both time-dependent density functional theory and density matrix renormalization group (DMRG) technique to investigate the lowest singlet excitations in phenacene dimer. Our study showed that the lowest singlet excitation in these systems evolved as a function of interplanar separation. The optical excitation energy gap decreases as a function of inverse interplanar separation of the phenacene dimer. The distant dependent variation of optical absorption at the dimer level may be comparable with experimental observation in picene crystal under pressure. DMRG study also demonstrates that besides picene, electronic properties of higher phenacenes can also be tunable by altering interplanar separation.

Description: A combined experimental and theoretical study is presented of fluctuations observed by field ion microscopy in the catalytic reaction of water production on a rhodium tip. A stochastic approach is developed to provide a comprehensive understanding of the different phenomena observed in the experiment, including burst noise manifesting itself in a bistability regime, noisy oscillations, and nanopatterns with a cross-like oxidized zone separating the surface into four quadrants centered on the {111} facets. The study is based on a stochastic model numerically simulating the processes of adsorption, desorption, reaction, and transport. The surface diffusion of hydrogen is described as a percolation process dominated by large clusters corresponding to the four quadrants. The model reproduces the observed phenomena in the ranges of temperature, pressures, and electric field of the experiment.

Description: A Gaussian- Sinc basis set methodology is presented for the calculation of the electronic structure of atoms and molecules at the Hartree–Fock level of theory. This methodology has several advantages over previous methods. The all-electron electronic structure in a Gaussian- Sinc mixed basis spans both the “localized” and “delocalized” regions. A basis set for each region is combined to make a new basis methodology—a lattice of orthonormal sinc functions is used to represent the “delocalized” regions and the atom-centered Gaussian functions are used to represent the “localized” regions to any desired accuracy. For this mixed basis, all the Coulomb integrals are definable and can be computed in a dimensional separated methodology. Additionally, the Sinc basis is translationally invariant, which allows for the Coulomb singularity to be placed anywhere including on lattice sites. Finally, boundary conditions are always satisfied with this basis. To demonstrate the utility of this method, we calculated the ground state Hartree–Fock energies for atoms up to neon, the diatomic systems H 2 , O 2 , and N 2 , and the multi-atom system benzene. Together, it is shown that the Gaussian- Sinc mixed basis set is a flexible and accurate method for solving the electronic structure of atomic and molecular species.

Description: The hierarchical equations of motion (HEOM) method has recently emerged as an effective approach to simulate linear and nonlinear spectroscopic signals of molecular aggregates in the intermediate coupling regime. However, its application to large systems is still limited when there are a large number of molecules in the molecular aggregate. In this work, we propose a time domain two-particle approximation (TPA) in combination with the HEOM method to calculate the absorption and circular dichroism line shapes of molecular aggregates. The new method is shown to reduce the number of auxiliary density operators (ADOs) significantly for large systems, and a further truncation of the two-bath-set excited terms based on geometric considerations can lead to a linear increase of the number of ADOs with the system size. The validity of the HEOM-TPA method is first tested on one-dimensional model systems. The new method is then applied to calculate the absorption and circular dichroism line shapes of the Photosystem I core complex, as well as the population evolution of the Fenna-Matthews-Olson complex to demonstrate its effectiveness.

Description: We consider a system consisting of two interacting qubits that are individually coupled to separate heat baths at different temperatures. The quantum effects in heat transport are investigated in a numerically rigorous manner with a hierarchial equations of motion (HEOM) approach for non-perturbative and non-Markovian system-bath coupling cases under non-equilibrium steady-state conditions. For a weak interqubit interaction, the total system is regarded as two individually thermostatted systems, whereas for a strong interqubit interaction, the two-qubit system is regarded as a single system coupled to two baths. The roles of quantum coherence (or entanglement) between the two qubits (q-q coherence) and between the qubit and bath (q-b coherence) are studied through the heat current calculated for various strengths of the system-bath coupling and interqubit coupling for high and low temperatures. The same current is also studied using the time convolutionless (TCL) Redfield equation and using an expression derived from the Fermi golden rule (FGR). We find that the HEOM results exhibit turnover behavior of the heat current as a function of the system-bath coupling strength for all values of the interqubit coupling strength, while the results obtained with the TCL and FGR approaches do not exhibit such behavior, because they do not possess the capability of treating the q-b and q-q coherences. The maximum current is obtained in the case that the q-q coherence and q-b coherence are balanced in such a manner that coherence of the entire heat transport process is realized. We also find that the heat current does not follow Fourier’s law when the temperature difference is very large, due to the non-perturbative system-bath interactions.

Description: Recent progress in electronic and electromagnetic topological insulators has led to the demonstration of one way propagation of electron and photon edge states and the possibility of immunity to backscattering by edge defects. Unfortunately, such topologically protected propagation of waves in the bulk of a material has not been observed. We show, in the case of sound/elastic waves, that bulk waves with unidirectional backscattering-immune topological states can be observed in a time-dependent elastic superlattice. The superlattice is realized via spatial and temporal modulation of the stiffness of an elastic material. Bulk elastic waves in this superlattice are supported by a manifold in momentum space with the topology of a single twist Möbius strip. Our results demonstrate the possibility of attaining one way transport and immunity to scattering of bulk elastic waves.

Description: Amorphous silicon enables the fabrication of very high-efficiency crystalline-silicon-based solar cells due to its combination of excellent passivation of the crystalline silicon surface and permeability to electrical charges. Yet, amongst other limitations, the passivation it provides degrades upon high-temperature processes, limiting possible post-deposition fabrication possibilities (e.g., forcing the use of low-temperature silver pastes). We investigate the potential use of intrinsic amorphous silicon carbide passivating layers to sidestep this issue. The passivation obtained using device-relevant stacks of intrinsic amorphous silicon carbide with various carbon contents and doped amorphous silicon are evaluated, and their stability upon annealing assessed, amorphous silicon carbide being shown to surpass amorphous silicon for temperatures above 300 °C. We demonstrate open-circuit voltage values over 700 mV for complete cells, and an improved temperature stability for the open-circuit voltage. Transport of electrons and holes across the hetero-interface is studied with complete cells having amorphous silicon carbide either on the hole-extracting side or on the electron-extracting side, and a better transport of holes than of electrons is shown. Also, due to slightly improved transparency, complete solar cells using an amorphous silicon carbide passivation layer on the hole-collecting side are demonstrated to show slightly better performances even prior to annealing than obtained with a standard amorphous silicon layer.

Description: The crack initiation and growth mechanisms in an 2D graphene lattice structure are studied based on molecular dynamics simulations. Crack growth in an initial edge crack model in the arm-chair and the zig-zag lattice configurations of graphene are considered. Influence of the time steps on the post yielding behaviour of graphene is studied. Based on the results, a time step of 0.1 fs is recommended for consistent and accurate simulation of crack propagation. Effect of temperature on the crack propagation in graphene is also studied, considering adiabatic and isothermal conditions. Total energy and stress fields are analyzed. A systematic study of the bond stretching and bond reorientation phenomena is performed, which shows that the crack propagates after significant bond elongation and rotation in graphene. Variation of the crack speed with the change in crack length is estimated.

Description: Transfer-free graphene synthesis was performed on sapphire substrates by using the catalyst metal agglomeration technique, and the graphene film quality was compared to that synthesized on sputtered SiO 2 /Si substrates. Raman scattering measurements indicated that the graphene film on sapphire has better structural qualities than that on sputtered SiO 2 /Si substrates. The cross-sectional transmission microscopic study also revealed that the film flatness was drastically improved by using sapphire substrates instead of sputtered SiO 2 /Si substrates. These quality improvements seemed to be due the chemical and thermal stabilities of sapphire. Top-gate field-effect transistors were fabricated using the graphene films on sapphire, and it was confirmed that their drain current can be modulated with applied gate voltages. The maximum field-effect mobilities were estimated to be 720 cm 2 /V s for electrons and 880 cm 2 /V s for holes, respectively.

Description: A series of Si-doped AlN-rich AlGaN layers with low resistivities was characterized by a combination of nanoscale imaging techniques. Utilizing the capability of scanning electron microscopy to reliably investigate the same sample area with different techniques, it was possible to determine the effect of doping concentration, defect distribution, and morphology on the luminescence properties of these layers. Cathodoluminescence shows that the dominant defect luminescence depends on the Si-doping concentration. For lower doped samples, the most intense peak was centered between 3.36 eV and 3.39 eV, while an additional, stronger peak appears at 3 eV for the highest doped sample. These peaks were attributed to the (V III -O N ) 2− complex and the V III 3 − vacancy, respectively. Multimode imaging using cathodoluminescence, secondary electrons, electron channeling contrast, and atomic force microscopy demonstrates that the luminescence intensity of these peaks is not homogeneously distributed but shows a strong dependence on the topography and on the distribution of screw dislocations.

Description: A wide variety of physical systems respond to changing external conditions through discrete impulsive events called jerks, typically leading to collective “crackling noise” behaviour. Statistical distributions of jerky events often exhibit a universal scale-invariant power law, regardless of the specific mechanisms that are responsible for crackling noise processes and microstructural features that affect them. Here, we analyse uniaxial compression loading curves of two different physical systems that exhibit jerky behaviour: a martensitic NiMnGa single crystal and a stack of corrugated fiberboards. The jerky response is attributed to a non-uniform twin boundary motion along the NiMnGa crystal and to a local buckling of individual fiberboard layers. In both cases, our analysis reveals that different variables exhibit different statistical distributions. While the velocity of temporal processes within jerky events exhibits scale invariant distribution, the irreversible displacements induced throughout complete events are distributed around a characteristic value. In the case of NiMnGa, the displacement of a twin boundary is directly related to the length-scale of the internal magneto-mechanical microstructure. Similarly, the displacement of the fiberboard stack corresponds to the thickness of individual board layers. These observations reveal the effect of the internal microstructure on crackling noise systems and demonstrate an analysis approach for uncovering the details of the jerk mechanism.

Description: by Andrew J. Massey High-content imaging is a powerful tool for determining cell phenotypes at the single cell level. Characterising the effect of small molecules on cell cycle distribution is important for understanding their mechanism of action especially in oncology drug discovery but also for understanding potential toxicology liabilities. Here, a high-throughput phenotypic assay utilising the PerkinElmer Operetta high-content imager and Harmony software to determine cell cycle distribution is described. PhenoLOGIC, a machine learning algorithm within Harmony software was employed to robustly separate single cells from cell clumps. DNA content, EdU incorporation and pHH3 (S10) expression levels were subsequently utilised to separate cells into the various phases of the cell cycle. The assay is amenable to multiplexing with an additional pharmacodynamic marker to assess cell cycle changes within a specific cellular sub-population. Using this approach, the cell cycle distribution of γH2AX positive nuclei was determined following treatment with DNA damaging agents. Likewise, the assay can be multiplexed with Ki67 to determine the fraction of quiescent cells and with BrdU dual labelling to determine S-phase duration. This methodology therefore provides a relatively cheap, quick and high-throughput phenotypic method for determining accurate cell cycle distribution for small molecule mechanism of action and drug toxicity studies.

Description: We performed density functional theory (DFT) calculations for a bi-layered heterostructure combining a graphene layer with a MoS 2 layer with and without intercalated Li atoms. Our calculations demonstrate the importance of the van der Waals (vdW) interaction, which is crucial for forming stable bonding between the layers. Our DFT calculation correctly reproduces the linear dispersion, or Dirac cone, feature at the Fermi energy for the isolated graphene monolayer and the band gap for the MoS 2 monolayer. For the combined graphene/MoS 2 bi-layer, we observe interesting electronic structure and density of states (DOS) characteristics near the Fermi energy, showing both the gap like features of the MoS 2 layer and in-gap states with linear dispersion contributed mostly by the graphene layer. Our calculated total DOS in this vdW heterostructure reveals that the graphene layer significantly contributes to pinning the Fermi energy at the center of the band gap of MoS 2 . We also find that intercalating Li ions in between the layers of the graphene/MoS 2 heterostructure enhances the binding energy through orbital hybridizations between cations (Li adatoms) and anions (graphene and MoS 2 monolayers). Moreover, we calculate the dielectric function of the Li intercalated graphene/MoS 2 heterostructure, the imaginary component of which can be directly compared with experimental measurements of optical conductivity in order to validate our theoretical prediction. We observe sharp features in the imaginary component of the dielectric function, which shows the presence of a Drude peak in the optical conductivity, and therefore metallicity in the lithiated graphene/MoS 2 heterostructure.

Description: Carrier injection from Au electrodes to organic thin-film active layers can be greatly improved for both electrons and holes by nano-structural surface control of organic semiconducting thin films using long-chain aliphatic molecules on a SiO 2 gate insulator. In this paper, we demonstrate a stark contrast for a 2,5-bis(4-biphenylyl)bithiophene (BP2T) active semiconducting layer grown on a modified SiO 2 dielectric gate insulator between two different modifications of tetratetracontane and poly(methyl methacrylate) thin films. Important evidence that the field effect transistor (FET) characteristics are independent of electrode metals with different work functions is given by the observation of a conversion of the metal-semiconductor contact from the Schottky limit to the Bardeen limit. An air-stable light emitting FET with an Au electrode is demonstrated.

Description: Femtosecond optical pump-probe spectroscopy is used to reveal the influence of charge and magnetic order on polaron dynamics and coherent acoustic phonon oscillations in single crystals of charge-ordered, ferrimagnetic LuFe 2 O 4 . We experimentally observed the influence of magnetic order on polaron dynamics. We also observed a correlation between charge order and the amplitude of the acoustic phonon oscillations, due to photoinduced changes in the lattice constant that originate from the photoexcited electrons. This provides insight into the general behavior of coherent acoustic phonon oscillations in charge-ordered materials.

Description: In this work, we explore the hardening mechanisms in WB 4 -based solid solutions upon addition of Ta, Mn, and Cr using in situ radial X-ray diffraction techniques under non-hydrostatic pressure. By examining the lattice-supported differential strain, we provide insights into the mechanism for hardness increase in binary solid solutions at low dopant concentrations. Speculations on the combined effects of electronic structure and atomic size in ternary WB 4 solid solutions containing Ta with Mn or Cr are also included to understand the extremely high hardness of these materials.

Description: Semiconductor fabrication often requires the deposition of hydrogenated silicon nitride (SiN x H y ) film using SiH 4 /NH 3 /N 2 /He capacitively coupled plasma (CCP) discharge. As analysis of the discharge geometry is essential to understanding CCP deposition, the effect of electrode spacing on the two-dimensional distributions of electrons, ions, and metastable and radical molecules was analyzed numerically using a fluid model. The simulation shows that the spatial variations in the ionization rates near the sheath become more obvious as the electrode spacing increases. In addition, as molecule-molecule gas-phase reactions are significantly affected by the local residence time, large electrode spacings are associated with significant volumetric losses for positive ions. Consequently, an increase of the electrode spacing leads axial density profiles of ions to change from bell shaped to double humped. However, NH 4 + persistently maintains a bell-shaped axial density profile regardless of the degree of electrode spacing. We set the mole fraction of NH 3 to only 1% of the total flow at the inlet, but NH 4 + is the most abundant positive ion at the large electrode spacings. As the gas flow can transport the radicals around the space between the electrodes, we found that radical density distribution shifts toward the grounded electrode. The shift becomes pronounced as the electrode spacing increases. Finally, to validate our model, we compared the calculated deposition rate profile with the experimental data obtained along the wafer radius. According to our numerical results, the SiN x H y deposition rate decreases by approximately 16% when the electrode spacing increases from 9 to 20 mm.

Description: We have evaluated tunnel barriers formed in multi-walled carbon nanotubes (MWNTs) by an Ar atom beam irradiation method and applied the technique to fabricate coupled double quantum dots. The two-terminal resistance of the individual MWNTs was increased owing to local damage caused by the Ar beam irradiation. The temperature dependence of the current through a single barrier suggested two different contributions to its Arrhenius plot, i.e., formed by direct tunneling through the barrier and by thermal activation over the barrier. The height of the formed barriers was estimated. The fabrication technique was used to produce coupled double quantum dots with serially formed triple barriers on a MWNT. The current measured at 1.5 K as a function of two side-gate voltages resulted in a honeycomb-like charge stability diagram, which confirmed the formation of the double dots. The characteristic parameters of the double quantum dots were calculated, and the feasibility of the technique is discussed.

Description: Previous studies on magnetic flux expulsion as a function of cooldown procedures for elliptical superconducting radio frequency (SRF) niobium cavities showed that when the cavity beam axis is placed parallel to the helium cooling flow and sufficiently large thermal gradients are achieved, all magnetic flux could be expelled and very low residual resistance could be achieved. In this paper, we investigate flux trapping for the case of resonators positioned perpendicularly to the helium cooling flow, which is more representative of how SRF cavities are cooled in accelerators and for different directions of the applied magnetic field surrounding the resonator. We show that different field components have a different impact on the surface resistance, and several parameters have to be considered to fully understand the flux dynamics. A newly discovered phenomenon of concentration of flux lines at the cavity top leading to temperature rise at the cavity equator is presented.

Description: Detailed magnetically tunable ac electrical properties of x La 0.7 Sr 0.3 MnO 3 (LSMO)–(1 − x) ErMnO 3 (EMO) (x = 0.1, 0.3, and 0.5) multiferroic nanocomposites have been studied at 300 K in presence of varying magnetic field (H appl ), applied both in parallel and perpendicular configuration with respect to the measuring electric field. AC electrical properties have exhibited significant variation with H appl for all composites, whereas for parallel configuration of H appl such effect is very feeble for x = 0.3 composite. We have attributed this anisotropic behavior to the demagnetization effect in the sample. In contrast, for x = 0.1 and 0.5 composites, no such anisotropy effect is experimentally evidenced. Impedance and real part of impedance have been found to decrease with H appl at low frequency ( f ) region. We attribute this observation to the depinning of the magnetic domain walls from the grain boundaries pinning centers and thereby enhancing the spin dependent transport in the composite. For x = 0.3 composite, Nyquist plots have been fitted considering dominant contributions of LSMO and EMO grain boundaries and the interface region between them. However, for x = 0.1 composite, it corresponds to EMO grain boundaries and grain boundary interface region. The relaxation frequency ( f R ) is observed to shift at higher/lower f region in perpendicular/parallel configuration of H appl for x = 0.3 composite. This opposite variation of f R s with H appl for perpendicular and parallel configurations has been attributed to two competing factors of H appl induced enhancement of inductive part and H appl enhanced spin dependent transport causing fast relaxation processes in the sample. For x = 0.1 composite, in both configurations of H appl , f R s is shifting towards high f region, which has been discussed in terms of dominant role of spin dependent transport.

Description: A new high quality potential energy surface is calculated at a coupled-cluster single double triple level with an aug-cc-pV5Z basis set for the HCS + –He system. This potential energy surface is used in low energy quantum scattering calculations to provide a set of (de)-excitation cross sections and rate coefficients among the first 20 rotational levels of HCS + by He in the range of temperature from 5 K to 100 K. The paper discusses the impact of the new ab initio potential energy surface on the cross sections at low energy and provides a comparison with the HCO + –He system. The HCS + –He rate coefficients for the strongest transitions differ by factors of up to 2.5 from previous rate coefficients; thus, analysis of astrophysical spectra should be reconsidered with the new rate coefficients.

Description: A weak, paradoxically narrow resonance feature (shortly, the r -line) near the O 2 fundamental frequency in the collision-induced absorption spectrum of oxygen dissolved in liquid argon and liquid nitrogen ( T = 89 K) is resolved for the first time. An accurate band shape fitting routine to separate the r -line from the by-far more intense diffuse background and to study its behavior versus the oxygen mole fraction x which ranged from 0.03 up to 0.23 has been elaborated. At small x (≲0.07), the r -line intensity was found to scale as x 2 leaving no doubt that it is due to the solute-solute (O 2 –O 2 ) interactions. In line with our results on the p H 2 –LNe cryosystem [Herrebout, Phys. Rev. Lett. 101 , 093001 (2008)], the Lorentzian r -line shape and its extraordinary sharpness (half width at half height ≈ 1 cm −1 ) are indicative of the motional narrowing of the relative solute-solute translational spectrum. As x is further raised, ternary solute-solute interactions impede the r -line growth in the O 2 –LAr spectrum because of the cancellation effect [J. Van Kranendonk, Physica 23 , 825 (1957)]. Theoretical arguments are given that multiple interactions between the solutes should finally destroy the solute-solute induced r -line when the mixed solution approaches the limit of the pure liquid ( x = 1). Interestingly, the nonbinary effects are too weak to appreciably affect the quadratic r -line scaling in the O 2 –LN 2 cryosystem which persists up to x = 0.23. It is emphasized that studies of the resonant features in the collision-induced spectra of binary cryosolutions open up unique opportunities to spectroscopically trace the microscopic-scale diffusion.

Description: Three-body and higher intermolecular interactions can play an important role in molecular condensed phases. Recent benchmark calculations found problematic behavior for many widely used density functional approximations in treating 3-body intermolecular interactions. Here, we demonstrate that the combination of second-order Møller-Plesset (MP2) perturbation theory plus short-range damped Axilrod-Teller-Muto (ATM) dispersion accurately describes 3-body interactions with reasonable computational cost. The empirical damping function used in the ATM dispersion term compensates both for the absence of higher-order dispersion contributions beyond the triple-dipole ATM term and non-additive short-range exchange terms which arise in third-order perturbation theory and beyond. Empirical damping enables this simple model to out-perform a non-expanded coupled Kohn-Sham dispersion correction for 3-body intermolecular dispersion. The MP2 plus ATM dispersion model approaches the accuracy of O ( N 6 ) methods like MP2.5 or even spin-component-scaled coupled cluster models for 3-body intermolecular interactions with only O ( N 5 ) computational cost.

Description: A first sharp diffraction peak (FSDP) is observed in the X-ray total structure factor of a molten mixture of RbCl-AgCl, while both pure melts of RbCl and AgCl do not exhibit FSDP individually. Molecular dynamics simulations were performed to investigate the origin of the FSDP with the polarizable ion model (PIM). Coexistence of covalent Ag–Cl and ionic Rb–Cl bonds leads the system to evolve intermediate range ordering, which is simulated by introducing the induced polarization in different ways between Ag–Cl with fully polarizable treatment based on Vashishta-Raman potential and Rb–Cl with suppression over-polarization in the nearest neighbor contribution based on Born-Meyer potential. The partial structure factors for both the Ag–Ag and Rb–Rb correlations, S AgAg ( Q ) and S RbRb ( Q ), show a positive contribution to the FSDP, while S AgRb ( Q ) for the Ag–Rb correlation exhibits a negative contribution, indicating that Ag and Rb ions are distributed in an alternating manner within the intermediate-range length scale. The origin of the intermediate-range chemical ordering of cations can be ascribed to the preferred direction of the dipole moments of anions in the PIM.

Description: The recently developed density matrix quantum Monte Carlo (DMQMC) algorithm stochastically samples the N -body thermal density matrix and hence provides access to exact properties of many-particle quantum systems at arbitrary temperatures. We demonstrate that moving to the interaction picture provides substantial benefits when applying DMQMC to interacting fermions. In this first study, we focus on a system of much recent interest: the uniform electron gas in the warm dense regime. The basis set incompleteness error at finite temperature is investigated and extrapolated via a simple Monte Carlo sampling procedure. Finally, we provide benchmark calculations for a four-electron system, comparing our results to previous work where possible.

Description: Despite the fundamental importance of electron density in density functional theory, perturbations are still usually dealt with using Hartree-Fock-like orbital equations known as coupled-perturbed Kohn-Sham (CPKS). As an alternative, we develop a perturbation theory that solves for the perturbed density directly, removing the need for CPKS. This replaces CPKS with a true Hohenberg-Kohn density perturbation theory. In CPKS, the perturbed density is found in the basis of products of occupied and virtual orbitals, which becomes ever more over-complete as the size of the orbital basis set increases. In our method, the perturbation to the density is expanded in terms of a series of density basis functions and found directly. It is possible to solve for the density in such a way that it makes the total energy stationary even if the density basis is incomplete.

Description: We have developed a multi-agent quantum Monte Carlo model to describe the spatial dynamics of multiple majority charge carriers during conduction of electric current in the channel of organic field-effect transistors. The charge carriers are treated by a neglect of diatomic differential overlap Hamiltonian using a lattice of hydrogen-like basis functions. The local ionization energy and local electron affinity defined previously map the bulk structure of the transistor channel to external potentials for the simulations of electron- and hole-conduction, respectively. The model is designed without a specific charge-transport mechanism like hopping- or band-transport in mind and does not arbitrarily localize charge. An electrode model allows dynamic injection and depletion of charge carriers according to source-drain voltage. The field-effect is modeled by using the source-gate voltage in a Metropolis-like acceptance criterion. Although the current cannot be calculated because the simulations have no time axis, using the number of Monte Carlo moves as pseudo-time gives results that resemble experimental I/V curves.

Description: The characteristic properties of graphene make it useful in an assortment of applications. One particular application—the use of graphene in biosensors—requires a thorough understanding of graphene-peptide interactions. In this study, the binding of glycine (G) capped amino acid residues (termed GXG tripeptides) to trilayer graphene surfaces in aqueous solution was examined and compared to results previously obtained for peptide binding to single-layer free-standing graphene [A. N. Camden, S. A. Barr, and R. J. Berry, J. Phys. Chem. B 117 , 10691–10697 (2013)]. In order to understand the interactions between the peptides and the surface, binding enthalpy and free energy values were calculated for each GXG system, where X cycled through the typical 20 amino acids. When the GXG tripeptides were bound to the surface, distinct conformations were observed, each with a different binding enthalpy. Analysis of the binding energy showed the binding of peptides to trilayer graphene was dominated by van der Waals interactions, unlike the free-standing graphene systems, where the binding was predominantly electrostatic in nature. These results demonstrate the utility of computational materials science in the mechanistic explanation of surface-biomolecule interactions which could be applied to a wide range of systems.

Description: by Stéphane J. Montuelle, Susan H. Williams Cranial kinesis refers to movements of skeletal sub-units relative to one another at mobile sutures within the skull. The presence and functional significance of cranial kinesis has been investigated in various vertebrates, with much of our understanding coming from comparative studies and manipulation of ligamentous specimens. Drawing on these studies, cranial kinesis in lizards has been modeled as a four-bar linkage system involving streptostyly (rotation of the quadrate), hypokinesis (dorsoventral flexion and extension of the palato-maxillary sub-unit), mesokinesis (dorsoventral flexion and extension of the snout at the fronto-parietal suture) and metakinesis (sliding movements between parietal and supraocciptal bones). In vivo studies, although limited, suggest that cranial kinesis serves an important role during routine behaviors such as feeding. Here, we use X-ray Reconstruction Of Moving Morphology to further quantify mesokinesis in vivo in Gekko gecko during three routine behaviors: gape display, biting and post-ingestion feeding. During gape display, the snout rotates dorsally above rest position, with mesokinesis accounting for a 10% increase in maximum gape over that achieved solely by the depression of the lower jaw. During defensive biting, the snout rotates ventrally below rest position to participate in gape closure. Finally, ventroflexion of the snout also occurs during post-ingestion feeding, accounting for 42% of gape closure during intra-oral transport, 86% during puncture-crushing, and 61% during pharyngeal packing. Mesokinesis thus appears to facilitate prey puncturing by allowing the snout to rotate ventrally so that the upper teeth pierce the prey item, thus limiting the need for large movements of the lower jaw. This is suggested to maintain a firm grip on the prey and reduce the possibility of prey escape. More generally, this study demonstrates that mesokinesis is a key component of defensive biting and gape display behaviors, as well as post-ingestion feeding, all of which are linked to organismal fitness.

Description: by Xianqiong Gong, Jiaen Yang, Jinmo Tang, Chong Gu, Lijian Huang, Ying Zheng, Huiqing Liang, Min Wang, Chuncheng Wu, Yue Chen, Manying Zhang, Zhijian Yu, Qianguo Mao To understand the mechanisms underlying the discordance between normal serum alanine aminotransferase (ALT) levels and significant alterations in liver histology of chronic hepatitis B virus (HBV) infection with persistent normal ALT (PNALT) or minimally elevated ALT. A total of 300 treatment-naive chronic HBV-infected patients with PNALT (ALT ≤ upper limit of normal [ULN, 40 U/ml]) or minimally elevated ALT (1-2×ULN) were retrospectively enrolled. All patients underwent liver biopsy and histological changes were analyzed along with biochemical and HBV markers. Among 300 participants, 177 were HBeAg-positive and 123 HBeAg-negative. Significant histologic abnormalities were found in 42.9% (76/177) and 52.8% (65/123) of HBeAg-positive and HBeAg-negative patients, respectively. Significant fibrosis, which is a marker of prior injury, was more frequently detected than significant necroinflammation (suggesting active liver injury) in both HBeAg-positive and -negative groups, suggesting that liver injury occurred intermittently in our cohort. No significant differences were noticed in the percentage of patients with severe fibrosis between HBeAg-positive and negative phases or between ages 30 and 40 and over 40, suggesting that the fibrosis was possibly carried over from an early phase. Finally, lowering ALT ULN (30 U/L for men, 19 U/L for women) alone was not adequate to increase the sensitivity of ALT detection of liver injury. However, the study was limited to a small sample size of 13 HBeAg-positive patients with ALT in the revised normal range. We detected significant liver pathology in almost 50% of chronic HBV infected patients with PNALT (ALT ≤ 40 U/ml) or minimally elevated ALT. We postulated that small-scale intermittent liver injury was possibly responsible for the discordance between normal serum ALT and significant liver changes in our cohort.

Description: A class of real spectral triples that are similar in structure to a Riemannian manifold but have a finite-dimensional Hilbert space is defined and investigated, determining a general form for the Dirac operator. Examples include fuzzy spaces defined as real spectral triples. Fuzzy 2-spheres are investigated in detail, and it is shown that the fuzzy analogues correspond to two spinor fields on the commutative sphere. In some cases, it is necessary to add a mass mixing matrix to the commutative Dirac operator to get a precise agreement for the eigenvalues.

Description: Scanning nano-focused X-ray diffraction and high-angle annular dark-field scanning transmission electron microscopy are used to investigate the crystal structure of ramp-edge junctions between superconducting electron-doped Nd 1.85 Ce 0.15 CuO 4 and superconducting hole-doped La 1.85 Sr 0.15 CuO 4 thin films, the latter being the top layer. On the ramp, a new growth mode of La 1.85 Sr 0.15 CuO 4 with a 3.3° tilt of the c -axis is found. We explain the tilt by developing a strain accommodation model that relies on facet matching, dictated by the ramp angle, indicating that a coherent domain boundary is formed at the interface. The possible implications of this growth mode for the creation of artificial domains in morphotropic materials are discussed.

Description: We propose a tunable metasurface consisting of an array of graphene ribbons on a silver mirror with a SiO 2 gap layer to control reflected wavefront at terahertz frequencies. The graphene ribbons exhibit localized plasmon resonances depending on their Fermi levels to introduce abrupt phase shifts along the metasurface. With interference of the Fabry-Perot resonances in the SiO 2 layer, phase shift through the system is largely accumulated, covering the 0-to-2π range for full control of the wavefront. Numerical simulations prove that wide-angle beam steering up to 53° with a high reflection efficiency of 60% is achieved at 5 THz within a switching time shorter than 0.6 ps.

Description: We introduce a transparent diode that shows both high rectifying ratio and low leakage current at process temperature below 250 °C. This device is clearly distinguished from all previous transparent diodes in that the rectifying behavior results from the junction between a semiconductor (amorphous indium-gallium-zinc oxide (a-IGZO)) and insulator (SiN x ). We systematically study the properties of each junction within the device structure and demonstrate that the a-IGZO/SiN x junction is the source of the outstanding rectification. The electrical characteristics of this transparent diode are: 2.8 A/cm 2 on-current density measured at −7 V; lower than 7.3 × 10 −9 A/cm 2 off-current density; 2.53 ideality factor; and high rectifying ratio of 10 8 –10 9 . Furthermore, the diode structure has a transmittance of over 80% across the visible light range. The operating principle of the indium-tin oxide (ITO)/a-IGZO/SiN x /ITO device was examined with an aid of the energy band diagram and we propose a preliminary model for the rectifying behavior. Finally, we suggest further directions for research on this transparent diode.

Description: Relaxation mechanisms in polyaniline (PANI)/Reduced Graphene Oxide (RGO) nanocomposites are investigated using broad band dielectric spectroscopy. The multilayered nanostructural features of the composites and the intimate interactions between PANI and RGO are evidenced by field emission scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy. Increasing the RGO fraction in the composites results in a relaxation process observed at a frequency of ca. 5 kHz. This mechanism is associated with an electrical charge trapping phenomenon occurring at the PANI/RGO interfaces. The dielectric relaxation processes are interpreted according to the Sillars approach and the results are consistent with the presence of conducting prolate spheroids (RGO) embedded into a polymeric matrix (PANI). Dielectric permittivity data are analyzed within the framework of the Kohlrausch-William-Watts model, evidencing a Debye-like relaxation process.

Description: The lattice strain and domain switching behavior of x BiScO 3 –(1- x )PbTiO 3 ( x  = 0.40) was investigated as a function of cyclic field and grain orientation by in situ X-ray diffraction during application of electric fields. The electric field induced 200 lattice strain was measured to be five times larger than the 111 lattice strain in pseudorhombohedral x BiScO 3 –(1- x )PbTiO 3 ( x  = 0.40). It is shown that the anomalous 200 lattice strain is not an intrinsic phenomenon, but arises primarily due to stress associated with the reorientation of the 111 domains in dense polycrystalline ceramic.

Description: We present a comparative study of high frequency dynamics and low frequency noise in elliptical magnetic tunnel junctions with lateral dimensions under 100 nm presenting current-switching phenomena. The analysis of the high frequency oscillation modes with respect to the current reveals the onset of a steady-state precession regime for negative bias currents above J = 10 7 A / cm 2 , when the magnetic field is applied along the easy axis of magnetization. By the study of low frequency noise for the same samples, we demonstrate the direct link between changes in the oscillation modes with the applied current and the normalised low frequency (1/f) noise as a function of the bias current. These findings prove that low frequency noise studies could be a simple and powerful technique to investigate spin-torque based magnetization dynamics.

Description: Copper is a harmful metal impurity that significantly impacts the performance of silicon-based devices if present in active regions. In this contribution, we propose a fast method consisting of simultaneous illumination and annealing for the detection of copper contamination in p-type silicon. Our results show that, within minutes, such method is capable of producing a significant reduction of the minority carrier lifetime. A spatial distribution map of copper contamination can then be obtained through the lifetime values measured before and after degradation. In order to separate the effect of the light-activated copper defects from the other metastable complexes in low resistivity Cz-silicon, we carried out a dark anneal at 200 °C, which is known to fully recover the boron-oxygen defect. Similar to the boron-oxygen behavior, we show that the dark anneal also recovers the copper defects. However, the recovery is only partial and it can be used to identify the possible presence of copper contamination.