bluuebunny/crossref_metadata_2025 huggingface dataset:
Polarization conversion system with liquid-crystal geometric-phase-based cylindrical lens
Authors: Honma Michinori , Nose Toshiaki
Published: December 2015

We demonstrate a polarization conversion system by utilizing the polarization-splitting function of a liquid-crystal (LC) geometric-phase-based cylindrical lens. The system was constructed by combining the LC lens with a partially rubbed cell. The operation principle includes the following two steps. (i) The incident light is first decomposed into right- and left-handed circularly polarized light (RCP and LCP, respectively) as an attribute of geometric-phase-based optical elements. (ii) Then, only the RCP light is transformed into LCP light by passing it through the partially rubbed cell; as a result, the incident unpolarized light is converted into LCP light. We experimentally reveal the feasibility of the system by evaluating the effects, on the polarization conversion capability, of the diffraction efficiency, focal length, and partially rubbed cell’s retardation. The polarization conversion efficiency was obtained to be 65% on average for 400–700 nm and a maximum of 79% at 610 nm.
Suppression of sound radiation to far field of near-field acoustic communication system using evanescent sound field
Authors: Fujii Ayaka , Wakatsuki Naoto , Mizutani Koichi
Published: December 2015

A method of suppressing sound radiation to the far field of a near-field acoustic communication system using an evanescent sound field is proposed. The amplitude of the evanescent sound field generated from an infinite vibrating plate attenuates exponentially with increasing a distance from the surface of the vibrating plate. However, a discontinuity of the sound field exists at the edge of the finite vibrating plate in practice, which broadens the wavenumber spectrum. A sound wave radiates over the evanescent sound field because of broadening of the wavenumber spectrum. Therefore, we calculated the optimum distribution of the particle velocity on the vibrating plate to reduce the broadening of the wavenumber spectrum. We focused on a window function that is utilized in the field of signal analysis for reducing the broadening of the frequency spectrum. The optimization calculation is necessary for the design of window function suitable for suppressing sound radiation and securing a spatial area for data communication. In addition, a wide frequency bandwidth is required to increase the data transmission speed. Therefore, we investigated a suitable method for calculating the sound pressure level at the far field to confirm the variation of the distribution of sound pressure level determined on the basis of the window shape and frequency. The distribution of the sound pressure level at a finite distance was in good agreement with that obtained at an infinite far field under the condition generating the evanescent sound field. Consequently, the window function was optimized by the method used to calculate the distribution of the sound pressure level at an infinite far field using the wavenumber spectrum on the vibrating plate. According to the result of comparing the distributions of the sound pressure level in the cases with and without the window function, it was confirmed that the area whose sound pressure level was reduced from the maximum level to −50 dB was extended. Additionally, we designed a sound insulator so as to realize a similar distribution of the particle velocity to that obtained using the optimized window function. Sound radiation was suppressed using a sound insulator put above the vibrating surface in the simulation using the three-dimensional finite element method. On the basis of this finding, it was suggested that near-field acoustic communication which suppressed sound radiation can be realized by applying the optimized window function to the particle velocity field.
Formation of diamond-like carbon thin films using barrier-type surface discharge plasma under atmospheric pressure
Authors: Yasui Shinji , Tada Kazuya , Takuwa Tetsuya
Published: December 2015

We studied the deposition of diamond-like carbon (DLC) thin films using barrier-type surface discharge plasma under atmospheric pressure. The main radicals generated by the barrier-type surface discharge using H2, CH4, and He as the plasma gases were Hα, Hβ, and CH. The emission intensities increased as the ratio of CH4 in the mixed gas decreased, and the mixed gas ratios of 2% CH4, 18% H2, 80% He were appropriate for the generation of the barrier-type surface discharge. The gas flow rate and applied voltage required to achieve a suitable plasma state for deposition of the DLC films varied depending on the polarity of the applied pulse. When a negative pulse is used, homogenous films can be obtained on the silicon wafer under the entire hole of the electrode; however, the deposition rate becomes very low in the range of 1.8–5.8 nm/min because the surface streamer plasma is very weak. On the other hand, using a bipolar and a positive pulse, a relatively high deposition rate in the range of 10–30 nm/min can be achieved on the silicon wafer under the central part of the electrode, although the thickness of the DLC films becomes nonuniform at the edge part of the electrode. The appropriate conditions of the DLC film deposition in this study were the pulse voltages of 6–8 kV and a gas flow rate of 1500 mL/min when using bipolar- and positive-pulse voltages. The relatively hard DLC films (6–8 GPa) were obtained under these conditions.
Control of hydrogen and carbon impurity inclusion during the growth of GaAsN thin film by atomic layer epitaxy
Authors: Yokoyama Yuki , Fukuyama Atsuhiko , Haraguchi Tomohiro , Yamauchi Toshihiro , Ikari Tetsuo , Suzuki Hidetoshi
Published: December 2015

The effects of growth temperature and nitrogen (N) source duration on N, carbon (C), and hydrogen (H) concentrations in GaAsN layers grown by atomic layer epitaxy (ALE) were investigated to understand the incorporation mechanisms of these atoms. In addition, the effects of the above growth conditions on the self-limiting mechanism (SLM) were investigated. The SLM was in effect at growth temperatures of 500 and 520 °C. The origin of the residual C was not N but other sources. With increasing N source duration, the N and H concentrations increased and saturated. The N incorporation mechanisms were discussed by a simple model considering the absorption and desorption of N atoms on the gallium (Ga)-covered surface. H atoms originating from the N source were incorporated in to the GaAsN layer. According to the ratio of the H concentration to the N concentration, the difference in the incorporation processes of N and H atoms in ALE-grown GaAsN layers was discussed.
Formation and characterization of high-density FeSi nanodots on SiO2 induced by remote H2 plasma
Authors: Zhang Hai , Makihara Katsunori , Ohta Akio , Ikeda Mitsuhisa , Miyazaki Seiichi
Published: December 2015

We demonstrated the formation of high-density iron silicide nanodots (NDs) on thermally grown SiO2 by exposing an electron-beam-evaporated Fe/amorphous-Si/Fe (Fe/a-Si/Fe) trilayer stack to remote H2 plasma without any external heating and characterized their silicidation state and crystalline phase. After the remote H2 plasma exposure, the formation of NDs with an areal density of ∼4.3 × 1011 cm−2 and an average height of ∼7.1 nm was confirmed. X-ray photoelectron spectroscopy (XPS) analyses indicate silicidation reaction induced by the remote H2 plasma exposure, which was accompanied by the agglomeration of Fe and Si atoms on the SiO2 surface. The formation of a crystalline β-FeSi2 phase was confirmed by Raman scattering spectroscopy and XRD pattern measurements. The electrical separation among the β-FeSi2 NDs was confirmed from changes in surface potential due to charging of the dots. The surface potential of the NDs changed in a stepwise manner with respect to the tip voltage because of multistep electron injection into and extraction from the semiconductor β-FeSi2 NDs.
Leionema lamprophyllum subsp. fractum (Rutaceae); a new and highly restricted taxon from the Hunter Valley of New South Wales
Authors: Bell Stephen A.J. , Walsh Neville G.
Published: December 2015

A new subspecies of Leionema lamprophyllum, formerly included in L. lamprophyllum subsp. obovatum F.M.Anderson, is here described as new. Currently known from fewer than 50 individuals, the new subsp. is highly restricted and warrants a conservation risk code of at least Endangered. An illustration of the new taxon, notes on its distribution and habitat, and a key to all four subspecies of L. lamprophyllum are also provided.
Commelina badamica (Commelinaceae), a new species from India
Authors: Nandikar Mayur D. , Gurav Rajaram V
Published: December 2015

A new species, Commelina badamica from the sandstone plateaus of Badami, Karnataka, India is described and illustrated. C. badamica is similar to C. clavata and C. diffusa, but differs in indefinite habit; linear–narrowly lanceolate leaves; puberulous or velutinous to tomentose spathes; clawless petals; velutinous ovary; radiately tri-lobed stigma; one capsule per spathe and trapezoidal, ventrally truncate seeds.
Electromagnetic Waves in Biaxially Anisotropic Media
Authors: Graham Jennifer W. , Lee Jay Kyoon
Published: December 2015

The article presents an overview of the wave behavior, governing equations, and some applications of biaxially anisotropic media. As this area of research matures, the governing behaviors described here will be of utmost importance to the understanding of device behavior. The biaxial nature of some manmade materials will be of increasing interest as we continue to manufacture materials to achieve unique electromagnetic behavior (metamaterials) and as the speed of communications increases over transmission lines on existing fabricated materials. This article is a review and a guide to the unique behavior of electromagnetic waves in biaxially anisotropic media.
Seismic velocity structure of the crust and shallow mantle of the Central and Eastern United States by seismic surface wave imaging
Authors: Pollitz Fred F. , Mooney Walter D.
Published: December 2015

Seismic surface waves from the Transportable Array of EarthScope's USArray are used to estimate phase velocity structure of 18 to 125 s Rayleigh waves, then inverted to obtain three‐dimensional crust and upper mantle structure of the Central and Eastern United States (CEUS) down to ∼200 km. The obtained lithosphere structure confirms previously imaged CEUS features, e.g., the low seismic‐velocity signature of the Cambrian Reelfoot Rift and the very low velocity at >150 km depth below an Eocene volcanic center in northwestern Virginia. New features include high‐velocity mantle stretching from the Archean Superior Craton well into the Proterozoic terranes and deep low‐velocity zones in central Texas (associated with the late Cretaceous Travis and Uvalde volcanic fields) and beneath the South Georgia Rift (which contains Jurassic basalts). Hot spot tracks may be associated with several imaged low‐velocity zones, particularly those close to the former rifted Laurentia margin.
Modification of the lower ionospheric conductivity by thunderstorm electrostatic fields
Authors: Salem Mohammad A. , Liu Ningyu , Rassoul Hamid K.
Published: December 2015

This paper reports a modeling study of the modifications of the nighttime lower ionospheric conductivity by electrostatic fields produced by underlying thunderstorms. The model used combines Ohm's law with a simplified lower ionospheric ion chemistry model to self‐consistently calculate the steady state nighttime conductivity above a thunderstorm. The results indicate that although the electron density is generally increased, the lower ionospheric conductivity can be reduced by up to 1–2 orders of magnitude because electron mobility is significantly reduced due to the electron heating effect. For a typical ionospheric density profile, the resulting changes in the reflection heights of extremely low frequency and very low frequency waves are 5 and 2 km, respectively.
Kinetic Alfvén turbulence below and above ion cyclotron frequency
Authors: Zhao J. S. , Voitenko Y. M. , Wu D. J. , Yu M. Y.
Published: December 2015

Alfvénic turbulent cascade perpendicular and parallel to the background magnetic field is studied accounting for anisotropic dispersive effects and turbulent intermittency. The perpendicular dispersion and intermittency make the perpendicular‐wave‐number magnetic spectra steeper and speed up production of high ion cyclotron frequencies by the turbulent cascade. On the contrary, the parallel dispersion makes the spectra flatter and decelerate the frequency cascade above the ion cyclotron frequency. Competition of these factors results in spectral indices distributed in the interval [−2, −3], where −2 is the index of high‐frequency space‐filling turbulence and −3 is the index of low‐frequency intermittent turbulence formed by tube‐like fluctuations. Spectra of fully intermittent turbulence fill a narrower range of spectral indices [−7/3, −3], which almost coincides with the range of indexes measured in the solar wind. This suggests that the kinetic‐scale turbulent spectra are mainly shaped by the dispersion and intermittency. A small mismatch with measured indexes of about 0.1 can be associated with damping effects not studied here.
Basin‐scale assessment of the land surface energy budget in the National Centers for Environmental Prediction operational and research NLDAS‐2 systems
Authors: Xia Youlong , Cosgrove Brian A. , Mitchell Kenneth E. , Peters‐Lidard Christa D. , Ek Michael B. , Kumar Sujay , Mocko David , Wei Helin
Published: December 2015

This paper compares the annual and monthly components of the simulated energy budget from the North American Land Data Assimilation System phase 2 (NLDAS‐2) with reference products over the domains of the 12 River Forecast Centers (RFCs) of the continental United States (CONUS). The simulations are calculated from both operational and research versions of NLDAS‐2. The reference radiation components are obtained from the National Aeronautics and Space Administration Surface Radiation Budget product. The reference sensible and latent heat fluxes are obtained from a multitree ensemble method applied to gridded FLUXNET data from the Max Planck Institute, Germany. As these references are obtained from different data sources, they cannot fully close the energy budget, although the range of closure error is less than 15% for mean annual results. The analysis here demonstrates the usefulness of basin‐scale surface energy budget analysis for evaluating model skill and deficiencies. The operational (i.e., Noah, Mosaic, and VIC) and research (i.e., Noah‐I and VIC4.0.5) NLDAS‐2 land surface models exhibit similarities and differences in depicting basin‐averaged energy components. For example, the energy components of the five models have similar seasonal cycles, but with different magnitudes. Generally, Noah and VIC overestimate (underestimate) sensible (latent) heat flux over several RFCs of the eastern CONUS. In contrast, Mosaic underestimates (overestimates) sensible (latent) heat flux over almost all 12 RFCs. The research Noah‐I and VIC4.0.5 versions show moderate‐to‐large improvements (basin and model dependent) relative to their operational versions, which indicates likely pathways for future improvements in the operational NLDAS‐2 system.
Air quality forecasting for winter‐time PM2.5 episodes occurring in multiple cities in central and southern Chile
Authors: Saide Pablo E. , Mena‐Carrasco Marcelo , Tolvett Sebastian , Hernandez Pablo , Carmichael Gregory R.
Published: December 2015

Episodic air quality degradation due to particles occurs in multiple cities in central and southern Chile during the austral winter reaching levels up to 300–800 µg/m3 hourly PM2.5, which can be associated with severe effects on human health. An air quality prediction system is developed to predict such events in near real time up to 3 days in advance for nine cities with regular air quality monitoring: Santiago, Rancagua, Curicó, Talca, Chillan, Los Ángeles, Temuco, Valdivia, and Osorno. The system uses the Weather Research and Forecasting with Chemistry model configured with a nested 2 km grid‐spacing domain to predict weather and inert tracers. The tracers are converted to hourly PM2.5 concentrations using an observationally based calibration which is substantially less computationally intensive than a full chemistry model. The conversion takes into account processes occurring in these cities, including higher likelihood of episode occurrence during weekends and during colder days, the latter related to increased wood‐burning‐stove activity for heating. The system is calibrated and evaluated for April–August 2014 where it has an overall skill of 53–72% of episodes accurately forecasted (61–76% for the best initialization) which is better than persistence for most stations. Forecasts one, two, and three days in advance all have skill in forecasting events but often present large variability within them due to different meteorological initializations. The system is being implemented in Chile to assist authority decisions not only to warn the population but also to take contingency‐based emission restrictions to try to avoid severe pollution events.
Dimension reduction of decision variables for multireservoir operation: A spectral optimization model
Authors: Chen Duan , Leon Arturo S. , Gibson Nathan L. , Hosseini Parnian
Published: December 2015

Optimizing the operation of a multireservoir system is challenging due to the high dimension of the decision variables that lead to a large and complex search space. A spectral optimization model (SOM), which transforms the decision variables from time domain to frequency domain, is proposed to reduce the dimensionality. The SOM couples a spectral dimensionality‐reduction method called Karhunen‐Loeve (KL) expansion within the routine of Nondominated Sorting Genetic Algorithm (NSGA‐II). The KL expansion is used to represent the decision variables as a series of terms that are deterministic orthogonal functions with undetermined coefficients. The KL expansion can be truncated into fewer significant terms, and consequently, fewer coefficients by a predetermined number. During optimization, operators of the NSGA‐II (e.g., crossover) are conducted only on the coefficients of the KL expansion rather than the large number of decision variables, significantly reducing the search space. The SOM is applied to the short‐term operation of a 10‐reservoir system in the Columbia River of the United States. Two scenarios are considered herein, the first with 140 decision variables and the second with 3360 decision variables. The hypervolume index is used to evaluate the optimization performance in terms of convergence and diversity. The evaluation of optimization performance is conducted for both conventional optimization model (i.e., NSGA‐II without KL) and the SOM with different number of KL terms. The results show that the number of decision variables can be greatly reduced in the SOM to achieve a similar or better performance compared to the conventional optimization model. For the scenario with 140 decision variables, the optimal performance of the SOM model is found with six KL terms. For the scenario with 3360 decision variables, the optimal performance of the SOM model is obtained with 11 KL terms.
Grammar and Emotion
Authors: Bazzanella Carla
Published: December 2015

Emotion and language, both of them constituting an integrated part of human behavior, social interaction, and culture, are inextricably intertwined in a variegated way, which is codified by grammar. Several parameters, such as individual and sociolinguistic variables, together with cultural background, affect the grammatical expressions of emotion, often paralleled by diverse means of expressing it, such as the expression of eyes and face, gaze, body posture, gestures, tears, smiles, and laughter.
Neoliberalism
Authors: Holborow Marnie
Published: December 2015

Neoliberalism is a contemporary social and political phenomenon of considerable historical significance. From its emergence in Anglo‐American conservative governments of the 1980s, elements of neoliberal thinking now dominate governments of all political hues, including those, like China, once formally opposed to the “free” market. Neoliberalism, in many respects the voice of global capitalism, has become the stamp of our age. Only relatively recently has neoliberalism become a point of reference within applied linguistics, mainly in relation to the marketization of language teaching and learning, the commodification of language skills, and the widespread use of corporate language in public discourse.
Item Response Theory
Authors: Ockey Gary J. , Choi Ikkyu
Published: December 2015

Item response theory (IRT) is an approach which can be used to estimate how much ability a person possesses on an unobservable construct, including those of interest to applied linguists. The theory assumes that a person can be placed on an ability continuum based on a score assigned to an observable performance.
“Central vessel sign” on 3T FLAIR* MRI for the differentiation of multiple sclerosis from migraine
Authors: Solomon Andrew J. , Schindler Matthew K. , Howard Diantha B. , Watts Richard , Sati Pascal , Nickerson Joshua P. , Reich Daniel S.
Published: December 2015

Objective

The diagnosis of multiple sclerosis (MS) presently relies on radiographic assessments of imperfect specificity. Recent data using T2* methodology for the detection of the “central vessel sign” (CVS) in MS lesions suggests this novel MRI technique may distinguish MS from other disorders. Our aim was to determine if evaluation for CVS on 3T FLAIR* MRI differentiates MS from migraine.

Methods

Patients with MS or migraine and a prior brain MRI demonstrating at least two hyperintense lesions ≥3 mm were recruited. Exclusion criteria included any additional comorbidity known to cause brain MRI abnormalities. 3T MRI was performed in each participant with administration of gadopentetate dimeglumine, and FLAIR* images were generated in postprocessing. The total number of discrete ovoid lesions ≥3 mm were counted on FLAIR, per participant, and subsequently evaluated for presence of CVS on FLAIR*. An exploratory method evaluating for CVS in a maximum of 12 lesions per subject was also completed.

Results

Ten participants with MS and 10 with migraine completed the study. The median percentage (quartiles) of lesions in MS participants with CVS was 84 (79, 94) compared to 22 (15, 54) in migraine (P = 0.008). In a subanalysis by brain region, in the subcortical and deep white matter, the median percentage (quartiles) of lesions in MS participants with CVS was 88 (81, 100) compared to 19 (11, 54) in migraine (P = 0.004). This difference was not identified in juxtacortical, periventricular, or infratentorial regions.

Interpretation

Identification of CVS using FLAIR* on 3T MRI helps differentiate MS from migraine, particularly in the subcortical and deep white matter.
Novel Fabrication of Bulk Fine‐Grained Al–Cu–Mg Alloy with Superior Mechanical Properties
Authors: Zheng Ruixiao , Ma Chaoli
Published: December 2015

Bulk fine‐grained 2024 Al alloy is prepared by spark plasma sintering and subsequent thermal–mechanical treatment. Bulk sample with mean grain size of 2.68 μm is firstly sintered using gas‐atomized 2024 Al alloy powder. After subsequent solid solution, cold rolling and aging processing, bulk fine‐grained 2024 Al alloy with simultaneously enhanced strength and ductility is obtained. Specifically, the tensile strength and total tensile elongation of the peak‐aged sample are 583 MPa and 16%, respectively. The enhanced strength is mainly attributed to the refined grain size and the high number density of nano‐precipitates. The enhanced ductility is attributed to the regained work‐hardening capability by aging.
Enhanced Cycling Stability of Rechargeable Li–O2 Batteries Using High‐Concentration Electrolytes
Authors: Liu Bin , Xu Wu , Yan Pengfei , Sun Xiuliang , Bowden Mark E. , Read Jeffrey , Qian Jiangfeng , Mei Donghai , Wang Chong‐Min , Zhang Ji‐Guang
Published: December 2015

The stability of electrolytes against highly reactive, reduced oxygen species is crucial for the development of rechargeable Li–O2 batteries. In this work, the effect of lithium salt concentration in 1,2‐dimethoxyethane (DME)‐based electrolytes on the cycling stability of Li–O2 batteries is investigated systematically. Cells with highly concentrated electrolyte demonstrate greatly enhanced cycling stability under both full discharge/charge (2.0–4.5 V vs Li/Li+) and the capacity‐limited (at 1000 mAh g−1) conditions. These cells also exhibit much less reaction residue on the charged air‐electrode surface and much less corrosion of the Li‐metal anode. Density functional theory calculations are used to calculate molecular orbital energies of the electrolyte components and Gibbs activation energy barriers for the superoxide radical anion in the DME solvent and Li+–(DME)
n solvates. In a highly concentrated electrolyte, all DME molecules are coordinated with salt cations, and the C–H bond scission of the DME molecule becomes more difficult. Therefore, the decomposition of the highly concentrated electrolyte can be mitigated, and both air cathodes and Li‐metal anodes exhibit much better reversibility, resulting in improved cyclability of Li–O2 batteries.
Electrohydrodynamic NanoDrip Printing of High Aspect Ratio Metal Grid Transparent Electrodes
Authors: Schneider Julian , Rohner Patrik , Thureja Deepankur , Schmid Martin , Galliker Patrick , Poulikakos Dimos
Published: December 2015

The transparent conducting electrode is an essential component in many contemporary and future devices, ranging from displays to solar cells. Fabricating transparent electrodes requires a balancing act between sufficient electrical conductivity and high light transmittance, both affected by the involved materials, fabrication methodology, and design. While metal films possess the highest conductivity at room temperature, a decent optical transmittance can only be achieved with ultrathin films. Structuring the metal into optically invisible nanowires has been shown to be promising to complement or even substitute transparent conductive oxides as dominant transparent electrode material. Here the out‐of‐plane fabrication capability of the recently developed method of electrohydrodynamic NanoDrip printing to pattern gold and silver nanogrids with line widths from 80 to 500 nm is demonstrated. This fully additive process enables the printing of high aspect ratio nanowalls and by that significantly improves the electrical performance, while maintaining the optical transmittance at a high level. Metal grid transparent electrodes optimized for low sheet resistances (8 Ω sq−1 at a relative transmittance of 94%) as well as optimized for high transmittance (97% at a sheet resistance of 20 Ω sq−1) are reported, which can be tailored on demand for the use in various applications.
Tunable White‐Light Emission from Conjugated Polymer‐Di‐Ureasil Materials
Authors: Willis‐Fox Niamh , Kraft Mario , Arlt Jochen , Scherf Ullrich , Evans Rachel C.
Published: December 2015

Conjugated polymer (CP)‐di‐ureasil composite materials displaying a tunable emission color from blue to yellow through white have been prepared using a simple sol–gel processing method. The tunability of the emission color arises from a combination of energy transfer between the di‐ureasil and the CP dopant and the excitation wavelength dependence of the di‐ureasil emission. Incorporation of the CP does not adversely affect the bulk or local structure of the di‐ureasil, enabling retention of the structural and mechanical properties of the host. Furthermore, CP‐di‐ureasils display superior thermal and photostability compared to the parent CPs. Thermogravimetric analysis shows that the onset of thermal decomposition can be increased by up to 130 °C for CP‐di‐ureasils, while photostability studies reveal a significant decrease in the extent of photodegradation. Steady‐state photoluminescence spectroscopy and picosecond time‐resolved emission studies indicate that the observed tunable emission arises as a consequence of incomplete energy transfer between the di‐ureasil and the CP dopant, resulting in emission from both species on direct excitation of the di‐ureasil matrix. The facile synthetic approach and tunable emission demonstrate that CP‐di‐ureasils are a highly promising route to white‐light‐emitters that simultaneously improve the stability and reduce the complexity of CP‐based multilayer device architectures.
Acoustic Detection of Phase Transitions at the Nanoscale
Authors: Vasudevan Rama K. , Khassaf Hamidreza , Cao Ye , Zhang Shujun , Tselev Alexander , Carmichael Ben , Okatan M. Baris , Jesse Stephen , Chen Long‐Qing , Alpay S. Pamir , Kalinin Sergei V. , Bassiri‐Gharb Nazanin
Published: December 2015

Materials near structural phase transitions find applications in a wide range of devices. Typically, phase transitions are determined macroscopically through measurements of relevant order parameters and related property coefficients. Here, a method for understanding electric field induced phase transitions in ferroelectrically active materials at the nanometer scale via acoustic detection with band‐excitation piezoresponse force microscopy (BE‐PFM) is introduced. Specifically, the field‐induced rhombohedral (R) to tetragonal (T) phase transition in single crystal 0.72PbMg1/3Nb2/3O3‐0.28PbTiO3 (PMN‐PT) is mapped. It is shown that due to sample heterogeneity, some regions are more prone to the R–T transition, and display signatures in the acquired piezoresponse loops, as well as pronounced softening in the elastic modulus (monitored via the resonant frequency and calibrated with models of cantilever dynamics) that occurs just prior to phase switching. Landau–Devonshire thermodynamic theory confirms the stability of the tetragonal phase under applied fields in PMN‐PT, while phase‐field modeling suggests that the transition evolves smoothly in the probed volume of the tip, both in agreement with the BE‐PFM results. These results confirm the validity and utility of utilizing acoustic changes at phase transitions to detect their onset in nanoscale probed volumes, allowing spatial mapping of their onset with unprecedented resolution.
High‐Efficiency Flexible Solar Cells Based on Organometal Halide Perovskites
Authors: Wang Yuming , Bai Sai , Cheng Lu , Wang Nana , Wang Jianpu , Gao Feng , Huang Wei
Published: December 2015

Flexible and light‐weight solar cells are important because they not only supply power to wearable and portable devices, but also reduce the transportation and installation cost of solar panels. High‐efficiency organometal halide perovskite solar cells can be fabricated by a low‐temperature solution process, and hence are promising for flexible‐solar‐cell applications. Here, the development of perovskite solar cells is briefly discussed, followed by the merits of organometal halide perovskites as promising candidates as high‐efficiency, flexible, and light‐weight photovoltaic materials. Afterward, recent developments of flexible solar cells based on perovskites are reviewed.
Preparation of PANI–PVA Composite Conductive Coatings Doped with Different Acid
Authors: Wang Xiao Hua , Tang Qi , Mu Yuan Hua , Li Chuan Qiang
Published: December 2015

The polyaniline–polyvinyl alcohol (PANI–PVA) composite conductive coatings were prepared by using PVA as the base material and doping with hydrochloride (HCl), dodecylbenzene sulfonic acid (DBSA), and aminosulfonic acid (NH2SO3H) aqueous solution. The influences of mass ratio between PANI and PVA, acid content, oxidant (ammonium persulfate, APS) content, reaction time, and drying temperature of film on the conductivity of coating film were studied. The result shows that in case the mass percentage of PVA is 40% and the drying temperature of film is 80℃, the conductivity of coating film has the highest conductivity. In case C(HC1) is 0.5 mol⋅L−1, the reaction time is 6 h, and n(APS/An) is 1.0, the maximum conductivity of HCl–PANI–PVA coating film is 1500 S⋅m−1; in case C(DBSA) is 1.0 mol⋅L−1, the reaction time is 8 h, and the n(APS/An) is 2.0, the maximum conductivity of DBSA–PANI–PVA coating film is 710 S⋅m−1; in case C(NH2SO3H) is 1.0 mol⋅L−1, the reaction time is 6 h, and the n(APS/An) is 2.0, the maximum conductivity of NH2SO3H–PANI–PVA coating film is 200 S⋅m−1. Among these PANI–PVA composite conductive coatings, the conductivity of HCl–PANI–PVA coating film is the highest. At the same time, the structure and conductive mechanism of composite materials were characterized and analyzed through infrared and ultraviolet spectrum and scanning electron microscopy.
Understanding the Light Soaking Effects in Inverted Organic Solar Cells Functionalized with Conjugated Macroelectrolyte Electron‐Collecting Interlayers
Authors: Xu Weidong , Xia Ruidong , Ye Tengling , Zhao Li , Kan Zhipeng , Mei Yang , Yan Congfei , Zhang Xin‐Wen , Lai Wen‐Yong , Keivanidis Panagiotis E. , Huang Wei
Published: December 2015

Three kinds of charged star‐shaped conjugated macroelectrolytes, named as PhNBr, TPANBr, and TrNBr, are synthesized as electron‐collecting interlayers for inverted polymer solar cells (i‐PSCs). Based on these well‐defined structured interlayer materials, the light soaking (LS) effect observed in i‐PSCs was studied systematically and accurately. The general character of the LS effect is further verified by studying additional i‐PSC devices functionalized with other common interlayers. The key‐role of UV photons was confirmed by electrochemical impedance spectroscopy and electron‐only devices. In addition, the ultraviolet photoelectron spectroscopy measurements indicate that the work function of the indium tin oxide (ITO)/interlayer cathode is significantly reduced after UV treatment. In these i‐PSC devices the LS effect originates from the adsorbed oxygen on the ITO substrates when oxygen plasma is used; however, even a small amount of oxygen from the ambient is also enough for triggering the LS effect, albeit with a weaker intensity. Our results suggest that the effect of adsorbed oxygen on ITO needs to be considered with attention while preparing i‐PSCs. This is an important finding that can aid the large‐scale manufacturing of organic solar cells via printing technologies, which do not always ensure the full protection of the device electrode substrates from oxygen.
Significant Roles of Intrinsic Point Defects in Mg2X (X = Si, Ge, Sn) Thermoelectric Materials
Authors: Liu Xiaohua , Xi Lili , Qiu Wujie , Yang Jiong , Zhu Tiejun , Zhao Xinbing , Zhang Wenqing
Published: December 2015

Point defects play a decisive role in the physical properties of thermoelectric materials and have been adopted as a new strategy to enhance thermoelectric properties. Here, the kinds of defects formed in Mg2X (X = Si, Ge, Sn) compounds are discussed and their influence mechanism on the thermoelectric performance by first‐principles calculation is understood. Mg vacancies and interstitial Mg are found to be the dominant defects and their competition directly determines the different intrinsic conduction of Mg2X. Mg2Si always shows n‐type, no matter what the Mg chemical potential is, while the conduction of Mg2Ge and Mg2Sn can change from p‐type to n‐type with increasing Mg chemical potential (Mg‐rich condition). Interestingly it is also found that interstitial Mg shares electrons with lattice Mg, changes the charge density distribution, and produces the impurity‐like level below the conduction band minimum. These results are helpful for understanding the roles of point defects in Mg2X and other thermoelectric compounds.
A Multisite‐Binding Switchable Fluorescent Probe for Monitoring Mitochondrial ATP Level Fluctuation in Live Cells
Authors: Wang Lu , Yuan Lin , Zeng Xian , Peng Juanjuan , Ni Yong , Er Jun Cheng , Xu Wang , Agrawalla Bikram Keshari , Su Dongdong , Kim Beomsue , Chang Young‐Tae
Published: December 2015

Adenosine triphosphate (ATP), commonly produced in mitochondria, is required by almost all the living organisms; thus fluorescent probes for monitoring mitochondrial ATP levels fluctuation are essential and highly desired. Herein, we report a multisite‐binding switchable fluorescent probe, ATP‐Red 1, which selectively and rapidly responds to intracellular concentrations of ATP. Live‐cell imaging indicated that ATP‐Red 1 mainly localized to mitochondria with good biocompatibility and membrane penetration. In particular, with the help of ATP‐Red 1, we successfully observed not only the decreased mitochondrial ATP levels in the presence of KCN and starvation state, but also the increased mitochondrial ATP levels in the early stage of cell apoptosis. These results indicate that ATP‐Red 1 is a useful tool for investigating ATP‐relevant biological processes.
A Catalytic DNA Activated by a Specific Strain of Bacterial Pathogen
Authors: Shen Zhifa , Wu Zaisheng , Chang Dingran , Zhang Wenqing , Tram Kha , Lee Christine , Kim Peter , Salena Bruno J. , Li Yingfu
Published: December 2015

Pathogenic strains of bacteria are known to cause various infectious diseases and there is a growing demand for molecular probes that can selectively recognize them. Here we report a special DNAzyme (catalytic DNA), RFD‐CD1, that shows exquisite specificity for a pathogenic strain of Clostridium difficile (C. difficile). RFD‐CD1 was derived by an in vitro selection approach where a random‐sequence DNA library was allowed to react with an unpurified molecular mixture derived from this strain of C. difficle, coupled with a subtractive selection strategy to eliminate cross‐reactivities to unintended C. difficile strains and other bacteria species. RFD‐CD1 is activated by a truncated version of TcdC, a transcription factor, that is unique to the targeted strain of C. difficle. Our study demonstrates for the first time that in vitro selection offers an effective approach for deriving functional nucleic acid probes that are capable of achieving strain‐specific recognition of bacterial pathogens.
Asymmetric Synthesis of Spiropyrazolones by Sequential Organo‐ and Silver Catalysis
Authors: Hack Daniel , Dürr Alexander B. , Deckers Kristina , Chauhan Pankaj , Seling Nico , Rübenach Lukas , Mertens Lucas , Raabe Gerhard , Schoenebeck Franziska , Enders Dieter
Published: December 2015

A stereoselective one‐pot synthesis of spiropyrazolones through an organocatalytic asymmetric Michael addition and a formal Conia‐ene reaction has been developed. Depending on the nitroalkene, the 5‐exo‐dig‐cyclization could be achieved by silver‐catalyzed alkyne activation or by oxidation of the intermediate enolate. The mechanistic pathways have been investigated using computational chemistry and mechanistic experiments.
An Improved System for the Aqueous Lipshutz–Negishi Cross‐Coupling of Alkyl Halides with Aryl Electrophiles
Authors: Bhonde Vasudev R. , O'Neill Brian T. , Buchwald Stephen L.
Published: December 2015

The development of a palladacyclic precatalyst supported by a new biaryl(dialkyl)phosphine ligand (VPhos) in combination with octanoic acid/sodium octanoate as a simple and effective surfactant system provided an improved catalyst system for the rapid construction of a broad spectrum of alkylated scaffolds from alkyl zinc reagents generated in situ.
Molecular Polyarsenides of the Rare‐Earth Elements
Authors: Arleth Nicholas , Gamer Michael T. , Köppe Ralf , Konchenko Sergey N. , Fleischmann Martin , Scheer Manfred , Roesky Peter W.
Published: December 2015

Reduction of [Cp*Fe(η5‐As5)] with [Cp′′2Sm(thf)] (Cp′′=η5‐1,3‐(tBu)2C5H3) under various conditions led to [(Cp′′2Sm)(μ,η4:η4‐As4)(Cp*Fe)] and [(Cp′′2Sm)2As7(Cp*Fe)]. Both compounds are the first polyarsenides of the rare‐earth metals. [(Cp′′2Sm)(μ,η4:η4‐As4)(Cp*Fe)] is also the first d/f‐triple decker sandwich complex with a purely inorganic planar middle deck. The central As42− unit is isolobal with the 6π‐aromatic cyclobutadiene dianion (CH)42−. [(Cp′′2Sm)2As7(Cp*Fe)] contains an As73− cage, which has a norbornadiene‐like structure with two short As−As bonds in the scaffold. DFT calculations confirm all the structural observations. The As−As bond order inside the cyclo As4 ligand in [(Cp′′2Sm)(μ,η4:η4‐As4)(Cp*Fe)] was estimated to be in between an As−As single bond and a formally aromatic As42− system.
Enhanced production of optically pure d (–) lactic acid from nutritionally rich Borassus flabellifer sugar and whey protein hydrolysate based–fermentation medium
Authors: Reddy Tadi Subbi Rami , E. V. R. Arun , Limaye Anil Mukund , Sivaprakasam Senthilkumar
Published: December 2015

The aim of this study is to optimize the production of optically pure d (–) lactic acid (DLA) employing a cost‐effective production medium. Based on the designed biomass approach, Sporolactobacillus inulinus NBRC 13595 was found to exhibit high DLA titer (19.0 g L−1) and optical purity (99.6%). A cost‐effective medium was constituted using Palmyra palm jaggery (PJ) from Borassus flabellifer and whey protein hydrolysate (WPH) as carbon and nitrogen sources, respectively. Plackett–Burman design indicated that PJ, WPH, and MnSO4 as significant variables influence DLA production. A rotatable central composite design and response surface methodology were used to optimize the PJ and WPH concentrations. A maximum DLA titer (170.14 g L−1) was predicted for 222.24 g L−1 of PJ and 11.99 g L−1 of WPH, respectively. Fermentation experimental results exhibited a maximum DLA titer (189.0 ± 8.53 g L−1) and productivity (5.25 ± 0.24 g L−1 H−1), which is the highest ever reported for DLA production from a renewable feedstock in the batch process. The present investigation substantiates that the potential application of economically viable raw feedstocks (PJ and WPH) for enhanced DLA production, which is attributed to 2.5‐fold reduction in DLA production cost compared with conventional medium.
Energieübertragung für ein System gekoppelter Oszillatoren II Theorie des Restmoleküls
Authors: Kohlmaier G. H. , Hensel V. , Siré E. O.
Published: December 2015

In einer früheren Arbeit wurde von den Autoren Nikitin und Kohlmaier ein phänomenologisch eingeführter “Reibungskoeffizient” γ benutzt, um die während eines Stoßvorganges stattfindende Energieabwanderung aus der Endbindung in den Molekülrest zu beschreiben. In dieser Arbeit wird der Koeffizient γ über eine mechanische Theorie atomistisch begründet.
The Thermal Conductivity of Mixtures of Hydrogen with the Monatomic Gases
Authors: Assael M. J. , Wakeham W. A.
Published: December 2015

The paper presents experimental results for the thermal conductivity of hydrogen with the three monatomic gases: neon, argon, and krypton. The measurements have been carried out in a transient hot‐wire apparatus at 35°C within the pressure range 2–9 MPa. The accuracy of the thermal conductivity data is estimated as one of ± 0.2%. — Intermodular pair potentials for the interaction of hydrogen with the monatomic gases, obtained from molecular beam and spectroscopic studies, provide only a moderately good representation of the experimental data in the limit of zero density. The discrepancies are attributed in part to the limitations of the available kinetic theory formulae for the thermal conductivity of polyatomic gas mixtures. The density dependence of the thermal conductivity of the mixtures is well described by a calculation scheme based on the modified Enskog theory.
Einfluß von Molmasse und Molekülverzweigungen auf das Entmischungsverhalten von Ethylen/Polyethylen‐Systemen unter Hochdruck
Authors: Spahl Roland , Luft Gerhard
Published: December 2015

The phase behaviour of mixtures of ethylene and polyethylene was studied under pressures up to 200 MPa at temperatures between 383 and 473 K simultaneously by optical and analytical measurements. Three different low density polyethylenes with number average molecular weights of 1100, 19500 and 55000 g/mol were used. In order to show the influence of long chain branching the results were compared with datas published on mixtures of ethylene and linear polyethylenes. It was found that the heterogeneous region extends with rising molecular weight of the polymer and falling temperatures. With branched polyethylenes the critical pressure was lower. The dependency of the critical pressure on the molecular weight and the branching could be expressed by an equation analogous to the relation between the critical temperature and the polymer molecular weight in diluted solutions.
1‐ und 2‐Elektronenschritte bei der Oxidation substituierter Paraphenylendiamine mit verschiedenen Oxidationsmitteln. II. Reaktionen mit Hexacyanoferrat
Authors: Nickel Ulrich , Jaenicke Walther
Published: December 2015

The oxidation kinetics of several N‐ and ring‐alkylated p‐phenylenediamines with hexacyanoferrate(III) (F3) was studied in the pH‐range 2,5 – 9 by means of a multimixing stopped flow technique which is described in detail. The p‐phenylene diamine‐derivatives (R) are oxidized via reversible one‐electron steps to the semiquinone diimine radical S (rate constants k1, k−1) and the quinone diimine T (rate constants k2, k−2). – k1 and k−1 could be measured directly for all compounds, k2 and k−2 for two derivatives. – Only the unprotonated species of R, S, T, F3 are reactive. The reduction is possible by the unprotonated Fe(CN)4‐6 (F2) and by its protonated form F2H. The complexes of F2 with alkali ions are inactive. In this way the respective association constants could be calculated. The kinetics of the reaction was compared with the thermodynamics, represented by potential‐pH‐diagrams. – The activation parameters of the reaction of p‐phenylene diamine‐derivatives with F3, F2 and also with iodine were measured. The activation energies of the second step (k2, k−2) are negligible. – Both oxidants attack the alkylated aminogroup of the p‐phenylene diamine derivatives. The radical cation is deprotonated before it is oxidized.
NMR Studies on the Motion of Dimethylammonium Ions in [(CH3)2NH2]2SnCl6 and [(CH3)2NH2]2TeCl6 as well as Their Partially Deuterated Analogs
Authors: Ishida Hiroyuki , Ikeda Ryuichi , Nakamura Daiyu
Published: December 2015

The temperature dependences of proton spin‐lattice relaxation time, T1 and of the second moment of 1H NMR absorptions were studied in dimethylammonium hexachlorostannate(IV), hexachlorotellurate(IV), and their partially deuterated analogs. From X‐ray powder patterns taken at room temperature, the tellurium(IV) complex was found to be isomorphous with the tin(IV) complex. For the tellurium complex, a phase transition was located at 169 K by DTA experiments. By 1H NMR, two kinds of motions, the reorientation of the methyl groups about their respective C ‐ N bond axis and the 180° flip motion of the whole cation about its two fold pseudosymmetry axis, were observed for the cation in the crystals. The activation energies were evaluated for these motional modes. Besides these two motions, large‐amplitude librations or small angle reorientations of the cation about its pseudosymmetry axis are deduced to take place at high temperatures.
Downsizing and Supersizing: How Changes in Product Attributes Influence Consumer Preferences
Authors: Jami Ata , Mishra Himanshu
Published: December 2015

This paper investigates how changing the value of one attribute while keeping other attributes constant influences consumers' judgments and behaviors. We find that in two options, a proportionally equal change in one attribute tilts people's preference toward the option with higher (or lower) absolute magnitude of change when the change is desirable (or undesirable). We propose that when individuals face an attribute change, they use a deliberative and effortful response, known as System 2, to detect the change. However, they rely less on this system to evaluate the changed options. Instead, a more automatic System 1 processing influences their decision by making them apply the bigger‐is‐better heuristic (bigger‐is‐worse for an undesirable change) to prefer the option with the highest (lowest) absolute magnitude of change. Six studies demonstrate this phenomenon in both lab and real settings and support our hypothesis. Copyright © 2013 John Wiley & Sons, Ltd.