bluuebunny/crossref_metadata_2025 huggingface dataset:
First use of p-tert-butylcalix[4]arene-tetra-O-acetate as a nanoreactor having tunable selectivity towards cross azo-compounds by trapping silver ions
Authors: Sarkar Piyali , Mukhopadhyay Chhanda
Published: August 2015

p-tert-Butylcalix[4]arene-tetra-O-acetate was established for the first time as a member of the nanoreactor series, even without having any –OH group.
New physiologically-relevant liver tissue model based on hierarchically cocultured primary rat hepatocytes with liver endothelial cells
Authors: Xiao Wenjin , Perry Guillaume , Komori Kikuo , Sakai Yasuyuki
Published: August 2015

We established a physiologically-relevant liver tissue model hierarchically consisting of two complete layers of primary rat hepatocytes and human liver sinusoidal endothelial cells (TMNK-1) on an oxygen-permeable polydimethylsiloxane (PDMS) membrane.
Spatiotemporal norepinephrine mapping using a high-density CMOS microelectrode array
Authors: Wydallis John B. , Feeny Rachel M. , Wilson William , Kern Tucker , Chen Tom , Tobet Stuart , Reynolds Melissa M. , Henry Charles S.
Published: August 2015

Electrochemical imaging with high spatiotemporal resolution of dynamic norepinephrine distributions is achieved using microfluidics and a high-density CMOS platinum microelectrode array with an on-board potentiostat.
Research highlights: microfluidically-fabricated materials
Authors: Koh Jaekyung , Wu Chueh-Yu , Kittur Harsha , Di Carlo Dino
Published: August 2015

Injectable microporous gels formed from microfluidically-generated building blocks – Optofluidic fabrication of complex 3D particles using inertial flow sculpting – Scaling microparticle production with contact flow lithography.
Polymerized phosphonium-based ionic liquids as stationary phases in gas chromatography: performance improvements by addition of graphene oxide
Authors: González-Álvarez Jaime , Arias-Abrodo Pilar , Puerto Marcos , Viguri Maialen Espinal , Perez Julio , Gutiérrez-Álvarez María Dolores
Published: August 2015

The incorporation of graphene oxide sheets into phosphonium ionic liquid stationary phases led to a great improvement of their separation efficiencies.
B28: the smallest all-boron cage from an ab initio global search
Authors: Zhao Jijun , Huang Xiaoming , Shi Ruili , Liu Hongsheng , Su Yan , King R. Bruce
Published: August 2015

Ourab initioglobal searches reveal the lowest-energy cage for B28, which is built from two B12units and prevails over the competing structural isomers such as planar, bowl, and tube.
Utilizing the protein corona around silica nanoparticles for dual drug loading and release
Authors: Shahabi Shakiba , Treccani Laura , Dringen Ralf , Rezwan Kurosch
Published: August 2015

The protein corona, which forms spontaneously around silica nanoparticles in serum-containing media, can be exploited for delivery of multiple drugs.
The effect of with/without resonance-mediated interactions on the organic solar cell performance of new 2D π-conjugated polymers
Authors: Chakravarthi Nallan , Gunasekar Kumarasamy , Kranthiraja Kakaraparthi , Kim Taeik , Cho Woosum , Kim Chang Su , Kim Dong-Ho , Song Myungkwan , Jin Sung-Ho
Published: August 2015

Bis-tolane as an integrated part of the benzodithiophene donor unit for OSCs.
Synthesis and properties of polyesters derived from renewable eugenol and α,ω-diols via a continuous overheating method
Authors: Hu Keling , Zhao Dongping , Wu Guolin , Ma Jianbiao
Published: August 2015

Two series of thermoplastic polyesters derived from renewable eugenol and linear aliphatic α,ω-diols were prepared. The dependence of the properties on the α,ω-diol length was investigated.
Pore structure and sorption characterization of titanosilicates obtained from concentrated precursors by the sol–gel method
Authors: Oleksiienko O. , Meleshevych S. , Strelko V. , Wolkersdorfer Ch. , Tsyba M. M. , Kylivnyk Yu. M. , Levchuk I. , Sitarz M. , Sillanpää M.
Published: August 2015

Our novel titanosilicate sol–gel synthesis yielded effective sorption materials for Sr2+ and Cs+ decontamination from polluted ground and waste water.
Synthesis, characterization, and adsorption properties of ionic liquid-modified hypercrosslinked polystyrene resins
Authors: Wu Xiaoyu , Liu Yi , Liu Yongfeng , Di Duolong , Guo Mei , Zhao Lei
Published: August 2015

Ionic liquid modified hypercrosslinked polymeric resins were synthesized and their adsorptive characteristics for catechin were studied.
Treatment of textile wastewater under visible LED lamps using CuO/ZnO nanoparticles immobilized on scoria rocks
Authors: Mahdizadeh F. , Aber S.
Published: August 2015

ZnO and CuO thin films were synthesized by a sol–gel and direct crystallization method on granular porous natural scoria respectively and CuO/ZnO/scoria was used for water treatment under visible light irradiation.
Preparative separation of alkaloids from Litsea cubeba using combined applications of pH-zone-refining and high-speed counter-current chromatography
Authors: Sun Changlei , Li Jia , Wang Daijie , Yu Jinqian , Wang Xiao , Huang Luqi
Published: August 2015

pH-zone-refining counter-current chromatography and high-speed counter-current chromatography are used for separation of alkaloids from the extract of Litsea cubeba.
Laser desorption ionization (LDI) silicon nanopost array chips fabricated using deep UV projection lithography and deep reactive ion etching
Authors: Morris Nicholas J. , Anderson Heather , Thibeault Brian , Vertes Akos , Powell Matthew J. , Razunguzwa Trust T.
Published: August 2015

A nanofabricated laser desorption ionization mass spectrometry (LDI-MS) chip for quantitation of small molecules.
Silver and gold nanoparticles from Sargentodoxa cuneata: synthesis, characterization and antileishmanial activity
Authors: Ahmad Aftab , Syed Fatima , Shah Akram , Khan Zahid , Tahir Kamran , Khan Arif Ullah , Yuan Qipeng
Published: August 2015

Promising antileishmanial properties were observed with Sargentodoxa cuneata mediated Ag and AuNPs. This study opens a platform for the synthesis of new leishmanicidal agents.
A miniature room temperature formaldehyde sensor with high sensitivity and selectivity using CdSO4 modified ZnO nanoparticles
Authors: Chang Xinghua , Peng Mi , Yang Junfeng , Wang Teng , liu Yu , Zheng Jie , Li Xingguo
Published: August 2015

A light activated miniature formaldehyde sensor working at room temperature is fabricated by CdSO4 modified ZnO nanoparticles.
In vitro nucleus nanoprobe with ultra-small polyethylenimine functionalized graphene quantum dots
Authors: Wang Han , Wang Xiaomin
Published: August 2015

Ultra-small polyethylenimine functionalized graphene quantum dots with unique nucleus labeling property are reported.
Suppressing phase coarsening in immiscible polymer blends using nano-silica particles located at the interface
Authors: Feng Jian-Ming , Liu Xi-Qiang , Bao Rui-Ying , Yang Wei , Xie Bang-Hu , Yang Ming-Bo
Published: August 2015

Coalescence suppressing effect of nanoparticles at the interface of polymer blends.
Synthesis and electrochemical properties of Li(Fe0.5Co0.5)BO3
Authors: Le Roux Barbara , Bourbon Carole , Colin Jean-François , Pralong Valérie
Published: August 2015

A new borate compound LiFe0.5Co0.5BO3 has been successfully synthesized for the first time by a multiple-step process. This compound delivers a very interesting first discharge capacity of 120 mA h g−1 at C/20 rate without in situ carbon coating.
Structurally simple phenanthroimidazole-based bipolar hosts for high-performance green and red electroluminescent devices
Authors: Wang Kai , Wang Shipan , Wei Jinbei , Miao Yang , Zhang Zhenyu , Zhang Zuolun , Liu Yu , Wang Yue
Published: August 2015

Two structurally simple and easily synthesized phenanthroimidazole-based bipolar-transporting host materials realized efficient green and red phosphorescent OLEDs with low efficiency roll-off.
Hypoiodous acid-catalyzed regioselective geminal addition of methanol to vinylarenes: synthesis of anti-Markovnikov methyl acetals
Authors: Peraka Swamy , Mameda Naresh , Marri Mahender Reddy , Kodumuri Srujana , Chevella Durgaiah , Sripadi Prabhakar , Nama Narender
Published: August 2015

A new metal-free catalytic approach for the synthesis of anti-Markovnikov methyl acetals from vinylarenes based on in situ generated HOI species is reported. The mechanistic investigations provided the solid evidence for the proposed mechanism.
On-chip ultrasonic sample preparation for cell based assays
Authors: Iranmanesh Ida , Ramachandraiah Harisha , Russom Aman , Wiklund Martin
Published: August 2015

We demonstrate pre-alignment, size-based separation, isolation, trapping, up-concentration and fluorescence monitoring of cells in a sequence by the use of a multi-step, three-transducer acoustophoresis chip designed for cellular sample preparation.
Excitonic splittings in molecular dimers: why static ab initio calculations cannot match them
Authors: Ottiger Philipp , Köppel Horst , Leutwyler Samuel
Published: August 2015

We show experimentally that excitonic splittings in symmetric dimers calculatedab initioare 5–25 times too large, and explain why using vibronic coupling theory.
Nano-rheology of hydrogels using direct drive force modulation atomic force microscopy
Authors: Nalam Prathima C. , Gosvami Nitya N. , Caporizzo Matthew A. , Composto Russell J. , Carpick Robert W.
Published: August 2015

A quantitative and novel nanoscale viscoelastic spectroscopy tool for soft matter was developed. The study highlights the transition in the probe–material contact mechanical behavior of hydrogels especially when the applied strain rates and the material relaxation become comparable.
A high performance polysiloxane-based single ion conducting polymeric electrolyte membrane for application in lithium ion batteries
Authors: Rohan Rupesh , Pareek Kapil , Chen Zhongxin , Cai Weiwei , Zhang Yunfeng , Xu Guodong , Gao Zhiqiang , Cheng Hansong
Published: August 2015

A polysiloxane based SIPE with grafted bis(sulfonyl)imide groups performs successfully in a temperature range of 25–80 °C with high charge–discharge rates.
Thiophene-modified perylenediimide as hole transporting material in hybrid lead bromide perovskite solar cells
Authors: Das Jaykrushna , Bhaskar Kanth Siram Raja , Cahen David , Rybtchinski Boris , Hodes Gary
Published: August 2015

A small molecule based on N,N′-dialkyl perylenediimide (PDI) as core derivatized with thiophene moieties (Th-PDI) was synthesized.
Valence band engineering and thermoelectric performance optimization in SnTe by Mn-alloying via a zone-melting method
Authors: He Jun , Tan Xiaojian , Xu Jingtao , Liu Guo-Qiang , Shao Hezhu , Fu Yajie , Wang Xue , Liu Zhu , Xu Jiaqiang , Jiang Haochuan , Jiang Jun
Published: August 2015

Mn alloying in SnTe increases the band gap and decreases the energy separation between the light and heavy hole valence bands, leading to a significant enhancement in the Seebeck coefficient. The maximum ZT of ~1.25 is found at 920 K for p-type SnMn0.07Te.
Generalized synthesis and evaluation of formation mechanism of metal oxide/sulphide@C hollow spheres
Authors: Saha Arka , Bharmoria Pankaj , Mondal Aniruddha , Ghosh Subhash C. , Mahanty Sourindra , Panda Asit Baran
Published: August 2015

A generalized novel sucrose–CTAB-based soft template approach for synthesizing metal oxide/sulphide hollow spheres and the corresponding formation mechanism are reported.
TiO2-B nanorod based competitive-like non-enzymatic photoelectrochemical sensing platform for noninvasive glucose detection
Authors: Zhang Shupei , Xu Guifang , Gong Lingshan , Dai Hong , Li Yilin , Hong Zhensheng , Lin Yanyu
Published: August 2015

A new competitive-like non-enzymatic photoelectrochemical biosensor was established for the first time based on a TiO2-B nanorod platform for noninvasive glucose detection.
Improving antifouling ability and hemocompatibility of poly(vinylidene fluoride) membranes by polydopamine-mediated ATRP
Authors: Jiang Jinhong , Zhang Peibin , Zhu Liping , Zhu Baoku , Xu Youyi
Published: August 2015

A versatile strategy for the preparation of polymer membranes with remarkably improved antifouling properties and hemocompatibility is developed through a simple blending process and secondary treatments.
A chemical link between Ge–Sb–Te and In–Sb–Te phase-change materials
Authors: Deringer Volker L. , Zhang Wei , Rausch Pascal , Mazzarello Riccardo , Dronskowski Richard , Wuttig Matthias
Published: August 2015

Chemical-bonding theory reveals a common electronic “fingerprint” in seemingly different phase-change materials for data storage.
On‐chip picosecond resolution timing measurement using time amplifier
Authors: Zhang Peiyong , Feng Chenhui , Wang Huiyan
Published: August 2015

Timing parameters of the standard cell library are essential for static timing analysis. An on‐chip picosecond resolution timing measurement system is presented. The system measures the rise/fall time of the signal and the setup/hold time of the flip flop. Compared with the SPICE simulation, the on‐chip physical measurement considerably improves the resolution of the timing parameters.
Delay constrained throughput optimised joint scheduling and link adaptation scheme based on imperfect channel state information
Authors: Taki Mehrdad
Published: August 2015

This study presents novel joint scheduling and link adaptation schemes (JSL) to maximise a weighted sum of throughputs of wireless links, while their possibly different minimum required throughputs and packet error rate (PER), average power and delay constraints are provisioned. Weights are assigned based on the importance and requirements of the links. Notable features of the proposed scheme in comparison with the previously presented utility based scheduling schemes are: (a) in the designed scheme a statistical bound is presented for the delay instead of average delay constraint or long term queuing delay behaviour, (b) designed transmission scheme utilises adaptive modulation and coding provisioning PER constraint and may be integrated with H automatic repeat request in data link layer to provide error free communication, (c) the presented schemes are designed based on imperfect signal‐to‐noise ratio (SNR) estimate of the links. In addition to an analytical approach, a JSL scheme based on sub‐gradient projection (JSL‐SP) is presented in which there is no need to have SNRs probability density functions. Numerical results demonstrate how the proposed JSL schemes outperforms the benchmark schemes and effectively meets various user's requirements.
Detection of stator incipient faults and identification of faulty phase in three‐phase induction motor – simulation and experimental verification
Authors: Rama Devi Neerukonda , Siva Sarma Dhanikonda V.S.S. , Ramana Rao Pulipaka V.
Published: August 2015

Motor current signature analysis is a well‐known method for the diagnosis of stator incipient faults on a three‐phase induction motor (IM). In classical motor current signature analysis the fault feature is extracted by analysing the frequency spectrum obtained from the Fourier analysis. However, for proper fault diagnosis, time–frequency domain analysis is required. This study proposes an algorithm based on wavelet analysis for detection of stator incipient faults and identification of faulty phase in three‐phase IM. A turn level distributed parameter model of a 3‐hp IM is considered for the simulation of inter‐turn faults. The parameters used in the simulated model are calculated by conducting experiments on a 3‐hp IM. This model is validated by comparing the frequency response of the simulated model with the frequency response measured on practical machine. The proposed algorithm uses an adaptive threshold‐based logic for detecting the inter‐turn faults and identifying the faulty phase. The algorithm is validated with data generated by the specially designed 3‐hp IM. The experimental and simulation results show that the proposed algorithm is effective in detecting the inter‐turn faults and identifying the faulty phase even in the presence of supply unbalance conditions.
High‐voltage‐gain quadratic boost converter with voltage multiplier
Authors: Zhang Neng , Sutanto Danny , Muttaqi Kashem M. , Zhang Bo , Qiu Dongyuan
Published: August 2015

In this study, a novel high‐gain quadratic boost converter with a voltage multiplier circuit is presented to give an alternative power electronic circuit for high‐voltage conversion and low‐to‐medium power applications. The proposed converter combines the traditional quadratic boost converter and a coupled‐inductor‐based voltage multiplier circuit. Compared with the traditional quadratic boost converter, the proposed converter can obtain a much higher output voltage under the same duty cycle and input voltage, and can also reduce the voltage stresses in the power devices. Moreover, the serious input current ripple in the converter with coupled‐inductor is reduced. Consequently, the efficiency and the reliability can be improved by using semiconductors with low‐voltage level and high performance. The theoretical analysis of the proposed converter is verified by the experimental results.
High‐step‐up single‐switch DC–DC converter with low voltage spike
Authors: Hwu Kuo‐Ing , Jiang Wen‐Zhuang , Yang Li‐Ching
Published: August 2015

DC–DC converters using coupled inductors have been developed for many years. However, to prevent the high voltage spikes across main switches and diodes, the leakage inductance energy recycling will be an important issue. Consequently, a high‐step‐up single‐switch DC–DC converter with low voltage stress is presented herein. The proposed converter integrates a coupled inductor and switched capacitors not only to realise a high voltage gain but also to recycle the leakage inductance energy. Accordingly, the voltage spikes on the switch and diodes can be clamped at some values as low as possible. Moreover, similar to the traditional boost converter, the source terminal of the MOSFET is connected to the ground. Therefore, no isolated driver is required. Eventually, the detailed analysis of the proposed converter and an experimental prototype with 12 V input voltage, 200 V output voltage and 100 W output power are provided to verify the effectiveness of the proposed converter.
Current source inverter‐based photovoltaic system with enhanced active filtering functionalities
Authors: Geury Thomas , Pinto Sonia , Gyselinck Johan
Published: August 2015

This study proposes a three‐phase photovoltaic (PV) inverter, with active power filtering capability that allows for maximum power point tracking (MPPT) and a nearly unitary power factor (PF) in the connection to the low voltage grid. A single‐stage current source inverter, with an inductive DC link, connects the PV array to the three‐phase grid for reduced cost and improved performances, and the MPPT algorithm controls directly the power of the PV array. On the basis of the power balance of the whole system, the grid current references are generated in a grid‐synchronised dq frame allowing for the mitigation of low‐frequency current harmonics introduced by a non‐linear load connected at the point of common coupling, without the need for additional measurements. Active damping is used to minimise filter losses and reduce the high‐frequency harmonics that result from the semiconductors switching. Simulation and experimental results are presented in unloaded and loaded situations, and with varying irradiance, to confirm the active filtering, PF regulation and MPPT operate correctly.
Electromagnetic interference noise suppression of writing/reading flash memory with multiple‐execution control program
Authors: Lin Han‐Nien , Kuo Chung‐Wei , Chen Hung‐Chi
Published: August 2015

Currently flash memory is widely used for data storage of mobile communication and automobile electronics. In this study the control program of multiple‐execution has been designed to suppress the components and level of electromagnetic interference (EMI) noise generated during the data writing/reading of flash memory. The method designed by us can reduce the EMI noise levels of writing and reading operations by 4.39 dB and 2.91 dB respectively, while reducing the EMI noise components by 58.3% and 54.5% respectively, such that the noise interference by flash memory can be effectively reduced when it is used for various electronic devices. Especially for the automobile electronic systems, where the reduction of EMI noise interference can assure driving safety, and the reception sensitivity can be enhanced by suppressing the interference of RF module resulted from platform noise.
A compact, coaxial shunt current diagnostic for X pinches
Authors: Wang Liangping , Zhang Jinhai , Li Mo , Zhang Xinjun , Zhao Chen , Zhang Shaoguo
Published: August 2015

A compact coaxial shunt was applied in X-pinches experiments on Qiangguang pulsed power generator. The coaxial shunt was designed to have a compact construction for smaller inductance and more, for conveniently assembling upon the X pinch load structure. The coaxial shunt is also a cheap current probe and was easily built by research groups. The shunt can monitor a 100 kA high current with a 100 ns rise time. The calibration results showed that the probe used in the experiments has a resistance of 3.2 mΩ with an uncertainty of 3%, and its response time to the step signal is less than 7 ns.
Site specific atomic polarizabilities in endohedral fullerenes and carbon onions
Authors: Zope Rajendra R. , Bhusal Shusil , Basurto Luis , Baruah Tunna , Jackson Koblar
Published: August 2015

We investigate the polarizability of trimetallic nitride endohedral fullerenes by partitioning the total polarizability into site specific components. This analysis indicates that the polarizability of the endohedral fullerene is essentially due to the outer fullerene cage and has insignificant contribution from the encapsulated unit. Thus, the outer fullerene cages effectively shield the encapsulated clusters and behave like Faraday cages. The polarizability of endohedral fullerenes is slightly smaller than the polarizability of the corresponding bare carbon fullerenes. The application of the site specific polarizabilities to C60@C240 and C60@C180 onions shows that, compared to the polarizability of isolated C60 fullerene, the encapsulation of the C60 in C240 and C180 fullerenes reduces its polarizability by 75% and 83%, respectively. The differences in the polarizability of C60 in the two onions is a result of differences in the bonding (intershell electron transfer), fullerene shell relaxations, and intershell separations. The site specific analysis further shows that the outer atoms in a fullerene shell contribute most to the fullerene polarizability.
Seebeck effect in a battery-type thermocell
Authors: Kobayashi Wataru , Kinoshita Akemi , Moritomo Yutaka
Published: August 2015

We demonstrated that battery-type thermocells, which consist of two paste-type electrodes with the same active material and electrolyte, show the Seebeck effect. The magnitudes of electrochemical Seebeck coefficient (S) of the thermocells with several layered oxides were evaluated: −12.7 μV/K for Na0.99CoO2, −29.7 μV/K for Na0.52MnO2, −22.4 μV/K for Na0.51Mn0.5Fe0.5O2, and −6.8 μV/K for LiCoO2. In the thermocell with Na0.99CoO2, time-dependence of the electromotive force (ΔV) at a constant temperature difference (ΔT) was well reproduced by a mean-field approach of the chemical potential (ϕ)—Na+ concentration (x) relationship, indicating that the Na+ intercalation/deintercalation plays an intrinsic role in the electrochemical Seebeck effect.
Modeling of a metallic truncated cone for electromagnetic capacitive sensors
Authors: Bartolucci Giancarlo , Sardi Giovanni Maria , Marcelli Romolo , Proietti Emanuela , Lucibello Andrea , Stoja Endri , Frezza Fabrizio
Published: August 2015

This paper presents an electromagnetic modeling of a grounded metallic truncated cone to be used for calibration purposes of a microwave imaging system. The basic idea is to demonstrate the equivalence between the cone and a cylinder having a suitable radius, in order to simplify the computation of its capacity with respect to ground. A mathematical expression for the capacitance of the uniform cylinder is presented, and its validity is confirmed by comparing the data provided by this formula with numerical values given by a commercial simulator. Starting from this analytic result, the model of the cone is presented, and a procedure for the choice of the cylinder radius is discussed in detail. This methodology can be applied to calculate the contribution to the stray capacitance of a metallic tip used for scanning probe microscopy, and specifically for microwave sensing applications. In particular, the capacitance due to the conic part of the probe can be quantified, an operation that is usually a difficult task when trying to separate it from contribution of the experimental setup. In our opinion, this issue is very important to improve the accuracy of system calibration in the scanning microwave microscopy technique.
Mode-coupling approach for the slow dynamics of a liquid on a spherical substrate
Authors: Vest Julien-Piera , Tarjus Gilles , Viot Pascal
Published: August 2015

We study the dynamics of a one-component liquid constrained on a spherical substrate, a 2-sphere, and investigate how the mode-coupling theory (MCT) can describe the new features brought by the presence of curvature. To this end we have derived the MCT equations in a spherical geometry. We find that, as seen from the MCT, the slow dynamics of liquids in curved space at low temperature does not qualitatively differ from that of glass-forming liquids in Euclidean space. The MCT predicts the right trend for the evolution of the relaxation slowdown with curvature but is dramatically off at a quantitative level.
Exact solutions to the interfacial surfactant transport equation on a droplet in a Stokes flow regime
Authors: Kallendorf Christina , Fath Anja , Oberlack Martin , Wang Yongqi
Published: August 2015

In the research literature there exist very rare analytical solutions of the surfactant transport equation on an interface. In the present article, we derive sets of exact solutions to interfacial convection-diffusion equations which describe the interfacial transport of insoluble surfactants in a two-phase flow. The investigated model is based on a Stokes flow setting where a spherical shaped inner phase is dispersed in an outer phase. Under the assumption of the small capillary number, the deformation of the spherical phase interface is not taken into account. Neglecting the dependence of the surface tension on the interfacial surfactant concentration, hence neglecting the Marangoni effect, general exact solutions to the surfactant conservation law on the spherical surface with both convective and diffusive terms are provided by means of Heun’s confluent function. For the steady case, it is shown that these solutions collapse to a simple exponential form. Furthermore, for the purely diffusive problem, exact solutions are constructed using Legendre polynomials. Such analytical solutions are very valuable as benchmark problems in numerical investigations.
Rotation of methane molecules in dimers and small clusters
Authors: Hoshina Hiromichi , Skvortsov Dmitri , Slipchenko Mikhail N. , Sartakov Boris G. , Vilesov Andrey F.
Published: August 2015

This work reports on the study of the internal rotation of methane molecules in small clusters containing up to about five molecules. The clusters were assembled in helium droplets at T = 0.38 K by successive capture of single methane molecules and studied by infrared laser spectroscopy of the fundamental CH4 ν3 vibration around 3030 cm−1. The spectra demonstrate well resolved structure due to internal rotation of the constituent molecules in the clusters. The most resolved spectrum for the dimers shows characteristic splitting of the lines due to anisotropic intermolecular interaction. The magnitude of the splitting is found to be in a good quantitative agreement with the recent theoretical anisotropic intermolecular potentials.
Bi-national research and education cooperation in the U.S.-China EcoPartnership for Environmental Sustainability
Authors: Filley Timothy R. , Li Meiling , Zhuang Jie , Yu Guirui , Sayler Gary , Ouyang Zhiyun , Han Xingguo , Zhang Xudong , Jiang Guibin , Zhou Chenghu , Wang Fan , Bickham John W.
Published: August 2015

The U.S.-China EcoPartnership for Environmental Sustainability (USCEES), one of 30 EcoPartnerships, was established within the U.S.-China Strategic Economic Dialogue framework in May 2011 by a joint agreement between the U.S. Department of State and China's National Development and Reform Commission. The USCEES has the goal of fostering bi-national research innovation, communication, and entrepreneurship to address the interconnected challenges of environmental, social, and economic sustainability. Research and education programs within the USCEES are focused on understanding current and past degradation of natural resources, investigating the drivers, impacts, and mitigation of global climate change, and assessing options for sustainable use of natural resources. Although both the U.S. and China have embraced a future based on science, technology, and innovation, our bi-national framework acknowledges that these two nations have vastly different cultural, political, and demographic legacies that could pose distinct challenges to uniform solutions or mandated collaborative networks. The peer-to-peer connections that drive the research component of the USCEES program are promoted and initiated from the ground up; they are based on the voluntary participation of scientists and engineers who are fascinated by the intellectual challenge of solving complex problems of inherent interest to them. Herein, we present highlights of USCEES activities that describe our efforts to discover, incubate, and nurture U.S.-China research collaborations to meet our collective goals. We discuss our pilot programs that are designed to highlight university facilities, resources, and technologies for tech transfer and licensing with an environmental solutions-oriented direction. Additionally, programs to promote cross-EcoPartnership collaborations are discussed.
“Plug-and-Play” potentials: Investigating quantum effects in (H2)2–Li+–benzene
Authors: D’Arcy Jordan H. , Kolmann Stephen J. , Jordan Meredith J. T.
Published: August 2015

Quantum and anharmonic effects are investigated in (H2)2–Li+–benzene, a model for hydrogen adsorption in metal-organic frameworks and carbon-based materials, using rigid-body diffusion Monte Carlo (RBDMC) simulations. The potential-energy surface (PES) is calculated as a modified Shepard interpolation of M05-2X/6-311+G(2df,p) electronic structure data. The RBDMC simulations yield zero-point energies (ZPE) and probability density histograms that describe the ground-state nuclear wavefunction. Binding a second H2 molecule to the H2–Li+–benzene complex increases the ZPE of the system by 5.6 kJ mol−1 to 17.6 kJ mol−1. This ZPE is 42% of the total electronic binding energy of (H2)2–Li+–benzene and cannot be neglected. Our best estimate of the 0 K binding enthalpy of the second H2 to H2–Li+–benzene is 7.7 kJ mol−1, compared to 12.4 kJ mol−1 for the first H2 molecule. Anharmonicity is found to be even more important when a second (and subsequent) H2 molecule is adsorbed; use of harmonic ZPEs results in significant error in the 0 K binding enthalpy. Probability density histograms reveal that the two H2 molecules are found at larger distance from the Li+ ion and are more confined in the θ coordinate than in H2–Li+–benzene. They also show that both H2 molecules are delocalized in the azimuthal coordinate, ϕ. That is, adding a second H2 molecule is insufficient to localize the wavefunction in ϕ. Two fragment-based (H2)2–Li+–benzene PESs are developed. These use a modified Shepard interpolation for the Li+–benzene and H2–Li+–benzene fragments, and either modified Shepard interpolation or a cubic spline to model the H2–H2 interaction. Because of the neglect of three-body H2, H2, Li+ terms, both fragment PESs lead to overbinding of the second H2 molecule by 1.5 kJ mol−1. Probability density histograms, however, indicate that the wavefunctions for the two H2 molecules are effectively identical on the “full” and fragment PESs. This suggests that the 1.5 kJ mol−1 error is systematic over the regions of configuration space explored by our simulations. Notwithstanding this, modified Shepard interpolation of the weak H2–H2 interaction is problematic and we obtain more accurate results, at considerably lower computational cost, using a cubic spline interpolation. Indeed, the ZPE of the fragment-with-spline PES is identical, within error, to the ZPE of the full PES. This fragmentation scheme therefore provides an accurate and inexpensive method to study higher hydrogen loading in this and similar systems.
Epitaxial lift-off for solid-state cavity quantum electrodynamics
Authors: Greuter Lukas , Najer Daniel , Kuhlmann Andreas V. , Valentin Sascha R. , Ludwig Arne , Wieck Andreas D. , Starosielec Sebastian , Warburton Richard J.
Published: August 2015

We demonstrate an approach to incorporate self-assembled quantum dots into a Fabry-Pérot-like microcavity. Thereby, a 3λ/4 GaAs layer containing quantum dots is epitaxially removed and attached by van der Waals bonding to one of the microcavity mirrors. We reach a finesse as high as 4100 with this configuration limited by the reflectivity of the dielectric mirrors and not by scattering at the semiconductor-mirror interface, demonstrating that the epitaxial lift-off procedure is a promising procedure for cavity quantum electrodynamics in the solid state. As a first step in this direction, we demonstrate a clear cavity-quantum dot interaction in the weak coupling regime with a Purcell factor in the order of 3. Estimations of the coupling strength via the Purcell factor suggest that we are close to the strong coupling regime.
Boundary conditions at the walls with thermionic electron emission in two temperature modeling of “thermal” plasmas
Authors: Pekker Leonid , Hussary Nakhleh
Published: August 2015

In this paper, we propose new boundary conditions for the electric potential, the electron energy equation, and the energy equation for heavy particles (ions and neutrals) at the hot walls with thermionic electron emission for two-temperature thermal arc models. The derived boundary conditions assume that the walls are made from refractory metals and, consequently, the erosion of the wall is small and can be neglected. In these boundary conditions, the plasma sheath formed at the electrode is viewed as the interface between the plasma and the wall. The derived boundary conditions allow the calculation of the heat flux to the walls from the plasma. This allows the calculation of the thermionic electron current that makes the model of electrode-plasma interaction self-consistent.
Vasyliunas–Cairns distribution function for space plasma species
Authors: Abid A. A. , Ali S. , Du J. , Mamun A. A.
Published: August 2015

A more generalized form of non-Maxwellian distribution function (that can be named as Vasyliunas–Cairns distribution function) is introduced. Its basic properties are numerically analyzed by the variation of two important parameters, namely, α (which shows the amount of energetic particles present in the plasma system) and κ (which shows the superthermality of the plasma species). It has been observed that (i) for α→0 (κ→∞), the Vasyliunas–Cairns distribution function reduces to the Vasyliunas or κ (Cairns or nonthermal) distribution function; (ii) for α→0 and κ→∞, it reduces to the Maxwellian distribution function; and (iii) the effect of the parameter α (κ) significantly modifies the basic properties of the Vasyliunas (Cairns) distribution function. The applications of this generalized non-Maxwellian distribution function (Vasyliunas–Cairns distribution function) in different space plasma situations are briefly discussed.
New complex function space related to both entangled state representation and spin coherent state
Authors: Lv Cui-hong , Fan Hong-yi
Published: August 2015

A new complex function space whose basis is the single-variable Hermite polynomial H2jξ*+τξ2τ is constructed, which is related to both entangled state representation and spin coherent state in Schwinger bosonic realization. New binomial theorem involving two-variable Hermite polynomial is derived, which helps to constitute the new complex function space. We also present a new integration transformation of the basis H2jξ*+τξ2τ with its reciprocal transformation which is useful to deriving some operator identities.
Energy conversion and momentum coupling of the sub-kJ laser ablation of aluminum in air atmosphere
Authors: Mori Koichi , Maruyama Ryo , Shimamura Kohei
Published: August 2015

Energy conversion and momentum coupling using nano-second 1-μm-wavelength pulse laser irradiation on an aluminum target were measured in air and nitrogen gas atmospheres over a wide range of laser pulse energies from sub-J to sub-kJ. From the expansion rate of the shock wave, the blast-wave energy conversion efficiency, ηbw, was deduced as 0.59 ± 0.02 in the air atmosphere at an ambient pressure from 30 to 101 kPa for a constant laser fluence at 115 J/cm2. Moreover, the momentum coupling of a circular disk target was formulated uniquely as a function of the dimensionless shock-wave radius and the ratio of the laser spot radius to the disk radius, while ηbw could be approximated as constant for the laser fluence from 4.7 to 4.1 kJ/cm2, and the ambient pressure from 0.1 to 101 kPa.
On the use of different coordinate systems in mechanochemical force analyses
Authors: Stauch Tim , Dreuw Andreas
Published: August 2015

Force analyses are crucial for a comprehensive understanding of mechanochemical processes. The choice of coordinate system in these kinds of analyses is a nontrivial task that determines the quality and validity of the obtained results. Here, we study the suitability of different sets of coordinates for mechanical force analyses, i.e., normal modes, delocalized internal, redundant internal, and Z-matrix coordinates. After discussing the theoretical foundations of force analyses using different coordinate systems, we investigate a number of test molecules. We show that normal modes and Z-matrix coordinates deliver useful results only if certain requirements are fulfilled and that only redundant internal coordinates yield meaningful results in all cases.
Energy error bars in direct configuration interaction iteration sequence
Authors: Tóth Zsuzsanna , Szabados Ágnes
Published: August 2015

A computational scheme for approximate lower bound to eigenvalues of linear operators is elaborated, based on Löwdin’s bracketing function. Implementation in direct full configuration interaction algorithm is presented, generating essentially just input–output increase. While strict lower bound property is lost due to approximations, test calculations result lower bounds of the same order of magnitude, as the usual upper bound, provided by the expectation value. Difference of upper and lower bounds gives an error bar, characterizing the wavefunction at the given iteration step.
Auxiliary matrix formalism for interaction representation transformations, optimal control, and spin relaxation theories
Authors: Goodwin D. L. , Kuprov Ilya
Published: August 2015

Auxiliary matrix exponential method is used to derive simple and numerically efficient general expressions for the following, historically rather cumbersome, and hard to compute, theoretical methods: (1) average Hamiltonian theory following interaction representation transformations; (2) Bloch-Redfield-Wangsness theory of nuclear and electron relaxation; (3) gradient ascent pulse engineering version of quantum optimal control theory. In the context of spin dynamics, the auxiliary matrix exponential method is more efficient than methods based on matrix factorizations and also exhibits more favourable complexity scaling with the dimension of the Hamiltonian matrix.
Conducting mechanisms of forming-free TiW/Cu2O/Cu memristive devices
Authors: Yan P. , Li Y. , Hui Y. J. , Zhong S. J. , Zhou Y. X. , Xu L. , Liu N. , Qian H. , Sun H. J. , Miao X. S.
Published: August 2015

P-type Cu2O is a promising CMOS-compatible candidate to fabricate memristive devices for next-generation memory, logic and neuromorphic computing. In this letter, the microscopic switching and conducting mechanisms in TiW/Cu2O/Cu memristive devices have been thoroughly investigated. The bipolar resistive switching behaviors without an electro-forming process are ascribed to the formation and rupture of the conducting filaments composed of copper vacancies. In the low resistive state, the transport of electrons in the filaments follows Mott's variable range hopping theory. When the devices switch back to high resistive state, the coexistence of Schottky emission at the Cu/Cu2O interface and electron hopping between the residual filaments is found to dominate the conducting process. Our results will contribute to the further understanding and optimization of p-type memristive materials.
Local uniaxial tensile strain in germanium of up to 4% induced by SiGe epitaxial nanostructures
Authors: Bollani Monica , Chrastina Daniel , Gagliano Luca , Rossetto Lidia , Scopece Daniele , Barget Michael , Mondiali Valeria , Frigerio Jacopo , Lodari Mario , Pezzoli Fabio , Montalenti Francesco , Bonera Emiliano
Published: August 2015

We show that a relatively simple top-down fabrication can be used to locally deform germanium in order to achieve uniaxial tensile strain of up to 4%. Such high strain values are theoretically predicted to transform germanium from an indirect to a direct gap semiconductor. These values of strain were obtained by control of the perimetral forces exerted by epitaxial SiGe nanostructures acting as stressors. These highly strained regions can be used to control the band structure of silicon-integrated germanium epilayers.
Electrodynamic boundary conditions for planar arrays of thin magnetic elements
Authors: Lisenkov Ivan , Tyberkevych Vasyl , Nikitov Sergei , Slavin Andrei
Published: August 2015

Approximate electrodynamic boundary conditions are derived for an array of dipolarly coupled magnetic elements. It is assumed that the elements' thickness is small compared to the wavelength of an electromagnetic wave in a free space. The boundary conditions relate electric and magnetic fields existing at the top and bottom sides of the array through the averaged uniform dynamic magnetization of the array. This dynamic magnetization is determined by the collective dynamic eigen-excitations (spin wave modes) of the array and is found using the external magnetic susceptibility tensor. The problem of oblique scattering of a plane electromagnetic wave on the array is considered to illustrate the use of the derived boundary conditions.
Spin reversal and ferroelectricity in perovskite Dy0.7Sr0.3MnO3 and Dy0.6Sr0.4MnO3
Authors: Jin Y. , Cui X. P. , Cheng J. A. , Cao S. X. , Ren W. , Zhang J. C.
Published: August 2015

Multiferroic materials which simultaneously exhibit electric polarization and magnetism have attracted more and more attention due to their novel physical properties and promising applications. Here, we report the magnetic and ferroelectric properties of single phase perovskite manganites Dy0.7Sr0.3MnO3 and Dy0.6Sr0.4MnO3 by varying temperature and magnetic field. Our results reveal that there exist spin reversal and strong antiferromagnetic pinning effects in both compounds, as well as negative magnetization in Dy0.6Sr0.4MnO3. Moreover, upon Sr-doping, spontaneous electric polarizations have been observed and the maximum polarization value of Dy0.7Sr0.3MnO3 is about 1000 μC/m2 while Dy0.6Sr0.4MnO3 reaches to 2000 μC/m2. The onset of the ferroelectric transition temperature is enhanced to be around 60 K. Our results indicate that the antiferromagnetic coupling is relevant to the ferroelectric properties of these fascinating multiferroic systems.
Suppression of the antiferroelectric phase during polarization cycling of an induced ferroelectric phase
Authors: Liu Xiaoming , Tan Xiaoli
Published: August 2015

The ceramic Pb0.99Nb0.02[(Zr0.57Sn0.43)0.92Ti0.08]0.98O3 can exist in either an antiferroelectric or a ferroelectric phase at room temperature, depending on the thermal and electrical history. The antiferroelectric phase can be partially recovered from the induced ferroelectric phase when the applied field reverses polarity. Therefore, polarization cycling of the ferroelectric phase in the ceramic under bipolar fields at room temperature is accompanied with repeated phase transitions. In this letter, the stability of the recovered antiferroelectric phase upon electrical cycling of the ceramic is investigated. Ex-situ X-ray diffraction reveals that bipolar cycling suppresses the antiferroelectric phase; this is indirectly supported by piezoelectric coefficient d33 measurements. It is speculated that the accumulated charged point defects during polarization cycling stabilize the polar ferroelectric phase. The findings presented are important to the fundamental studies of electric fatigue and field-induced phase transitions in ferroelectrics.
Development of a prototype Open-close positron emission tomography system
Authors: Yamamoto Seiichi , Okumura Satoshi , Watabe Tadashi , Ikeda Hayato , Kanai Yasukazu , Toshito Toshiyuki , Komori Masataka , Ogata Yoshimune , Kato Katsuhiko , Hatazawa Jun
Published: August 2015

We developed a prototype positron emission tomography (PET) system based on a new concept called Open-close PET, which has two modes: open and close-modes. In the open-mode, the detector ring is separated into two halved rings and subject is imaged with the open space and projection image is formed. In the close-mode, the detector ring is closed to be a regular circular ring, and the subject can be imaged without an open space, and so reconstructed images can be made without artifacts. The block detector of the Open-close PET system consists of two scintillator blocks that use two types of gadolinium orthosilicate (GSO) scintillators with different decay times, angled optical fiber-based image guides, and a flat panel photomultiplier tube. The GSO pixel size was 1.6 × 2.4 × 7 mm and 8 mm for fast (35 ns) and slow (60 ns) GSOs, respectively. These GSOs were arranged into an 11 × 15 matrix and optically coupled in the depth direction to form a depth-of-interaction detector. The angled optical fiber-based image guides were used to arrange the two scintillator blocks at 22.5° so that they can be arranged in a hexadecagonal shape with eight block detectors to simplify the reconstruction algorithm. The detector ring was divided into two halves to realize the open-mode and set on a mechanical stand with which the distance between the two parts can be manually changed. The spatial resolution in the close-mode was 2.4-mm FWHM, and the sensitivity was 1.7% at the center of the field-of-view. In both the close- and open-modes, we made sagittal (y-z plane) projection images between the two halved detector rings. We obtained reconstructed and projection images of 18F-NaF rat studies and proton-irradiated phantom images. These results indicate that our developed Open-close PET is useful for some applications such as proton therapy as well as other applications such as molecular imaging.
Growth and structure of ultrathin cerium oxide films on Rh(111)
Authors: Chan Lap Hong , Yuhara Junji
Published: August 2015

The geometric structure of ultra-thin cerium oxide films on Rh(111), prepared by annealing the metallic cerium films at a very low coverage between 0.3 and 1.5 monolayers in an oxygen atmosphere, is investigated using scanning tunneling microscopy (STM), low-energy electron diffraction (LEED), X-ray photoelectron spectroscopy, and density functional theory (DFT) calculations. The STM image and LEED pattern indicate that cerium oxide films epitaxially grown as ordered CeO2(111) layers aligned to the 110 azimuthal direction of Rh(111). The in-plane lattice parameter measured from the LEED pattern appears to be contracted with respect to the bulk ceria lattice. The measured ratio Ce:O for two-trilayer cerium oxide film is 1.96:1, which is close to the stoichiometric ratio. The simulated STM image on the basis of DFT+U calculations is in good agreement with the experimental STM images.