bluuebunny/crossref_metadata_2025 huggingface dataset:
Constructing organic superacids from superhalogens is a rational route as verified by DFT calculations
Authors: Zhou Fu-Qiang , Zhao Ru-Fang , Li Jin-Feng , Xu Wen-Hua , Li Chao-Chao , Luo Lan , Li Jian-Li , Yin Bing
Published: January 2019

The construction route of organic superacids from the combination of organic superhalogens and protons is verified to be a rational one based on a systematic theoretical study covering different planar conjugated backbones, e.g., [C5H5]− and [BC5H6]−, and electron-withdrawing substituents, e.g., –F, –CN and –NO2.
Water absorption by deep eutectic solvents
Authors: Chen Yu , Yu Dongkun , Chen Wenjun , Fu Li , Mu Tiancheng
Published: January 2019

Deep eutectic solvents are found to be highly hygroscopic when exposed to the atmosphere.
Crack propagation in graphene monolayer under tear loading
Authors: Ye Shijia , Cai Yang , Liu Xiaoyi , Yao Xiaohu , Luo Sheng-Nian
Published: January 2019

Crack propagation in graphene monolayer under tear loading is investigated via an energy-based analytical model and molecular dynamics (MD) simulations.
Biaryl synthesis with arenediazonium salts: cross-coupling, CH-arylation and annulation reactions
Authors: Felpin François-Xavier , Sengupta Saumitra
Published: January 2019

Arenediazonium salts are versatile synthons involved in various transformations for the construction of biaryl moieties.
Robust ultrafine ruthenium nanoparticles enabled by covalent organic gel precursor for selective reduction of nitrobenzene in water
Authors: Zhong Hong , Gong Yaqiong , Liu Wenhui , Zhang Bingbing , Hu Shuangqi , Wang Ruihu
Published: January 2019

Ultrafine metal nanoparticles were acquired through solid-state pyrolysis of a covalent organic gel containing metal ions. The unprecedented catalytic performance in terms of stability and reusability was displayed in the selective reduction of nitroarenes.
Lactulose synergizes with CpG-ODN to modulate epithelial and immune cells cross talk
Authors: Mukherjee R. , van de. Kaa M. , Garssen J. , Pieters R. J. , Kraneveld A. D. , Willemsen L. E. M.
Published: January 2019

Apart from being a prebiotic and laxative, lactulose has direct immunomodulatory effects.
Heterogeneous copper-catalyzed direct reduction of C-glycosidic enones to saturated alcohols in water
Authors: Petitjean L. , de Winter T. M. , Petrovic P. V. , Coish P. , Hitce J. , Moreau M. , Bordier T. , Erythropel H. C. , Anastas P. T.
Published: January 2019

Heterogeneous copper-catalysed full reduction of enones in a single procedure providing a library of C-glycosidic saturated alcohols.
Highly efficient hydrogenation of levulinic acid into 2-methyltetrahydrofuran over Ni–Cu/Al2O3–ZrO2bifunctional catalysts
Authors: Xie Zhenbing , Chen Bingfeng , Wu Haoran , Liu Mingyang , Liu Huizhen , Zhang Jianling , Yang Guanying , Han Buxing
Published: January 2019

High-performance bifunctional catalysts (Ni–Cu/Al2O3–ZrO2) have been investigated in the selective hydrogenolysis of levulinic acid into 2-methyltetrahydrofuran.
Ultra-high capacity microfluidic trapping of giant vesicles for high-throughput membrane studies
Authors: Yandrapalli Naresh , Robinson Tom
Published: January 2019

A high-capacity microfluidic platform designed to capture tens of thousands of giant vesicles for high-throughput membrane analysis.
In situ formation and superior lithium storage properties of tentacle-like ZnO@NC@CNTs composites
Authors: Wang Ying , Fan Shijia , Liao Fang , Zheng Xinshi , Huang Zhenguo , Wang Yijing , Han Xiaopeng
Published: January 2019

A novel structure of double carbon coated tentacle-like ZnO composite has been synthesized, which delivers remarkable Li+ storage properties.
Effect of asymmetric modification on perylene derivative molecule self-assembly structures
Authors: Liu Xiaoping , Xue Lingwei , Liang Minghui , Tan Keyan , Deng Ke , Ge Guanglu , Jiang Peng
Published: January 2019

This paper shows how the number and position of intermolecular hydrogen bonds affect achiral and chiral SAM structures.
Quantification of cellular associated graphene and induced surface receptor responses
Authors: Nima Zeid A. , Vang Kieng Bao , Nedosekin Dmitry , Kannarpady Ganesh , Saini Viney , Bourdo Shawn E. , Majeed Waqar , Watanabe Fumiya , Darrigues Emilie , Alghazali Karrer M. , Alawajji Raad A. , Petibone Dayton , Ali Syed , Biris Alexandru R. , Casciano Daniel , Ghosh Anindya , Salamo Gregory , Zharov Vladimir , Biris Alexandru S.
Published: January 2019

The use of graphene for biomedical and other applications involving humans is growing and shows practical promise.
Quantum 3D thermal imaging at the micro–nanoscale
Authors: Yang Jun , Li Ben Q. , Li Rongheng , Mei Xuesong
Published: January 2019

A new principle for 3D quantum thermal imaging at nanometer level is proposed to solve common problem of cell/particle temperature measurement and tracking. The proposed principle will provide new research ideas and advanced research tools for clarifying phenomena related to life activities and dynamic properties of nanoparticles, expected to promote innovation of materials science and life science.
Correction: Bioaccumulation of polystyrene nanoplastics and their effect on the toxicity of Au ions in zebrafish embryos
Authors: Lee Wang Sik , Cho Hyun-Ju , Kim Eungwang , Huh Yang Hoon , Kim Hyo-Jeong , Kim Bongsoo , Kang Taejoon , Lee Jeong-Soo , Jeong Jinyoung
Published: January 2019

Correction for ‘Bioaccumulation of polystyrene nanoplastics and their effect on the toxicity of Au ions in zebrafish embryos’ by Wang Sik Lee et al., Nanoscale, 2019, DOI: 10.1039/c8nr09321k.
Luminescent solar concentrators: boosted optical efficiency by polymer dielectric mirrors
Authors: Iasilli G. , Francischello R. , Lova P. , Silvano S. , Surace A. , Pesce G. , Alloisio M. , Patrini M. , Shimizu M. , Comoretto D. , Pucci A.
Published: January 2019

High dielectric contrast polymer dielectric mirrors are used to recycle non-absorbed photons in organic luminescent solar concentrators. A 10% increase in the concentrator optical efficiency is found and retained upon doubling its size paving the way to lightweight and cheap building integrated photovoltaic systems.
Iodine-promoted one pot reaction of pyridin-2-amine with arylmethyl ketone and selenosulfonate: synthesis of 3-(alkylselanyl)-2-arylimidazo[1,2-a]pyridine under transition-metal free conditions
Authors: Jiang Nan , Fang Yi , Fang Yue , Wang Shun-Yi , Ji Shun-Jun
Published: January 2019

A new efficient approach for the I2 promoted selenium functionalization of in situ generated imidazoheterocycles utilizing aliphatic selenosulfonate as the selenium source under transition metal-free conditions is developed.
Correction: Improved lateral heat spreading performance for polyvinylidene fluoride composite film comprising silver nanowire in light-emitting diode
Authors: Li Zhao , Zhang Li , Qi Rong , Xie Fan , Qi Shuhua
Published: January 2019

Correction for ‘Improved lateral heat spreading performance for polyvinylidene fluoride composite film comprising silver nanowire in light-emitting diode’ by Zhao Li et al., RSC Adv., 2016, 6, 35844–35891.
A novel polymer donor based on dithieno[2,3-d:2′,3′-d′′]benzo[1,2-b:4,5-b′]dithiophene for highly efficient polymer solar cells
Authors: Huang Jiaming , Peng Ruixiang , Xie Lingchao , Song Wei , Hong Ling , Chen Sanhui , Wei Qiang , Ge Ziyi
Published: January 2019

A novel polymer was used as the donor material in organic solar cells to achieve the best photovoltaic performance based on DTBDT.
Hybrid particles derived from alendronate and bioactive glass for treatment of osteoporotic bone defects
Authors: Diba Mani , Camargo Winston A. , Zinkevich Tatiana , Grünewald Alina , Detsch Rainer , Kabiri Yoones , Kentgens Arno P. M. , Boccaccini Aldo R. , van den Beucken Jeroen J. J. P. , Leeuwenburgh Sander C. G.
Published: January 2019

Novel hybrid particles are synthesized using alendronate and bioactive glass, which can stimulate regeneration of osteoporotic bone defects.
FBXL19-AS1 exerts oncogenic function by sponging miR-431-5p to regulate RAF1 expression in lung cancer
Authors: Jiang Qian , Cheng Li , Ma Daiyuan , Zhao Yanli
Published: January 2019

Lung cancer is the leading cause of cancer-related mortality worldwide, characterized by uncontrolled proliferation and metastasis of lung cancer cells. Tumor angiogenesis plays a key role in proliferation and metastasis in cancers, and is an essential component in microenvironment. It has been reported that long non-coding RNA FBXL19-AS1 plays an oncogenic role in colorectal cancer. However, the molecular mechanism of FBXL19-AS1 in lung cancer has not been fully elucidated. In the present study, we found that FBXL19-AS1 expression was up-regulated in lung cancer tissues and cell lines. FBXL19-AS1 knockdown inhibited cell proliferation, migration, invasion, and angiogenesis in lung cancer cells. Molecular mechanism exploration uncovered that FBXL19-AS1 acted as a molecular sponge of miR-431-5p and that RAF1 was a downstream target of miR-431-5p in lung cancer. Moreover, there was a negative association between miR-431-5p expression and FBXL19-AS1 or RAF1 expression in tumor tissues. Through rescue experiments, we discovered that overexpression of RAF1 partially rescued FBXL19-AS1 knockdown-mediated inhibition of angiogenesis and progression in lung cancer. Together, these results indicated that FBXL19-AS1 was involved in progression and angiogenesis in lung cancer by targeting miR-431-5p/RAF1 axis, which provided a new insight into the therapeutic strategies of lung cancer.
Flocking‐based cooperative autonomous driving using vehicle‐to‐everything communication
Authors: Park Y. , Kuk S. , Han S. , Lim S. , Kim H.
Published: January 2019

Current autonomous driving relies on sensors that can only observe the vehicles in the line of sight (LoS), rendering the driving decisions to hinge on the physical movements of the visible vehicles in proximity. Furthermore, it is practically impossible to sense their intentions. Consequently, driving decisions that account for non‐LoS vehicles and the intentions of neighbouring vehicles are hard to achieve. This Letter shows the potential of combining vehicular communication with autonomous driving. In particular, the authors show how vehicular communication can assist autonomous driving decision, with a case of a controller that mimics the flocking behaviours in nature.
Automatic directional masking technique for better sperm morphology segmentation and classification analysis
Authors: Ilhan H.O. , Serbes G. , Aydin N.
Published: January 2019

Male‐based factors have very critical effects in infertility. The determination of male factors is based on the semen analysis performed by multiple aspects such as motility, morphological and concentration. Normally, tests are applied by experts manually. Therefore, the results are highly subjective. Automation of analysis minimises the human factor. In this respect, a number of studies on the computerised semen analysis have been recently reported. One of the most important steps in computerised approaches is the region of interest extraction. In this Letter, a novel masking technique is introduced with the aim of better region of interest extraction, in which each sperm is individually analysed by head and tail specified stages. In this approach, wavelet‐based image enhancement techniques and gradient analysis are jointly utilised for finding the sperm orientation. Later, elliptic masks are employed for the sperm segmentation along this orientation. As the evaluation methods, firstly proposed technique's segmentation performance is assessed by visual inspection. Secondly, the k‐nearest neighbours (k‐NN) classification results of proposed approach's outputs are compared with the outputs of classical k‐means segmentation and also the raw images. Results indicate that 93.5% of all the sperms are correctly segmented by proposed masking approach and up to 13% increase is observed in k‐NN classification.
Circularly polarised antenna with wide harmonics suppression by two angled C‐shaped structures
Authors: Oh J.E. , Sung Y.
Published: January 2019

In this Letter, a circularly polarised (CP) antenna is proposed. The proposed antenna is realised by combining two angled C‐shaped structures. By setting different widths (WL and WR) for the left and right angled C‐shaped structures, respectively, an asymmetric structure is obtained. Therefore, the proposed antenna exhibits CP characteristics. From repeated simulation results, the authors find that the optimum ratio WL: WR to make the proposed structure operate as a CP antenna is 5: 8. Moreover, the measured reflection coefficient is lower than −2.4 dB within a stopband up to 12 GHz. This means that wide harmonics suppression (up to the fifth harmonic) is successfully achieved.
Enabling on‐aircraft visible‐light communications in low‐light conditions
Authors: Tagliaferri D. , Capsoni C.
Published: January 2019

Visible‐light communications (VLCs) are emerging as a valid alternative to radio‐frequency systems for the provision of Internet connectivity to aircraft passengers through the LED reading lamps. In this Letter, the authors investigate the minimum required level of emitted flux in order to support the communication with the users' terminals. A VLC system employing 1 lm of flux is able to achieve an average per‐user capacity comparable with the one currently in use for 4G (6 bit/s/Hz) over an electrical bandwidth of 10 MHz, which is sufficient to support the latest multimedia services (40 Mb/s for Blu‐ray video streaming).
BBPD with wide input phase range
Authors: Kossel M. , Francese P. , Morf T. , Brändli M. , Khatri V. , Yonar S. , Dazzi M. , Khaddam‐Aljameh R.
Published: January 2019

Wireline communication circuits often include serialisers/deserialisers using multiphase signals for multiplexing or sampling. From a power efficiency viewpoint, configurations are desired in which a single differential clock at frequency f is distributed to decentralised multiphase generators as opposed to distribution at 2f with local frequency dividers. A bang–bang phase detector (BBPD) is presented for such a multiphase generator operated from 4 to 16 GHz. Owing to the 2‐octave frequency range, a wide input phase range is required for which the BBPD may not generate false locks. This is achieved by an implementation in which down pulses at the output of a fully symmetrical set/reset latch are stretched via pulse‐width extension circuitries. A sampling pulse generated from one of the input phases can then easily capture the extended down pulses across a wide input phase range to unambiguously indicate phase leading or phase lagging to the control logic of the multiphase generator. The proposed circuitry has been implemented in a 7 nm CMOS technology. A comparison to alternative BBPD approaches implemented in the same technology shows that the proposed architecture outperforms them in terms of achievable input phase range.
Dual‐band dual‐polarised microstrip antenna with improved inter‐port isolation
Authors: Chakrabarti S. , Chakraborty A.
Published: January 2019

This Letter presents the development of a dual linearly polarised microstrip antenna for S‐ and C‐band with improved isolation and bandwidth. The antenna is dual linearly polarised at each of the bands. The S‐band patch is proximity coupled to two orthogonal feed lines, whereas the C‐band patches are aperture coupled to other two mutually orthogonal feed lines. The antenna results in an impedance bandwidth ≥ 3.65% with an isolation ≥ 26 dB at the S‐band ports. At the C‐band ports, it also displays an isolation ≥ 45 dB over the entire operating bandwidth of ≥ 21%. All these results are improved compared to the earlier reported investigations.
Generalised current and voltage shaping method via modified d–q transformation for the torque harmonics correction in PMSMs
Authors: De Soricellis Milo , Rapp Holger
Published: January 2019

This study deals with a novel control strategy for permanent magnet synchronous machines (PMSMs) to incorporate harmonics compensation features within the current controller, maintaining the integrity of the reference tracking performances. The authors’ application in this context is devoted to the improvement of the torque produced by a PMSM, in particular, it is proposed the effective reduction of the undesired harmonic content of the torque due to the non‐sinusoidal spatial distribution of the flux density in the air‐gap. With the knowledge of the back electro‐magnetic force shape, the determination of the current waveforms necessary to produce a smooth torque is enabled and via model‐based considerations, the corresponding required voltage waveforms are computed. Subsequently, the reasoning is extended to the flux weakening operation of the machine. Finally, it is applied to the more common case of interior PMSMs, which additionally exhibit a reluctance torque component. The analytical solutions found are used in place of the classical αβ/dq Park‐transformation, thus impressing the appropriate current waveforms to the machine without modifying any functionality within the main current controller. The effectiveness of the proposed strategy is verified by experimental results.
Possible depletion of metals into dust grains in the core of the Centaurus cluster of galaxies
Authors: Lakhchaura K. , Mernier F. , Werner N.
Published: January 2019

We present azimuthally averaged metal abundance profiles from a full, comprehensive, and conservative re-analysis of the deep (∼800 ks total net exposure)Chandra/ACIS-S observation of the Centaurus cluster core (NGC 4696). After carefully checking various sources of systematic uncertainties, including the choice of the spectral deprojection method, assumptions about the temperature structure of the gas, and uncertainties in the continuum modeling, we confirm the existence of a central drop in the abundances of the “reactive” elements Fe, Si, S, Mg, and Ca, withinr≲10 kpc. The same drops are also found when analyzing theXMM-Newton/EPIC data (∼150 ks). Adopting our most conservative approach, we find that, unlike the central drops seen for Fe, Si, S, Mg and Ca, the abundance of the “nonreactive” element Ar is fully consistent with showing no central drop. This is further confirmed by the significant (> 3σ) central radial increase of the Ar/Fe ratio. Our results corroborate the previously proposed “dust depletion scenario”, in which central metal abundance drops are explained by the deposition of a significant fraction of centrally cooled reactive metals into dust grains present in the central regions of the Centaurus cluster. This is also supported by the previous findings that the extent of the metal abundance drops in NGC 4696 broadly coincides with the infrared dust emission.
Growth rates of ITG modes in the presence of flow shear
Authors: Dagnelie V. I. , Citrin J. , Jenko F. , Pueschel M. J. , Görler T. , Told D. , Doerk H.
Published: January 2019

Plasma microinstabilities in toroidal magnetic confinement devices can be driven unstable by a radial ion temperature gradient and stabilized by rotational flow shear. In this study, we argue that these nonlinear dynamics can be captured by the linear stabilization of Floquet modes. To that end, we propose a novel method (the τAC method) to calculate growth rates by averaging over linear Floquet modes. The τAC method is compared to nonlinear and other linear approaches and is shown to work well at low parallel velocity gradient drive. As such, the method provides a promising approach to explore the parameter dependencies of flow shear stabilization.
Efficiency signal conversion parameter to evaluate astigmatic femtosecond-optical parametric oscillator cavities
Authors: Castro-Olvera G. , Garduño-Mejía J. , Rosete-Aguilar M.
Published: January 2019

In this work, we define the efficiency signal conversion numerical parameter, Veff, useful to evaluate the operation efficiency of femtosecond-Optical Parametric Oscillator (fs-OPO) cavities considering the astigmatism effect. For the validation of the Veff, we have performed experimental measurements. We present different high efficiency home-made singly resonant fs-OPO cavities, with signal tuneability from 1.1 µm to 1.6 µm based on a 0.5 mm Periodically Poled Lithium Niobate doped with MgO (MgO:PPLN) crystal. We have also defined the pump energy threshold per crystal unit length, ζp,th. Pump threshold, achieved by following the Veff, was 142 mW at 810 nm, and ζp,th = 2.10 nJ/mm, the lowest value, in comparison with other studies. The Veff is based on an ABCD matrix Gaussian beam propagation method, which calculates the mode coupling between the pump and signal beams along the crystal under different cavity configurations taking into account the astigmatism. The model was compared and tested with 3 different experimental singly resonant fs-OPO ring cavity configurations that we have defined as single-folded, two-folded, and direct-pump cavity.
Interfacial electric field and spin-orbitronic properties of heavy-metal/CoFe bilayers
Authors: Zeng Minggang , Chen BingJin , Lim Sze Ter
Published: January 2019

Spin-orbit coupling (SOC) has become an important ingredient in magnetic storage devices for the realization of electrical control over magnetic dynamics via spin-orbit torque (SOT). An intriguing platform in controlling spin-orbit properties is the interface between a heavy metal (HM) and a CoFe free magnet. In this paper, we investigate the interfacial electric field and spin-orbitronic properties in HM/CoFe (HM = Pd, Ag, Ir, Pt, Au, Ta, and W) bilayers using first-principles calculations. We calculate the interfacial electric field and spin-orbit moments at the interfacial heavy atom and find that orbital magnetic moments in these heavy atoms are nearly proportional to their spin moments. Furthermore, we compare the SOC strength at the interfacial heavy atom with its bulk value and reveal a linear correlation between the variation of SOC strength and the amplitude of the interfacial electric field. Our results suggest that the HM/CoFe interface plays an essential role in tuning the SOC effect and can be exploited to design SOT-based spin-orbitronic devices.
Development of the perturbation theory using polynomial solutions
Authors: Maiz F.
Published: January 2019

The number of quantum systems for which the stationary Schrodinger equation is exactly solvable is very limited. These systems constitute the basic elements of the quantum theory of perturbation. The exact polynomial solutions for real quantum potential systems provided by the use of Lagrange interpolation allows further development of the quantum perturbation theory. In fact, the first order of correction for the value of the energy appears to be sufficient since the chosen perturbation Hamiltonian is very small or even negligible compared to the main Hamiltonian. Here, we use the perturbation theory to derive polynomial solutions, and we then find that our approximated results agree very well with previous published or numerically achieved ones. We believe that this study is an operational tool for the verification and improvement of numerical and approximate methods.
An articulated finger driven by single-mode piezoelectric actuator for compact and high-precision robot hand
Authors: Chen Di , Li Xinjian , Jin Jiamei , Ruan Chongyuan
Published: January 2019

In this paper, a novel finger driven by single-mode piezoelectric actuator for a compact and high-precision robot hand is proposed. Three piezoelectric actuators are articulated by two sets of connecting elements to form the finger. The finger utilizes a single model of the piezoelectric actuator to generate friction force to drive the joint. Without the difficulty to adjust for the coincidence of modal frequencies, the design of the piezoelectric actuator has fewer restrictions on size and structure; thus, the finger has a compact structure. The bidirectional motion of the joint is achieved by changing the temporal phase difference of two excitation signals applied on the two adjacent piezoelectric actuators. In addition, due to the characteristics of piezoelectric drive, such as power cut self-locking and quick response, the finger has a high resolution to realize micromanipulation for high precise movement. In our design, the first order longitudinal vibration mode of the piezoelectric actuator is used to generate the friction force. By using a finite element model, the geometric parameters of the piezoelectric actuator are obtained. A prototype of the finger is fabricated and experimentally investigated, the size (111 × 10 × 10 mm) is approximately 1.5 times that of a human middle finger, and the weight is 0.11 kg. The experimental results indicate that the angular speed of the prototype reaches 6.6 rad/s, the resolution is 20 mrad, and the startup and shutdown response times are 26 ms and 7 ms under a voltage of 400 Vpp, respectively. The fingertip force is 0.27 N under a voltage of 400 Vpp. The proposed finger has a compact size and simple structure with a high resolution (20 mrad).
Light-driven water oxidation by a dye-sensitized photoanode with a chromophore/catalyst assembly on a mesoporous double-shell electrode
Authors: Liu Qing , Wang Degao , Shan Bing , Sherman Benjamin D. , Marquard Seth L. , Eberhart Michael S. , Liu Meichuan , Li Chunhui , Meyer Thomas J.
Published: January 2019

A mesoporous atomic layer deposition (ALD) double-shell electrode, Al2O3 (insulating core)//ALD ZnO|ALD TiO2, on a fluorine-doped tin oxide (FTO) conducting substrate was explored for a photoanode assembly, FTO//Al2O3 (insulating core)//ALD ZnO|ALD TiO2|–chromophore–catalyst, for light-driven water oxidation. Photocurrent densities at photoanodes based on mesoporous ALD double-shell (ALD ZnO|ALD TiO2|) and ALD single-shell (ALD ZnO|, ALD TiO2|) electrodes were investigated for O2 evaluation by a generator–collector dual working electrode configuration. The high photocurrent densities obtained based on the mesoporous ALD ZnO|ALD TiO2 photoanode for O2 evolution arise from a significant barrier to back electron transfer (BET) by the optimized tunneling barrier in the structure with the built-in electric field at the ALD ZnO|ALD TiO2 interface. The charge recombination is thus largely decreased. In the films, BET following injection has been investigated through kinetic nanosecond transient absorption spectra, and the results of energy band analysis are used to derive insight into the internal electronic structure of the electrodes.
Effect of sodium addition and thermal annealing on second-order optical nonlinearity in thermally poled amorphous Ta2O5 thin films
Authors: Tong Amy S. K. , Bondu Flavie , Senthil Murugan G. , Wilkinson James S. , Dussauze Marc
Published: January 2019

We demonstrate second-order optical nonlinearity (SON) induced in amorphous tantalum pentoxide (Ta2O5) films by thermal poling. The effects of sodium addition and thermal annealing on the efficiency and stability of second harmonic generation (SHG) have been investigated. Maker fringe analysis has been used to quantify the poling-induced SON. χ(2) of 0.46 ± 0.02 pm/V and 0.34 ± 0.02  pm/V was achieved for sodium-containing and pure Ta2O5 films, respectively. Both the strength and the temporal stability of the induced nonlinearity are discussed with respect to the poling mechanisms and measured electrical conductivity. The lower density of uncombined charges of the Ta2O5 thin films is believed to play a role in the strength of SHG signal, and the rate of SHG decay decreases with thermal annealing.
A computational model for exploring particle acceleration during reconnection in macroscale systems
Authors: Drake J. F. , Arnold H. , Swisdak M. , Dahlin J. T.
Published: January 2019

A new computational model suitable for exploring the self-consistent production of energetic electrons during magnetic reconnection in macroscale systems is presented. The equations are based on the recent discovery that parallel electric fields are ineffective drivers of energetic particles during reconnection so that the kinetic scales which control the development of such fields can be ordered out of the equations. The resulting equations consist of a magnetohydrodynamic (MHD) backbone with the energetic component represented by macro-particles described by the guiding center equations. Crucially, the energetic component feeds back on the MHD equations so that the total energy of the MHD fluid and the energetic particles is conserved. The equations correctly describe the firehose instability, whose dynamics plays a key role in throttling reconnection and in controlling the spectra of energetic particles. The results of early tests of the model, including the propagation of Alfvén waves in a system with pressure anisotropy and the growth of firehose modes, establish that the basic algorithm is stable and produces reliable physics results in preparation for further benchmarking with particle-in-cell models of reconnection.
Exploring chemical speciation at electrified interfaces using detailed continuum models
Authors: Baskin Artem , Prendergast David
Published: January 2019

We present a local free-energy functional-based generic continuum model for material interfaces with a specific emphasis on electrified solid/liquid interfaces. The model enables a description of multicomponent phases at interfaces and includes the effects of specific non-electrostatic interactions (specific adsorption), ion size disparity, and the explicit presence of neutral species. In addition to the optimization of electrostatic, non-electrostatic, and steric forces, the model can be easily modified to explore the effects of other channels for equilibration, including local chemical transformations driven by equilibrium constants and electrochemical reactions driven by the electrode potential. In this way, we show that, upon accounting for these effects, local speciation in the vicinity of the interface can be drastically different from what is expected from restricted models and minor species (from the bulk perspective) may become dominant due to the effects of local pH. We evaluate the ionic contribution to the surface tension at the interface and show how this could impact the structure of air/liquid interfaces. On the same footing, an attempt to describe electrochemical metal dissolution is made. The model allows estimates of the mutual population of newly produced ions depending on their charge and size and could be useful for interpretation of electrochemical and spectroscopic measurements if the dissolution involves different metal ions (species). With these advances, the proposed model may be used as an ingredient within a hybrid ab initio-continuum methodology to model biased interfaces.
Effect of particle aggregation on thermal conductivity of nanofluids: Enhancement of phonon MFP
Authors: Song Dongxing , Jing Dengwei , Ma Weigang , Zhang Xing
Published: January 2019

Particle aggregation in nanofluids is a common phenomenon. Some studies indicated that aggregation can increase the thermal conductivity of nanofluids due to the formation of an “efficient heat channel,” while the underlying mechanism is still unclear. In this study, an effective medium model considering phonon scattering is applied to explore the effect of particle aggregation on nanofluid thermal conductivity. The aggregation is simulated by a diffusion-limit-cluster-aggregation model, where the effects of nanoparticle size, concentration, and number in a cluster on the aggregation structure are studied. Results show that nanoparticle aggregation can dramatically increase the thermal conductivity of nanofluids, and aggregation puts up stronger effects for the case of smaller nanoparticles and lower concentrations. The main mechanism is that the aggregation raises the phonon MFP in the solid phase, which further results in the thermal conductivity enhancement of nanoparticles.
Large dynamic range data acquisition system for time-domain electromagnetic interference (TDEMI) measurement receiver
Authors: Zeng Hao , Gao Jian , Ye Peng , Guo Lianping , Liao Ke
Published: January 2019

Electromagnetic interference (EMI) measurement is essential in wireless communications to avoid both performance degradation and serious fault failures. In this paper, we present the design of an acquisition system for a time-domain EMI measurement receiver intended for monitoring potential EMI. The platform consists of both hardware and software systems. The hardware system is constructed using a modular design method and contains a conditioning module, a data acquisition and processing module, and a clock generation module. The software system provides an interactive interface for device operation and offers an automatic sampling/processing procedure that is developed on a slot 0 controller. An additional outstanding feature of the proposed system is its high dynamic range. We propose a novel multi-stage architecture and a data reconstruction algorithm that are combined to achieve large dynamic range acquisition. The proposed acquisition architecture breaks through the dynamic range limitations of conventional analog-to-digital converters (ADCs) on a significant scale. The implemented system is able to capture an analog waveform with a 300 MHz bandwidth and a 1 GS/s sampling rate. The experimental results show that the maximum dynamic range achieved is 96.43 dB, which is far greater than the single ADC dynamic range of 52 dB.
Thickness dependence of dielectric and piezoelectric properties for alternating current electric-field-poled relaxor-PbTiO3 crystals
Authors: Qiu Chaorui , Liu Jinfeng , Li Fei , Xu Zhuo
Published: January 2019

Relaxor-PbTiO3 crystals possess ultrahigh piezoelectricity when compared with state-of-the-art Pb(Zr,Ti)O3 ceramics. Recently, even higher piezoelectricity is observed in alternating current electric-field-poled (AC-poled) crystals. This poling technique may benefit many piezoelectric materials and corresponding applications. The scaling effect is quite important for piezoelectric applications, since the operational frequency of devices is associated with the dimension of piezoelectric elements. Here, we investigated the thickness dependence of dielectric and piezoelectric properties for AC-poled relaxor-PbTiO3 crystals. Compared with the traditional poling method, the piezoelectric coefficient (d33) and dielectric permittivity (ɛT33/ɛ0) were found to be increased by 20%-30% via alternating current electric field poling (AC-poling). A weak scaling effect was observed for the samples with thickness above 200 μm. While, for 100-μm samples, the dielectric permittivity was only enhanced by 6%, and a clear degradation of properties was observed when the cycle of alternating current electric field is beyond three. These features are thought to be associated with the impacts of surface damages for thin samples. Of particular interest is that the coercive field was found to decrease during AC-poling, which should be considered for the design of piezoelectric devices. This work provides important information for AC-poled relaxor-PbTiO3 crystals and will benefit the piezoelectric applications using these crystals.
A large-aperture strip-grid beam splitter for partially combined two millimeter-wave diagnostics on Korea Superconducting Tokamak Advanced Research
Authors: Lee D. J. , Lee W. , Park H. K. , Kim T. G.
Published: January 2019

A large-aperture beam splitter has been developed for simultaneous operation of two millimeter-wave diagnostics employing different probe beams in the frequency and polarization, microwave imaging reflectometer (∼85 GHz X-mode), and collective scattering system (300 GHz O-mode), on the Korea Superconducting Tokamak Advanced Research device. The beam splitter was designed based on a polarizer concept (i.e., grid of metal strips on a thin dielectric sheet), and this can be an optimal solution for these two diagnostics. Fabrication of the strips with uniform sub-millimeter width and spacing on a large dielectric sheet was achieved with an etching technique, and the laboratory test results on the reflection and transmission ratio are in good agreement with design values.
Increase in the piezoelectric response of scandium-doped gallium nitride thin films sputtered using a metal interlayer for piezo MEMS
Authors: Uehara Masato , Mizuno Takaaki , Aida Yasuhiro , Yamada Hiroshi , Umeda Keiichi , Akiyama Morito
Published: January 2019

Wurtzite gallium nitride (GaN) has a polarity along the c-axis and piezoelectric properties the same as aluminum nitride. Since it has a high mechanical quality factor and high output sensitivity, it is expected to perform well in piezo micro-electro-mechanical system devices. This paper demonstrates that Hf and Mo interlayers enable the preparation of highly (001)-oriented GaN films via conventional sputtering at a low temperature (400 °C). The piezoelectric coefficient d33 of the prepared undoped GaN films is equivalent to that of a single-crystal GaN. Furthermore, the results demonstrate that the piezoelectric response of GaN films increases significantly when they are doped with scandium (Sc). Although this enhancement was predicted theoretically, the piezoelectric response of Sc-doped GaN films prepared on Hf and Mo interlayers has shown great improvement. Moreover, bulk acoustic wave resonators constructed using Sc-doped GaN films show a piezoelectric coupling factor that is three times larger than that of a single-crystal GaN.
Magnetoelectric couplings in high-density array of nanoscale Co/BiFeO3 multiferroic heterostructures
Authors: Zhong Xin , Tian Guo , Song Xiao , Wang Yadong , Yang Wenda , Li Peilian , Luo Qiuyuan , Hou Zhipeng , Fan Zhen , Chen Deyang , Qin Minghui , Zeng Min , Gao Xingsen , Liu Jun-Ming
Published: January 2019

We have systematically explored the magnetoelectric (ME) coupling effect of Co/BiFeO3 multiferroic heterostructured nanodot arrays, fabricated by the anodic aluminum oxide template method. Piezoresponse hysteresis loops of these nanodots demonstrate a significant enhancement of the ME coupling effect. More intriguingly, we have realized a magnetic domain transformation from an initial single-domain state to a vortex state by applying a regional or local voltage, and the single-domain state can be recovered by using an external in-plane magnetic field. Our results will guide the invention of high-density, energy-efficient, non-volatile multifunctional ME microdevices.
Brownian motion of skyrmion bubbles and its control by voltage applications
Authors: Nozaki Takayuki , Jibiki Yuma , Goto Minori , Tamura Eiiti , Nozaki Tomohiro , Kubota Hitoshi , Fukushima Akio , Yuasa Shinji , Suzuki Yoshishige
Published: January 2019

Magnetic skyrmions are expected to be promising candidates for information carriers in spintronic devices. In previous work, precise position control of skyrmions has been the main focus of attention for memory and logic applications. Here, with the aim of employing the thermally activated random walk of skyrmion bubbles for logical operations, i.e., token-based Brownian computing, we investigated the dynamics of skyrmion bubbles in W/FeB/Ir/MgO structures. In addition to the observation of Brownian motion of skyrmion bubbles, we demonstrated the electrical control of the diffusion constant by voltage applications. The developed technique would be useful for various kinds of skyrmion-based spintronic devices as well as Brownian computing.
Measurements of the momentum-dependence of plasmonic excitations in matter around 1 Mbar using an X-ray free electron laser
Authors: Preston T. R. , Appel K. , Brambrink E. , Chen B. , Fletcher L. B. , Fortmann-Grote C. , Glenzer S. H. , Granados E. , Göde S. , Konôpková Z. , Lee H. J. , Marquardt H. , McBride E. E. , Nagler B. , Nakatsutsumi M. , Sperling P. , Witte B. B. L. , Zastrau U.
Published: January 2019

We present measurements of the plasmon shift in shock-compressed matter as a function of momentum transfer beyond the Fermi wavevector using an X-ray Free Electron Laser. We eliminate the elastically scattered signal retaining only the inelastic plasmon signal. Our plasmon dispersion agrees with both the random phase approximation (RPA) and static Local Field Corrections (sLFC) for an electron gas at both zero and finite temperature. Further, we find the inclusion of electron-ion collisions through the Born-Mermin Approximation (BMA) to have no effect. Whilst we cannot distinguish between RPA and sLFC within our error bars, our data suggest that dynamic effects should be included for LFC and provide a route forward for higher resolution future measurements.
Reduced reverse gate leakage current for GaN HEMTs with 3 nm Al/40 nm SiN passivation layer
Authors: Zhang Sheng , Wei Ke , Ma Xiao-Hua , Hou Bin , Liu Guo-Guo , Zhang Yi-chuan , Wang Xin-Hua , Zheng Ying-Kui , Huang Sen , Li Yan-Kui , Lei Tian-Min , Liu Xin-Yu
Published: January 2019

An obvious increase in the gate leakage current has been commonly observed in GaN HEMTs, after Plasma-enhanced chemical vapor deposition (PECVD) SiN passivation has been observed to obviously increase. This paper presents an Al/SiN stack layer passivation structure. The high gate leakage current in GaN HEMTs caused by the PECVD SiN passivation is distinctly reduced by 2 to 3 orders of magnitude by introducing a thin Al layer. It is mainly attributed to the Al layer blocking and minimizing the damage for the (Al)GaN surface in the build-up of the luminance process of PECVD SiN and then reducing the surface trap density. TEM mapping and SRIM software simulation reveal that neither damage nor inter-diffusion is demonstrated at the Al/AlGaN interface, where a continuous crystalline region is observed. The moderate current collapse suppression and 32.8% improvement in VBR are achieved in GaN HEMTs with Al/SiN passivation.
Perspective: Nanoscopy of charge kinetics via terahertz fluctuation
Authors: Komiyama Susumu
Published: January 2019

A novel scanning microscope, which visualizes kinetics of charges by mapping ultrahigh frequency current fluctuation (15–30 THz), is described. This microscope, called the scanning noise microscope, scatters a fluctuating electromagnetic evanescent field on the sample surface with a sharp metal tip and detects the scattered field with an ultrahighly sensitive THz detector in a THz confocal microscope. This article describes the basic concept of the microscope, highlights the uniqueness and the general importance of the method, and demonstrates the powerfulness of the method by exemplifying experimental results made on (i) nanostructured metal layers in thermal equilibrium, (ii) narrow metal wires under non-uniform Joule heating, and (iii) operating GaAs nano-devices with non-local hot-electron energy dissipation in a highly non-equilibrium condition.
Fat-regulated adaptor protein Dlish binds the growth suppressor Expanded and controls its stability and ubiquitination
Authors: Wang Xing , Zhang Yifei , Blair Seth S.
Published: January 2019

Significance

To regulate the growth and size of organs, cells can use information from their neighbors to modify intracellular mediators of cell proliferation. The intracellular Hippo pathway is a widely utilized nexus for growth control in animals, but its regulation by extracellular signals is not fully understood. We here identify a pathway that regulates organ size in
Drosophila
, triggered by the transmembrane receptor, the giant protocadherin Fat. We show that the Fat-regulated SH3 domain adaptor protein Dlish binds to and reduces the stability of the growth suppressor Expanded, a known regulator of the Hippo pathway. The destabilization of Expanded by Dlish works in parallel to a previously established pathway in which Dlish increases levels of the growth-stimulating protein Dachs.
Type I interferon response impairs differentiation potential of pluripotent stem cells
Authors: Eggenberger Julie , Blanco-Melo Daniel , Panis Maryline , Brennand Kristen J. , tenOever Benjamin R.
Published: January 2019

Upon virus infection, pluripotent stem cells neither induce nor respond to canonical type I interferons (IFN-I). To better understand this biology, we characterized induced pluripotent stem cells (iPSCs) as well as their differentiated parental or rederived counterparts. We confirmed that only iPSCs failed to respond to viral RNA, IFN-I, or viral infection. This lack of response could be phenocopied in fibroblasts with the expression of a reprogramming factor which repressed the capacity to induce canonical antiviral pathways. To ascertain the consequences of restoring the antiviral response in the context of pluripotency, we engineered a system to engage these defenses in iPSCs. Inducible expression of a recombinant virus-activated transcription factor resulted in the successful reconstitution of antiviral defenses through the direct up-regulation of IFN-I–stimulated genes. Induction of the antiviral signature in iPSCs, even for a short duration, resulted in the dysregulation of genes associated with all three germ layers despite maintaining pluripotency markers. Trilineage differentiation of these same cells showed that engagement of the antiviral defenses compromised ectoderm and endoderm formation and dysregulated the development of mesodermal sublineages. In all, these data suggest that the temporal induction of the antiviral response primes iPSCs away from pluripotency and induces numerous aberrant gene products upon differentiation. Together these results suggest that the IFN-I system and pluripotency may be incompatible with each other and thus explain why stem cells do not utilize the canonical antiviral system.
Biosynthesis of mycobacterial methylmannose polysaccharides requires a unique 1-
O
-methyltransferase specific for 3-
O
-methylated mannosides
Authors: Ripoll-Rozada Jorge , Costa Mafalda , Manso José A. , Maranha Ana , Miranda Vanessa , Sequeira André , Ventura M. Rita , Macedo-Ribeiro Sandra , Pereira Pedro José Barbosa , Empadinhas Nuno
Published: January 2019

Mycobacteria are a wide group of organisms that includes strict pathogens, such as
Mycobacterium tuberculosis
, as well as environmental species known as nontuberculous mycobacteria (NTM), some of which—namely
Mycobacterium avium
—are important opportunistic pathogens. In addition to a distinctive cell envelope mediating critical interactions with the host immune system and largely responsible for their formidable resistance to antimicrobials, mycobacteria synthesize rare intracellular polymethylated polysaccharides implicated in the modulation of fatty acid metabolism, thus critical players in cell envelope assembly. These are the 6-
O
-methylglucose lipopolysaccharides (MGLP) ubiquitously detected across the
Mycobacterium
genus, and the 3-
O
-methylmannose polysaccharides (MMP) identified only in NTM. The polymethylated nature of these polysaccharides renders the intervening methyltransferases essential for their optimal function. Although the knowledge of MGLP biogenesis is greater than that of MMP biosynthesis, the methyltransferases of both pathways remain uncharacterized. Here, we report the identification and characterization of a unique
S
-adenosyl-
l
-methionine–dependent sugar 1-
O
-methyltransferase (MeT1) from
Mycobacterium hassiacum
that specifically blocks the 1-OH position of 3,3′-di-
O
-methyl-4α-mannobiose, a probable early precursor of MMP, which we chemically synthesized. The high-resolution 3D structure of MeT1 in complex with its exhausted cofactor,
S
-adenosyl-
l
-homocysteine, together with mutagenesis studies and molecular docking simulations, unveiled the enzyme’s reaction mechanism. The functional and structural properties of this unique sugar methyltransferase further our knowledge of MMP biosynthesis and provide important tools to dissect the role of MMP in NTM physiology and resilience.