bluuebunny/crossref_metadata_2025 huggingface dataset:
Photothermally induced accumulation and retention of polymeric nanoparticles in tumors for long-term fluorescence imaging
Authors: He Haozhe , Zheng Xiaohua , Zhang Jianxu , Liu Shi , Hu Xiuli , Xie Zhigang
Published: March 2017

Photothermal induced accumulation and retention of polymeric nanoparticles in tumor is used for long-term fluorescent imaging.
Anoxia stimulates microbially catalyzed metal release from Animas River sediments
Authors: Saup Casey M. , Williams Kenneth H. , Rodríguez-Freire Lucía , Cerrato José M. , Johnston Michael D. , Wilkins Michael J.
Published: March 2017

Experiments mimicking the burial of Animas River sediments following a mine waste spill indicate metal release linked to microbial metabolism.
A catalytic aldol condensation system enables one pot conversion of biomass saccharides to biofuel intermediates
Authors: Li Huixiang , Xu Zhanwei , Yan Peifang , Zhang Z. Conrad
Published: March 2017

In situfar infrared spectroscopy helped identify VCl3as an efficient aldol condensation catalyst which is compatible with one pot conversion of saccharides to biofuel intermediates.
Liquid sampling-atmospheric pressure glow discharge (LS-APGD) microplasmas for diverse spectrochemical analysis applications
Authors: Marcus R. Kenneth , Manard Benjamin T. , Quarles C. Derrick
Published: March 2017

The liquid sampling-atmospheric pressure glow discharge (LS-APGD) microplasma provides great diversity in sampling strategies and analytical information content.
Rapid synthesis of graphene quantum dots using a continuous hydrothermal flow synthesis approach
Authors: Kellici Suela , Acord John , Power Nicholas P. , Morgan David J. , Coppo Paolo , Heil Tobias , Saha Basudeb
Published: March 2017

A rapid and environmentally benign synthesis of green fluorescent graphene quantum dots (GQD) with low cytotoxicity via Continuous Hydrothermal Flow Synthesis (CHFS) aided by calix[4]arene tetrasulfonic acid (SCX4) as a particle size limiting agent.
Pyridinic and pyrrolic nitrogen-rich ordered mesoporous carbon for efficient oxygen reduction in microbial fuel cells
Authors: Feng Leiyu , Chen Xutao , Cao Yue , Chen Yunzhi , Wang Feng , Chen Yinguang , Liu Yin
Published: March 2017

Pyridinic and pyrrolic nitrogen-rich, ordered mesoporous carbon was used as the cathode catalyst in MFCs and showed excellent power generation capabilities.
Preparation of mechanically stable triple-layer interference broadband antireflective coatings with self-cleaning property by sol–gel technique
Authors: Li Yuanyang , Yang Ke , Xia Bibo , Yang Bowen , Yan Lianghong , He Meiying , Yan Hongwei , Jiang Bo
Published: March 2017

Mechanically stable broadband antireflective coatings with self-cleaning property were fabricatedviasol–gel method.
Morphology control and large piezoresponse of hydrothermally synthesized lead-free piezoelectric (Bi0.5Na0.5)TiO3 nanofibres
Authors: Ghasemian Mohammad Bagher , Lin Qianru , Adabifiroozjaei Esmaeil , Wang Feifei , Chu Dewei , Wang Danyang
Published: March 2017

(Bi0.5Na0.5)TiO3 nanofibers were synthesized hydrothermally, nanostructures were investigated and piezoelectric properties of single nanofibers were measured.
Effect of CdS nanocrystals on the photoluminescence of Eu3+-doped silicophosphate sol gel glass
Authors: Ben Slimen F. , Zaaboub Z. , Haouari M. , Bel Haj Mohamed N. , Ben Ouada H. , Chaussedent S. , Gaumer N.
Published: March 2017

In this work, we investigate the effect of co-doping with CdS nanoparticles on the photoluminescence properties of Eu3+ doped silicophosphate glass prepared via the sol gel method.
Structure and crystallization behavior of Al containing glasses in the CaO–B2O3–SiO2 system
Authors: Han Jiao , Lai Yuanming , Xiang Yao , Wu Shuang , Zeng Yiming , Yang Hongwei , Mao Yongyun , Yang Yuwen
Published: March 2017

The aim of the present work is to investigate the effects of Al2O3 content on both the structure and crystallization behavior of CaO–B2O3–SiO2 (CBS) glass composition using NMR, FT-IR and DSC.
Selective hydroformylation of alkyl acrylates using [2,2′-bis(dipyrrolylphosphinooxy)-1,1′-(±)-binaphthyl]/Rh catalyst: reversal of regioselectivity
Authors: Shu Xiao , Liang Haoran , Wu Qianhui , Zhou Fanding , Zheng Xueli , Fu Haiyan , Xu Bin , Li Ruixiang , Zhang Chunchun , Chen Hua
Published: March 2017

Deuterioformylation clarified the possible mechanism for the regioselectivity reversal of hydroformylation of alkyl acrylate at low and high temperature.
Improved electrical conductivity of PDMS/SCF composite sheets with bolting cloth prepared by a spatial confining forced network assembly method
Authors: Gao Xiaolong , Huang Yao , Liu Ying , Kormakov Semen , Zheng Xiuting , Wu Dan , Wu Daming
Published: March 2017

A novel method of spacial confining forced network assembly for preparation of conductive polymeric composites.
Direct exfoliation of the anode graphite of used Li-ion batteries into few-layer graphene sheets: a green and high yield route to high-quality graphene preparation
Authors: Chen Xifan , Zhu Yuanzhi , Peng Wenchao , Li Yang , Zhang GuoLiang , Zhang Fengbao , Fan Xiaobin
Published: March 2017

High-quality graphene is efficiently prepared by the direct exfoliation of the anode graphite of used Li-ion batteries.
Cyano substituted benzotriazole based polymers for use in organic solar cells
Authors: Casey Abby , Green Joshua P. , Shakya Tuladhar Pabitra , Kirkus Mindaugas , Han Yang , Anthopoulos Thomas D. , Heeney Martin
Published: March 2017

A new synthetic route to the electron accepting di-cyano substituted benzo[d][1,2,3]triazole (BTz) monomer 2-(2-butyloctyl)-4,7-di(thiophen-2-yl)-2H-benzotriazole-5,6-dicarbonitrile (dTdCNBTz) is reported.
Ultrafine transition metal dichalcogenide nanodots prepared by polyvinylpyrrolidone-assisted liquid phase exfoliation
Authors: Zhang Shan , Li Jing , Wang Erkang
Published: March 2017

Ultrafine MoSe2 nanodots were prepared by polyvinylpyrrolidone (PVP)-assisted liquid phase exfoliation, which were further applied as efficient light-absorbing agent for photothermal therapy with negligible cell toxicity and appreciable photothermal effect.
Designing an electron-transport layer for highly efficient, reliable, and solution-processed organic light-emitting diodes
Authors: Kim Jin-Hoon , Park Jin-Woo
Published: March 2017

When using PEIE doped with n-type dopants as the ETL, ϕ of the cathode decreased, significantly improving OLED performance.
Mussel-inspired polydopamine coatings for large-scale and angle-independent structural colors
Authors: Zhang Chao , Wu Bai-Heng , Du Yong , Ma Meng-Qi , Xu Zhi-Kang
Published: March 2017

This is the first time gorgeous structural colors have been presented from polydopamine-based coatingsviaa facile liquid phase deposition.
The global dust modelling framework THEMIS
Authors: Jones A. P. , Köhler M. , Ysard N. , Bocchio M. , Verstraete L.
Published: March 2017

Here we introduce the interstellar dust modelling framework THEMIS (The Heterogeneous dust Evolution Model for Interstellar Solids), which takes a global view of dust and its evolution in response to the local conditions in interstellar media. This approach is built upon a core model that was developed to explain the dust extinction and emission in the diffuse interstellar medium. The model was then further developed to self-consistently include the effects of dust evolution in the transition to denser regions. The THEMIS approach is under continuous development and we are currently extending the framework to explore the implications of dust evolution in HII regions and the photon-dominated regions associated with star formation. We provide links to the THEMIS, DustEM and DustPedia websites where more information about the model, its input data and applications can be found.
Dural Tears Associated with Burst Fractures of Lumbar Vertebrae: A Series of Three Cases
Authors: Sharma Manish , Sharma A. , Gill Maneet , Kumar Gaurav
Published: March 2017

Burst fractures of dorsolumbar vertebrae are a common occurrence. There is presence of dural tear in approximately 7.7% of cases, but its diagnosis is commonly missed because of lack of preoperative suspicion. Its preoperative diagnosis is an important adjunct in making a rationale decision for choosing surgical approaches and care during surgery. Magnetic resonance imaging (MRI) is not always helpful in its detection and has its own drawbacks. Out of a total of 27 patients operated for burst fractures of dorsolumbar vertebrae, 3 had a dural tear. Patients who were suspected to have dural tears were taken up for surgical intervention either only posteriorly or along with anterior approach. All three patients had neurologic deficits, widened interpedicular distance, laminar fracture of Gd 1 or more with canal compromise greater than 50%, and wedging with an acute angle. Presence of dural tear with wedging of roots was confirmed intraoperatively. Active effort should be made to detect presence of dural tears if patients of dorsolumbar burst fractures have neurologic deficit, laminar fracture is present, interpedicular distance is widened, and there is severe canal encroachment with an acute angle of the wedge.
First reported case of per anal endoscopic myectomy (PAEM): A novel endoscopic technique for resection of lesions with severe fibrosis in the rectum
Authors: Rahni David , Toyonaga Takashi , Ohara Yoshiko , Lombardo Francesco , Baba Shinichi , Takihara Hiroshi , Tanaka Shinwa , Kawara Fumiaki , Azuma Takeshi
Published: March 2017

Background and study aims A 54-year-old man was diagnosed with a rectal tumor extending through the submucosal layer. The patient refused surgery and therefore endoscopic submucosal dissection (ESD) was pursued. The lesion exhibited the muscle retraction sign. After dissecting circumferentially around the fibrotic area by double tunneling method, a myotomy was performed through the internal circular muscle layer, creating a plane of dissection between the internal circular muscle layer and the external longitudinal muscle layer, and a myectomy was completed.

The pathologic specimen verified T1b grade 1 sprouting adenocarcinoma with 4350 µm invasion into the submucosa with negative resection margins.
The effect of asymmetrical electrode form after negative bias illuminated stress in amorphous IGZO thin film transistors
Authors: Su Wan-Ching , Chang Ting-Chang , Liao Po-Yung , Chen Yu-Jia , Chen Bo-Wei , Hsieh Tien-Yu , Yang Chung-I , Huang Yen-Yu , Chang Hsi-Ming , Chiang Shin-Chuan , Chang Kuan-Chang , Tsai Tsung-Ming
Published: March 2017

This paper investigates the degradation behavior of InGaZnO thin film transistors (TFTs) under negative bias illumination stress (NBIS). TFT devices with two different source and drain layouts were exanimated: one having a parallel format electrode and the other with UI format electrode. UI means that source/drain electrodes shapes is defined as a forked-shaped structure. The I-V curve of the parallel electrode exhibited a symmetric degradation under forward and reverse sweeping in the saturation region after 1000 s NBIS. In contrast, the I-V curve of the UI electrode structure under similar conditions was asymmetric. The UI electrode structure also shows a stretch-out phenomenon in its C-V measurement. Finally, this work utilizes the ISE-Technology Computer Aided Design (ISE-TCAD) system simulations, which simulate the electron field and IV curves, to analyze the mechanisms dominating the parallel and UI device degradation behaviors.
Chaotic oscillator containing memcapacitor and meminductor and its dimensionality reduction analysis
Authors: Yuan Fang , Wang Guangyi , Wang Xiaowei
Published: March 2017

In this paper, smooth curve models of meminductor and memcapacitor are designed, which are generalized from a memristor. Based on these models, a new five-dimensional chaotic oscillator that contains a meminductor and memcapacitor is proposed. By dimensionality reducing, this five-dimensional system can be transformed into a three-dimensional system. The main work of this paper is to give the comparisons between the five-dimensional system and its dimensionality reduction model. To investigate dynamics behaviors of the two systems, equilibrium points and stabilities are analyzed. And the bifurcation diagrams and Lyapunov exponent spectrums are used to explore their properties. In addition, digital signal processing technologies are used to realize this chaotic oscillator, and chaotic sequences are generated by the experimental device, which can be used in encryption applications.
Space-resolved visible spectroscopy for two-dimensional measurement of hydrogen and impurity emission spectra and of plasma flow in the edge stochastic layer of LHD
Authors: Kobayashi M. , Morita S. , Goto M.
Published: March 2017

A space-resolved visible spectrometer system has been developed for two-dimensional (2D) distribution measurements of hydrogen and impurity emission spectra and of plasma flow in the edge stochastic layer of Large Helical Device (LHD). Astigmatism of the spectrometer has been suppressed by introducing additional toroidal and spherical mirrors. A good focal image at the exit slit is realized in a wide wavelength range (75 nm) as well as in a wide slit height direction (26 mm) with a 300 grooves/mm grating. The capability of the spectrometer optical system for the 2D measurement and further possible improvements are discussed in detail. An optical fiber array of 130 channels with a lens unit is used to spatially resolve the edge plasma into different magnetic field structure components: divertor strike points, divertor legs, X-point of the legs, the stochastic layer, and the last closed flux surface. With a 300 grooves/mm grating, the 2D distributions of several hydrogen and impurity line emissions are simultaneously obtained with absolute intensities. A clear correlation is obtained between the magnetic field structure and the emission intensity. With a 2400 grooves/mm grating with a good spectral resolution (0.03 nm/pixel), the 2D distributions of impurity flow velocity are obtained from the Doppler shift measurement. The wavelength position is accurately calibrated by investigating the wavelength dispersion as well as by correcting a mechanical error of the optical setting in the spectrometer. The uncertainty in the velocity is reduced to less than 10% of a typical impurity velocity ∼104 m/s. A temporal change in the flow directions is observed at different spatial locations in divertor detachment plasma.
Molecular dynamic simulations of N2-broadened methane line shapes and comparison with experiments
Authors: Le Tuong , Doménech José-Luis , Lepère Muriel , Tran Ha
Published: March 2017

Absorption spectra of methane transitions broadened by nitrogen have been calculated for the first time using classical molecular dynamic simulations. For that, the time evolution of the auto-correlation function of the dipole moment vector, assumed along a C–H axis, was computed using an accurate site-site intermolecular potential for CH4–N2. Quaternion coordinates were used to treat the rotation of the molecules. A requantization procedure was applied to the classical rotation and spectra were then derived as the Fourier-Laplace transform of the auto-correlation function. These computed spectra were compared with experimental ones recorded with a tunable diode laser and a difference-frequency laser spectrometer. Specifically, nine isolated methane lines broadened by nitrogen, belonging to various vibrational bands and having rotational quantum numbers J from 0 to 9, were measured at room temperature and at several pressures from 20 to 945 mbar. Comparisons between measured and calculated spectra were made through their fits using the Voigt profile. The results show that ab initio calculated spectra reproduce with very high fidelity non-Voigt effects on the measurements and that classical molecular dynamic simulations can be used to predict spectral shapes of isolated lines of methane perturbed by nitrogen.
On a class of quaternionic positive definite functions and their derivatives
Authors: Alpay Daniel , Colombo Fabrizio , Sabadini Irene
Published: March 2017

In this paper, we start the study of stochastic processes over the skew field of quaternions. We discuss the relation between positive definite functions and the covariance of centered Gaussian processes and the construction of stochastic processes and their derivatives. The use of perfect spaces and strong algebras and the notion of Fock space are crucial in this framework.
Penetrative convection in magnetic nanofluids via internal heating
Authors: Mahajan Amit , Sharma Mahesh Kumar
Published: March 2017

The penetrative convection induced by purely internal heating in a thin magnetic nanofluid layer is investigated within the framework of linear stability theory. The model used incorporates the effect of Brownian diffusion, thermophoresis, and magnetophoresis. The Chebyshev Pseudospectral method is employed to solve the eigenvalue problem. The results are discussed for three types of boundary conditions viz. Rigid–Rigid, Rigid–Free, and Free–Free, for water and ester based magnetic nanofluids. The effect of the important parameters on the stability of the system has been analyzed at the onset of penetrative convection.
The BepiColombo Laser Altimeter (BeLA) power converter module (PCM): Concept and characterisation
Authors: Rodrigo J. , Gasquet E. , Castro J.-M. , Herranz M. , Lara L.-M. , Muñoz M. , Simon A. , Behnke T. , Thomas N.
Published: March 2017

This paper presents the principal considerations when designing DC-DC converters for space instruments, in particular for the power converter module as part of the first European space laser altimeter: “BepiColombo Laser Altimeter” on board the European Space Agency-Japan Aerospace Exploration Agency (JAXA) mission BepiColombo. The main factors which determine the design of the DC-DC modules in space applications are printed circuit board occupation, mass, DC-DC converter efficiency, and environmental-survivability constraints. Topics included in the appropriated DC-DC converter design flow are hereby described. The topology and technology for the primary and secondary stages, input filters, transformer design, and peripheral components are discussed. Component selection and design trade-offs are described. Grounding, load and line regulation, and secondary protection circuitry (under-voltage, over-voltage, and over-current) are then introduced. Lastly, test results and characterization of the final flight design are also presented. Testing of the inrush current, the regulated output start-up, and the switching function of the power supply indicate that these performances are fully compliant with the requirements.
Surface and bulk electronic structures of heavily Mg-doped InN epilayer by hard X-ray photoelectron spectroscopy
Authors: Imura Masataka , Tsuda Shunsuke , Nagata Takahiro , Banal Ryan G. , Yoshikawa Hideki , Yang AnLi , Yamashita Yoshiyuki , Kobayashi Keisuke , Koide Yasuo , Yamaguchi Tomohiro , Kaneko Masamitsu , Uematsu Nao , Wang Ke , Araki Tsutomu , Nanishi Yasushi
Published: March 2017

To evaluate the polarity, energy band diagram, and oxygen (O) distribution of a heavily Mg-doped InN (InN:Mg+) epilayer with a Mg concentration of 1.0 ± 0.5 × 1020 cm−3, the core-level and valence band (VB) photoelectron spectra are investigated by angle-resolved soft and hard X-ray photoelectron spectroscopies. The InN:Mg+ epilayers are grown by radio-frequency plasma-assisted molecular beam epitaxy. In this doping level, the polarity inversion from In-polar to N-polar occurs with the increase in the Mg flow rate under the same growth conditions, and the VB spectrum clearly indicates the direction of polarity of InN:Mg+, which is N-polar. The energy band diagram is considered to exhibit a two-step downward bending structure due to the coexistence of the n+ surface electron accumulation layer and heavily Mg-doped p+ layer formed in the bulk. The O concentration rapidly increases until ∼4 nm with respect to the surface, which is deduced to be one of the reasons of the formation of the anomalous two-step energy band profile.
Electronic transitions of tantalum monofluoride
Authors: Ng K. F. , Zou Wenli , Liu Wenjian , Cheung A. S.-C.
Published: March 2017

The electronic transition spectrum of the tantalum monofluoride (TaF) molecule in the spectral region between 448 and 560 nm has been studied using the technique of laser-ablation/reaction free jet expansion and laser induced fluorescence spectroscopy. The TaF molecule was produced by reacting laser-ablated tantalum atoms with sulfur hexafluoride gas seeded in argon. Twenty-two vibrational bands with resolved rotational structure have been recorded and analyzed, which were organized into seven electronic transitions. The X3Σ−(0+) state has been identified to be the ground state and the determined equilibrium bond length, re, and vibrational frequency, ωe, are 1.8184 Å and 700.1 cm−1, respectively. The low-lying Λ-S states and Ω sub-states of TaF were also theoretically studied at the MRCISD+Q level of theory with spin-orbit coupling. The Ω = 0+ and 2 sub-states from the Σ−3 and Φ3 state have been found to be the ground and the first excited states, respectively, which agrees well with our experimental determinations. This work represents the first experimental investigation of the molecular structure of the TaF molecule.
A nanowire based triboelectric nanogenerator for harvesting water wave energy and its applications
Authors: Li Xiaoyi , Tao Juan , Zhu Jing , Pan Caofeng
Published: March 2017

The ocean wave energy is one of the most promising renewable and clean energy sources for human life, which is the so-called “Blue energy.” In this work, a nanowire based triboelectric nanogenerator was designed for harvesting wave energy. The nanowires on the surface of FEP largely raise the contacting area with water and also make the polymer film hydrophobic. The output can reach 10 μA and 200 V. When combined with a capacitor, an infrared emitter, and a receiver, a self-powered wireless infrared system is fabricated, which can be used in the fields of communication and detecting.
Reinventing solid state electronics: Harnessing quantum confinement in bismuth thin films
Authors: Gity Farzan , Ansari Lida , Lanius Martin , Schüffelgen Peter , Mussler Gregor , Grützmacher Detlev , Greer J. C.
Published: March 2017

Solid state electronics relies on the intentional introduction of impurity atoms or dopants into a semiconductor crystal and/or the formation of junctions between different materials (heterojunctions) to create rectifiers, potential barriers, and conducting pathways. With these building blocks, switching and amplification of electrical currents and voltages are achieved. As miniaturisation continues to ultra-scaled transistors with critical dimensions on the order of ten atomic lengths, the concept of doping to form junctions fails and forming heterojunctions becomes extremely difficult. Here, it is shown that it is not needed to introduce dopant atoms nor is a heterojunction required to achieve the fundamental electronic function of current rectification. Ideal diode behavior or rectification is achieved solely by manipulation of quantum confinement using approximately 2 nm thick films consisting of a single atomic element, the semimetal bismuth. Crucially for nanoelectronics, this approach enables room temperature operation.
Gaussian and non-Gaussian fluctuations in pure classical fluids
Authors: Naleem Nawavi , Ploetz Elizabeth A. , Smith Paul E.
Published: March 2017

The particle number, energy, and volume probability distributions in the canonical, isothermal-isobaric, grand canonical, and isobaric-isenthalpic ensembles are investigated. In particular, we consider Gaussian and non-Gaussian behavior and formulate the results in terms of a single expression valid for all the ensembles employing common, experimentally accessible, thermodynamic derivatives. This is achieved using Fluctuation Solution Theory to help manipulate derivatives of the entropy. The properties of the distributions are then investigated using available equations of state for fluid water and argon. Purely Gaussian behavior is not observed for any of the state points considered here. A set of simple measures, involving thermodynamic derivatives, indicating non-Gaussian behavior is proposed. A general expression, valid in the high temperature limit, for small energy fluctuations in the canonical ensemble is provided.
Note: Nanomechanical characterization of soft materials using a micro-machined nanoforce transducer with an FIB-made pyramidal tip
Authors: Li Z. , Gao S. , Brand U. , Hiller K. , Wollschläger N. , Pohlenz F.
Published: March 2017

The quantitative nanomechanical characterization of soft materials using the nanoindentation tech-nique requires further improvements in the performances of instruments, including their force resolution in particular. A micro-machined silicon nanoforce transducer based upon electrostatic comb drives featuring the force and depth resolutions down to ∼1 nN and 0.2 nm, respectively, is described. At the end of the MEMS transducer’s main shaft, a pyramidal tip is fabricated using a focused ion beam facility. A proof-of-principle setup with this MEMS nanoindenter has been established to measure the mechanical properties of soft polydimethylsiloxane. First measurement results demonstrate that the prototype measurement system is able to quantitatively characterize soft materials with elastic moduli down to a few MPa.
Solid-state pulse forming module with adjustable pulse duration
Authors: Wang Langning , Liu Jinliang , Qiu Yongfeng , Chu Xu , Zhang Qingmeng
Published: March 2017

A new solid-state pulse forming module is described in this paper. The pulse forming module is fabricated on a glass ceramic substrate, with the dimension of 250 mm × 95 mm × 4 mm. By changing the copper strips used in the pulse forming modules, the pulse duration of the obtained pulsed can range from 80 ns to 140 ns. Both the simulation and tests show that the pulse forming module has a good pulse forming ability. Under a high voltage in microsecond’s time, the new pulse forming modules can hold off a voltage up to 25 kV higher than that of the previous study. In addition, future optimization for the field enhancement near the thin electrode edge has been proposed and simulated.
Note: Low phase noise programmable phase-locked loop with high temperature stability
Authors: Michálek Vojtěch , Procházka Ivan
Published: March 2017

The design and construction of low jitter programmable phase-locked loop with low temperature coefficient of phase are presented. It has been designed for demanding high precision timing applications, especially as a clock source for event timer with subpicosecond precision. The phase-locked loop itself has a jitter of few hundreds of femtoseconds. It produces square wave with programmable output frequency from 100 MHz to 500 MHz and programmable amplitude of 0.25 V to 1.2 V peak-to-peak, which is locked to 5 MHz or 10 MHz reference frequency common for disciplined oscillators and highly stable clocks such as hydrogen maser. Moreover, it comprises an on-board temperature compensated crystal oscillator for stand-alone usage. The device provides temperature coefficient of the phase lock of 0.9 ps/K near room temperature.
A novel diamond anvil cell for x-ray diffraction at cryogenic temperatures manufactured by 3D printing
Authors: Jin H. , Woodall C. H. , Wang X. , Parsons S. , Kamenev K. V.
Published: March 2017

A new miniature high-pressure diamond anvil cell was designed and constructed using 3D micro laser sintering technology. This is the first application of the use of rapid prototyping technology to construct high-pressure apparatus. The cell is specifically designed for use as an X-ray diffraction cell that can be used with commercially available diffractometers and open-flow cryogenic equipment to collect data at low temperature and high pressure. The cell is constructed from stainless steel 316L and is about 9 mm in diameter and 7 mm in height, giving it both small dimensions and low thermal mass, and it will fit into the cooling envelope of a standard CryostreamTM cooling system. The cell is clamped using a customized miniature buttress thread of diameter 7 mm and pitch of 0.5 mm enabled by 3D micro laser sintering technology; such dimensions are not attainable using conventional machining. The buttress thread was used as it has favourable uniaxial load properties allowing for higher pressure and better anvil alignment. The clamp can support the load of at least 1.5 kN according to finite element analysis (FEA) simulations. FEA simulations were also used to compare the performance of the standard thread and the buttress thread, and demonstrate that stress is distributed more uniformly in the latter. Rapid prototyping of the pressure cell by the laser sintering resulted in a substantially higher tensile yield strength of the 316L stainless steel (675 MPa compared to 220 MPa for the wrought type of the same material), which increased the upper pressure limit of the cell. The cell is capable of reaching pressures of up to 15 GPa with 600 μm diameter culets of diamond anvils. Sample temperature and pressure changes on cooling were assessed using X-ray diffraction on samples of NaCl and HMT-d12.
Density functional description of size-dependent effects at nucleation on neutral and charged nanoparticles
Authors: Shchekin Alexander K. , Lebedeva Tatiana S.
Published: March 2017

A numerical study of size-dependent effects in the thermodynamics of a small droplet formed around a solid nanoparticle has been performed within the square-gradient density functional theory. The Lennard-Jones fluid with the Carnahan-Starling model for the hard-sphere contribution to intermolecular interaction in liquid and vapor phases and interfaces has been used for description of the condensate. The intermolecular forces between the solid core and condensate molecules have been taken into account with the help of the Lennard-Jones part of the total molecular potential of the core. The influence of the electric charge of the particle has been considered under assumption of the central Coulomb potential in the medium with dielectric permittivity depending on local condensate density. The condensate density profiles and equimolecular radii for equilibrium droplets at different values of the condensate chemical potential have been computed in the cases of an uncharged solid core with the molecular potential, a charged core without molecular potential, and a core with joint action of the Coulomb and molecular potentials. The appearance of stable equilibrium droplets even in the absence of the electric charge has been commented. As a next step, the capillary, disjoining pressure, and electrostatic contributions to the condensate chemical potential have been considered and compared with the predictions of classical thermodynamics in a wide range of values of the droplet and the particle equimolecular radii. With the help of the found dependence of the condensate chemical potential in droplet on the droplet size, the activation barrier for nucleation on uncharged and charged particles has been computed as a function of the vapor supersaturation. Finally, the work of droplet formation and the work of wetting the particle have been found as functions of the droplet size.
Stimulated directional emission induced by two-photon excitation of the Xe 6p′ and Xe 7p states
Authors: Alekseev V. A. , van der Burgt P. J. M. , Setser D. W.
Published: March 2017

Stimulated emission (SE) induced by pulsed two-photon excitation of the 6p′[1/2]0, 6p′[3/2]2, 7p[1/2]0, 7p[3/2]2, and 7p[5/2]2 states of the Xe atom has been studied. Spectra of SE were recorded in the 800–3500 nm region, which covers the 6p′, 7p → 7s (2500–3500 nm), 6p′, 7p → 5d (1000–2000 nm), 7s → 6p (1200–1900 nm) transitions, as well as the near-IR 6p → 6s (800–1000 nm) transitions. It is shown that excitation of the 7p states results in radiative cascade via the 7s states, 7p → 7s → 6p, although at least one case of cascading via the 5d states is also observed. Spectra of SE induced by excitation of the 6p′ states are dominated by the 6p′ → 6s′ transitions in the near IR and the 6p′ → 5d[1/2]1 → 6p[1/2]1 → 6s[3/2]1 cascade; the 6p′ → 7s → 6p cascade is also observed, although the secondary 7s → 6p emission is rather weak in comparison with excitation of the 7p states.
Predictive current control of DSTATCOM for VAR compensation of grid connected wind farms
Authors: Kandadai Venkatraman , Parvathy Selvan Manickavasagam , Sridharan Moorthi , Pitchaimuthu Raja , Kurup Deepa
Published: March 2017

This paper proposes a predictive current control scheme for an improved topology of a distribution static compensator intended for dynamic reactive power compensation of grid connected squirrel cage induction generator based wind farms. The proposed strategy derives the converter switching pulses in each sampling period using a cost function that defines the desired system behavior. Predictive current control algorithm based reactive power compensation tracks the reference current effectively and maintains unity power factor at the point of common coupling under steady state and transient conditions. Further, under transient conditions the proposed scheme provides faster and smoother reactive power compensation compared to the hysteresis controller. In addition, this scheme does not require any modulation technique. Both simulation and experimentation have been carried out to verify and validate the performance of the proposed scheme, and the results are reported in this paper.
Noise-constrained switching times for heteroclinic computing
Authors: Neves Fabio Schittler , Voit Maximilian , Timme Marc
Published: March 2017

Heteroclinic computing offers a novel paradigm for universal computation by collective system dynamics. In such a paradigm, input signals are encoded as complex periodic orbits approaching specific sequences of saddle states. Without inputs, the relevant states together with the heteroclinic connections between them form a network of states—the heteroclinic network. Systems of pulse-coupled oscillators or spiking neurons naturally exhibit such heteroclinic networks of saddles, thereby providing a substrate for general analog computations. Several challenges need to be resolved before it becomes possible to effectively realize heteroclinic computing in hardware. The time scales on which computations are performed crucially depend on the switching times between saddles, which in turn are jointly controlled by the system's intrinsic dynamics and the level of external and measurement noise. The nonlinear dynamics of pulse-coupled systems often strongly deviate from that of time-continuously coupled (e.g., phase-coupled) systems. The factors impacting switching times in pulse-coupled systems are still not well understood. Here we systematically investigate switching times in dependence of the levels of noise and intrinsic dissipation in the system. We specifically reveal how local responses to pulses coact with external noise. Our findings confirm that, like in time-continuous phase-coupled systems, piecewise-continuous pulse-coupled systems exhibit switching times that transiently increase exponentially with the number of switches up to some order of magnitude set by the noise level. Complementarily, we show that switching times may constitute a good predictor for the computation reliability, indicating how often an input signal must be reiterated. By characterizing switching times between two saddles in conjunction with the reliability of a computation, our results provide a first step beyond the coding of input signal identities toward a complementary coding for the intensity of those signals. The results offer insights on how future heteroclinic computing systems may operate under natural, and thus noisy, conditions.
Mask-free construction of three-dimensional silicon structures by dry etching assisted gray-scale femtosecond laser direct writing
Authors: Liu Xue-Qing , Yu Lei , Chen Qi-Dai , Sun Hong-Bo
Published: March 2017

A mask-free micro/nano fabrication method is proposed for constructing arbitrary gradient height structures on silicon, combining gray-scale femtosecond laser direct writing (GS-FsLDW) with subsequent dry etching. Arbitrary two-dimensional patterns with a gradient concentration of oxygen atoms can be fabricated on the surface of undoped silicon wafer by FsLDW in air. After dry etching, various three-dimensional (3D) gradient height silicon structures are fabricated by controlling the laser power, scanning step, etching time, and etching power. As an example, a well-defined 3D Fresnel zone plate was fabricated on silicon wafer, which shows excellent focusing and imaging properties. The combination of high precision from dry etching and 3D fabrication ability on non-planar substrates of FsLDW, may broaden its applications in microelectronics, micro-optics, and microelectromechanical systems.
Anisotropic charge transport properties in boron sub phthalocyanine chloride thin films
Authors: Kalia Sameer , Mahajan Aman , Ghansyam C. G. , Debnath A. K. , Saxsena Vibha , Aswal D. K. , Bedi R. K.
Published: March 2017

Anisotropic charge transport properties in organic semiconducting thin films of Boron Sub Phthalocyanine Chloride (Sub-Pc) have been studied by admittance spectroscopy applying a bias voltage parallel and perpendicular to the substrate. Sub-Pc long ordered structures confined in different directions induce anisotropic carrier mobility in films. The film with a thickness of 11 nm exhibited carrier mobilities three orders higher along the substrate than perpendicular to it. Furthermore, AFM, Kelvin Probe, and UV-Vis spectroscopic studies corroborated the established mobility-structure relationship.
Effects of Dy sub lattice dilution on transport and magnetic properties in Dy1-xKxMnO3
Authors: Yadagiri K. , Nithya R. , Shukla Neeraj , Satya A. T.
Published: March 2017

Interaction of multiple oxidation states of manganese ions with rare earth ions in manganites leads to the observation of various magnetic ground states. To understand the effect of average ionic size on electrical conductivity and magnetic ground state properties in Dy1-xKxMnO3 (x=0.0, 0.1, 0.2 & 0.3), we have investigated electron transport as a function of temperature and magnetic properties as a function of temperature, frequency and magnetic field of these compounds. Although mixed valent manganese ions can facilitate a double exchange interaction via oxygen ion leading to a ferromagnetic metallic ground state, no insulator-metal transition was detected. On the other hand, in the compounds with x=0.0 to 0.2, transport properties suggested an adiabatic small polaron hopping conduction mechanism. However, x=0.3 compound followed a variable range hopping conduction. Temperature variation of magnetization data exhibited three different types of transitions involving Mn and Dy ions. The bifurcation between zero field cooled and field cooled magnetization data was observed in all the compounds. Field-dependent magnetization of all the compounds showed hysteresis loops for temperatures less than 10 K. Although large irreversibility between zero field cooled and field cooled magnetization data was observed with a peak for x=0.3, the peak temperatures did not alter with frequency ruling out the possibility of spin glass behavior. The presence of hysteresis loops and lack of saturation magnetization implied the simultaneous presence of ferromagnetic and antiferromagnetic exchange interactions well within the antiferromagnetic ordering of Mn ions.
SiNx coatings deposited by reactive high power impulse magnetron sputtering: Process parameters influencing the residual coating stress
Authors: Schmidt S. , Hänninen T. , Wissting J. , Hultman L. , Goebbels N. , Santana A. , Tobler M. , Högberg H.
Published: March 2017

The residual coating stress and its control is of key importance for the performance and reliability of silicon nitride (SiNx) coatings for biomedical applications. This study explores the most important deposition process parameters to tailor the residual coating stress and hence improve the adhesion of SiNx coatings deposited by reactive high power impulse magnetron sputtering (rHiPIMS). Reactive sputter deposition and plasma characterization were conducted in an industrial deposition chamber equipped with pure Si targets in N2/Ar ambient. Reactive HiPIMS processes using N2-to-Ar flow ratios of 0 and 0.28–0.3 were studied with time averaged positive ion mass spectrometry. The coatings were deposited to thicknesses of 2 μm on Si(001) and to 5 μm on polished CoCrMo disks. The residual stress of the X-ray amorphous coatings was determined from the curvature of the Si substrates as obtained by X-ray diffraction. The coatings were further characterized by X-ray photoelectron spectroscopy, scanning electron microscopy, and nanoindentation in order to study their elemental composition, morphology, and hardness, respectively. The adhesion of the 5 μm thick coatings deposited on CoCrMo disks was assessed using the Rockwell C test. The deposition of SiNx coatings by rHiPIMS using N2-to-Ar flow ratios of 0.28 yield dense and hard SiNx coatings with Si/N ratios <1. The compressive residual stress of up to 2.1 GPa can be reduced to 0.2 GPa using a comparatively high deposition pressure of 600 mPa, substrate temperatures below 200 °C, low pulse energies of <2.5 Ws, and moderate negative bias voltages of up to 100 V. These process parameters resulted in excellent coating adhesion (ISO 0, HF1) and a low surface roughness of 14 nm for coatings deposited on CoCrMo.
Angular dependence of plasma parameters and film properties during high power impulse magnetron sputtering for deposition of Ti and TiO2 layers
Authors: Hippler R. , Hubicka Z. , Cada M. , Ksirova P. , Wulff H. , Helm C. A. , Stranak V.
Published: March 2017

Angular distribution measurements have been carried out during High Power Impulse Magnetron Sputtering (HiPIMS) of a titanium target and deposition of titanium and titanium oxide films. The HiPIMS system was operated at a repetition frequency f = 100 Hz with a duty cycle of 1%. Langmuir probe diagnostics has been carried out at a distance of 7.5 cm from the target at four different angles with respect to the surface normal of the target. Film properties were investigated by means of SEM, XR, and GIXD, and a dependence of film thickness and crystalline structure on the deposition angle is observed.
Temperature-dependent optical properties of titanium nitride
Authors: Briggs Justin A. , Naik Gururaj V. , Zhao Yang , Petach Trevor A. , Sahasrabuddhe Kunal , Goldhaber-Gordon David , Melosh Nicholas A. , Dionne Jennifer A.
Published: March 2017

The refractory metal titanium nitride is promising for high-temperature nanophotonic and plasmonic applications, but its optical properties have not been studied at temperatures exceeding 400 °C. Here, we perform in-situ high-temperature ellipsometry to quantify the permittivity of TiN films from room temperature to 1258 °C. We find that the material becomes more absorptive at higher temperatures but maintains its metallic character throughout visible and near infrared frequencies. X-ray diffraction, atomic force microscopy, and mass spectrometry confirm that TiN retains its bulk crystal quality and that thermal cycling increases the surface roughness, reduces the lattice constant, and reduces the carbon and oxygen contaminant concentrations. The changes in the optical properties of the material are highly reproducible upon repeated heating and cooling, and the room-temperature properties are fully recoverable after cooling. Using the measured high-temperature permittivity, we compute the emissivity, surface plasmon polariton propagation length, and two localized surface plasmon resonance figures of merit as functions of temperature. Our results indicate that titanium nitride is a viable plasmonic material throughout the full temperature range explored.
Emission enhancement of underwater collinear dual-pulse laser-induced breakdown spectroscopy with the second pulse defocused
Authors: Xue Boyang , Li Nan , Lu Yuan , Li Yuandong , Zheng Ronger
Published: March 2017

Axial focusing arrangement effects on collinear dual-pulse laser-induced breakdown spectroscopy (DP-LIBS) in a bulk solution were investigated by spectra and fast images. By properly defocusing the second laser pulse beyond the first laser formed bubble (LFB), brighter and larger plasmas could be produced due to higher breakdown efficiency and higher expansion efficiency. It is attributed to a distinct mechanism of underwater DP-LIBS that the plasma mostly forms at the bubble-water interface and then expands into the gaseous LFB. The results show that optimization of the axial focusing arrangement in underwater collinear DP-LIBS enables significant emission enhancements with relatively low laser energies.
GaN surface states investigated by electrochemical studies
Authors: Winnerl Andrea , Garrido Jose A. , Stutzmann Martin
Published: March 2017

We present a systematic study of electrochemically active surface states on MOCVD-grown n-type GaN in aqueous electrolytes using cyclic voltammetry and impedance spectroscopy over a wide range of potentials and frequencies. In order to alter the surface states, the GaN samples are either etched or oxidized, and the influence of the surface treatment on the defect-mediated charge transfer to the electrolyte is investigated. Etching in HCl removes substoichiometric GaOx, and leads to a pronounced density of electrochemically active surface states. Oxidation effectively removes these surface states.
The role of nitrogen doping in ALD Ta2O5 and its influence on multilevel cell switching in RRAM
Authors: Sedghi N. , Li H. , Brunell I. F. , Dawson K. , Potter R. J. , Guo Y. , Gibbon J. T. , Dhanak V. R. , Zhang W. D. , Zhang J. F. , Robertson J. , Hall S. , Chalker P. R.
Published: March 2017

The role of nitrogen doping on the stability and memory window of resistive state switching in N-doped Ta2O5 deposited by atomic layer deposition is elucidated. Nitrogen incorporation increases the stability of resistive memory states which is attributed to neutralization of electronic defect levels associated with oxygen vacancies. The density functional simulations with the screened exchange hybrid functional approximation show that the incorporation of nitrogen dopant atoms in the oxide network removes the O vacancy midgap defect states, thus nullifying excess defects and eliminating alternative conductive paths. By effectively reducing the density of vacancy-induced defect states through N doping, 3-bit multilevel cell switching is demonstrated, consisting of eight distinctive resistive memory states achieved by either controlling the set current compliance or the maximum voltage during reset. Nitrogen doping has a threefold effect: widening the switching memory window to accommodate the more intermediate states, improving the stability of states, and providing a gradual reset for multi-level cell switching during reset. The N-doped Ta2O5 devices have relatively small set and reset voltages (< 1 V) with reduced variability due to doping.
X-ray-induced acoustic computed tomography with an ultrasound transducer ring-array
Authors: Tang S. , Nguyen D. H. , Zarafshani A. , Ramseyer C. , Zheng B. , Liu H. , Xiang L.
Published: March 2017

The objective of this study is to develop and test a unique X-ray-induced acoustic computed tomography system that combines the advantages of high X-ray imaging contrast and high ultrasonic spatial resolution. The system features a 5 MHz 128-element ultrasound transducer ring-array formed into a full circular aperture. A parallel data receiver, which consists of a dedicated 128-channel preamplifier and a 128-channel data acquisition module, provides full tomographic imaging at a speed of up to 25 frames per second. Details of the system design and calibration are presented, along with the characteristic results of the imaging resolution. The tomographic imaging performance is demonstrated through images of a phantom with a spatial resolution up to 138 μm. The study results indicate that this imaging device and the methodology provide a rapid and high resolution approach for the dynamic imaging of information, and it may have the potential for becoming a promising noninvasive imaging modality to be used in future applications.