bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of Severe Arterial Phase Respiratory Motion Artifact on Gadoxetate Disodium-Enhanced MRI – Assessment of Interrater Agreement and Reliability
Authors: Ringe Kristina , Luetkens Julian , Fimmers Rolf , Hammerstingl Renate , Layer Günter , Maurer Martin , Nähle Claas Philip , Michalik Sabine , Reimer Peter , Schraml Christina , Schreyer Andreas , Stumpp Patrick , Vogl Thomas , Wacker Frank , Willinek Winfried , Kukuk Guido
Published: February 2018

Purpose To assess the interrater agreement and reliability of experienced abdominal radiologists in the characterization and grading of arterial phase gadoxetate disodium-related respiratory motion artifact on liver MRI.

Materials and Methods This prospective multicenter study was initiated by the working group for abdominal imaging within the German Roentgen Society (DRG), and approved by the local IRB of each participating center. 11 board-certified radiologists independently reviewed 40 gadoxetate disodium-enhanced liver MRI datasets. Motion artifacts in the arterial phase were assessed on a 5-point scale. Interrater agreement and reliability were calculated using the intraclass correlation coefficient (ICC) and Kendall coefficient of concordance (W), with p < 0.05 deemed significant.

Results The ICC for interrater agreement and reliability were 0.983 (CI 0.973 – 0.990) and 0.985 (CI 0.978 – 0.991), respectively (both p < 0.0001), indicating excellent agreement and reliability. Kendall’s W for interrater agreement was 0.865. A severe motion artifact, defined as a mean motion score ≥ 4 in the arterial phase was observed in 12 patients. In these specific cases, a motion score ≥ 4 was assigned by all readers in 75 % (n = 9/12 cases).

Conclusion Differentiation and grading of arterial phase respiratory motion artifact is possible with a high level of inter-/intrarater agreement and interrater reliability, which is crucial for assessing the incidence of this phenomenon in larger multicenter studies.

Key Points 

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Lessons from pathological analysis of recurrent early esophageal squamous cell neoplasia after complete endoscopic radiofrequency ablation
Authors: Wang Wen-Lun , Chang I-Wei , Chen Chien-Chuan , Chang Chi-Yang , Tseng Cheng-Hao , Tai Chi-Ming , Lin Jaw-Town , Wang Hsiu-Po , Lee Ching-Tai
Published: February 2018

Background Endoscopic radiofrequency ablation (RFA) is a treatment option for early esophageal squamous cell neoplasia (ESCN); however, long-term follow-up studies are lacking. The risks of local recurrence and “buried cancer” are also uncertain.

Methods Patients with flat-type ESCN who were treated with balloon-type ± focal-type RFA were consecutively enrolled. Follow-up endoscopy was performed at 1, 3, and 6 months, and then every 6 months thereafter. Endoscopic resection was performed for persistent and recurrent ESCN, and the histopathology of resected specimens was assessed.

Results A total of 35 patients were treated with RFA, of whom 30 (86 %) achieved a complete response, three were lost to follow-up, and five (14 %) developed post-RFA stenosis. Two patients had persistent ESCN and received further endoscopic resection, in which the resected specimens all revealed superficial submucosal invasive cancer. Six of the 30 patients with successful RFA (20 %) developed a total of seven episodes of local recurrence (mean size 1.4 cm) during the follow-up period (mean 40.1 months), all of which were successfully resected endoscopically without adverse events. Histological analysis of the resected specimens revealed that six (86 %) had esophageal glandular ductal involvement, all of which extended deeper than the muscularis mucosae layer. Immunohistochemistry staining for P53 and Ki67 suggested a clonal relationship between the ductal involvement and epithelial cells. None of the tumors extended out of the ductal structure; no cases of cancer buried beneath the normal neosquamous epithelium were found.

Conclusions Because ductal involvement is not uncommon and may be related to recurrence, the use of RFA should be conservative and may not be the preferred primary treatment for early ESCN.
Analysis of a Bianchi-like equation satisfied by the Mars-Simon tensor
Authors: Beyer Florian , Paetz Tim-Torben
Published: February 2018

The Mars-Simon tensor (MST), which, e.g., plays a crucial role to provide gauge invariant characterizations of the Kerr-NUT-(A)(dS) family, satisfies a Bianchi-like equation. In this paper, we analyze this equation in close analogy to the Bianchi equation, in particular it will be shown that the constraints are preserved supposing that a generalized Buchdahl condition holds. This permits the systematic construction of solutions to this equation in terms of a well-posed Cauchy problem. A particular emphasis lies on the asymptotic Cauchy problem, where data are prescribed on a space-like I (i.e., for ∧ > 0). In contrast to the Bianchi equation, the MST equation is of Fuchsian type at I, for which existence and uniqueness results are derived.
Molecular dynamics simulation of ion mobility in gases
Authors: Lai Rui , Dodds Eric D. , Li Hui
Published: February 2018

A force field molecular dynamics method is developed to directly simulate ion drift in buffer gases driven by an electric field. The ion mobility and collision cross sections (CCSs) with relevance to ion mobility spectrometry can be obtained from the simulated drift velocity in high-density buffer gases (pressure ∼50 bars) and high electric fields (∼107 V/m). Compared to trajectory methods, the advantage of the molecular dynamics method is that it can simultaneously sample the internal dynamic motions of the ion and the ion-gas collisions. For ions with less than 100 atoms, the simulated collision cross section values can be converged to within ±1%–2% by running a 100 ns simulation for 5–19 h using one computer core. By using a set of element-based Lennard-Jones parameters that are not tuned for different atomic types in different molecules, the simulated collision cross sections for 15 small molecular ions (number of atoms ranging from 17 to 85, mass ranging from 74.1 to 609.4 g/mol) are consistent with experimental values: the mean unsigned error is 2.6 Å2 for He buffer gas and 4.4 Å2 for N2 buffer gas. The sensitivity of the simulated CCS values to random diffusion, drift velocity, electric field strength, temperature, and buffer gas density is examined.
Indium antimonide detector for spectral characterization of terahertz sources
Authors: Yavorskiy D. , Karpierz K. , Grynberg M. , Knap W. , Łusakowski J.
Published: February 2018

The goal of this study was to establish conditions under which a magnetic-field-tunable InSb detector can be used to characterize the radiation spectrum of terahertz (THz) sources. The response of a bulk InSb detector to a monochromatic radiation with the frequency 0.1 < f < 4.6 THz was studied at liquid helium temperatures and magnetic fields B up to 5 T. A constant voltage (measurements of photocurrent) or a constant current (measurements of photoresistance) biasing condition was tested, and both signals were found to be strongly influenced by magnetoresistance of the detector. At f≲0.5 THz, a photoresponse was observed in the whole range of B, which reflected a non-resonant absorption by free electrons and had no relation to cyclotron-resonance-related transitions. Resonant transitions developed gradually at f≳0.5 THz and dominated the spectra only at f≳1.0 THz. Thus, we show that only at this latter frequency range, the detector can be used for a spectral characterization of unknown sources. To avoid false interpretation of measured signals, a detector should be supplied with a 1-THz high-pass filter.
Analysis on the effects of China's fiscal and taxation policy on exporting products of photovoltaic and high-end equipment manufacturing industries
Authors: Xiong Yongqing , Yang Xiaohan , Song Mengjie
Published: February 2018

China's fiscal and taxation subsidy policy plays a positive role in promoting the international market development of emerging industries, which also brought about many problems. In this paper, countries with large overseas investment from China and those along the “One Belt One Road” project were specially selected and divided into different types of international markets according to parameters of political risk, relations with China, geographical locations, etc. The computable general equilibrium model was then used to analyze the change in the export volume to different types of countries influenced by the change in export tax rebate ratios and research and development (R&D) subsidies. Simulation results showed that the change in export tax rebate policy has a greater impact on the photovoltaic industry and a relatively low impact on the high-end equipment manufacturing industry. The change in the export tax rebate rate has different effects on the export volume of countries in different regions and has the greatest effect on the high risk region and the partnership region. Additionally, R&D subsidy has different effects on the export volume of countries in different regions and has the greatest effect on the low risk region and the poorer relation region. Therefore, suitable subsidy policy should be decided, based on the characteristics of foreign markets in different regions. Contributions of this study are expected to be used in governmental policy designing and company development strategy optimization.
Characterization of a new Hencken burner with a transition from a reducing-to-oxidizing environment for fundamental coal studies
Authors: Adeosun Adewale , Huang Qian , Li Tianxiang , Gopan Akshay , Wang Xuebin , Li Shuiqing , Axelbaum Richard L.
Published: February 2018

In pulverized coal burners, coal particles usually transition from a locally reducing environment to an oxidizing environment. The locally reducing environment in the near-burner region is due to a dense region of coal particles undergoing devolatilization. Following this region, the particles move into an oxidizing environment. This “reducing-to-oxidizing” transition can influence combustion processes such as ignition, particulate formation, and char burnout. To understand these processes at a fundamental level, a system is required that mimics such a transition. Hence, we have developed and characterized a two-stage Hencken burner to evaluate the effect of the reducing-to-oxidizing transition and particle-to-particle interaction (which characterizes dense region of coal particles) on ignition and ultrafine aerosol formation. The two-stage Hencken burner allows coal particles to experience a reducing environment followed by a transition to an oxidizing environment. This work presents the results of the design and characterization of the new two-stage Hencken burner and its new coal feeder. In a unique approach to the operation of the flat-flame of the Hencken burner, the flame configurations are operated as either a normal flame or inverse flame. Gas temperatures and oxygen concentrations for the Hencken burner are measured in reducing-to-oxidizing and oxidizing environments. The results show that stable flames with well-controlled conditions, relatively uniform temperatures, and species concentrations can be achieved in both flame configurations. This new Hencken burner provides an effective system for evaluating the effect of the reducing-to-oxidizing transition and particle-to-particle interaction on early-stage processes of coal combustion such as ignition and ultrafine particle formation.
Error analysis of mechanical system and wavelength calibration of monochromator
Authors: Zhang Fudong , Chen Chen , Liu Jie , Wang Zhihong
Published: February 2018

This study focuses on improving the accuracy of a grating monochromator on the basis of the grating diffraction equation in combination with an analysis of the mechanical transmission relationship between the grating, the sine bar, and the screw of the scanning mechanism. First, the relationship between the mechanical error in the monochromator with the sine drive and the wavelength error is analyzed. Second, a mathematical model of the wavelength error and mechanical error is developed, and an accurate wavelength calibration method based on the sine bar’s length adjustment and error compensation is proposed. Based on the mathematical model and calibration method, experiments using a standard light source with known spectral lines and a pre-adjusted sine bar length are conducted. The model parameter equations are solved, and subsequent parameter optimization simulations are performed to determine the optimal length ratio. Lastly, the length of the sine bar is adjusted. The experimental results indicate that the wavelength accuracy is ±0.3 nm, which is better than the original accuracy of ±2.6 nm. The results confirm the validity of the error analysis of the mechanical system of the monochromator as well as the validity of the calibration method.
Thermal characterization of gallium nitride p-i-n diodes
Authors: Dallas J. , Pavlidis G. , Chatterjee B. , Lundh J. S. , Ji M. , Kim J. , Kao T. , Detchprohm T. , Dupuis R. D. , Shen S. , Graham S. , Choi S.
Published: February 2018

In this study, various thermal characterization techniques and multi-physics modeling were applied to understand the thermal characteristics of GaN vertical and quasi-vertical power diodes. Optical thermography techniques typically used for lateral GaN device temperature assessment including infrared thermography, thermoreflectance thermal imaging, and Raman thermometry were applied to GaN p-i-n diodes to determine if each technique is capable of providing insight into the thermal characteristics of vertical devices. Of these techniques, thermoreflectance thermal imaging and nanoparticle assisted Raman thermometry proved to yield accurate results and are the preferred methods of thermal characterization of vertical GaN diodes. Along with this, steady state and transient thermoreflectance measurements were performed on vertical and quasi-vertical GaN p-i-n diodes employing GaN and Sapphire substrates, respectively. Electro-thermal modeling was performed to validate measurement results and to demonstrate the effect of current crowding on the thermal response of quasi-vertical diodes. In terms of mitigating the self-heating effect, both the steady state and transient measurements demonstrated the superiority of the tested GaN-on-GaN vertical diode compared to the tested GaN-on-Sapphire quasi-vertical structure.
Evaluation of hydrogen absorption cells for observations of the planetary coronas
Authors: Kuwabara M. , Taguchi M. , Yoshioka K. , Ishida T. , de Oliveira N. , Ito K. , Kameda S. , Suzuki F. , Yoshikawa I.
Published: February 2018

Newly designed Lyman-alpha absorption cells for imaging hydrogen planetary corona were characterized using an ultra high resolution Fourier transform spectrometer installed on the DESIRS (Dichroïsme Et Spectroscopie par Interaction avec le Rayonnement Synchrotron) beamline of Synchrotron SOLEIL in France. The early absorption cell installed in the Japanese Mars orbiter NOZOMI launched in 1998 had not been sufficiently optimized due to its short development time. The new absorption cells are equipped with the ability to change various parameters, such as filament shape, applied power, H2 gas pressure, and geometrical configuration. We found that the optical thickness of the new absorption cell was ∼4 times higher than the earlier one at the center wavelength of Lyman-alpha absorption, by optimizing the condition to promote thermal dissociation of H2 molecules into two H atoms on a hot tungsten filament. The Doppler temperature of planetary coronas could be determined with an accuracy better than 100 K with the performance of the newly developed absorption cell.
Electron-acoustic solitary waves in the Earth's inner magnetosphere
Authors: Dillard C. S. , Vasko I. Y. , Mozer F. S. , Agapitov O. V. , Bonnell J. W.
Published: February 2018

The broadband electrostatic turbulence observed in the inner magnetosphere is produced by large-amplitude electrostatic solitary waves of generally two types. The solitary waves with symmetric bipolar parallel (magnetic field-aligned) electric field are electron phase space holes. The solitary waves with highly asymmetric bipolar parallel electric field have been recently shown to correspond to the electron-acoustic plasma mode (existing due to two-temperature electron population). Through theoretical and numerical analysis of hydrodynamic and modified Korteweg-de Vries equations, we demonstrate that the asymmetric solitary waves appear due to the steepening of initially quasi-monochromatic electron-acoustic perturbation arrested at some moment by collisionless dissipation (Landau damping). The typical steepening time is found to be from a few to tens of milliseconds. The steepening of the electron-acoustic waves has not been reproduced in self-consistent kinetic simulations yet, and factors controlling the formation of steepened electron-acoustic waves, rather than electron phase space holes, remain unclear.
Lattice strain induced multiferroicity in PZT-CFO particulate composite
Authors: Pradhan Lagen Kumar , Pandey Rabichandra , Kumar Rajnish , Kar Manoranjan
Published: February 2018

Lead Zirconate Titanate [Pb(Zr0.52Ti0.48)O3/PZT] and Cobalt Ferrite [CoFe2O4/CFO] based multiferroic composites [(1-x)PZT-(x)CFO] with (x = 0.10–0.40) have been prepared to study its magnetoelectric (ME) and multiferroic properties. X-ray diffraction method along with the Rietveld refinement technique reveals that the crystal symmetries corresponding to PZT and CFO exist independently in the composites. The effect of interfacial strain on lattice distortion in PZT has been observed. It is well correlated with the magnetoelectric coupling of the composites. Dispersion behavior of dielectric constant with frequency can be explained by the modified Debye model. Different relaxation phenomena have been observed in PZT-CFO particulate composites. The ferroelectric properties of composites decrease with the increase in percentage of CFO in the composite. Both saturation (Ms) and remanent (Mr) magnetization increase with the increase in CFO content in the composite. The maximum ME coupling was found to be 1.339 pC/cm2 Oe for the composition (0.80) PZT-(0.20) CFO at the application of maximum magnetic field of 50 Oe. The multiferroic properties in CFO-PZT can be explained by the lattice strain at the CFO-PZT interfaces.
Carbon nanotube-based black coatings
Authors: Lehman J. , Yung C. , Tomlin N. , Conklin D. , Stephens M.
Published: February 2018

Coatings comprising carbon nanotubes are very black, that is, characterized by uniformly low reflectance over a broad range of wavelengths from the visible to far infrared. Arguably, there is no other material that is comparable. This is attributable to the intrinsic properties of graphitic material as well as the morphology (density, thickness, disorder, and tube size). We briefly describe a history of other coatings such as nickel phosphorous, gold black, and carbon-based paints and the comparable structural morphology that we associate with very black coatings. The need for black coatings is persistent for a variety of applications ranging from baffles and traps to blackbodies and thermal detectors. Applications for space-based instruments are of interest and we present a review of space qualification and the results of outgassing measurements. Questions of nanoparticle safety depend on the nanotube size and aspect ratio as well as the nature and route of exposure. We describe the growth of carbon nanotube forests along with the catalyst requirements and temperature limitations. We also describe coatings derived from carbon nanotubes and applied like paint. Building the measurement apparatus and determining the optical properties of something having negligible reflectance are challenging and we summarize the methods and means for such measurements. There exists information in the literature for effective media approximations to model the dielectric function of vertically aligned arrays. We summarize this along with the refractive index of graphite from the literature that is necessary for modeling the optical properties. In our experience, the scientific questions can be overshadowed by practical matters, so we provide an appendix of recipes for making as-grown and sprayed coatings along with an example of reflectance measurements.
Enhancement of hot-carrier photoluminescence with intense terahertz pulses
Authors: Purschke D. N. , Na M. , Longman A. , Titova L. V. , Hegmann F. A.
Published: February 2018

Intense terahertz (THz) pulses have been shown to induce photoluminescence (PL) quenching in bulk semiconductors. We show that in addition to PL quenching near the bandgap, intense THz pulses enhance the high-energy tail of the PL in GaAs. Furthermore, we propose a simple model that accounts for both PL quenching and enhancement where THz-induced hot carriers directly enhance high-energy PL but reduce overall radiative efficiency due to ultrafast diffusion. Exploring the interplay between THz-induced PL enhancement and quenching over a range of excitation parameters reveals a reduction of integrated PL at low photoexcitation fluence, while at higher fluences, the amplitude of the PL quenching is balanced by that of the PL enhancement.
The precise and accurate production of millimetric water droplets using a superhydrophobic generating apparatus
Authors: Wood Michael J. , Aristizabal Felipe , Coady Matthew , Nielson Kent , Ragogna Paul J. , Kietzig Anne-Marie
Published: February 2018

The production of millimetric liquid droplets has importance in a wide range of applications both in the laboratory and industrially. As such, much effort has been put forth to devise methods to generate these droplets on command in a manner which results in high diameter accuracy and precision, well-defined trajectories followed by successive droplets and low oscillations in droplet shape throughout their descents. None of the currently employed methods of millimetric droplet generation described in the literature adequately addresses all of these desired droplet characteristics. The reported methods invariably involve the cohesive separation of the desired volume of liquid from the bulk supply in the same step that separates the single droplet from the solid generator. We have devised a droplet generation device which separates the desired volume of liquid within a tee-apparatus in a step prior to the generation of the droplet which has yielded both high accuracy and precision of the diameters of the final droplets produced. Further, we have engineered a generating tip with extreme antiwetting properties which has resulted in reduced adhesion forces between the liquid droplet and the solid tip. This has yielded the ability to produce droplets of low mass without necessitating different diameter generating tips or the addition of surfactants to the liquid, well-defined droplet trajectories, and low oscillations in droplet volume. The trajectories and oscillations of the droplets produced have been assessed and presented quantitatively in a manner that has been lacking in the current literature.
VO2 film temperature dynamics at low-frequency current self-oscillations
Authors: Bortnikov S. G. , Aliev V. Sh. , Badmaeva I. A. , Mzhelskiy I. V.
Published: February 2018

Low-frequency (∼2 Hz) current self-oscillations were first obtained in a millimeter-sized two-terminal planar device with a vanadium dioxide (VO2) film. The film temperature distribution dynamics was investigated within one oscillation period. It was established that the formation and disappearance of a conductive channel occur in a film in less than 60 ms with oscillation period 560 ms. The experimentally observed temperature in the channel region reached 413 K, being understated due to a low infrared microscope performance (integration time 10 ms). The VO2 film temperature distribution dynamics was simulated by solving a 2D problem of the electric current flow and heat transfer in the film. The calculation showed that the thermally initiated resistance switching in the film occurs in less than 4 ms at a channel temperature reaching ∼1000 K. The experimental results and simulation are consistent with the current self-oscillation mechanism based on the current pinching and dielectric relaxation in the VO2 film at the metal-insulator phase transition.
Defect localization of metal interconnection lines in 3-dimensional through-silicon-via structures by differential scanning photocapacitance microscopy
Authors: Jacobs K. J. P. , Stucchi M. , Afanas'ev V. V. , Gonzalez M. , Croes K. , De Wolf I. , Beyne E.
Published: February 2018

We report a differential scanning photocapacitance microscopy technique based on the detection of light-induced capacitance changes allowing mapping of metal interconnection line defects in through-silicon-via (TSV) structures used in three-dimensional (3-D) integration technology. Due to the photosensitive silicon depletion capacitance, observation of the photocapacitance response enables non-destructive two-dimensional (2-D) visualization of metallization line ruptures in TSV structures. We demonstrate the application of the proposed method on a TSV chain structure and reveal the location of the open metallization rupture.
Laser desorption vs. electrospray of polyyne-threaded rotaxanes: Preventing covalent cross-linking and promoting noncovalent aggregation
Authors: Neugebauer Thomas S. , Franz Michael , Frankenberger Stephanie , Tykwinski Rik R. , Drewello Thomas
Published: February 2018

Laser-induced cross-linking of polyynes is successfully hindered when the polyyne is encapsulated as part of a rotaxane and therefore protected by a surrounding macrocycle. When the rotaxane is electrosprayed, however, noncovalent aggregate ions are efficiently formed. Aggregates of considerable size (including more than 50 rotaxane molecules with masses beyond 100k Da) and charge states (up to 13 charges and beyond) have been observed. Either protons or sodium cations act as the charge carriers. These aggregates are not formed when the individual components of the rotaxane, i.e., the macrocycle or the polyyne, are separately electrosprayed. This underlines the structural importance of the rotaxane for the aggregate formation. Straightforward force field calculations indicate that the polyyne thread hinders the folding of the macrocycles, which facilitates the bonding interaction between the two components.
High quality factor surface Fabry-Perot cavity of acoustic waves
Authors: Xu Yuntao , Fu Wei , Zou Chang-ling , Shen Zhen , Tang Hong X.
Published: February 2018

Surface acoustic wave (SAW) resonators are critical components in wireless communications and many sensing applications. They have also recently emerged as a subject of study in quantum acoustics at the single phonon level. Acoustic loss reduction and mode confinement are key performance factors in SAW resonators. Here, we report the design and experimental realization of high quality factor Fabry-Perot SAW resonators formed in between the tapered phononic crystal mirrors patterned on a GaN-on-sapphire material platform. The fabricated SAW resonators are characterized by both an electrical network analyzer and an optical heterodyne vibrometer. We observed standing Rayleigh waves inside the cavity, with an intrinsic quality factor exceeding 1.3 × 104 at ambient conditions.
Study of velocity and temperature distributions in boundary layer flow of fourth grade fluid over an exponential stretching sheet
Authors: Khan Najeeb Alam , Saeed Umair Bin , Sultan Faqiha , Ullah Saif , Rehman Abdul
Published: February 2018

This study deals with the investigation of boundary layer flow of a fourth grade fluid and heat transfer over an exponential stretching sheet. For analyzing two heating processes, namely, (i) prescribed surface temperature (PST), and (ii) prescribed heat flux (PHF), the temperature distribution in a fluid has been considered. The suitable transformations associated with the velocity components and temperature, have been employed for reducing the nonlinear model equation to a system of ordinary differential equations. The flow and temperature fields are revealed by solving these reduced nonlinear equations through an effective analytical method. The important findings in this analysis are to observe the effects of viscoelastic, cross-viscous, third grade fluid, and fourth grade fluid parameters on the constructed analytical expression for velocity profile. Likewise, the heat transfer properties are studied for Prandtl and Eckert numbers.
On-chip III-V monolithic integration of heralded single photon sources and beamsplitters
Authors: Belhassen J. , Baboux F. , Yao Q. , Amanti M. , Favero I. , Lemaître A. , Kolthammer W. S. , Walmsley I. A. , Ducci S.
Published: February 2018

We demonstrate a monolithic III-V photonic circuit combining a heralded single photon source with a beamsplitter, at room temperature and telecom wavelength. Pulsed parametric down-conversion in an AlGaAs waveguide generates counterpropagating photons, one of which is used to herald the injection of its twin into the beamsplitter. We use this configuration to implement an integrated Hanbury-Brown and Twiss experiment, yielding a heralded second-order correlation gher(2)(0)=0.10±0.02 that confirms single-photon operation. The demonstrated generation and manipulation of quantum states on a single III-V semiconductor chip opens promising avenues towards real-world applications in quantum information.
Interplay between developing flow length and bubble departure diameter during macroconvection enhanced pool boiling
Authors: Jaikumar A. , Emery T. S. , Kandlikar S. G.
Published: February 2018

Enhanced boiling structures based on the concept of separate liquid-vapor (L-V) pathways rely on the motion of the bubbles departing from the nucleating regions (NRs) to induce a macroconvective liquid jet impingement flow over adjacent non-boiling regions. Heat transfer in the non-boiling regions can be improved by incorporating microchannels which act as feeder channels (FCs) that also improve liquid directionality towards the NR. We hypothesize that the single-phase flow characteristics in the developing region of the FC contribute to the boiling enhancement and explore the interplay between the FC length, developing flow length, and departure bubble diameter. FC lengths shorter than the developing flow length benefit from the enhancement due to developing boundary layers over their entire length. However, FC lengths shorter than the departure bubble diameter suffer from bubble interference while FC lengths that are considerably longer than the developing flow length exhibit lower heat transfer rates in the fully developed region. This hypothesis was verified by conducting pool boiling experiments with four feeder channel lengths between 1 mm and 3 mm using HFE-7000, PP1, PP1C, and water. Three distinct regions: (i) interfering bubble, (ii) efficient L-V pathways, and (iii) diminished jet were identified to explain the boiling performance enhancement. This analysis will be beneficial in the pursuit to enhance critical heat flux (CHF) and heat transfer coefficient (HTC) on surfaces utilizing macroconvection mechanisms during boiling with different liquids.
Incorporating extrinsic noise into the stochastic simulation of biochemical reactions: A comparison of approaches
Authors: Thanh Vo Hong , Marchetti Luca , Reali Federico , Priami Corrado
Published: February 2018

The stochastic simulation algorithm (SSA) has been widely used for simulating biochemical reaction networks. SSA is able to capture the inherently intrinsic noise of the biological system, which is due to the discreteness of species population and to the randomness of their reciprocal interactions. However, SSA does not consider other sources of heterogeneity in biochemical reaction systems, which are referred to as extrinsic noise. Here, we extend two simulation approaches, namely, the integration-based method and the rejection-based method, to take extrinsic noise into account by allowing the reaction propensities to vary in time and state dependent manner. For both methods, new efficient implementations are introduced and their efficiency and applicability to biological models are investigated. Our numerical results suggest that the rejection-based method performs better than the integration-based method when the extrinsic noise is considered.
Microphase separation and the formation of ion conductivity channels in poly(ionic liquid)s: A coarse-grained molecular dynamics study
Authors: Weyman Alexander , Bier Markus , Holm Christian , Smiatek Jens
Published: February 2018

We study generic properties of poly(ionic liquid)s (PILs) via coarse-grained molecular dynamics simulations in bulk solution and under confinement. The influence of different side chain lengths on the spatial properties of the PIL systems and on the ionic transport mechanism is investigated in detail. Our results reveal the formation of apolar and polar nanodomains with increasing side chain length in good agreement with previous results for molecular ionic liquids. The ion transport numbers are unaffected by the occurrence of these domains, and the corresponding values highlight the potential role of PILs as single-ion conductors in electrochemical devices. In contrast to bulk behavior, a pronounced formation of ion conductivity channels in confined systems is initiated in close vicinity to the boundaries. We observe higher ion conductivities in these channels for increasing PIL side chain lengths in comparison with bulk values and provide an explanation for this effect. The appearance of these domains points to an improved application of PILs in modern polymer electrolyte batteries.
Wavelets solution of MHD 3-D fluid flow in the presence of slip and thermal radiation effects
Authors: Usman M. , Zubair T. , Hamid M. , Haq Rizwan Ul , Wang Wei
Published: February 2018

This article is devoted to analyze the magnetic field, slip, and thermal radiations effects on generalized three-dimensional flow, heat, and mass transfer in a channel of lower stretching wall. We supposed two various lateral direction rates for the lower stretching surface of the wall while the upper wall of the channel is subjected to constant injection. Moreover, influence of thermal slip on the temperature profile beside the viscous dissipation and Joule heating is also taken into account. The governing set of partial differential equations of the heat transfer and flow are transformed to nonlinear set of ordinary differential equations (ODEs) by using the compatible similarity transformations. The obtained nonlinear ODE set tackled by means of a new wavelet algorithm. The outcomes obtained via modified Chebyshev wavelet method are compared with Runge-Kutta (order-4). The worthy comparison, error, and convergence analysis shows an excellent agreement. Additionally, the graphical representation for various physical parameters including the skin friction coefficient, velocity, the temperature gradient, and the temperature profiles are plotted and discussed. It is observed that for a fixed value of velocity slip parameter a suitable selection of stretching ratio parameter can be helpful in hastening the heat transfer rate and in reducing the viscous drag over the stretching sheet. Finally, the convergence analysis is performed which endorsing that this proposed method is well efficient.
Tunnel-injected sub 290 nm ultra-violet light emitting diodes with 2.8% external quantum efficiency
Authors: Zhang Yuewei , Jamal-Eddine Zane , Akyol Fatih , Bajaj Sanyam , Johnson Jared M. , Calderon Gabriel , Allerman Andrew A. , Moseley Michael W. , Armstrong Andrew M. , Hwang Jinwoo , Rajan Siddharth
Published: February 2018

We report on the high efficiency tunnel-injected ultraviolet light emitting diodes (UV LEDs) emitting at 287 nm. Deep UV LED performance has been limited by the severe internal light absorption in the p-type contact layers and low electrical injection efficiency due to poor p-type conduction. In this work, a polarization engineered Al0.65Ga0.35N/In0.2Ga0.8N tunnel junction layer is adopted for non-equilibrium hole injection to replace the conventionally used direct p-type contact. A reverse-graded AlGaN contact layer is further introduced to realize a low resistance contact to the top n-AlGaN layer. This led to the demonstration of a low tunnel junction resistance of 1.9 × 10−3 Ω cm2 obtained at 1 kA/cm2. Light emission at 287 nm with an on-wafer peak external quantum efficiency of 2.8% and a wall-plug efficiency of 1.1% was achieved. The measured power density at 1 kA/cm2 was 54.4 W/cm2, confirming the efficient hole injection through interband tunneling. With the benefits of the minimized internal absorption and efficient hole injection, a tunnel-injected UV LED structure could enable future high efficiency UV emitters.
Time-dependent density functional theory description of total photoabsorption cross sections
Authors: Tenorio Bruno Nunes Cabral , Nascimento Marco Antonio Chaer , Rocha Alexandre Braga
Published: February 2018

The time-dependent version of the density functional theory (TDDFT) has been used to calculate the total photoabsorption cross section of a number of molecules, namely, benzene, pyridine, furan, pyrrole, thiophene, phenol, naphthalene, and anthracene. The discrete electronic pseudo-spectra, obtained in a L2 basis set calculation were used in an analytic continuation procedure to obtain the photoabsorption cross sections. The ammonia molecule was chosen as a model system to compare the results obtained with TDDFT to those obtained with the linear response coupled cluster approach in order to make a link with our previous work and establish benchmarks.
Probing the Hofmeister series beyond water: Specific-ion effects in non-aqueous solvents
Authors: Mazzini Virginia , Liu Guangming , Craig Vincent S. J.
Published: February 2018

We present an experimental investigation of specific-ion effects in non-aqueous solvents, with the aim of elucidating the role of the solvent in perturbing the fundamental ion-specific trend. The focus is on the anions: CH3COO−>F−>Cl−>Br−>I−>ClO4−>SCN− in the solvents water, methanol, formamide, dimethyl sulfoxide (DMSO), and propylene carbonate (PC). Two types of experiments are presented. The first experiment employs the technique of size exclusion chromatography to evaluate the elution times of electrolytes in the different solvents. We observe that the fundamental (Hofmeister) series is observed in water and methanol, whilst the series is reversed in DMSO and PC. No clear series is observed for formamide. The second experiment uses the quartz crystal microbalance technique to follow the ion-induced swelling and collapse of a polyelectrolyte brush. Here the fundamental series is observed in the protic solvents water, methanol, and formamide, and the series is once again reversed in DMSO and PC. These behaviours are not attributed to the protic/aprotic nature of the solvents, but rather to the polarisability of the solvents and are due to the competition between the interaction of ions with the solvent and the surface. A rule of thumb is proposed for ion specificity in non-aqueous solvents. In weakly polarisable solvents, the trends in specific-ion effects will follow those in water, whereas in strongly polarisable solvents the reverse trend will be observed. Solvents of intermediate polarisability will give weak specific-ion effects.
Nanoscale control of stripe-ordered magnetic domain walls by vertical spin transfer torque in La0.67Sr0.33MnO3 film
Authors: Wang Jing , Wu Shizhe , Ma Ji , Xie Lishan , Wang Chuanshou , Malik Iftikhar Ahmed , Zhang Yuelin , Xia Ke , Nan Ce-Wen , Zhang Jinxing
Published: February 2018

Stripe-ordered domains with perpendicular magnetic anisotropy have been intensively investigated due to their potential applications in high-density magnetic data-storage devices. However, the conventional control methods (e.g., epitaxial strain, local heating, magnetic field, and magnetoelectric effect) of the stripe-ordered domain walls either cannot meet the demands for miniaturization and low power consumption of spintronic devices or require high strength of the electric field due to the small value of the magnetoelectric effect at room temperature. Here, a domain-wall resistive effect of 0.1% was clarified in La0.67Sr0.33MnO3 thin films between the configurations of current in the plane and perpendicular to the plane of walls. Furthermore, a reversible nanoscale control of the domain-wall re-orientation by vertical spin transfer torque across the probe/film interface was achieved, where a probe voltage of 0.1 V was applied on a manganite-based capacitor. We also demonstrated that the stripe-ordered magnetic domain-wall re-orientation strongly depends on the AC frequency of the scanning probe voltage which was applied on the capacitor.
Fully suspended slot waveguide platform
Authors: Zhou Wen , Cheng Zhenzhou , Wu Xinru , Sun Xiankai , Tsang Hon Ki
Published: February 2018

A fully suspended slot waveguide (FSSWG) platform, including straight slot waveguides, 90° bends, high-Q racetrack resonators, and strip-to-slot mode converters, is demonstrated for broadband and low-loss operation in the mid-infrared spectral region. The proposed FSSWG platform has inherent merits of a broad spectral range of transparency which is limited only by the absorption of silicon, strong light–analyte interaction, good mechanical stability, and single lithography step fabrication process. By using asymmetric FSSWGs, the propagation loss, bending loss, and intrinsic optical Q factor are demonstrated to be 2.8 dB/cm, 0.15 dB/90°, and 12 600, respectively. The average conversion efficiency of a mode converter is 95.4% over a bandwidth of 170 nm and 97.0% at 2231 nm. The FSSWG platform would be promising for a long-range and cavity-enhanced light–analyte interaction.
Exciton-phonon coupling in a CsPbBr3 single nanocrystal
Authors: Ramade Julien , Andriambariarijaona Léon Marcel , Steinmetz Violette , Goubet Nicolas , Legrand Laurent , Barisien Thierry , Bernardot Frédérick , Testelin Christophe , Lhuillier Emmanuel , Bramati Alberto , Chamarro Maria
Published: February 2018

We have performed micro-photoluminescence measurements on a single CsPbBr3 nanocrystal (NC) with a size comparable to the Bohr diameter (7 nm). When the NC has an orthorhombic crystal symmetry, we observe an exciton fine structure composed of three peaks linearly polarized. We took advantage of the polarization properties of micro-photoluminescence to monitor in situ both the energy and linewidth of individual peaks when increasing temperature. We reveal that two regimes exist, at low and high temperature, which are dominated by acoustic or longitudinal optical phonon (Fröhlich term) couplings, respectively. The acoustic contribution does not change when the energy of the excitonic transition varies in the range of 2.46–2.62 eV, i.e., with NC sizes corresponding to this range. We find that line broadening is mainly ruled by the Fröhlich term, which is consistent with the polar nature of CsPbBr3.
Critical behavior of two-dimensional intrinsically ferromagnetic semiconductor CrI3
Authors: Lin G. T. , Luo X. , Chen F. C. , Yan J. , Gao J. J. , Sun Y. , Tong W. , Tong P. , Lu W. J. , Sheng Z. G. , Song W. H. , Zhu X. B. , Sun Y. P.
Published: February 2018

CrI3, which belongs to a rare category of two-dimensional (2D) ferromagnetic semiconductors, is of great interest for spintronic device applications. Unlike CrCl3 whose magnetism presents a 2D-Heisenberg behavior, CrI3 exhibits a larger van der Waals gap, smaller cleavage energy, and stronger magnetic anisotropy which could lead to a 3D magnetic characteristic. Hence, we investigate the critical behavior of CrI3 in the vicinity of magnetic transition. We use the modified Arrott plot and Kouvel-Fisher method and conduct critical isotherm analysis to estimate the critical exponents near the ferromagnetic phase transition. This shows that the magnetism of CrI3 follows the crossover behavior of a 3D-Ising behavior with mean field type interactions where the critical exponents β, γ, and δ are 0.323 ± 0.006, 0.835 ± 0.005, and 3.585 ± 0.006, respectively, at the Curie temperature of 64 K. We propose that the crossover behavior can be attributed to the strong uniaxial anisotropy and inevitable interlayer coupling. Our experiment demonstrates the applicability of crossover behavior to a 2D ferromagnetic semiconductor.
On the hypergeometric matrix functions of several variables
Authors: Dwivedi Ravi , Sahai Vivek
Published: February 2018

In this paper, we introduce Lauricella matrix functions of three variables as well as n-variables. We also define the matrix analog of the three variables and Srivastava’s triple hypergeometric functions. We examine the regions of convergence of Lauricella matrix functions and Srivastava’s triple hypergeometric matrix functions and also obtain their integral representations.
A two-layer model for buoyant inertial displacement flows in inclined pipes
Authors: Etrati Ali , Frigaard Ian A.
Published: February 2018

We investigate the inertial flows found in buoyant miscible displacements using a two-layer model. From displacement flow experiments in inclined pipes, it has been observed that for significant ranges of Fr and Re cos β/Fr, a two-layer, stratified flow develops with the heavier fluid moving at the bottom of the pipe. Due to significant inertial effects, thin-film/lubrication models developed for laminar, viscous flows are not effective for predicting these flows. Here we develop a displacement model that addresses this shortcoming. The complete model for the displacement flow consists of mass and momentum equations for each fluid, resulting in a set of four non-linear equations. By integrating over each layer and eliminating the pressure gradient, we reduce the system to two equations for the area and mean velocity of the heavy fluid layer. The wall and interfacial stresses appear as source terms in the reduced system. The final system of equations is solved numerically using a robust, shock-capturing scheme. The equations are stabilized to remove non-physical instabilities. A linear stability analysis is able to predict the onset of instabilities at the interface and together with numerical solution, is used to study displacement effectiveness over different parametric regimes. Backflow and instability onset predictions are made for different viscosity ratios.
Traveling wave solutions and conservation laws for nonlinear evolution equation
Authors: Baleanu Dumitru , Inc Mustafa , Yusuf Abdullahi , Aliyu Aliyu Isa
Published: February 2018

In this work, the Riccati-Bernoulli sub-ordinary differential equation and modified tanh-coth methods are used to reach soliton solutions of the nonlinear evolution equation. We acquire new types of traveling wave solutions for the governing equation. We show that the equation is nonlinear self-adjoint by obtaining suitable substitution. Therefore, we construct conservation laws for the equation using new conservation theorem. The obtained solutions in this work may be used to explain and understand the physical nature of the wave spreads in the most dispersive medium. The constraint condition for the existence of solitons is stated. Some three dimensional figures for some of the acquired results are illustrated.