bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrafine red P nanoconfined between expanded graphene sheets for high-performance lithium-ion batteries
Authors: Ruan Jiafeng , Pang Yuepeng , Luo Sainan , Yuan Tao , Peng Chengxin , Yang Junhe , Zheng Shiyou
Published: October 2018

An appropriate interlaminar distance of graphene sheets can ensure high loading and effective nanoconfinement of red P, causing high electrochemical performances.
Large-scale fabrication of BCN nanotube architecture entangled on a three-dimensional carbon skeleton for energy storage
Authors: Tabassum Hassina , Qu Chong , Cai Kunting , Aftab Waseem , Liang Zibin , Qiu Tianjie , Mahmood Asif , Meng Wei , Zou Ruqiang
Published: October 2018

The BCN nanotubes have been fabricated on melamine foam (MF) derived three dimensional (3D) nitrogen doped carbon skeleton, which exhibited high energy and power density for the SSC and ASC devices.
Correction: Initiation and future prospects of colloidal metal halide double-perovskite nanocrystals: Cs2AgBiX6 (X = Cl, Br, I)
Authors: Ravi Vikash Kumar , Singhal Nancy , Nag Angshuman
Published: October 2018

Correction for ‘Initiation and future prospects of colloidal metal halide double-perovskite nanocrystals: Cs2AgBiX6 (X = Cl, Br, I)’ by Vikash Kumar Ravi et al., J. Mater. Chem. A, 2018, DOI: 10.1039/c8ta06126b.
Electronic transport in CdSe nanoplatelet based polymer fibres
Authors: Miethe Jan F. , Schlosser Anja , Eckert J. Gerrit , Lübkemann Franziska , Bigall Nadja C.
Published: October 2018

Hybrid fibres consisting of CdSe nanoplatelets in a polymer shell are prepared and charge carrier transport across these structures is proven photoelectrochemically.
Kinetics of dye regeneration in liquid electrolyte unveils efficiency of 10.5% in dye-sensitized solar cells
Authors: Krishna Jonnadula Venkata Suman , Krishna Narra Vamsi , Chowdhury Towhid H. , Singh Suryaprakash , Bedja Idriss , Islam Ashraful , Giribabu Lingamallu
Published: October 2018

We have designed and synthesised four novel porphyrin sensitizers for dye-sensitized solar cell applications and shown power conversion efficiency of 10.5%.
Highly stable perovskite nanogels as inks for multicolor luminescent authentication applications
Authors: Wang Hui , Yin Xiong , Wang Leyu
Published: October 2018

Full-spectral emissive perovskite nanogels present outstandingly improved photo-stability, thermal-stability and humidity-stability for anti-counterfeiting two-dimensional barcode application.
Long non-coding RNA linc-ITGB1 promotes cell proliferation, migration, and invasion in human hepatoma carcinoma by up-regulating ROCK1
Authors: Huang Lei , Li Xinyu , Gao Weijie
Published: October 2018

Background: Linc-ITGB1 is a newly identified long non-coding RNA (lncRNA) involved in the regulation of cell migration and invasion of gallbladder cancer cell lines, while its involvement in human hepatoma carcinoma (HCC) is unknown. Methods: In the present study, HCC patient tumor tissues, adjacent healthy tissues and whole blood were collected from both HCC patients and healthy controls. Expression of LINC-ITGB1 was examined by qRT-PCR. Diagnostic value of serum LINC-ITGB1 for HCC was evaluated by receiver operating characteristic (ROC) curve analysis. Correlation between the serum LINC-ITGB1 and basic clinical information of patients was analyzed by chi-square test. LINC-ITGB1 overexpression HCC cell lines were established and the effects on cell proliferation, migration, and invasion were explored by CCK-8 assay and Transwell assay. Effects of LINC-ITGB1 overexpression on Rho-associated, coiled-coil-containing protein kinase 1 (ROCK1) expression were investigated by Western blot. Results: We found that LINC-ITGB1 was up-regulated in tumor tissues than in adjacent healthy tissues. Serum levels of LINC-ITGB1 were higher in HCC patients than in healthy controls. Serum levels of LINC-ITGB1 were significantly correlated with tumor size and distant tumor metastasis. LINC-ITGB1 overexpression promoted the proliferation, migration, and invasion of HCC cells and the expression of ROCK1. ROCK1 inhibitor reduced the effects of LINC-ITGB1 overexpression on cell proliferation, migration, and invasion. Conclusion: We conclude that lncRNA LINC-ITGB1 can promote the proliferation, migration, and invasion of HCC cells by up-regulating ROCK1.
Prediction of energy consumption for new electric vehicle models by machine learning
Authors: Fukushima Arika , Yano Toru , Imahara Shuichiro , Aisu Hideyuki , Shimokawa Yusuke , Shibata Yasuhiro
Published: October 2018

Recommending suitable charging spots to drivers on expressways for both charging equipment and electric vehicles (EVs) is an important issue for the spread of EVs. Therefore, the authors developed a recommendation system based on the prediction of the driving ranges of multiple EVs running on expressways. Recommendations are calculated from the energy consumption predicted by data‐driven models constructed by actual data on EV trips. In authors’ system, prediction models for popular EV models were constructed with high accuracy. However, the accuracy of prediction is lower for new EV models than for the popular EV models, because the number of trips of new EV models running on the expressway is limited. To solve this problem, the authors propose a new transfer learning method, a type of machine learning that constructs prediction models using other sufficient data on popular EV models. They also evaluated their proposed method using the data on actual EV trips. As a result, the rate of prediction error of authors’ proposed method was reduced by about 30% from that the conventional method. The authors’ proposed method has the potential to predict the energy consumption for new EV models with higher accuracy.
Smart and self‐organised routing algorithm for efficient IoT communications in smart cities
Authors: Hamrioui Sofiane , Hamrioui Camil Adam Mohamed , Lioret Jaime , Lorenz Pascal
Published: October 2018

Internet of Things (IoT) does not stop integrating an important number of components and objects that are characterised by their complexity and heterogeneity. Such constraints make the existing routing protocols unsuitable for IoT communications in a smart cities environment. To accomplish all the expected tasks and satisfy the user services, it is important to guarantee a quality of communication that answers to the requirements of smart cities applications in terms of data and processing. This study addresses the problem of the performance degradation of IoT communications in smart cities and proposes a new routing algorithm to improve them. The proposed algorithm is called SSRA (smart and self‐organised routing algorithm), which can select the best route for the packets. SSRA allows a self‐organising routing process according to a new situation of the network and devices parameters recently detected. When using SSRA, the communication records an improvement in performance in terms of packet delivery rate, throughput, end‐to‐end delay and overhead packets. SSRA extends also the devices lifetime by allowing fair and efficient energy consumption.
GVANET project: an efficient deployment of a self‐powered, reliable and secured VANET infrastructure
Authors: Ali Qutaiba Ibrahim
Published: October 2018

The aim of this study is to describe the authors' efforts to accomplish the green vehicular ad hoc network (GVANET) project. The goal is to realise the concept of a self ‘renewably’ powered communication infrastructure appropriate for intelligent transportation systems. The work in this project was started in 2009 with the intention of representing the necessary steps must be taken to achieve such system and to declare the usefulness of adopting environmental energy resources in building mission critical systems. The other objectives of this project are presenting a reasonably cost, reliable, secured and easy to install communication infrastructure. Their plan to implement the GVANET was achieved after passing two design levels: device level and system level. In the device level, they suggest that the architecture of a road side unit (RSU) must be enhanced to maintain its robustness and availability against the different failure events which may occur due to many reasons such as power supply shortage or denial of service attacks. The design philosophy in the system level concentrates on building a sustainable, secured, reliable and scalable communication infrastructure to solve the different systematic problems raised when implementing the RSU as a member of the GVANET.
Temperature rise test and analysis of high current switchgear in distribution system
Authors: Xia Haotian , Guan Yonggang , Yu Zhanqing , Cai Suxiong , Wang Xiaorui , Peng Zhaowei , Gao Shisen , Huang Zerong
Published: October 2018

As the load of the power system continues to increase, the capacity of switchgear climbs, resulting in that the overheating problems becoming more serious. In order to realise the monitoring of the temperature of the switchgear, the authors need to conduct a thorough analysis of the temperature rise principle of the switchgear firstly. For the purpose of getting the detailed temperature distribution in the switchgear, a series of temperature rise tests were carried out based on the KYN28A‐12(Z) overhead line switchgear, and the data were analysed and compared in detail to summarise the factors that affect the temperature distribution in the switchgear.
Case‐based power transformer diagnose model using nonlinear mapping of oil chromatography
Authors: Zheng Yiming , Yao Hui , Sheng Jun , He Wenlin , Sun Xiang , Wang Wenhao , Zhan Jiangyang
Published: October 2018

In this study, a case‐based diagnostic model of a power transformer for oil chromatography is proposed. A nonlinear normalised mapping method is proposed for achieving ideal distribution characteristics of oil chromatogram gas in the case base. A similarity degree algorithm is proposed to calculate the similarity degree in the target spatial domain between the case to be diagnosed and the cases in the case base. A threshold method is proposed to determine the number of similar cases. Also, a method for calculating the weight of the diagnosis result according to the case distribution in the case base is proposed. The diagnostic method proposed is used to deploy the diagnostic system on the Internet. Defeat diagnosis conclusions of two transformers by the method and system in this paper are consistent with the disintegration results. It can be concluded that the proposed method has important practical application value in engineering.
Analysis and assessment standards of power stability of multi‐send HVDC systems
Authors: Xu Zheling , Xu Zheng , Xiao Liang
Published: October 2018

The asynchronously interconnected Yunnan Power Grid is a typical multi‐send HVDC system. So far, research on systems with multiple high voltage direct current (HVDC) links is mainly focused on multi‐infeed HVDC systems, and the assessment standards for power stability of multi‐send HVDC systems have not been discussed yet. In this study, firstly the quasi‐steady‐state model of a two‐send HVDC system is built and an analysis of power stability based on the maximum power curve is given. Secondly, the relationships between power stability and two indices (Multi‐infeed Effective Short‐circuit Ratio and the Multi‐infeed Interaction Factor) are discussed. Lastly, the assessment standards for power stability of multi‐send HVDC systems are proposed and a case study of Yunnan Power Grid is presented, which may provide useful instructions for the planning process of multi‐send HVDC systems.
Whipping IC 63/IC 59
Authors: Andrews H. , Peeters E. , Tielens A. G. G. M. , Okada Y.
Published: October 2018

Context. IC 63 and IC 59 are a pair of cometary-shaped nebulae in the vicinity of the star γCas (also known as Tsih, “the Whip”). Both nebulae have very different optical appearances, despite the fact that both objects lie at similar projected distances from the star: IC 63 shows bright rims and filaments, while IC 59 looks more homogeneous and faint.

Aims. We aim to perform a general description of the two nebulae from an observational standpoint in order to study the physical conditions at the UV-illuminated surfaces of these objects.

Methods. We used the available data on both nebulae taken with Spitzer and Herschel to study the infrared emission at the tip of both clouds, and derive the intensity of the UV radiation field. Using the photodetector array camera and spectrometer (PACS) in line spectroscopy mode, we obtained the intensity of the cooling lines [C II] 157 μm and [O I] 63 μm, and we used these to estimate the density in these regions. Excitation diagrams of molecular hydrogen were obtained to derive the gas temperature. We also used [C II] 157 μm velocity maps of IC 59 taken with German REceiver for Astronomy at Terahertz frequencies (GREAT) on board SOFIA to explore the gas dynamics in this nebula.

Results. We find that the IR emission from polycyclic aromatic hydrocarbons (PAHs) is very similar at the tip of both nebulae. Even though it varies in intensity between the two, the derived PAH band ratios are remarkably similar. These ratios are similar to those found in the more shielded regions of other nebulae such as NGC 7023 and NGC 2023. Regarding the physical conditions, we get that while in IC 63 the intensity of the UV field, G0, is a factor of approximately ten higher than in IC 59, the density n at the tip of IC 59 is lower than in IC 63 by a similar factor. For both objects we derive G0 values significantly lower than what previous works have so far assumed. Comparison with other reflection nebulae photo-dissociation regions (PDRs) and known correlations support our claim that both IC 63 and IC 59 are low-UV irradiated environments.

Conclusions. We conclude that the tips of IC 63 and IC 59 are about three and five times farther away from the star than their respective projected distances. The similarity of the mid-infrared emission between the two nebulae is consistent not only with both objects being overdensities within the same region around γCas, but it is also consistent with the similar G0/n and ionization parameters, which altogether rule the evolution of the hydrogenation and ionization level of the emitting population of PAHs. Finally, regarding the kinematics of the material in IC 59, we find evidence of photo-evaporation due to the incident radiation from γCas.
Sharpening up Galactic all-sky maps with complementary data
Authors: Müller Ancla , Hackstein Moritz , Greiner Maksim , Frank Philipp , Bomans Dominik J. , Dettmar Ralf-Jürgen , Enßlin Torsten
Published: October 2018

Context. Galactic all-sky maps at very disparate frequencies, such as in the radio and γ-ray regime, show similar morphological structures. This mutual information reflects the imprint of the various physical components of the interstellar medium.

Aims. We want to use multifrequency all-sky observations to test resolution improvement and restoration of unobserved areas for maps in certain frequency ranges. For this we aim to reconstruct or predict from sets of other maps all-sky maps that, in their original form, lack a high resolution compared to other available all-sky surveys or are incomplete in their spatial coverage. Additionally, we want to investigate the commonalities and differences that the interstellar medium components exhibit over the electromagnetic spectrum.

Methods. We built an n-dimensional representation of the joint pixel-brightness distribution of n maps using a Gaussian mixture model and investigate how predictive it is. We study the extend to which one map of the training set can be reproduced based on subsets of other maps?

Results. Tests with mock data show that reconstructing the map of a certain frequency from other frequency regimes works astonishingly well, predicting reliably small-scale details well below the spatial resolution of the initially learned map. Applied to the observed multifrequency data sets of the Milky Way this technique is able to improve the resolution of, for example, the low-resolution Fermi-LAT maps as well as to recover the sky from artifact-contaminated data such as the ROSAT 0.855 keV map. The predicted maps generally show less imaging artifacts compared to the original ones. A comparison of predicted and original maps highlights surprising structures, imaging artifacts (fortunately not reproduced in the prediction), and features genuine to the respective frequency range that are not present at other frequency bands. We discuss limitations of this machine learning approach and ideas how to overcome them. In particular, with increasing sophistication of the method, such as introducing more internal degrees of freedom, it starts to internalize imaging artifacts.

Conclusions. The approach is useful to identify particularities in astronomical maps and to provide detailed educated guesses of the sky morphology at not yet observed resolutions and locations.
Possible substellar companions in low-mass eclipsing binaries: GU Bootis and YY Geminorum
Authors: Wolf M. , Kučáková H. , Zasche P. , Vraštil J. , Hoňková K. , Hornoch K. , Lehký M. , Mašek M. , Šmelcer L. , Tylšar M. , Novák R. , Červinka L. , Bělík M.
Published: October 2018

We present the next results of our long-term observational project to analyze the variations in the orbital periods of low-mass eclipsing binaries. About 70 new precise mid-eclipse times recorded with a CCD were obtained for two eclipsing binaries with short orbital periods: GU Boo (P = 0.​d49) and YY Gem (0.​d81). Observed-minus-calculated diagrams of the stars were analyzed using all reliable timings, and new parameters of the light-time effect were obtained. We derived for the first time or improved the short orbital periods of possible third bodies of 11 and 54 years for these low-mass binaries, respectively. We calculated that the minimum masses of the third components are close to 50 MJup, which corresponds to the mass of brown dwarfs. The multiplicity of these systems also plays an important role in the precise determination of their physical parameters.
The XXL Survey
Authors: Pacaud F. , Pierre M. , Melin J.-B. , Adami C. , Evrard A. E. , Galli S. , Gastaldello F. , Maughan B. J. , Sereno M. , Alis S. , Altieri B. , Birkinshaw M. , Chiappetti L. , Faccioli L. , Giles P. A. , Horellou C. , Iovino A. , Koulouridis E. , Le Fèvre J.-P. , Lidman C. , Lieu M. , Maurogordato S. , Moscardini L. , Plionis M. , Poggianti B. M. , Pompei E. , Sadibekova T. , Valtchanov I. , Willis J. P.
Published: October 2018

Context. We present an estimation of cosmological parameters with clusters of galaxies.

Aims. We constrain the Ωm, σ8, and w parameters from a stand-alone sample of X-ray clusters detected in the 50 deg2 XMM-XXL survey with a well-defined selection function.

Methods. We analyse the redshift distribution of a sample comprising 178 high signal-to-noise ratio clusters out to a redshift of unity. The cluster sample scaling relations are determined in a self-consistent manner.

Results. In a lambda cold dark matter (ΛCDM) model, the cosmology favoured by the XXL clusters compares well with results derived from the Planck Sunyaev-Zel’dovich clusters for a totally different sample (mass/redshift range, selection biases, and scaling relations). However, with this preliminary sample and current mass calibration uncertainty, we find no inconsistency with the Planck CMB cosmology. If we relax the w parameter, the Planck CMB uncertainties increase by a factor of ~10 and become comparable with those from XXL clusters. Combining the two probes allows us to put constraints on Ωm = 0.316 ± 0.060, σ8 = 0.814 ± 0.054, and w = −1.02 ± 0.20.

Conclusions. This first self-consistent cosmological analysis of a sample of serendipitous XMM clusters already provides interesting insights into the constraining power of the XXL survey. Subsequent analysis will use a larger sample extending to lower confidence detections and include additional observable information, potentially improving posterior uncertainties by roughly a factor of 3.
Biomass and biofuels
Authors: Fiala Marco , Nonini Luca
Published: October 2018

Biomass includes all materials that contain organic carbon bound in the chemical structure of molecules, resulting from the chlorophylline photosynthesis, carried out by autotrophies organisms. Lots of biomass from agricultural, agri-food and forestry sectors can be used for energy purposes, representing an essential renewable energy source that, if appropriately managed, can help to reduce the negative environmental impacts arising from the exploitation of fossil fuels. The possibility of using biomass for a speciﬁc production process mainly depends on its physical and chemical properties. This paper is organized in two sections: in the ﬁrst one, the most important biomass used worldwide for energy generation (thermal energy and/or electric energy), as well as its properties, are described. In the second one, the main biomass-to-energy processes (thermochemical and biochemical conversions) are shortly explained. Finally, some emerging techniques (such as bio-methane and bio-hydrogen production) are discussed in more detail.
Enhancement method for assignments of staff in multiple events
Authors: Diponegoro Ahmad
Published: October 2018

A problem of staff assignment in an organization with multiple assignments of scheduled events is addressed here. The objective is to propose an efficient and practical approach for enhancing a given policy of staff assignments to attain a more efficient operation. To address the problem, a multi-period assignment model formulation is employed here. Using this approach, an efficient heuristic method is devised to obtain enhancements of any given solution policy. A numerical example is provided for clarity in implementing the proposed method. This research is expected to provide a meaningful contribution to managing staff assignments in various types of organizations.
Causal Therapies in Mucopolysaccharidoses: Enzyme Replacement Therapy
Authors: Vartanyan Ara , Montaño Adriana
Published: October 2018

Enzyme replacement therapy (ERT) for mucopolysaccharidoses (MPS) is the treatment of choice for patients, since it specifically addresses the underlying cause of the disease. Intravenous weekly infusions of recombinant enzymes for MPS I, II, IVA, VI, and VII have proven to be safe and efficacious for somatic symptoms. ERT has been shown to decrease urinary glycosaminoglycan levels and organomegaly, while improving stamina of patients, respiratory function, and quality of life. Although early administration of ERT optimizes outcomes, adult patients still benefit from treatment. ERT has been successfully used as combination therapy with hematopoietic stem cell transplant for patients with MPS I and MPS II, improving patient's cognitive outcomes. Although patients can receive benefit from ERT, current challenges include lack of improvement of neurological manifestations, limited effect on bone disease, development of immune response toward the infused enzyme, and high cost. We will discuss the milestones achieved by intravenous ERT for MPS diseases as well as the current challenges.
Innovative Treatments for Mucopolysaccharidoses
Authors: Lagler Florian
Published: October 2018

Mucopolysaccharidoses (MPSs) are caused by deficiency of specific lysosomal enzymes that affect the degradation of mucopolysaccharides or glycosaminoglycans. Since more than 15 years enzyme replacement therapies are available for an increasing number of MPSs. These therapies together with hematopoietic stem cell transplantation today are the gold standard of causal treatment in MPS. Despite confirmed efficacy, both do not cure these severe conditions. In this article, we discuss the limitations of established and promises of emerging therapies. The limitations of intravenous enzyme replacement and cell therapy can be summarized as immune reactions against the therapeutic molecules/cells and the failure to restore enduring and sufficient enzyme concentration in all relevant tissues. Accordingly, innovative approaches comprise small molecules and encapsulated cells that do not activate antitherapeutic immune reactions, several gene therapy approaches that aim for sustained enzyme expression, and new enzymes that penetrate blood–brain and other barriers for drug distribution. This article provides an update on the state of development of these new therapies and highlights enduring challenges.
All-Polyethylene Tibial Components in Total Knee Replacement: Early Failures
Authors: Alhifzi Zaki Suliman , Khoja Yousef Tawfik , Wood Gavin C.
Published: October 2018

In total primary knee replacement surgery, the use of all-polyethylene tibial (APT) components has many advantages, including no backside wear and no linear dissociation. In addition, the greater polyethylene thickness permits more conservative bone resection compared with that for metal-backed components, with a lower unit cost and similar functional results. Thus, the use of an APT in primary total knee arthroplasty remains an attractive option. This is a review of 158 patients who underwent primary knee replacement using APT components from a single manufacturer. Data collection included age, American Society of Anesthesiology physical status classification, body mass index (BMI), type of deformity, the presence of diabetes mellitus, rate of revision, and characteristics associated with early failure of the components. Average follow-up time was 40 months. The revision rate for any reason was 5.6%, and the average BMI in revision cases was 37.6. Patients with a higher BMI (≥ 37.6) were significantly more likely to require revision surgery than patients with a lower BMI (p = 0.04). In our sample, high BMI was a contributing factor for early failures in total knee replacements using an APT component. Generally, polyethylene tibial components used for primary knee replacements are safe and effective, with good outcomes and subsequent lower costs to the health care system.
Severe Troponin I Elevation and Myocardial Dysfunction in a Child with Scorpion Sting
Authors: Yildizdas Dincer , Horoz Ozden , Arslan Didar , Varan Celal , Erdem Sevcan , Yılmaz Hayri , Aslan Nagehan
Published: October 2018

Background Scorpion sting is a common medical problem and major cause of mortality and morbidity in many countries. The symptoms of envenomation are more severe in the pediatric population. The clinical manifestations of scorpion envenomation appear by activation of sympathetic and parasympathetic nervous system. Envenomation can cause multiorgan dysfunction and death.

Case Presentation and Findings In this case report, we present a pediatric patient from Adana, Southeast Anatolia, with severe scorpion envenomation with Leiurus abdullahbayrami which is an especially dangerous species for children. Severe systolic dysfunction was detected by echocardiography. Troponin I levels elevated significantly and rapidly responded to three doses of antivenom therapy.

Conclusion Early echocardiographic examination is an important procedure for patients with scorpion envenomation. Troponin I is a significant parameter to monitor the degree of cardiac injury. Antivenom therapy is the only recommended specific therapy for children with severe scorpion envenomation due to Leiurus abdullahbayrami. Abnormal echocardiography findings may require repeated doses of scorpion antivenom.
A periodic magnetic field as a special environment for scientific research created by rotating permanent magnet pairs
Authors: Liu Ya-Li , Li Da-Wei , He Jin , Xie Xu-Zhuo , Chen Da , Yan Er-Kai , Ye Ya-Jing , Yin Da-Chuan
Published: October 2018

A magnetic field is an often-encountered physical environment that can affect many processes, including chemical, physical, and biochemical processes. Utilization of magnetic fields is thus very helpful in a wide variety of applications, such as scientific research in various disciplines, materials processing (e.g., crystal growth and separation) in industry, and nuclear fusion. There are many different types of magnetic fields generated by different magnets, such as superconducting magnets, electromagnets, hybrid magnets, pulsed magnets, and permanent magnets. In this paper, we introduce a newly designed periodic magnetic field generated by rotating permanent magnet pairs. Preliminary tests showed that the periodic magnetic field is valuable in water evaporation, silver deposition, and protein crystallization. Apparently, in such a new environment that can generate a periodic magnetic field, a periodic force field will also be simultaneously generated on the sample. Further work shall be carried out to explore the potential applications of this magnetic field.
Linear analysis of traveling sheet electron beam in sine waveguide tubes
Authors: Lei Xia , Li Qian , Wu Gangxiong , Ding Chong , Jiang Xuebing , Fang Shuanzhu , Xu Jin , Yin Hairong , Yue Lingna , Wei Yanyu
Published: October 2018

A theoretical model is proposed for linear analysis of the beam–wave interaction in a sine waveguide (SWG) with slow-wave structure. The field expressions and “hot” dispersion equation are obtained by means of field matching. The ohmic loss and attenuation constant due to imperfect conductors are also derived using the theoretical model. Moreover, the effects of voltage, current, beam thickness, period, and oscillation amplitude on the linear gain and bandwidth are calculated. The results indicate a peak gain and 3-dB bandwidth of 6.82 dB/cm and 19.5%, respectively, for a 0.22-THz SWG traveling-wave tube upon selecting reasonable structural parameters and electron-beam dimensions. Furthermore, by considering the ohmic losses for the finite conductivities of 5.8 × 107 S/m and 2.2 × 107 S/m, the theoretical results are compared with those of particle-in-cell simulations performed using Computer Simulation Technology Particle Studio.
Coupled wave equation study of non-collinear phase-matching second harmonic generation and nonlinear Cherenkov radiation generated on the surface of bulk lithium niobate crystals doped with magnesium medium
Authors: Wang Xiaojing , Ren Huaijin , Shen Jianqiang , Wang Gang , Chen Xianfeng , He Jun
Published: October 2018

In this article, on the basis of our previous research on bandwidth of non-collinear phase-matching second harmonic generation (SHG) and nonlinear Cherenkov radiation (NCR) generated on the boundary of bulk nonlinear crystal, we demonstrated theoretically the coupled wave equation of SHG generated by a Gaussian beam on the boundary of 5%/mol MgO:LiNbO3. Using the Fourier-transform technique, we solved this coupled wave equation. The results can explain theoretically the generation mechanism of two different experimental phenomena which corresponded to non-collinear phase-matching SHG under anomalous-dispersion-like dispersion condition and nonlinear NCR under normal dispersion condition, respectively. The theoretical results show a good agreement with the experimental data. This work can provide theoretical fundamental for more complicated research on the boundary of nonlinear media.
Efficient determination of synchronization domains from observations of asynchronous dynamics
Authors: Rosenblum Michael , Pikovsky Arkady
Published: October 2018

We develop an approach for a fast experimental inference of synchronization properties of an oscillator. While the standard technique for determination of synchronization domains implies that the oscillator under study is forced with many different frequencies and amplitudes, our approach requires only several observations of a driven system. Reconstructing the phase dynamics from data, we successfully determine synchronization domains of noisy and chaotic oscillators. Our technique is especially important for experiments with living systems where an external action can be harmful and shall be minimized.
Numerical investigation of effects of curvature and wettability of particles on heterogeneous condensation
Authors: Wang Zijing , Qin Fenghua , Luo Xisheng
Published: October 2018

The incipient process of water vapor condensation around an insoluble nanoscale particle is studied by a molecular dynamics method, and the emphasis is placed on the effects of particle surface curvature and wettability. With a high initial saturation, two different linear nucleation stages are observed. At the first stage, clusters are formed by the water molecules adsorbed on the surface such that the nucleation rate is significantly affected by both water molecule flux toward the surface and adsorption probability. The former decreases with the surface curvature, and the latter is in proportion to the wettability. At the second stage, the nucleation rate is enhanced by the contribution of homogeneous clusters adsorbed to the surface and reduced by cluster merging because of the space limitation on small particles. As a result, the nucleation rate is basically not affected by the particle size. The average size of clusters keeps constant for a while, then starts to grow with a gradually increased growth rate. It is concluded that both curvature and wettability of the particle surface promote the cluster growing.
Conduction mechanisms at distinct resistive levels of Pt/TiO2-x/Pt memristors
Authors: Michalas L. , Stathopoulos S. , Khiat A. , Prodromakis T.
Published: October 2018

Resistive random access memories (RRAMs) are considered as key enabling components for a variety of emerging applications due to their capacity to support multiple resistive states. Deciphering the underlying mechanisms that support resistive switching remains to date a topic of debate, particularly for metal-oxide technologies, and is very much needed for optimizing their performance. This work aims to identify the dominant conduction mechanisms during switching operation of Pt/TiO2-x/Pt stacks, which is without a doubt one of the most celebrated ones. A number of identical devices were accordingly electroformed for acquiring distinct resistive levels through a pulsing-based and compliance-free protocol. For each obtained level, the switching current-voltage (I-V) characteristics were recorded and analyzed in the temperature range of 300 K–350 K. This allowed the extraction of the corresponding signature plots revealing the dominant transport mechanism for each of the I-V branches. Gradual (analogue) switching was obtained for all cases, and two major regimes were identified. For the higher resistance regime, the transport at both the high and low resistive states was found to be interface controlled due to Schottky emission. As the resistance of devices reduces to lower levels, the dominant conduction changes from an interface to the core-material controlled mechanism. This study overall supports that engineering the metal-oxide/metal electrode interface can lead to tailored barrier modifications for controlling the switching characteristics of TiO2 RRAM.
Superconductivity induced by hydrostatic pressure effect in LaO0.5F0.5Bi(S0.9Se0.1)2
Authors: Kondo Katsuo , Kase Naoki , Watanabe Shigefumi , Miyakawa Nobuaki
Published: October 2018

Electrical resistivity of LaO0.5F0.5Bi(S0.9Se0.1)2 have been measured at a temperature range of 2.8 ∼ 300 K by applying several hydrostatic pressures. Pressure-induced superconducting phase was observed above a pressure P of 0.85 GPa and Tc increased from 2.86 K to 8.42 K. The sudden increase of Tc in LaO0.5F0.5Bi(S0.9Se0.1)2 results from the structural phase transition from tetragonal (P4/nmm) to monoclinic (P21/m). Structural phase transition pressure Pc of LaO0.5F0.5Bi(S0.9Se0.1)2 is higher than that of LaO0.5F0.5BiS2. The increase of Pc is ascribed to the suppression of the displacement parameter of the in-plane chalcogen site induced by chemical pressure of Se-substitution.
Transport properties of transition-metal doped BiS2-based superconductors
Authors: Kase Naoki , Kondo Katsuo , Koike Masao , Watanabe Shigefumi , Miyakawa Nobuaki
Published: October 2018

We performed the electrical resistivity and thermoelectric power measurements of the polycrystalline La0.8Ti0.2OBi(S1-xSex)2. The electrical resistivity of La0.8Ti0.2OBi(S0.7Se0.3)2 at room temperature dramatically decreases, and the temperature dependence shows metallic-like behavior. From the electrical resistivity, superconductivity was not observed in La0.8Ti0.2OBi(S1-xSex)2 above 2.8 K. The value of thermoelectric power S(300 K) of La0.8Ti0.2OBiSSe was about -65 μV/K, which is comparable to that of the polycrystalline LaOBiS2. The value of S(300 K) of La0.8Ti0.2OBiS2 was about -115 μV/K. These power factors are relatively smaller than that of the polycrystalline LaOBiSSe.
Charged nanorods at heterogeneously charged surfaces
Authors: Naji Ali , Hejazi Kasra , Mahgerefteh Elnaz , Podgornik Rudolf
Published: October 2018

We study the spatial and orientational distribution of charged nanorods (rodlike counterions) as well as the effective interaction mediated by them between two plane-parallel surfaces that carry fixed (quenched) heterogeneous charge distributions. The nanorods are assumed to have an internal charge distribution, specified by a multivalent monopolar moment and a finite quadrupolar moment, and the quenched surface charge is assumed to be randomly distributed with equal mean and variance on the two surfaces. While equally charged surfaces are known to repel within the traditional mean-field theories, the presence of multivalent counterions has been shown to cause attractive interactions between uniformly charged surfaces due to the prevalence of strong electrostatic couplings that grow rapidly with the counterion valency. We show that the combined effects due to electrostatic correlations (caused by the coupling between the mean surface field and the multivalent, monopolar, charge valency of counterions) as well as the disorder-induced interactions (caused by the coupling between the surface disorder field and the quadrupolar moment of counterions) lead to much stronger attractive interactions between two randomly charged surfaces. The interaction profile turns out to be a nonmonotonic function of the intersurface separation, displaying an attractive minimum at relatively small separations, where the ensuing attraction can exceed the maximum strong-coupling attraction (produced by multivalent monopolar counterions between uniformly charged surfaces) by more than an order of magnitude.
Decomposability of linear maps under tensor powers
Authors: Müller-Hermes Alexander
Published: October 2018

Both completely positive and completely copositive maps stay decomposable under tensor powers, i.e., under tensoring the linear map with itself. But are there other examples of maps with this property? We show that this is not the case: Any decomposable map, that is neither completely positive nor completely copositive, will lose decomposability eventually after taking enough tensor powers. Moreover, we establish explicit bounds to quantify when this happens. To prove these results, we use a symmetrization technique from the theory of entanglement distillation and analyze when certain symmetric maps become non-decomposable after taking tensor powers. Finally, we apply our results to construct new examples of non-decomposable positive maps and establish a connection to the positive partial transpose squared conjecture.
Morphology-induced spin frustration in granular BiFeO3 thin films: Origin of the magnetic vertical shift
Authors: Modarresi H. , Menéndez E. , Lazenka V. V. , Pavlovic N. , Bisht M. , Lorenz M. , Petermann C. , Grundmann M. , Hardy A. , Van Bael M. K. , Van Bael M. J. , Vantomme A. , Temst K.
Published: October 2018

Pronounced room temperature vertical shifts in the magnetic hysteresis loops of granular, highly polycrystalline and ferromagnetic-like BiFeO3 thin films are observed upon field-cooling from a temperature above the Néel temperature of bulk BiFeO3. This is ascribed to the interplay between the preferential alignment, established by the field-cooling process, of the net magnetic moment, which arises from uncompensated antiferromagnetic spins, and the pinning of a fraction of these spins at the particle boundaries. Conversely, field-cooling of an epitaxially grown BiFeO3 film results in no vertical shift, confirming the effective role played by the particle boundaries (i.e., morphology) of the granular-like BiFeO3 films in the process of spin frustration.
Aerothermodynamic effects of controlled heat release within the hypersonic shock layer around a large angle blunt cone
Authors: Deep Sneh , Jagadeesh G.
Published: October 2018

Effects of controlled heat addition into the high temperature, chemically reacting shock layer of a large angle (60°) blunt cone with a spherical nose have been experimentally investigated. The exothermic oxidation of ablated chromium from the surface of the cone at hypersonic Mach numbers triggers the heat release process. A conical skirt with a base diameter of 70 mm and a semi-apex angle of 30°, culminating into a nose of radius 30 mm, has been used as the test model. An in-house hypersonic free-piston driven shock tunnel facility, HST3, was used for the experiments at a stagnation enthalpy of 6.31 MJ/kg and a freestream Mach number of 9.84. The temperature distribution in the shock layer was experimentally measured by the two-color ratio pyrometry technique, using a Digital Single Lens Reflex (DSLR) camera as a pyrometer. The temperature field was corrected for discrete radiative line emissions obtained through emission spectroscopy. Surface heat flux measurements were taken using carefully calibrated thin film platinum heat transfer gauges mounted on an insulating Macor substrate. Shock stand-off distances were measured through Schlieren imaging of the flow using a high-speed camera at 20 000 frames per second, and also by a new intensity-scan based method using the processed color image from the DSLR camera. Calculations showed a 173 K rise in the temperature of the gas layer in the stagnation region due to chromium oxidation. The net surface heat flux on the blunt cone was also found to increase by about 31 W/cm2. The shock stand-off distance, as ascertained from Schlieren images, increased from about 3.82 mm (±1.4%) to 4.45 mm (±1.5%), a 17% rise. Analytical calculations, taking chromium oxidation reaction kinetics into consideration, to relate the total exothermic heat release to its distribution into various processes demonstrated that chromium oxidation releases about 78 W/cm2 energy in the stagnation region of the shock layer. 1.9% of this energy increases the temperature of the gas layer, 40% is convected back into the airframe, 0.4% is lost from the rear of the Macor substrate by conduction, and about 8% is radiated into the model. The remaining 50% of the heat was used up in pushing the shock layer away from the body by raising its density, thereby increasing shock stand-off distance.
Morphology dependent resonance modes in highly porous TiO2 microspheres
Authors: Kalyan Imon , Krishnamurthy C. V.
Published: October 2018

Micro and nano structures of titanium dioxide (TiO2) are well-known for their photocatalytic application. High surface area and high light scattering efficiency in such structures enhance their photocatalytic activity. The present work explores the possibility of enhancing photocatalytic activity through mesoporous TiO2 spheres by exploiting the coexistence of high porosity and morphology dependent resonance (MDR) modes. A controlled synthesis of TiO2 spheres with nano-crystalline grains of anatase phase and high surface area of about 96 m2/g has been successfully accomplished leading to mesoporous particles with uniformly distributed pores of small diameters much less than the wavelength of incident light. Despite the high porosity, MDR modes are observed in the photoluminescence spectrum of a single sphere. As inclusion of pores may produce significant changes in the refractive index (RI) of the resonator, and as the quality and density of the modes depend on the RI of the resonator, it is important to have a procedure to determine the RI of the resonator as well as to characterize the MDR modes. An iterative procedure that is quite general is presented for mode identification and for the determination of the porosity-induced reduction in the RI and for ascertaining the presence of chromatic dispersion. The presence of high surface area as well as of MDR modes of reasonably high Q-factor makes these particles promising for photo electrochemical applications.
Impact of a surface TiO2 atomic sheet on the electronic transport properties of LaAlO3/SrTiO3 heterointerfaces
Authors: Ohsawa Takeo , Saito Mitsuhiro , Shimizu Ryota , Iwaya Katsuya , Shiraki Susumu , Ikuhara Yuichi , Hitosugi Taro
Published: October 2018

Here, we report the impact of a surface TiO2 atomic sheet on the electronic transport properties of LaAlO3/SrTiO3 heterointerfaces. We demonstrate that when a LaAlO3 film is deposited on a reconstructed SrTiO3(001)-(13×13)-R33.7° substrate, the critical thickness of the LaAlO3 film for emergence of high-mobility electrons is two unit cells. In addition, we observe that as a result of surface passivation by the TiO2 atomic sheet, an electron density of 2.0 × 1014 cm−2 is maintained at the interface owing to the suppression of electron transfer to the surface. A combination of scanning transmission electron microscopy and photoemission spectroscopy reveals that the TiO2 sheet on LaAlO3 plays a key role in determining the conducting properties. This study demonstrates the importance of surface terminations to the electronic structures of buried interfaces.
Machine learning enhanced global optimization by clustering local environments to enable bundled atomic energies
Authors: Meldgaard Søren A. , Kolsbjerg Esben L. , Hammer Bjørk
Published: October 2018

We show how to speed up global optimization of molecular structures using machine learning methods. To represent the molecular structures, we introduce the auto-bag feature vector that combines (i) a local feature vector for each atom, (ii) an unsupervised clustering of such feature vectors for many atoms across several structures, and (iii) a count for a given structure of how many times each cluster is represented. During subsequent global optimization searches, accumulated structure-energy relations of relaxed structural candidates are used to assign local energies to each atom using supervised learning. Specifically, the local energies follow from assigning energies to each cluster of local feature vectors and demanding the sum of local energies to amount to the structural energies in the least squares sense. The usefulness of the method is demonstrated in basin hopping searches for 19-atom structures described by single- or double-well Lennard-Jones type potentials and for 24-atom carbon structures described by density functional theory. In all cases, utilizing the local energy information derived on-the-fly enhances the rate at which the global minimum energy structure is found.
Blind prediction of protein B-factor and flexibility
Authors: Bramer David , Wei Guo-Wei
Published: October 2018

The Debye-Waller factor, a measure of X-ray attenuation, can be experimentally observed in protein X-ray crystallography. Previous theoretical models have made strong inroads in the analysis of beta (B)-factors by linearly fitting protein B-factors from experimental data. However, the blind prediction of B-factors for unknown proteins is an unsolved problem. This work integrates machine learning and advanced graph theory, namely, multiscale weighted colored graphs (MWCGs), to blindly predict B-factors of unknown proteins. MWCGs are local features that measure the intrinsic flexibility due to a protein structure. Global features that connect the B-factors of different proteins, e.g., the resolution of X-ray crystallography, are introduced to enable the cross-protein B-factor predictions. Several machine learning approaches, including ensemble methods and deep learning, are considered in the present work. The proposed method is validated with hundreds of thousands of experimental B-factors. Extensive numerical results indicate that the blind B-factor predictions obtained from the present method are more accurate than the least squares fittings using traditional methods.