bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis, DNA and BSA binding, in vitro anti-proliferative and in vivo anti-angiogenic properties of some cobalt(iii) Schiff base complexes
Authors: Manojkumar Yesaiyan , Ambika Subramanian , Arulkumar Rasu , Gowdhami Balakrishnan , Balaji Perumalsamy , Vignesh Gobalsamy , Arunachalam Sankaralingam , Venuvanalingam Ponnambalam , Thirumurugan Ramaswamy , Akbarsha Mohammad Abdulkader
Published: June 2019

In the recent times metal complexes with dual mechanisms of action, anti-cancer and anti-angiogenic, have gained substantial interest in the field of medicinal chemistry.
A fully reduced {VIV18O42} host and VO43−, Cl− as guest anions: synthesis, characterization and proton conductivity
Authors: Mulkapuri Sateesh , Kurapati Sathish Kumar , Mukhopadhyay Subhabrata , Das Samar K.
Published: June 2019

Two polyoxovanadate compounds, [Na7(H2O)14][H8VIV18O42(VVO4)]·N2H4·7H2O and [Na5(H2O)16][H8VIV18O42(Cl)]·4N2H4·6H2O, each having fully reduced host cage and accommodating eight acidic protons per formula unit, exhibit moderate proton conductivity.
Ammonium hexadeca-oxo-heptavanadate microsquares. A new member in the family of the V7O16 mixed-valence nanostructures
Authors: Navas Daniel , Donoso José Pedro , Magon Claudio , Sotomayor-Torres Clivia M. , Moreno Mabel , Lozano Harold , Benavente Eglantina , González Guillermo
Published: June 2019

This paper presents the new mixed valence heptavanadate (NH4)2V7O16 micro squares, a further but carbonless member of the vanadium oxide nanotubes and nanourchins family, where ammonium ions replace the long carbon chain amines.
A tetraphenylporphyrin/WO3/exfoliated graphite nanocomposite for the photocatalytic degradation of an acid dye under visible light irradiation
Authors: Malefane Mope Edwin , Feleni Usisipho , Kuvarega Alex Tawanda
Published: June 2019

Charge carrier separation in visible light photocatalytic degradation of a dye was achieved by the fabrication of a tetraphenylporphyrin/WO3/exfoliated graphite nanocomposite.
Interface charge-transfer induced intralayer excited-state biexcitons in graphene/WS2 van der Waals heterostructures
Authors: Li Yang , Stolte Nore , Li Baikui , Li Hui , Cheng Guanghui , Pan Ding , Wang Jiannong
Published: June 2019

Highly stable excited-state biexcitons are found in graphene/WS2/BN heterostructures, which is attributed to the charge transfer and exciton dissociation at the hetero-interface.
Structures and biological activities of cycloheptamycins A and B
Authors: Qian Zhengyi , Antosch Janine , Wiese Jutta , Imhoff Johannes F. , Fiedler Hans-Peter , Pöthig Alexander , Gulder Tobias A. M.
Published: June 2019

The structures, absolute configurations and biological activities, particularly against P. acnes, of the cycloheptamycin family of cycloheptadepsipeptides are presented.
Recent advances in the polymerization of elemental sulphur, inverse vulcanization and methods to obtain functional Chalcogenide Hybrid Inorganic/Organic Polymers (CHIPs)
Authors: Zhang Yueyan , Glass Richard S. , Char Kookheon , Pyun Jeffrey
Published: June 2019

Recent developments in the polymerization of elemental sulfur, inverse vulcanization and functional Chalcogenide Hybrid Inorganic/Organic Polymers (CHIPs) are reviewed.
A smart fluorescent biosensor for the highly sensitive detection of BRCA1 based on a 3D DNA walker and ESDR cascade amplification
Authors: Ma Hongmin , Guo Bin , Yan Xiaoyu , Wang Tong , Que Haiying , Gan Xiufeng , Liu Ping , Yan Yurong
Published: June 2019

Nucleic acid analysis plays an important role in the diagnosis of diseases.
Selective coordination of three transition metal ions within a coiled-coil peptide scaffold
Authors: Boyle Aimee L. , Rabe Martin , Crone Niek S. A. , Rhys Guto G. , Soler Nicolas , Voskamp Patrick , Pannu Navraj S. , Kros Alexander
Published: June 2019

Three peptide chains selectively coordinate specific transition metal ions, triggering folding and the formation of a novel metallopeptide complex.
A switchable iron-based coordination polymer toward reversible acetonitrile electro-optical readout
Authors: Resines-Urien Esther , Burzurí Enrique , Fernandez-Bartolome Estefania , García García-Tuñón Miguel Ángel , de la Presa Patricia , Poloni Roberta , Teat Simon J. , Costa Jose Sanchez
Published: June 2019

A novel non-porous molecular-based acetonitrile sensor is reported. This material shows a reversible magneto-structural transition under desorption/absorption of acetonitrile involving a drastic switch in its optical and electronic properties.
Preparation, characterization and properties of intrinsic self-healing elastomers
Authors: Wang Zhanhua , Lu Xili , Sun Shaojie , Yu Changjiang , Xia Hesheng
Published: June 2019

Recent progress in preparation, characterization and properties of different kinds of intrinsic self-healing elastomers is summarized in this review article.
MicroRNA-221 promotes cisplatin resistance in osteosarcoma cells by targeting PPP2R2A
Authors: Yu Wen-chao , Chen Hui-hao , Qu Yan-yan , Xu Chun-wei , Yang Chen , Liu Yan
Published: June 2019

Osteosarcoma (OS), the most common malignant bone tumor, is the main cause of cancer-related deaths in children and young adults. Despite the combination of surgery and multi-agent chemotherapy, patients with OS who develop resistance to chemotherapy or experience recurrence have a dismal prognosis. MicroRNAs (miRNAs) are a class of small noncoding RNAs that repress their targets by binding to the 3′-UTR and/or coding sequences, leading to the inhibition of gene expression. miR-221 is found to be up-regulated in tumors when compared with their matched normal osteoblast tissues. We also observed significant miR-221 up-regulation in the OS cell lines, MG-63, SaoS-2, and U2OS, when compared with the normal osteoblast cell line, HOb. Overexpression of miR-221 promoted OS cell invasion, migration, proliferation, and cisplatin resistance. MG-63 and SaoS-2 cells transfected with miR-221 mimics were more resistant to cisplatin. The IC50 of MG-63 cells transfected with control mimics was 1.24 μM. However, the IC50 of MG-63 cells overexpressing miR-221 increased to 7.65 μM. Similar results were found in SaoS-2 cells, where the IC50 for cisplatin increased from 3.65 to 8.73 μM. Thus, we report that miR-221 directly targets PP2A subunit B (PPP2R2A) in OS by binding to the 3′-UTR of the PPP2R2A mRNA. Restoration of PPP2R2A in miR-221-overexpressing OS cells recovers the cisplatin sensitivity of OS cells. Therefore, the present study suggests a new therapeutic approach by inhibiting miR-221 for anti-chemoresistance in OS.
Identification and characterization of a new sulfoacetaldehyde reductase from the human gut bacterium Bifidobacterium kashiwanohense
Authors: Zhou Yan , Wei Yifeng , Nanjaraj Urs Ankanahalli N. , Lin Lianyun , Xu Tong , Hu Yiling , Ang Ee Lui , Zhao Huimin , Yuchi Zhiguang , Zhang Yan
Published: June 2019

Hydroxyethylsulfonate (isethionate (Ise)) present in mammalian tissues is thought to be derived from aminoethylsulfonate (taurine), as a byproduct of taurine nitrogen assimilation by certain anaerobic bacteria inhabiting the taurine-rich mammalian gut. In previously studied pathways occurring in environmental bacteria, isethionate is generated by the enzyme sulfoacetaldehyde reductase IsfD, belonging to the short-chain dehydrogenase/reductase (SDR) family. An unrelated sulfoacetaldehyde reductase SarD, belonging to the metal-dependent alcohol dehydrogenase superfamily (M-ADH), was recently discovered in the human gut sulfite-reducing bacterium Bilophila wadsworthia (BwSarD). Here we report the structural and biochemical characterization of a sulfoacetaldehyde reductase from the human gut fermenting bacterium Bifidobacterium kashiwanohense (BkTauF). BkTauF belongs to the M-ADH family, but is distantly related to BwSarD (28% sequence identity). The crystal structures of BkTauF in the apo form and in a binary complex with NAD+ were determined at 1.9 and 3.0 Å resolution, respectively. Mutagenesis studies were carried out to investigate the involvement of active site residues in binding the sulfonate substrate. Our studies demonstrate the presence of sulfoacetaldehyde reductase in Bifidobacteria, with a possible role in isethionate production as a byproduct of taurine nitrogen assimilation.
Investigation of the unbalanced magnetic pull damping effect in squirrel cage induction machines
Authors: Chuan Hawwooi , Shek Jonathan K. H.
Published: June 2019

The unbalanced magnetic pull (UMP) in electrical machines is due to the existence of additional magnetic flux waves. When squirrel cage induction machine (SCIM) running below its rated slip, most of the additional magnetic flux waves can be damped by the counteracting flux waves produced by its parallel‐connected rotor bars. Here, this UMP damping effect is comprehensively discussed by comparing the UMP and the air‐gap flux of SCIMs and wound rotor induction machines. Subsequently, a UMP damping coefficient is proposed to be included in the conventional UMP analytical model, in which the damping of UMP caused by the counteracting flux waves can be taken into account. Lastly, the UMP of SCIM at different excitation frequencies and rotor resistance are investigated to further verify the UMP damping effect.
Model predictive current control of DSTATCOM with simplified weighting factor selection using VIKOR method for power quality improvement
Authors: Kumar Alladi Pranay , Kumar Ganjikunta Siva , Sreenivasarao Dharmavarapu , Myneni Hareesh
Published: June 2019

In this study, model predictive control (MPC) of the three‐phase split capacitor (TPSC) distribution static compensator (DSTATCOM) using VlseKriterijumska Optimizacija I Kompromisno Resenje (VIKOR) method is proposed. Power quality improvement using MPC involves the selection of switching state which minimises the difference between reference and actual DSTATCOM currents. However, the limitation of MPC is higher switching frequency and limitation of TPSC DSTATCOM is voltage divergence of dc‐link capacitors. To alleviate these problems, one constraint is to suppress the voltage divergence and the other is to reduce the switching frequency is included in the cost function using weighting factors. Optimal selection of switching state for minimisation of a multi‐constraint cost function is depending on the weighting factor; however, its tuning is a challenging task. In this study, the simplification of weighting factor tuning is achieved using the VIKOR method and it further selects the optimal switching state based on a specific measure of closeness to the ideal solution and multi‐criteria ranking index. The advantages of the proposed work are compensation of power quality issues, balance the dc‐link voltages, switching frequency reduction of inverter and simplification of weighting factor tuning. Finally, the proposed work is evaluated using simulation and experimental studies.
Interline dc power flow controller with fault current‐limiting capability
Authors: Li Guoqing , Bian Jing , Wang He , Wang Zhenhao , Xin Yechun , Guan Jiaxin
Published: June 2019

Power flow control and fault current limitation are two major problems that require an urgent solution in a direct current (dc) grid. This study proposes a novel interline dc power flow controller having a fault current limitation capability (FCL–PFC). The proposed controller is expected to realise overall control of the internal power flow in a dc grid and to limit the fault current under fault conditions. FCL–PFC exhibits small capacity and low loss and does not require energy from an alternating current (ac) system. The topological structure of FCL–PFC is first introduced. Then, the principles of power flow control and self‐power balance using the dc voltage and ac circulating current, respectively, is discussed. The control strategy under stable conditions is further designed. Based on the proposed FCL–PFC action sequence under fault conditions, this study describes the calculation and analysis of the dc fault current in different periods for maximising the fault current limitation ability of FCL–PFC. Finally, a simulation model is used in PSCAD/EMTDC to verify the power flow control and fault current limitation capabilities of the proposed FCL–PFC. The economy of combining FCL–PFC with direct current circuit breakers is analysed.
Investigations of the instantaneous performance of a solar chimney power plant installed in Aswan using IoT
Authors: Fathy Cidek Esmail Mohamed , Mekhail Tarek
Published: June 2019

Although solar chimney power plant (SCPP) has a promising potential to convert the solar energy to electric power, greater efforts are needed to ensure its successful commercialisation on a large scale. The main obstacles with regard to the large‐scale applications of SCPP are its efficiency, bulk size and dependency on solar irradiation. A comprehensive study on the integration of the Internet‐of‐Things (IoT) as a novel technique to monitor and hence improve its performance is presented. A small‐scale SCPP is designed and constructed specifically for this purpose in Aswan, Egypt. The instantaneous performance parameters (temperature, solar intensity, wind speed, open circuit voltage, power etc.) were measured and further processed using IoT. The results show that IoT has a promising potential to enhance the performance of the system by providing a complete picture of the whole measurements. This is considered as a step forward for enhancing the technologies which will ensure the success of large‐scale SCPP in the real world.
The correct estimate of the probability of false detection of the matched filter in weak-signal detection problems
Authors: Vio R. , Andreani P. , Biggs A. , Hayatsu N.
Published: June 2019

The matched filter (MF) represents one of the main tools to detect signals from known sources embedded in the noise. In the Gaussian isotropic case, the noise can be assumed to be the realization of a Gaussian random field (GRF). The most important property of the MF, the maximization of the probability of detection subject to a constant probability of false detection or false alarm (PFA), makes it one of the most popular techniques. However, the MF technique relies upon the a priori knowledge of the number and the position of the searched signals in the GRF (e.g. an emission line in a spectrum or a point-source on a map), which usually are not available. A typical way out is to assume that, if present, the position of a signal coincides with one of the peaks in the matched filtered data. A detection is claimed when the probability that a given peak is due only to the noise (i.e. the PFA) is smaller than a prefixed threshold. This last step represents a critical point in the detection procedure. Since a signal is searched for amongst the peaks, the probability density function (PDF) of the amplitudes of the latter has to be used for the computation of the PFA. Such a PDF, however, is different from the Gaussian. Moreover, the probability that a detection is false depends on the number of peaks present in the filtered GRF. This is because the greater the number of peaks in a GRF, the higher the probability of peaks due to the noise that exceed the detection threshold. If this fact is not taken into account, the PFA can be severely underestimated. In statistics this is a well-known problem named the multiple comparisons, multiple testing, or multiple hypotheses problem, whereas in other fields it is known as the look-elsewhere effect. Many solutions have been proposed to this problem. However, most of them are of a non-parametric type hence not able to exploit all the available information. Recently, this limitation has been overcome by means of two efficient parametric approaches. One is explicitly based on the PDF of the peak amplitudes of a smooth and isotropic GRF whereas the other makes use of the Gumbel distribution, which represents the asymptotic PDF of the corresponding extreme. On the basis of numerical experiments as well of an application to an interferometric map obtained with the Atacama Large Millimeter/submillimeter Array (ALMA), we show that, although the two methods produce almost identical results, the first is more flexible and at the same time allows us to check the reliability of the detection procedure.
Variability of young stellar objects in the star-forming region Pelican Nebula
Authors: Bhardwaj A. , Panwar N. , Herczeg G. J. , Chen W. P. , Singh H. P.
Published: June 2019

Context. Pre-main-sequence variability characteristics can be used to probe the physical processes leading to the formation and initial evolution of both stars and planets.

Aims. The photometric variability of pre-main-sequence stars is studied at optical wavelengths to explore star–disk interactions, accretion, spots, and other physical mechanisms associated with young stellar objects.

Methods. We observed a field of 16′ × 16′ in the star-forming region Pelican Nebula (IC 5070) at BVRI wavelengths for 90 nights spread over one year in 2012−2013. More than 250 epochs in the VRI bands are used to identify and classify variables up to V ∼ 21 mag. Their physical association with the cluster IC 5070 is established based on the parallaxes and proper motions from the Gaia second data release (DR2). Multiwavelength photometric data are used to estimate physical parameters based on the isochrone fitting and spectral energy distributions.

Results. We present a catalog of optical time-series photometry with periods, mean magnitudes, and classifications for 95 variable stars including 67 pre-main-sequence variables towards star-forming region IC 5070. The pre-main-sequence variables are further classified as candidate classical T Tauri and weak-line T Tauri stars based on their light curve variations and the locations on the color-color and color-magnitude diagrams using optical and infrared data together with Gaia DR2 astrometry. Classical T Tauri stars display variability amplitudes up to three times the maximum fluctuation in disk-free weak-line T Tauri stars, which show strong periodic variations. Short-term variability is missed in our photometry within single nights. Several classical T Tauri stars display long-lasting (≥10 days) single or multiple fading and brightening events of up to two magnitudes at optical wavelengths. The typical mass and age of the pre-main-sequence variables from the isochrone fitting and spectral energy distributions are estimated to be ≤1 M⊙ and ∼2 Myr, respectively. We do not find any correlation between the optical amplitudes or periods with the physical parameters (mass and age) of pre-main-sequence stars.

Conclusions. The low-mass pre-main-sequence stars in the Pelican Nebula region display distinct variability and color trends and nearly 30% of the variables exhibit strong periodic signatures attributed to cold spot modulations. In the case of accretion bursts and extinction events, the average amplitudes are larger than one magnitude at optical wavelengths. These optical magnitude fluctuations are stable on a timescale of one year.
The complex chemistry of hot cores in Sgr B2(N): influence of cosmic-ray ionization and thermal history
Authors: Bonfand M. , Belloche A. , Garrod R. T. , Menten K. M. , Willis E. , Stéphan G. , Müller H. S. P.
Published: June 2019

Context. As the number of complex organic molecules (COMs) detected in the interstellar medium increases, it becomes even more important to place meaningful constraints on the origins and formation pathways of such chemical species. The molecular cloud Sagittarius B2(N) is host to several hot molecular cores in the early stage of star formation, where a great variety of COMs are detected in the gas phase. Given its exposure to the extreme conditions of the Galactic center (GC) region, Sgr B2(N) is one of the best targets to study the impact of environmental conditions on the production of COMs.

Aims. Our main goal is to characterize the physico-chemical evolution of Sgr B2(N)’s sources in order to explain their chemical differences and constrain their environmental conditions.

Methods. The chemical composition of Sgr B2(N)’s hot cores, N2, N3, N4, and N5 is derived by modeling their 3 mm emission spectra extracted from the Exploring Molecular Complexity with ALMA (EMoCA) imaging spectral line survey performed with the Atacama Large Millimeter/submillimeter Array (ALMA). We derived the density distribution in the envelope of the sources based on the masses computed from the ALMA dust continuum emission maps. We used the radiative transfer code RADMC-3D to compute temperature profiles and inferred the current luminosity of the sources based on the COM rotational temperatures derived from population diagrams. We used published results of 3D radiation-magnetohydrodynamical (RMHD) simulations of high-mass star formation to estimate the time evolution of the source properties. We employed the astrochemical code MAGICKAL to compute time-dependent chemical abundances in the sources and to investigate how physical properties and environmental conditions influence the production of COMs.

Results. The analysis of the abundances of 11 COMs detected toward Sgr B2(N2-N5) reveals that N3 and N5 share a similar chemical composition while N2 differs significantly from the other sources. We estimate the current luminosities of N2, N3, N4, and N5 to be 2.6 × 105 L⊙, 4.5 × 104 L⊙, 3.9 × 105 L⊙, and 2.8 × 105 L⊙, respectively. We find that astrochemical models with a cosmic-ray ionization rate of 7 × 10−16 s−1 best reproduce the abundances with respect to methanol of ten COMs observed toward Sgr B2(N2-N5). We also show that COMs still form efficiently on dust grains with minimum dust temperatures in the prestellar phase as high as 15 K, but that minimum temperatures higher than 25 K are excluded.

Conclusions. The chemical evolution of Sgr B2(N2-N5) strongly depends on their physical history. A more realistic description of the hot cores’ physical evolution requires a more rigorous treatment with RMHD simulations tailored to each hot core.
Retour d’expérience sur la traitabilité d’une nitrosamine en production d’eau potable à l’échelle pilote
Authors: Helmer C. , Neveu A. , Hauchard V. , Hassanzadeh S. , Danel O.
Published: June 2019

La présence de N-nitrosomorpholine (N-MOR) et de son précurseur, la morpholine (MOR), a été détectée en 2012 dans le forage d’Yport, l’une des principales ressources d’eau brute du Havre Seine Métropole. La valeur en N-MOR a ponctuellement dépassé le seuil de 100 ng/L recommandé pour l’eau distribuée par la direction générale de la santé. Dans ce contexte, la collectivité a sollicité une étude visant définir la filière de traitement cible adaptée à l’élimination de ces micropolluants émergents. Le souhait de la collectivité étant de privilégier des solutions de traitement retirant les micropolluants plutôt que celles les transformant, l’étude a évalué les performances des procédés d’adsorption sur charbon actif et d’osmose inverse basse pression (OIBP), séparément et en couplage. Deux types de charbon et trois types de membranes ont été testés. Les essais pilotes menés sur site ont montré que la mise en œuvre de charbon actif en poudre (CAP) au sein d’un réacteur spécifique permet une élimination acceptable de la N-MOR (60  % max) à condition de mettre en œuvre un taux de traitement élevé (› 25 g/m3) et un temps de contact limité (10 h max.) pour éviter les phénomènes de désorption. L’élimination de la MOR par le CAP est quant à elle très limitée (10  % max). Les essais pilotes sur membranes d’OIBP (seuil de coupure ‹ 200 Da) ont mis en avant une élimination élevée (environ 90  %) de la N-MOR et plus limitée de la MOR de 15 à 85  % selon les membranes testées. Transposer les résultats obtenus de l’échelle pilote à l’échelle industrielle est possible pour la filtration membranaire, mais plus difficile pour le réacteur CAP, du fait qu’il n’existe pas à ce jour de technologies adaptées aux conditions optimales définies (taux élevé, âge des boues de CAP faible).
X-linked Charcot–Marie–Tooth Disease Presenting with Stuttering Stroke-like Symptoms
Authors: Hardy Duriel I. , Licht Daniel J. , Vossough Arastoo , Kirschen Matthew P.
Published: June 2019

X-linked Charcot–Marie–Tooth disease (CMTX1) is the second most common form of Charcot–Marie–Tooth disease (CMT). It is caused by a mutation in the gap junction β 1 (GJB1) gene, which encodes for connexin-32. In addition to the peripheral neuropathy and foot deformities observed in classic CMT, central nervous system symptoms and magnetic resonance imaging (MRI) signal abnormalities in the brain have been reported in patients with CMTX1. Here we describe two cases of adolescent males who presented with stuttering neurologic deficits that were initially suggestive of acute ischemic stroke and were ultimately diagnosed with genetically confirmed CMTX1. Both patients had evidence of T2 hyperintensity and decreased diffusion on MRI in the centrum semiovale, posterior corona radiata, posterior periventricular white matter, and corpus callosum. Though rare, these cases illustrate the importance of comprehensive neurologic history, physical examination, and appropriate diagnostic evaluation.
Optimal configuration of distributed heat source to promote the wind power penetration in combined heat and power system
Authors: Yi Zhongkai , Xu Yinliang , Li Zhimin
Published: June 2019

With increasing heating demand and installed capacity of wind farms, combined heat and power (CHP) systems with inflexible generation are confronted with a major challenge for the efficient utilization of the wind power. Distributed heat sources (DHSs), such as electric boilers and heat storage, offer an effective way to enhance wind power penetration in a combined heat and power system by reducing the electric-heat coupling of the CHP unit. In this paper, an assessment approach for the wind power penetration of a CHP system with DHSs is proposed, and a two-stage multiple types of DHSs optimal configuration strategy to realize the minimum construction cost at a certain permissible wind power curtailment rate is established. After that, the proposed strategy is applied to a case study of a practical CHP system with in-depth analysis and detailed discussion, which reveals the effectiveness of the proposed strategy and indicates its promising applications for DHS configuration.
Ultrafast carrier recombination in highly n-doped Ge-on-Si films
Authors: Allerbeck J. , Herbst A. J. , Yamamoto Y. , Capellini G. , Virgilio M. , Brida D.
Published: June 2019

We study the femtosecond carrier dynamics of n-type doped and biaxially strained Ge-on-Si films which occurs upon impulsive photoexcitation by means of broadband near-IR transient absorption spectroscopy. The modeling of the experimental data takes into account the static donor density in a modified rate equation for the description of the temporal recombination dynamics. The measurements confirm the negligible contribution at a high n-type doping concentration, in the 1019 cm−3 range, of Auger processes as compared to defect-related Shockley-Read-Hall recombination. Energy resolved dynamics reveal further insights into the doping-related band structure changes and suggest a reshaping of direct and indirect conduction band valleys to a single effective valley along with a significant spectral broadening of the optical transitions.
Temnothorax albipennis migration inspired semi-flocking control for mobile sensor networks
Authors: Yuan Wanmai , Ganganath Nuwan , Cheng Chi-Tsun , Guo Qing , Lau Francis C. M.
Published: June 2019

Mobile sensor networks (MSNs) are utilized in many sensing applications that require both target seeking and tracking capabilities. Dynamics of mobile agents and the interactions among them introduce new challenges in designing robust cooperative control mechanisms. In this paper, a distributed semiflocking algorithm inspired by Temnothorax albipennis migration model is proposed to address the above issues. Mobile agents under the control of the proposed semiflocking algorithm are capable of detecting targets faster and tracking them with lower energy consumption when compared with existing MSN motion control algorithms. Furthermore, the proposed semiflocking algorithm can operate energy-efficiently on both flat and uneven terrains. Simulation results demonstrate that the proposed semiflocking algorithm can provide promising performances in target seeking and tracking applications of MSNs.
Optical and electrical characteristics of carbonized film prepared from coal tar pitch under a high magnetic field of 10 T
Authors: Hamasaki Atom , Fujio Kazuki , Mori Tomoya , Iide Masashi , Takeuchi Yuka , Katsuki Akio , Ozeki Sumio
Published: June 2019

Carbon microcrystallites can become oriented in the carbonization process of coal tar pitch, which occurs with the characteristic where a mesophase is obtained, by using a magnetic field. An oriented film that has the ability to transmit visible light from 450 to 800 nm can be obtained by sandwiching an appropriate amount of coal pitch between two glass plates and heating in an inert atmosphere at 793 K under a magnetic field. This film can be used to obtain the same linearly polarized light as a commercially available polarizing element. The degree of orientation of the film prepared in a magnetic field of 3 T is not sufficient to use as a polarizer, but a magnetic field of 6 T is able to sufficiently suppress the passage of crossed polarized light. The electrical conductivity of the carbon film prepared at 793 K is improved by 10 times by the application of a magnetic field of 10 T. The electrical conductivity is sensitive to the magnetic field, and there is a possibility that it can be further improved by applying 10 T or more. Coal tar pitch is the residue after obtaining coke from coal, and the optical and electrical advantage of a material prepared in the magnetic field derived from such natural products is clarified.
Influence of HfO2 interlayers on magnetocrystalline anisotropy in Fe|MgO|Fe magnetic tunnel junction: First-principles investigation
Authors: Chen W. Z. , Zhang J. , Yang B. S. , Jiang L. N. , Yu T. , Han X. F.
Published: June 2019

Perpendicular magnetic anisotropy (PMA) is important for MgO based magnetic tunnel junction and magnetic random access memory to be integrated on a large scale due to high thermal stability and low critical switching current. Here, we applied the density functional theory to study the effect of HfO2 inserting layers on PMA of Fe|MgO|Fe tunnel junction. It was found that the magnetocrystalline anisotropy (MCA) of the junction for 5 layers Fe electrode was up to 1.95 mJ/m2 with one unit cell HfO2 interlayer, while it was 1.72 mJ/m2 without the interlayer. More importantly, analyzed by the layer and orbital-resolved MCA based on the second-order perturbation theory, MCA characters and the underlying mechanism of PMA become very different after inserting HfO2. The remarkable difference is the MCA contribution of the second interfacial Fe layers, which is about 0.4 mJ/m2 for Fe|MgO|Fe junctions, while it was larger than 0.7 mJ/m2 for Fe|HfO2|MgO|HfO2|Fe junctions. Furthermore, Fe-dz2 and O-pz hybridization plays a crucial role in MCA contribution from the first interfacial Fe layers since the interfacial Fe–O bond length reduces from 2.20 Å to 1.77 Å with inserting HfO2 layers. Besides, the reduction in Fe–O bond length can redistribute the orbital-resolved electrons of the second and third closest Fe layer to the interface to enhance their absolute values of MCA contributions, which results in the strong dependence of MCA on Fe thickness.
Multistability driven by inhibitory kinetics in a discrete-time size-structured chemostat model
Authors: Zhang Dan , Wang Lin
Published: June 2019

In this paper, we consider a discrete size-structured nonlinear chemostat model with inhibitory kinetics and multiple competing species. We show that, same as in models with monotone increasing nutrient uptake response functionals studied in the literature, one essential growth-limiting nutrient can support at most one species. More interestingly, we show that, differing from monotone increasing kinetics, inhibitory kinetics can induce several types of multistability and the competitive outcome is initial condition dependent. The species with the smallest lower break-even value is not always the winning species, and the winning species can exhibit sustained periodic oscillations and even chaotic irregular oscillations.
Synchronization behavior in a ternary phase model
Authors: DeTal N. , Taheri H. , Wiesenfeld K.
Published: June 2019

Localized traveling-wave solutions to a nonlinear Schrödinger equation were recently shown to be a consequence of Fourier mode synchronization. The reduced dynamics describing mode interaction take the form of a phase model with novel ternary coupling. We analyze this model in the presence of quenched disorder and explore transitions to partial and complete synchronization. For both Gaussian and uniform disorder, first-order transitions with hysteresis are observed. These results are compared with the phenomenology of the Kuramoto model which exhibits starkly different behavior. An infinite-oscillator limit of the model is derived and solved to provide theoretical predictions for the observed transitions. Treatment of the nonlocal ternary coupling in this limit sheds some light on the model’s novel structure.
Quantum master equation approach to singlet fission dynamics in pentacene ring-shaped aggregate models
Authors: Nakano Masayoshi
Published: June 2019

The quantum master equation approach is applied to the singlet fission (SF) dynamics of pentacene ring-shaped aggregate models to clarify the Frenkel excitonic (FE) coupling effects on the SF rate and correlated-triplet pair (TT) yield as well as their dependences on the aggregate structure and size. Interestingly, the smallest ring model, a ring-shaped trimer, is found to exhibit a significantly smaller SF rate and a slightly smaller TT yield than those of the dimer model with the same intermonomer interaction and to show remarkable variations in the SF dynamics with increasing the FE coupling. With increasing the size of the aggregates with FE coupling, it is found that the SF rate rapidly increases, attains the maximum at 17-mer (∼3 times enhancement compared to the non-FE-coupling case), and then decreases, approaching a stationary value around 25-mer, while the almost stationary TT yield at 25-mer remains 16% smaller than that in the non-FE-coupling case. These features are found to be in qualitative agreement with those in the corresponding linear aggregates, although the aggregate size gives a maximum SF rate, and the values of the maximum SF rate as well as of the converged TT yield are different between the ring-shaped and linear aggregates. These results are interpreted based on the relative relaxation factors between the adiabatic exciton states as well as on the vibronic coupling effects. The present results contribute to a deeper understanding of the aggregate structure and size dependences of SF dynamics and to constructing the design guidelines for highly efficient SF aggregates.
A numerical calculation method for the precise prediction analysis of relationship between nanostructure and strain sensitivity
Authors: Zhao Fengyuan , Liu Manxiao , Liu Jize , Fan Dongyang , Yu Yanmei , Lu Qianwen , Tan Yuxiang , Tao Qingchuan , Zhang Xinxing
Published: June 2019

Wearable strain sensors have been attracting increased interest in human motion detection. To meet the demands of complex realistic situations, directed elaborate nanostructure design is indispensable. However, the lack of an efficient numerical calculation method for the prediction and analysis of resistance-strain response behavior greatly restricts sensors’ applications. In this work, a numerical calculation method based on Breadth-First Searching of nanostructured Conductive Network Paths (BFS-CNP) is demonstrated to precisely analyze the relationship between nanostructure and strain sensitivity. The multilayer-segregated structure was applied to illustrate how the numerical system works in the analysis of structure design and prediction of sensing performance. Strain sensors with different strain-sensing performances are developed under the guidance of the numerical calculation method for different applications, such as grasping and pronunciations. This work gives valuable guidance for the numerical analysis of nanostructures and provides critical insight into the nanostructure design for flexible strain sensors.
Studying drugs and diseases with “body-on-a-chip” models
Authors: Patrick Chris
Published: June 2019

Authors summarize mathematical modeling strategies used to design and analyze multi-organ microphysiological systems.
Transcriptomic profiling revealed genes involved in response to cold stress in maize
Authors: Li Meng , Sui Na , Lin Lin , Yang Zhen , Zhang Yuanhu
Published: June 2019

Maize is an important food crop. Chilling stress can decrease maize production by affecting seed germination and seedling growth, especially in early spring. We analysed chlorophyll fluorescence, membrane lipids, secondary metabolites and the transcriptome of two maize inbred lines (chilling-tolerant M54 and chilling-sensitive 753F) after 0, 4 and 24 h cold stress. M54 showed better ability to protect PSII and accumulate secondary metabolites. From RNA sequencing data, we determined that the majority of cold-affected genes were involved in photosynthesis, secondary metabolism, and signal transduction. Genes important for maintaining photosystem structure and for regulating electron transport were less affected by cold stress in M54 than in 753F. Expression of genes related to secondary metabolism and unsaturated fatty acid synthesis were upregulated more strongly in M54 than in 753F and M54 accumulated more unsaturated fatty acids and secondary metabolites. As a result, M54 achieved relatively high cold tolerance by protecting the photosystems and maintaining the stability of cell membranes.
Two years of impairment: plastic packing strap on a bull shark (Carcharhinus leucas) in Fiji
Authors: Brunnschweiler Juerg M. , Marosi Natasha D.
Published: June 2019

Plastic straps have been recorded from single point in time observations in various shark species. Here, we report a bull shark with a plastic strap around its head from the time of acquisition until its loss after two years.
Widespread B cell perturbations in HIV-1 infection afflict naive and marginal zone B cells
Authors: Liechti Thomas , Kadelka Claus , Braun Dominique L. , Kuster Herbert , Böni Jürg , Robbiani Melissa , Günthard Huldrych F. , Trkola Alexandra
Published: June 2019

Perturbations in B cells are a hallmark of HIV-1 infection. This is signified by increased numbers of exhausted CD21neg memory B cells, driven by continuous antigen-specific and bystander activation. Using high-dimensional flow cytometry, we demonstrate that this exhausted phenotype is also prevalent among peripheral antigen-inexperienced naive and marginal zone (MZ) B cells in acute and chronic HIV-1 infection. A substantial fraction of naive and MZ B cells exhibit down-regulated CD21 levels and diminished response to B cell receptor (BCR)–dependent stimulation. Compared with CD21pos subsets, the CD21neg naive and MZ B cells differ in the expression of chemokine receptors and activation markers. Effective antiretroviral treatment normalizes peripheral naive and MZ B cell populations. Our results emphasize a more widely spread impairment of B cells in HIV-1 infection than previously appreciated, including antigen-inexperienced cells. This highlights the importance of monitoring functional capacities of naive B cells in HIV-1 infection, as exhausted CD21neg naive B cells may severely impair induction of novel B cell responses.
Operational range of a ferrofluid pocket bearing
Authors: Boots A S T , Spronck J W , van Ostayen R A J , Lampaert S G E
Published: June 2019

Ferrofluid pocket bearings are interesting for fast and precise positioning systems thank to the absence of stick-slip, the low viscous friction and their cost-effective nature. However, the characteristics of the bearing change due to over(de)compression since air escapes out of the enclosed pocket. This article presents an experimentally validated model that includes the air mass inside the pocket in the calculation of the equilibrium position of the ferrofluid bearing. Moreover, a simple and efficient way to obtain the operational range of the bearing is presented and a sensitivity analysis was performed. The sensitivity analysis showed that ferrofluid pocket bearings are always self-aligning and that the tilt stiffness increases when the fly height decreases or the tilt angle increases.
Doping dependence of the pinning efficiency in K-doped Ba122 single crystals prior to and after fast neutron irradiation
Authors: Kagerbauer D , Ishida S , Mishev V , Song D , Ogino H , Eisaki H , Nakajima M , Iyo A , Eisterer M
Published: June 2019

A sharp peak was observed in the doping dependence of the critical current density, J
c, in potassium doped Ba122 single crystals. This behavior is in contrast to the doping dependence of the transition temperature, T
c, which varies much more smoothly around its maximum. We performed fast neutron irradiation on the crystals in order to find out whether the J
c peak results from intrinsic properties or the particular defect landscape. Fast neutrons are known to introduce defects up to a size of a few nanometers, which have proven to be more efficient for flux pinning than the crystallographic defects in the pristine crystals. We find that the peak in J
c shifts to higher doping levels after the irradiation, broadens, and roughly follows the shape of the T
c curve. Moreover, a power law between J
c and T
c is observed in the irradiated crystals, which can be explained by relations between fundamental parameters and T
c observed previously in iron-based superconductors. This power law does not hold for the pristine crystals which indicates that the doping dependence of J
c results from an enhanced pinning efficiency in the under-doped area of the phase diagram.
Quantum gradient descent and Newton’s method for constrained polynomial optimization
Authors: Rebentrost Patrick , Schuld Maria , Wossnig Leonard , Petruccione Francesco , Lloyd Seth
Published: June 2019

Optimization problems in disciplines such as machine learning are commonly solved with iterative methods. Gradient descent algorithms find local minima by moving along the direction of steepest descent while Newton’s method takes into account curvature information and thereby often improves convergence. Here, we develop quantum versions of these iterative optimization algorithms and apply them to polynomial optimization with a unit norm constraint. In each step, multiple copies of the current candidate are used to improve the candidate using quantum phase estimation, an adapted quantum state exponentiation scheme, as well as quantum matrix multiplications and inversions. The required operations perform polylogarithmically in the dimension of the solution vector and exponentially in the number of iterations. Therefore, the quantum algorithm can be useful for high-dimensional problems where a small number of iterations is sufficient.
Optimal control for feedback cooling in cavityless levitated optomechanics
Authors: Ferialdi Luca , Setter Ashley , Toroš Marko , Timberlake Chris , Ulbricht Hendrik
Published: June 2019

We consider feedback cooling in a cavityless levitated optomechanics setup, and we investigate the possibility to improve the feedback implementation. We apply optimal control theory to derive the optimal feedback signal both for quadratic (parametric) and linear (electric) feedback. We numerically compare optimal feedback against the typical feedback implementation used for experiments. In order to do so, we implement a state estimation scheme that takes into account the modulation of the laser intensity. We show that such an implementation allows us to increase the feedback strength, leading to faster cooling rates and lower center-of-mass temperatures.
Magnetic phase diagram of the quantum spin chain compound SrCo2V2O8: a single-crystal neutron diffraction study
Authors: Shen L , Zaharko O , Birk J O , Jellyman E , He Z , Blackburn E
Published: June 2019

We explore magnetic order in the quantum spin chain compound SrCo2V2O8 up to 14.9 T and down to 50 mK, using single-crystal neutron diffraction. Upon cooling in zero-field, commensurate antiferromagnetic (C-AFM) order with modulation vector

k

C

 = (0, 0, 1) develops below T
N ≃ 5.0 K. Applying an external magnetic field (H∥c axis) destabilizes this C-AFM order, leading to an order-disorder transition between T
N and ∼1.5 K. Below 1.5 K, a commensurate to incommensurate (IC-AFM) transition occurs at 3.9 T, above which the magnetic reflections can be indexed by

k

IC

 = (0, 0, 1 ± δl). The incommensurability δl scales monotonically with H until the IC-AFM order disappears around 7.0 T. Magnetic reflections modulated by

k

C

emerge again at higher fields. While the characters of the C-AFM, IC-AFM and the emergent AFM order in SrCo2V2O8 appear to fit the descriptions of the Néel, longitudinal spin density wave and transverse AFM order observed in the related compound BaCo2V2O8, our results also reveal several unique signatures that are not present in the latter, highlighting the inadequacy of mean-field theory in addressing the complex magnetic order in systems of this class.
Efficient swap algorithms for molecular dynamics simulations of equilibrium supercooled liquids
Authors: Berthier Ludovic , Flenner Elijah , Fullerton Christopher J , Scalliet Camille , Singh Murari
Published: June 2019

It was recently demonstrated that a simple Monte Carlo (MC) algorithm involving the swap of particle pairs dramatically accelerates the equilibrium sampling of simulated supercooled liquids. We propose two numerical schemes integrating the efficiency of particle swaps into equilibrium molecular dynamics (MD) simulations. We first develop a hybrid MD/MC scheme combining molecular dynamics with the original swap Monte Carlo. We implement this hybrid method in LAMMPS, a software package employed by a large community of users. Secondly, we define a continuous time version of the swap algorithm where both the positions and diameters of the particles evolve via Hamilton’s equations of motion. For both algorithms, we discuss in detail various technical issues as well as the optimisation of simulation parameters. We compare the numerical efficiency of all available swap algorithms and discuss their relative merits.