bluuebunny/crossref_metadata_2025 huggingface dataset:
Selective sensing of a Cu(ii) ion by organotin anchored keto-enamine ligands
Authors: Vinayak Richa , Nayek Hari Pada
Published: September 2019

New organotin carboxylates [{(n-Bu)2Sn(HL)}2O]2 (1), [(t-Bu)2Sn(HL)2] (2) and [Ph3Sn(HL)] (3) have been synthesized and used for sensing of Cu(ii) ion. Complex 3 shows highest binding constant and better limit of detection than other complexes.
Hydrophilic encapsulation of reduced graphite oxide (r-GO) by admicellar polymerization for application in biosensors
Authors: Li Feifei , Wang Luyao , Li Mengmeng , Lei Lin
Published: September 2019

Hydrophilic encapsulation of reduced graphite oxide (r-GO) was achieved by admicellar polymerization.
A benzimidazole-based non-symmetrical tripodal receptor for the ratiometric fluorescence sensing of fluoride ions and solid state recognition of sulfate ions
Authors: Borah Nilotpal , Nayak Biswajit , Gogoi Abhijit , Das Gopal
Published: September 2019

A novel tripodal receptor has been reported as a fluorescent chemosensor for fluoride ions. Moreover, in solid state, seven units of the protonated receptors form a pseudo-capsular cavity to encapsulate two pairs of sulphate anions.
Solvothermal synthesis of graphene oxide and its composites with poly(ε-caprolactone)
Authors: Chin Seow Jecg , Doherty Matthew , Vempati Sesha , Dawson Paul , Byrne Cormac , Meenan Brian J. , Guerra Valentina , McNally Tony
Published: September 2019

Graphene oxide (GO) was prepared by a solvothermal synthesis method using sodium and ethanol.
Hypoxia-induced biosynthesis of gold nanoparticles in the living brain
Authors: Rozhkova Elena A. , Lee Byeongdu , Prasad Judy A. , Liu Yuzi , Shevchenko Elena V.
Published: September 2019

While a large number of studies deal with biomedical applications of various types of nanoparticles synthesized using wet chemistry, we propose the concept of targeted biosynthesis of nanoparticles in the living brain.
Matrix metalloproteinase-2-targeted superparamagnetic Fe3O4-PEG-G5-MMP2@Ce6 nanoprobes for dual-mode imaging and photodynamic therapy
Authors: Duan Meng , Xia Fangfang , Li Tianliang , Shapter Joseph G. , Yang Sheng , Li Yongying , Gao Guo , Cui Daxiang
Published: September 2019

A novel matrix metalloproteinase 2-targeted superparamagnetic nanoprobes for MRI, NIR and photodynamic therapy of tumors have been developed. The nanoprobes can significantly inhibit the tumor growth compared with PBS and free Ce6.
Computational exploration of substrate and ligand effects in nickel-catalyzed C–Si bond carboxylation with CO2
Authors: Lv Xiangying , Zhang Xiaotian , Sa Rongjian , Huang Fang , Lu Gang
Published: September 2019

The ring strain of substrates and steric hindrance of NHC ligands are the key factors affecting the reactivity of CO2 insertion into sila-nickelacycles.
Biorenewable rosin derived benzocyclobutene resin: a thermosetting material with good hydrophobicity and low dielectric constant
Authors: Fu Fei , Wang Dan , Shen Minggui , Shang Shibin , Song Zhanqian , Song Jie
Published: September 2019

The rosin structure was introduced into benzocyclobutene resin for the first time, and the thermosetting material with good hydrophobicity and low dielectric constant was prepared.
SO2F2 mediated cascade dehydrogenative Morita–Baylis–Hillman reaction of the C(sp3)–H of primary alcohols with the C(sp2)–H of electron-deficient olefins for the assembly of allylic alcohols
Authors: Jiang Ying , Alharbi Njud S. , Sun Bing , Qin Hua-Li
Published: September 2019

A cascade dehydrogenative Morita–Baylis–Hillman reaction of the C(sp3)–H of primary alcohols with the C(sp2)–H of electron-deficient olefins for forming allylic alcohols mediated by SO2F2 was developed.
Discovery of diazahexa/hepta cyclic cage-like compounds with broad-spectrum antifungal activity against Candida and Cryptococcus species
Authors: Weinstock Anthony , Arumugam Natarajan , Almansour Abdulrahman I. , Kumar Raju Suresh , Thangamani Shankar
Published: September 2019

The synthesized cage-like compounds has been investigated for their antifungal activity against Candida and Cryptococcus species.
CoFe2O4/Cu(OH)2 magnetic nanocomposite: an efficient and reusable heterogeneous catalyst for one-pot synthesis of β-hydroxy-1,4-disubstituted-1,2,3-triazoles from epoxides
Authors: Eisavi Ronak , Karimi Asmar
Published: September 2019

Magnetically separable CoFe2O4/Cu(OH)2 nanocomposite was prepared and used as a novel heterogeneous catalyst for synthesis of β-hydroxy-1,4-disubstituted-1,2,3-triazoles from epoxides.
The pivotal role of an interconnected cellular conductive structure to manage heat removal in compact Fischer–Tropsch fixed-bed reactors
Authors: Fratalocchi Laura , Groppi Gianpiero , Visconti Carlo Giorgio , Lietti Luca , Tronconi Enrico
Published: September 2019

An interconnected conductive structure is crucial to run FTS in compact reactors under severe conditions, while keeping a remarkably effective T-control.
Microgel PAINT – nanoscopic polarity imaging of adaptive microgels without covalent labelling
Authors: Purohit Ashvini , Centeno Silvia P. , Wypysek Sarah K. , Richtering Walter , Wöll Dominik
Published: September 2019

The 3D structure and the local environment of stimuli-responsive microgels were investigated with the superresolution fluorescence microscopy method PAINT using Nile Red as solvatochromic dye.
Solar-light-driven non-bias photoelectrolysis for bleach production from sea water and atmospheric oxygen
Authors: Iguchi Shoji , Tateno Hiroyuki , Takasugi Soichi , Miseki Yugo , Sayama Kazuhiro
Published: September 2019

Non-bias production of a bleach aqueous solution was successfully demonstrated using a solar-driven photoelectrochemical cell consisting of a metal-oxide-semiconductor photoanode and Pt-based cathode.
Mechanosensitive ion channel inhibitors promote the stiffening of the plasma membrane of mouse sensory neurons
Authors: Reyes-Pardo Humberto , Sánchez-Herrera Daniel P.
Published: September 2019

The interaction of Gd3+, ruthenium red or GsMTx-4 with DRG nociceptive neurons increases the plasma membrane rigidity.
DNA translocation to giant unilamellar vesicles during electroporation is independent of DNA size
Authors: Sachdev Shaurya , Muralidharan Aswin , Choudhary Dipendra K. , Perrier Dayinta L. , Rems Lea , Kreutzer Michiel T. , Boukany Pouyan E.
Published: September 2019

DNA delivery into GUVs during electroporation is governed by bulk electrophoretic mobility implying a mechanism in which DNA molecules enter in their coiled conformation, as opposed to stochastic threading, through electro-pores.
Styrene maleic acid copolymer induces pores in biomembranes
Authors: Orwick Rydmark Marcella , Christensen Mikkel Killingmoe , Köksal Elif Senem , Kantarci Ilayda , Kustanovich Kiryl , Yantchev Ventsislav , Jesorka Aldo , Gözen Irep
Published: September 2019

The experimental observations revealed that the interaction of styrene maleic acid with lipid membranes results in formation of toroidal pores.
Long-term optical spectroscopic variations in blazar 3C 454.3
Authors: Nalewajko Krzysztof , Gupta Alok C. , Liao Mai , Hryniewicz Krzysztof , Gupta Maitrayee , Gu Minfeng
Published: September 2019

Aims. Characterisation of the long-term variations in the broad line region in a luminous blazar, where Comptonisation of broad-line emission within a relativistic jet is the standard scenario for production of γ-ray emission that dominates the spectral energy distribution.

Methods. We analysed ten years of optical spectroscopic data from the Steward Observatory for the blazar 3C 454.3, as well as γ-ray data from the Fermi Large Area Telescope (LAT). The optical spectra are dominated by a highly variable non-thermal synchrotron continuum with a prominent Mg II broad emission line. The line flux was obtained by spectral decomposition including significant contribution from the Fe II pseudo-continuum. Three methods were used to characterise variations in the line flux: (1) stacking of the continuum-subtracted spectra, (2) subtracting the running mean light curves calculated for different timescales, and (3) evaluating potential time delays via the discrete correlation function (DCF).

Results. Despite very large variations in the γ-ray and optical continua, the line flux changes only moderately (<0.1 dex). The data suggest that the line flux responds to a dramatic change in the blazar activity from a very high state in 2010 to a deep low state in 2012. Two interpretations are possible: either the line flux is anti-correlated with the continuum or the increase in the line luminosity is delayed by ∼600 days. If this time delay results from the reverberation of poorly constrained accretion disc emission in both the broad-line region (BLR) and the synchrotron emitting blazar zone within a relativistic jet, we would obtain natural estimates for the BLR radius RBLR, MgII ≳ 0.28 pc and for the supermassive black hole mass MSMBH ∼ 8.5 × 108 M⊙. We did not identify additional examples of short-term “flares” of the line flux, in addition to the previously reported case observed in 2010.
Inversion of asteroid photometry from Gaia DR2 and the Lowell Observatory photometric database
Authors: Ďurech J. , Hanuš J. , Vančo R.
Published: September 2019

Context. Rotation properties (spin-axis direction and rotation period) and coarse shape models of asteroids can be reconstructed from their disk-integrated brightness when measured from various viewing geometries. These physical properties are essential for creating a global picture of structure and dynamical evolution of the main belt.

Aims. The number of shape and spin models can be increased not only when new data are available, but also by combining independent data sets and inverting them together. Our aim was to derive new asteroid models by processing readily available photometry.

Methods. We used asteroid photometry compiled in the Lowell Observatory photometry database with photometry from the Gaia Data Release 2. Both data sources are available for about 5400 asteroids. In the framework of the Asteroids@home distributed computing project, we applied the light curve inversion method to each asteroid to find its convex shape model and spin state that fits the observed photometry.

Results. Due to the limited number of Gaia DR2 data points and poor photometric accuracy of Lowell data, we were able to derive unique models for only ∼1100 asteroids. Nevertheless, 762 of these are new models that significantly enlarge the current database of about 1600 asteroid models.

Conclusions. Our results demonstrate the importance of a combined approach to inversion of asteroid photometry. While our models in general agree with those obtained by separate inversion of Lowell and Gaia data, the combined inversion is more robust, model parameters are more constrained, and unique models can be reconstructed in many cases when individual data sets alone are not sufficient.
Attitude Blended Control for Aerospace Vehicle with Lateral Thrusters and Aerodynamic Fins
Authors: Li Aijun , Wang Yu , Guo Yong , Wang Changqing
Published: September 2019

A finite-time blended control strategy is proposed for the reentry phase attitude control of the aerospace vehicle (ASV) based on the neural network, sliding mode control theory and control allocation. Firstly, a finite-time neural networks sliding mode controller is designed based on the attitude model of the ASV in the reentry phase to obtain the virtual control moments which can make the attitude error converge to the equilibrium point in finite time. Secondly, the desired control moments are mapped into the control commands on the aerodynamic deflectors and the reaction control system (RCS) by using the control allocation. Finally, simulation results are provided to demonstrate the effectiveness of the attitude blended control strategy proposed.
Detection and Recognition of SAR Small Ship Objects Using Deep Neural Network
Authors: Wei Songjie , Jiang Pengfei , Yuan Qiuzhuang , Liu Meilin
Published: September 2019

Synthetic aperture radar(SAR) ship target detection plays an increasingly important role in marine monitoring. Aimed at the problems of recognizing small size of ship targets in SAR images and the inability of traditional methods to extract fine target features due to external disturbances, we propose an improved SAR small target detection model based on the deep learning technology. The proposed model mainly consists of two parts:region proposal network(RPN) and object detection network. Firstly, a CNN model is designed and trained to accurately identify small ship targets. Then, the model is used to initialize the parameters of the shared feature extraction layer. Last, we train the proposed object detection model using a self-collected Sentinel-1 SAR small target dataset. The experimental results show that the proposed target detection model has better detection and recognition performance and anti-interference ability for small ship scalable targets in SAR images, and has certain reference value for the research of small target detection in SAR images.
Research on Formation Reconfiguration of UAVs Based on RRT Algorithm
Authors: Li Yue , Han Wei , Chen Qingyang , Zhang Yong
Published: September 2019

To adapt the complexity and flexibility of battlefield environment, a method of formation reconfiguration based on Rapidly-exploring Random Tree (RRT) algorithm is proposed, which shows the advantage of formation of Unmanned Aerial Vehicles (UAVs). Firstly, the kinematic model for UAVs is built, and the feasibility of combination of traditional RRT algorithm and formation reconfiguration of UAVs is analyzed. Secondly, the strategies of trajectory correction comprising node removal and transition trajectory are adopted. Then the dynamic and collision avoidance constraints are discussed respectively, which are essential for exploring the process of RRT algorithm as well as adjusting the trajectory of UAVs. Finally, the simulation and flight experiment are carried out to verify the effectiveness of the proposed method. The results show that the reconfiguration method is able to achieve the formation reconfiguration rapidly and safely. Moreove, the planed trajectory can satisfy the tracing requirement, which is of significance for flight of UAVs in the battlefield environment.
A design methodology for additive manufacturing applied to fused deposition modeling process
Authors: Nicolas Boyard , Olivier Christmann , Mickael Rivette , Simon Richir
Published: September 2019

The aim of this article is to propose a design methodology for the production of parts in additive manufacturing (AM). The AM process allows new features (e.g., multi-material, fixed assemblies, complex shapes), and this paradigm shift requires the accompaniment of designers to take account of these characteristics. In response to this problematic, we propose a design methodology, in three stages, which respects the integrity of the digital channel and whose purpose is to provide a digital mock-up sliced ready to be manufactured on the most common AM process (Fused Deposition Modeling). From the specifications and the process knowledge, our methodology provides the designer a first solid geometry which satisfies all the constraints. Then, a topology optimization limits the useful volume of material of the part in order to limit the weight and the manufacturing time. If necessary, an optimized support providing manufacturability of the part is generated according to the same criteria. The methodology we propose is applied to a real industrial part.
A full investigation of the directional congestion in data envelopment analysis
Authors: Khezri Somayeh , Dehnokhalaji Akram , Hosseinzadeh Lotfi Farhad
Published: September 2019

One of interesting subjects in Data Envelopment Analysis (DEA) is estimation of congestion of Decision Making Units (DMUs). Congestion is evidenced when decreases (increases) in some inputs result in increases (decreases) in some outputs without worsening (improving) any other input/output. Most of the existing methods for measuring the congestion of DMUs utilize the traditional definition of congestion and assume that inputs and outputs change with the same proportion. Therefore, the important question that arises is whether congestion will occur or not if the decision maker (DM) increases or decreases the inputs dis-proportionally. This means that, the traditional definition of congestion in DEA may be unable to measure the congestion of units with multiple inputs and outputs. This paper focuses on the directional congestion and proposes methods for recognizing the directional congestion using DEA models. To do this, we consider two different scenarios: (i) just the input direction is available. (ii) none of the input and output directions are available. For each scenario, we propose a method consists in systems of inequalities or linear programming problems for estimation of the directional congestion. The validity of the proposed methods are demonstrated utilizing two numerical examples.
Historically, did Cemented Thompson perform better than uncemented Austin Moore hemiarthroplasty for femoral neck fractures? A meta-analysis of available evidence
Authors: Shehata Mohamed S.A. , Abdelal Ahmed , Salahia Sami , Ahmed Hussien , Shawqi Muhammad , Elsehili Ahmed , Morsi Mahmoud , Afifi Ahmed M. , Kader Nardeen , Grubhofer Florian , Sallam Asser , Imam Mohamed
Published: September 2019

Introduction: Thompson and Austin Moore prostheses have been commonly used in hemiarthroplasties for displaced femoral neck fractures. There has been considerable debate about which of these prostheses is preferred. The purpose of this meta-analysis was to compare historical data for clinical outcomes of cemented Thompson and uncemented Austin Moore hemiarthroplasty in displaced femoral neck fractures.

Methods: We searched Medline via PubMed, Cochrane Central, Scopus, Ovid and Web of Science for relevant articles up to February 2019. The included outcomes measured were hip function, hip pain, implant-related complications, surgical complications, reoperation rate and hospital stay. The data were pooled as risk ratio (RR) or mean difference (MD) with 95% confidence interval (CI) between the two compared groups in a meta-analysis model.

Results: Ten studies (four RCTs and six observational studies) with a total of 4378 patients were included in the final analysis. The pooled RR showed that the Thompson group was associated with a lower incidence of postoperative hip pain (RR = 0.66, 95% CI [0.54, 0.80]), lesser reoperation rate (RR = 0.46, 95% CI [0.24, 0.88]), lesser intraoperative fractures (RR = 0.15, 95% CI [0.09, 0.25]), but a longer operative time (MD = 12.04 min, 95% CI [2.08, 22.00]) in comparison to the Austin Moore group. The effect estimate did not favour either group in terms of hip function, periprosthetic fractures, prosthetic dislocations, wound infection, mortality and hospital stay.

Conclusion: Evidence shows that Thompson hemiarthroplasty is better than Austin Moore hemiarthroplasty in terms of hip pain, reoperation rate and intraoperative fractures. Whereas the postoperative hip function is equivalent, these results could be considered when assessing the outcomes in modern hips.
Monoamine Oxidase Inhibition by Kavalactones from Kava (Piper Methysticum)
Authors: Prinsloo Denise , van Dyk Sandra , Petzer Anél , Petzer Jacobus P.
Published: September 2019

Monoamine oxidases (MAOs) are key metabolic enzymes for neurotransmitter and dietary amines and are targets for the treatment of neuropsychiatric and neurodegenerative disorders. This study examined the MAO inhibition potential of kavain and other kavalactones from the roots of kava (Piper methysticum), a plant that has been used for its anxiolytic properties. (±)-Kavain was found to be a good potency in vitro inhibitor of human MAO-B with an IC50 of 5.34 µM. (±)-Kavain is a weaker MAO-A inhibitor with an IC50 of 19.0 µM. Under the same experimental conditions, the reference MAO inhibitor, curcumin, displays IC50 values of 5.01 µM and 2.55 µM for the inhibition of MAO-A and MAO-B, respectively. It was further established that (±)-kavain interacts reversibly and competitively with MAO-A and MAO-B with enzyme-inhibitor dissociation constants (Ki) of 7.72 and 5.10 µM, respectively. Curcumin in turn, displays a Ki value of 3.08 µM for the inhibition of MAO-A. Based on these findings, other kavalactones (dihydrokavain, methysticin, dihydromethysticin, yangonin, and desmethoxyyangonin) were also evaluated as MAO inhibitors in this study. Yangonin proved to be the most potent MAO inhibitor with IC50 values of 1.29 and 0.085 µM for MAO-A and MAO-B, respectively. It may be concluded that some of the central effects (e.g., anxiolytic) of kava may be mediated by MAO inhibition.
Velopharyngeal Closure and Resonance in Children Following Early Cleft Palate Repair: Outcome Measurement
Authors: Aparna V. S. , Pushpavathi M. , Bonanthaya Krishnamurty
Published: September 2019

Introduction Timing of cleft palate repair and the method of speech outcome measurement in children with cleft lip and palate are much debated topics. The associated problems and quality of life in these children depend on the timing of the surgery.

Aim The aim of this study was to investigate the velopharyngeal (VP) function and resonance parameters in children following early cleft palate repair.

Method A total of 25 Kannada-speaking children with early repaired cleft palate were subjected to speech assessment and videofluoroscopic assessment. Perceptual speech parameters measured were severity of hypernasality and presence of nasal air emission. Videofluoroscopy was interpreted in terms of closure ratios to predict the severity of VP dysfunction.

Results The analysis of videofluoroscopic images indicated that 48% of children had complete VP closure and 52% had perceptually normal resonance. A good correlation was found between the closure ratio and hypernasality.

Conclusion Understanding the perceptual speech parameters and their structural correlates for outcome measurement will give better evidence for refining the existing treatment protocols. Data on a larger population are warranted for establishing predictors of optimum speech outcome.
Medical Therapy for Eisenmenger Syndrome: A Case Report and Review of Literature
Authors: Pradhan Akshyaya , Vohra Shweta , Vishwakarma Pravesh , Sethi Rishi
Published: September 2019

Eisenmenger syndrome (ES) is defined as the process in which a long-standing left-to-right cardiac shunt caused by a congenital heart defect is eventually reversed into a cyanotic right-to-left shunt. It is crucial to recognize this grave pathology at the earliest because once it develops, treatment by medical or surgical means becomes even more challenging. In past decades, various therapeutic options have been developed that address the specific pathophysiological aspects of the disease and have shown to improve functional capacity and quality of life. There are three major therapeutic pathways in pulmonary hypertension treatment - endothelin receptor antagonists, phosphodiesterase type-5 inhibitors, and prostacyclin derivatives. These therapies not only improve hemodynamic parameters and exercise capacity but they also improve prognosis with various form of Pulmonary hypertension including ES. We report a case of a 35-year-old female of ostium secundum atrial septal defect with ES, started on upfront combination therapy of ambrisentan and tadalafil who demonstrated marked improvement after 3 months of medical therapy.
Non-iterative characteristics analysis for high-pressure ramp loading
Authors: Swift Damian C. , Fratanduono Dayne E. , Kraus Richard G. , Dowling Evan A.
Published: September 2019

In the canonical ramp compression experiment, a smoothly increasing load is applied to the surface of the sample, and the particle velocity history is measured at two or more different distances into the sample, at interfaces where the surface of the sample can be probed. The velocity histories are used to deduce a stress-density relation, usually using iterative Lagrangian analysis to account for the perturbing effect of the impedance mismatch at the interface. In that technique, a stress-density relation is assumed in order to correct for the perturbation and is adjusted until it becomes consistent with the deduced stress-density relation. This process is subject to the usual difficulties of nonlinear optimization, such as the existence of local minima (sensitivity to the initial guess), possible failure to converge, and relatively large computational effort. We show that, by considering the interaction of successive characteristics reaching a free surface, the stress-density relation can be deduced directly by recursion rather than iteration. This calculation is orders of magnitude faster than iterative analysis and does not require an initial guess. Direct recursion may be less suitable for very noisy data, but it was robust when applied to trial data. The stress-density relation deduced was identical to the result from iterative Lagrangian analysis.
The pulsed X-ray radiation source based on a semiconductor opening switch with the focal point diameter of 0.5 mm and its application
Authors: Komarskiy A. , Korzhenevskiy S. , Chepusov A. , Krasniy O.
Published: September 2019

This investigation is devoted to developing a pulsed X-ray radiation source. The high-voltage pulse generator is based on an inductive energy storage unit and a semiconductor opening switch, and the latter ensures a high pulse repetition rate. A high-voltage pulse generator has the following parameters: the pulse voltage amplitude up to 120 kV, the pulse current up to 180 A, the current pulse duration at 50% of the peak height of about 20 ns, and the pulse repetition rate up to 5 kHz. The source works consistently when the pulse repetition rate is increased. We developed the designs of an anode and an explosive emission cathode for the pulsed X-ray tube with the focal point of 0.5 mm, used in the experiments. The setup which makes it possible to investigate demountable models of pulsed X-ray tubes is described in this paper. We believe there are advantages of using an X-ray source with the flare duration of about 20 ns and the pulse repetition rate up to 5 kHz over continuously working X-ray sources. The source is unique for some problems, such as studying high-speed processes. The experiments have shown that a pulsed X-ray source works consistently together with a digital detector, and the generation of X-ray flares is easily synchronized with the detector and the rotation system. In the article, we discuss the issues of reducing image blurring for computerized tomography purposes, caused by fast rotation of the source and the detector relative to the object of investigation and reducing the radiation exposure of the investigated object. We also set further objectives of the investigation and present perspectives and limitations of this source.
Presenting q-Schur algebras as quotients of the quantized enveloping algebra of sln
Authors: Gao Wenting , Liu Mingqiang
Published: September 2019

In the work of Doty and Giaquinto [Int. Math. Res. Not. 36, 1907 (2002)] and Du and Parshall [Trans. Am. Math. Soc. 355, 1593 (2003)], the presentations of q-Schur algebra as a quotient of quantum gln are given. Doty and Giaquinto [Electron. Res. Announce. Am. Math. Soc. 7, 54 (2001)] obtained the presentation for the Schur algebra U(2, r) and q-Schur algebra U(2, r) as a quotient of classical, quantized enveloping algebra of sl2, respectively. They pointed out that the problem of presenting q-Schur algebra U(n, r) as a quotient of quantized enveloping algebra of sln seems to be more difficult for n > 2. Inspired by this point of view, we obtain a presentation for the Schur algebra, both the classical and quantized case, as a quotient of classical, quantized enveloping algebra of sln, respectively, in this paper.
Sampling the thermal Wigner density via a generalized Langevin dynamics
Authors: Plé Thomas , Huppert Simon , Finocchi Fabio , Depondt Philippe , Bonella Sara
Published: September 2019

The Wigner thermal density is a function of considerable interest in the area of approximate (linearized or semiclassical) quantum dynamics where it is employed to generate initial conditions for the propagation of appropriate sets of classical trajectories. In this paper, we propose an original approach to compute the Wigner density based on a generalized Langevin equation. The stochastic dynamics is nontrivial in that it contains a coordinate-dependent friction coefficient and a generalized force that couples momenta and coordinates. These quantities are, in general, not known analytically and have to be estimated via auxiliary calculations. The performance of the new sampling scheme is tested on standard model systems with highly nonclassical features such as relevant zero point energy effects, correlation between momenta and coordinates, and negative parts of the Wigner density. In its current brute force implementation, the algorithm, whose convergence can be systematically checked, is accurate and has only limited overhead compared to schemes with similar characteristics. We briefly discuss potential ways to further improve its numerical efficiency.
Algorithms for quantum control without discontinuities: Application to the simultaneous control of two qubits
Authors: D’Alessandro Domenico , Sheller Benjamin
Published: September 2019

We propose a technique to design control algorithms for a class of finite dimensional quantum systems so that the control law does not present discontinuities. The class of models considered admits a group of symmetries, which allows us to reduce the problem of control to a quotient space where the control system is “fully actuated.” As a result, we can prescribe a desired trajectory, which is, to some extent, arbitrary, and derive the corresponding control. We illustrate this technique with examples and focus on the application to the simultaneous control of two non-interacting spin 12 particles with different gyromagnetic ratios in zero field nuclear magnetic resonance (NMR). Our method provides a flexible toolbox for the design of control algorithms to drive the state of finite dimensional quantum systems to any desired final configuration, with smooth controls.
Optimizing magnetoresistive sensor signal-to-noise via pinning field tuning
Authors: Moulin J. , Doll A. , Paul E. , Pannetier-Lecoeur M. , Fermon C. , Sergeeva-Chollet N. , Solignac A.
Published: September 2019

The presence of magnetic noise in magnetoresistive-based magnetic sensors degrades their detection limit at low frequencies. In this paper, different ways of stabilizing the magnetic sensing layer to suppress magnetic noise are investigated by applying a pinning field, either by an external field, internally in the stack, or by shape anisotropy. We show that these three methods are equivalent, could be combined, and that there is a competition between noise suppression and sensitivity reduction, which results in an optimum total pinning field for which the detection limit of the sensor is improved up to a factor of 10.
Thermocouple-tip-exposing temperature assessment technique for evaluating photothermal conversion efficiency of plasmonic nanoparticles at low laser power density
Authors: Yuan Muzhaozi , Wang Ya , Hwang David , Longtin Jon P.
Published: September 2019

A new thermocouple (TC) tip-exposing temperature assessment technique that combines experimental temperature measurements with a numerical model of the photothermal conversion efficiency η is presented. The proposed technique is designed to evaluate η for a gold-coated superparamagnetic iron oxide nanoparticle (SPIO-Au NP) solution (26 nm, 12–70 ppm) at low continuous wave laser power (103 mW, 532 nm) irradiation in a convenient manner under ambient conditions. The TC tip temperature is measured during the first 30 s of the laser exposure, and the results are combined with a finite element model to simulate the temperature rise of the NP solution for a given concentration. The value of η is adjusted in the model until the model agrees with the measured transient TC temperature rise. Values of η = 1.00 were observed for all concentrations. Theoretical predictions of η derived by Mie theory confirmed the near unity conversion efficiency of the as-synthesized SPIO-Au NPs. Advantages of the current technique include co-locating the TC tip in the geometric center of the laser-heated region, rather than outside of this region. In addition, the technique can be done under ambient room conditions using unmodified commercially available hardware.
In Vitro Visualization of Ultrasonic Wave Fronts Interacting with Heel Bones Using Refracto-Vibrometry
Authors: Huber Matthew , Huber Nathan , Hoffmeister Brent , Huber Thomas
Published: September 2019

Ultrasonic measurements of the heel bone (calcaneus) are used commonly for osteoporosis screening. Pulses emitted by an ultrasound transducer are incident on the calcaneus, and the transmitted wave fronts are detected with a separate transducer. In the current study, full field videos were obtained using refracto-vibrometry of ultrasonic pulses interacting human calcaneus samples in an in vitro environment. Pulses were emitted by a 500 kHz Panametrics V303 transducer. The measurement beam from a Polytec PSV-400 scanning laser Doppler vibrometer laser was directed through a water tank towards a stationary retroreflective surface. Acoustic wave fronts (density variations) which pass through the measurement laser cause variations in the integrated optical path length. The time-varying signals detected by the vibrometer at numerous scan points were used to determine the time evolution of ultrasonic wave fronts. The resulting videos enable visualization of the propagating wave fronts and the backscattered and transmitted wave fronts. These videos enable direct investigation of wave front distortion due to reflection, refraction and diffraction effects
A Brief Introduction to Plasma Accelerators
Authors: Lee Valentina , Oganyan Bagrad
Published: September 2019

This work describes the physics of plasma waves and plasma accelerators. The superiority of plasma accelerators over conventional accelerators has generated renewed interest in these devices with the advent of ultra-fast laser technology. The ponderomotive force produced by ultra short laser pulses interacting with the plasma is considered and the resulting acceleration gradient is derived from first principles. Electron injection is described. Beam driven, including electron beam and proton beam, plasma waves are proposed as the future of high energy plasma accelerators.
Radiation Shielding Using Magnetic Fields
Authors: Sailer M. W. , Doss H. M.
Published: September 2019

Radiation shielding is essential to future space exploration missions with longer exposure to space radiation. High Atomic Number and Energy particles (HZE) in Galactic Cosmic Radiation (GCR) presents one of the most difficult types of radiation to shield. We propose a combination of active and passive shielding to maximize deflection of radiation and minimize production of secondary radiation, while creating a possibility of usable power. The focus of this paper is on the 7687 kg wire design and the 0.57 T magnetic field created, with less than 2 G in the crew area, and its ability to deflect a 2800 GeV iron ion. Estimates of trapped plasma reducing the iron ion to 140 GeV, as well as thrust production of 34 N are presented.
Stochastic perturbation theory in a limited configuration space
Authors: Ladóczki Bence , Ten-no Seiichiro L.
Published: September 2019

A general-order stochastic perturbation algorithm is obtained from the order-by-order expansion of the imaginary-time evolution of a configuration interaction wave function. A truncation of configuration space that is required for the practical treatment of the perturbative corrections, however, does not preserve size-consistency as is the case for a truncated configuration interaction. To circumvent this problem, we formulate a linked variant of stochastic perturbation theory based on the coupled-cluster ansatz. The implementation based on the linearized coupled-cluster is compared with several full configuration interaction results. We also compare the results with those obtained from deterministic coupled-cluster and many-body perturbation theories.
Ab initio simulations of complementary K-edges and solvatization effects for detection of proton transfer in aqueous 2-thiopyridone
Authors: Norell J. , Eckert S. , Van Kuiken B. E. , Föhlisch A. , Odelius M.
Published: September 2019

The nitrogen and sulfur K-edge X-ray absorption spectra of aqueous 2-thiopyridone, a model system for excited-state proton transfer in several recent time-resolved measurements, have been simulated from ab initio molecular dynamics. Spectral signatures of the local intra- and inter-molecular structure are identified and rationalized, which facilitates experimental interpretation and optimization. In particular, comparison of aqueous and gas phase spectrum simulations assesses the previously unquantified solvatization effects, where hydrogen bonding is found to yield solvatochromatic shifts up to nearly 1 eV of the main peak positions. Thereby, while each K-edge can still decisively determine the local protonation of its core-excited site, only their combined, complementary fingerprints allow separating all of the three relevant molecular forms, giving a complete picture of the proton transfer.
Reconfigurable metalattices: Combining multipolar lattice resonances and magneto-optical effect in far and near fields
Authors: Liu M. Q. , Zhao C. Y.
Published: September 2019

The present work has elaborated the roles of near- and far-field lattice resonances (LRs) in the performance of one-dimensional metalattices composed of magneto-optically (MO) coated cylinders. By taking advantage of LR effects and MO-modified multipolar interferences, it is feasible to alter transmission or reflection with unity efficiency by turning on or off external magnetic fields. In the far field, multipolar LRs near Rayleigh anomaly (RA) can be acquired, leading to transmission suppression or enhancement for different multipolar interference mechanisms. Meanwhile, thanks to exciting degeneracy-broken multipoles, asymmetric diffractive patterns are observed despite normal incidence. However, in the diffractionless region with strong near-field couplings, we find that LR effects are capable of not only modifying scattering amplitude (>1) but also introducing phase change or even inversion. Specifically, owing to the appearance of π/2-phase rotated electric dipoles, the first and second Kerker conditions are achieved simultaneously in this work. In addition, the coupling mechanism of RA-associated LRs and MO-influenced Mie modes supported by an individual cylinder is also unveiled. Besides, a proof-of-concept example using realistic Si@InSb metalattices has also been demonstrated, showing reconfigurable performance as expected. The revealed far/near-field mechanism of interplay between LRs and MO-modified multipoles will shed new light on wavefront engineering with diffracted effects and reconfigurable features.
Dielectric response of electric-field distortions of the twist-bend nematic phase for LC dimers
Authors: Merkel K. , Welch C. , Ahmed Z. , Piecek W. , Mehl G. H.
Published: September 2019

Wide band dielectric spectroscopy of bent-shaped achiral liquid-crystal dimers 1″-n″-bis(4-cyanobiphenyl-4′-yl) n-alkanes (CBnCB n = 7, 9, 11) has been investigated in a frequency range 0.1 Hz–100 MHz using planar-aligned cells of sample thicknesses ranging from 2 to 10 (μm) over a temperature range that covers both nematic and twist bend nematic phases. Two peaks in the dielectric spectrum in the higher frequency range are assigned to the molecular relaxation processes. The peak at the highest frequency, ∼40 to 80 MHz, is assigned to an internal precessional rotation of a single unit of the dimer around the director. The mode in the next lower frequency range of 2–10 MHz is assigned to the spinning rotation of the dimer around its long axis. This involves fluctuations of the dipole moment of the bent-shaped conformation that is directed along its arrow direction of the bow shape formed by the dimer. The peak in the frequency range 100 kHz–1 MHz can be assigned to the collective fluctuations of the local director with reference to the helical axis of the NTB structure. The dependence of its frequency on temperature is reminiscent of the soft mode observed at the SmA* to SmC* phase transition. This result clearly corresponds to the electro-clinic effect—the response of the director to the applied electric field in an electro-optic experiment. The lowest frequency mode, observed in the frequency range of 0.1 Hz–100 Hz, is identified with the Goldstone mode. This mode is concerned with the long range azimuthal angle fluctuations of the local director. This leads to an alternating compression and expansion of the periodic structure of the NTB phase.
Energy window stochastic density functional theory
Authors: Chen Ming , Baer Roi , Neuhauser Daniel , Rabani Eran
Published: September 2019

Linear scaling density functional theory is important for understanding electronic structure properties of nanometer scale systems. Recently developed stochastic density functional theory can achieve linear or even sublinear scaling for various electronic properties without relying on the sparsity of the density matrix. The basic idea relies on projecting stochastic orbitals onto the occupied space by expanding the Fermi-Dirac operator and repeating this for Nχ stochastic orbitals. Often, a large number of stochastic orbitals are required to reduce the statistical fluctuations (which scale as Nχ−1/2) below a tolerable threshold. In this work, we introduce a new stochastic density functional theory that can efficiently reduce the statistical fluctuations for certain observable and can also be integrated with an embedded fragmentation scheme. The approach is based on dividing the occupied space into energy windows and projecting the stochastic orbitals with a single expansion onto all windows simultaneously. This allows for a significant reduction of the noise as illustrated for bulk silicon with a large supercell. We also provide theoretical analysis to rationalize why the noise can be reduced only for a certain class of ground state properties, such as the forces and electron density.
Hybridized plasmon modes in a system of metal thin film–nanodisk array
Authors: Yildiz B. C. , Habib M. , Rashed A. R. , Caglayan H.
Published: September 2019

Controlling the hybridization is a very powerful tool to manipulate the modes in a single nanostructure. We investigate the hybridization between localized and propagating surface plasmons in a nanostructure system where a thin metal layer strongly interacts with a nanodisk array. Hybrid plasmon resonances are observed in the reflection spectra obtained from finite-difference time domain simulations and experimental measurements in the visible-near-infrared region. We demonstrate how the geometrical parameters of the nanostructure can be utilized to bring these plasmon modes in the strong coupling regime. The hybrid plasmon modes exhibit anticrossing with a Rabi splitting of ∼0.1eV, which is the signature of strong coupling. Near-field profiles of the hybrid modes exhibit a mixture of localized and propagating plasmon characteristics, with propagating modes excited on both sides of the metal film. Our design promises richer implementations in light manipulation towards novel photonic applications compared to the systems with thick metal films.
Artificially structured boundary plasma trap
Authors: Hedlof R. M. , Ordonez C. A.
Published: September 2019

A computer simulation is presented of single-species non-neutral plasma confinement using an artificially structured boundary. The artificially structured boundary produces a spatially periodic static electromagnetic field along the plasma periphery such that the spatial period of the applied field is much smaller than the dimensions of the confined plasma. The simulated non-neutral plasma self-consistently produces an electrostatic potential energy well for oppositely signed charged particles. The results support the prospect of developing plasma space-charge based confinement, with an unmagnetized plasma of one species of charged particles confined by an electric field produced by an edge-confined plasma of a second species of charged particles. The Warp particle-in-cell code is used for the simulations.
Solvated electron formation from the conduction band of liquid methanol: Transformation from a shallow to deep trap state
Authors: Hara Ayano , Yamamoto Yo-ichi , Suzuki Toshinori
Published: September 2019

We report solvated electron (esolv−) formation dynamics from the conduction band of liquid methanol studied using femtosecond time-resolved photoelectron spectroscopy. Liquid methanol is excited with vacuum UV (9.3 eV) pump pulses, and the subsequent electron dynamics are probed with UV pulses. The photoelectron signal exhibits a short-lived component (τ = 85 fs) without spectral evolution followed by a long-lived component with continuous spectral evolution over tens of picoseconds. We ascribe the former to a superexcited state, most likely the Wannier exciton, and the latter to the ground electronic state of esolv−. In order to extract accurate energetics from the observed photoelectron spectra, we employ a spectral retrieval method to account for spectral broadening and shifting due to inelastic scattering of photoelectrons in the liquid. The electron binding energy (eBE) of the initial trap state of an electron is determined to be about 1.5 eV, and its biexponential increase up to 3.4 eV is observed with time constants of 2 and 31 ps, which are greater than 0.27 and 13 ps observed for esolv− created by the charge-transfer-to-solvent reaction from CH3O− to liquid methanol. The solvation dynamics of esolv− created by the electron trapping exhibit a pseudoisosbestic point at a pump-probe delay time of around 15 ps, and the peak energy of the eBE distribution rapidly changes around that time. These results indicate that there exist two trap states, both of which exhibit increasing eBE with time; however, the eBE of the shallow trap state increases only up to 2.1 eV, and transformation to a deep trap state at 25 ps occurs to reach an eBE of 3.4 eV.
The first and second laws of thermodynamics
Authors: Swaney Ross E. , Bird R. Byron
Published: September 2019

This article summarizes an alternative approach to the formulation of the laws of thermodynamics by making use of the conservation equations of transport phenomena. The principal novel element is the inclusion of the law of conservation of momentum in the derivations. This enables one to make the statement of the first and second laws more complete by including terms describing viscous dissipation of energy.