bluuebunny/crossref_metadata_2025 huggingface dataset:
Advantages of a curved image plate for rapid laboratory-based x-ray total scattering measurements: Application to pair distribution function analysis
Authors: Irving Daniel J. M. , Keen David A. , Light Mark E.
Published: April 2021

The analysis and interpretation of the pair distribution function (PDF), as derived from total scattering measurements, is still seen by many as a technique confined to central synchrotron and neutron facilities. This situation has begun to change with a rising visibility of total scattering experiments reported in mainstream scientific journals and the modification of an increasing number of laboratory diffractometers. However, the rigor required during data reduction and the complexities of data interpretation mean the technique is still very far from being routine. Herein, we report the first application of a large area curved image plate system based on a Rigaku SPIDER (R-AXIS RAPID II) equipped with an Ag tube for collecting data amenable to high quality PDF refinement/modeling of crystalline, amorphous, and liquid samples. The advantages of such a system are the large Q range available without scanning (routinely in excess of 20 Å−1) and the inherent properties of an image plate detector (single photon sensitivity, large dynamic range [1.05 × 106], and effectively zero noise). Data are collected and structural models refined for a number of standard materials including NIST 640f silicon for which a Rwp ≤ 0.12 value was obtained with data collected in 60 min (excluding background measurements). These and other data are discussed and compared to similar examples in the literature.
An x-ray penumbral imager for measurements of electron–temperature profiles in inertial confinement fusion implosions at OMEGA
Authors: Adrian P. J. , Frenje J. , Aguirre B. , Bachmann B. , Birkel A. , Johnson M. Gatu , Kabadi N. V. , Lahmann B. , Li C. K. , Mannion O. M. , Martin W. , Mohamed Z. L. , Regan S. P. , Rinderknecht H. G. , Scheiner B. , Schmitt M. J. , Séguin F. H. , Shah R. C. , Sio H. , Sorce C. , Sutcliffe G. D. , Petrasso R. D.
Published: April 2021

Hot-spot shape and electron temperature (Te) are key performance metrics used to assess the efficiency of converting shell kinetic energy into hot-spot thermal energy in inertial confinement fusion implosions. X-ray penumbral imaging offers a means to diagnose hot-spot shape and Te, where the latter can be used as a surrogate measure of the ion temperature (Ti) in sufficiently equilibrated hot spots. We have implemented a new x-ray penumbral imager on OMEGA. We demonstrate minimal line-of-sight variations in the inferred Te for a set of implosions. Furthermore, we demonstrate spatially resolved Te measurements with an average uncertainty of 10% with 6 μm spatial resolution.
Progress and perspectives on phononic crystals
Authors: Vasileiadis Thomas , Varghese Jeena , Babacic Visnja , Gomis-Bresco Jordi , Navarro Urrios Daniel , Graczykowski Bartlomiej
Published: April 2021

Phononic crystals (PnCs) control the transport of sound and heat similar to the control of electric currents by semiconductors and metals or light by photonic crystals. Basic and applied research on PnCs spans the entire phononic spectrum, from seismic waves and audible sound to gigahertz phononics for telecommunications and thermal transport in the terahertz range. Here, we review the progress and applications of PnCs across their spectrum, and we offer some perspectives in view of the growing demand for vibrational isolation, fast signal processing, and miniaturization of devices. Current research on macroscopic low-frequency PnCs offers complete solutions from design and optimization to construction and characterization, e.g., sound insulators, seismic shields, and ultrasonic imaging devices. Hypersonic PnCs made of novel low-dimensional nanomaterials can be used to develop smaller microelectromechanical systems and faster wireless networks. The operational frequency, compactness, and efficiency of wireless communications can also increase using principles of optomechanics. In the terahertz range, PnCs can be used for efficient heat removal from electronic devices and for novel thermoelectrics. Finally, the introduction of topology in condensed matter physics has provided revolutionary designs of macroscopic sub-gigahertz PnCs, which can now be transferred to the gigahertz range with advanced nanofabrication techniques and momentum-resolved spectroscopy of acoustic phonons.
The effective potential of an M-matrix
Authors: Filoche Marcel , Mayboroda Svitlana , Tao Terence
Published: April 2021

In the presence of a confining potential V, the eigenfunctions of a continuous Schrödinger operator −Δ + V decay exponentially with the rate governed by the part of V, which is above the corresponding eigenvalue; this can be quantified by a method of Agmon. Analogous localization properties can also be established for the eigenvectors of a discrete Schrödinger matrix. This note shows, perhaps surprisingly, that one can replace a discrete Schrödinger matrix by any real symmetric Z-matrix and still obtain eigenvector localization estimates. In the case of a real symmetric non-singular M-matrix A (which is a situation that arises in several contexts, including random matrix theory and statistical physics), the landscape function u = A−11 plays the role of an effective potential of localization. Starting from this potential, one can create an Agmon-type distance function governing the exponential decay of the eigenfunctions away from the “wells” of the potential, a typical eigenfunction being localized to a single such well.
Radial profile measurement with an improved 1 kHz Thomson scattering system on Versatile Experiment Spherical Torus
Authors: Kim Jung-Hwa , Kim Young-Gi , Kim Doyeon , Lee Jong-ha , Hwang Y. S.
Published: April 2021

A Thomson scattering (TS) system has been utilized to measure the electron temperature and density of the core region of Versatile Experiment Spherical Torus (VEST). Recently, the laser injection system is successfully upgraded adopting the burst laser with the repetition rate of 1 kHz and the energy of 2 J. Furthermore, improved collection optics with additional polychromators and a 32-channel fast digitizer are prepared to observe the fast time evolution of radial profiles. This improvement is essential to study fast phenomena such as internal reconnection event (IRE). We increase the TS signal and reduce the stray light by introducing new filters having better optical properties such as high optical density at 1064 nm, transmission, and reflectance. Moreover, the optimum reverse bias voltages are newly set to make the system operational independent of the background radiation. As a result, 1 kHz radial profiles of the core electron temperature and density are measured for the first time, showing characteristics of IREs in VEST.
Unraveling exciton processes in Ir(ppy)3:CBP OLED films upon photoexcitation
Authors: Sanderson Stephen , Vamvounis George , Mark Alan E. , Burn Paul L. , White Ronald D. , Philippa Bronson W.
Published: April 2021

Emissive layers in phosphorescent organic light-emitting diodes commonly make use of guest–host blends such as Ir(ppy)3:CBP to achieve high external quantum efficiencies. However, while the Ir(ppy)3:CBP blend has been studied experimentally, crucial questions remain regarding how exciton diffusion is dependent on the distribution of the guest in the host, which can currently only be addressed at the atomic level via computational modeling. In this work, kinetic Monte Carlo simulations are utilized to gain insight into exciton diffusion in Ir(ppy)3:CBP blend films. The effects of both guest concentration and exciton density on various system properties are analyzed, including the probability of singlet excitons being converted to triplets, and the probability of those triplets decaying radiatively. Significantly, these simulations suggest that triplet diffusion occurs almost exclusively via guest–guest Dexter transfer and that concentration quenching of triplets induced by guest–guest intermolecular dipole-dipole interactions has a negligible effect at high exciton densities due to the prevalence of triplet–triplet annihilation. Furthermore, results for vacuum deposited morphologies derived from molecular dynamics simulations are compared to the results obtained using a simple cubic lattice approximation with randomly distributed guest molecules. We show that while differences in host-based processes such as singlet diffusion are observed, overall, the results on the fate of the excitons are in good agreement for the two morphology types, particularly for guest-based processes at low guest concentrations where guest clustering is limited.
Compact tunable YIG-based RF resonators
Authors: Costa José Diogo , Figeys Bruno , Sun Xiao , Van Hoovels Nele , Tilmans Harrie A. C. , Ciubotaru Florin , Adelmann Christoph
Published: April 2021

We report on the design, fabrication, and characterization of compact tunable yttrium iron garnet (YIG)-based RF resonators based on μm-sized spin-wave cavities. Inductive antennas with both ladder and meander configurations were used as transducers between spin waves and RF signals. The excitation of ferromagnetic resonance and standing spin waves in the YIG cavities led to sharp resonances with quality factors up to 350. The observed spectra were in excellent agreement with a model based on the spin-wave dispersion relations in YIG, showing a high magnetic field tunability of about 29 MHz/mT.
Spontaneous electron emission vs dissociation in internally hot silver dimer anions
Authors: Jasik P. , Franz J. , Kędziera D. , Kilich T. , Kozicki J. , Sienkiewicz J. E.
Published: April 2021

Referring to a recent experiment, we theoretically study the process of a two-channel decay of the diatomic silver anion (Ag2−), namely, the spontaneous electron ejection giving Ag2 + e− and the dissociation leading to Ag− + Ag. The ground state potential energy curves of the silver molecules of diatomic neutral and negative ions were calculated using proper pseudo-potentials and atomic basis sets. We also estimated the non-adiabatic electronic coupling between the ground state of Ag2− and the ground state of Ag2 + e−, which, in turn, allowed us to estimate the minimal and mean values of the electron autodetachment lifetimes. The relative energies of the rovibrational levels allow the description of the spontaneous electron emission process, while the description of the rotational dissociation is treated with the quantum dynamics method as well as time-independent methods. The results of our calculations are verified by comparison with the experimental data.
A full configuration interaction quantum Monte Carlo study of ScO, TiO, and VO molecules
Authors: Jiang Tonghuan , Chen Yilin , Bogdanov Nikolay A. , Wang Enge , Alavi Ali , Chen Ji
Published: April 2021

Accurate ab initio calculations of 3d transition metal monoxide molecules have attracted extensive attention because of their relevance in physical and chemical science as well as theoretical challenges in treating strong electron correlation. Meanwhile, recent years have witnessed the rapid development of the full configuration interaction quantum Monte Carlo (FCIQMC) method to tackle electron correlation. In this study, we carry out FCIQMC simulations to ScO, TiO, and VO molecules and obtain accurate descriptions of 13 low-lying electronic states (ScO 2Σ+, 2Δ, 2Π; TiO 3Δ, 1Δ, 1Σ+, 3Π, 3Φ; VO 4Σ−, 4Φ, 4Π, 2Γ, 2Δ), including states that have significant multi-configurational character. The FCIQMC results are used to assess the performance of several other wave function theory and density functional theory methods. Our study highlights the challenging nature of the electronic structure of transition metal oxides and demonstrates FCIQMC as a promising technique going forward to treat more complex transition metal oxide molecules and materials.
Role of energy-band offset in photo-electrochemical etching mechanism of p-GaN heterostructures
Authors: Fariza Aqdas , Ji Xiaoli , Gao Yaqi , Ran Junxue , Wang Junxi , Wei Tongbo
Published: April 2021

For developing p-GaN gate-based enhancement-mode AlGaN/GaN high-electron-mobility transistors, the removal of the p-GaN layer around the gate region is demonstrated by photo-electrochemical etching. The etching behavior of p-GaN/AlGaN/GaN heterostructures along with p-GaN/u-GaN reference samples is investigated in acidic H2SO4/H3PO4 electrolyte solution. The strong oxidant sulfate radical SO4−∗ formed by H2SO4 stimulates the etching process by either extracting excess electrons from the valence band or providing supplementary holes in the valence band. By optimizing the etching parameters, an average etching rate of 0.27 nm/min with a surface roughness of 2.3 nm is achieved for removing p-GaN from the AlGaN/GaN structure. The etching dynamics of the heterostructure are attributed to the valence-band offset ΔEv caused by band discontinuity at the p-GaN/AlGaN interface. Under positive anodic bias, the etching process is also controlled by local charge transport between p-GaN and the two-dimensional electron gas channel due to a reduced barrier height.
An integrated microfluidic platform to fabricate single-micrometer asymmetric giant unilamellar vesicles (GUVs) using dielectrophoretic separation of microemulsions
Authors: Maktabi Sepehr , Malmstadt Noah , Schertzer Jeffrey W. , Chiarot Paul R.
Published: April 2021

We present a microfluidic technique that generates asymmetric giant unilamellar vesicles (GUVs) in the size range of 2–14 μm. In our method, we (i) create water-in-oil emulsions as the precursors to build synthetic vesicles, (ii) deflect the emulsions across two oil streams containing different phospholipids at high throughput to establish an asymmetric architecture in the lipid bilayer membranes, and (iii) direct the water-in-oil emulsions across the oil–water interface of an oscillating oil jet in a co-flowing confined geometry to encapsulate the inner aqueous phase inside a lipid bilayer and complete the fabrication of GUVs. In the first step, we utilize a flow-focusing geometry with precisely controlled pneumatic pressures to form monodisperse water-in-oil emulsions. We observed different regimes in forming water-in-oil multiphase flows by changing the applied pressures and discovered a hysteretic behavior in jet breakup and droplet generation. In the second step of GUV fabrication, an oil stream containing phospholipids carries the emulsions into a separation region where we steer the emulsions across two parallel oil streams using active dielectrophoretic and pinched-flow fractionation separations. We explore the effect of applied DC voltage magnitude and carrier oil stream flow rate on the separation efficiency. We develop an image processing code that measures the degree of mixing between the two oil streams as the water-in-oil emulsions travel across them under dielectrophoretic steering to find the ideal operational conditions. Finally, we utilize an oscillating co-flowing jet to complete the formation of asymmetric giant unilamellar vesicles and transfer them to an aqueous phase. We investigate the effect of flow rates on properties of the co-flowing jet oscillating in the whipping mode (i.e., wavelength and amplitude) and define the phase diagram for the oil-in-water jet. Assays used to probe the lipid bilayer membrane of fabricated GUVs showed that membranes were unilamellar, minimal residual oil remained trapped between the two lipid leaflets, and 83% asymmetry was achieved across the lipid bilayers of GUVs.
Site-selective dynamics of azidolysozyme
Authors: Salehi Seyedeh Maryam , Meuwly Markus
Published: April 2021

The spectroscopic response of and structural dynamics around all azido-modified alanine residues (AlaN3) in lysozyme are characterized. It is found that AlaN3 is a positionally sensitive probe for the local dynamics, covering a frequency range of ∼15 cm−1 for the center frequency of the line shape. This is consistent with findings from selective replacements of amino acids in PDZ2, which reported a frequency span of ∼10 cm−1 for replacements of Val, Ala, or Glu by azidohomoalanine. For the frequency fluctuation correlation functions, the long-time decay constants τ2 range from ∼1 to ∼10 ps, which compares with experimentally measured correlation times of 3 ps. Attaching azide to alanine residues can yield dynamics that decays to zero on the few ps time scale (i.e., static component Δ0 ∼ 0 ps−1) or to a remaining, static contribution of ∼0.5 ps−1 (corresponding to 2.5 cm−1), depending on the local environment on the 10 ps time scale. The magnitude of the static component correlates qualitatively with the degree of hydration of the spectroscopic probe. Although attaching azide to alanine residues is found to be structurally minimally invasive with respect to the overall protein structure, analysis of the local hydrophobicity indicates that the hydration around the modification site differs for modified and unmodified alanine residues, respectively.
Fast skeletal myosin-binding protein-C regulates fast skeletal muscle contraction
Authors: Song Taejeong , McNamara James W. , Ma Weikang , Landim-Vieira Maicon , Lee Kyoung Hwan , Martin Lisa A. , Heiny Judith A. , Lorenz John N. , Craig Roger , Pinto Jose Renato , Irving Thomas , Sadayappan Sakthivel
Published: April 2021

Significance

Myosin-binding protein-C (MyBP-C) is a thick filament regulatory protein found exclusively in the C-zone of the A-band in the sarcomeres of vertebrate striated muscle. Cardiac, slow skeletal, and fast skeletal MyBP-C (fMyBP-C) paralogs perform different functions. All three paralogs share similar protein structures but likely differ substantially in terms of expression and function, which may serve the distinct physiologies of fast and slow muscle fibers. However, the functional role of fMyBP-C in fast skeletal muscle is completely unknown. Genetic mutations in human fMyBP-C lead to skeletal myopathies. In this study, we used knockout mice to define the molecular basis for fMyBP-C paralog diversity. We demonstrate that fMyBP-C modulates the speed and force of fast skeletal muscle contraction.
Circulating mitochondrialN-formyl peptides contribute to secondary nosocomial infection in patients with septic shock
Authors: Kwon Woon Yong , Suh Gil Joon , Jung Yoon Sun , Park Seung Min , Oh Subi , Kim Sung Hee , Lee A. Rum , Kim Jeong Yeon , Kim Hayoung , Kim Kyung Ah , Kim Young , Kim Byoung Choul , Kim Taegyun , Kim Kyung Su , Itagaki Kiyoshi , Hauser Carl J.
Published: April 2021

Significance

Septic shock commonly leads to multiorgan injury both directly via tissue inflammation and secondarily via hypoperfusion, but both can result in mitochondrialN-formyl peptide (mtFP) release into the circulation. However, no studies have evaluated the role of circulating mtFPs during septic shock. We found that a relatively high plasma nicotinamide adenine dinucleotide dehydrogenase subunit-6 (the most potent human mtFP) level was independently associated with the development of secondary infection in patients with septic shock and that the increased susceptibility to secondary infection is partly attributed to the suppression of polymorphonuclear leukocyte (PMN) chemotaxis by mtFP occupancy of formyl peptide receptor-1. Incorporation of these findings into therapeutic strategies may improve clinical outcomes in septic shock patients by preventing PMN chemotactic anergy.
Viral packaging ATPases utilize a glutamate switch to couple ATPase activity and DNA translocation
Authors: Pajak Joshua , Atz Rockney , Hilbert Brendan J. , Morais Marc C. , Kelch Brian A. , Jardine Paul J. , Arya Gaurav
Published: April 2021

Significance

Many biological processes are performed by ring-shaped molecular motors that harvest energy from ATP hydrolysis to move DNA, RNA, or protein substrate through their central pores. However, it is not clear how these proteins couple their physical movement to the chemical steps of ATP hydrolysis. Here, we derive the molecular mechanism by which viral DNA packaging motors couple ATP binding to DNA gripping and ATP hydrolysis to DNA release. We first predict the coupling pathway computationally with molecular dynamics simulations and then validate our predictions experimentally with structural and functional measurements. The mechanism derived and presented here could be broadly applicable to all ring ATPase motors.
Achatina fulica (giant African land snail).
Authors: Vogler Roberto E , Beltramino Ariel A
Published: April 2021

The giant African land snail A. fulica is a fast-growing polyphagous plant pest that has been introduced from its native range in East Africa to many parts of the world as a commercial food source (for humans, fish and livestock) and as a novelty pet. It easily becomes attached to any means of transport or machinery at any developmental stage, is able to go into a state of aestivation in cooler conditions and so is readily transportable over distances. Once escaped it has managed to establish itself and reproduce prodigiously in tropical and some temperate locations. As a result, A. fulica has been classified as one of the world's top 100 invasive alien species by The World Conservation Union, IUCN (ISSG, 2003).
ICOS signaling limits regulatory T cell accumulation and function in visceral adipose tissue
Authors: Mittelsteadt Kristen L. , Hayes Erika T. , Campbell Daniel J.
Published: April 2021

A unique population of Foxp3+ regulatory T cells (TRs) resides in visceral adipose tissue (VAT) that regulates adipose inflammation and helps preserve insulin sensitivity. Inducible T cell co-stimulator (ICOS) is highly expressed on effector (e)TRs that migrate to nonlymphoid tissues, and contributes to their maintenance and function in models of autoimmunity. In this study, we report an unexpected cell-intrinsic role for ICOS expression and downstream phosphoinositide 3-kinase (PI3K) signaling in limiting the abundance, VAT-associated phenotype, and function of TRs specifically in VAT. Icos−/− mice and mice expressing a knock-in form of ICOS that cannot activate PI3K had increased VAT-TR abundance and elevated expression of canonical VAT-TR markers. Loss of ICOS signaling facilitated enhanced accumulation of TRs to VAT associated with elevated CCR3 expression, and resulted in reduced adipose inflammation and heightened insulin sensitivity in the context of a high-fat diet. Thus, we have uncovered a new and surprising molecular pathway that regulates VAT-TR accumulation and function.
Graviton backreaction on the local cosmological expansion in slow-roll inflation
Authors: Lima William C C
Published: April 2021

We compute the graviton one-loop correction to the expectation value of the local expansion rate in slow-roll inflation, with both slow-roll parameters finite. The calculation is based on a recent method to explicitly construct gauge-invariant observables in perturbative quantum gravity at all orders in perturbation theory, and it is particularly suited in cases of highly-symmetrical space-time backgrounds. Our analysis adds to recent calculations of that correction in de Sitter space-time and in single-field inflation with constant deceleration. In the former case a vanishing one-loop correction was found, while in the latter the quantum backreaction produces a secular effect that accelerates the expansion. The quantum correction we describe here produces a finite secular effect that can either accelerated or decelerate the background expansion, depending on the value of the slow-roll parameters.
Graded magnetic materials
Authors: Fallarino Lorenzo , Kirby Brian J , Fullerton Eric E
Published: April 2021

Graded magnetic materials represent a promising new avenue in modern material science from both fundamental and application points of view. Over the course of the last few years, remarkable results have been obtained in (epitaxial) heterostructures based on thin alloy films featuring diverse compositional depth profiles. As a result of the precise tailoring of such profiles, the exchange coupling, and the corresponding effective or local Curie temperatures can be controlled over tens of nm with an excellent precision. This topical review article reports the most recent advances in this emerging research field. Several aspects are covered, but the primary focus lies in the study of compositional gradients being transferred into depth dependent magnetic states in ferromagnets, while also reviewing other experimental attempts to create exchange graded films and materials in general. We account for the remarkable progress achieved in each sample and composition geometry by reporting the recent developments and by discussing the research highlights obtained by several groups. Finally, we conclude the review article with an outlook on future challenges in this field.
Development of detailed pediatric eye models for lens dose calculations
Authors: Han Haegin , Yeom Yeon Soo , Nguyen Thang Tat , Choi Chansoo , Shin Bangho , Moon Sungho , Ha Sangseok , Son Gahee , Augusteyn Robert , Kim Chan Hyeong
Published: April 2021

The International Commission on Radiological Protection (ICRP) recently reduced the dose limit for the eye lens for occupational exposure from 150 mSv yr−1 to 20 mSv yr−1, as averaged over defined periods of five years, with no annual dose in a single year exceeding 50 mSv, emphasizing the importance of the accurate estimation of lens dose. In the present study, for more accurate lens dosimetry, detailed eye models were developed for children and adolescents (newborns and 1, 5, 10, and 15 year olds), which were then incorporated into the pediatric mesh-type reference computational phantoms (MRCPs) and used to calculate lens dose coefficients (DCs) for photon and electron exposures. Finally, the calculated values were compared with those calculated with the adult MRCPs in order to determine the age dependence of the lens DCs. For photon exposures, the lens DCs of the pediatric MRCPs showed some sizable differences from those of the adult MRCPs at very low energies (10 and 15 keV), but the differences were all less than 35%, except for the posterior-anterior irradiation geometry, for which the lens dose is not of primary concern. For electron exposures, much larger differences were found. For the anterior-posterior (AP) and isotropic irradiation geometries, the largest differences between the lens DCs of the pediatric and adult phantoms were found in the energy range of 0.6–1 MeV, where the newborn lens DCs were larger by up to a factor of ∼5 than the adult. The lens DCs of the present study, which were calculated for the radiosensitive region of the lens, also were compared with those for the entire lens in the AP irradiation geometry. Our results showed that the DCs of the entire lens were similar to those of the radiosensitive region for 0.02–2 MeV photons and >2 MeV electrons, but that for the other energy ranges, significant differences were noticeable, i.e. 10%–40% for photons and up to a factor of ∼5 for electrons.
On the uncertainty of boundary-layer parameters from Ensemble PTV data
Authors: Castellanos R , Sanmiguel Vila C , Güemes A , Discetti S
Published: April 2021

The recent advancements in high-resolution turbulence-statistics computation from ensemble particle tracking velocimetry (EPTV) data are now opening new possibilities in turbulent-flow characterisation. Measurements of full-field boundary layer profiles with a fine resolution close to the wall and up to the freestream with one single imaging setup are now feasible, thus paving the way to direct characterisation of turbulent-boundary-layer (TBL) parameters with composite-profile formulations. In this work, we build a framework for the estimation of the uncertainty of EPTV in performing this task. The effect of systematic errors due to finite spatial resolution and of random error due to convergence are investigated under different window size. Then we introduce random errors to simulate the effects on convergence issues on the velocity profile and, consequently, on the estimation of turbulent-boundary-layer parameters. The statistical dispersion of the estimated parameters provides an estimation of the uncertainty range. We validate with experimental data this flexible tool to estimate a priori the expected uncertainty level of the most relevant turbulent-boundary-layer parameters in zero-pressure-gradient TBL, being the method based on existing profiles from high-fidelity simulation or from analytical composite-profile formulations when such data are not available.
FeCo nanoparticles as antibacterial agents with improved response in magnetic field: an insight into the associated toxicity mechanism
Authors: Moditma  , Singh Priyanka , Sharma Raksha , Verma Anita K , Annapoorni S
Published: April 2021

The emergence of multi-drug resistant bacterial infections has resulted in increased interest in the development of alternative systems which can sensitize bacteria to overcome resistance. In an attempt to contribute to the existing literature of potential antibacterial agents, we present here, a first report of the antibacterial potential of FeCo nanoparticles, both as stand-alone devices and in presence of magnetic field, against the bacterial strains of S. aureus and E. coli. A relatively simple polyol process was employed for nanoparticle synthesis. Formation of FeCo alloy in the desired BCC phase was confirmed by x-ray diffraction with a high saturation magnetization (M
s ∼ 180 Am2kg−1). Uniformly sized spherical structures with sharp edges were obtained. Solution stability was confirmed by the zeta potential value of −27.8 mV. Dose dependent bacterial growth inhibition was observed, the corresponding linear correlation coefficients being, R
2 = 0.74 for S. aureus and R
2 = 0.76 for E. coli. Minimum inhibitory concentration was accordingly ascertained to be >1024 μg ml−1 for both. Bacterial growth curves have been examined upon concomitant application of external magnetic field of varying intensities and revealed considerable enhancement in the antibacterial response upto 64% in a field of 100 mT. An effort has been made to understand the bacterial inhibitory mechanism by relating with the chemical and physical properties of the nanoparticles. The ease of field assisted targeting and retrieval of these highly magnetic, antibacterial nano-devices, with considerably improved response with magnetic fields, make them promising for several medical and environment remediation technologies.
Ultra-high-frequency (UHF) surface-acoustic-wave (SAW) microfluidics and biosensors
Authors: Agostini Matteo , Cecchini Marco
Published: April 2021

Surface acoustic waves (SAWs) have the potential to become the basis for a wide gamut of lab-on-a-chips (LoCs). These mechanical waves are among the most promising physics that can be exploited for fulfilling all the requirements of commercially appealing devices that aim to replace–or help–laboratory facilities. These requirements are low processing cost of the devices, scalable production, controllable physics, large flexibility of tasks to perform, easy device miniaturization. To date, SAWs are among the small set of technologies able to both manipulate and analyze biological liquids with high performance. Therefore, they address the main needs of microfluidics and biosensing. To this purpose, the use of high-frequency SAWs is key. In the ultra-high-frequency regime (UHF, 300 MHz—3 GHz) SAWs exhibit large sensitivities to molecule adsorption and unparalleled fluid manipulation capabilities, together with overall device miniaturization. The UHF-SAW technology is expected to be the realm for the development of complex, reliable, fully automated, high-performance LoCs. In this review, we present the most recent works on UHF-SAWs for microfluidics and biosensing, with a particular focus on the LoC application. We derive the relevant scale laws, useful formulas, fabrication guidelines, current limitations of the technology, and future developments.
Boosting photoresposive ability of WO3–Bi2O3 nanocomposite rods via annealing-induced intrinsic precipitation of nanosized Bi particles
Authors: Liang Yuan-Chang , Yang Ho-Chung
Published: April 2021

In this study, Bi-particle-functionalized tungsten trioxide–bismuth oxide (WO3–Bi2O3) composite nanorods were prepared by integrating sputtering and hydrothermal syntheses with an appropriate postannealing procedure to induce Bi particle precipitation. Unlike other routes in which metal particle decoration is achieved externally, in this study, photoresponsive one-dimensional WO3–Bi2O3 composite nanorods were decorated with Bi particles by using the internal precipitation method. Structural analysis revealed that the Bi-metal-particle-functionalized WO3–Bi2O3 composite nanorods with particle size ranging from 5 to 10 nm were formed through hydrogen gas annealing at an optimal annealing temperature of 350 °C. Compared with the pristine WO3 nanorod template, the Bi–WO3–Bi2O3 composite nanorods exhibited higher photoresponsive performance, substantial photogenerated charge transfer ability, and efficient separation of photogenerated electron–hole pairs. The study results indicated that the Bi–WO3–Bi2O3 composite nanorods had superior decontamination ability and excellent stability toward RhB dye as compared with pristine WO3. Moreover, the photogenerated charge separation and migration efficiencies of the WO3–Bi2O3 nanorods could be tuned through appropriate reduction of the surface oxide layer; this is a promising approach to designing WO3–Bi2O3 nanorods with high photoactive performance.
Oscillation frequencies of a double pendulum
Authors: Cross Rod
Published: April 2021

The oscillation frequencies of a double pendulum are derived by extending the usual calculation for a single pendulum. Experimental results are presented as supplementary videos.
Simulating the flight of an oval football
Authors: Cross Rod
Published: April 2021

The flight of a spinning rugby ball is difficult to describe mathematically but easy to observe experimentally. The flight can be simulated by dropping an egg into a water tank and observing or filming the outcome. Differences between a spinning and a non-spinning wooden egg are presented as supplementary videos.
Mass segmentation for whole mammograms via attentive multi-task learning framework
Authors: Hou Xuan , Bai Yunpeng , Xie Yefan , Li Ying
Published: April 2021

Mass segmentation in the mammogram is a necessary and challenging task in the computer-aided diagnosis of breast cancer. Most of the existing methods tend to segment the mass by manually or automatically extracting mass-centered image patches. However, manual patch extraction is time-consuming, wheras automatic patch extraction can introduce errors that will affect the performance of subsequent segmentation. In order to improve the efficiency of mass segmentation and reduce segmentation errors, we proposed a novel mass segmentation method based on an attentive multi-task learning network (MTLNet), which is an end-to-end model to accurately segment mass in the whole mammogram directly, without the need for extraction in advance with the center of mass image patch. In MTLNet, we applied group convolution to the feature extraction network, which not only reduced the redundancy of the network but also improved the capacity of feature learning. Secondly, an attention mechanism is added to the backbone to highlight the feature channels that contain rich information. Eventually, the multi-task learning framework is employed in the model, which reduces the risk of model overfitting and enables the model not only to segment the mass but also to classify and locate the mass. We used five-fold cross validation to evaluate the performance of the proposed method under detection and segmentation tasks respectively on the two public mammographic datasets INbreast and CBIS-DDSM, and our method achieved a Dice index of 0.826 on INbreast and 0.863 on CBIS-DDSM.
PET-ABC: fully Bayesian likelihood-free inference for kinetic models
Authors: Fan Yanan , Emvalomenos Gaelle , Grazian Clara , Meikle Steven R
Published: April 2021

Aims. We describe an intuitive, easy to use method called PET-ABC that enables full Bayesian statistical inference from single subject dynamic PET data. The performance of PET-ABC was compared with weighted non-linear least squares (WNLS) in terms of reliability of kinetic parameter estimation and statistical power for model selection. Methods. Dynamic PET data based on 1-tissue and 2-tissue compartmental models were simulated with 2 noise models and 3 noise levels. PET-ABC was used to evaluate the reliability of parameter estimates under each condition. It was also used to perform model selection for a simulated noisy dataset composed of a mixture of 1- and 2-tissue compartment kinetics. Finally, PET-ABC was used to analyze a non-steady state dynamic [11C] raclopride study performed on a fully conscious rat administered either 2 mg.kg−1 amphetamine or saline 20 min after tracer injection. Results. PET-ABC yielded posterior point estimates for model parameters with smaller variance than WNLS, as well as probability density functions indicating confidence intervals for those estimates. It successfully identified the superiority of a 2-tissue compartment model to fit the simulated mixed model data. For the drug challenge study, the post observation probability of striatal displacement of the PET signal was 0.9 for amphetamine and approximately 0 for saline, indicating a high probability of amphetamine-induced endogenous dopamine release in the striatum. PET-ABC also demonstrated superior statistical power to WNLS (0.87 versus 0.09) for selecting the correct model in a simulated ligand displacement study. Conclusions. PET-ABC is a simple and intuitive method that provides complete Bayesian statistical analysis of single subject dynamic PET data, including the extent to which model parameter estimates and model choice are supported by the data. Software for PET-ABC is freely available as part of the PETabc package https://github.com/cgrazian/PETabc.
Axial-SpineGAN: simultaneous segmentation and diagnosis of multiple spinal structures on axial magnetic resonance imaging images
Authors: Gong Hao , Liu Jianhua , Li Shuo , Chen Bo
Published: April 2021

Providing a simultaneous segmentation and diagnosis of the spinal structures on axial magnetic resonance imaging (MRI) images has significant value for subsequent pathological analyses and clinical treatments. However, this task remains challenging, owing to the significant structural diversity, subtle differences between normal and abnormal structures, implicit borders, and insufficient training data. In this study, we propose an innovative network framework called ‘Axial-SpineGAN’ comprising a generator, discriminator, and diagnostor, aiming to address the above challenges, and to achieve simultaneous segmentation and disease diagnosis for discs, neural foramens, thecal sacs, and posterior arches on axial MRI images. The generator employs an enhancing feature fusion module to generate discriminative features, i.e. to address the challenges regarding the significant structural diversity and subtle differences between normal and abnormal structures. An enhancing border alignment module is employed to obtain an accurate pixel classification of the implicit borders. The discriminator employs an adversarial learning module to effectively strengthen the higher-order spatial consistency, and to avoid overfitting owing to insufficient training data. The diagnostor employs an automated diagnosis module to provide automated recognition of spinal diseases. Extensive experiments demonstrate that these modules have positive effects on improving the segmentation and diagnosis accuracies. Additionally, the results indicate that Axial-SpineGAN has the highest Dice similarity coefficient (94.9% ± 1.8%) in terms of the segmentation accuracy and highest accuracy rate (93.9% ± 2.6%) in terms of the diagnosis accuracy, thereby outperforming existing state-of-the-art methods. Therefore, our proposed Axial-SpineGAN is effective and potential as a clinical tool for providing an automated segmentation and disease diagnosis for multiple spinal structures on MRI images.
Validation of a 4D-MRI guided liver stereotactic body radiation therapy strategy for implementation on the MR-linac
Authors: van de Lindt Tessa N , Fast Martin F , van den Wollenberg Wouter , Kaas Jochem , Betgen Anja , Nowee Marlies E , Jansen Edwin PM , Schneider Christoph , van der Heide Uulke A , Sonke Jan-Jakob
Published: April 2021

Purpose. Accurate tumor localization for image-guided liver stereotactic body radiation therapy (SBRT) is challenging due to respiratory motion and poor tumor visibility on conventional x-ray based images. Novel integrated MRI and radiotherapy systems enable direct in-room tumor visualization, potentially increasing treatment accuracy. As these systems currently do not provide a 4D image-guided radiotherapy strategy, we developed a 4D-MRI guided liver SBRT workflow and validated all steps for implementation on the Unity MR-linac. Materials and Methods. The proposed workflow consists of five steps: (1) acquisition of a daily 4D-MRI scan, (2) 4D-MRI to mid-position planning-CT rigid tumor registration, (3) calculation of daily tumor midP misalignment, (4) plan adaptation using adapt-to-position (ATP) with segment-weights optimization and (5) adapted plan delivery. The workflow was first validated in a motion phantom, performing regular motion at different baselines (±5 to ±10 mm) and patient-derived respiratory signals with varying degrees of irregularity. 4D-MRI derived respiratory signals and 4D-MRI to planning CT registrations were compared to the phantom input, and gamma and dose-area-histogram analyses were performed on the delivered dose distributions on film. Additionally, 4D-MRI to CT registration performance was evaluated in patient images using the full-circle method (transitivity analysis). Plan adaption was further analyzed in-silico by creating adapted treatment plans for 15 patients with oligometastatic liver disease. Results. Phantom trajectories could be reliably extracted from 4D-MRI scans and 4D-MRI to CT registration showed submillimeter accuracy. The DAH-analysis demonstrated excellent coverage of the dose evaluation structures GTV and GTVTD. The median daily rigid 4D-MRI to midP-CT registration precision in patient images was <2 mm. The ATP strategy restored the target dose without increased exposure to the OARs and plan quality was independent from 3D shift distance in the range of 1–26 mm. Conclusions. The proposed 4D-MRI guided strategy showed excellent performance in all workflow tests in preparation of the clinical introduction on the Unity MR-linac.
Disruption prediction and model analysis using LightGBM on J-TEXT and HL-2A
Authors: Zhong Y , Zheng W , Chen Z Y , Xia F , Yu L M , Wu Q Q , Ai X K , Shen C S , Yang Z Y , Yan W , Ding Y H , Liang Y F , Chen Z P , Tong R H , Bai W , Fang J G , Li F
Published: April 2021

Using machine learning (ML) techniques to develop disruption predictors is an effective way to avoid or mitigate the disruption in a large-scale tokamak. The recent ML-based disruption predictors have made great progress regarding accuracy, but most of them have not achieved acceptable cross-machine performance. Before we develop a cross-machine predictor, it is very important to investigate the method of developing a cross-tokamak ML-based disruption prediction model. To ascertain the elements which impact the model’s performance and achieve a deep understanding of the predictor, multiple models are trained using data from two different tokamaks, J-TEXT and HL-2A, based on an implementation of the gradient-boosted decision trees algorithm called LightGBM, which can provide detailed information about the model and input features. The predictor models are not only built and tested for performance, but also analyzed from a feature importance perspective as well as for model performance variation. The relative feature importance ranking of two tokamaks is caused by differences in disruption types between different tokamaks. The result of two models with seven inputs showed that common diagnostics is very important in building a cross-machine predictor. This provided a strategy for selecting diagnostics and shots data for developing cross-machine predictors.
Quantum repeaters in space
Authors: Liorni Carlo , Kampermann Hermann , Bruß Dagmar
Published: April 2021

Long-distance entanglement is a very precious resource, but its distribution is very difficult due to the exponential losses of light in optical fibres. A possible solution consists in the use of quantum repeaters, based on entanglement swapping (ES) or quantum error correction. Alternatively, satellite-based free-space optical links can be exploited, achieving better loss-distance scaling. We propose to combine these two ingredients, quantum repeaters and satellite-based links, into a scheme that allows to achieve entanglement distribution over global distances with a small number of intermediate untrusted nodes. The entanglement sources, placed on satellites, send quantum states encoded in photons towards orbiting quantum repeater stations, where ES is performed. The performance of this repeater chain is assessed in terms of the secret key rate achievable by the BBM92 cryptographic protocol. We perform a comparison with other repeater chain architectures and show that our scheme, even though more technically demanding, is superior in many situations of interest. Finally, we analyse strengths and weaknesses of the proposed scheme and discuss exemplary orbital configurations. The integration of satellite-based links with ground repeater networks can be envisaged to represent the backbone of the future quantum internet.
Collisionless damping of nonplanar dust acoustic waves due to dust charge fluctuation in nonextensive polarized plasma
Authors: Gill Tarsem S , Bansal Sona
Published: April 2021

A rigorous theoretical investigation has been made of the cylindrical/spherical dust acoustic waves in collisionless dusty plasma with variable charges under the influence of polarization force by reductive perturbation method. It is shown that the collisionless damping due to dust charge fluctuation causes the dust acoustic wave propagation to be described by the nonplanar damped Korteweg–de Vries equation. By use of weighted residual method, a progressive wave solution to nonplanar damped KdV equation is presented for the first time. It is shown that dust charge fluctuation produce damping which is responsible for wave attenuation. The solution shows that as one goes towards the axis of the cylinder or centre of the sphere, the wave attenuates faster and the effects are shown in some 2D figures. Within a small amplitude limit, the influence of dust charge fluctuation, polarisation power, nonextensivity and ion temperature on the time evolution of dust acoustic solitons is also demonstrated. In laboratory experiments and space regions, findings obtained here may shed light on the salient characteristics of DA waves.