bluuebunny/crossref_metadata_2025 huggingface dataset:
Structurally photo-active metal–organic frameworks: Incorporation methods, response tuning, and potential applications
Authors: Shepherd Nicholas D. , D'Alessandro Deanna M.
Published: March 2021

Metal–organic frameworks (MOFs) are an important family of materials due to the properties that make them well suited to a range of applications. This includes structurally photo-active MOFs, which have properties that can be efficiently modulated through controlled light irradiation, making them ideal due to the cost-effectiveness and noninvasive nature of this stimulus. The incorporation of structurally photo-active functional groups into MOFs has occurred through either guest inclusion, as pendant moieties, or as part of a ligand's backbone. While initial studies into the incorporation of these groups focused on prominent photo-switches such as azobenzenes, the literature has expanded to include other classes described in the wider photo-switch literature, most notably spiropyrans (SPs). The incorporation of alternative photo-switching classes has currently benefited the field through tuning the light responsive wavelength. Initial inquiries demonstrated suitable function in gas sorption applications where irradiation could be exploited for inducing adsorption or desorption. Furthermore, the potential applications explored in the literature have also recently expanded to include inquiries into other commercial functions, such as desalination [R. Ou et al., Nat. Sustain. 3, 1052–1058 (2020)], photo-lithography [H. A. Schwartz et al., Inorg. Chem. 56(21), 13100–13110 (2017)], and drug capture/release [X. Meng et al., Sci. Adv. 2(8), 2–8 (2016)].
Development of a narrow stopband filter for spectroscopic fast ion deuterium-alpha measurements
Authors: Lin D. J. , Muscatello C. M. , Heidbrink W. W.
Published: March 2021

A new technique to attenuate the unshifted deuterium Balmer-alpha (D-alpha) emission is developed and tested for the fast ion D-alpha (FIDA) diagnostic. The unshifted D-alpha emission, at λ = 656.1 nm, is around three orders of magnitude higher than the desired FIDA emission. Blocking the strong emission feature is essential to prevent blooming and light smearing on the CCD chip and scattered light contamination. The new method is a notch filter approach that utilizes the reflection from ultra-narrow bandpass filters to block the saturating signal before it enters the spectrometer. Collimated light from the fibers is reflected off the filter at a 15° angle of incidence. Measurements show that a center wavelength transmission of 0.006 and a blocking full width at half maximum of ∼1 nm are achieved by using a 200 μm fiber and a 20 mm focal length collimator with two filters.
Impact response of a tungsten heavy alloy over 23–1100 °C temperature range
Authors: Zaretsky E. B. , Frage N. , Ratzker B. , Kalabukhov S. , Mayseless M.
Published: March 2021

Impact response of a tungsten heavy alloy (WHA) prepared by liquid phase sintering of tungsten powder (∼80 vol. %) with an Ni–Co–Fe (3.50–1.25–1.0 weight ratio) binder was studied over a 23–1100 °C temperature range in a series of planar impact tests accompanied by continuous monitoring of the velocity of the WHA sample rear surface. The temperature dependence of the proof stress Y0.1(T) was found based on the 1D numerical simulations of the performed impact tests using a modified Steinberg–Cohran–Guinan constitutive model, and the temperature dependencies of the density ρ0(T) and longitudinal cl(T) and bulk cb(T) speeds of sound were found using rule of mixtures. The bulk speed of sound cb(T) was also used in determination of the temperature dependence of the spall strength σsp(T) of the alloy based on the experimentally recorded velocity pull-backs Δupb. The strong decrease of both Y0.1(T) and σsp(T) with temperature (Y0.1 decreases almost sixfold between 23 and 1100 °C) allows one to assume that the tensile (spall) fracture of the alloy is controlled by the strength of its matrix.
Eccentric disks falling in water
Authors: Zhou Xinping , Yuan Shuo , Zhang Gang
Published: March 2021

The freely falling of solid bodies in viscous liquids is an interesting issue concerned with many hydrodynamics and engineering problems. The eccentricity of the solid bodies may lead to new dynamic behaviors and complex paths of falling. Eccentric annular disks with holes covered by transparent tapes are used to study the effect of eccentricity on the descent flight. This paper experimentally investigates the falling regimes of the eccentric disks in water with Reynolds number between 4000 and 21 000 and classifies the descent modes into three types, i.e., the fluttering, chaotic, and tumbling motions, the transition motion, and the new stable descending motion. Finally, we map out the three descent modes of eccentric disks in a two-dimensional phase space of eccentricity e and dimensionless moment of inertia I*. It is found that eccentricity is a significant parameter when describing the descent modes of eccentric disks. Enough large eccentricity stabilizes freely falling disks, while small eccentricity (e < 0.06) leads to the rotation of disk in an arc in the x-y plane accompanied by chaotic and tumbling motions or asymmetric zigzag motion. The descent modes are mainly dependent on e for I* higher than 0.02, and dependent on both e and I* for I* lower than 0.02.
Selective spin transmission through a driven quantum system: A new prescription
Authors: Ganguly Sudin , Maiti Santanu K.
Published: March 2021

Several proposals are available to get selective spin transmission through different nano-junctions and in all the cases the regulation is done either by applying a magnetic field or by tuning spin–orbit (SO) coupling. In the present work, we explore a separate scheme where the spin-dependent transport is regulated externally by irradiating a quantum ring that bridges the contact electrodes. This is a new proposal of generating spin selective transmission through a nano-junction, to the best of our knowledge. A high degree of spin polarization along with its phase alteration can be achieved by suitably adjusting the irradiation, circumventing the regulation of magnetic field and/or SO coupling. The effect of irradiation is included through the well-known Floquet-Bloch ansatz, where all the spin-dependent transport phenomena are worked out using Green’s function formalism following the Landauer–Büttiker prescription within a tight-binding framework. Precise dependencies of light irradiation, SO coupling, magnetic flux threaded by the ring, interface sensitivity, system temperature, and impurities on spin polarization are critically investigated. Our analysis may give a new platform for spin selective electron transmission and make it applicable to other complex nano-structured materials also. We strongly believe that the present proposal can be examined in a suitable laboratory.
Natural modes of the two-fluid model of two-phase flow
Authors: Clausse Alejandro , López de Bertodano Martín
Published: March 2021

A physically based method to derive well-posed instances of the two-fluid momentum transport equations from first principles is presented. The basic tools used in this endeavor are the variational principles of field theory, namely, the Hamilton principle and the virtual power principle. The state of the two-fluid flow is represented by the superficial velocity and the drift flux, instead of the average velocities of each fluid. This generates the conservation equations of the two principal motion modes naturally: the global center-of-mass flow and the relative velocity between fluids. Well-posed equations can be obtained by modeling the storage and exchange of kinetic energy in fluctuations structures induced by the interaction between fluids, like wakes and vortexes. In this way, the equations can be regularized without losing in the process the kinetic instabilities responsible for flow-patterns formation and transition. A specific case of vertical air–water flow is analyzed showing the capability of the present model to predict the formation of the slug flow regime as a train of solitons.
Electric-field-driven coexistence of positive and negative electrocaloric effects near room temperature for high-efficiency two-stage cooling
Authors: Shan Dongliang , Cai Yuchen , Lei Chihou , Peng Jinlin , He Ningbo , Pan Kai , Liu Yunya , Li Jiangyu
Published: March 2021

The electrocaloric (EC) effect is promising for the next-generation solid-state refrigeration, yet it is difficult to improve the EC response near room temperature with either the positive electrocaloric (PEC) or negative electrocaloric (NEC) effect alone. In this work, we propose and demonstrate a strategy that achieves the coexistence of PEC and NEC effects near room temperature via electric-field-induced ferroelectric–ferroelectric phase transition in Ba(ZrxTi1−x)O3 solid solutions, while the PEC effect is generally found around paraelectric–ferroelectric transition and the NEC effect is around ferroelectric–antiferroelectric phase boundaries. Utilizing such a coexistence of PEC and NEC effects, we propose a prototype two-stage cooling device, wherein both the EC cooling temperature change and efficiency are higher than its counterpart with only the PEC or NEC effect, offering a new pathway for EC cooling in practical applications near room temperature.
Molecular dynamics simulations vs field-cycling NMR relaxometry: Structural relaxation mechanisms in the glass-former glycerol revisited
Authors: Becher M. , Wohlfromm T. , Rössler E. A. , Vogel M.
Published: March 2021

We combine field-cycling (FC) relaxometry and molecular dynamics (MD) simulations to study the rotational and translational dynamics associated with the glassy slowdown of glycerol. The 1H NMR spin-lattice relaxation rates R1(ω) probed in the FC measurements for different isotope-labelled compounds are computed from the MD trajectories for broad frequency and temperature ranges. We find high correspondence between experiment and simulation. Concerning the rotational motion, we observe that the aliphatic and hydroxyl groups show similar correlation times but different stretching parameters, while the overall reorientation associated with the structural relaxation remains largely isotropic. Additional analysis of the simulation results reveals that transitions between different molecular configurations are slow on the time scale of the structural relaxation at least at sufficiently high temperatures, indicating that glycerol rotates at a rigid entity, but the reorientation is slower for elongated than for compact conformers. The translational contribution to R1(ω) is well described by the force-free hard sphere model. At sufficiently low frequencies, universal square-root laws provide access to the molecular diffusion coefficients. In both experiment and simulation, the time scales of the rotational and translational motions show an unusually large separation, which is at variance with the Stokes–Einstein–Debye relation. To further explore this effect, we investigate the structure and dynamics on various length scales in the simulations. We observe that a prepeak in the static structure factor S(q), which is related to a local segregation of aliphatic and hydroxyl groups, is accompanied by a peak in the correlation times τ(q) from coherent scattering functions.
The myth of wild dogs in Australia: are there any out there?
Authors: Cairns Kylie M. , Crowther Mathew S. , Nesbitt Bradley , Letnic Mike
Published: March 2021

Hybridisation between wild and domestic canids is a global conservation and management issue. In Australia, dingoes are a distinct lineage of wild-living canid with a controversial domestication status. They are mainland Australia’s apex terrestrial predator. There is ongoing concern that the identity of dingoes has been threatened from breeding with domestic dogs, and that feral dogs have established populations in rural Australia. We collate the results of microsatellite DNA testing from 5039 wild canids to explore patterns of domestic dog ancestry in dingoes and observations of feral domestic dogs across the continent. Only 31 feral dogs were detected, challenging the perception that feral dogs are widespread in Australia. First generation dingo × dog hybrids were similarly rare, with only 27 individuals identified. Spatial patterns of genetic ancestry across Australia identified that dingo populations in northern, western and central Australia were largely free from domestic dog introgression. Our findings challenge the perception that dingoes are virtually extinct in the wild and that feral dogs are common. A shift in terminology from wild dog to dingo would better reflect the identity of these wild canids and allow more nuanced debate about the balance between conservation and management of dingoes in Australia.
Tissue-restricted control of established central nervous system autoimmunity by TNF receptor 2–expressing Treg cells
Authors: Ronin Emilie , Pouchy Charlotte , Khosravi Maryam , Hilaire Morgane , Grégoire Sylvie , Casrouge Armanda , Kassem Sahar , Sleurs David , Martin Gaëlle H. , Chanson Noémie , Lombardi Yannis , Lalle Guilhem , Wajant Harald , Auffray Cédric , Lucas Bruno , Marodon Gilles , Grinberg-Bleyer Yenkel , Salomon Benoît L.
Published: March 2021

Significance

Regulatory T (Treg) cells have been highlighted for their central function in limiting the severity of autoimmune diseases such as multiple sclerosis (MS). To date, the anatomical location and timing of this Treg cell–mediated suppression are unknown. In this report, in a mouse model of MS, we demonstrate that Treg cells inhibit the pathogenic process directly in the central nervous system during established disease, rather than in the presymptomatic phase. This protective function requires the surface expression of TNF receptor 2 by Treg cells, as its genetic ablation or antibody-mediated blockade worsens disease symptoms. Our data reveal a unique function of Treg cells in autoimmunity and highlight TNFR2 as a promising therapeutic target.
Viral infection modulates Qa-1b in infected and bystander cells to properly direct NK cell killing
Authors: Ferez Maria , Knudson Cory J. , Lev Avital , Wong Eric B. , Alves-Peixoto Pedro , Tang Lingjuan , Stotesbury Colby , Sigal Luis J.
Published: March 2021

Natural killer (NK) cell activation depends on the signaling balance of activating and inhibitory receptors. CD94 forms inhibitory receptors with NKG2A and activating receptors with NKG2E or NKG2C. We previously demonstrated that CD94-NKG2 on NK cells and its ligand Qa-1b are important for the resistance of C57BL/6 mice to lethal ectromelia virus (ECTV) infection. We now show that NKG2C or NKG2E deficiency does not increase susceptibility to lethal ECTV infection, but overexpression of Qa-1b in infected cells does. We also demonstrate that Qa-1b is down-regulated in infected and up-regulated in bystander inflammatory monocytes and B cells. Moreover, NK cells activated by ECTV infection kill Qa-1b–deficient cells in vitro and in vivo. Thus, during viral infection, recognition of Qa-1b by activating CD94/NKG2 receptors is not critical. Instead, the levels of Qa-1b expression are down-regulated in infected cells but increased in some bystander immune cells to respectively promote or inhibit their killing by activated NK cells.
Gate Tunable Supercurrent in Josephson Junctions Based on Bi2Te3 Topological Insulator Thin Films
Authors: Wu Wei-Xiong , Feng Yang , Bai Yun-He , Jiang Yu-Ying , Gao Zong-Wei , Li Yuan-Zhao , Luan Jian-Li , Zhou Heng-An , Jiang Wan-Jun , Feng Xiao , Zhang Jin-Song , Zhang Hao , He Ke , Ma Xu-Cun , Xue Qi-Kun , Wang Ya-Yu
Published: March 2021

We report transport measurements on Josephson junctions consisting of Bi2Te3 topological insulator (TI) thin films contacted by superconducting Nb electrodes. For a device with junction length L = 134 nm, the critical supercurrent I
c can be modulated by an electrical gate which tunes the carrier type and density of the TI film. I
c can reach a minimum when the TI is near the charge neutrality regime with the Fermi energy lying close to the Dirac point of the surface state. In the p-type regime the Josephson current can be well described by a short ballistic junction model. In the n-type regime the junction is ballistic at 0.7 K < T < 3.8 K while for T < 0.7 K the diffusive bulk modes emerge and contribute a larger I
c than the ballistic model. We attribute the lack of diffusive bulk modes in the p-type regime to the formation of p–n junctions. Our work provides new clues for search of Majorana zero mode in TI-based superconducting devices.
Phase Stability and Hydroxyl Vibration of Brucite Mg(OH)2 at High Pressure and High Temperature
Authors: Gui Wei-Bin , Zhao Chao-Shuai , Liu Jin
Published: March 2021

Brucite Mg(OH)2 is an archetypal hydrous mineral and it has attracted a great deal of attention. However, little is known about the evolution of hydroxyl groups in brucite with respect to subduction fluids. We carried out Raman measurements up to 15.4 GPa and 874 K via an externally heated diamond anvil cell, investigating the stability of brucite under the conditions relevant to subducting slabs. The hydroxyl vibration mode A
1_g(I) of brucite is weakened under simultaneous high pressure-temperature conditions. Meanwhile, the presence of carbonated solution can destabilize the hydroxyl groups of brucite at low pressure. Our results suggest that brucite releases water when reacting with hydrogen carbonate ion to form magnesite MgCO3 in subduction zones. This implies that the global water cycle is largely coupled with the deep carbon cycle in Earth’s interior.
The enclosure method for a generalized anisotropic complex conductivity equation
Authors: Kuan Rulin
Published: March 2021

We study how to apply the enclosure method to reconstruct an unknown inclusion within a medium in a domain in

R

n

which satisfies the conductivity equation ∇ ⋅ ((σ
0 + iɛ
0)∇u) = 0 with σ
0 and ɛ
0 being real matrix functions. Motivated by some real world applications, we assume the unknown inclusion satisfies an equation of the more general form

∇
⋅

(

(

σ
+
i
ε

)

∇
u
+
ζ

∇
u

̄

)

=
0

, where σ, ɛ, ζ are also real matrix functions. Due to the anisotropy, it is in general difficult to find complex geometric optics solutions. Therefore, we construct the oscillating decaying solutions, which is used to test whether a given half-space intersects the unknown inclusion or not.
Spectroscopic ellipsometry of amorphous Se superlattices
Authors: John Joshua D , Okano Shun , Sharma Apoorva , Nishimoto Satoru , Miyachi Noritoshi , Enomoto Kunitaka , Ochiai Jun , Saito Ichitaro , Salvan Georgeta , Masuzawa Tomoaki , Yamada Takatoshi , Chua Daniel H C , Zahn Dietrich R T , Okano Ken
Published: March 2021

Superlattice structures have a variety of electrical and optical properties that allow for interesting applications like quantum cascade lasers and ultrasensitive photo-detectors. However, such structures require high-tech fabrication methods like molecular beam epitaxy, and this technology barrier means that these promising devices are not in widespread use. Using the simple method of rotational evaporation, we fabricated films with alternating multi-nanolayers of amorphous selenium (Se) and arsenic selenide (As2Se3). We investigated the optical properties of the individual materials, and the resulting multi-layer structure using spectroscopic ellipsometry. The results were modeled using Cody–Lorentz oscillators to obtain the refractive index (n) and extinction coefficient (k). The models showed the optical band gaps of Se and As2Se3 to be 1.97 and 1.69 eV, respectively. The absorption coefficient (α) of the multi-layer structure showed a series of five ‘steps’ in energy at 1.72, 1.82, 1.89, 1.97, and 2.04 eV. These are confirmed to stem from the transitions between confined quantum well levels due to the superlattice structure. In this way, the optical measurement using spectroscopic ellipsometry confirms the possibility of fabricating good quality nanostructutres using amorphous materials and rotational evaporation.
Get on the BAND Wagon: a Bayesian framework for quantifying model uncertainties in nuclear dynamics
Authors: Phillips D R , Furnstahl R J , Heinz U , Maiti T , Nazarewicz W , Nunes F M , Plumlee M , Pratola M T , Pratt S , Viens F G , Wild S M
Published: March 2021

We describe the Bayesian analysis of nuclear dynamics (BAND) framework, a cyberinfrastructure that we are developing which will unify the treatment of nuclear models, experimental data, and associated uncertainties. We overview the statistical principles and nuclear-physics contexts underlying the BAND toolset, with an emphasis on Bayesian methodology’s ability to leverage insights from multiple models. In order to facilitate understanding of these tools, we provide a simple and accessible example of the BAND framework’s application. Four case studies are presented to highlight how elements of the framework will enable progress in complex, far-ranging problems in nuclear physics (NP). By collecting notation and terminology, providing illustrative examples, and giving an overview of the associated techniques, this paper aims to open paths through which the NP and statistics communities can contribute to and build upon the BAND framework.
EHD-jet patterned MoS2 on a high-k dielectric for high mobility in thin film transistor applications
Authors: Can Thi Thu Thuy , Ko Hak-Lim , Choi Woon-Seop
Published: March 2021

Solution synthesis of MoS2 precursor followed by direct printing could be an effective way to make printed electronic devices. A linear MoS2 pattern was obtained by an electrohydrodynamic (EHD)-jet printer with a sol-gel system without chemical vapor deposition. The morphology of the MoS2 after a transfer process was maintained without wrinkles or cracking, resulting in a smooth surface compared with that of spin-coated films. EHD-jet printed MoS2 was transferred onto high-k dielectric Al2O3 and used as a semiconductor layer in thin film transistor (TFT) devices. The printed MoS2 TFT has relatively good electrical characteristics, such as a linear field effect mobility, current ratio, and low subthreshold swing of 47.64 

±

 2.99 cm2 V−1 s−1, 7.39 

±

 0.12 × 106, and 0.7 

±

 0.05 V decade−1, respectively. This technique may have promise for future applications.
In situ synthesis of Fe-doped CrOOH nanosheets for efficient electrocatalytic water oxidation
Authors: Gao Min , Ma Ning , Yu Cuiping , Liu Yu
Published: March 2021

The oxygen evolution reaction (OER) is a process in electrochemical water splitting with sluggish kinetics that needs efficient non-noble-metal electrocatalysts. There have been few studies of CrOOH electrocatalysts for water oxidation due to their low performance. Herein, in situ synthesized Fe-doped CrOOH nanosheets on Ni foam (Fe-CrOOH/NF) were designed as electrocatalysts and performance in the OER was obviously improved. The effect of the amount of Fe doping was also investigated. Experiments revealed that the best performance of Fe-CrOOH/NF requires low overpotentials of 259 mV to reach 20 mA cm−2 together with a turnover frequency of 0.245 s−1 in 1.0 M KOH, which may suggest a new direction for the development of Fe-doped OER electrocatalysts.
Sulfonated covalent organic framework modified separators suppress the shuttle effect in lithium-sulfur batteries
Authors: Deng Xiaoyu , Li Yongpeng , Li Lv , Qiao Shaoming , Lei Da , Shi Xiaoshan , Zhang Fengxiang
Published: March 2021

Lithium-sulfur batteries (LSBs) have gained intense research enthusiasm due to their high energy density. Nevertheless, the ‘shuttle effect’ of soluble polysulfide (a discharge product) reduces their cycling stability and capacity, thus restricting their practical application. To tackle this challenging issue, we herein report a sulfonated covalent organic framework modified separator (SCOF-Celgard) that alleviates the shuttling of polysulfide anions and accelerates the migration of Li+ ions. Specifically, the negatively charged sulfonate can inhibit the same charged polysulfide anion through electrostatic repulsion, thereby improving the cycle stability of the battery and preventing the Li-anode from being corroded. Meanwhile, the sulfonate groups may facilitate the positively charged lithium ions to pass through the separator. Consequently, the battery assembled with the SCOF-Celgard separator exhibits an 81.1% capacity retention after 120 cycles at 0.5 C, which is far superior to that (55.7%) of the battery with a Celgard separator. It has a low capacity degradation of 0.067% per cycle after 600 cycles at 1 C, and a high discharge capacity (576 mAh g−1) even at 2 C. Our work proves that the modification of a separator with a SCOF is a viable and effective route for enhancing the electrochemical performance of a LSB.
The impact of path estimates in iterative ion CT reconstructions for clinical-like cases
Authors: Meyer Sebastian , Pinto Marco , Parodi Katia , Gianoli Chiara
Published: March 2021

Ion computed tomography (CT) promises to mitigate range uncertainties inherent in the conversion of x-ray Hounsfield units into ion relative stopping power (RSP) for ion beam therapy treatment planning. To improve accuracy and spatial resolution of ion CT by accounting for statistical multiple Coulomb scattering deflection of the ion trajectories from a straight line path (SLP), the most likely path (MLP) and the cubic spline path (CSP) have been proposed. In this work, we use FLUKA Monte Carlo simulations to investigate the impact of these path estimates in iterative tomographic reconstruction algorithms for proton, helium and carbon ions. To this end the ordered subset simultaneous algebraic reconstruction technique was used and coupled with a total variation superiorization (TVS). We evaluate the image quality and dose calculation accuracy in proton therapy treatment planning of cranial patient anatomies. CSP and MLP generally yielded nearly equal image quality with an average RSP relative error improvement over the SLP of 0.6%, 0.3% and 0.3% for proton, helium and carbon ion CT, respectively. Bone and low density materials have been identified as regions of largest enhancement in RSP accuracy. Nevertheless, only minor differences in dose calculation results were observed between the different models and relative range errors of better than 0.5% were obtained in all cases. Largest improvements were found for proton CT in complex scenarios with strong heterogeneities along the beam path. The additional TVS provided substantially reduced image noise, resulting in improved image quality in particular for soft tissue regions. Employing the CSP and MLP for iterative ion CT reconstructions enabled improved image quality over the SLP even in realistic and heterogeneous patient anatomy. However, only limited benefit in dose calculation accuracy was obtained even though an ideal detector system was simulated.
Automated brain structures segmentation from PET/CT images based on landmark-constrained dual-modality atlas registration
Authors: Chen Zhaofeng , Qiu Tianshuang , Tian Yang , Feng Hongbo , Zhang Yanjun , Wang Hongkai
Published: March 2021

Automated brain structures segmentation in positron emission tomography (PET) images has been widely investigated to help brain disease diagnosis and follow-up. To relieve the burden of a manual definition of volume of interest (VOI), automated atlas-based VOI definition algorithms were developed, but these algorithms mostly adopted a global optimization strategy which may not be particularly accurate for local small structures (especially the deep brain structures). This paper presents a PET/CT-based brain VOI segmentation algorithm combining anatomical atlas, local landmarks, and dual-modality information. The method incorporates local deep brain landmarks detected by the Deep Q-Network (DQN) to constrain the atlas registration process. Dual-modality PET/CT image information is also combined to improve the registration accuracy of the extracerebral contour. We compare our algorithm with the representative brain atlas registration methods based on 86 clinical PET/CT images. The proposed algorithm obtained accurate delineation of brain VOIs with an average Dice similarity score of 0.79, an average surface distance of 0.97 mm (sub-pixel level), and a volume recovery coefficient close to 1. The main advantage of our method is that it optimizes both global-scale brain matching and local-scale small structure alignment around the key landmarks, it is fully automated and produces high-quality parcellation of the brain structures from brain PET/CT images.
Simultaneous imaging of widely differing particle concentrations in MPI: problem statement and algorithmic proposal for improvement
Authors: Boberg Marija , Gdaniec Nadine , Szwargulski Patryk , Werner Franziska , Möddel Martin , Knopp Tobias
Published: March 2021

Magnetic particle imaging (MPI) is a tomographic imaging technique for determining the spatial distribution of superparamagnetic nanoparticles. Current MPI systems are capable of imaging iron masses over a wide dynamic range of more than four orders of magnitude. In theory, this range could be further increased using adaptive amplifiers, which prevent signal clipping. While this applies to a single sample, the dynamic range is severely limited if several samples with different concentrations or strongly inhomogeneous particle distributions are considered. One scenario that occurs quite frequently in pre-clinical applications is that a highly concentrated tracer bolus in the vascular system ‘shadows’ nearby organs with lower effective tracer concentrations. The root cause of the problem is the ill-posedness of the MPI imaging operator, which requires regularization for stable reconstruction. In this work, we introduce a simple two-step algorithm that increases the dynamic range by a factor of four. Furthermore, the algorithm enables spatially adaptive regularization, i.e. highly concentrated signals can be reconstructed with maximum spatial resolution, while low concentrated signals are strongly regularized to prevent noise amplification.
Three-dimensional visualization and improved quantification with super-resolution ultrasound imaging - validation framework for analysis of microvascular morphology using a chicken embryo model
Authors: Özdemir İpek , Johnson Kenneth , Mohr-Allen Shelby , Peak Kara E , Varner Victor , Hoyt Kenneth
Published: March 2021

The purpose of this study was to improve the morphological analysis of microvascular networks depicted in three-dimensional (3D) super-resolution ultrasound (SR-US) images. This was supported by qualitative and quantitative validation by comparison to matched brightfield microscopy and traditional B-mode ultrasound (US) images. Contrast-enhanced US (CEUS) images were collected using a preclinical US scanner (Vevo 3100, FUJIFILM VisualSonics Inc.) equipped with an MX250 linear array transducer. CEUS imaging was performed after administration of a microbubble (MB) contrast agent into the vitelline network of a developing chicken embryo. Volume data was collected by mechanically scanning the US transducer throughout a tissue volume-of-interest in 90 μm step increments. CEUS images were collected at each increment and stored as in-phase/quadrature data (2000 frames at 152 frames per sec). SR-US images were created for each cross-sectional plane using established data processing methods. All SR-US images were then used to reconstruct a final 3D volume for vessel diameter (VD) quantification and for surface rendering. VD quantification from the 3D SR-US data exhibited an average error of 6.1% ± 6.0% when compared with matched brightfield microscopy images, whereas measurements from B-mode US images had an average error of 77.1% ± 68.9%. Volume and surface renderings in 3D space enabled qualitative validation and improved visualization of small vessels below the axial resolution of the US system. Overall, 3D SR-US image reconstructions depicted the microvascular network of the developing chicken embryos. Improved visualization of isolated vessels and quantification of microvascular morphology from SR-US images achieved a considerably greater accuracy compared to B-mode US measurements.
Spherical plasma focus operated with nitrogen and neon gases for soft x-rays (bremsstrahlung radiation, line radiation, and radiative recombination)
Authors: Ay Yasar
Published: March 2021

X-ray emissions (bremsstrahlung radiation, line radiation, and radiative recombination) from spherical plasma focus (SPF) device are investigated with the developed spherical MHD model for nitrogen (N) and neon (Ne) gases with respect to gas pressure, which is varied from 0.1 Torr to 7 Torr. Ion density, plasma velocity, pinch temperature, and peak current are also calculated for N and Ne gases. The total capacitance, external inductance, charging voltage, and stored energy as the operational conditions of the SPF device in this study are 432 µF, 36 nH, 25 kV, and 135 kJ. The maximum current is achieved at 7 Torr for both N (1561 kA) and Ne (1525 kA). It is found that there is an optimum pressure point for both x-rays (bremsstrahlung radiation, line radiation, and radiative recombination) and the used gases (N and Ne), separately. While the optimum pressure of bremsstrahlung radiation for N and Ne gases are 0.9 Torr and 1 Torr, respectively, these optimum pressures of radiative recombination and line radiation are 1 Torr for N gas and 1.1 Torr for Ne gas, respectively. It is also found that line radiation constitutes the big portion of the soft x-ray (SXR) emissions from SPF device. Line radiations of N at 1 Torr and Ne at 1.1 Torr are 911 J (91% of total N SXRs) and 3036.5 J (93.1% of total Ne SXRs), respectively, which shows that SPF device can be considered as a good SXR source. Ion densities and peak currents at 7 Torr are calculated as 21.88 × 1023 m−3 with 1561 kA peak current for N gas and 15.98 × 1023 m−3 with 1525 kA peak current for Ne gas.
2D Particle-in-cell simulations of charged particle dynamics in geometrically asymmetric low pressure capacitive RF plasmas
Authors: Wang Li , Hartmann Peter , Donkó Zoltán , Song Yuan-Hong , Schulze Julian
Published: March 2021

Understanding the spatio-temporal dynamics of charged particles in low pressure radio frequency capacitively coupled plasmas (CCP) is the basis for knowledge based process development in these plasma sources. Due to the importance of kinetic non-local effects the particle in cell/Monte Carlo collision (PIC/MCC) simulation became the primary modeling approach. However, due to computational limitations most previous PIC/MCC simulations were restricted to spatial resolution in one dimension. Additionally, most previous studies were based on oversimplified treatments of plasma-surface interactions. Overcoming these problems could clearly lead to a more realistic description of the physics of these plasma sources. In this work, the effects of the reactor geometry in combination with realistic heavy particle and electron induced secondary electron emission coefficients (SEEC) on the charged particle dynamics are revealed by GPU based 2D3V PIC/MCC simulations of argon discharges operated at 0.5 Pa and at a high voltage amplitude of 1000 V. The geometrical reactor asymmetry as well as the SEECs are found to affect the power absorption dynamics and distribution functions of electrons and ions strongly by determining the sheath voltages and widths adjacent to powered and grounded surface elements as well as via the self-excitation of the plasma series resonance. It is noticed that secondary electrons play important roles even at low pressures. Electron induced secondary electrons (δ-electrons) are found to cause up to half of the total ionization, while heavy particle induced secondary electrons (γ-electrons) do not cause much ionization directly, but induce most of the δ-electron emission from boundary surfaces. The fundamental insights obtained into the 2D-space resolved charged particle dynamics are used to understand the formation of energy distribution functions of electrons and ions for different reactor geometries and surface conditions.
Resistive transition of hydrogen-rich superconductors
Authors: Talantsev Evgeny F , Stolze Karoline
Published: March 2021

Critical temperature, T
c, and transition width, ΔT
c, are two primary parameters of the superconducting transition. The latter parameter reflects the superconducting state disturbance originating from the thermodynamic fluctuations, atomic disorder, applied magnetic field, the presence of secondary crystalline phases, applied pressure, etc. Recently, Hirsch and Marsiglio (2021 Phys. Rev. B
103 134505, doi: 10.1103/PhysRevB.103.134505) performed an analysis of the transition width in several near-room-temperature superconductors and reported that the reduced transition width, ΔT
c/T
c, in these materials does not follow the conventional trend of transition width broadening in applied magnetic field observed in low- and high-T
c superconductors. Here, we present a thorough mathematical analysis of the magnetoresistive data, R(T, B), for the high-entropy alloy (ScZrNb)0.65[RhPd]0.35 and hydrogen-rich superconductors of Im-3m-H3S, C2/m-LaH10 and P63
/mmc-CeH9. We found that the reduced transition width, ΔT
c/T
c, in these materials follows a conventional broadening trend in applied magnetic field.
Grain boundary diffusion in bilayered Ag/Cu thin film under diffusion-induced and intrinsic stresses
Authors: Lian Songyou , Xu Congkang , Wang Jiangyong , Swart Hendrik C , Terblans Jacobus J
Published: March 2021

The influences of the diffusion-induced stress due to the difference in the radii of elements in an alloy and the intrinsic stress originating mainly from the surface or other kind of external stress, on the grain boundary diffusion are evaluated. A model for the grain boundary (GB) diffusion under stress is developed. The stress distributions are obtained for the cases that the free surface acts as a diffusion barrier or has a rapid surface diffusion. The average concentration depth profiles are simulated upon the change of the diffusion-induced stress, the intrinsic stress, the ratio of the volume diffusion coefficient to the grain boundary diffusion coefficient, and the diffusion time. The simulation results reveal that the tensile/compressive intrinsic stress hinder/enhance the grain boundary diffusion process. The developed model for the GB diffusion under stress is applied to the bilayered Ag/Cu film deposited on an inert substrate.
Unsupervised outlier detection in heavy-ion collisions
Authors: Thaprasop P , Zhou K , Steinheimer J , Herold C
Published: March 2021

We present different methods of unsupervised learning which can be used for outlier detection in high energy nuclear collisions. This method is of particular interest for heavy ion collisions where a direct comparison of experimental data to model simulations is often ambiguous and it is not easy to determine whether an observation is due to new physics, an incomplete understanding of the known physics or an experimental artefact. The UrQMD model is used to generate the bulk background of events as well as different variants of outlier events which may result from misidentified centrality or detector malfunctions. The methods presented here can be generalized to different and novel physics effects. To detect the outliers, dimensional reduction algorithms are implemented, speciftically the Principle Component Analysis (PCA) and Autoencoders (AEN). We find that mainly the reconstruction error is a good measure to distinguish outliers from background. The performance of the algorithms is compared using a ROC curve. It is shown that the number of reduced (encoded) dimensions to describe a single event contributes significantly to the performance of the outlier detection task. We find that the model which is best suited to separate outlier events requires a good performance in reconstructing events and at the same time a small number of parameters.
Finding proper time intervals for dynamic network extraction
Authors: Orman Günce Keziban , Türe Nadir , Balcisoy Selim , Boz Hasan Alp
Published: March 2021

Extracting a proper dynamic network for modeling a time-dependent complex system is an important issue. Building a correct model is related to finding out critical time points where a system exhibits considerable change. In this work, we propose to measure network similarity to detect proper time intervals. We develop three similarity metrics, node, link, and neighborhood similarities, for any consecutive snapshots of a dynamic network. Rather than a label or a user-defined threshold, we use statistically expected values of proposed similarities under a null-model to state whether the system changes critically. We experimented on two different data sets with different temporal dynamics: the Wi-Fi access points logs of a university campus and Enron emails. Results show that, first, proposed similarities reflect similar signal trends with network topological properties with less noisy signals, and their scores are scale invariant. Second, proposed similarities generate better signals than adjacency correlation with optimal noise and diversity. Third, using statistically expected values allows us to find different time intervals for a system, leading to the extraction of non-redundant snapshots for dynamic network modeling.
Developing a physics textbook based on the local wisdom of Hulu Sungai Selatan regency to train rakat mufakat characters
Authors: Fitriah L , Ma’rifah E , Misbah M
Published: March 2021

This research was conducted due to the unavailability of textbook in Basic Physics 1 course especially in heat and temperature topic containing the South Kalimantan local wisdom so that students did not understand their culture well. Furthermore, students’ learning outcome were still not good. Therefore, this study aimed at producing physics textbook that contained heat and temperature topic based on the local wisdom of Hulu Sungai Selatan (HSS) Regency in South Borneo Province which was feasible based on the validity, the effectiveness, and the achievement of rakat mufakat characters. This study was a research and development using the ADDIE model. The instruments used were validation sheet, questionnaire, and achievement test. The results showed that the validity of the textbook was in highly valid category, the effectiveness was in medium category, and the attainment of rakat mufakat character was in very good category. Therefore, it could be concluded based on this research that the physics textbook based on local wisdom of HSS Regency is feasible to use in Basic Physics 1 course to train rakat mufakat characters.
Students’ Mathematical Communication Ability in Solving Trigonometric Problems
Authors: Utami L F , Pramudya I , Slamet I
Published: March 2021

Mathematical communication ability is a person’s ability to convey mathematical ideas orally or in writing which are presented in the form of graphs, tables, diagrams, symbols, or mathematical models. The purpose of this study is to determine and describe the level of mathematical communication ability of students. This type of research is a qualitative descriptive study. The sampling technique was using a purposive sampling technique. The results showed that the percentage of students’ mathematical communication ability in the text writing indicator, 38% of students were in the poor category, 50% of students were in the moderate category, 11% of students were in a good category, and 4% of students were in the very good category. On the drawing indicator, 7% of students were in the poor category, 57% of students were in a low category, and 36% of students were in the moderate category. 14% of students were in the poor category, 50% of students were in a low category, 18% of students were in the moderate category, 11% of students were in a good category, and 7% of students were in the very good category.
Analysis of mathematical critical thinking skills: The impact of RMS (reading, mind mapping, and sharing) learning model assisted by PPW (props, powerpoint, and worksheet)
Authors: Mutiara Panca Ayu , Achmad Fafiru , Alief Maulana , Lindasari Lisa Mei , Supriadi Nanang , Putra Fredi Ganda , Kusuma Arie Purwa , Rahmawati Nurina Kurniasari
Published: March 2021

Mathematical critical thinking skills arerequired to improve the understanding of mathematics. The purpose of this research was to determine the influence of the RMS learning model (reading, mind mapping, and sharing) assisted by PPW (Props, PowerPoints, and Worksheets) toward students’ thinking skills. This research is experimental research with a quasi-experimental design. The cluster random sampling technique was used to determine the sample. The data collection techniques used were tests. Before the tests were administered, they were tested using the realistic test, validity test, difficulty test, and discrimination index test. The data analysis technique used in this research wasthe one-way ANAVA with unequal cells. The results of the analysis showed that: Fobserved= 3.101296 <Fcritical= 4.076109 which indicated that H0was rejected. This indicated that there was an influence of the RMS learning model assisted by PPW on the students’ thinking skills. Furthermore, concerning the hypothesis testing and data analysis, the result was that the RMS learning model assisted by PPW could significantly affect students’ mathematical critical thinking skills.
Analysis of mathematical creative thinking level based on logical mathematical intelligence
Authors: Prastika V Y A , Riyadi  , Siswanto
Published: March 2021

Creativity is an ability that must be developed from an early age. The ability to think creatively is also one of the higher-order thinking skills needed in the 21st century. This study aimed to analyze the level of mathematical creative thinking skills of students’ mathematical logical intelligence. Indicators on the ability to think creatively include fluency, flexibility, and novelty. The method used in this research was descriptive qualitative. Data filling methods were tests, interviews, and documentation. The results of this study revealed the profile of students’ level of mathematical critical thinking and logical mathematical intelligence, and showed that students who have high mathematical logical intelligence are at level 3 creative thinking (creative). Students who have mathematical moderate logical intelligence are at level 2 creative thinking (creative enough) and students who have low mathematical logical intelligence are at creative thinking level 0 (not creative). Therefore, based on the results of this study, we know that students who have high, medium, and low mathematical logical intelligence can solve math problems based on their creative thinking abilities.
Analysis of critical thinking in junior high school students through science learning in Indonesia: A systematic review
Authors: Billah Arif , Masykuri Mohammad , Sarwanto  , Sajidan
Published: March 2021

The purpose of this study was to see the results of the research analysis regarding the critical thinking of junior high school students through science lessons in Indonesia. This research was a systematic review of studies through the Scopus database. Search was done through nine stages with criteria at each predetermined stage, i.e.: stage I, initial search with the keywords “critical thinking” with the category “article title”; stage II, type of access “open access”; stage III, published in “2010 – 2018”; stage IV, “English” language; stage V, the type of source “journals and proceedings”; stage VI, keywords “critical thinking”; stage VII, “Indonesia” research location; stage VIII, field of study “Science”; and stage IX, “Junior High School” education level. Searching through these nine stages results in 13 articles. The focus of this study was to analyze critical thinking skills and the indicators used in these studies. Most studies reported that increasing the critical thinking skills of Junior High School students in Indonesia were still at a “moderate” level. This study recommends to do further research on experimentation-based learning with an environmental approach to enhance critical thinking skills.