bluuebunny/crossref_metadata_2025 huggingface dataset:
Insights into the dynamics of supercritical water flow using a two-phase approach
Authors: Tripathi Piyush Mani , Basu Saptarshi
Published: April 2021

A two-phase approach has been proposed to study the supercritical flow with heat transfer deterioration (HTD) phenomena so that an analogy can be derived between subcritical flow boiling and supercritical heat transfer. The volume of fluid multiphase model has been used to analyze the flow, and the simulation result reasonably predicts the wall temperature peaks. Moreover, the velocity and turbulent kinetic energy profiles at different axial locations explain the occurrence of HTD. The parametric study of the thermophysical properties revealed that the density variation is the primary cause of HTD in supercritical flows. Leaning onto this observation, the current study focuses on the forces generated due to the density variation. It suggests that for no HTD, buoyancy and inertia forces have to be of comparable magnitude throughout the flow. Mapping of volume fraction variable reveals a sudden jump in the lighter phase thickness near the wall at the site of HTD, which is also reflected as a maximum in the plot of nondimensional two-phase interface distance from the wall (P). However, this observation is only restricted to HTD caused by buoyancy. This can be used to draw analogy with the phenomenon of film boiling in subcritical fluids. In the end, a theoretical expression has been conceptualized for computing the phase boundary distance from the wall (h), which can serve as a fundamental length scale in supercritical flows as it marks the region of highest property gradient near the wall.
Half-Heusler thermoelectric materials
Authors: Xia Kaiyang , Hu Chaoliang , Fu Chenguang , Zhao Xinbing , Zhu Tiejun
Published: April 2021

Semiconducting half-Heusler compounds with the valence electron count of 18 have been identified as a class of promising high-temperature thermoelectric materials. Recently, nominal 19-electron half-Heusler compounds, traditionally regarded as metals, have gained reacquaintance and popularity due to their unexpected high thermoelectric performance and fascinating defective structure. In this Perspective, we summarize the current progress of 18-electron half-Heusler thermoelectric materials and focus on the discovery and challenge of the cation-deficient 19-electron half-Heusler compounds with the vacancy-related short-range order. Further outlook on the discovery of promising half-Heusler thermoelectrics and the insightful understanding of the defect-tailored thermoelectric properties are offered.
GRIN metamaterial generalized Luneburg lens for ultra-long acoustic jet
Authors: Lu Chunyao , Yu Run , Ma Qiujun , Wang Kangyu , Wang Jing , Wu Dawei
Published: April 2021

In this work, a 3D-printed mesoscale acoustic generalized Luneburg lens based on cylindrical metamaterial is proposed. Compared to isotropic lenses, we numerically and experimentally demonstrate a series of advantages of lens including the super long work distance (over 17λ, 20 kHz in air), without obvious sidelobe, and better acoustic impedance matching. The ray tracing method is revealed to interpret the ultra-long acoustic jets mechanism. The adjustment of the lattice unit composition allows for the manipulation of air and underwater acoustic waves. The present work inspires a straightforward strategy for ultra-long acoustic jets, with promising applications in imaging and treatment in biological tissues.
Formation of ultra-high-resistance Au/Ti/p-GaN junctions and the applications in AlGaN/GaN HEMTs
Authors: Zhou Guangnan , Jiang Yang , Yang Gaiying , Wang Qing , Fan Mengya , Jiang Lingli , Yu Hongyu , Xia Guangrui
Published: April 2021

We report a dramatic current reduction, or a resistance increase, by a few orders of magnitude of two common-anode Au/Ti/p-GaN Schottky junctions annealed within a certain annealing condition window (600–700 °C, 1–4 min). Results from similar common-anode Schottky junctions made of Au/p-GaN, Al/Ti/p-GaN, and Au/Ti/graphene/p-GaN junctions demonstrated that all three layers (Au, Ti, and p-GaN) are essential for the increased resistance. Scanning-transmission electron microscopy, Hall, and Raman measurements have been performed to investigate the mechanisms. Moreover, this high-resistance junction structure was employed in p-GaN gate AlGaN/GaN high electron mobility transistors. It was shown to be an effective gate technology that was capable of boosting the gate breakdown voltage from 9.9 to 12.1 V with a negligible effect on the threshold voltage or the sub-threshold slope.
One-dimensional edge contact to encapsulated MoS2 with a superconductor
Authors: Seredinski A. , Arnault E. G. , Costa V. Z. , Zhao L. , Larson T. F. Q. , Watanabe K. , Taniguchi T. , Amet F. , Newaz A. K. M. , Finkelstein G.
Published: April 2021

Establishing ohmic contact to van der Waals semiconductors such as MoS2 is crucial to unlocking their full potential in next-generation electronic devices. Encapsulation of few layer MoS2 with hBN preserves the material’s electronic properties but makes electrical contacts more challenging. Progress toward high quality edge contact to encapsulated MoS2 has been recently reported. Here, we evaluate a contact methodology using sputtered MoRe, a type II superconductor with a relatively high critical field and temperature commonly used to induce superconductivity in graphene. We find that the contact transparency is poor and that the devices do not support a measurable supercurrent down to 3 K, which has ramifications for future fabrication recipes.
Stochastic and spectra contents of detonation initiated by compressible turbulent thermodynamic fluctuations
Authors: Ladeinde Foluso , Oh HyeJin
Published: April 2021

A canonical system that contains the basic elements of detonation initiated by compressible turbulence thermodynamic fluctuations was proposed by Towery et al. [“Detonation initiation by compressible turbulence thermodynamic fluctuations,” Combust. Flame 213, 172–183 (2020)] and successfully tested using direct numerical simulation (DNS). In the present study, the DNS dataset is used to assess the applicability of a few compressible turbulence theories to the problem of detonation and to investigate some statistical aspects of the problem and the spectra of the turbulence kinetic energy (TKE) and reactive scalar fields within the context of detonating and deflagrating compressible flows. It has been found that scaling of the dilatational and solenoidal components of compressible turbulence as reported in the literature does not apply to the case of detonation or deflagration. Also, the detonating cases were found to have significantly lower Karlovitz numbers compared to the nondetonating ones and to conform to the Bray–Moss–Libby premixed combustion (bimodal probability density function) model for intense turbulence and large Damkhöler number. The nondetonating cases show distributed pdfs. The stronger combustion in the detonating cases shows effects on the spectra of the TKE and reactive scalars, particularly when the wavenumber is scaled with the Kolmogorov length and the Schmidt number.
Highly solar-blind ultraviolet selective metal-semiconductor-metal photodetector based on back-illuminated AlGaN heterostructure with integrated photonic crystal filter
Authors: Tan Ruining , Cai Qing , Wang Jin , Pan Danfeng , Li Zheyang , Chen Dunjun
Published: April 2021

In this paper, we proposed a back-illuminated metal-semiconductor-metal AlGaN heterostructure solar-blind ultraviolet (UV) photodetector integrated with a SiO2/Si3N4 one-dimensional photonic crystal (1D PC). The light absorption outside solar-blind ultraviolet caused by impurity and defect energy levels is significantly suppressed by the 1D PC. The fabricated device exhibits extremely low dark current of 2 pA at 20 V applied voltage, where light/dark current ratio exceeds 4000. Meanwhile, the photodetector demonstrates a manifest narrow-band solar-blind detection property. The optical modulations of heterostructure energy-band engineering and photonic crystal filter both contribute to the solar-blind absorbing selectivity. In addition, the finger-scaling effects are also investigated based on carrier transport mechanism. These results are anticipated to promote the evolution on design and fabrication of solar-blind UV photodetector.
Enhanced multiresolution wavelet analysis of complex dynamics in nonlinear systems
Authors: Pavlov A. N. , Pavlova O. N. , Semyachkina-Glushkovskaya O. V. , Kurths J.
Published: April 2021

Multiresolution wavelet analysis (MWA) is a powerful data processing tool that provides a characterization of complex signals over multiple time scales. Typically, the standard deviations of wavelet coefficients are computed depending on the resolution level and such quantities are used as measures for diagnosing different types of system behavior. To enhance the capabilities of this tool, we propose a combination of MWA with detrended fluctuation analysis (DFA) of detail wavelet coefficients. We find that such an MWA&DFA approach is capable of revealing the correlation features of wavelet coefficients in independent ranges of scales, which provide more information about the complex organization of datasets compared to variances or similar statistical measures of the standard MWA. Using this approach, we consider changes in the dynamics of coupled chaotic systems caused by transitions between different types of complex oscillations. We also demonstrate the potential of the MWA&DFA method for characterizing different physiological conditions by analyzing the electrical brain activity in mice.
Comparison of atmospheric pressure argon producing O(1S) and helium plasma jet on methylene blue degradation
Authors: Jaiswal S. , Aguirre E. M.
Published: April 2021

A solution of methylene blue dye was degraded under an atmospheric pressure plasma jet operating in a linear field configuration with pure argon or pure helium as working gases. Optical emission spectroscopy was carried out to understand the reactive species present with and without dye treatment. Both plasma jets contain reactive species such as OH, N2, and atomic oxygen (O). However, atomic oxygen takes a greatly different form depending on the working gas. In the argon plasma jet, we observe that most of the atomic oxygen produced is the O(1S)–O(1D) transition that also leads to the green colored plasma plume. On the other hand, the helium plasma jet produces the well known triplet states of oxygen at 777 and 844 nm. The absorption spectra confirmed the faster and more energy efficient degradation of the methylene blue dye when treated by the argon plasma jet. Argon plasma with enhanced atomic oxygen content can be utilized as a cheaper and efficient method for waste water treatment.
Stochastic evaluation of fourth-order many-body perturbation energies
Authors: Doran Alexander E. , Hirata So
Published: April 2021

A scalable, stochastic algorithm evaluating the fourth-order many-body perturbation (MP4) correction to energy is proposed. Three hundred Goldstone diagrams representing the MP4 correction are computer generated and then converted into algebraic formulas expressed in terms of Green’s functions in real space and imaginary time. They are evaluated by the direct (i.e., non-Markov, non-Metropolis) Monte Carlo (MC) integration accelerated by the redundant-walker and control-variate algorithms. The resulting MC-MP4 method is efficiently parallelized and is shown to display O(n5.3) size-dependence of cost, which is nearly two ranks lower than the O(n7) dependence of the deterministic MP4 algorithm. It evaluates the MP4/aug-cc-pVDZ energy for benzene, naphthalene, phenanthrene, and corannulene with the statistical uncertainty of 10 mEh (1.1% of the total basis-set correlation energy), 38 mEh (2.6%), 110 mEh (5.5%), and 280 mEh (9.0%), respectively, after about 109 MC steps.
Improving cold-atom sensors with quantum entanglement: Prospects and challenges
Authors: Szigeti Stuart S. , Hosten Onur , Haine Simon A.
Published: April 2021

Quantum entanglement has been generated and verified in cold-atom experiments and used to make atom-interferometric measurements below the shot-noise limit. However, current state-of-the-art cold-atom devices exploit separable (i.e., unentangled) atomic states. This perspective piece asks the question: can entanglement usefully improve cold-atom sensors, in the sense that it gives new sensing capabilities unachievable with current state-of-the-art devices? We briefly review the state-of-the-art in precision cold-atom sensing, focusing on clocks and inertial sensors, identifying the potential benefits entanglement could bring to these devices, and the challenges that need to be overcome to realize these benefits. We survey demonstrated methods of generating metrologically useful entanglement in cold-atom systems, note their relative strengths and weaknesses, and assess their prospects for near-to-medium term quantum-enhanced cold-atom sensing.
A Simple Isocratic HPLC Method for the Quantitation of 17 Cannabinoids
Authors: Galettis Peter , Williams Michelle , Gordon Rebecca , Martin Jennifer H.
Published: April 2021

Although cannabis has been used for several thousand years, the exact composition of the cannabinoids patients are administered for different symptoms has remained largely unknown. While this absence of catalogued information may be accepted in some cultures, the use of cannabis as a human product in the registered medicines setting requires knowing its composition so that doses can be standardised between patients. This is particularly so in clinical trials that are currently under way to determine the efficacy of a product. Although the major cannabinoids of interest to prescribers are well known – tetrahydrocannabinol and cannabidiol and the corresponding acids tetrahydrocannabinolic acid and cannabidiolic acid, the cannabis plant contains many more phytocannabinoids. We have developed and validated a robust and fast (11 min) isocratic HPLC method for the analysis of 17 phytocannabinoids. The method had an analytical range of 1–150 μg mL−1 for tetrahydrocannabinolic acid and cannabidiolic acid, 0.5–75 μg mL−1 for tetrahydrocannabinol and cannabidiol, and 0.5–20 μg mL−1 for the remaining 13 cannabinoids. The method had excellent repeatability with a relative standard deviation of between 5 and 14 % and a bias of between –8.6 and 6 % for the 17 cannabinoids. The method was applied to the analysis of medicinal cannabis products, including both flos and oils with results matching the supplier’s certificate of analysis. This simple fast isocratic method with basic HPLC equipment can be easily transferred to any analytical laboratory interested in the identification and quantitation of cannabinoids.
Learning the molecular grammar of protein condensates from sequence determinants and embeddings
Authors: Saar Kadi L. , Morgunov Alexey S. , Qi Runzhang , Arter William E. , Krainer Georg , Lee Alpha A. , Knowles Tuomas P. J.
Published: April 2021

Significance

The tendency of many cellular proteins to form protein-rich biomolecular condensates underlies the formation of subcellular compartments and has been linked to various physiological functions. Understanding the molecular basis of this fundamental process and predicting protein phase behavior have therefore become important objectives. To develop a global understanding of how protein sequence determines its phase behavior, we constructed bespoke datasets of proteins of varying phase separation propensity and identified explicit biophysical and sequence-specific features common to phase-separating proteins. Moreover, by combining this insight with neural network-based sequence embeddings, we trained machine-learning classifiers that identified phase-separating sequences with high accuracy, including from independent external test data.
Cotranscriptional R-loop formation by Mfd involves topological partitioning of DNA
Authors: Portman James R. , Brouwer Gwendolyn M. , Bollins Jack , Savery Nigel J. , Strick Terence R.
Published: April 2021

Significance

R-loop structures pose a threat to genomic integrity because their formation can lead to mutagenesis. Mutagenesis drives antibiotic resistance in bacteria and chemotherapy resistance in human cancers; therefore, it is important to understand how R-loops form. Using a combination of in vitro single-molecule experimentation and in vivo mutagenesis assays, we have shown how Mfd, a bacterial protein known for its role in DNA repair, can interact with RNA polymerase to form R-loops. This interaction generates a topological domain in DNA that is highly prone to R-loop formation. The observed mechanism relies on properties of Mfd that are shared by many other proteins, hinting that this is a potentially universal model for R-loop formation.
BABEL enables cross-modality translation between multiomic profiles at single-cell resolution
Authors: Wu Kevin E. , Yost Kathryn E. , Chang Howard Y. , Zou James
Published: April 2021

Significance

Simultaneous measurement of the DNA, RNA, and proteins of single cells can lead to important new insights but is experimentally challenging. This work introduces a deep learning algorithm that flexibly translates between chromatin, RNA, and protein profiles in single cells. This makes it possible to computationally synthesize matched multiomic measurements when only one modality is experimentally available. This algorithm complements experimental advances to efficiently achieve single-cell multiomic insight.
Riboflavin instability is a key factor underlying the requirement of a gut microbiota for mosquito development
Authors: Wang Yin , Eum Jai Hoon , Harrison Ruby E. , Valzania Luca , Yang Xiushuai , Johnson Jena A. , Huck Derek T. , Brown Mark R. , Strand Michael R.
Published: April 2021

Significance

Mosquitoes are major disease vectors that require a gut microbiota for development into adults under some conditions but not others. To determine the underlying mechanisms for this variation, we determined that dietary riboflavin rapidly decays under most environmental conditions that mosquitoes experience, which makes larvae reliant on their gut microbiota for this essential micronutrient. Our findings illustrate the value of being able to both control and manipulate dietary nutrients, microbiota composition, and environmental conditions in studying the role of gut microbes in animal biology. Our results also suggest environmental conditions are an understudied variable in why the gut microbiota is essential for provisioning certain essential vitamins in aquatic organisms like mosquito larvae.
Melanocortin 3 receptor-expressing neurons in the ventromedial hypothalamus promote glucose disposal
Authors: Sutton Hickey Amy K. , Goforth Paulette B. , Gonzalez Ian E. , Dell’Orco James , Pei Hongjuan , Myers Martin G. , Olson David P.
Published: April 2021

The ventromedial hypothalamus (VMH) is a critical neural node that senses blood glucose and promotes glucose utilization or mobilization during hypoglycemia. The VMH neurons that control these distinct physiologic processes are largely unknown. Here, we show that melanocortin 3 receptor (
Mc3R
)-expressing VMH neurons (VMH
MC3R
) sense glucose changes both directly and indirectly via altered excitatory input. We identify presynaptic nodes that potentially regulate VMH
MC3R
neuronal activity, including inputs from proopiomelanocortin (POMC)-producing neurons in the arcuate nucleus. We find that VMH
MC3R
neuron activation blunts, and their silencing enhances glucose excursion following a glucose load. Overall, these findings demonstrate that VMH
MC3R
neurons are a glucose-responsive hypothalamic subpopulation that promotes glucose disposal upon activation; this highlights a potential site for targeting dysregulated glycemia.
Bemisia tabaci (tobacco whitefly).
Authors: Cuthbertson Andrew
Published: April 2021

The Bemisia tabaci complex is polyphagous and now attacks many crops, but without significant impact on land use. Any effects on biodiversity would result indirectly from an increased use of insecticides against this pest.
Design of 1300 nm spectral domain optical coherence tomography angiography system for iris microvascular imaging
Authors: Lan Gongpu , Xu Jingjiang , Hu Zhilin , Huang Yanping , Wei Yingzhao , Yuan Xing , Liu Huazong , Qin Jia , Wang Yicheng , Shi Qun , Zeng Jun , Shi Yue , Feng Jinping , Tan Haishu , An Lin , Wei Xunbin
Published: April 2021

Developing a high-resolution non-invasive optical coherence tomography angiography (OCTA) method for iris vasculature imaging is essential for diagnosing a wide range of ocular pathologies. However, the current iris-OCTA devices are still limited in imaging quality and penetration depth for dark-colored eyes ranging from brown to dark brown. A spectral domain iris-OCTA system is presented in this paper incorporating a 1300 nm wavelength for deeper tissue penetration, a linear-wavenumber spectrometer for better detection sensitivity, and an iris scan objective lens for better optical focusing across the entire iris over a 12 × 12 mm2 scan field. The −6 dB fall-off range is ∼3 mm, and the maximum sensitivity fall-off is −28.57 dB at 6.94 mm. The axial resolution is 15.1 ± 3.2 μm. The 40 mm focal-length iris scan objective is optimized based on the ocular parameters from 100 Asian participants’ left eyes, and it has a diffraction-limited lateral resolution (14.14 μm) for the iris, in general. OCT distortions were calibrated based on the average ocular parameters, and the maximum residual distortions in both the lateral and axial directions were <0.1 mm (2.0%) for all of the eyes. A pilot study on a constricted pupil was performed to demonstrate high-contrast, wide-field en face iris microvascular imaging by either a horizontal or vertical fast-scan protocol in a dark brown eye. The iris vessels are radially aligned, and each vessel is more visible when it has an angle of ∼65°–90° with respect to the fast-scan direction. A new circular fast-scan protocol could improve image quality for better visualization of the iris features or integration with image-registration algorithms and an eye-tracking system for eye-motion compensation.
Structure of levitated Si–Ge melts studied by high-energy x-ray diffraction in combination with reverse Monte Carlo simulations
Authors: Pozdnyakova Irina , Roik Oleksandr , Drewitt James W E , Bytchkov Aleksei , Kargl Florian , Jahn Sandro , Brassamin Séverine , Hennet Louis
Published: April 2021

The short-range order in liquid Si, Ge and binary Si
x
–Ge1−x
alloys (x = 0.25, 0.50, 0.75) was studied by x-ray diffraction and reverse Monte Carlo simulations. Experiments were performed in the normal and supercooled liquid states by using the containerless technique of aerodynamic levitation with CO2 laser heating, enabling deeper supercooling of liquid Si and Si–Ge alloys than previously reported. The local atomic structure of liquid Si and Ge resembles the β-tin structure. The first coordination numbers of about 6 for all compositions are found to be independent of temperature indicating the supercooled liquids studied retain this high-density liquid (HDL) structure. However, there is evidence of developing local tetrahedral ordering, as manifested by a shoulder on the right side of the first peak in S(Q) which becomes more prominent with increasing supercooling. This result is potentially indicative of a continuous transition from the stable HDL β-tin (high pressure) phase, towards a metastable low-density liquid phase, reminiscent of the diamond (ambient pressure) structure.
Effective velocities of polaron spin states in monolayer transition metal dichalcogenides
Authors: Sun Yong , Ma Xu-Fei , Liu Xiao-Yi , Cui Yu , Deng Jia-Pei , Xiao Yao , Li Zhi-Qing , Wang Zi-Wu
Published: April 2021

We propose a theoretical model for studying the effective velocities of polaron spin states in monolayer transition metal dichalcogenides (TMDS) on the substrate. It is found that the effective velocity of polaron shows the splitting with different magnitudes due to the Rashba spin–orbit coupling, which results in the reversed distribution of the effective velocities of polaron spin states. Moreover, the reversed points depend on the truncated wave-vector of optical phonon and can be modulated by the polarity of substrate and the internal distance between monolayer TMDS and substrate. These theoretical results enlighten some simple ways to distinguish and modulate the polaron spin states in two-dimensional heterostructures.
Torsional moduli of transition metal dichalcogenide nanotubes from first principles
Authors: Bhardwaj Arpit , Sharma Abhiraj , Suryanarayana Phanish
Published: April 2021

We calculate the torsional moduli of single-walled transition metal dichalcogenide (TMD) nanotubes usingab initiodensity functional theory (DFT). Specifically, considering forty-five select TMD nanotubes, we perform symmetry-adapted DFT calculations to calculate the torsional moduli for the armchair and zigzag variants of these materials in the low-twist regime and at practically relevant diameters. We find that the torsional moduli follow the trend: MS2> MSe2> MTe2. In addition, the moduli display a power law dependence on diameter, with the scaling generally close to cubic, as predicted by the isotropic elastic continuum model. In particular, the shear moduli so computed are in good agreement with those predicted by the isotropic relation in terms of the Young’s modulus and Poisson’s ratio, both of which are also calculated using symmetry-adapted DFT. Finally, we develop a linear regression model for the torsional moduli of TMD nanotubes based on the nature/characteristics of the metal-chalcogen bond, and show that it is capable of making reasonably accurate predictions.
High-sensitivity tactile sensor based on Ti2C-PDMS sponge for wireless human–computer interaction
Authors: Sun Peng , Wu Dongping , Liu Chaoran
Published: April 2021

Tremendous attention has been paid to high-performance flexible tactile sensors owing to their potential applications in bionic skin, wearable electronics, the Internet of Things, etc. However, the majority of pressure sensors require an intricately designed nanostructure requiring a high-cost complex manufacturing process. Therefore, the high-throughput and low-cost technology to produce high-sensitivity, flexible, pressure-sensitive materials with a large responding range is urgently needed. Herein, a novel flexible piezoresistive tactile sensor is fabricated based on the Ti2C-PDMS sponge as the conductive elastomer. The sensor exhibits a high sensitivity of 279 kPa−1 in a wide pressure range (0–34.4 kPa). The response time is as fast as 0.45 s with excellent durability over 4,000 cycles. Moreover, a 16-pixel wireless sensor system is fabricated and a series of applications have been demonstrated, including real-time force perception and pressure morphology feedback, which promote the potential applications in the visualizing of pressure distribution, human–machine communication and wearable devices.
Simultaneous multi-slice accelerated 4D-MRI for radiotherapy guidance
Authors: Keijnemans K , Borman P T S , van Lier A L H M W , Verhoeff J J C , Raaymakers B W , Fast M F
Published: April 2021

4D-MRI is becoming increasingly important for daily guidance of thoracic and abdominal radiotherapy. This study exploits the simultaneous multi-slice (SMS) technique to accelerate the acquisition of a balanced turbo field echo (bTFE) and a turbo spin echo (TSE) coronal 4D-MRI sequence performed on 1.5 T MRI scanners. SMS single-shot bTFE and TSE sequences were developed to acquire a stack of 52 coronal 2D images over 30 dynamics. Simultaneously excited slices were separated by half the field of view. Slices intersecting with the liver-lung interface were used as navigator slices. For each navigator slice location, an end-exhale dynamic was automatically identified, and used to derive the self-sorting signal by rigidly registering the remaining dynamics. Navigator slices were sorted into 10 amplitude bins, and the temporal relationship of simultaneously excited slices was used to generate sorted 4D-MRIs for 12 healthy volunteers. The self-sorting signal was validated using an in vivo peak-to-peak motion analysis. The smoothness of the liver-lung interface was quantified by comparing to sagittal cine images acquired directly after the SMS-4D-MRI sequence. To ensure compatibility with the MR-linac radiotherapy workflow, the 4D-MRIs were transformed into 3D mid-position (MidP) images using deformable image registration. Consistency of the deformable vector fields was quantified in terms of the distance discordance metric (DDM) in the body. The SMS-4D-TSE sequence was additionally acquired for 3 lung cancer patients to investigate tumor visibility. SMS-4D-MRI acquisition and processing took approximately 7 min. 4D-MRI reconstruction was possible for 26 out of 27 acquired datasets. Missing data in the sorted 4D-MRIs varied from 4%–26% for the volunteers and varied from 8%–24% for the patients. Peak-to-peak (SD) amplitudes analysis agreed within 1.8 (1.1) mm and 0.9 (0.4) mm between the sorted 4D-MRIs and the self-sorting signals of the volunteers and patients, respectively. Liver-lung interface smoothness was found to be in the range of 0.6–3.1 mm for volunteers. The percentage of DDM values smaller than 2 mm was in the range of 85%–89% and 86%–92% for the volunteers and patients, respectively. Lung tumors were clearly visibility in the SMS-4D-TSE images and MidP images. Two fast SMS-accelerated 4D-MRI sequences were developed resulting in T2/T1 or T2 weighted contrast. The SMS-4D-MRIs and derived 3D MidP-MRIs yielded anatomically plausible images and good tumor visibility. SMS-4D-MRI is therefore a strong candidate to be used for treatment simulation and daily guidance of thoracic and abdominal MR-guided radiotherapy.
Influence of up-down asymmetry in plasma shape on RMP response
Authors: Liu Yueqiang , Lyons B C , Gu Shuai , Kirk A , Li Li , Paz-Soldan C , Shafer M W , Turnbull A D
Published: April 2021

Shaping effect on the plasma response to the externally applied resonant magnetic perturbation field is investigated for both DIII-D and MAST experiments, utilizing toroidal modeling. The plasma boundary shape is systematically varied ranging from single-null (SN) to double-null (DN) configurations, while other equilibrium quantities are kept largely unchanged. The relative amplitude of the computed plasma surface displacement, between the top/bottom of the torus and the outboard mid-plane, is identified as the most reliable indicator that distinguishes the plasma response between the SN and DN configurations. The underlying physics is the weakening of the edge-peeling component in the plasma response with increasing up-down symmetry of the plasma boundary shape.
Studies of a modulated Hall thruster
Authors: Simmonds Jacob , Raitses Yevgeny , Smolyakov Andrei , Chapurin Oleksandr
Published: April 2021

A typical Hall thruster is powered from a DC power supply and operates with a constant discharge voltage. In operation, the discharge current is subject to strong low frequency oscillations (so-called breathing oscillations). Recent studies have shown that not only can these breathing oscillations be correlated with improved performance, but these oscillations can be induced and controlled by modulating the anode voltage. In this work, a systematic experimental study of the plasma flow in a modulated cylindrical Hall thruster was performed to characterize the effect of natural and modulated breathing oscillations on thruster performance. Measurements suggest that modulating the anode voltage in resonance with the natural breathing frequency does increase the thrust, but a corresponding phase alignment of discharge current and discharge voltage causes the efficiency gains to be insignificant. In addition, the outward shift of the acceleration region causes the plasma plume divergence to increase at the resonance condition and thereby, limit the thrust increase. Mechanisms underlying the relative phase between discharge current, ion current, and discharge voltage are investigated experimentally and corroborated with one-dimensional hybrid simulations of the thruster discharge.
Phosphorus implantation into 4H-SiC at room and elevated temperature
Authors: Müting J , Bobal V , Vines L , Grossner U
Published: April 2021

Phosphorus implantation is essential to create localized n-type doped regions in 4H-SiC. The realized profiles may, however, deviate from the desired ones, affecting device properties. In order to characterize typical process parameters and to enable correct prediction of the desired structures, phosphorous implantation into 4H-SiC with a variety of doses and energies is performed at room and elevated temperature. Exemplary post-implantation annealing shows no significant influence on the phosphorus distribution. The as-implanted profiles, analyzed by secondary ion mass spectrometry, show a clear dependence on implantation dose and temperature. High sample temperature at implantation suppresses channeling in case of low and medium doses due to increased lattice vibrations, while crystal damage is restored in case of high doses leading to increased opportunities for channeling, pointing toward different crystal damage and energy loss mechanisms. Finally, the Monte Carlo profiles of the simulation tools stopping and range of ions in matter (SRIM) and Sentaurus Process are critically compared with the experimental profiles.
Modelling of minor hysteresis loop of shape memory alloy wire actuator and its application in self-sensing
Authors: Mohan Sagar , Banerjee Atanu
Published: April 2021

Shape memory alloy (SMA) wire actuators offer large force and displacement capabilities out of the stress and temperature-dependent martensitic phase transformation. Among the various modelling approaches in the literature, the one proposed by Boyd and Lagoudas (1996), is mostly used in analysing SMA based components. In practice, partial actuation is often required and is enacted by aborting and subsequently resuming the phase transformation; exhibiting minor hysteresis response. The existing models are found to be inaccurate in simulating such partial transformation cases. In this study, a novel yield parameter, which depends on the martensite volume fraction, has been proposed; enabling the model of Boyd and Lagoudas to simulate minor hysteresis loop accurately. The corresponding model parameters are derived, satisfying certain practical aspects of the SMA response. Using the modified model, pseudoelastic responses are simulated for different partial loading cases and are compared against the same obtained from the existing models, illustrating its efficacy. Following the proposed model, the discrete form of the system dynamics of a SMA wire actuator is formulated. Using this, an extended Kalman filter (EKF) has been developed, to estimate the output of the system from the change in electrical resistance of the SMA wire during actuation. This approach eliminates the requirement of external sensors for feedback control. Using the developed EKF, the response of an SMA wire actuated system is estimated from the experimentally measured electrical resistance data of the SMA wire and are compared with the corresponding measured responses. The results reveal that a significant level of accuracy can be achieved with the proposed approach.
Radiative heat transfer of second grade nanofluid flow past a porous flat surface: a single-phase mathematical model
Authors: Jamshed Wasim , Nisar Kottakkaran Sooppy , Gowda R J Punith , Kumar R Naveen , Prasannakumara B C
Published: April 2021

The current study explores the nanofluid flow and heat transfer properties by exposing it to a slippery surface. The effect of radiation, heat source, porous medium, and viscous dissipation are also comprised in this analysis. The arising partial differential equations from boundary layer equations of the second grade nanoliquid model are reformed into non-linear ordinary differential equations using suitable transformations. The solution of these equations is then cracked by means of shooting numerical scheme. In this investigation, we used two different types of nanoparticles, Alumina (Al2O3) and Copper (Cu), along with a non-Newtonian Engine Oil (EO) as based liquid. The valuable finding of this scrutiny is that the comparative heat transference rate of Cu-EO second grade nanofluids gradually more increases as compared to Al2O3-EO nanofluids. Results reveal that, the parameters have a massive effect on the heat transfer very close to the wall and are slightly away from the wall. The escalation in nanoparticle volume fraction and second grade parameters declines the velocity profile.
Weakening gravity for dark matter in a type-II minimally modified gravity
Authors: De Felice Antonio , Mukohyama Shinji
Published: April 2021

We propose a new cosmological framework in which the strength of the gravitational force acted on dark matter at late time can be weaker than that on the standard matter fields without introducing extra gravitational degrees of freedom. The framework integrates dark matter into a type-II minimally modified gravity that was recently proposed as a dark energy mimicker. The idea that makes such a framework possible consists of coupling a dark matter Lagrangian and a cosmological constant to the metric in a canonically transformed frame of general relativity (GR). On imposing a gauge fixing constraint, which explicitly breaks the temporal diffeomorphism invariance, we keep the number of gravitational degrees of freedom to be two, as in GR. We then make the inverse canonical transformation to bring the theory back to the original frame, where one can add the standard matter fields. This framework contains two free functions of time which specify the generating functional of the above mentioned canonical transformation and which are then used in order to realize desired time evolutions of both the Hubble expansion rate H(z) and the effective gravitational constant for dark matter Geff(z). The aim of this paper is therefore to provide a new framework to address the two puzzles present in today's cosmology, i.e. the H0 tension and the S8 tension, simultaneously. When the dark matter is cold in this framework, we dub the corresponding cosmological model the V Canonical Cold Dark Matter (VCCDM), as the cosmological constant Λ in the standard ΛCDM is replaced by a function V(ϕ) of an auxiliary field ϕ and the CDM is minimally coupled to the metric in a canonically transformed frame.
Resetting with stochastic return through linear confining potential
Authors: Gupta Deepak , Pal Arnab , Kundu Anupam
Published: April 2021

We consider motion of an overdamped Brownian particle subject to stochastic resetting in one dimension. In contrast to the usual setting where the particle is instantaneously reset to a preferred location (say, the origin), here we consider a finite time resetting process facilitated by an external linear potential V(x) = λ|x|(λ > 0). When resetting occurs, the trap is switched on and the particle experiences a force −∂
x

V(x) which helps the particle to return to the resetting location. The trap is switched off as soon as the particle makes a first passage to the origin. Subsequently, the particle resumes its free diffusion motion and the process keeps repeating. In this set-up, the system attains a non-equilibrium steady state. We study the relaxation to this steady state by analytically computing the position distribution of the particle at all time and then analyzing this distribution using the spectral properties of the corresponding Fokker–Planck operator. As seen for the instantaneous resetting problem, we observe a ‘cone spreading’ relaxation with travelling fronts such that there is an inner core region around the resetting point that reaches the steady state, while the region outside the core still grows ballistically with time. In addition to the unusual relaxation phenomena, we compute the large deviation functions (LDFs) associated to the corresponding probability density and find that the LDFs describe a dynamical transition similar to what is seen previously in case of instantaneous resetting. Notably, our method, based on spectral properties, complements the existing renewal formalism and reveals the intricate mathematical structure responsible for such relaxation phenomena. We verify our analytical results against extensive numerical simulations.
The diffusive epidemic process on Barabasi–Albert networks
Authors: Alves T F A , Alves G A , Macedo-Filho A , Ferreira R S , Lima F W S
Published: April 2021

We present a modified diffusive epidemic process (DEP) that has a finite threshold on scale-free graphs, motivated by the COVID-19 pandemic. The DEP describes the epidemic spreading of a disease in a non-sedentary population, which can describe the spreading of a real disease. Our main modification is to use the Gillespie algorithm with a reaction time t
max, exponentially distributed with mean inversely proportional to the node population in order to model the individuals’ interactions. Our simulation results of the modified model on Barabasi–Albert networks are compatible with a continuous absorbing-active phase transition when increasing the average concentration. The transition obeys the mean-field critical exponents β = 1, γ′ = 0 and ν
⊥ = 1/2. In addition, the system presents logarithmic corrections with pseudo-exponents

β

̂

=

γ

̂

′

=
−
3
/
2

on the order parameter and its fluctuations, respectively. The most evident implication of our simulation results is if the individuals avoid social interactions in order to not spread a disease, this leads the system to have a finite threshold in scale-free graphs.
Study of Mechanical Properties and Thermal Conductivity of Polymeric Blend [Epoxy and polysulfide rubber (EP + PSR)] Reinforced by Nano Ceramic Powder ZrO2
Authors: Shalaan Muna M , AL-Falahi Ahmad H M , AL-Dabagh Balkees M
Published: April 2021

A polymeric blend nanocomposites were prepared using mixer of Epoxy and polysulfide rubber [EP+PSR] as a matrix material and the Zirconium Oxide Nano-powder ZrO2as a reinforcement material, in different particle sizes and same adding ratio of 2% wt . Hand Lay-up molding method was used to prepare the samples. Impact strength, compression resistance and thermal conductivity tests, were carried out for the polymeric blend and composites samples before and after immersion in tap water. The results showed that adding Nano zirconia powder to the polymer blend improved the mechanical properties, while the thermal conductivity of the polymer blend was higher than that of the composites. Also, it was observed that water immersion caused a decrease in impact strength, compression resistance, modulus of elasticity and thermal conductivity in a manner proportional to the immersion time.
Effect of Adding Ag Nanoparticles onto Magnetic and Structural Properties of BSCCO Superconducting Compound
Authors: Al Habeeb Mustafa Q. , Oboudi Saad , Wenlong Wu , Julian Stephen
Published: April 2021

Effect of adding silver nanoparticles on Bi1.7Pb0.3Sr2Ca2Cu3O10+δ superconductor phase by solid state reaction technique. It was studied the significant variations in the superconducting, magnetic and structural properties of Bi-2223 phase. Ag NPs concentration of tiny particles varied, (0 - 1,25) % from the total weight mass of the BPSCCO compound were characterized by X-ray diffraction (XRD) and EDX spectrum measurements. It was found that adding Ag nanoparticles to BSCCO was enhanced the (Bi, Pb)-2223 phase formation up to x=1.25 wt%. On the other hand, the low concentrations of Ag nanoparticles of 0.25 wt% retarded the high-Tc phase formation and (Tc) measured that had the maximum improvement in Tc for most samples. The surface morphology investigated were examined by SEM, which the grain size increased with an increase Ag NPs, while the grain size examination showed that both the size and number of voids were reduced. Magnetization variance was measured of the samples by M - T curve, where the highest value for x = 1.25 wt%, and it become clear when the magnetic and resistance transition points are close to each other. Moreover, Critical current density (Jc
) characteristic curves were measured at temperature range (2-150) K.
Optimization Approach of Multilayer (Metal-Dielectric) Pass Band Filter
Authors: Abd algaffar Alaa N , Jasem Narmeen A , Abbo Abdullah I
Published: April 2021

This study presents new construction design stacks for optimal narrow band pass filters in two different spectral regions. The new design of narrow pass band filters have optimal specifications as narrow pass band, high transmittance, and zero transmittance at stop band along wide range of wavelength. Procedures were given to design such filters by adjusting metal with dielectric materials. We investigated the construction stacks to have proper number of coating layers with controlling the thickness of each layer.
Data visualization for distribution of people with disabilities
Authors: Baharum Z , Amran A , Kamsul B A , Ahmad N A , Azmi N H
Published: April 2021

Data visualizations make data easier for the human brain to understand, and visualization also makes it easier to detect patterns, trends, and styles in groups of data. With the development of the data visualization, more and more data which contains the information of disabled population has been collected. However, researchers have pointed out some problems with visualizing data especially using traditional methods. Therefore, this study aimed to develop a web-based system for data visualization of disabled people distribution in Kuala Selangor, Selangor, Malaysia. Prototyping methodology was chosen in order to develop the web-based system. The results show two main interfaces of the web system which are the admin module and user module. Users may see a specific area, type of disabled people categories and the number of disabled people in the located area from the Google Map. This web system is hope to help public in identifying disabled people location using data visualization technique. In addition, in future it could help the authorize institutions/bodies in doing better planning for disabled people education, facilities and other needs based on its location distribution.
Digital map of zoo negara using geospatial information system (GIS) approach
Authors: Juarimi N A A B , Nasir N R M
Published: April 2021

National Zoo of Malaysia or Zoo Negara is one of popular tourist attraction places in Malaysia that receives many visitors every day. Providing the best service and tour information for large volume of visitors every day is the main objective of Zoo Negara. However, the current issue facing by Zoo Negara is its current information medium where they still use printed paper-based mapping system. This medium is not helpful enough for the visitors to navigate inside the zoo as the information is insufficient and troubles Zoo Negara management in updating their map as well. In this paper, we propose a GIS-mobile based application that provides visitors with digital map. The digital map includes information about animals and events inside the zoo. Visitor can also view their current location and visited track on the map using navigation module. Zoo Negara management can regularly update their map and recent information easily through database.