bluuebunny/crossref_metadata_2025 huggingface dataset:
Subpial Schwannoma of the Cervical Spinal Cord: A Case Report and Its Intraoperative Finding Supporting a Theory of the Pathogenesis of an Intramedullary Schwannoma
Authors: Decharin Payothorn , Suvithayasiri Siravich , Nivatpumin Padungcharn , Trathitephun Warayos
Published: June 2022

Because of its tumor origin from nerve sheath cells (the Schwann cells), the pathogenesis of an extraordinary rare intramedullary schwannoma, which should not have any Schwann's cells in nature, is controversial and still in debate. We report a case of a 63-year-old man diagnosed with a cervical cord intramedullary schwannoma with an interesting intraoperative finding that could support one of the theories on its genesis.
Remote Intramedullary Hemorrhage in the Thoracic Spinal Cord Secondary to a Perimedullary Arteriovenous Fistula of the Distal End of Conus Medullaris Mimicking Filum Terminale Arteriovenous Fistula: A Case Report
Authors: Iampreechakul Prasert , Liengudom Anusak , Lertbutsayanukul Punjama , Siriwimonmas Somkiet , Pongpech Sirintara
Published: June 2022

Perimedullary arteriovenous fistulas (PMAVFs) of the conus medullaris are rare and usually manifest with progressive myelopathy secondary to venous congestion resulting from retrograde arterialization of the draining vein into the spinal cord. We present a rare case of conus PMAVF presenting with remote intramedullary spinal cord hemorrhage in the thoracic cord. A 37-year-old woman was transferred to our institute due to sudden severe pain in the left lower leg and weakness of the lower extremities following progressive paresthesia of the lower extremities. Magnetic resonance imaging of the thoracic and lumbosacral spine revealed spinal cord congestion extending from the conus medullaris to the level of T6 with intramedullary hemorrhage at the level of T8–9 on the left side of the spinal cord. There were abnormal serpiginous intradural flow voids along the anterior surface of the spinal cord extending from the level of L2 to the lower cervical with venous varix at the level of T8–9, probably being the source of hemorrhage. Spinal angiography confirmed conus PMAVF at the distal end of the conus medullaris supplied by the sulco-commissural artery arising from the enlarged anterior spinal artery originating from the left T11 intercostal artery with cranial drainage through the dilated anterior spinal vein into the tortuous perimedullary veins up to the lower cervical level. The patient underwent successful endovascular treatment with N-butyl cyanoacrylate and had gradually improved until being ability to walk independently without residual pain of the left lower leg. We speculated that an increased venous flow into a varix may be considered an important risk factor of hemorrhage.
Perfusion Strategies for Bivalirudin Anticoagulation: AIIMS Protocol
Authors: Sharma Gaurav , Hasija Suruchi , Kapoor Poonam Malhotra
Published: June 2022

Anticoagulation strategies for cardiac surgery are witnessing a change with the identification of serious limitations of heparin, including development of resistance in 3 to 13% of patients undergoing cardiac surgery and heparin-induced thrombocytopenia/thrombosis syndrome in 1 to 5.5% of patients. Heparin alternatives have a potential role in these scenarios. Bivalirudin, a reversible direct thrombin inhibitor, has an onset time of 2 to 4 minutes and half-life of 25 minutes, is eliminated mainly by a proteolytic mechanism, does not require antithrombin III for effect, and is nonimmunogenic. The considerations for extracorporeal circulation are peculiar with its use, and this article outlines the aspects of initiating, maintaining, and terminating cardiopulmonary bypass and extracorporeal membrane oxygenation with bivalirudin as the anticoagulant.
Truncus Arteriosus with Interrupted Aortic Arch: Aortic Arch Reconstruction Without Circulatory Arrest
Authors: V. Bharath , Hote Milind Padmakar , Manjusha CH Naga Sai
Published: June 2022

Truncus arteriosus (TA) with interrupted aortic arch (IAA) is a rare congenital cardiac anomaly. Traditionally, IAA would require period of deep hypothermic circulatory arrest (DHCA) for aortic arch reconstruction. DHCA may cause myocardial depression and neuro-developmental dysfunction. IAA repair is presently being performed with hypothermic low-flow selective cerebral perfusion and distal body circulatory arrest. Even though this prevents cerebral adverse effects of DHCA, there is still risk to the spinal cord and kidneys.

Here, we describe the aortic arch reconstruction by maintaining the total body perfusion without any periods of circulatory arrest in a neonate with TA with IAA.
Rare case of Left Ventricular Hemangioma
Authors: CH Naga Sai Manjusha , V. Bharath , Hote Milind Padmakar
Published: June 2022

Cardiac tumors are rare in occurrence. Among them, primary cardiac tumors that too hemangiomas are further rare. They usually are asymptomatic and are detected incidentally. Preoperative diagnosis may not correlate with histopathologic diagnosis. We report such a rare case of left ventricular hemangioma presented to us with vague chest discomfort, which preoperatively was suspected to be rhabdomyoma or fibroma.
Linear Cephalometric Analysis of Pharynx at the Level of Epiglottis among Snorers and Nonsnorers: A Cross-Sectional Study
Authors: Rathod Ravi , Devadoss Vimal Joseph , Jadav Baliram , Ninan Reshmi Leila , Kanagasabapathy B. , Ramshad A.R. , Babu J. Suresh , Swarnalatha C. , Nayyar Abhishek Singh
Published: June 2022

Aim Snoring, which falls within the spectrum of sleep-related breathing disorders, is considered to be one of the common symptoms of airway obstruction. Lateral cephalometric analysis is an effective way of diagnosing airway obstruction by evaluating skeletal and soft tissue abnormalities in patients with sleep-disordered breathing (SDB). The present study was planned to analyze the pharyngeal space among snorers and nonsnorers in the retroglossal region and in the region of hypopharynx at the level of epiglottis.

Materials and Methods The present cross-sectional study included a total of 60 individuals who were grouped into snorers and nonsnorers based on their answers for the study questionnaire related to snoring. Digital lateral cephalograms were taken for all maintaining the exposure parameters while Digora software was used for measurements related to the soft tissue parameters. The two significant soft tissue parameters analyzed were the distance of epiglottis from the tip of the soft palate, the retroglossal length, and the distance of posterior pharynx from the tip of the epiglottis, the pharyngeal space.

Statistical Analysis The statistical analysis was done using Statistical Package for Social Sciences (SPSS) version 17.0 (SPSS Inc., Chicago, Illinois, United States) while paired t-test was used for intergroup analysis. A p-value of < 0.05 was considered statistically significant.

Results The mean retroglossal length was found to be 25.52 mm among the snorers and 23.70 mm among the nonsnorers. In case of pharyngeal space, a mean of 8.54 mm was recorded among the snorers whereas among the nonsnorers, the respective mean value of 10.16 mm was observed.

Conclusion In the present study, pharyngeal space was found to be less at the level of the tip of epiglottis among the snorers compared with nonsnorers which can be attributed to be one of the significant reasons behind snoring and obstructive sleep apnea syndrome.
Modeling helps fill knowledge gap in plasma-in-liquid streamer physics
Authors: Ikenson Ben
Published: June 2022

Advancing the understanding and potential applications of nanosecond-pulsed plasmas in liquids
Model selection of chaotic systems from data with hidden variables using sparse data assimilation
Authors: Ribera H. , Shirman S. , Nguyen A. V. , Mangan N. M.
Published: June 2022

Many natural systems exhibit chaotic behavior, including the weather, hydrology, neuroscience, and population dynamics. Although many chaotic systems can be described by relatively simple dynamical equations, characterizing these systems can be challenging due to sensitivity to initial conditions and difficulties in differentiating chaotic behavior from noise. Ideally, one wishes to find a parsimonious set of equations that describe a dynamical system. However, model selection is more challenging when only a subset of the variables are experimentally accessible. Manifold learning methods using time-delay embeddings can successfully reconstruct the underlying structure of the system from data with hidden variables, but not the equations. Recent work in sparse-optimization based model selection has enabled model discovery given a library of possible terms, but regression-based methods require measurements of all state variables. We present a method combining variational annealing—a technique previously used for parameter estimation in chaotic systems with hidden variables—with sparse-optimization methods to perform model identification for chaotic systems with unmeasured variables. We applied the method to ground-truth time-series simulated from the classic Lorenz system and experimental data from an electrical circuit with Lorenz-system like behavior. In both cases, we successfully recover the expected equations with two measured and one hidden variable. Application to simulated data from the Colpitts oscillator demonstrates successful model selection of terms within nonlinear functions. We discuss the robustness of our method to varying noise.
Early detection of lean blowout using recurrence network for varying degrees of premixedness
Authors: Bhattacharya Arijit , De Somnath , Mondal Sirshendu , Mukhopadhyay Achintya , Sen Swarnendu
Published: June 2022

Lean premixed combustors are highly susceptible to lean blowout flame instability, which can cause a fatal accident in aircrafts or expensive shutdown in stationary combustors. However, the lean blowout limit of a combustor may vary significantly depending on a number of variables that cannot be controlled in practical situations. Although a large literature exists on the lean blowout phenomena, a robust strategy for early lean blowout detection is still not available. To address this gap, we study a relatively unexplored route to lean blowout using a nonlinear dynamical tool, the recurrence network. Three recurrence network parameters: global efficiency, average degree centrality, and global clustering coefficient are chosen as metrics for an early prediction of the lean blowout. We observe that the characteristics of the time series near the lean blowout limit are highly dependent on the degree of premixedness in the combustor. Still, for different degrees of premixedness, each of the three recurrence network metrics increases during transition to lean blowout, indicating a shift toward periodicity. Thus, qualitatively, the recurrence network metrics show similar trends for different degrees of premixing showing their robustness. However, the sensitivities and absolute trends of the recurrence network metrics are found to be significantly different for highly premixed and partially premixed configurations. Thus, the results indicate that prior knowledge about (i) the degree of premixedness and (ii) the route to lean blowout may be required for accurate early prediction of the lean blowout. We show that the visible structural changes in the recurrence network can be linked to the changes in the recurrence network metrics, helping to better understand the dynamical transition to lean blowout. We observe the power law degree distribution of the recurrence network to break down close to the lean blowout limit due to the intermittent dynamics in the near-LBO regime.
Structure-based approach to identifying small sets of driver nodes in biological networks
Authors: Newby Eli , Tejeda Zañudo Jorge Gómez , Albert Réka
Published: June 2022

In network control theory, driving all the nodes in the Feedback Vertex Set (FVS) by node-state override forces the network into one of its attractors (long-term dynamic behaviors). The FVS is often composed of more nodes than can be realistically manipulated in a system; for example, only up to three nodes can be controlled in intracellular networks, while their FVS may contain more than 10 nodes. Thus, we developed an approach to rank subsets of the FVS on Boolean models of intracellular networks using topological, dynamics-independent measures. We investigated the use of seven topological prediction measures sorted into three categories—centrality measures, propagation measures, and cycle-based measures. Using each measure, every subset was ranked and then evaluated against two dynamics-based metrics that measure the ability of interventions to drive the system toward or away from its attractors: To Control and Away Control. After examining an array of biological networks, we found that the FVS subsets that ranked in the top according to the propagation metrics can most effectively control the network. This result was independently corroborated on a second array of different Boolean models of biological networks. Consequently, overriding the entire FVS is not required to drive a biological network to one of its attractors, and this method provides a way to reliably identify effective FVS subsets without the knowledge of the network dynamics.
Manipulating molten pool dynamics during metal 3D printing by ultrasound
Authors: Yang Zhichao , Wang Shuhao , Zhu Lida , Ning Jinsheng , Xin Bo , Dun Yichao , Yan Wentao
Published: June 2022

Ultrasound-assisted direct energy deposition (UADED) attracts increasing attention due to its capability to tailor the grain structure. However, the involved molten pool dynamics, particularly the complex interaction of ultrasound-flow-solidification, remain unclear to date, which hinders quantitative prediction and regulation of the microstructures and mechanical properties of UADED components. Here, in situ high-speed imaging and high-fidelity multi-physics modeling are leveraged to investigate flow characteristics and liquid-to-solid transformation in UADED for Inconel 718. The inertial force activated by ultrasound is revealed to drive the molten pool to flow forward and backward along the vibration direction, resulting in poor surface quality. A hybrid deposition strategy is developed to minimize ultrasound-induced defects and produce superior microstructure with alternating coarse- and fine- grains. Such a layered microstructure results in 28% and 15% improvement in the yield strength and ultimate tensile strength compared to the counterpart by additive manufacturing without ultrasound. This work provides unprecedented understanding into the molten pool dynamics in the UADED process as well as valuable guidance to manipulate molten pool flow.
Collagen-based shape-memory biocomposites
Authors: Lee JiUn , Kim GeunHyung
Published: June 2022

Shape-memory hydrogels (SMHs) have been used for various biomedical applications, such as injectable scaffolds in noninvasive procedures and as carriers for drugs and stem cells. However, most SMH studies have investigated properties related to shape recovery rather than bioactivities governed by hydrogel micro/nanostructure. In this study, one of the main structural proteins in tissues and organs, collagen, was incorporated into SMHs, and by varying the fabrication procedure, two different collagen-based SMHs were obtained. The first was a collagen Cryo-gel that could immediately recover its programmed shape. The second was a fibrous collagen gel (F-gel) fabricated by collagen fibrillation that required more time for recovery but possessed a much higher shape fixity ratio and better supported cell adhesion and growth in vitro. To combine the advantages of the two hydrogels, we fabricated a new collagen-based biocomposite that incorporated fibrillated collagen and photo-crosslinkable methacrylated collagen (Col-ma). A collagen/Col-ma ratio of 5:5 was the most favorable for shape recovery and cellular activity.
A construction and training data correction method for deep learning turbulence model of Reynolds averaged Navier–Stokes equations
Authors: Zhang Shuming , Li Haiwang , You Ruquan , Kong Tinglin , Tao Zhi
Published: June 2022

This paper aims at proposing a data-driven Reynolds Averaged Navier–Stokes (RANS) calculation model based on physically constrained deep learning. Using the standard k − ɛ model as the template, part of the source terms in the ɛ equation is replaced by the deep learning model. The simulation results of this new model achieve a high error reduction of 51.7% compared to the standard k − ɛ model. To improve the generality, the accuracy, and the convergence for the undeveloped flow, this paper focuses on optimizing the training process and introducing a data correction method named “coordinate” technology. For the training dataset, the k-field and ɛ-field are automatically corrected by using this technology when the flow state deviates from the theoretical estimation of the standard k − ɛ model. Based on the coordinate technology, a source term of the equation is built by deep learning, and the simulation error is reduced by 6.2% compared to the uncoordinated one. The results confirm that the coordinate technology can effectively adapt to the undeveloped flow where the standard k − ɛ model is not suited and improve the accuracy of the data-driven RANS modeling when dealing with complex flows.
Synchronized time tagger for single-photon detection in one- and two-dimension quantum experiments
Authors: Ye Runchuan , Lin Xue , Zhou Feifei , Dai Yulin , Hu Qidi , Li Xining , Xie Guangjun , Xu Nanyang
Published: June 2022

We report a synchronized time tagger based on a field-programmable-gate-array chip for one- or two-dimensional quantum experiments that require precise single-photon detections. The time tagger has a 9.2 ps single-shot root-mean-square precision and is equipped with a 1 GB dynamic memory for data storage. Because the relationship between the control parameter and acquired data is guaranteed by using hardware synchronization, the experiment can be performed much faster than conventional schemes that are based on software synchronization. With this technique, an improvement of up to 61.3% in efficiency is observed in a typical nitrogen-vacancy center quantum experiment. We further show advanced optical features of the center using the detected high-resolution photon-arrival information and provide detailed electrical benchmarking of the device. This technique could be easily extended to other quantum control systems.
Impact of gaps on the flow statistics in an emergent rigid canopy
Authors: Ranjan Pallav , Mittal Ketan , Chamorro Leonardo P. , Tinoco Rafael O.
Published: June 2022

High-resolution large eddy simulations and complementary laboratory experiments using particle image velocimetry were performed to provide a detailed quantitative assessment of flow response to gaps in cylinder arrays. The base canopy consists of a dense array of emergent rigid cylinders placed in a regular staggered pattern. The gaps varied in length from Δg/d=4 to 24, in intervals of 4d, where d is the diameter of the cylinders. The analysis was performed under subcritical conditions with Froude numbers Fr∈[0.08,0.2] and bulk Reynolds numbers Re∈[0.8, 2]×104. Results show that the gaps affect the flow statistics at the upstream and downstream proximity of the canopy. The affected zone was Δx/d≈5 for the mean flow and Δx/d≈3 for the second-order statistics. Dimensionless time-averaged streamwise velocity within the gap exhibited minor variability with gap spacing; however, in-plane turbulent kinetic energy, k, showed a consistent decay rate when normalized with that at x/d≥1 from the beginning of the gap. The emergent canopy acts as a passive turbulence generator for the gap flow for practical purposes. The streamwise dependence of k follows an exponential trend within 1≤x/d≲2.5 and transitions to a power-law at x/d≥4. The substantially lower maximum values of k within the gap compared to k within the canopy evidence a limitation of gap measurements representative of canopy flow statistics. We present a base framework for estimating representative in-canopy statistics from measurements in the gap.
Stability of heteroclinic cycles in ring graphs
Authors: Postlethwaite Claire M. , Sturman Rob
Published: June 2022

Networks of interacting nodes connected by edges arise in almost every branch of scientific inquiry. The connectivity structure of the network can force the existence of invariant subspaces, which would not arise in generic dynamical systems. These invariant subspaces can result in the appearance of robust heteroclinic cycles, which would otherwise be structurally unstable. Typically, the dynamics near a stable heteroclinic cycle is non-ergodic: mean residence times near the fixed points in the cycle are undefined, and there is a persistent slowing down. In this paper, we examine ring graphs with nearest-neighbor or nearest-m-neighbor coupling and show that there exist classes of heteroclinic cycles in the phase space of the dynamics. We show that there is always at least one heteroclinic cycle that can be asymptotically stable, and, thus, the attracting dynamics of the network are expected to be non-ergodic. We conjecture that much of this behavior persists in less structured networks and as such, non-ergodic behavior is somehow typical.
Plasma enhanced chemical vapor deposition of p-type Cu2O from metal organic precursors
Authors: Gomersall D. E. , Flewitt A. J.
Published: June 2022

The scope of this work was to optimize the reactant delivery parameters for the plasma enhanced chemical vapor deposition (PECVD) of p-type Cu2O films from Cu(hfac)(tmvs), with the aim to explore an alternative to other large-area deposition techniques such as sputtering. While n-type metal oxide semiconductors such as amorphous indium gallium zinc oxide have now been developed and offer significantly improved device performance over hydrogenated amorphous silicon, with devices achieving mobilities >10cm2(Vs)−1, there is still an absence of good p-type inorganic semiconductors that provide similar performance. Cu2O is a promising p-type metal oxide, but there remain limitations on the industrial scalability of some of the deposition processes demonstrated so far. PECVD has been scaled for uniform deposition on generation 10 display glass (2.88×3.13m2) and so provides a viable alternative. The Cu2O films deposited in this work achieved a Hall mobility of ∼1cm2(Vs)−1 and were stable over a period of months. Contrary to previous reports of an “incubation” period, the initial growth rate during and immediately following nucleation was (∼40 nm/pulse) 10 times greater than the steady state growth (∼4 nm/pulse) achieved later in the deposition. Topographical scaling methods and fractal analysis of the film surface morphology using atomic force microscopy, at different stages during growth development, link this shift to a regime transition from growth dominated by surface diffusion to volume diffusion.
Microstructural evolution and precipitation in γ-LiAlO2 during ion irradiation
Authors: Jiang Weilin , Kovarik Libor , Zhu Zihua , Varga Tamas , Bowden Mark E. , Matthews Bethany E. , Hu Zhihan , Shao Lin , Senor David J.
Published: June 2022

Polycrystalline γ-LiAlO2 pellets were sequentially irradiated with 120 keV He+ and 80 keV D2+ ions to the fluences of 1 × 1017 and 2 × 1017 (He+ + D+)/cm2 at 573 K. Additional irradiation was performed to a fluence of 2 × 1017 (He+ + D+)/cm2 at 773 K. The irradiated pellets were characterized using scanning transmission electron microscopy, time-of-flight secondary ion mass spectrometry, and grazing incidence x-ray diffraction. Lattice damage, amorphization, and fractures are observed with no evidence for the formation of secondary-phase precipitates in the pellets irradiated up to an ion fluence of 2 × 1017 (He+ + D+)/cm2 at 573 K. In contrast, faceted precipitates with sizes larger than 100 nm formed in a pellet irradiated to 2 × 1017 (He+ + D+)/cm2 at 773 K. Analyses of the diffraction and composition data suggest that the precipitates have a spinel-type structure, likely a non-stoichiometric LiAl5O8 with Li depletion. This could be an intermediate phase with Li atoms at the octahedral and possibly tetrahedral sites as well. It is speculated that as the dose increases, Li loss will continue and the precipitates will approach a composition of alumina primarily in phases of α-Al2O3 and amorphized Al2O3.
A dissipative nonlinear Schrödinger model for wave propagation in the marginal ice zone
Authors: Alberello A. , Părău E. I.
Published: June 2022

Sea ice attenuates waves propagating from the open ocean. Here, we model the evolution of energetic unidirectional random waves in the marginal ice zone with a nonlinear Schrödinger equation, with a frequency dependent dissipative term consistent with current model paradigms and recent field observations. The preferential dissipation of high frequency components results in a concurrent downshift of the spectral peak that leads to a less than exponential energy decay, but at a lower rate compared to a corresponding linear model. Attenuation and downshift contrast nonlinearity and nonlinear wave statistics at the edge tend to Gaussianity farther into the marginal ice zone.
A steep-slope tellurium transistor with a native voltage amplifying threshold switch
Authors: Wang Xinxin , Li Huanglong
Published: June 2022

What precludes lowering the supply voltage and overall power consumption of the transistor is the infamous Boltzmann tyranny, a fundamental thermionic limit preventing the subthreshold slope (SS) of the transistor from being lower than 60 mV dec−1 at room temperature (RT). Internal voltage amplification through the use of an additional threshold switch (TS) serially connected to the transistor channel has been shown to be highly effective to break the Boltzmann barrier. This approach, however, is typically heterogeneous by employing TS materials that are foreign to the transistor. Recently, semiconducting tellurium (Te) has gained considerable research interest for its use as an emerging low-dimensional p-type channel material with high hole mobility, air-stability, and the ability to be processed at near ambient temperature. In this work, we unveil a hidden advantage of Te for a steep-slope transistor in which Te serves as the channel material and the TS material at the same time. In a homogeneous and compact device architecture, RT-SS lower than 30 mV dec−1 can be achieved. This is enabled by a combination of unique electrical–electrochemical–thermal properties in Te. This work augments the functionality of Te and provides a low-power transistor solution.
Verification of morphological and physical properties for the development of a lung substitute phantom using microspheres
Authors: Fuse Hiraku , Otsuki Shohei , Fujisaki Tatsuya , Yasue Kenji , Hanada Koichi , Tomita Fumihiro , Abe Shinji
Published: June 2022

This paper proposes a new concept of phantom development, along with the utilization of new materials that can reproduce lung morphology and density. A lung substitute phantom using microspheres was fabricated; then, its dosimetric utility in radiotherapy was investigated, during which the density was adjusted to closely resemble the morphology of the actual human lung. Microspheres were used to reproduce alveoli, which are the main components of the lung. By changing the ratio of urethane, which is commonly used in soft tissue phantoms, to microspheres, we reproduced the density change of the lungs due to respiration. Here, we fabricated two slab-like lung substitutes to emulate commercially used phantoms. Although there is room for improvement in terms of practicality, the substitutes were easy to fabricate. Microscopic observation of the cut surface of the phantoms showed that the morphology of the phantoms mimicked the alveoli more faithfully than commercial phantoms. Furthermore, to compensate for the energy-independent mass attenuation and mass collision inhibition ability required by the tissue substitute phantom, we examined the physical properties of the phantom and confirmed that there was negligible energy dependence.
Effect of soft and hard x-rays on shock propagation, preheating, and ablation characteristics in pure and doped Be ablators
Authors: Ghosh Karabi , Mishra Gaurav
Published: June 2022

Detailed investigations are carried out on shock, preheat, and ablation characteristics in x-ray driven beryllium based targets, a candidate ablator material for many inertial confinement fusion studies due to its high mass ablation rate. The study involves extensive radiation hydrodynamic simulations performed on pure and 1% copper doped beryllium foils irradiated by a temperature drive source consisting of both Planckian and Gaussian distributions with peaks lying in soft and hard x-ray regions, respectively. The results of steady state x-ray driven ablation and radiant heat exchange in a sub-critical shock are extended to a non-Planckian source. Based on that, new scaling relations are proposed for shock velocity, shock breakout temperature, maximum preheat temperature, and mass ablation rate with the temperature (120−200 eV) and the fraction of total energy density due to Gaussian distribution (0−0.25) of the incident drive. All parameters increase with drive temperature strength, but the presence of hard x rays does not affect them uniformly. Among all, preheat and shock breakout temperature exhibit a strong dependence on fraction of hard x rays present in the drive spectrum. The effect of doping translates into a pronounced decrease in preheat and shock breakout temperature, while mass ablation rate reduces marginally. The resulting variations in different parameters are explained on the basis of distribution of total extinction coefficient over the spectral form of an incident drive source.
Synergistic antimicrobial effects of atmospheric pressure non-thermal argon plasma and ciprofloxacin antibiotic against multi-drug resistant P. aeruginosa biofilm
Authors: Khosravi S. , Jafari S. , Zamani H. , Nilkar M.
Published: June 2022

Bacterial biofilm formation is regarded as the major cause of infection development, therapeutic failure, and antibiotic resistance. This study aimed to assess the synergistic antibiofilm potential of an atmospheric-pressure non-thermal argon plasma and ciprofloxacin (Cip) against multi-drug-resistant Pseudomonas aeruginosa. Bacterial biofilms were pre-treated with the non-thermal Ar-plasma and subsequently treated with Cip antibiotic. Then, the bacterial biofilm formation level and cell viability were investigated using crystal violet staining, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide, SEM, and fluorescence microscopy, respectively. It was found that a short-time (a few seconds) pretreating with Ar-plasma not only reduced bacterial biofilm formation but also significantly decreased the viability of the cells within the biofilm matrix. According to the results, treating with Cip alone reduced bacterial biofilms by 32%, while pretreatment with Ar-plasma for 5, 10, 30, 60, and 90 s and subsequent treatment with Cip reduced bacterial biofilms by 76%, 79%, 81%, 75%, and 88%, respectively. In addition, the viability of bacterial cells within the biofilm matrix reduced to 66% in Cip treated cells, while pretreating with Ar-plasma for 5, 10, 30, 60, and 90 s and then treating with Cip significantly decreased cell viability to 28%, 25%, 21%, 23%, and 15%, respectively. This concept opens a promising approach for the treatment of drug-resistant bacteria for decontamination of heat-sensitive materials and human tissues based on the combination of atmospheric-pressure non-thermal Ar-plasma and antibiotics.
Numerical simulation of the wake dynamics of the pumpjet propulsor in oblique inflow
Authors: Huang Qiaogao , Qin Denghui , Pan Guang
Published: June 2022

A numerical analysis based on detached eddy simulations is conducted to investigate vortex dynamics of a pre-swirl pumpjet propulsor (PJP) in oblique inflow. In this paper, the working conditions of PJP operating in axisymmetric flow and drift with two angles (10° and 20°) are considered. The effects of incidence α and propeller loading on the wake dynamics of PJP as well as the mechanism leading to its destabilization are discussed. The results show that high hydrodynamic efficiency loss is found for PJP operating in drift. In addition, a different “secondary vortex structure” caused by the duct is found for PJP in both axisymmetric and oblique flow conditions. The instability mechanism of tip vortices shows obvious asymmetry. On the leeward side, it is dominated by the interaction caused by the duct-induced vortex, while it is dominated by the secondary vortices on the windward side. Furthermore, the fluctuation frequency of tip vortex for PJP is characterized by the rotor blade-passing frequency and the stator blade-passing frequency. In addition, the hub rotation frequency is important in oblique flow conditions.
Impact of electron transport models on capillary discharge plasmas
Authors: Diaw A. , Coleman S. J. , Cook N. M. , Edelen J. P. , Hansen E. C. , Tzeferacos P.
Published: June 2022

Magnetohydrodynamics (MHD) can be used to model capillary discharge waveguides in laser-wakefield accelerators. However, the predictive capability of MHD can suffer due to poor microscopic closure models. Here, we study the impact of electron heating and thermal conduction on the capillary waveguide performance as part of an effort to understand and quantify uncertainties in modeling and designing next-generation plasma accelerators. To do so, we perform two-dimensional high-resolution MHD simulations using an argon-filled capillary discharge waveguide with three different electron transport coefficients models. The models tested include (i) Davies et al., (ii) Spitzer, and (iii) Epperlein–Haines (EH). We found that the EH model overestimates the electron temperature inside the channel by over 20% while predicting a lower azimuthal magnetic field. Moreover, the Spitzer model, often used in MHD simulations for plasma-based accelerators, predicts a significantly higher electron temperature than the other models suggest.
Improving time series prediction accuracy for the maxima of a flow by reconstructions using local cross sections
Authors: Hirata Yoshito , Shiro Masanori
Published: June 2022

Despite a long history of time series analysis/prediction, theoretically few is known on how to predict the maxima better. To predict the maxima of a flow more accurately, we propose to use its local cross sections or plates the flow passes through. First, we provide a theoretical underpinning for the observability using local cross sections. Second, we show that we can improve short-term prediction of local maxima by employing a generalized prediction error, which weighs more for the larger values. The proposed approach is demonstrated by rainfalls, where heavier rains may cause casualties.
Stretchable conductive nanocomposites and their applications in wearable devices
Authors: Park Chansul , Kim Min Su , Kim Hye Hyun , Sunwoo Sung-Hyuk , Jung Dong Jun , Choi Moon Kee , Kim Dae-Hyeong
Published: June 2022

Recently, highly conductive polymer nanocomposites, particularly soft polymer nanocomposites, have received extensive attention as promising material candidates for wearable devices. Compared with the cases of the wearable devices based on conventional rigid electronic materials, the wearable devices based on polymer nanocomposites exhibit excellent conformal contacts with the skin due to the soft mechanical properties of these nanocomposites; therefore, soft polymeric nanocomposites can be applied to stretchable wirings, electrodes, and sensor units in various on-skin electronics. The types of polymers and nanofillers used for the synthesis of these nanocomposites are critical factors determining the properties of polymer nanocomposites. The overall physical properties of nanocomposites depend on the type of polymer used, whereas the electrical properties of nanocomposites are governed by the type of nanofiller employed. Herein, we review the latest studies on the polymer nanocomposites constructed using different polymers and nanofillers that are applied to wearable devices. We have classified the polymers into non-elastic polymers, hydrogels, chemically crosslinked elastomers, and physically crosslinked elastomers and the nanofillers into C, liquid metal, Ag, Au, and other emerging nanomaterials. Detailed characteristics, fabrication methods, applications, and limitations of these nanocomposites are reviewed. Finally, a brief outlook for future research is provided.
Partial locking in phase-oscillator populations with heterogenous coupling
Authors: Xu Can , Wu Yonggang , Zheng Zhigang , Tang Longkun
Published: June 2022

We consider a variant of the mean-field model of coupled phase oscillators with uniform distribution of natural frequencies. By establishing correlations between the quenched disorder of intrinsic frequencies and coupling strength with both in- and out-coupling heterogeneities, we reveal a generic criterion for the onset of partial locking that takes place in a domain with the coexistence of phase-locked oscillators and drifters. The critical points manifesting the instability of the stationary states are obtained analytically. In particular, the bifurcation mechanism of the equilibrium states is uncovered by the use of frequency-dependent version of the Ott–Antonsen reduction consistently with the analysis based on the self-consistent approach. We demonstrate that both the manner of coupling heterogeneity and correlation exponent have influence on the emergent patterns of partial locking. Our research could find applicability in better understanding the phase transitions and related collective phenomena involving synchronization control in networked systems.
Phonon thermal transport in copper: The effect of size, crystal orientation, and grain boundaries
Authors: Sæther Sandra , Erichsen Merete Falck , Xiao Senbo , Zhang Zhiliang , Lervik Anders , He Jianying
Published: June 2022

In electronic devices at the micro- and nanoscale, thermal management is vital. At such small sizes, crystal orientation, grain boundaries, and even the size itself can play an important role in the thermal transport and need to be taken into careful consideration when devices are designed. In this article, we perform computational experiments using non-equilibrium molecular dynamics simulations to evaluate the effect of size, orientation, and grain boundaries on the phonon thermal transport of copper. In addition, we compare the results obtained from the rescale and Langevin thermostat procedures. We find that the contribution of phonons to the total thermal conductivity in copper increases as the size decreases. Furthermore, the Σ5(210)[001] twist grain boundary is found to have a significant effect on the thermal transport of a bi-crystalline copper system when the grains are 15 nm. No such effect is found for the Σ3(112)[110] twin boundary. The effect of crystal orientation on the thermal conductivity is also studied, and no discerned effect can be observed. It is found that the Langevin thermostat leads to an over-estimation of the thermal conductivities at smaller scales and should be used with caution.
Revisiting the Siegert relation for the partially coherent regime of nanolasers
Authors: Drechsler M. , Lohof F. , Gies C.
Published: June 2022

The Siegert relation connects the first- and second-order coherence properties of light. Although strictly valid only in the thermal regime and in the absence of correlations, this relation is routinely extended to the partially coherent regime in the study of high-β nanolasers, where it aids in the identification of the lasing threshold. We re-evaluate the use of a generalized Siegert relation in different device regimes. A full two-time quantum-optical theory is derived as a reference for obtaining first- and second-order correlation functions g(1)(τ) and g(2)(τ) in the steady state. We find that even in the partially coherent regime, the generalized Siegert relation is well suited as an approximation to g(2)(τ) as long as emitter correlations are negligible but does not apply well in the quantum regime of few-emitter nanolasers or to devices featuring sub- and super-radiant emission.
Dynamic mode decomposition with core sketch
Authors: Ahmed Shady E. , Dabaghian Pedram H. , San Omer , Bistrian Diana A. , Navon Ionel M.
Published: June 2022

With the increase in collected data volumes, either from experimental measurements or high fidelity simulations, there is an ever-growing need to develop computationally efficient tools to process, analyze, and interpret these datasets. Modal analysis techniques have gained great interest due to their ability to identify patterns in the data and extract valuable information about the system being considered. Dynamic mode decomposition (DMD) relies on elements of the Koopman approximation theory to compute a set of modes, each associated with a fixed oscillation frequency and a decay/growth rate. Extracting these details from large datasets can be computationally expensive due to the need to implement singular value decomposition of the input data matrix. Sketching algorithms have become popular in numerical linear algebra where statistical theoretic approaches are utilized to reduce the cost of major operations. A sketch of a matrix is another matrix, which is significantly smaller, but still sufficiently approximates the original system. We put forth an efficient DMD framework, SketchyDMD, based on a core sketching algorithm that captures information about the range and corange (their mutual relationship) of input data. The proposed sketching-based framework can accelerate various portions of the DMD routines, compared to classical methods that operate directly on the raw input data. We conduct numerical experiments using the spherical shallow water equations as a prototypical model in the context of geophysical flows. We show that the proposed SketchyDMD is superior to existing randomized DMD methods that are based on capturing only the range of the input data.
Peculiarities of planar shockwave interaction with air–water interface and solid target
Authors: Maler D. , Efimov S. , Liverts M. , Theocharous S. , Strucka J. , Yao Y. , Proud W. , Rack A. , Lukic B. , Bland S. N. , Krasik Ya. E.
Published: June 2022

We present the results of the research on underwater electrical explosion of planar copper wire arrays, accompanied by the generation of a planar shock, using the synchrotron-based phase-contrast radiography imaging capabilities of the ID19 beamline at the European Synchrotron Radiation Facility. It is shown that the interaction of a strong shock with an air–water interface leads to additional acceleration of the wire expansion due to a rarefaction wave along with the emergence of micro-jets. In the case of a target placed above the array, we observed the formation of a cavity between the array and the target due to the interaction of two rarefaction waves. The results of two-dimensional hydrodynamic simulations of the wire explosion and the interaction of the generated shock with the water–air and water-target interfaces showed good agreement with experimental results.
Capillary condensation of saturated vapor in a corner formed by two intersecting walls
Authors: Benilov E. S.
Published: June 2022

The dynamics of saturated vapor between two intersecting walls is examined. It is shown that, if the angle ϕ between the walls is sufficiently small, the vapor becomes unstable, and spontaneous condensation occurs in the corner, similar to the so-called capillary condensation of vapor into a porous medium. As a result, an ever-growing liquid meniscus develops near the corner. The diffuse-interface model and the lubrication approximation are used to demonstrate that the meniscus grows if and only if ϕ+2θ<π, where θ is the contact angle corresponding to the fluid/solid combination under consideration. This criterion has a simple physical explanation: if it holds, the meniscus surface is concave—hence, the Kelvin effect causes condensation. Once the thickness of the condensate exceeds by an order of magnitude the characteristic interfacial thickness, the volume of the meniscus starts to grow linearly with time. If the near-vertex region of the corner is smoothed, the instability can be triggered off only by finite-size perturbations, such that it includes enough liquid to cover the smoothed area by a microscopically thin liquid film.
Simultaneous streamwise and cross-stream oscillations of a diamond oscillator at low Reynolds numbers
Authors: Sourav Kumar , Yadav Pavan Kumar , Tallapragada Phanindra , Kumar Deepak
Published: June 2022

A two-dimensional stabilized space-time finite-element-based in-house solver is used to explore flow around an elastically mounted rigid diamond oscillator undergoing undamped vortex-induced vibrations in transverse and stream-wise directions simultaneously. The computations are carried over a reduced velocity (U*) range of 1–12 keeping the Reynolds number (Re) and the mass ratio (m*) fixed at 100 and 10, respectively. In the current investigation, a five-branch response behavior with the presence of an “upper branch” is identified, which is absent for transverse-only oscillations. A shift in normalized time-averaged phase difference (ϕ/π) from 0 to 1 is related to the transition from the upper to the lower branch. The non-dimensional oscillation frequencies in both streamwise and cross-stream directions (Fx and Fy, respectively) collapse on the upper branch, matching the oscillator's non-dimensional natural frequency (FN). This leads to periodic single-looped “raindrop-shaped” cylinder trajectories. On this branch, the vortex-shedding mode is asymmetric, and the mean lift is non-zero (Clavg≠0). For all other response branches, Clavg≈0 and the vortex-shedding modes are symmetric. The presence of multiple frequencies in the in-line oscillations makes the initial branch quasi-periodic, whereas all other response branches are periodic. The addition of in-line motion modifies the fluid loading on the oscillator significantly.
First-principles study on δ-Pu surface stability
Authors: Xiong Qing , Wang Jintao , Hang Guiyun , Yu Wenli , Wang Tao
Published: June 2022

δ-Pu has been widely used due to its outstanding material properties, and surface stability is essential for studying its surface corrosion mechanism. In this work, δ-Pu and its surface stability were analyzed based on first-principles calculations. The third-order Birch–Murnaghan equation of state fitted the calculated data for the δ-Pu cell, and the lattice constant of equilibrium structure was obtained. By constructing the surface models of three conventional crystal directions, (100), (110), and (111), the surface structure was optimized based upon the Quasi-Newton method, and the surface energy and electronic structure were calculated. The results show that the (110) surface energy of δ-Pu was 0.103 eV/Å2, and the (111) surface energy of δ-Pu was 0.052 eV/Å2. Thus, the d-band center of the (111) plane is farther away from the Fermi level than (100) and (110). Among the three typical crystal orientation planes, the surface energy and electronic structure show that the (111) plane was the most stable crystal orientation plane of δ-Pu.
Carbon dioxide removal is suddenly obtaining credibility and support
Authors: Kramer David
Published: June 2022

The question about carbon extraction is no longer if it will be needed, but whether it can be scaled up quickly enough.