bluuebunny/crossref_metadata_2025 huggingface dataset:
Discovery of modulators for the PD-1/PD-L1 interaction by molecular simulation and bioassay
Authors: Li Guangping , Guo Haiqiong , Zhao Linan , Feng Huixian , He Huawei , Chen Yan , Wang Yuanqiang , Lin Zhihua
Published: September 2021

PD-1-targeted discovery of modulators by virtual screening, molecular docking, surface plasmon resonance binding assay and T-cell activation assay.
Synthesis and solution isomerization of water-soluble Au9nanoclusters prepared by nuclearity conversion of [Au11(PPh3)8Cl2]Cl
Authors: Ndugire William , Yan Mingdi
Published: September 2021

This work reports a new method for the synthesis of water-soluble Au9nanoclusters and a strikingly visible temperature- and pH-dependent isomerization.
Isolation of the Au145(SR)60X compound (R = n-butyl, n-pentyl; X = Br, Cl): novel gold nanoclusters that exhibit properties subtly distinct from the ubiquitous icosahedral Au144(SR)60 compound
Authors: Dainese Tiziano , Antonello Sabrina , Bonacchi Sara , Morales-Martinez Daniel , Venzo Alfonso , Black David M. , Mozammel Hoque M. , Whetten Robert L. , Maran Flavio
Published: September 2021

We isolated and characterized the thiolate-protected Au145 nanocluster. Au145 exhibits a behavior similar to that of Au144, but for its much more intense luminescence.
Self-assembly of peptide nanofibers for imaging applications
Authors: Jiang Qiaochu , Liu Xiaoyang , Liang Gaolin , Sun Xianbao
Published: September 2021

Self-assembly of peptide nanofibers shows significance in tumor/disease imaging applications.
Post-polymerization modification of polybenzoxazines with boronic acids supported by B–N interactions
Authors: Tsukamoto Yuki , Kida Jumpei , Aoki Daisuke , Otsuka Hideyuki
Published: September 2021

Polybenzoxazines (PBZs) were modified using the reactivity of their inherent bis(2-hydroxybenzyl)amine (BHBA) units toward boronic acids, RB(OH)2.
Rationalization of the mechanism and chemoselectivity of versatile Au-catalyzed reactions of diazoesters with allyl-functionalized sulfides, selenides, amines, or ethers by DFT
Authors: Gao Caicai , Cao Teng , Kirillov Alexander M. , Fang Ran , Yang Lizi
Published: September 2021

The origin of chemoselectivity and the mechanism of the title reactions were fully rationalized by density functional theory (DFT).
Direct evidence for distinct colour origins in ROY polymorphs
Authors: Warren Lisette R. , McGowan Evana , Renton Margaret , Morrison Carole A. , Funnell Nicholas P.
Published: September 2021

Alternative colour origins in ROY polymorphs are conclusively determined for the first time, using high-pressure diffraction and hybrid DFT.
Serum markers change for intraocular metastasis in renal cell carcinoma
Authors: Sun Tie , Tang Jing , Pan Yi-Cong , Yu Chen-Yu , Li Biao , Zhang Li-Juan , Shu Hui-Ye , Ge Qian-Min , Shao Yi
Published: September 2021

Objective: Renal cell carcinoma is prone to early metastasis. In general, intraocular metastasis (IOM) is not common. In the present study, we studied the relationship between different biochemical indicators and the occurrence of IOM in renal cancer patients, and identified the potential risk factors.

Methods: A retrospective analysis of the clinical data of 214 patients with renal cell carcinoma from October 2001 to August 2016 was carried out. The difference and correlation of various indicators between the two groups with or without IOM was analyzed, and binary logistic regression analysis was used to explore the risk factors of IOM in renal cancer patients. The diagnostic value of each independent related factor was calculated according to the receiver operating curve (ROC).

Results: The level of neuron-specific enolase (NSE) in renal cell carcinoma patients with IOM was significantly higher than that in patients without IOM (P<0.05). There was no significant difference in alkaline phosphatase (ALP), hemoglobin (Hb), serum calcium concentration, α fetoprotein (AFP), carcinoembryonic antigen (CEA), CA-125 etc. between IOM group and non-IOM (NIOM) group (P>0.05). Binary logistic regression analysis showed that NSE was an independent risk factor for IOM in renal cell carcinoma patients (P<0.05). ROC curve shows that the factor has high accuracy in predicting IOM, and the area under the curve (AUC) is 0.774. The cut-off value of NSE was 49.5 U/l, the sensitivity was 72.2% and the specificity was 80.1%.

Conclusion: NSE concentration is a risk factor for IOM in patients with renal cell cancer. If the concentration of NSE in the patient’s body is ≥49.5 U/l, disease monitoring and eye scans should be strengthened.
Intelligent control of a single‐link flexible manipulator using sliding modes and artificial neural networks
Authors: Lima Gabriel da Silva , Porto Diego Rolim , de Oliveira Adilson José , Bessa Wallace Moreira
Published: September 2021

This letter presents a new intelligent control scheme for the accurate trajectory tracking of flexible link manipulators. The proposed approach is mainly based on a sliding mode controller for underactuated systems with an embedded artificial neural network to deal with modelling inaccuracies. The adopted neural network only needs a single input and one hidden layer, which drastically reduces the computational complexity of the control law and allows its implementation in low‐power microcontrollers. Online learning, rather than supervised offline training, is chosen to allow the weights of the neural network to be adjusted in real time during the tracking. Therefore, the resulting controller is able to cope with the underactuating issues and to adapt itself by learning from experience, which grants the capacity to deal with plant dynamics properly. The boundedness and convergence properties of the tracking error are proved by evoking Barbalat's lemma in a Lyapunov‐like stability analysis. Experimental results obtained with a small single‐link flexible manipulator show the efficacy of the proposed control scheme, even in the presence of a high level of uncertainty and noisy signals.
Modeling the scattering polarization of the solar Ca I 4227 Å line with angle-dependent partial frequency redistribution
Authors: Janett Gioele , Ballester Ernest Alsina , Guerreiro Nuno , Riva Simone , Belluzzi Luca , del Pino Alemán Tanausú , Bueno Javier Trujillo
Published: September 2021

Context. The correct modeling of the scattering polarization signals observed in several strong resonance lines requires taking partial frequency redistribution (PRD) phenomena into account. Modeling scattering polarization with PRD effects is very computationally demanding and the simplifying angle-averaged (AA) approximation is therefore commonly applied.

Aims. This work aims to assess the impact and the range of validity of the AA approximation with respect to the general angle-dependent (AD) treatment of PRD effects in the modeling of scattering polarization in strong resonance lines, with a focus on the solar Ca I 4227 Å line.

Methods. Spectral line polarization was modeled by solving the radiative transfer problem for polarized radiation, under nonlocal thermodynamic equilibrium conditions, taking PRD effects into account in static one-dimensional semi-empirical atmospheric models presenting arbitrary magnetic fields. The problem was solved through a two-step approach. In step 1, the problem was solved for the intensity only, considering a multilevel atom. In step 2, the problem was solved including polarization, considering a two-level atom with an unpolarized and infinitely sharp lower level, and fixing the lower level population calculated at step 1.

Results. The results for the Ca I 4227 Å line show a good agreement between the AA and AD calculations for the Q/I and U/I wings’ signals. However, AA calculations reveal an artificial trough in the line-core peak of the linear polarization profiles, whereas AD calculations show a sharper peak in agreement with the observations.

Conclusions. An AD treatment of PRD effects is essential to correctly model the line-core peak of the scattering polarization signal of the Ca I 4227 Å line. By contrast, in the considered static case, the AA approximation seems to be suitable to model the wing scattering polarization lobes and their magnetic sensitivity through magneto-optical effects.
HD 144941: the most extreme helium-strong star
Authors: Przybilla N. , Fossati L. , Jeffery C. S.
Published: September 2021

Since its discovery about 50 yr ago, HD 144941 has generally been classified as a peculiar member of the extreme helium (EHe) supergiant stars, a very rare class of low-mass hydrogen-deficient stars. We report the detection of a strong longitudinal magnetic field based on spectropolarimetry with FORS2 on the ESO VLT with surface-averaged longitudinal field strengths as large as −9 kG. This is further constrained by the detection of Zeeman splitting of spectral lines to a field strength of at least 15 kG, explaining the recent finding of surface spots for this star. The quantitative analysis of the stellar atmosphere based on a hybrid non-local thermodynamic equilibrium approach and new optical spectra yields an effective temperature of 22 000 ± 500 K, a logarithmic surface gravity of 4.20 ± 0.10, and a surface helium fraction of 0.950 ± 0.002 by number. While the metal abundances are about a factor of 10 sub-solar in absolute number, the metal-to-hydrogen ratios are typical of massive early-type stars, indicating that helium fallback in a weak, fractionated stellar wind in the presence of a magnetic field took place – the canonical mechanism for the formation of the helium-strong phenomenon. Both the spectroscopic and the Gaia EDR3 parallax imply HD 144941 to be a luminous massive star. Kinematically, we argue that HD 144941 has reached its high Galactic latitude as a runaway star. We conclude that instead of being a comparatively high-gravity low-mass EHe star, HD 144941 is by far the most extreme member of the magnetic massive helium-strong stars, with almost all atmospheric hydrogen substituted by helium.
Effect of multi-layer feeding of sized green pelletson bed permeability, structure and properties of fired pellets in straight grate induration furnace
Authors: Umadevi Tekkalakote , Sridhara Komala Shivanna , Raju Munukuntla , Basavaraja Maribasappanavar , Sanghamesh Desai , Rameshwar Sah , Singh Lokendraraj
Published: September 2021

Green pellets while indurating in a straight grate induration furnace, pass through different thermal treatments, namely drying, preheating, heating and cooling. The firing of the pellet bed is downdraft using Corex gas and cooling is updraft using ambient air. Coke breeze is used as solid fuel to supplies the necessary heat for uniform heating of the pellet. The physicochemical conditions prevailing in the indurating furnace, i.e., feeding rate, bed height, pellet size, position of the pellets in the bed, temperature, partial pressure of oxygen, amount of fuel, etc. have bearings on the phases and structures of the fired pellets across the core to the shell. The time difference between the reduction and oxidation of the pellet depends on the size of the pellet as well as position of the pellet in the bed. The pellet size as well as the position of the pellet in the furnace has a marked effect on the formation of different phases and microstructure. Usually, mixed pellets of different sizes varying from 8 to 16 mm pellets are fired in duration furnace. The study was aimed at to optimize the pellet bed with different size range of pellets put in layers to make uniform firing and cooling of the pellets throughout the bed to achieve desired micro-structure and properties. The green pellets were divided into three sizes as A − coarse (–16 + 12.5 mm), B − medium (–12.5+10 mm) and C − small (–10 + 8 mm). The bed permeability of pellet plant induration furnace was 91.7JPU (Japanese Permeability Unit). Except permeability of pellet bed with single layer of smaller size pellets (C-C-C), the bed permeability with three layers, two layers & single layer of different size pellets was similar or greater than the bed permeability of pellet plant. From the results of basket trials conducted at pellet plant, it was found that the layer wise pellets like B-A-C, CA-B, AB-C and B-B-B resulted in higher Tumbler Index (TI) and Cold Crushing Strength (CCS) compared to other different size pellets as layer due to better slag bonding and lower pellet porosity. These pellets were exposed to optimum firing temperature as well as the cooling process with the presence of sufficient oxygen for the conversion of magnetite to hematite.
In vitro anthelmintic activity of an aqueous extract of Glycyrrhiza glabra and of glycyrrhetinic acid against gastrointestinal nematodes of small ruminants
Authors: Maestrini Michela , Molento Marcelo Beltrão , Forzan Mario , Perrucci Stefania
Published: September 2021

This study evaluated the in vitro anthelmintic activity of a liquorice (Glycyrrhiza glabra) root aqueous extract and of glycyrrhetinic acid at 30, 10, 5, 1, and 0.5 mg/mL against sheep gastrointestinal nematodes (GINs), using the egg hatch test (EHT), the larval development test (LDT), and the larval migration inhibition test (LMIT). The compounds were applied on a mixture of GIN eggs and larvae, mainly Trichostrongylus spp. and Teladorsagia/Ostertagia spp. Cytotoxicity assays were also performed. In the EHT, both candidates showed significant concentration-dependent efficacy and were significantly more effective (p < 0.001) at the highest concentrations (30 and 10 mg/mL) than the lowest ones. In the LDT, only G. glabra showed a concentration-dependent effect (R2 = 0.924), but glycyrrhetinic acid (R2 = 0.910) had significantly higher efficacy than G. glabra root extract. Moreover, the efficacy of glycyrrhetinic acid at 30, 10, and 5 mg/mL was significantly higher (p < 0.001) than at lower concentrations. In the LMIT, G. glabra showed concentration-dependent efficacy (R2 = 0.971), while considerably reduced efficacy was observed for glycyrrhetinic acid (R2 = 0.855) at the lowest concentrations. These data suggest that the two compounds may have different mechanisms of action. In the LMIT, the 50% lethal concentration (LC50) of glycyrrhetinic acid (~5.12 mg/mL) was > 2.0-fold lower when compared to G. glabra (12.25 mg/mL). Analysis and previous findings indicated low toxicity for both compounds. The results obtained encourage in vivo studies aimed at evaluating the potential use of the tested compounds as natural de-wormers in ruminants.
Homotopic approach for turnpike and singularly perturbed optimal control problems
Authors: Cots Olivier , Gergaud Joseph , Wembe Boris
Published: September 2021

The first aim of this article is to present the link between the turnpike property and the singular perturbations theory: the first one being a particular case of the second one. Then, thanks to this link, we set up a new framework based on continuation methods for the resolution of singularly perturbed optimal control problems. We consider first the turnpike case, then, we generalize the approach to general control problems with singular perturbations (that is with fast but also slow variables). We illustrate each step with an example.
Bonding und Self-Attachment zur Unterstützung des Stillbeginns
Authors: Lamprecht Beate Elvira , Zittera Ingrid
Published: September 2021

Bindungsförderung durch Gestaltung der frühen sensitiven Periode in den ersten Stunden nach der Geburt ist eine Kernaufgabe der Hebamme. Dies gilt auch für die Begleitung des Beginns einer Stillbeziehung. Aktuelle Best-practice-Empfehlungen und Leitlinien sollten umgesetzt werden – sei es als Hausgeburtshebamme, im interdisziplinären Team oder als Lehrende. Grundlage dafür ist primär die Bereitschaft, eigene Routinen immer wieder vor dem Hintergrund aktueller Evidenz zu reflektieren und aufgeschlossen neue Wege zu beschreiten.
Relaktation: Möglichkeiten und Grenzen
Authors: Glaß Alexandra
Published: September 2021

Möchte eine abgestillte Mutter das Stillen wieder beginnen, ist das grundsätzlich möglich. Durch Relaktation kann die Milchbildung erneut angeregt werden und der Säugling das Trinken an der Brust erlernen. Hebammen können stillenden Frauen mit Informationen, Rat und Hilfsmitteln durch diesen Prozess begleiten.
Group-Assisted-Purification Chemistry Strategy for the Efficient Assembly of Cyclic Fused Pyridinones
Authors: Chen Wenteng , Ke Di , Wu You , Zhang Lei , Shao Jiaan , Yu Yongping
Published: September 2021

A group-assisted-purification (GAP) chemistry strategy-based Ugi four-center three-component reaction (Ugi-4C-3CR) was explored. The reaction proceeded well to deliver the cyclic fused pyridinones selectively. Moreover, the reaction conditions were mild and avoided additional chromatography or recrystallization workup. Also, wide variations in substrates, such as anilines and aliphatic amines as well as amino alcohols and amino acid esters were all tolerated and pyridinones are achieved in good to excellent yields. Importantly, ladder-type cyclic fused pyridinones can be further constructed in excellent yield of 91%.
Dihydroxylation Studies of Isoquinolinones: Synthesis of the EF-Ring of Lysolipin I
Authors: Menche Dirk , Heinemann Maximilian J. B. , Voigt Thomas
Published: September 2021

Inspired by the potent polycyclic xanthone antibiotic lysolipin I, a general study on asymmetric dihydroxylation reactions of variously substituted isoquinolinones was performed. Different isoquinolinones were efficiently prepared, either by a Pomeranz–Fritsch type condensation or a Curtius rearrangement. Under a broad variety of conventional oxygenation procedures, they proved very unreactive. However, either by suitable substitution of the appending aromatic ring or more forcing conditions a dihydroxylation could finally be performed, which allowed the synthesis of the EF-ring of lysolipin I.
Evidence for Reversal of Immunosuppression by Homeopathic Medicine to a Predominant Th1-type Immune Response in BALB/c Mice Infected with Leishmania donovani
Authors: Joshi Jyoti , Bandral Chetna , Manchanda Raj Kumar , Khurana Anil , Nayak Debadatta , Kaur Sukhbir
Published: August 2021

Background Visceral leishmaniasis (VL) is a neglected tropical disease that is fatal if treatment is not given. The available chemotherapeutic options are unsatisfactory, and so complementary therapies like homeopathy might be a promising approach.

Methods A nosode from a pure axenic culture of Leishmania donovani was prepared and screened for its anti-leishmanial potential both in an in-vitro and an in-vivo experimental approach.

Results Leishmania donovani amastigote promastigote nosode (LdAPN 30C) exhibited significant anti-leishmanial activity against the promastigote forms of Leishmania donovani and was found to be safe. A study conducted on VL-infected mice revealed that LdAPN 30C resolved the disease by modulating the host immune response toward the Th1 type through upregulating the pro-inflammatory cytokines (IFN-γ and IL-17) and inducing nitric oxide (NO) levels in the infected macrophages. The hepatic parasite load was also found to be significantly decreased. The nosode was found to be safe, as no histological alterations in the liver or kidney were observed in the animals treated with the LdAPN 30C.

Conclusion This is the first study in which an axenic culture of Leishmania donovani has been used for the preparation of a homeopathic medication. The study highlights the anti-leishmanial and immunomodulatory potential of a homeopathic nosode in experimental VL.
Hypergraph min-cuts from quantum entropies
Authors: Walter Michael , Witteveen Freek
Published: September 2021

The von Neumann entropy of pure quantum states and the min-cut function of weighted hypergraphs are both symmetric submodular functions. In this article, we explain this coincidence by proving that the min-cut function of any weighted hypergraph can be approximated (up to an overall rescaling) by the entropies of quantum states known as stabilizer states. We do so by constructing a novel ensemble of random quantum states, built from tensor networks, whose entanglement structure is determined by a given hypergraph. This implies that the min-cuts of hypergraphs are constrained by quantum entropy inequalities, and it follows that the recently defined hypergraph cones are contained in the quantum stabilizer entropy cones, which confirms a conjecture made in the recent literature.
Experimental diagnosis of electron density and temperature in capacitively coupled argon plasmas: Triple-frequency discharges and two-dimensional spatial distributions
Authors: Wu Jidun , Zheng Hao , Wang Yanfei , Cao Qilu , Zhou Fengzhu , Zhang Jiaojiao , Huang Xiaojiang
Published: September 2021

An approach combining optical emission spectroscopy with a collisional radiative model (OES-CRM) has been used to diagnose electron density and electron temperature in low pressure capacitively coupled argon plasmas. The electron density and electron temperature obtained by the OES-CRM show reasonable agreement with the results measured by a Langmuir probe. The method was first applied to diagnosis in triple-frequency (2, 13.56, and 27.12 MHz) plasmas. Compared with dual-frequency (2 and 27.12 MHz) discharges, it was found that in triple-frequency discharges, the high frequency source controls electron density more independently and with less influence on electron temperature as the intermediate frequency power increases. Next, the method was extended to a two-dimensional diagnosis based on the use of a charge coupled device camera and optical bandpass interference filters. The results showed that the axial and radial distributions of the electron density are more uniform at a lower radio frequency (RF) power. The axial uniformity of the electron density is better at a lower discharge frequency while the radial profiles of the electron temperature are flatter at a higher frequency. In all the cases, the electron temperature is highly uniform within the bulk plasma. Moreover, a mode transition from an α to a γ mode is observed at 13.56 MHz with the increasing RF power, and this is accompanied by a significant enhancement in electron density and a sharp reduction in electron temperature.
State-of-art affordable bioprinters: A guide for the DiY community
Authors: Garciamendez-Mijares Carlos Ezio , Agrawal Prajwal , García Martínez Germán , Cervantes Juarez Ernesto , Zhang Yu Shrike
Published: September 2021

The use of bioprinting as a powerful tool for tissue and organ fabrication has been a promising development in the field of biomedicine, offering unprecedented versatility in the fabrication of biologically and physiologically relevant constructs. Even though there are a plethora of commercial bioprinters available in the market, most of them are overly expensive. Thus, university facilities and independent research groups often find it difficult, if not impossible, to equip themselves with such machinery. In this Review, we analyze affordable alternatives to commercial bioprinters, which are presented by the Do-it-Yourself (DiY) community. First, we discuss the current state of these low-cost technologies, and the advances made to bridge the divergence between marketed bioprinters and DiY devices. Afterwards, the different bioprinting technologies that are most commonplace for these low-cost devices are examined. Additionally, an overview of the pioneering DiY bioprinters takes place, as well as the open-source software alternatives to control these bioprinters. Next, we analyze the different factors to take into consideration during the bioprinting workflow, such as bioinks, computer-aided models, and bioprinting parameters. Finally, we conclude with a brief assessment of current limitations and potential solutions, as well as future developments in the arena of bioprinting.
Free space Thomson scattering to study high energy density shocks
Authors: Banasek J. T. , Oliver T. G. , Cordaro S. W. , Bott-Suzuki S. C.
Published: September 2021

A free space collective Thomson scattering system has been developed to study pulsed power produced plasmas. While most Thomson scattering diagnostics on pulsed power machines use a bundle of fibers to couple scattered light from the plasma to the spectrometer, this system used free space coupling of the light, which enabled a spatially continuous image of the plasma. Initial experiments with this diagnostic were performed on an inverse wire array generated by a 200 kA, 1100 ns rise time pulse power generator. The capabilities of this diagnostic were demonstrated by using the low frequency ion acoustic wave feature of the Thomson scattering spectra to measure the plasma flow velocity. The diagnostic was demonstrated to measure velocities between 20 and 40 km/s with an error of 4.7 km/s when fitting with a 600 μm spatial resolution or 8.9 km/s when fitting with a 150 μm spatial resolution. In some experiments, the diagnostic observed a bow shock in the plasma flow as the scattering intensity increased and flow velocity decreased.
Global existence and singularity of Hill’s lunar problem with strong potential
Authors: Deng Yanxia , Ibrahim Slim
Published: September 2021

We characterize the fate of solutions of Hill’s lunar problem using ideas of ground states from partial differential equations. In particular, we define the equilibrium of Hill’s lunar problem as the ground state and show that it satisfies some crucial energetic variational properties. We then classify the dynamics of solutions below, at, and (slightly) above the ground state energy threshold.
Decomposable Pauli diagonal maps and tensor squares of qubit maps
Authors: Müller-Hermes Alexander
Published: September 2021

It is a well-known result due to Størmer [Acta Math. 110, 233–278 (1963)] that every positive qubit map is decomposable into a sum of a completely positive map and a completely copositive map. Here, we generalize this result to tensor squares of qubit maps. Specifically, we show that any positive tensor product of a qubit map with itself is decomposable. This solves a recent conjecture by Filippov and Magadov [J. Phys. A: Math. Theor. 50(5), 055301 (2017)]. We contrast this result with examples of non-decomposable positive maps arising as the tensor product of two distinct qubit maps or as the tensor square of a decomposable map from a qubit to a ququart. To show our main result, we reduce the problem to Pauli diagonal maps. We then characterize the cone of decomposable ququart Pauli diagonal maps by determining all 252 extremal rays of ququart Pauli diagonal maps that are both completely positive and completely copositive. These extremal rays split into three disjoint orbits under a natural symmetry group, and two of these orbits contain only entanglement breaking maps. Finally, we develop a general combinatorial method to determine the extremal rays of Pauli diagonal maps that are both completely positive and completely copositive between multi-qubit systems using the ordered spectra of their Choi matrices. Classifying these extremal rays beyond ququarts is left as an open problem.
Terahertz imaging with self-pulsations in quantum cascade lasers under optical feedback
Authors: Qi Xiaoqiong , Bertling Karl , Taimre Thomas , Lim Yah Leng , Gillespie Tim , Dean Paul , Li Lian He , Linfield Edmund H. , Davies A. Giles , Indjin Dragan , Rakić Aleksandar D.
Published: September 2021

The phenomenon of self-pulsation (SP) in terahertz (THz) quantum cascade lasers (QCLs) due to optical feedback was reported recently. In this Letter, we propose a THz imaging modality using the SP phenomenon in a THz QCL. We explore the theoretical oscillation properties of the SP scheme and demonstrate its suitability to perform imaging experimentally. The SP imaging scheme operates in self-detection mode, eliminating the need for an external detector. Moreover, the scheme requires only a fixed current, meaning that one can avoid many of the pitfalls associated with high temperature operation of THz QCLs, including frequency chirp and mode hops caused by sweeping the laser current. This also means that one is free to locate the operating point at the maximum power, to produce the desired beam profile or for highest spectral purity, depending on the application. The SP imaging modality proposed in this work can be translated directly to high operating temperature THz QCLs.
Deep-learning-enabled Bayesian inference of fuel magnetization in magnetized liner inertial fusion
Authors: Lewis William E. , Knapp Patrick F. , Slutz Stephen A. , Schmit Paul F. , Chandler Gordon A. , Gomez Matthew R. , Harvey-Thompson Adam J. , Mangan Michael A. , Ampleford David J. , Beckwith Kristian
Published: September 2021

Fuel magnetization in magneto-inertial fusion (MIF) experiments improves charged burn product confinement, reducing requirements on fuel areal density and pressure to achieve self-heating. By elongating the path length of 1.01 MeV tritons produced in a pure deuterium fusion plasma, magnetization enhances the probability for deuterium–tritium reactions producing 11.8−17.1 MeV neutrons. Nuclear diagnostics thus enable a sensitive probe of magnetization. Characterization of magnetization, including uncertainty quantification, is crucial for understanding the physics governing target performance in MIF platforms, such as magnetized liner inertial fusion (MagLIF) experiments conducted at Sandia National Laboratories, Z-facility. We demonstrate a deep-learned surrogate of a physics-based model of nuclear measurements. A single model evaluation is reduced from O(10–100) CPU hours on a high-performance computing cluster down to O(10) ms on a laptop. This enables a Bayesian inference of magnetization, rigorously accounting for uncertainties from surrogate modeling and noisy nuclear measurements. The approach is validated by testing on synthetic data and comparing with a previous study. We analyze a series of MagLIF experiments systematically varying preheat, resulting in the first ever systematic experimental study of magnetic confinement properties of the fuel plasma as a function of fundamental inputs on any neutron-producing MIF platform. We demonstrate that magnetization decreases from BR∼0.5 to BR∼0.2 MG cm as laser preheat energy deposited increases from Epreheat∼460 J to Epreheat∼1.4 kJ. This trend is consistent with 2D LASNEX simulations showing Nernst advection of the magnetic field out of the hot fuel and diffusion into the target liner.
Evidence for trapping-induced nonlinear frequency shifts in Langmuir waves driven via stimulated Raman scattering
Authors: Finnegan S. M. , Kline J. L. , Montgomery D. S. , Yin L. , Schmitt M. J. , Johnson R. P. , Albright B. J. , Rose H. A.
Published: September 2021

Thomson scattering is used to detect the spectra of Langmuir waves driven through the backward stimulated Raman scattering process in a diffraction limited laser focal spot. Measured Langmuir wave spectral frequencies are found to vary in time and have broadened spectral power, consistent with a nonlinear frequency shift of the driven Langmuir wave due to electron-trapping. Broadening of the Langmuir wave spectral power is observed to decrease in time, consistent with measured variations in the frequency shift of the driven Langmuir waves. Furthermore, the observed spectral broadening is consistent with the temporally short (ps), bursty nature of backward stimulated Raman scattered light observed in simulations that cannot be resolved by the Thomson scattering diagnostic. Comparison of the broadened spectrum with time integrated spectra from two-dimensional particle-in-cell simulations shows favorable comparison in the broadened spectral widths, supporting the supposition of electron-trapping induced, nonlinear shifting of daughter Langmuir wave frequencies.
Principles of spintronic THz emitters
Authors: Wu Weipeng , Yaw Ameyaw Charles , Doty Matthew F. , Jungfleisch M. Benjamin
Published: September 2021

Significant progress has been made in answering fundamental questions about how and, more importantly, on what time scales interactions between electrons, spins, and phonons occur in solid state materials. These complex interactions are leading to the first real applications of terahertz (THz) spintronics: THz emitters that can compete with traditional THz sources and provide additional functionalities enabled by the spin degree of freedom. This Tutorial article is intended to provide the background necessary to understand, use, and improve THz spintronic emitters. A particular focus is the introduction of the physical effects that underlie the operation of spintronic THz emitters. These effects were, for the most part, first discovered through traditional spin-transport and spintronic studies. We, therefore, begin with a review of the historical background and current theoretical understanding of ultrafast spin physics that has been developed over the past 25 years. We then discuss standard experimental techniques for the characterization of spintronic THz emitters and—more broadly—ultrafast magnetic phenomena. We next present the principles and methods of the synthesis and fabrication of various types of spintronic THz emitters. Finally, we review recent developments in this exciting field including the integration of novel material platforms such as topological insulators as well as antiferromagnets and materials with unconventional spin textures.
Continuum simulation of non-local effects in a granular silo discharge flow using a regularized μ(I) rheology model
Authors: Lin Cheng-Chuan , Yang Fu-Ling
Published: September 2021

The effect of non-local momentum transport on a silo discharge process is numerically investigated using a continuum simulation with the μ(I) rheology model in which the gradient expansion model is adopted to account for the non-local effects due to the non-uniform field of inertial number I [Bouzid et al., Phys. Rev. Lett. 111, 238301 (2013)]. The singularity for I = 0 is handled with a regularization scheme [Lin and Yang, J. Comput. Phys. 420, 109708 (2020)]. Compared to the discharge dynamics predicted with the local μ(I) rheology model, the non-local effect enhances the velocity field to increase the volume discharge flow rate Q, especially when the silo orifice L is narrower. Both the local and non-local flow simulations conform to the Beverloo relation Q=Cρg(L−kd)3/2, where d is the intrinsic grain diameter but the non-local effects appear to lessen the orifice reduction effect coefficient k. The difference between the local and the non-local flow rates ΔQ¯, made dimensionless by ρgd3/2, grew monotonically with decreasing L/d with a slight enhancement if the silo height-to-width aspect ratio deviates from unity. Finally, we evaluated the ratio of the shear strain rate to the instantaneous maximum value to define a high-shear zone when the ratio is above a threshold and studied its evolution from the onset to the end of the discharge process. Interestingly, non-local momentum transport helped to reduce the size of the high-shear zone to give a more uniformly fluidized central zone above the orifice.
Dynamics of wall jet flow under external pulsation
Authors: Mishra Abhishek , Djenidi Lyazid , Agrawal Amit
Published: September 2021

The present study aims to identify the dominant coherent structures in the wall jet flow subjected to external pulsation at Reynolds number 2600 (based on average jet exit velocity and nozzle diameter). The forcing frequency is varied between St = 0 and 0.99 (St is the Strouhal number). Quadrant analysis is employed to identify the relative contribution of different quadrant motions to the total Reynolds shear stress. Unlike boundary layer flows and channel flows, two distinct regions (inner shear region and outer shear region) are observed in the wall jet flows, and the characteristics of different quadrant motions change in these regions. About 70% of the total shear stress is contributed from the first and fourth quadrants in the outer shear region. We observe that ejection motion is more energetic than sweep motion in the downstream direction, although less frequent. The ejection motion is observed to be more violent for St = 0.44 than for the other frequencies. A proper orthogonal decomposition (POD) analysis reveals while the modal structures exist in different regions of the wall for different jet pulsation; there are no dominant modes (30 modes are required to recover about 75% of the total energy), and the energy is fairly distributed over a large number of modes. However, the POD analyses are capable of capturing the response of the wall jet to different jet pulsations. The most dominant and strongest modal structures are found nearer to the impingement region of the wall when St = 0.44 and the jet tends to laminarize for St > 0.9.
High-pulse-energy III-V-on-silicon-nitride mode-locked laser
Authors: Hermans Artur , Van Gasse Kasper , Kjellman Jon Ø. , Caër Charles , Nakamura Tasuku , Inada Yasuhisa , Hisada Kazuya , Hirasawa Taku , Cuyvers Stijn , Kumari Sulakshna , Marinins Aleksandrs , Jansen Roelof , Roelkens Günther , Soussan Philippe , Rottenberg Xavier , Kuyken Bart
Published: September 2021

Mode-locked lasers find their use in a large number of applications, for instance, in spectroscopic sensing, distance measurements, and optical communication. To enable widespread use of mode-locked lasers, their on-chip integration is desired. In recent years, there have been multiple demonstrations of monolithic III-V and heterogeneous III-V-on-silicon mode-locked lasers. However, the pulse energy, noise performance, and stability of these mode-locked lasers are limited by the relatively high linear and nonlinear waveguide loss, and the high temperature sensitivity of said platforms. Here, we demonstrate a heterogeneous III-V-on-silicon-nitride (III-V-on-SiN) electrically pumped mode-locked laser. SiN’s low waveguide loss, negligible two-photon absorption at telecom wavelengths, and small thermo-optic coefficient enable low-noise mode-locked lasers with high pulse energies and excellent temperature stability. Our mode-locked laser emits at a wavelength of 1.6 μm, has a pulse repetition rate of 3 GHz, a high on-chip pulse energy of ≈2 pJ, a narrow RF linewidth of 400 Hz, and an optical linewidth <1 MHz. The SiN photonic circuits are fabricated on 200 mm silicon wafers in a CMOS pilot line and include an amorphous silicon waveguide layer for efficient coupling from the SiN to the III-V waveguide. The III-V integration is done by micro-transfer-printing, a technique that enables the transfer of thin-film devices in a massively parallel manner on a wafer scale.
Synchronization transitions in a hyperchaotic SQUID trimer
Authors: Shena J. , Lazarides N. , Hizanidis J.
Published: September 2021

The phenomena of intermittent and complete synchronization between two out of three identical, magnetically coupled Superconducting QUantum Interference Devices (SQUIDs) are investigated numerically. SQUIDs are highly nonlinear superconducting oscillators/devices that exhibit strong resonant and tunable response to applied magnetic field(s). Single SQUIDs and SQUID arrays are technologically important solid-state devices, and they also serve as a testbed for exploring numerous complex dynamical phenomena. In SQUID oligomers, the dynamic complexity increases considerably with the number of SQUIDs. The SQUID trimer, considered here in a linear geometrical configuration using a realistic model with experimentally accessible control parameters, exhibits chaotic and hyperchaotic behavior in wide parameter regions. Complete chaos synchronization as well as intermittent chaos synchronization between two SQUIDs of the trimer is identified and characterized using the complete Lyapunov spectrum of the system and appropriate measures. The passage from complete to intermittent synchronization seems to be related to chaos–hyperchaos transitions as has been conjectured in the early days of chaos synchronization.
Point-to-point trajectory planning for space robots based on jerk constraints
Authors: Xiao Pengfei , Ju Hehua , Li Qidong
Published: September 2021

This paper studies the Cartesian point-to-point optimal trajectory planning for space robots oriented to space maintenance operations. Aiming at the problems of poor stability, large base disturbance, and large joint variation in the motion planning of point-to-point maintenance in space, a planning method is proposed to minimize the base disturbance and the total joint angle variation under the jerk constraint on the premise of ensuring the accuracy of the end pose. First, the attitude of the space robot is described by the unit quaternion, and the velocity relationship between the joint angle, the end effector, and the base posture is introduced. Then, the joint trajectories were parameterized by a fifth degree polynomial, and a trajectory planning model with the minimum perturbation of the base and the minimum variation of the joint of the manipulator was established under the condition that the end effector satisfied the pose and the jerk constraint. Finally, a multi-objective optimization algorithm is proposed to deal with the trajectory optimization problem under nonlinear constraints. The simulation results show that the proposed trajectory planning method can optimize the base attitude and joint angle of the space manipulator under the premise of the optimal trajectory and stability of the terminal execution tool, which ensures the stability of the space robot’s on-orbit service and reduces the energy consumption.
Investigation of quantum oscillations in ZnO/CdO heterostructure
Authors: da Silva M. J. , Vargas L. M. B. , de Godoy M. P. F. , Bolaños K. , Soares D. A. W. , de Castro S. , Peres M. L.
Published: September 2021

We report on the observation of the Shubnikov–de Haas oscillation in a polycrystalline ZnO/CdO heterostructure grown on a silicon substrate by a spray pyrolysis technique in temperatures below 6 K. From the analysis of these quantum oscillations, we obtained the cyclotronic effective mass, the 2D carrier concentration, and the thickness of the two-dimensional electron gas in the interface of the two layers. The results suggest that a two-dimensional electron gas is successfully obtained at the ZnO/CdO interface.
Instability of mixed convection flow in a differentially heated channel under a transverse magnetic field with internal heating
Authors: Singh Nidhi , Khandelwal Manish K. , Yu Peng
Published: September 2021

This paper reports the linear stability of laminar magnetohydrodynamic (MHD) mixed convection flow in a differentially heated channel under a transverse magnetic field with the internal heating. Three different electrically conducting fluids, such as liquid mercury, water-based electrolytes, and Flibe (a molten salt mixture of lithium fluoride and beryllium fluoride), are considered to examine the present study. A spectral collocation method is used to solve the governing equations. The impact of the magnetic field and strength of the internal heating on the instability mechanism is examined. The results show that the MHD fully developed flow stabilizes on increasing the strength of the magnetic field, whereas it destabilizes on increasing the strength of the heat source parameter. The stability of flow also decreases by increasing the Reynolds number. The flow of liquid mercury is more stable in comparison with water-based electrolytes and the Flibe case. The kinetic energy balance shows that the high strength of the magnetic field leads to a significant reduction of the energy amplification of the disturbances. In contrast, the strength of the internal heating acts in a reverse way. Three different types: shear, thermal-shear, and thermal-buoyant, instabilities are observed as a function of Hartmann number for liquid mercury. The type of instability for water-based electrolytes and Flibe is only thermal buoyant. The disturbance flow moves toward the cold wall of the channel on increasing the strength of the magnetic field for all considered fluids, whereas it shifts to the entire channel on increasing the strength of the heat source parameter.
Investigation of the toroidal flow damping in the edge plasma of J-TEXT tokamak with an electrode biasing
Authors: Liu Hai , Zhang Bo , Xu Yuhong , Chen Zhipeng , Cheng Jun , Liu Haifeng , Wang Xianqu , Huang Jie , Zhang Xin , Tang Changjian , Shao Junren ,   J-TEXT Team
Published: September 2021

The toroidal flow damping has been investigated in the edge plasma of J-TEXT tokamaks with an electrode biasing (EB). The estimated viscosity of the toroidal flow after the bias turning off is about 67 times of the classical viscosity and four times of the neo-classical viscosity, which infers that the flow damping is anomalous in the transition phase. In the equilibrium phase, the torque densities driven by the EB, the momentum transport, and the neo-classical toroidal viscosity (NTV) under different bias conditions are calculated, which show that the NTV torques are comparable with the other terms. According to the angular momentum balance equation, the remnant damping torque densities and the effective damping coefficients have been obtained. Considering that the remnant damping is mainly contributed by the neutral particle damping, this investigation provides a method to estimate the neutral particle density (nH), which gives that the nH in the edge plasma of J-TEXT is in the range of 1–4 (×1017 m−3).
Ge doping of β-Ga2O3 by MOCVD
Authors: Alema Fikadu , Seryogin George , Osinsky Alexei , Osinsky Andrei
Published: September 2021

We report on the Ge doping of Ga2O3 using metalorganic chemical vapor deposition (MOCVD) epitaxy. The effects of the GeH4/N2 flow rate, substrate temperature, VI/III ratio, type of Ga precursor, and MOCVD reactor geometry on the incorporation efficiency of Ge into Ga2O3 were explored. The Ge concentration incorporated into the films was quantified using Hall and secondary ion mass spectroscopy measurements. The increase in the GeH4/N2 flow rate, decrease in the substrate temperature, and increase in the VI/III ratio increase the amount of Ge incorporated into Ga2O3. The incorporation of Ge into the lattice of Ga2O3 was found to be strongly dependent on the substrate temperature, i.e., lowering the growth temperature leads to a higher doping concentration. Films with a free carrier concentration ranging from ∼2 × 1016 to ∼3 × 1020 cm−3 and corresponding mobilities ranging from ∼140 to ∼38 cm2/Vs were realized. The incorporation of Ge into the films was also found to be strongly dependent on the metalorganic precursor type used for the growth of the Ga2O3 film. We found that it was more challenging to dope Ga2O3 with Ge using trimethylgallium rather than triethylgallium as a source for Ga. Additionally, we found that Ge doping has a strong memory effect dependent on the reactor geometry. The result highlights the challenges in achieving controllable Ge doping for n-type conductivity despite all the positive indicators from theoretical studies that suggest that Ge is a suitable dopant candidate for Ga2O3 similar to Si and Sn.
Ion beam etching dependence of spin–orbit torque memory devices with switching current densities reduced by Hf interlayers
Authors: Ren Haowen , Wu Shih-Yu , Sun Jonathan Z. , Fullerton Eric E.
Published: September 2021

We report on the fabrication of nanoscale, three-terminal in-plane spin–orbit torque switching devices with low switching current densities. Critical parameters in the fabrication process, including the ion beam etching angle and time, were optimized to avoid fabrication defects and improve device yield. Measurements of the magnetic field and current-induced switching behavior of the tunnel junctions demonstrate a sensitivity to the nanopillar aspect ratio, which dictates the nanopillars’ anisotropy and thermal stability. Additionally, we show that the current density required for switching can be reduced and the device thermal stability increased by inserting Hf interlayers into the heterostructure. Micromagnetic simulations are generally consistent with the experimentally observed switching behavior, suggesting an increase in the interfacial perpendicular anisotropy at the CoFeB/MgO interface and the reduction in the Dzyaloshinskii–Moriya interaction at the W/CoFeB interface by the Hf interlayers.