bluuebunny/crossref_metadata_2025 huggingface dataset:
Darstellung von retinalen Neovaskularisationen mit der optischen Kohärenztomografie-Angiografie im Vergleich mit der Fluoreszeinangiografie
Authors: Enders Christian , Baeurle Franziska , Lang Gabriele E. , Dreyhaupt Jens , Trick Simon , Kilani Adnan , Lang Gerhard K. , Werner Jens Ulrich
Published: November 2019

Zielsetzung Vergleichende Darstellung von retinalen papillären (NVD) und nicht papillären (NVE) Neovaskularisationen in der optischen Kohärenztomografie-Angiografie (OCTA) und in der Fluoreszeinangigrafie (FA) bei Patienten mit proliferativer diabetischer Retinopathie.

Material und Methoden 15 konsekutive Patienten wurden in diese Studie aufgenommen. Alle Patienten erhielten eine OCTA, wobei jeweils ein Scan von 3 × 3 mm der „Region of Interest“ mit dem ZEISS OCT Cirrus 5000 mit dem AngioPlex-Modul aufgenommen wurde. Die Größe der Neovaskularisation (NV) wurde manuell in OCTA und FA ermittelt und zwischen den beiden Messmethoden verglichen.

Ergebnisse 20 Augen von 15 Patienten mit proliferativer diabetischer Retinopathie (PDR) mit einem Durchschnittsalter von 57 Jahren wurden eingeschlossen. Die mittlere Größe der NVDs betrug in der OCTA 3,44 mm2 und in der FA 3,75 mm2, die mittlere Größe der NVDs betrug in der OCTA 1,06 mm2 und in der FA 1,54 mm2. Unter Berücksichtigung einer in der FA generell größer gemessenen Fläche zeigte sich insgesamt eine gute Übereinstimmung der beiden Methoden.

Schlussfolgerung Es zeigte sich eine gute Übereinstimmung für die Größe der NVs in beiden Untersuchungsmethoden. Die OCTA kann als einfache und nicht invasive Methode zur Darstellung von retinalen Neovaskularisationen die gängige Diagnostik bestätigen.
Utility of autologous fibrin glue and polyglycolic acid sheet for preventing delayed bleeding associated with antithrombotic therapy after gastric ESD
Authors: Kikuchi Daisuke , Iizuka Toshiro , Makino Shigeyoshi , Hayasaka Junnosuke , Odagiri Hiroyuki , Ochiai Yorinari , Suzuki Yugo , Nomura Kosuke , Ohkura Yu , Okamoto Yosuke , Tanaka Masami , Matsui Akira , Mitani Toshifumi , Hoteya Shu
Published: November 2019

Background and study aims Delayed bleeding is one of the most serious adverse events of gastric endoscopic submucosal dissection (ESD), especially in patients taking antithrombotic therapy. This study aimed to evaluate the utility and safety of a shielding method with autologous fibrin glue and polyglycolic acid (PGA) sheets for patients undergoing gastric ESD who are receiving antithrombotic therapy.

Patients and methods One hundred twenty-three patients who were treated with gastric ESD while receiving antithrombotic therapy between December 2014 and September 2017 were enrolled in this study. Patients who received the shielding method were classified into the shielding group. Others were classified into the conventional group. Various clinico-pathological factors were retrospectively compared between the two groups.

Results The shielding group consisted of 38 patients, and the conventional group consisted of the remaining 85 patients. In the shielding group, the rate of continuation of antithrombotic therapy was significantly higher (68.4 % vs 41.2 %). Incidence of delayed bleeding was lower in the shielding group (2.6 %, 1/38) than in the conventional group (14.1 %, 12/85). In the propensity score-adjusted logistic regression analysis, the delayed bleeding rate in the shielding group tended to be lower than in the conventional group (P = 0.070). Allogeneic transfusion was performed in eight patients (8/85, 9.4 %) in the conventional group and none in the shielding group (P = 0.047). No adverse event associated with endoscopic shielding were observed in the shielding group.

Conclusions This study suggests that a shielding method with autologous fibrin glue and PGA sheet effectively prevents delayed bleeding after gastric ESD in patients receiving antithrombotic therapy.
The FUSION iENA Study: Comparison of I-124-PET/US Fusion Imaging with Conventional Diagnostics for the Functional Assessment of Thyroid Nodules by Multiple Observers
Authors: Winkens Thomas , Seifert Philipp , Hollenbach Christian , Kühnel Christian , Gühne Falk , Freesmeyer Martin
Published: November 2019

Aim To investigate the value of I-124 positron emission tomography (PET) / ultrasound (US) fusion imaging in comparison to conventional diagnostics (CD) of Thyroid nodules (TN) by multiple observers.

Methods Digital patient case files (PCF) of patients that received CD and I-124-PET/US in clinical routine were prepared containing cine-loops of the examinations. All physicians with nuclear medicine specialty from Germany, Austria, and Switzerland were invited to participate. 106 acquired observers completed 7.2 ± 1.8 (median: 8, range: 4–14) randomly assigned PCF (CD only or CD+PET/US). They assessed the TN function, stated their confidence in functional assessment, and suggested a treatment course for each TN.

Results 68 PCF of 34 patients comprising 66 TN ≥ 1 cm (= 1.94 TN/patient) were created. A total of 748 (11.2/TN), and 751 ratings (11.4/TN) were recorded for CD only, and CD+PET/US, respectively. The functional assessment revealed more hyper- or hypofunctioning (524 vs. 320, p < 0.0001) and less indifferent or not rateable (209 vs. 428, p < 0.0001) TN in CD+PET/US vs. CD only. The observers’ confidence in functional assessment was superior in CD+PET/US (p < 0.0001). Furthermore, the ratings were carried out more homogeneous in CD+PET/US (p < 0.0001). Fewer suggestion of follow up (p < 0.0001), and more (p < 0.0001) suggestion of invasive treatments (fine-needle aspiration & surgery) was observed in CD+PET/US. Radioiodine therapy was more often (p = 0.0036), and thyroid medication less often (p = 0.0167) advised in CD+PET/US.

Conclusion Functional assessment of equivocal TN shows frequent failures in CD, underestimating the incidence of hyper- and hypofunctioning lesions. Confidence in functional assessment significantly increases with additional PET/US. This influences the proposed treatment course.
Formal [8+3]-Annulation between Azaoxyallyl Cations and Tropones
Authors: Force Guillaume , Pérot Amélie , Guillot Régis , Gandon Vincent , Leboeuf David
Published: November 2019

For the first time, azaoxyallyl cations were used as cycloaddition partners with tropone derivatives to access nitrogen-containing [7,6]-fused bicycles in a metal-free process under mild reaction conditions. DFT computations have been used to shed light on the selectivities observed during the course of the reaction.
Organosilicon-Mediated Organic Synthesis (SiMOS): A Personal Account
Authors: Li Li , Wei Yun-Long , Xu Li-Wen
Published: November 2019

The organosilicon-mediated organic synthesis (SiMOS) has attracted much attention over the recent decades. However, the use of organosilicon reagents with novel catalytic strategies remains to be explored. This Account summarizes our group’s progress mainly based on the application of a wide variety of organosilicon reagents, including allylic silanes, trifluoromethyl silane, acylsilanes, chlorosilanes, hydrosilanes, trimethylsilyldiazomethane, trimethylsiloxyfuran, silanols, α-trimethylsilylmethylacetate, and trimethylsilylcyanide, in catalysis and organic reactions. These transformations were proved to be alternative procedures for the construction of structurally diverse compounds.

1 Introduction

2 The Exploration of New Reactivity of Organosilicon Reagent in Organic Synthesis

2.1 Allylic Silanes

2.2 Trifluomethylsilane (TMSCF3)

2.3 Acylsilanes

2.4 Chlorosilanes and Hydrosilanes

2.5 Trimethylsilyldiazomethane (TMSD)

2.6 Trimethylsiloxyfuran

2.7 Silanols

2.8 Trimethylsilylcyanide (TMSCN)

3 Conclusion and Perspective
Current Nonoperative Therapeutic Interventions for Lower Gastrointestinal Hemorrhage
Authors: Serur Anna , Rhee Rebecca , Ramjist Joshua
Published: November 2019

Lower gastrointestinal hemorrhage remains a common cause of hospitalization, with significant health care costs. Initial management should include aggressive resuscitation followed by localization of bleeding with nuclear scintigraphy, colonoscopy, or computed tomography (CT) angiography. If bleeding does not resolve spontaneously, expeditious intervention with minimally invasive endoscopic or angiographic methods is necessary with surgical intervention as a last resort.
Epidemiology of Liver Cancer in Latin America: Current and Future Trends
Authors: Carrilho Flair Jose , Paranaguá-Vezozzo Denise Cerqueira , Chagas Aline Lopes , Alencar Regiane Saraiva de Souza Melo , da Fonseca Leonardo Gomes
Published: November 2019

Over 38,000 cases of hepatocellular carcinoma (HCC) are estimated to occur in Latin America annually. The region is characterized by sociocultural heterogeneity and economic disparities, which impose barriers in addressing this major health issue. A significant proportion of patients are still diagnosed in the later stages of the disease, although efforts to implement effective screening programs have been reported by referral centers. While viral hepatitis remains the predominant etiology of liver disease among HCC cases in Latin America, a high prevalence of fatty liver disease in the region is a matter of concern, reflecting the current scenario in many Western countries. In addition, other risk factors such as alcohol, aflatoxin, and early-onset HCC in hepatitis B virus infection contribute to the burden of HCC in Latin America. Interventions to increase screening coverage, expand healthcare access, and implement continuing medical training are key challenges to be overcome.
NUB im Krankenhaus: Konsequenzen fehlender Evidenz?
Authors: Rybak Christian
Published: November 2019

Die Abrechnung von neuen Untersuchungs- und Behandlungsmethoden zu Lasten der gesetzlichen Krankenversicherung ist seit jeher Ausgangspunkt verschiedener rechtlicher Auseinandersetzungen.
Digitale Gesundheit: „Wir werden Krankheiten verhindern“
Authors: Ehrhardt-Joswig Jana
Published: November 2019

Erwin Böttinger ist ein Pionier der personalisierten Medizin und digitalen Transformation des Gesundheitssystems.
Künstliche Intelligenz: Digitale Doppelgänger
Authors: König Romy
Published: November 2019

Sie gelten als nächste Meilensteine der Digitalisierung der Medizin: digitale Zwillinge, die Organe von Menschen individuell und virtuell abbilden können. Mehrere Hersteller arbeiten bereits an mathematischen Modellen dafür.
Sprachgestützte Such-Technologien: „Alexa, was sind die Symptome von Windpocken?“
Authors: Rößing Sabine
Published: November 2019

Die geplante Zusammenarbeit des britischen National Health Service (NHS) mit Amazon erhält nicht nur positive Resonanz, sondern ruft auch Datenschützer auf den Plan.
Altersgerechtes Klinikum: Sensormatten und Farbkontraste: Uniklinikum Würzburg stellt sich auf das Alter ein
Authors: Rößing Sabine
Published: November 2019

Mit umfangreichen baulichen und organisatorischen Veränderungen stellt sich das Uniklinikum Würzburg auf die Herausforderungen durch eine steigende Zahl alter und zunehmend auch dementer Patienten ein. Schrittweise soll sich das Klinikum der medizinischen Fakultät der Julius-Maximilians-Universität zu einem altersgerechten Krankenhaus weiterentwickeln.
Robotik IM OP: Vom talentierten Chirurgen zum Systemmanager
Authors: Kucera Martin
Published: November 2019

Mit der Einführung des Da-Vinci-Systems hat die Robotik im Operationssaal Einzug gehalten. Mittlerweile erschließen auch andere Anbieter diesen Markt. Christoph Hachmöller, Robotik-Experte und Professor für Marketing und Entrepreneurship in der Medizintechnik, erläutert im Gespräch mit kma, wohin die Reise geht und welche Veränderungen damit auf das OP-Personal zukommen.
Digitale-Versorgung-Gesetz: Die Aufholjagd beginnt
Authors: Kohrs Jens
Published: November 2019

In Sachen Digitalisierung ist Deutschland international abgeschlagen. Gesundheitsminister Jens Spahn will das ändern – unter anderem mit dem Digitale-Versorgung-Gesetz. Es soll Innovationen den schnellen Weg in die Regelversorgung ebnen. Doch noch sind viele Fragen offen.
Digitale Patientenaufnahme: Weg vom Papier
Authors: Lang Michael
Published: November 2019

Die Digitalisierung im Krankenhaus hat die zentrale Aufnahme erreicht. Die Krankenhäuser setzen dabei auf die unterschiedlichsten Lösungen, um den Aufwand und die Wartezeiten zu reduzieren.
Multiparametric diagnostic in the synthesis of carbon nanostructures via submerged arc discharge: Stability, nucleation and yield
Authors: Hernandez-Tabares L. , Fortune-Fabregas S. , Chao-Mujica F. J. , Darias-Gonzalez J. G. , Torres-Figueredo N. , Reguera E. , Desdin-Garcia L. F.
Published: November 2019

Submerged arc discharge (SAD) is a simple method to produce carbon nanostructures (CNSs). However, its potential cannot be fully exploited because it generates contaminants and unwanted by-products (CUBPs) that are difficult to eliminate. The formation mechanisms of CNSs and CUBPs were investigated by measuring the correlations between the SAD main parameters (current, voltage, power, anode displacement, and sound emission). It was demonstrated that the SAD takes place in a succession of stable and unstable zones that induce homogeneous and heterogeneous nucleation processes, respectively. In the stable zones, carbon vapor jets are generated and induce the appearance of vortices. Both processes stimulate nucleation. From the measurement of the sound emitted by the jets, the dimensions of the discharge channel were determined. These dimensions match the anode crater size measured by scanning electron microscopy. In the unstable zones, vibrations and thermal stress in the anode intensify. Graphite microparticles are released and act as nucleation centers that induce the formation of CUBPs. While most of the discharge elapses in stable zones, the highest fraction of anode erosion occurs in unstable zones. These results made evident that current theoretical models fail to explain the presence of observed impurities because they do not take into account the influence of vibrations and heterogeneous nucleation. The operation of the synthesis device was simulated, and the results obtained reinforce the aforementioned conclusions. The acoustic emission of the SAD allowed obtaining information on the installation operation for the optimization of its design. Based on this information, recommendations were made for the installation design.
Evolutionary equations and constraints: Maxwell equations
Authors: Ciaglia F. M. , Di Cosmo F. , Marmo G. , Schiavone L.
Published: November 2019

By fixing a reference frame in spacetime, it is possible to split the Euler-Lagrange equations associated with a degenerate Lagrangian into purely evolutionary equations and constraints on the allowed Cauchy data with respect to the notion of space and time associated with the given reference frame. In the context of classical electrodynamics, we introduce a “covariantization procedure” that allows us to invert the perspective and to recover a full-fledged covariant formulation of Maxwell’s equations starting only with constraint equations (i.e., Gauss law and the local version of the law of conservation of magnetic flux) as perceived in a sufficient number of (inertial) reference frames on Minkowski spacetime.
A compact linear-rotary impact motor based on a single piezoelectric tube stator with two independent electrodes
Authors: Han Liling , Yu Liandong , Pan Chengliang , Jiang Yizhou
Published: November 2019

A compact linear-rotary impact motor based on a single piezoelectric tube actuator is proposed. The motor can realize independent linear and rotary motions. With two independent electrodes, the piezoelectric actuator has an outer diameter of 6 mm, a thickness of 0.5 mm, and a length of 25 mm. The actuator produces a maximum axial displacement of 2.17 µm with a driving voltage of 720 Vp-p (peak-to-peak driving voltage), and it produces a maximum torsional angle of 599.98 µrad with a driving voltage of 720 Vp-p. The prototype motor can achieve the independent linear velocities of 6263.45 µm/s and −6331.58 µm/s in the positive and negative directions of motions under the saw-shaped driving voltage of 560 Vp-p at 8 kHz. The motor can realize the independent rotary velocities of 1.22 × 106 µrad/s and −1.21 × 106 µrad/s in the two motions under the saw-shaped driving voltage of 560 Vp-p at 9 kHz. The maximum output force of the motor is 0.45 N, and the maximum output torque is 0.80 mN m for linear and rotary motions, respectively.
Re-examination of effects of sulfur treatment on Al2O3/InGaAs metal-oxide-semiconductor interface properties
Authors: Yoon S.-H. , Kato K. , Yokoyama C. , Ahn D.-H. , Takenaka M. , Takagi S.
Published: November 2019

The effects of wet chemical treatments before treatment using (NH4)2S solutions in atomic layer deposition Al2O3/InGaAs metal-oxide-semiconductor (MOS) interfaces are experimentally examined. It is found that no chemical treatment before sulfur passivation leads to high interface state density (Dit) in spite of the (NH4)2S treatment. Furthermore, the value of Dit is dependent among the pretreatments using NH4OH, HCl, and BHF solutions before the sulfur treatment. HCl + (NH4)2S and BHF + (NH4)2S combinations show the lowest values of Dit. In addition, all of the Al2O3/InGaAs MOS interfaces with the sulfur treatment show a small amount of arsenic oxide. Thus, much higher Dit of the interfaces with the sulfur treatment indicates that the amount of arsenic oxide is not a deterministic factor for Dit. On the other hand, the amount of arsenic oxide before the sulfur treatment is found to correlate with Dit after sulfur treatment. Also, the interfaces with higher Dit after the sulfur treatment show a larger number of sulfur atoms remaining at the interfaces. These experimental results mean that there is a strong correlation among Dit, the amount of arsenic oxide, and the number of sulfur atoms remaining at the Al2O3/InGaAs interfaces. As a result, we can interpret for the present experimental results that the sulfur treatment can have two opposite impacts on Dit at the Al2O3/InGaAs interfaces: the decrease in Dit due to etching of native oxides and suppression of oxidation by sulfur passivation and the increase in Dit due to defect generation through some interaction between sulfur and arsenic oxide.
Design and fabrication of a new multi-loop saddle coil for 1.5 T MRI
Authors: Parsa J. , Mohammadzadeh M.
Published: November 2019

Radiofrequency coils provide high-resolution magnetic resonance (MR) imaging of human tissues. A small RF coil produces MR images with a higher resolution compared to the commercial volume MR coils from mass limited samples. Signal to noise ratio (SNR) plays a key role in the optimal design of receiver radiofrequency coils. In this work, we present a three-loop saddle coil suitable for MR imaging of digits of the human body. The geometry of the introduced coil is optimized to achieve the highest SNR. The coil performance is evaluated through comparing the measured SNR maps of the optimal coil derived from MR images of a saline phantom with the corresponding measured SNR maps of a commercial head coil in axial and sagittal slices. Results verify that the image SNR of the introduced coil is 3.4 times higher than that of the head coil and 2 times higher than that of the similar saddle coils represented in the literature recently. To validate the measured results, SNR maps of the introduced saddle and head coils were simulated and their SNR difference was compared with the corresponding measured data of the two coils. Results show that the simulated and measured data are in agreement with less than 11.8% error.
Electron transport across a magnetic filter: Magnetic field gradient effects on plasma properties
Authors: Oudini N. , Tadjine R. , Alim M. M. , Bendib A.
Published: November 2019

Electron filtering via an external magnetic field barrier is an important issue for volume negative ion production. In this work, we study the plasma properties in an inductively coupled plasma source in the presence of a magnetic filter. Our investigation, conducted through a Langmuir probe, reveals that the magnetic field gradient, i.e., magnetic mirror effect, significantly affects the electron transport. Indeed, our results show that the electron density decreases locally in the tightened magnetic field line region, while the electron temperature is more or less unaffected by the gradient of magnetic field. Moreover, the measurements of plasma potential reveal a nonzero electric field component perpendicular to the magnetic field lines.
Extraordinary quasi-two-dimensional magnetotransport properties of a LaAlO3/SrTiO3 heterostructure tailored with a surface TiO2 atomic sheet
Authors: Ohsawa Takeo , Shimizu Ryota , Iwaya Katsuya , Shiraki Susumu , Nojima Tsutomu , Hitosugi Taro
Published: November 2019

Epitaxial heterostructures of lanthanum aluminate (LaAlO3) and strontium titanate (SrTiO3) exhibit extraordinary quasi-two-dimensional magnetotransport properties at low temperatures. To elucidate the mechanisms responsible for the unique properties of these interfaces, which can guide the design of novel structures having high performances, extensive analyses of the magnetotransport properties at low temperatures are required. We report the magnetotransport properties of a LaAlO3/SrTiO3 system tailored with a topmost surface atomic sheet of titanium dioxide (TiO2). Three unit cells of LaAlO3 were deposited on a reconstructed SrTiO3(001)-(13×13)-R33.7° substrate, yielding LaAlO3 covered with a single-atom-thick TiO2 sheet. The high-mobility electrons confined at the LaAlO3/SrTiO3 interface provided significantly high magnetoresistance ratios of +150% and −80% under magnetic fields perpendicular and parallel to the interface, respectively. The in-plane anisotropic magnetoresistance at 4.2 K reached approximately +30%, reflecting the Rashba spin–orbit interactions of the quasi-two-dimensional electrons. A high carrier concentration at the interface realized by the capping of LaAlO3/SrTiO3 with the surface TiO2 sheet significantly contributed to the enhancement of magnetotransport properties arising from the Ti 3d orbitals.
Polarization mode hybridization and conversion in phononic wire waveguides
Authors: Shen Zhen , Fu Wei , Cheng Risheng , Townley Hendrick , Zou Chang-Ling , Tang Hong X.
Published: November 2019

Phononic wire waveguides of subwavelength cross sections support two orthogonal polarization modes: the out-of-plane motion dominated Rayleigh-like and the in-plane motion dominated Love-like modes, analogous to transverse-electric and transverse-magnetic modes in photonic waveguides. Due to the anisotropic elasticity of the substrate material, the polarization states of phonons propagating along certain crystallographic orientations can strongly hybridize. Here, we experimentally investigate the orientation-dependent mode hybridization in phononic wire waveguides patterned from GaN-on-sapphire thin films. Such mode hybridization allows efficient actuation of piezoelectrically inactive Love-like modes using common interdigital electrodes designed for Rayleigh-like modes and further enables on-chip polarization conversion between guided transverse modes. Both are important for on-chip implementation of complex phononic circuits.
In-depth description of electrohydrodynamic conduction pumping of dielectric liquids: Physical model and regime analysis
Authors: Vázquez P. A. , Talmor M. , Seyed-Yagoobi J. , Traoré P. , Yazdani M.
Published: November 2019

In this work, we discuss the fundamental aspects of Electrohydrodynamic (EHD) conduction pumping of dielectric liquids. We build a mathematical model of conduction pumping that can be applied to all sizes, down to microsized pumps. In order to do this, we discuss the relevance of the Electrical Double Layer (EDL) that appears naturally on nonmetallic substrates. In the process, we identify a new dimensionless parameter related to the value of the zeta potential of the substrate-liquid pair, which quantifies the influence of these EDLs on the performance of the pump. This parameter also describes the transition from EHD conduction pumping to electro-osmosis. We also discuss in detail the two limiting working regimes in EHD conduction pumping: ohmic and saturation. We introduce a new dimensionless parameter, accounting for the electric field enhanced dissociation that, along with the conduction number, allows us to identify in which regime the pump operates.
Pressure densified 1,3,5-tri(1-naphthyl)benzene glass. I. Volume recovery and physical aging
Authors: Holt A. P. , Fragiadakis D. , Roland C. M.
Published: November 2019

The effects of pressure densification on 1,3,5-tri(1-naphthyl)benzene (TNB) are assessed from volumetric and calorimetric measurements. The pressure densified glass (PDG) has higher density than conventional glass (CG), but unlike ultrastable TNB glass prepared using vapor deposition which also has elevated density, TNB PDG exhibits higher enthalpy and lower thermal stability than when formed at ambient pressure. PDG also exhibits anomalous physical aging. Rather than evolving monotonically toward the equilibrium density, there is an overshoot to a lower density state. Only when the density of the PDG becomes equivalent to the corresponding CG does the density begin a slow approach toward equilibrium.
Analyses of bombardment traces on the tube head of a relativistic backward wave oscillator
Authors: Xiao Renzhen , Li Xiaoze , Deng Yuqun , Wu Ping , Shi Yanchao , Yang Dewen , Bai Xianchen , Sun Jun
Published: November 2019

In the repetitive experiments of relativistic backward wave oscillators operating at either low or high magnetic field, we found that the spiral traces appeared on the surfaces of the tube heads (entrance to the reflector and slow wave structure). Three possible causes: electrons emitted from the cathode base, cathode plasma, and cathode negative ion, are analyzed. Among them, the cathode negative ion is the most likely factor leading to the traces. The negative ions are generated by electron impact-ionization and ion impact-ionization of molecules that are desorbed from the cathode by the Ohmic heating of explosive electron emission. Due to the larger mass of negative ion, it cannot be restricted effectively by the magnetic field and will basically move along the electric field line. Many negative ions bombard the tube head with a Larmor radius of several centimeters, and the traces are connected to form spiral lines. The viewpoint of cathode negative ion current is further confirmed by the comparative experiments that show that a graphite cathode after being immersed in water for 12 h results in heavier traces, while a larger anode and cathode gap leads to slighter traces. Some suggestions are provided to reduce the production and the effect of cathode negative ion current.
Single-cell patterning technology for biological applications
Authors: Wang Zihui , Lang Baihe , Qu Yingmin , Li Li , Song Zhengxun , Wang Zuobin
Published: November 2019

Single-cell patterning technology has revealed significant contributions of single cells to conduct basic and applied biological studies in vitro such as the understanding of basic cell functions, neuronal network formation, and drug screening. Unlike traditional population-based cell patterning approaches, single-cell patterning is an effective technology of fully understanding cell heterogeneity by precisely controlling the positions of individual cells. Therefore, much attention is currently being paid to this technology, leading to the development of various micro-nanofabrication methodologies that have been applied to locate cells at the single-cell level. In recent years, various methods have been continuously improved and innovated on the basis of existing ones, overcoming the deficiencies and promoting the progress in biomedicine. In particular, microfluidics with the advantages of high throughput, small sample volume, and the ability to combine with other technologies has a wide range of applications in single-cell analysis. Here, we present an overview of the recent advances in single-cell patterning technology, with a special focus on current physical and physicochemical methods including stencil patterning, trap- and droplet-based microfluidics, and chemical modification on surfaces via photolithography, microcontact printing, and scanning probe lithography. Meanwhile, the methods applied to biological studies and the development trends of single-cell patterning technology in biological applications are also described.
A Schwarz inequality for complex basis function methods in non-Hermitian quantum chemistry
Authors: Thompson Travis H. , Ochsenfeld Christian , Jagau Thomas-C.
Published: November 2019

A generalization of the Schwarz bound employed to reduce the scaling of quantum-chemical calculations is introduced in the context of non-Hermitian methods employing complex-scaled basis functions. Non-Hermitian methods offer a treatment of molecular metastable states in terms of L2-integrable wave functions with complex energies, but until now, an efficient upper bound for the resulting electron-repulsion integrals has been unavailable due to the complications from non-Hermiticity. Our newly formulated bound allows us to inexpensively and rigorously estimate the sparsity in the complex-scaled two-electron integral tensor, providing the basis for efficient integral screening procedures. We have incorporated a screening algorithm based on the new Schwarz bound into the state-of-the-art complex basis function integral code by White, Head-Gordon, and McCurdy [J. Chem. Phys. 142, 054103 (2015)]. The effectiveness of the screening is demonstrated through non-Hermitian Hartree-Fock calculations of the static field ionization of the 2-pyridoxine 2-aminopyridine molecular complex.
Effects of Reynolds number on vortex structure behind a surface-mounted finite square cylinder with AR = 7
Authors: Wang You Qin
Published: November 2019

This paper presents the numerical solutions of flow around a surface-mounted square cylinder of aspect ratio h/d = 7 at Reynolds numbers of 652 and 13 041. The aim is to investigate the effect of the Reynolds number, between its medium-to-high range, on the flow and vortex structure around such a cylinder. The present simulations have successfully reproduced the primary flow, as well as the three-dimensional large-scale vortex structure in the wake of the finite wall-mounted body. The observation of base vortices, tip vortices, and a horseshoe vortex is consistent with previous experimental studies. A dipole wake is captured at the higher Reynolds number, while a quadrupole wake is captured for the lower, indicating that the Reynolds number strongly influences the wake structure. In the near-wake region, by plotting the isosurface of instantaneous second invariant of the velocity gradient, the full-loop structure is observed for the quadrupole wake, while the half-loop structure is observed for the dipole wake. In the far-wake region, a braided vortex structure formed by asymmetric hairpin vortices is observed at both Reynolds numbers and a new wake topology is proposed for flows with a similar geometry.
On the highly unsteady dynamics of multiple thermal buoyant jets in cross flows
Authors: Lappa Marcello
Published: November 2019

Thermal plumes of small scale generated by spatially separated heat sources can form, like atoms in a chemical compound, complex structures of different kinds and with distinct behaviors. The situation becomes even more complex if plumes can interact with imposed vertical shear (a horizontal wind). In this analysis, a “minimal framework” based on the application of a filtering process to the governing balance equations for mass, momentum, and energy (falling under the general heading of “Large Eddy Simulation” approach) is used together with direct numerical simulation to inquiry about the relative importance of buoyancy and vertical shear effects in determining the patterning scenario when highly unsteady dynamics are established (turbulent flow). Emerging patterns range from the flow dominated by a static rising jet produced by the aggregation of plumes that are pushed by horizontal leftward and rightward winds toward the center of the physical domain to convective systems with disconnected thermal pillars of smaller scale, which travel in the same direction of the prevailing wind. The classical sheltering effect, which for flows that are steady “in mean” simply consists of an increased deflection of the leading buoyant jet with respect to the trailing ones, is taken over by a variety of new phenomena, including (but not limited to) fast plume removal-rebirth mechanisms (with local increase in the velocity frequency and shrinkage in the related amplitude), “bubble” formation-rupture, and local departure of the frequency spectrum from the Kolmogorov similarity law.
The intermediate Hamiltonian Fock-space coupled-cluster method with approximate evaluation of the three-body effects
Authors: Musiał Monika , Meissner Leszek , Cembrzynska Justyna
Published: November 2019

The exponential parametrization of the wave function used in the coupled-cluster approaches has proven very successful in the ab initio description of atomic and molecular systems. This concerns first of all the single-reference version of the method that is designed for states dominated by a single Slater determinant. Usually, the coupled-cluster methods with one- and two-body excitation operators in the exponent form the basic computational schemes. The inclusion of three-body effects in the cluster operator to increase the accuracy of the results is numerically expensive, so their approximate evaluation is rather used in practice. In the case of the single-reference coupled-cluster approach, the problem of approximate evaluation of three-body effects in the cluster operator has been well studied, and computational schemes of both noniterative and iterative nature have been proposed. The situation is different in the case of multireference coupled-cluster methods which are required to describe open shell and quasidegenerate states. The multireference approaches in their standard effective Hamiltonian formulations are more complicated and less frequently used in routine calculations; however, one of them, the so-called Fock-space coupled-cluster method, becomes very effective if reformulated within the intermediate Hamiltonian framework. Both the basic version of the method with one- and two-body clusters and the extended one that includes up to three-body operators in the exponent are implemented. The latter approach provides more accurate results, but its relatively high numerical cost limits its applicability. For this reason, going beyond the basic scheme with one- and two-body clusters through an approximate evaluation of the impact of three-body clusters is of great interest. In the paper, we investigate different ways of approximate inclusion of the three-body effects in the Fock-space coupled-cluster method designated for excitation energy calculations.
Flow analysis of a shock wave at pulse ionization: Riemann problem implementation
Authors: Znamenskaya I. , Mursenkova I. , Doroshchenko I. , Ivanov I.
Published: November 2019

An experimental study of the plasma-gas dynamic fluid formed after pulse ionization of the gas flow with a plane shock wave with Mach number 2.2–4.8 is carried out. Nanosecond volume discharge with UV preionization was switched on when the shock moved in a tube channel test section. Energy input occurs in the low-pressure gas volume separated by the shock surface within a time less than 200–300 ns; a single shock wave breaks into three discontinuities in accordance with the 1D Riemann problem solution. The initial (plasma-dynamic) stage of the flow in the nanosecond time range is visualized by glow recording; the supersonic gas processes in the microsecond time range are recorded using high-speed shadow imaging. Quantitative information about the dynamics of the shocks and contact surface (plots of horizontal distance) was obtained within time up to 25 µs. A region with an increased gas-discharge plasma glow intensity, after the discharge electric current termination, was recorded in the time interval from 0.3 to 1.5 µs; it was explained by a jump in gas temperature and density between the new shock wave and the contact discontinuity.
Intermittent locomotion of a self-propelled plate
Authors: Ryu Jaeha , Sung Hyung Jin
Published: November 2019

Many fish and marine animals swim in a combination of active burst and passive coast phases, which is known as burst-and-coast swimming. The immersed boundary method was used to explore the intermittent locomotion of a three-dimensional self-propelled plate. The degree of intermittent locomotion can be defined in terms of the duty cycle (DC = Tb/Tf), which is the ratio of the interval of the burst phase (Tb) to the total flapping period (Tf = Tb + Tc), where Tc is the interval of the coast phase. The average cruising speed (ŪC), the input power (P¯), and the swimming efficiency (η) were determined as a function of the duty cycle (DC). The maximum ŪC arises for DC = 0.9, whereas the maximum η arises for DC = 0.3. The hydrodynamics of the intermittent locomotion was analyzed by examining the superimposed configurations of the plate and the phase map. The characteristics of the flapping motions in the burst and coast phases are discussed. A modal analysis was performed to examine the role of the flapping motion in the propulsion mechanism. The velocity map and the vortical structures are visualized to characterize qualitatively and quantitatively the influence of intermittent locomotion on propulsion.
Ultralow thermal conductivity and high thermoelectric performance of Cu2Se/TiO2 nanocomposite
Authors: Kong Fangfang , Bai Jiang , Zhao Yiwei , Liu Yong , Shi Jing , Wang Ziyu , Xiong Rui
Published: November 2019

In this work, nano-TiO2 particles were introduced into Cu2Se for enhancing thermoelectric (TE) properties. We found that nano-TiO2 can efficaciously decrease the thermal conductivity by increasing the phonon scattering, making it possible to enhance TE performance of Cu2Se to some extent. The minimum κ value was 0.35 W m−1 K−1, and the κL value was as low as 0.23 W m−1 K−1 for the Cu2Se/TiO2 nanocomposites. Further, a high ZT value of ∼1.6 at 1073 K and an average ZT (400 K–1073 K) value of ∼1 were obtained for the Cu2Se/TiO2 nanocomposite (the molar ratio of Ti to Se is 0.1).
Magnetization reversal, damping properties and magnetic anisotropy of L1-ordered FeNi thin films
Authors: Thiruvengadam V. , Singh B. B. , Kojima T. , Takanashi K. , Mizuguchi M. , Bedanta S.
Published: November 2019

L 1 0 -ordered magnetic alloys such as FePt, FePd, CoPt, and FeNi are well known for their large magnetocrystalline anisotropy. Among these, the L10-FeNi alloy is an economically viable material for magnetic recording media because it does not contain rare earth and noble elements. In this work, L10-FeNi films with three different strengths of anisotropy were fabricated by varying the deposition process in a molecular beam epitaxy system. We have investigated magnetization reversal along with domain imaging via a magneto-optic Kerr effect based microscope. It is found that in all three samples, the magnetization reversal happens via domain wall motion. Furthermore, ferromagnetic resonance spectroscopy was performed to evaluate the damping constant (α) and magnetic anisotropy. It was observed that the FeNi sample with a moderate strength of anisotropy exhibits a low value of α∼4.9×10−3. In addition to this, it was found that the films possess a mixture of cubic and uniaxial anisotropies.
Impact of dislocations on the thermal conductivity of gallium nitride studied by time-domain thermoreflectance
Authors: Park Kihoon , Bayram Can
Published: November 2019

GaN thermal conductivity (κGaN) of hydride vapor phase epitaxy grown GaN (HVPE GaN), high nitride pressure grown GaN (HNP GaN), and metal-organic chemical vapor deposition grown GaN on sapphire (GaN/sapphire) and on Si(111) (GaN/Si) are measured as 204.7 (±4.6), 206.6 (±6.8), 191.5 (±10.5), and 164.4 (±3.2) W/m K, respectively, using the time-domain thermoreflectance technique. Dislocation densities (σD) of HVPE GaN, HNP GaN, GaN/sapphire, and GaN/Si are measured as 4.80 (±0.42) × 105, 3.81 (±0.08) × 106, 2.43 (±0.20) × 108, and 1.10 (±0.10) × 109 cm−2, respectively, using cathodoluminescence and X-ray diffraction studies. Impurity concentrations of Si, H, C, and O are measured by secondary ion mass spectroscopy studies. The relationship between κGaN and σD is modeled through a new empirical model κGaN = 210 tanh0.12(1.5 × 108/σD). A modified Klemens's model, where dislocation induced scattering strength is increased, is proposed to explain the experimental rate of decrease in κGaN with increasing σD. Overall, this work reports how κGaN of heteroepitaxially-grown GaN can be estimated based on σD, providing key design guidelines for thermal management in GaN semiconductor devices.
Determination of electronic band structure by electron holography of etched-and-regrown interfaces in GaN p-i-n diodes
Authors: Alugubelli Shanthan R. , Fu Houqiang , Fu Kai , Liu Hanxiao , Zhao Yuji , McCartney Martha R. , Ponce Fernando A.
Published: November 2019

The electrostatic potential variation across etched-and-regrown GaN p-i-n diodes for power electronics has been studied using electron holography in a transmission electron microscope. The potential profiles have been correlated with the composition profiles of Mg, Si, and O obtained by secondary ion mass spectroscopy. Electronic charges obtained from the potential profiles correlate well with the presence of Si and O impurities at regrown interfaces. The overlap of Mg and Si when Mg doped GaN is grown directly over an etched undoped GaN surface results in the formation of a highly doped p-n junction. The introduction of a thin undoped layer over the etched GaN surface prevents the formation of such a junction as the regrowth interface is moved away from the Mg-doped GaN, and results in diodes with improved reverse leakage currents, close to the best values of continuously grown p-i-n diodes. Potential profiles of continuously grown (not etched) p-i-n diodes are compared to those of etched-and-regrown diodes.
Exact moment analysis of transient dispersion properties in periodic media
Authors: Adrover Alessandra , Passaretti Chiara , Venditti Claudia , Giona Massimiliano
Published: November 2019

This paper develops a homogenization approach, based on the introduction of exact local and integral moments, to investigate the temporal evolution of effective dispersion properties of point-sized and finite-sized particles in periodic media. The proposed method represents a robust and computationally efficient continuous approach, alternative to stochastic dynamic simulations. As a case study, the exact moment method is applied to analyze transient dispersion properties of point-sized and finite-sized particles in sinusoidal tubes under the action of a pressure-driven Stokes flow. The sinusoidal structure of the tube wall induces a significant variation of the axial velocity component along the axial coordinate. This strongly influences the transient behavior of the effective axial velocity V z(t) and of the dispersivity Dz(t), both exhibiting wide and persistent temporal oscillations, even for a steady (not-pulsating) Stokes flow. For a pointwise injection of solute particles on the symmetry axis, many interesting features appear: negative values of the dispersion coefficient Dz(t), values of Dz(t) larger than the asymptotic value Dz(∞), and anomalous temporal scaling of the axial variance of the particle distribution. All these peculiar features found a physical and theoretical explanation by adopting simple transport models accounting for the axial and radial variation of the axial velocity field and its interaction with molecular diffusion.
Development of highly efficient NEG pumping system for EBIS
Authors: Kondrashev S. , Beebe E. , Coe B. , Ritter J. , Rodowicz T. , Schoepfer R.
Published: November 2019

Ultrahigh vacuum inside the ion trap volume is crucial for stable and reliable operation of an Electron Beam Ion Source (EBIS). We have developed and tested a compact linear pumping system based on the ZAO Non-Evaporable Getter (NEG) module with high pumping speed and enhanced sorption capacity for all active gases. Due to its minimal transverse dimensions, the system can be mounted adjacent to the ion trap inside a superconducting solenoid bore and will provide a pumping speed of the order of 1000 l/s for all active gases in that area. An externally supplied current (100 A DC) is used to heat the ZAO NEG up to 650 °C for more than 1 h, which is required for pump activation and/or reactivation cycles. The pumping system is being developed for use in the Extended EBIS Upgrade which is presently in progress at BNL. The design of the system and results of multiple tests are presented and discussed.
Thermoelectric property of a one dimensional channel in the presence of a transverse magnetic field
Authors: Yan Chengyu , Pepper Michael , See Patrick , Farrer Ian , Ritchie David A. , Griffiths Jonathan
Published: November 2019

We studied the thermal conduction through a quantum point contact (QPC), defined in a GaAs-AlxGa1−x As heterostructure, in the presence of a transverse magnetic field. A shift in the position of a thermo-voltage peak is observed with increasing field. The position of the thermo-voltage peak follows the Cutler-Mott relation in the small field regime (B < 0.5 T); it starts diverging from the Cutler-Mott relation in the moderate field regime, where a cubic magnetic field term dominates over the trivial quadratic term; eventually, the shift saturates in the large field regime (B > 3.0 T). Our results suggest that additional calibration is necessary when using QPC as thermometry, especially when the transverse magnetic field is applied.