bluuebunny/crossref_metadata_2025 huggingface dataset:
Künstliche Intelligenz in der Endoskopie: Neuronale Netze und maschinelles Sehen – Techniken und Perspektiven
Authors: Schmitz Rüdiger , Werner René , Rösch Thomas
Published: February 2020

Künstliche neuronale Netze als Methoden der künstlichen Intelligenz (KI) können der Endoskopie neue Möglichkeiten eröffnen, etwa im Sinne einer automatischen Polypenerkennung oder der präzisen Vorhersage des histopathologischen Befunds einer Läsion anhand ihres endoskopischen Bildes. Während erste Versuche tatsächlich ein weitreichendes Potenzial erahnen lassen, leiten sich öffentliche und medial transportierte Erwartungen häufig mehr von einer abstrakten Faszination als von der detaillierten Funktionsweise der Methoden ab. Dieser Artikel soll anhand einer selektiven Literaturübersicht ein intuitives Verständnis der Methoden vermitteln und helfen, die Lücke zwischen Funktion und Faszination zu schließen, um Potenzial und Grenzen dieser Techniken im Bereich der Endoskopie realistisch abschätzen zu können.

Mit ihrem Erfolg bei der maschinellen Klassifikation von Bildern haben insbesondere „tiefe neuronale Netze“ der KI nach jahrzehntelanger Forschung zu rasant anwachsendem Interesse verholfen. Wir umreißen kurz die diesbezüglichen Entwicklungen und die Gründe für ihre Bedeutung weit über die Informatik hinaus. Durch den Vergleich von maschinellem und menschlichem Sehen wird ein Verständnis der detaillierten Funktionsweise dieser Methoden und ihrer Erfolge bei Seh-Aufgaben vermittelt. Darauf aufbauend analysieren wir die Funktionsweise jüngst demonstrierter Anwendungen in Hinblick auf methodische Perspektiven und Grenzen, die Aussagekraft bisher erbrachter Leistungsnachweise und die Notwendigkeit weiterer Tests. Zudem geben wir einen Eindruck von weiteren, konkret absehbaren Einzelanwendungen und besprechen, welchen Charakter diese dem Einsatz der künstlichen Intelligenz in der Endoskopie insgesamt geben könnten.
Heart Rate During an Exercise Test and Acute High-intensity Interval
Training in Type 2 Diabetes
Authors: Andrade-Mayorga Omar , Mancilla Rodrigo , Díaz Erik , Alvarez Cristian
Published: February 2020

To describe and compare the acute heart rate changes during an incremental
exercise test and high-intensity interval training (HIIT) in subjects of
different glucose control. Seventy-five adults were allocated into three groups:
Normoglycaemic (NG, n=32), Pre- (PreT2D, n=30) and
Type 2 diabetic (T2D, n=13) subjects. Subjects performed an
incremental cycling test to determine cardiorespiratory fitness
(VO2max), maximum heart rate (HRmax) and HR recovery post maximal
effort, as well as a HIIT cycling session. HR variations are reported as HR pre
(HR-preINT), and post interval (HR-postINT),
percentage of maximum HR (%HRmax), delta of HR increased
(∆HRINT), and delta HR recovery after each interval
(∆HRR). By groups, there was a significant difference for the
%HRmax in 1st and 2nd, but not in intervals
3rd to 10th between Pre-T2D and T2D groups. There were
significant differences for the %HRmax in 1st to
2nd intervals between Pre-T2D and T2D groups. Significant
(P<0.05) differences at some intervals were found for
ΔHRINT, and ΔHRR. These findings suggest that the
HR during an incremental exercise test, and from a typical 10-intervals based
HIIT protocol could be used as an intensity marker for individuals independent
of their glycaemic control.
Blutvolumenmonitoring bei Hämodialysepatienten
Authors: Kron Joachim , Mentzel Ines , Kron Susanne
Published: February 2020

Moderne Dialysegeräte verfügen heute über Monitore zur kontinuierlichen Messung der Veränderung des relativen Blutvolumens. Leider liefert dieses Monitoring nur Informationen über das relative, nicht aber über das absolute Blutvolumen. So kann trotz einer identischen Abnahme des relativen Blutvolumens ein sehr unterschiedliches absolutes Blutvolumen vorliegen. Diese Art des Blutvolumenmonitorings hat die Erwartungen nur unzureichend erfüllt. In diesem Artikel wird eine neue Methode vorgestellt, mit der das absolute Blutvolumen mit den gegenwärtig vorhandenen Dialysegeräten bestimmt werden kann. Allein mit einer Software-Modifikation ließe sich erreichen, dass künftig alle Dialysebehandlungen an einem einzustellenden Zielblutvolumen enden.
6-week High-intensity Interval Training (HIIT) of the Lower
Extremities Improves VO2max of the Upper Extremities
Authors: Marterer Natalie , Menz Verena , Amin Sachin , Faulhaber Martin
Published: February 2020

High intensity interval training (HIIT) is widely used to improve
VO2max. The purpose of this study was to examine if lower
extremity HIIT resulted in improved maximal oxygen uptake (VO2max)
and peak power output (PPO) of the upper extremities. Twenty healthy and trained
participants (11 female and 9 male, VO2max
3160±1175 ml/min) underwent a 6-week HIIT program of the
lower extremities on a cycle ergometer. Before and after the training period a
maximal cycle ergometry (CE) and a maximal hand crank ergometry (HCE) were
conducted to determine VO2max and PPO. Additionally, hematological
parameters were determined. Increases in VO2max of the lower
extremities (3160±1175 to 3449±1231 ml/min,
p<0.001, η2p=0.779) as well as of the upper
extremities (2255±938 to 2377±1015 ml/min,
p=0.010, η2p=0.356) from pre- to post-test
were found. PPO of the lower extremities increased (243±95 to
257±93 W, p<0.001,
η2p=0.491), whereas it remained unchanged for the
upper extremities (103±50 to 108±54 W, p=0.209,
η2p=0.150). All hematological parameters
increased. The results demonstrate that VO2max of the upper
extremities increased after 6-weeks of cycling HIIT. However, upper body PPO was
unchanged.
Faster and Healthier: Relationship between Telomere and Performance
in Master Athletes
Authors: Sousa Caio Victor , Silva Aguiar Samuel , Deus Lysleine Alves , Barbosa Lucas Pinheiro , dos Santos Patrick Anderson , Neves Rodrigo Vanerson Passos , Maciel Larissa Alves , Moraes Milton Rocha , Moreira Sérgio Rodrigues , Grubert Campbell Carmen Sílvia , Andrade Rosangela Vieira , dos Santos Rosa Thiago , Simoes Herbert Gustavo
Published: February 2020

Aging is associated with increased oxidative stress, chronic inflammation, and
decreased telomere length (TL). However, the lifestyle of master athletes can
lead to a reduced risk of these conditions, and thus attenuates aging and
performance deterioration. We aimed to analyze the relationships between TL and
relative performance (RP), and their relation to adiposity, oxidative stress,
and inflammation in endurance (END) and sprint/power (SPW) master
athletes (MAs). Twenty-two world-class MAs visited the laboratory for anamnesis,
anthropometrics, and blood sampling. Inflammatory and oxidative stress
parameters were assessed using commercial kits. Relative TL was determined in
leukocytes through qPCR analyses. A positive association was observed between RP
and TL in both groups (SPW: r=0.641; END: r=0.685)
and the whole sample (r=0.594). The IL6/IL10 ratio
presented an inverse correlation with RP in the whole sample
(r=–0.580). Body mass index also demonstrated a negative
correlation with TL for the END group (r=–0.690) and the
whole sample analysis (r=–0.455). Moreover, the
IL6/IL10 ratio was negatively associated with strength/power
training hours (r=–0.464), whereas the CAT/TBARS
ratio was negatively associated with aerobic training hours
(r=–0.482). In conclusion, TL of MAs was associated with
RP regardless of the training model (endurance or sprint/power), and
inflammation and adiposity were associated with shorter telomeres.
Neuauflage „Dialyse auf Reisen“
Authors: Schrooten Charlotte
Published: February 2020

Ein Tapetenwechsel tut immer gut! Dank der Feriendialyse ist eine optimale Versorgung auch am Urlaubsort garantiert. Urlaub in den Bergen oder am Meer? In der Broschüre „Dialyse auf Reisen 19/20“, die diesen Herbst vom Verband Deutsche Nierenzentren (DN) e. V. in der 16. Auflage herausgebracht wurde, finden nierenkranke Patienten rund 500 aktuelle Adressen von Dialysepraxen in Deutschland und dem Ausland und können so den nächsten Urlaub sorglos planen.
Pharmacogenetic Testing in Depressed Patients and Interdisciplinary
Exchange between a Pharmacist and Psychiatrists Results in Reduced
Hospitalization Times
Authors: Bättig Victor A. D. , Roll Sibylle C. , Hahn Martina
Published: February 2020

Introduction Pharmacogenetics (PGx) is a well-researched tool to
improve pharmacotherapy. So far, it has not been implemented into daily
practice in Germany. In psychopharmacology, substantial benefit can be
expected by using PGx due to the excessive CYP metabolism of the
psychotropic drugs as well as already discovered target polymorphisms
(e. g., serotonin receptor).

Methods An evaluation of a naturalistic pharmacist-led pilot
implementation of PGx testing in a psychiatric hospital in patients
undergoing inpatient treatment for major depressive disorder was conducted.
Length of stay, number of antidepressant switches, and rehospitalization
rates were analyzed. A PGx-tested intervention cohort of n=49 was
retrospectively compared to a control cohort of n=94 patients.

Results The intervention cohort showed significantly shorter stays
than the control, after correction of the length of hospital stay and the
time to genotyping results (mean intervention: 36.3 d (SD: ±19.3 d);
control: 46.6 d (±19.1 d); p=0.003). Antidepressant-
naïve patients had the largest benefit from the PGx testing
(intervention: 24.7 d (±13.5 d); control: 50.2 d (±22.5 d);
p < 0.001. The number of antidepressant switches during the entire
stay did not differ between the groups: 0.41 (0.64) vs. 0.21 (0.46);
p=0.063 [95% CI −0.01–0.40]).

Discussion Depressed patients, especially treatment-naïve,
seem to benefit from PGx testing prior to treatment. Although the results of
this retrospective evaluation are promising, more systematic prospective
studies are needed to assess the effect of PGx testing on the treatment of
major depressive disorder.
Pharmacokinetics, Tissue Distribution, and Excretion Study of Cajanonic Acid A in Rats by UPLC-MS/MS
Authors: Zhang Li , Chen Rui , Ban Yujuan , Cai Jin , Peng Jingang , Huang Jing , Wang Jianta , Chen Wenzhang , Gao Xiuli , Zhou Xunrong , Tang Lei
Published: February 2020

Cajanonic acid A (CAA), a prenylated stilbene derivative extracted from the leaves of pigeon pea (Cajanus cajan), has been reported to possess inhibitory activity on the peroxisome proliferator-activated receptor gamma (PPARγ) and protein tyrosine phosphatase 1B (PTP1B). Its hypoglycemic activity in rats is comparable to that of the approved antidiabetic agent rosiglitazone. Therefore, CAA is a potential candidate for the treatment of type 2 diabetes and a lead compound for the discovery of novel hypoglycemic drugs. To achieve a thorough understanding of the biological behavior of CAA in vivo, our current study was designed to investigate the pharmacokinetics, bioavailability, distribution, and excretion of CAA in rats by UPLC-MS/MS. Chromatographic separation was performed on BEHC18 column (2.1 mm × 50 mm, 1.7 µm). Quantification was performed under the negative ion mode by using single reaction monitoring (SRM) of the transitions of m/z 353.14 → 309.11 for CAA and m/z 269.86 → 224.11 for genistein, respectively. Standard calibration curve showed excellent linearity (r2 > 0.99) within the range of 2 – 800 ng/mL. The accuracies and precisions were within the acceptance limits (all < 20%). CAA was quickly absorbed into bloodstream and distributed rapidly and widely to various tissues. The excretion ratio of CAA in the 3 main pathways via bile, feces, and urine was only 5.17%. These results indicate that CAA was quickly and thoroughly metabolized in vivo and excreted mainly as metabolites.
Metal-Free Halogenation of N-Substituted Enaminoesters and Enaminones: A Facile Access to Functionalized α,α-Dihaloimines
Authors: Qiu Changfu , Yu Heshui , Qiu Chuanjiang , Li Fangyi , Suo Tongchuan , Wang Chunhua , Bie Songtao , Li Zheng
Published: February 2020

An efficient and general method for the synthesis of functionalized α,α-dihaloimines via halogenation of N-substituted enaminoesters and enaminones is described. This reaction, in which both α,α-dihaloimines and mixed α,α-dihaloimines could be achieved in good to excellent yields, is believed to proceed via an α-monohalogenated enamine intermediate. This synthetic method features no use of transition metals, readily accessible substrates, mild reaction conditions, simple and safe operation, and gram scale synthesis. Furthermore, the synthetic utility of the products was demonstrated by their efficient transformations to further useful nitrogen-containing heterocycles and building blocks.
Full Endoscopic Technique for High-Grade Up-Migrated Lumbar Disk Herniation via a Translaminar Keyhole Approach: Preliminary Series and Technical Note
Authors: Lin Guang-Xun , Park Cheul-Woong , Suen Tsz-King , Kotheeranurak Vit , Jun Su-Gi , Kim Jin-Sung
Published: February 2020

Background and Study Aims Technically and anatomically, accessing a high-grade migrated lumbar disk herniation (LDH) using traditional full endoscopic lumbar diskectomy (FELD) approaches (either transforaminal or interlaminar) is challenging. The objective of this study was to present an effective and safe surgical approach for high-grade up-migrated LDH by translaminar FELD.

Patients and Methods Thirteen patients with soft high-grade up-migrated LDH treated with a translaminar FELD between May 2015 and July 2018 were reviewed in this study. Five of these patients had very high-grade up-migration. Clinical outcomes were assessed including preoperative and postoperative visual analog scale (VAS) for back and leg pain, Oswestry Disability Index (ODI), and MacNab criteria.

Results Overall, 7 of the 13 patients had disk-fragment migration at L4–L5: three at L5–S1, two at L3–L4, and the remaining one at L2–L3. In all cases, the highly up-migrated LDH was removed successfully through the translaminar approach, as confirmed by postoperative magnetic resonance imaging. The improvements of VAS for back and leg pain were 4.5 ± 0.9 to 1.3 ± 1.3 and 7.1 ± 1.0 to 1.6 ± 0.7, respectively (both p < 0.05). The ODI decreased from preoperative 41.9 ± 6.0 to postoperative 13.0 ± 4.1 (p < 0.05). According to the MacNab criteria, the satisfaction rate was 92.3% (excellent or good outcomes). None of the patients experienced any perioperative complications or recurrence during the follow-up period.

Conclusion Although full endoscopic technique via the translaminar keyhole route may not be used as a routine surgical approach, it could serve as a feasible alternative method for patients with highly up-migrated disk herniation.
A Rare Case of Gastric Volvulus Post Laparoscopic Gastric Greater Curvature Plication
Authors: Kachi Antoine , Chidiac Khalil , Khaled Charif
Published: February 2020

Gastric volvulus is a rare entity. Its diagnosis remains tricky and challenging. In recent years, the incidence of gastric volvulus has shown a rise in postbariatric surgery patient. Several cases were reported of gastric remnant volvulus post-laparoscopic sleeve gastrectomy and laparoscopic gastric bypass. Laparoscopic gastric greater curvature plication is a new and experimental restrictive technique for weight loss. Several of its complications were reported in the literature but never was a case of volvulus postgastric plication reported, as far as we know. We present this rare case with an atypical presentation and go through similar cases in the literature.
Medial Meniscus Scaffold Implantation in Combination with Concentrated Bone Marrow Aspirate Injection: Minimum 3-Year Follow-up
Authors: Akkaya Mustafa , Şimşek Mehmet Emin , Gürsoy Safa , Çay Nurdan , Bozkurt Murat
Published: February 2020

The objective of this study is to show the short-term clinical and radiological outcomes of concentrated bone marrow aspirate (CBMA) injection administered in combination with medial meniscus scaffold implantation. Twenty-three patients who received intra-articular CBMA injection in combination with polyurethane-based medial meniscus scaffold implantation were evaluated within the scope of this study. The International Knee Documentation Committee (IKDC) questionnaire and the Knee injury and Osteoarthritis Outcome Score (KOOS) were used to evaluate the results, and the visual analog scale was used to assess the pain scores. Magnetic resonance imaging (MRI) scans were obtained in the preoperative period and at postoperative months 1, 12, 24, and 36 to assess the scaffold position as well as chondral degeneration/damage in a comparative manner. MRI assessment was performed by using the modified Outerbridge scale for cartilage and the Genovese scoring system for the meniscal implant. Twenty-three patients who were included in the study were evaluated for a mean follow-up period of 38.3 months. Patients exhibited statistically significant improvement according to all scoring data from the preoperative period until the follow-up period. The mean postoperative extrusion at year 3 was 2.39 mm (distribution 2.30–2.56 mm). There was no significant difference in the distribution of the degree of chondral damage between the preoperative and 3-year follow-up periods. Four patients did not show any improvement nor had lower scores according to the assessment. Medial meniscus scaffold implantation combined with intra-articular CBMA injection resulted in a significant improvement in all functions and pain scores as well as a statistically significant clinical improvement in IKDC and KOOS values in the short-term follow-up. The Level of evidence for this study is IV.
Novel Mutation in ATP6V1A Gene with Infantile Spasms in an Indian Boy
Authors: Kadwa Razia A.
Published: February 2020

A 7-month-old boy with a novel mutation in ATP6V1A gene is described. The ATP6V1A gene has been recently identified to be associated with epileptic encephalopathies. Clinical features in this patient are different from cases reported so far, thus broadening the spectrum of ATP6V1A-associated epileptic encephalopathy.
Improving on transfer entropy-based network reconstruction using time-delays: Approach and validation
Authors: Sipahi Rifat , Porfiri Maurizio
Published: February 2020

Transfer entropy constitutes a viable model-free tool to infer causal relationships between two dynamical systems from their time-series. In an information-theoretic sense, transfer entropy associates a cause-and-effect relationship with directed information transfer, such that one may improve the prediction of the future of a dynamical system from the history of another system. Recent studies have proposed the use of transfer entropy to reconstruct networks, but the inherent dyadic nature of this metric challenges the development of a robust approach that can discriminate direct from indirect interactions between nodes. In this paper, we seek to fill this methodological gap through the cogent integration of time-delays in the transfer entropy computation. By recognizing that information transfer in the network is bound by a finite speed, we relate the value of the time-delayed transfer entropy between two nodes to the number of walks between them. Upon this premise, we lay out the foundation of an alternative framework for network reconstruction, which we illustrate through closed-form results on three-node networks and numerically validate on larger networks, using examples of Boolean models and chaotic maps.
Bispectral unfolding of the skewness of correlated additive and multiplicative noise processes
Authors: Monahan Adam H.
Published: February 2020

Correlated additive and multiplicative (CAM) noise processes are well-established as general “null hypothesis” models of non-Gaussian variability in atmospheric and oceanic quantities. In this study, analytic expressions for the bispectral density (which partitions the third statistical moment into triad frequency interactions in a manner analogous to the partitioning of variance by the spectral density) are developed for discrete and continuous-time CAM processes. It is then demonstrated that under lowpass filtering, while the absolute skewness of a discrete-time CAM process may increase or decrease with decreasing cutoff frequency, the absolute skewness of continuous-time CAM processes decreases monotonically. This second result provides a test to assess the degree to which an observed time series is consistent with continuous-time CAM dynamics.
Quantitative coordination evaluation for screening children with Duchenne muscular dystrophy
Authors: An Jian , Xie Zhiying , Jia Fan , Wang Zhaoxia , Yuan Yun , Zhang Jue , Fang Jing
Published: February 2020

As the potential for a treatment of Duchenne muscular dystrophy (DMD) grows, the need for methods for the early diagnosis of DMD becomes more and more important. Clinical experiences suggest that children with DMD will show some lack of motor ability in the early stage when compared with children at the same age, especially in balance and coordination abilities. Is it possible to quantify the coordination differences between DMD and typically developing (TD) children to achieve the goal of screening for DMD diseases? In this study, we introduced a Local Manifold Structure Mapping approach in phase space and extracted a novel index, relative coupling coefficient (RCC), from gait pattern signals, which were acquired by wearable accelerometers to evaluate the coordination of children with DMD during a walking task. Furthermore, we compared the RCC of 100 children with DMD and 100 TD children in four different age groups and verified the feasibility and reliability of the proposed indices to distinguish children with TD from DMD. T-test results show that, for all age groups, children of the same age with DMD and TD show significant differences in RCC (p < 0.001). Moreover, RCC comprehensively reflects that the coordination ability of DMD patients under walking tasks gradually decreases with age, which is consistent with clinical experience. As a functional biomarker extracted in the phase space of the gait data, the proposed coupling degree index RCC could sensitively distinguish between DMD and TD children at the same age and provide alternative insights and potentially valuable tools for the screening of DMD.
Physical chemistry of the TiN/Hf0.5Zr0.5O2 interface
Authors: Hamouda W. , Pancotti A. , Lubin C. , Tortech L. , Richter C. , Mikolajick T. , Schroeder U. , Barrett N.
Published: February 2020

Ferroelectric hafnia-based thin films are promising candidates for emerging high-density embedded nonvolatile memory technologies, thanks to their compatibility with silicon technology and the possibility of 3D integration. The electrode–ferroelectric interface and the crystallization annealing temperature may play an important role in such memory cells. The top interface in a TiN/Hf0.5Zr0.5O2/TiN metal–ferroelectric–metal stack annealed at different temperatures was investigated with X-ray photoelectron spectroscopy. The uniformity and continuity of the 2 nm TiN top electrode was verified by photoemission electron microscopy and conductive atomic force microscopy. Partial oxidation of the electrode at the interface is identified. Hf is reduced near the top interface due to oxygen scavenging by the top electrode. The oxygen vacancy (VO) profile showed a maximum at the top interface (0.71%) and a sharp decrease into the film, giving rise to an internal field. Annealing at higher temperatures did not affect the VO concentration at the top interface but causes the generation of additional VO in the film, leading to a decrease of the Schottky Barrier Height for electrons. The interface chemistry and n-type film doping are believed to be at the origin of several phenomena, including wake-up, imprint, and fatigue. Our results give insights into the physical chemistry of the top interface with the accumulation of defective charges acting as electronic traps, causing a local imprint effect. This may explain the wake-up behavior as well and also can be a possible reason of the weaker endurance observed in these systems when increasing the annealing temperature.
Resistive switching behaviors and mechanisms of HfS2 film memory devices studied by experiments and density functional theory calculations
Authors: Li Naifeng , Wang Yue , Sun Haifeng , Hu Junjie , Zheng Maoyuan , Ye Sihao , Wang Qi , Li Yingtao , He Deyan , Wang Jiatai , Zhang Guangan , Qi Jing
Published: February 2020

Energy band diagrams are widely utilized to explain the switching mechanism of resistance random access memory (RRAM). However, a precise and quantitative band theory is still lacking in this field. Although HfS2 has good applications in many fields because of its good electrical and optical properties, its applications in RRAM have seldom been reported. In this work, the exfoliated nanosheets of HfS2 were utilized to fabricate memory devices with a structure of Pt/Al/HfS2/p+-Si, which show typical bipolar resistive switching behavior with high switching voltage and a small ratio of high and low resistive states (R-ratio). According to the density functional theory (DFT) calculation results of energy band diagrams, instead of conductive filament formation in other resistive switching materials, the doping of sulfur vacancy (VS) of 3.8% is already enough to change the whole HfS2 layer from the semiconductor to the metal. The transition is caused by the change in the VS doping concentration from low to high, which is the result of the generation and movement of VS under an electric field. The DFT also calculated that HfS2 devices utilizing Indium Tin Oxide as the bottom electrode can show bipolar resistive switching behavior with lower switching voltage and a higher R-ratio than those utilizing p+-Si, which is confirmed by the experimental results. The DFT calculation can be utilized for both explaining the switching mechanism and designing the device structure to optimize the switching characteristics.
Configuration interaction approaches for solving quantum impurity models
Authors: Jin Zuxin , Dou Wenjie , Subotnik Joseph E.
Published: February 2020

We develop several configuration interaction approaches for characterizing the electronic structure of an adsorbate on a metal surface (at least in model form). When one can separate the adsorbate from the substrate, these methods can achieve a reasonable description of adsorbate on-site electron-electron correlation in the presence of a continuum of states. While the present paper is restricted to the Anderson impurity model, there is hope that these methods can be extended to ab initio Hamiltonians and provide insight into the structure and dynamics of molecule-metal surface interactions.
A semiconductor topological photonic ring resonator
Authors: Jalali Mehrabad M. , Foster A. P. , Dost R. , Clarke E. , Patil P. K. , Farrer I. , Heffernan J. , Skolnick M. S. , Wilson L. R.
Published: February 2020

Unidirectional photonic edge states arise at the interface between two topologically distinct photonic crystals. Here, we demonstrate a micrometer-scale GaAs photonic ring resonator, created using a spin Hall-type topological photonic crystal waveguide. Embedded InGaAs quantum dots are used to probe the mode structure of the device. We map the spatial profile of the resonator modes and demonstrate the control of the mode confinement through tuning of the photonic crystal lattice parameters. The intrinsic chirality of the edge states makes them of interest for applications in integrated quantum photonics, and the resonator represents an important building block toward the development of such devices with embedded quantum emitters.
Fast modeling of turbulent transport in fusion plasmas using neural networks
Authors: van de Plassche K. L. , Citrin J. , Bourdelle C. , Camenen Y. , Casson F. J. , Dagnelie V. I. , Felici F. , Ho A. , Van Mulders S. ,   JET Contributors
Published: February 2020

We present an ultrafast neural network model, QLKNN, which predicts core tokamak transport heat and particle fluxes. QLKNN is a surrogate model based on a database of 3 × 108 flux calculations of the quasilinear gyrokinetic transport model, QuaLiKiz. The database covers a wide range of realistic tokamak core parameters. Physical features such as the existence of a critical gradient for the onset of turbulent transport were integrated into the neural network training methodology. We have coupled QLKNN to the tokamak modeling framework JINTRAC and rapid control-oriented tokamak transport solver RAPTOR. The coupled frameworks are demonstrated and validated through application to three JET shots covering a representative spread of H-mode operating space, predicting the turbulent transport of energy and particles in the plasma core. JINTRAC–QLKNN and RAPTOR–QLKNN are able to accurately reproduce JINTRAC–QuaLiKiz Ti,e and ne profiles, but 3–5 orders of magnitude faster. Simulations which take hours are reduced down to only a few tens of seconds. The discrepancy in the final source-driven predicted profiles between QLKNN and QuaLiKiz is on the order of 1%–15%. Also the dynamic behavior was well captured by QLKNN, with differences of only 4%–10% compared to JINTRAC–QuaLiKiz observed at mid-radius, for a study of density buildup following the L–H transition. Deployment of neural network surrogate models in multi-physics integrated tokamak modeling is a promising route toward enabling accurate and fast tokamak scenario optimization, uncertainty quantification, and control applications.
WGT: A mesoscale-informed reactive burn model
Authors: Reynaud M. , Sorin R. , Dubois V. , Desbiens N.
Published: February 2020

Polymer bounded explosives (PBXs) consist of energetic crystals coated with a polymer binder. These materials exhibit a highly heterogeneous microstructure. The initiation of the detonation phenomenon in PBXs is believed to be generated at the microstructure scale through hotspots. Hence, many of the explosives properties (initiation, desensitization, etc.) are understood as a direct consequence of their microstructure. Mesoscale modeling directly addresses the physics of hotspot formation. Unfortunately, high computational cost prevents their use on laboratory-sized and large scale experiments. In practice, continuum-scale models remain mandatory. We describe a new reactive burn model, named WGT, aiming to represent, at the continuum scale, some of the complexity of the PBX’s microstructure. The initiation regime is driven by the shock temperature and results from surrogate modeling of the kinetics of a heterogeneous nucleation and growth model. The other regimes follow the formulation of the WHS2D2 reactive burn model and are driven by the local temperature. This model was calibrated on experimental results for PBX 9502 available in the literature, such as detonation velocity–curvature laws, Pop-plot data, or embedded electromagnetic particle velocity gauges. The model was also tested against desensitization and propagation data.
Deep ultraviolet monolayer GaN/AlN disk-in-nanowire array photodiode on silicon
Authors: Aiello Anthony , Wu Yuanpeng , Mi Zetian , Bhattacharya Pallab
Published: February 2020

Extreme confinement of carriers in GaN layers of thickness of the order of a monolayer leads to a large quantum confinement energy and very large electronic and optical bandgaps. We have exploited this to realize a photodiode with AlN nanowire arrays, grown on silicon substrates by plasma-enhanced molecular beam epitaxy, wherein multiple ∼2 monolayer disks are inserted as the light absorbing region. Photoluminescence and photocurrent spectra confirm the optical gaps of the monolayer GaN. The photocurrent spectra show a peak at ∼240 nm in the deep-ultraviolet region of the optical spectrum. The dark current of the photodiodes is ∼10 nA at −6 V at room temperature. The peak quantum efficiency is 0.6%, and the noise-equivalent power is estimated to be 4.3 × 10−11W/Hz1/2. The bandwidth of the device is estimated to be limited to ∼3 MHz by the series resistance and diode capacitance.
Evolution of InAs quantum dots and wetting layer on GaAs (001): Peculiar photoluminescence near onset of quantum dot formation
Authors: Kumar Rahul , Maidaniuk Yurii , Saha Samir K. , Mazur Yuriy I. , Salamo Gregory J.
Published: February 2020

InAs quantum dots (QDs) have been grown on a GaAs (001) substrate in the subcritical region of InAs coverage for transition from a 2-dimensional (2D) to a 3-dimensional growth mode. Evolution of QDs and the corresponding wetting layer (WL) with InAs coverage has been investigated. Under specific growth conditions, quantum dot formation was observed only in samples where InAs coverage is more than 1.48 ML. The QD density increases sharply with InAs deposition initially but slows down with increased coverage. Photoluminescence (PL) shows the existence of a third peak, other than QD and WL peaks, at the low energy side of the WL peak, which is named the precursor peak. Evidence is presented supporting the theory that this peak is due to 2D InAs islands on a monolayer of InAs, which are small enough to localize excitons. Meanwhile, the WL peak is due to larger InAs islands under high compressive strain. During QD formation, the WL peak energy increases with the increase in InAs deposition. This is due to the sudden transfer of material from the bigger size of InAs islands to the QD. Our results show that the QD, WL, and precursor peaks coexist near the onset of QD formation. The power dependence of the three PL peaks is evident, which supports to our conclusion.
A comprehensive numerical analysis of cross-flow vortex-induced vibrations for top tension risers under different flows
Authors: Liu Guijie , Li Haiyang , Qiu Zhaozun , Li Zhixiong
Published: February 2020

In this paper, the cross-flow vortex-induced vibration (VIV) response of a top tension riser under different flow fields are comprehensively studied using a numerical simulation model based on time domain analysis. A semi-empirical time-domain analysis model that considers the fluid-structure interaction problem in the riser vibration process is proposed and verified by comparison with the previous experimental results. The influence of the flow velocity, the spanwise length of the flow field, and other factors on the VIV amplitude and frequency characteristics of the riser is analyzed in detail. The results show that the VIV response of the riser exhibits obvious multi-modal characteristics, which are accompanied by modal transition, lock-in vibration, synchronous vibration, etc., and the region where the lock-in or synchronous vibration occurs is exactly the region where the crest of the amplitude curve locates. Besides, the VIV intensity of the riser in the stepped flow and uniform flow fields show a tendency of fluctuating increase with the increase of the flow velocity and spanwise length of the flow field, while the VIV intensity of the riser in shear flow is positively correlated with the flow velocity and spanwise length of the flow field. The present study may provide a reference for the prediction of VIV of marine riser in the complex current environment.
Room-temperature deposition of ferroelectric HfO2-based films by the sputtering method
Authors: Mimura Takanori , Shimizu Takao , Uchida Hiroshi , Funakubo Hiroshi
Published: February 2020

Ferroelectricity has been demonstrated in epitaxial 7%Y-doped HfO2 (0.07YO1.5–0.93HfO2, YHO7) films grown by the RF magnetron sputtering method at room temperature without any subsequent annealing. The x-ray diffraction patterns of such films suggested that the decrease in RF power and in the partial oxygen pressure changes the crystal structures of the films from the monoclinic phase to the tetragonal/orthorhombic phase. Clear polarization-electric-field (P–E) hysteresis loops were observed for these epitaxial films with the tetragonal/orthorhombic phase. The obtained remanent polarization (Pr) and coercive field (Ec) values were 14.5 and 12.8 μC/cm2 and 2300 and 2200 kV/cm for the epitaxial films on (111) indium tin oxide (ITO)//(111) yttria-stabilized zirconia (YSZ) and (100)ITO//(100)YSZ substrates, respectively. Moreover, ferroelectricity was also observed in room-temperature-deposited polycrystalline YHO7 films prepared on Pt/TiOx/SiO2/(100)Si, crystallized ITO/soda glass, and amorphous ITO/polyethylene terephthalate substrates, namely, crystalline ferroelectric HfO2-based films were prepared at room temperature on various substrates, including organic flexible substrates, by using the RF magnetron sputtering method. The present results open a path to novel applications of ferroelectric HfO2-based films such as ferroelectric flexible memory.
Glass transition temperature of single-chain polystyrene particles end-grafted to oxide-coated silicon
Authors: Li Yawei , Lin Decai , Xu Jianquan , Zhou Xianjing , Zuo Biao , Tsui Ophelia K. C. , Zhang Wei , Wang Xinping
Published: February 2020

A method based on the PeakForce QNM atomic force microscopic (AFM) adhesion measurement is employed to investigate the glassy dynamics of polystyrene (PS) single-chain particles end-grafted to SiO2—Si substrates with different diameters, D0, of 3.4 nm–8.8 nm and molar masses, Mn, of 8–123 kg/mol. As temperature was increased, the adhesion force, Fad, experienced by the AFM tip on pulling off the single chains after loading demonstrated a stepwise increase at an elevated temperature, which we identified to be Tg based on previous works. Our result shows that Tg of our grafted single chains increases with Mn in a manner consistent with the Fox–Flory equation, but the coefficient quantifying the Mn dependence of Tg is only (36 ± 6)% the value of bulk PS. In addition, the value of Tg in the Mn → ∞ limit is about 25 °C below the bulk Tg but more than 15 °C above that of (untethered) PS nanoparticles with D0 ≈ 100 nm suspended in a solution. Our findings are consistent with Tg of our single chains being dominated by simultaneous effects of the interfaces, which depress Tg, and end-grafting, which enhances Tg. The latter is believed to exert its influence on the glass transition dynamics by a mechanism reliant on chain connectivity and does not vary with chain length.
Origin and anomalous behavior of dominant defects in 4H-SiC studied by conventional and Laplace deep level transient spectroscopy
Authors: Gelczuk Ł. , Dąbrowska-Szata M. , Kolkovsky Vl. , Sochacki M. , Szmidt J. , Gotszalk T.
Published: February 2020

Several deep level defects were observed by conventional deep level transient spectroscopy (DLTS) and high-resolution Laplace DLTS (LDLTS) in n-type 4H-SiC junction barrier Schottky diodes. We have shown that the broad DLTS peak labeled Z1/2 has, in fact, two components, Z1 and Z2, with activation enthalpies for electron emission of 0.63 eV and 0.68 eV, respectively. The reorientation process between these two components was observed. A combination of double-correlated DLTS and LDLTS demonstrated an anomalous reduction of the emission rate and an increase of the activation enthalpy of Z2 with an increase of the reverse bias applied to the diode. The possible explanation of this phenomenon could be correlated with a tensile stress in epitaxial SiC layers. The results observed are discussed in the frame of the model that correlates Z1 and Z2 with carbon vacancies (VC), located at hexagonal (h) and cubic (k) lattice sites, respectively. We also discussed the origin of other traps E0–E5 with particular emphasis on a N-related shallow donor level located at 0.04 eV below the conduction band, which has never been previously reported by DLTS studies.
Frictional properties of polymer binders for Li-ion batteries
Authors: Nguyen Quang Dang , Chung Koo-Hyun
Published: February 2020

In this work, the frictional properties of various polymer binders were studied using atomic force microscopy to enhance the mechanical integrity of the silicon (Si) anode for lithium-ion batteries (LIBs). The binders used include polyacrylic acid (PAA), polyacrylonitrile (PAN), polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC), and polyvinylidene fluoride. The interfacial shear strength of the polymer binder was determined against Si to understand the contact shearing and sliding behaviors. The results showed that due to electrolyte immersion, the intrinsic interfacial shear strengths and pressure coefficients decreased by factors of 1.3–7.5 and 1.6–23.7, respectively. Decreases in mechanical and adhesion properties in the electrolyte may be responsible for the decrease in the frictional properties. The results also showed that topography-induced friction fluctuation became significant in the electrolyte due to an increase in the slope of the surface asperities, which is associated with polymer swelling. The Si anodes of LIBs containing polymer binders with relatively large intrinsic interfacial shear strengths and pressure coefficients in the electrolyte (PAA, PAN, PVA, and CMC) had high capacity retention. Given that a polymer binder with high interfacial shear strength helps maintain the mechanical integrity of the Si anode, PAA with high intrinsic interfacial shear strength may be preferred when the stress level is low during lithiation, while PVA with a large pressure coefficient may be advantageous when the stress level is high during lithiation. The outcome of this work suggests that the interfacial shear strength is a better polymer binder performance indicator than just considering mechanical and adhesion properties.
Direct observation of ultrafast electrons generated by high-intensity laser-matter interaction
Authors: Galletti M. , Bisesto F. G. , Anania M. P. , Ferrario M. , Pompili R. , Poyé A. , Tikhonchuk V. , Zigler A.
Published: February 2020

High intensity ultrashort laser pulses interacting with thin solid targets are able to produce energetic protons and ions by means of extremely large accelerating fields, generated by escaping electrons. The characterization of such electrons is thus a key factor for the understanding of the accelerating potential temporal evolution. Here, we present temporally resolved measurements of the ultrafast escaping electron component. The charge, electric field, and temporal duration of the emitted ultrafast electron beams are determined using temporal diagnostics with a 100 fs temporal resolution. Experimental evidence of scaling laws for the ultrafast electron beam parameters with respect to the incident laser pulse energy is retrieved and compared with theoretical models, showing an excellent agreement.
A study on mixing performance of dean flows through spiral micro-channel under various effects
Authors: Ngo I. L. , Lai T. K. , Choi H. J. , Le H. T. T. , Kim G. M. , Dang T. D.
Published: February 2020

This paper reports a parametric study on mixing performance of dean flows in spiral micro-channels using the finite element method. Many important parameters such as the Reynolds number (Re), Peclet number (Pe), flow rate ratio between two species flows (α), and ratio of diffusion coefficient (β) were examined for enhancing mixing efficiency (ηmix). The numerical results matched well with those predicted by the theoretical model. In addition, mixing efficiency of dean flows in the spiral micro-channel generally increased with increasing Re, particularly at low Pe. This is in contrast to results obtained for straight micro-channels with the same channel length. Mixing efficiency (ηmix) was affected significantly by the Pe number ranging from 103 to 4 × 104, and it increases with a decrease in Pe. In addition, ηmix varied remarkably with α, and the worst point, at which the ηmix decreases by 50%, occurs when α is around 2.0. Otherwise, ηmix is shown to be influenced slightly by β. Furthermore, a new generalized correlation was proposed for predicting the pressure drop throughout a spiral micro-channel effectively. These results provide good suggestions for optimizing mixing efficiency of dean flows in spiral micro-channels, which can be used for further biological and chemical analyses.
Experimental investigation of ionization front propagating in a 28 GHz gyrotron beam: Observation of plasma structure and spectroscopic measurement of gas temperature
Authors: Tabata Kuniyoshi , Harada Yuki , Nakamura Yusuke , Komurasaki Kimiya , Koizumi Hiroyuki , Kariya Tsuyoshi , Minami Ryutaro
Published: February 2020

Atmospheric millimeter-wave discharge was investigated experimentally using a 28 GHz gyrotron. The propagation velocity of an ionization front, plasma structure, and vibrational and rotational temperatures of nitrogen molecules were measured at a beam intensity lower than 1.0 GW/m2, which is below the breakdown threshold. Results show that the propagation velocity of an ionization front increased monotonically with beam intensity and decreased with ambient pressure. In addition, four typical plasma structures having different space occupancies were observed. Furthermore, at any beam intensity below 0.5 GW/m2, the vibrational temperature was found to be saturated at about 6000 K. The corresponding electron number density is almost equal to the cut-off density. Finally, it was suggested that the propagation velocity depends on the plasma space occupancy.
Shark and ray community structure in a turbid, nearshore coral reef habitat
Authors: Yon Arthur , Meekan Mark G. , Andrzejaczek Samantha , Martinez Sarah , Speed Conrad W.
Published: February 2020

The coastline of northern Australia may be a refuge for elasmobranchs threatened or extirpated from much of their former ranges across South-East Asia. In this study, we used baited remote underwater video stations to survey the abundance, size and assemblage of elasmobranchs in the Cobourg Marine Park in northern Australia. Two sites were sampled inside the park and one site was sampled outside the park, covering two management zones: open and partially protected. During the austral summer, 85 individuals of 12 species of elasmobranch were observed over 12 days. No significant differences were observed among sites in either size or abundance for common species. Videos were dominated by Carcharhinus melanopterus (relative abundance±s.d., 0.29±0.90h–1), Nebrius ferrugineus (0.03±0.24h–1) and Urogymnus granulatus (0.08±0.28h–1), which comprised >81% of all individuals. Environmental variables had no measurable effect on the abundance of elasmobranchs. The abundance and diversity of elasmobranchs in Cobourg Marine Park is high compared with other similar turbid, inshore areas of northern Australia. The large number of juveniles observed in our surveys also suggests the possibility of a nursery area.
Structural basis of the UDP-diacylglucosamine pyrophosphohydrolase LpxH inhibition by sulfonyl piperazine antibiotics
Authors: Cho Jae , Lee Minhee , Cochrane C. Skyler , Webster Caroline G. , Fenton Benjamin A. , Zhao Jinshi , Hong Jiyong , Zhou Pei
Published: February 2020

The UDP-2,3-diacylglucosamine pyrophosphate hydrolase LpxH is an essential lipid A biosynthetic enzyme that is conserved in the majority of gram-negative bacteria. It has emerged as an attractive novel antibiotic target due to the recent discovery of an LpxH-targeting sulfonyl piperazine compound (referred to as AZ1) by AstraZeneca. However, the molecular details of AZ1 inhibition have remained unresolved, stymieing further development of this class of antibiotics. Here we report the crystal structure of
Klebsiella pneumoniae
LpxH in complex with AZ1. We show that AZ1 fits snugly into the
L
-shaped acyl chain-binding chamber of LpxH with its indoline ring situating adjacent to the active site, its sulfonyl group adopting a sharp kink, and its
N
-CF
3
–phenyl substituted piperazine group reaching out to the far side of the LpxH acyl chain-binding chamber. Intriguingly, despite the observation of a single AZ1 conformation in the crystal structure, our solution NMR investigation has revealed the presence of a second ligand conformation invisible in the crystalline state. Together, these distinct ligand conformations delineate a cryptic inhibitor envelope that expands the observed footprint of AZ1 in the LpxH-bound crystal structure and enables the design of AZ1 analogs with enhanced potency in enzymatic assays. These designed compounds display striking improvement in antibiotic activity over AZ1 against wild-type
K. pneumoniae
, and coadministration with outer membrane permeability enhancers profoundly sensitizes
Escherichia coli
to designed LpxH inhibitors. Remarkably, none of the sulfonyl piperazine compounds occupies the active site of LpxH, foretelling a straightforward path for rapid optimization of this class of antibiotics.