bluuebunny/crossref_metadata_2025 huggingface dataset:
Microfluidic solution-processed organic and perovskite nanowires fabricated for field-effect transistors and photodetectors
Authors: Chen Ping-An , Guo Jing , Nouri Mehdi , Tao Quanyang , Li Zhiwei , Li Qianyuan , Du Lulu , Chen Huajie , Dong Zaizai , Chang Lingqian , Liu Yuan , Liao Lei , Hu Yuanyuan
Published: January 2020

A microfluidic template method of fabricating nanowires with solution-processable semiconductors is demonstrated, which can be utilized for constructing nanowire-based devices.
Laser floating zone growth of Yb, or Nd, doped (Lu0.3Gd0.7)2SiO5 oxyorthosilicate single-crystal rods with efficient laser performance
Authors: Rey-García F. , Costa F. M. , Zaldo C.
Published: January 2020

Laser quality single crystals of Yb- and Nd-doped oxyorthosilicates, (Lu0.3Gd0.7)2SiO5, have been grown by the laser floating zone technique.
Proposing a new method for improving RPL to support mobility in the Internet of things
Authors: Hoghooghi Samaneh , Javidan Reza
Published: January 2020

The internet engineering task force working group has proposed IPv6 Routing Protocol for Low‐power and Lossy (RPL) networks for the energy‐constrained networks on the Internet of things. This protocol has limitations and does not pay particular attention to mobile nodes. We introduce a new method to improve the RPL protocol with the aim to provide continuous connectivity for mobile nodes. Using additional fields to RPl control packets, a parent is responsible for mobility detection and informs a mobile node for maintaining the energy of it and reduces network overheads. A mobile node chooses a new parent based on metrics namely expected transmission count, received signal strength indicator and residual energy, before disconnection from previous parent. Memory has also been defined that maintains a list of previous parents and when selecting a new parent, a mobile node gets help from this list to select stable parents. They used the Cooja simulator to evaluate the performance of the proposed protocol and the results compared with the RPL and mRPL from the aspect of packet delivery ratio, network overhead, end‐to‐end delay, energy consumption, and end‐to‐end throughput under different scenarios. The simulation results showed the effectiveness of the proposed method.
Reduction of patient radiation dose during percutaneous CT vertebroplasty: Impact of a new computer-assisted navigation (CAN) system
Authors: Teriitehau C. , Rabeh H. , Pessis E. , Sénéchal Q. , Besse F. , Bravetti M.
Published: January 2020

To assess the impact of a computer assisted navigation system (CAN) (CT-Navigation™ IMACTIS, France) on patient radiation doses during percutaneous CT vertebroplasty a retrospective comparative trial was performed and included 37 patients requiring percutaneous vertebroplasty. This study was approved by CCN (Centre Cardiologique du Nord, Saint-Denis, France) ethical committee; all patients provided informed consent. All procedures were conducted in the interventional radiology department at CCN, by an experienced single radiologist using the same model and CT scan with identical parameters. The interventional dose length product (IDLP), representing the absorbed dose by the length of explored organs during the needle insertion phase, was compared in 15 consecutive patients who underwent a conventional procedure (CT control group), and in 22 patients who underwent CAN CT vertebroplasty (CAN group). The IDLP difference between the two groups was evaluated using Mann–Whitney U test. The median IDLP dose for the CAN group was 305.6 mGy.cm [182.3; 565.4], representing a reduction by a 3.2 factor compared with that of the conventional CT group (median 975.2 mGy.cm [568.3; 1077.1]; p < 0.001). The median procedure duration for the CAN group was 50 min [35; 60] vs. 100 min [82; 100] in the CT group (p < 0.001), representing a 50% reduction. In experienced hands, use of a CT-Navigation™ system (IMACTIS®) significantly reduced both patient radiation dose and procedure duration when compared to conventional CT guided percutaneous vertebroplasty.
Surgical Treatment of Talar Neck and Body Fractures: Mid-Term Results of 24 Cases
Authors: von Winning Dominik , Adolf Daniela , Schirrmeister Wiebke , Piatek Stefan
Published: January 2020

Background Talar neck and body fractures are rare. Major posttraumatic complications with a potential reduction in the quality of life are arthrosis and necrosis due to the specific vascular supply. The aim of the study was to evaluate mid-term results of surgery for talar fractures of neck and body. Parameters that potentially affected/influenced treatment outcomes were analysed exploratively.

Methods 24 patients with 24 talar neck and body fractures (Marti type II n = 9, type III n = 12, type IV n = 3) were retrospectively examined for radiological and clinical functional outcomes. The independent parameters evaluated included age (< 40, ≥ 40 years), sex (male, female), general overall extent of injury (polytrauma/multiple injuries/multiple fractures of the extremities, additional injuries to the same foot, isolated talus fracture), soft tissue damage (open, closed), surgical latency (< 6, ≥ 6 h), fracture classification/displacement (undisplaced [= Marti II], displaced [= Marti III, IV]) and fracture type (talar body, neck fracture). The potential influencing parameters were analysed by univariate analyses.

Results With an average follow-up of 8.7 years (1,25 – 16 years) the AOFAS score was 71.4 ± 22.9 points, the Foot Function Index score 35.9 ± 28.3 points; the physical and mental component summary scores of the Short Form 36, version 2, was 43.8 ± 10.9 and 47.4 ± 13.6 points (mean ± standard deviation), respectively. Thus, the patient reported physical health of the patients was slightly reduced compared to the German population, while the mental health remained largely unaffected. Two patients developed partial avascular necrosis (8%), 10 patients developed osteoarthritis (42%). Of the independent parameters, only the general overall extent of injury showed a significant influence on osteoarthritis (p = 0.002). In the evaluation of undisplaced (n = 9) and displaced (n = 15) fractures, surgical treatment after more than 6 hours did not result in a worse outcome.

Conclusion The clinical outcome of internal fixation of talar neck and body fractures can be classified as good. In the study group, there was no correlation between the occurrence of arthrosis and the Marti fracture classification.
Gedeihstörung, Hyponatriämie, Hyperkaliämie – Differenzialdiagnostische Überlegungen einer seltenen genetischen Erkrankung
Authors: Tropschuh Andrea , de Potzolli Brigitte , Seeliger Stephan
Published: January 2020

Der Pseudohypoaldosteronismus Typ I ist eine seltene genetische Erkrankung einer Mineralokortikoidresistenz, die sich typischerweise im Neugeborenenalter manifestiert. Die Patienten fallen durch eine Gedeihstörung, Dehydratation, Polyurie, Erbrechen, Hyperkaliämie, Hyponatriämie sowie gegebenenfalls einer metabolischen Azidose bei erhöhten Aldosteron – und Plasmareninwerten auf. Das Krankheitsbild wird in eine systemische und renale Form unterteilt. Bei der renalen Form besteht nach alleiniger Kochsalzsubstitution ab dem Kleinkindesalter eine Symptomfreiheit. Bei der systemischen Form können neben den Nieren auch Kolon, Lungen, Speichel- und Schweißdrüsen betroffen sein. Dabei zeigt sich eine Symptompersistenz bis in das Erwachsenenalter.
Work and Training Conditions of German Residents in Radiology – Results from a Nationwide Survey Conducted by the Young Radiology Forum in the German Roentgen Society
Authors: Oechtering Thekla H. , Panagiotopoulos Nikolaos , Völker Martin , Lohwasser Stefan , Ellmann Stephan , Molwitz Isabel , Storz Corinna , Winther Hinrich , Eisenblaetter Michel , Antoch Gerald , Schönberg Stefan O. , Barkhausen Jörg , Anton Frank , Neumann Stefan , Layer Günter , Doerfler Arnd , Koerber Friederike , Wessling Johannes , Wucherer Michael , Raspe Matthias
Published: January 2020

Purpose Good training is the basis for high job satisfaction and high-quality patient care in radiology. The aim of this survey was to record the current state of working conditions for residents in radiology training in Germany and to focus on the aspects of training and psychosocial workload. The description of the actual state should help to identify possible problem areas and to develop improvement approaches.

Materials and Methods At the beginning of 2018, we sent an electronic questionnaire to the German Roentgen Society (DRG), the German Association of Chairmen in Academic Radiology (KLR), the Chief Physician Forum of the DRG (CAFRAD) and the Forum of Registered Radiologists (FUNRAD) with the request to forward it to radiology residents. With 63 questions, the questionnaire covered seven essential areas of medical working and training conditions. In order to ensure interdisciplinary comparability, most questions were identical to previous surveys among residents of other disciplines.

Results 643 residents started the survey. 501 (78 %) questionnaires were fully processed and included in the final analysis. 65 % of respondents were satisfied with their current job situation. At the same time, shortcomings, especially with regard to the reconciliation of family and work as well as scientific and clinical work, became clear. Only 36 % of participants with children were satisfied with the compatibility of family and work at their workplace. Only 31 % of the researchers were satisfied with their research conditions. In addition, residents experienced a high psychosocial workload.

Conclusion Job satisfaction is high among radiology residents in direct comparison to other disciplines. However, based on this survey, adjustments to working conditions and training in radiology seem necessary to maintain the health of the physicians concerned, to encourage motivation for scientific work and to enhance development opportunities, especially for women, through a better compatibility of work and family life. The present survey identifies strategies and leadership tools that can help to achieve this.

Key Points: 

Residents in radiology training ...

Citation Format
Home Self-Administration of Biologics – A German Survey among Omalizumab-Treated Patients with Severe Asthma and their Treating Physicians
Authors: Timmermann H. , Mailänder C.
Published: January 2020

In the EU, five biologics have been approved as add-on therapy for patients with severe asthma. Until recently, none of the biologics was approved for home use and had to be administered under medical supervision, a time-consuming schedule for both patients and physicians, accompanied by greater expenditure. However, over the last year, four out of the five biologics have been granted approval for patient self-administration at home. The objective of this multiple-choice survey was to understand how patients with severe asthma treated with omalizumab and their treating physicians view the potential home use of biologics exemplified by omalizumab. The questionnaires were answered by 120 physicians and 432 patients (response rate: 51.7 % and 20.6 %, respectively). Overall, 44.7 % of patients were in favour of self-administration at home while 30.6 % opposed this method of administration and 23.8 % of patients were neutral. Especially teenagers and young adults had a positive attitude towards self-administration. 76.7 % of the questioned physicians were in favour of home use for certain patients. Time saving was the main advantage for self-administration mentioned by patients (53.2 %) as well as by physicians (72.5 %). The main concern for patients was ‘making a mistake while injecting’ (43.8 %) while ‘forgetting to inject omalizumab’ (73.3 %) was the main concern for physicians. 44.4 % of patients expressed a wish for individual training and 70.8 % of physicians agreed with this statement. The latter group also considered a starter kit including several information materials (54.2 %) as well as an electronic reminder system (50.8 %) as useful. In conclusion, self-administration of biologics has the potential to be timesaving for both patients and physicians.
Synthesis of N-Heterocycles via Transition-Metal-Catalyzed Tandem Addition/Cyclization of a Nitrile
Authors: Hsieh Jen-Chieh , Su Haw-Lih
Published: January 2020

The diverse methodologies to synthesize N-heterocycles through transition-metal-catalyzed cascade addition/cyclization of a nitrile are discussed in this review. Aspects relating to three types of transition-metal-catalyzed addition of a nitrile with subsequent cyclization include (1) a transition-metal acting as a Lewis acid to accelerate the nucleophilic addition of a nitrile, (2) the late-transition-metal-catalyzed 1,2-insertion of a nitrile, and (3) an in situ generated radical by transition-metal catalysis to implement a radical addition/cyclization tandem reaction. Applications for the synthesis of natural alkaloids, their derivatives, and some bioactive compounds are also summarized herein.

1 Introduction

2 Nucleophilic Addition of a Nitrile Accelerated by a Lewis Acid

2.1 Late-Transition-Metal Catalysis

2.2 Early-Transition-Metal Catalysis

2.3 Lanthanide-Metal Catalysis

2.4 Cyclization from N-Arylnitriliums

3 Transition-Metal-Catalyzed Insertion of a Nitrile

4 Transition-Metal-Catalyzed Radical Addition of a Nitrile

5 Conclusions
TMSOTf-Promoted Sulfinylation of Electron-Rich Aromatics with Sodium Arylsulfinates
Authors: Li Hui-Jing , Wu Yan-Chao , Ji Yuan-Zhao , Yang Hao-Ran , Zhang Zheng-Yan , Xie Li-Jun
Published: January 2020

A new transition-metal-free route for the direct sulfinylation of electron-rich aromatics with sodium arylsulfinates in the presence of TMSOTf is reported. Various electron-rich aromatics, including pyrroles, thiophenes, indoles, and electron-rich arenes, with sodium arylsulfinates are converted into the corresponding sulfoxides in moderate to excellent yields. This protocol possesses many advantages such as readily available and stable starting materials, broad substrate scopes, and transition-metal-free reaction conditions.
An Improved, Practical, and Scalable Five-Step Synthesis of Psilocybin
Authors: Kargbo Robert B. , Sherwood Alexander M. , Meisenheimer Poncho , Tarpley Gary
Published: January 2020

Described herein is an improved synthesis of 3-[2-(dimethylamino)ethyl]-1H-indol-4-yl dihydrogen phosphate (psilocybin). The protocol outlines: synthesis of multigram quantities of psilocybin, identification of critical in-process parameters, and isolation of psilocybin without the use of chromatography, TLC, or aqueous workup. The synthesis furnishes psilocybin in five steps in 23% overall yield from an inexpensive acetoxyindole starting material. With specific focus on process control and impurity fate and removal, the improved procedure is amenable to providing high-quality psilocybin.
Double Aortic Arch Mimics the Clinical Characteristics of Severe Reactive Airway Disease in a Pediatric Patient
Authors: Yesilbas Osman , Kus Hazar Dogus , Şik Güntülü , Citak Agop , Temur Bahar , Yozgat Can Yilmaz , Temur Hafize Otcu , Cakir Erkan , Yozgat Yilmaz
Published: January 2020

Reactive airway disease is a prevalent condition that can be detected in the early infancy period. The condition might also deteriorate into asthma in some cases. If infants do not respond to the treatment of persistent wheeze and coughing, other rare causes should be investigated. The complete form of vascular ring is an extremely uncommon congenital cardiovascular abnormality. Double aortic arch constitutes the most significant portion of the complete vascular ring anomalies. Clinical manifestations of the anomaly are mainly respiratory due to the tracheal compression and mimicking the conditions of asthma. There have not been many reports about the clinical presentations of double aortic arch being remarkably similar to the same clinical manifestations of asthma in the literature. As far as we can be sure, there have not been any reported cases about severe reactive airway disease that caused a patient to have a life-threatening condition in the pediatric intensive care unit. Herein, we present a 5-month-old girl who had double aortic arch. Her anatomical aberration was diagnosed by three-dimensional computed tomography angiography of thorax, and the anomaly mimicked the clinical characteristics of life-threatening severe reactive airway disease.
Carpal Extension Angles in Agility Dogs Exiting the A-Frame and Hurdle Jumps
Authors: Castilla Andrea , Knotek Brooke , Vitt Molly , Gordon-Evans Wanda
Published: January 2020

Objectives The aim of this study was to determine the mean carpal extension angles in dogs participating in the A-frame and hurdle jumps, and to determine if the use of a carpal brace changed the carpal extension angle.

Study Design Data from 13 healthy agility dogs were included. Approximately 1 cm square adhesive tape markers placed on both forelimbs served as anatomic landmarks for carpal angle measurement. Each dog was filmed landing after jumping over a bar and exiting the A-frame. Five valid trials on each obstacle were collected. The carpal braces were then applied and the dogs were allowed to navigate obstacles for 10 minutes. Once acclimated to the brace, an additional five valid trials were collected. Carpal extension was measured from the videos collected using a video analysis software.

Results Without the carpal brace, the mean carpal extension angles ± standard deviations in dogs participating in the A-frame and hurdle jumps were 124.7 ± 11.9 degrees and 123.3 ± 6.3 degrees, respectively. With the carpal brace, the mean carpal extension angles ± standard deviations were 129.1 ± 11.4 degrees and 125.3 ± 7.3 for the A-frame and hurdle jumps, respectively. There was no clinically significant reduction as defined (>10 degrees) in carpal extension measurements with and without the brace.

Clinical Significance The brace used in this study did not show a clinically significant reduction in carpal extension. However, multiple avenues for future research have been identified using these data.
Moyamoya Syndrome in a Child with β-Thalassemia Major
Authors: Roy Soumya
Published: January 2020

A 9-year-old girl patient presented with left-sided weakness and joint contractures developing over a period of 18 months. She was known to be suffering from β-thalassemia major and was on regular blood transfusions. Eighteen months ago, she had suffered from an episode of ischemic cerebrovascular accident affecting the right side of her brain. Magnetic resonance angiogram revealed vaso-occlusive disease affecting mainly the anterior cerebral circulation, resembling Moyamoya disease. She was advised to carry out regular physiotherapy but her parents discontinued it, which resulted in the gradual development of joint contractures and muscle wasting.
Different Patellar Indices and Their Role in Decision-Making: An MRI-Based Study
Authors: Raju Sivashanmugam , Chinnakkannu Karthikeyan , Balakumar Balasubramanian , Sundareyan Ramanivas , Kaliappan Saravanakumar P. , Puttaswamy Mohan K.
Published: January 2020

Magnetic resonance imaging (MRI) of knee has become the integral part of knee evaluation, hence any MRI based study adds more value if it helps in the decision-making process, especially for surgery in treating patellofemoral pain. We tried to determine normal patellar indices using knee MR images and the correlation between them and also compared the results with different ethnic population. We analyzed the prospectively collected MR images of 117 knees/patients, and Insall–Salvati (IS) index, modified IS index, patellotrochlear (PT) index, and patellophyseal (PP) index were calculated. Two standard deviations from the mean were used to define the normal and abnormal patellar position. Cohen's kappa values were used to assess the agreement between the indices and the correlation between them was analyzed using Pearson's correlation. The mean values for IS index, modified IS index, PT index, and PP index were 1.00, 1.53, 0.40, and 0.58, respectively. There was very good agreement between PT index and PP index. There was weak correlation between all the indices except the one between PT and PP indices which had a strong negative correlation. Based on commonly used methodology, there were 4% of asymptomatic patients who were outside the standardized cut-off values and different indices classified different knees as abnormal. This indicates patellar position should be one among the many other factors, not as a sole factor when making a surgical decision in patellofemoral pain. We also noted that the indices compared fairly with other populations. Further research is needed to determine the clinical applicability of these indices.
Transforming French Electronic Health Records into the Observational Medical Outcome Partnership's Common Data Model: A Feasibility Study
Authors: Lamer Antoine , Depas Nicolas , Doutreligne Matthieu , Parrot Adrien , Verloop David , Defebvre Marguerite-Marie , Ficheur Grégoire , Chazard Emmanuel , Beuscart Jean-Baptiste
Published: January 2020

Background Common data models (CDMs) enable data to be standardized, and facilitate data exchange, sharing, and storage, particularly when the data have been collected via distinct, heterogeneous systems. Moreover, CDMs provide tools for data quality assessment, integration into models, visualization, and analysis. The observational medical outcome partnership (OMOP) provides a CDM for organizing and standardizing databases. Common data models not only facilitate data integration but also (and especially for the OMOP model) extends the range of available statistical analyses.

Objective This study aimed to evaluate the feasibility of implementing French national electronic health records in the OMOP CDM.

Methods The OMOP's specifications were used to audit the source data, specify the transformation into the OMOP CDM, implement an extract–transform–load process to feed data from the French health care system into the OMOP CDM, and evaluate the final database.

Results Seventeen vocabularies corresponding to the French context were added to the OMOP CDM's concepts. Three French terminologies were automatically mapped to standardized vocabularies. We loaded nine tables from the OMOP CDM's “standardized clinical data” section, and three tables from the “standardized health system data” section. Outpatient and inpatient data from 38,730 individuals were integrated. The median (interquartile range) number of outpatient and inpatient stays per patient was 160 (19–364).

Conclusion Our results demonstrated that data from the French national health care system can be integrated into the OMOP CDM. One of the main challenges was the use of international OMOP concepts to annotate data recorded in a French context. The use of local terminologies was an obstacle to conceptual mapping; with the exception of an adaptation of the International Classification of Diseases 10th Revision, the French health care system does not use international terminologies. It would be interesting to extend our present findings to the 65 million people registered in the French health care system.
Igniting Harmonized Digital Clinical Quality Measurement through Terminology, CQL, and FHIR
Authors: McClure Robert C. , Macumber Caroline L. , Skapik Julia L. , Smith Anne Marie
Published: January 2020

Background Electronic clinical quality measures (eCQMs) seek to quantify the adherence of health care to evidence-based standards. This requires a high level of consistency to reduce the effort of data collection and ensure comparisons are valid. Yet, there is considerable variability in local data capture, in the use of data standards and in implemented documentation processes, so organizations struggle to implement quality measures and extract data reliably for comparison across patients, providers, and systems.

Objective In this paper, we discuss opportunities for harmonization within and across eCQMs; specifically, at the level of the measure concept, the logical clauses or phrases, the data elements, and the codes and value sets.

Methods The authors, experts in measure development, quality assurance, standards and implementation, reviewed measure structure and content to describe the state of the art for measure analysis and harmonization. Our review resulted in the identification of four measure component levels for harmonization. We provide examples for harmonization of each of the four measure components based on experience with current quality measurement programs including the Centers for Medicare and Medicaid Services eCQM programs.

Results In general, there are significant issues with lack of harmonization across measure concepts, logical phrases, and data elements. This magnifies implementation problems, confuses users, and requires more elaborate data mapping and maintenance.

Conclusion Comparisons using semantically equivalent data are needed to accurately measure performance and reduce workflow interruptions with the aim of reducing evidence-based care gaps. It comes as no surprise that electronic health record designed for purposes other than quality improvement and used within a fragmented care delivery system would benefit greatly from common data representation, measure harmony, and consistency. We suggest that by enabling measure authors and implementers to deliver consistent electronic quality measure content in four key areas; the industry can improve quality measurement.
High-stability, high-voltage power supplies for use with multi-reflection time-of-flight mass spectrographs
Authors: Schury P. , Wada M. , Wollnik H. , Moon J.-Y. , Hashimoto T. , Rosenbusch M.
Published: January 2020

Achieving the highest possible mass resolving power in a multireflection time-of-flight mass spectrometer requires very high-stability power supplies. To this end, we have developed a programmable high-voltage power supply that can achieve long-term stability in the order of parts-per-million. Herein, we present the design of a stable high-voltage system and bench-top stability measurements up to 1 kV; a stabilization technique can, in principle, be applied up to 15 kV or more. We demonstrate that in the ≤1 Hz band, the output stability is at the level of 1 part per million (ppm) for 1 h, with only slightly more output variation across 3 days. We further demonstrate that the output is largely free of noise in the 1 Hz–200 Hz band. We also demonstrate settling to the ppm level within 1 min following a 100 V step transition. Finally, we demonstrate that when these power supplies are used to bias the electrodes of a multireflection time-of-flight mass spectrograph, the measured time-of-flight is stable at the ppm-level for at least 1 h.
Compression of laser pulses by near-forward Raman amplification in plasma
Authors: Wu Z. , Chen Q. , Morozov A. , Suckewer S.
Published: January 2020

We propose a new scheme for compression of ultrashort laser pulses enabled by Near-Forward Raman Amplification (NFRA) in plasma. In contrast to traditional forward Raman amplification in plasma, the seed pulse in NFRA propagates faster than the pump through manipulation of the spatiotemporal properties of the pump beam. A “π-pulse” solution similar to that of stimulated Raman backscattering amplification is obtained, indicating that NFRA can be used for compression of ultrashort laser pulses. NFRA is numerically demonstrated with a 2D simulation using a front-tilt near-forward pump pulse.
Control of spin and valley Hall effects in monolayer transition metal dichalcogenides by magnetic proximity effect
Authors: Da Haixia , Song Qi , Dong Peng , Ye Huapeng , Yan Xiaohong
Published: January 2020

Monolayer transition metal dichalcogenides have strong spin–orbit coupling and broken space inversion symmetry, which enable them to be the key building blocks in realizing spin and valley-related effects. Here, we report the spin and valley Hall conductivities of monolayer transition metal dichalcogenides in the presence of the magnetic proximity effect, which is introduced by a ferromagnetic substrate. It is found that the profile and magnitude of the spin and valley Hall conductivities in monolayer transition metal dichalcogenides are different with and without magnetic exchange interactions. This difference can be attributed to the asymmetrical band structure of monolayer transition metal dichalcogenides and chemical potential-dependent interband transitions. The former comes from the fact that the magnetic proximity effect can effectively break the time reversal symmetry and thus lead to the asymmetry of the band structures between K+ and K− valleys, which causes the final changes in the spin and valley Hall conductivities. Our findings demonstrate that the magnetic proximity effect can affect the spin as well as valley Hall behaviors in monolayer transition metal dichalcogenides, and this strategy is applicable for other two-dimensional layered materials, which is promising for spintronic and valleytronic devices.
Turbulent flow interaction with a circular cylinder
Authors: Maryami Reza , Showkat Ali Syamir Alihan , Azarpeyvand Mahdi , Afshari Abbas
Published: January 2020

This paper presents a comprehensive experimental study on the unsteady pressure exerted on the surface of a round cylinder in smooth and turbulent flows. A highly instrumented cylinder with several static pressure taps and dynamic pressure transducers at different spanwise and peripheral locations was used, enabling extensive dynamic surface pressure, coherence, and turbulence length-scale analysis. The effects of the free-stream turbulence and turbulent length scale are investigated by placing the turbulent-generating grids within the wind tunnel duct. For both the laminar and turbulent incident flows, the surface pressure results show the emergence of the fundamental, first and second harmonics at most peripheral angles, while at the cylinder base, the surface pressure spectra are dominated by the first harmonic. It has also been observed that an increase in the level of the turbulence intensity results in an increase in the energy level of unsteady pressure acting on the cylinder. An increase in the length scale of the incoming flow structures is shown to result in an increase in the energy level of the tonal frequencies and the broadband content of the surface pressure spectra. The spanwise coherence results have also shown that an increase in the length scale of the flow structures increases the spanwise correlation length of the flow structures at the vortex shedding frequency at the stagnation point, while at the cylinder base, the spanwise correlation length decreases at the vortex shedding frequency.
Modulational instability of dust-ion acoustic waves in the presence of generalized (r, q) distributed electrons
Authors: El-Bedwehy N. A. , El-Taibany W. F.
Published: January 2020

We have investigated the modulational instability (MI) of dust-ion acoustic waves in a dusty plasma model containing warm ions fluid, generalized  (r, q) distributed electrons, and immobile dust grains. Using the Krylov-Bogoliubov-Mitropolsky method, the amplitude modulation of a monochromatic plane wave is analyzed through derivation of a nonlinear Schrödinger equation. The MI condition is calculated. Moreover, the effects of the plasma parameters such as the ion-to-electron temperature ratio, the wavenumber, and the unperturbed dust-to-electron number density ratio as well as the electron distribution dual parameters (r, q) are discussed. Our investigations have shown that the unstable region is bounded by two stable regions, i.e., two critical wavenumbers [kcl(lower) and kch(higher)] are found. The applications of the present theoretical study are briefly discussed in space physics whether positive or negative dust grains are enclosed.
Role of temperature-dependent electron trapping dynamics in the optically driven nanodomain transformation in a PbTiO3/SrTiO3 superlattice
Authors: Park Joonkyu , Ahn Youngjun , Tilka Jack A. , Lee Hyeon Jun , Pateras Anastasios , Yusuf Mohammed H. , Dawber Matthew , Wen Haidan , Evans Paul G.
Published: January 2020

The spontaneously formed striped polarization nanodomain configuration of a PbTiO3/SrTiO3 superlattice transforms to a uniform polarization state under the above-bandgap illumination with a time dependence varying with the intensity of optical illumination and a well-defined threshold intensity. The recovery after the end of illumination occurs over a temperature-dependent period of tens of seconds at room temperature and shorter times at elevated temperatures. A model in which the screening of the depolarization field depends on the population of trapped electrons correctly predicts the observed temperature and optical intensity dependence.
Best practices for high data-rate macromolecular crystallography (HDRMX)
Authors: Bernstein Herbert J. , Andrews Lawrence C. , Diaz Jorge A. , Jakoncic Jean , Nguyen Thu , Sauter Nicholas K. , Soares Alexei S. , Wei Justin Y. , Wlodek Maciej R. , Xerri Mario A.
Published: January 2020

In macromolecular crystallography, higher flux, smaller beams, and faster detectors open the door to experiments with very large numbers of very small samples that can reveal polymorphs and dynamics but require re-engineering of approaches to the clustering of images both at synchrotrons and XFELs (X-ray free electron lasers). The need for the management of orders of magnitude more images and limitations of file systems favor a transition from simple one-file-per-image systems such as CBF to image container systems such as HDF5. This further increases the load on computers and networks and requires a re-examination of the presentation of metadata. In this paper, we discuss three important components of this problem—improved approaches to the clustering of images to better support experiments on polymorphs and dynamics, recent and upcoming changes in metadata for Eiger images, and software to rapidly validate images in the revised Eiger format.
Water exit dynamics of jumping archer fish: Integrating two-phase flow large-eddy simulation with experimental measurements
Authors: Khosronejad Ali , Mendelson Leah , Techet Alexandra H. , Kang Seokkoo , Angelidis Dionysios , Sotiropoulos Fotis
Published: January 2020

Archer fish jumping for prey capture are capable of achieving accelerations that can reach 12 times gravitational from a stationary start at the free surface. This behavior is associated with nontrivial production of hydrodynamic thrust. In this work, we numerically investigate the hydrodynamic and aerodynamic performance of a jumping smallscale archer fish (Toxotes microlepis) to elucidate the propulsive mechanisms that contribute to the rapid acceleration and the considerable jump accuracy. We conduct high-fidelity, two-phase flow, large-eddy simulation (LES) of an anatomically realistic archer fish using detailed jump kinematics in water, through the water/air interface, and in air. The complex fish body kinematics are reconstructed using high-speed imaging. The LES results during the water phase of the jump are compared with particle image velocimetry measurements of a live jumping archer fish, and excellent agreement is found. The numerical simulations further enable detailed analysis of the flow dynamics and elucidate for the first time the dynamics of the coherent vortical structures in both the water and air phases. In particular, the pectoral fins are shown to contribute to the initial spike in acceleration before water exit and to enhance the overall jumping performance of the fish.
Effects of short-range order and interfacial interactions on the electronic structure of two-dimensional antimony-arsenic alloys
Authors: An Qi , Fortin-Deschênes Matthieu , Yu Guanghua , Moutanabbir Oussama , Guo Hong
Published: January 2020

The recent demonstration of the growth of two-dimensional (2D) antimony-arsenic alloys provides an additional degree of freedom to tailor the basic properties of the emerging group-V 2D materials. With this perspective, herein, we propose and conduct a comprehensive first-principles investigation on this 2D group-V antimony arsenide (2D AsxSby), in both free-standing form as well as on the common substrates of Ge(111), Si(111), bilayer graphene, and bilayer hexagonal boron nitride (h-BN). Structural and electronic properties of the 2D AsxSby are evaluated for different compositions, different types of atomic arrangements for each composition, and different lattice matched interfacial configurations of the composite heterostructures for the four substrates. These systematic studies provide property benchmarks for this new class of group-V 2D materials. This analysis reveals microscopic origins of the interfacial interactions, orbital hybridization, charge transfer, and the resulting electronic structures of the 2D alloy. We predict that a change in the frontier states leads to an indirect-direct bandgap transition according to atomic arrangements in the monolayer AsxSby. On substrates, the relatively strong interfacial interaction between Ge or Si with AsxSby suppresses the semiconducting properties exhibited in free layers, while the weak van der Waals interaction between graphene or h-BN with AsxSby preserves the bands of the alloy. We conclude that 2D group-V alloys AsxSby give a large material phase-space with very interesting electronic properties.
Application of spectral proper orthogonal decomposition to velocity and passive scalar fields in a swirling coaxial jet
Authors: Kadu Pravin Ananta , Sakai Yasuhiko , Ito Yasumasa , Iwano Koji , Sugino Masatoshi , Katagiri Takahiro , Hayase Toshiyuki , Nagata Koji
Published: January 2020

Direct numerical simulation is used to study unconfined coaxial jets under the influence of strong swirl imparted to the outer jet. Spectral proper orthogonal decomposition is employed to elucidate the physically important structures or modes in the flow. The analysis is extended to the transport of passive scalars injected through each jet. A partially penetrated vortex breakdown bubble is formed as a result of the strong swirl. In the region upstream of the central stagnation point, the first two (most energetic) spatial modes of the velocity field at the cross-stream section reveal three pairs of counter-rotating vortical structures, while the succeeding two modes reveal four pairs of such structures. The centers of these vortical structures are found to lie in the inner mixing layer present between the two jets. The corresponding spatial modes of the scalars also exhibit organized lobelike structures in this region. These organized structures are subsequently disrupted in the downstream region. The significance of these pairs of counter-rotating vortical structures is demonstrated by reconstruction of various turbulence statistics, namely, the root mean square (rms) velocities, the rms scalar fluctuations, the covariance between the two scalars, and the radial turbulent fluxes of the scalars. The results show that the first four modes make a greater contribution to these statistics except for the covariance between two scalars, particularly in the inner mixing layer.
Gate-voltage-driven quantum oscillations in the microwave third-harmonic response of electron-doped graphene nanoribbons
Authors: Margulis Vl. A. , Muryumin E. E.
Published: January 2020

Microwave third-harmonic response of narrow graphene nanoribbons (GNRs) is studied by employing Boltzmann equation techniques. It is assumed that the GNRs are electron-doped by electrostatic gating. We predict gate-voltage-driven periodic quantum oscillations of the microwave third-harmonic output power from such GNRs, resulting from the confinement-induced quantization of the Dirac energy dispersion cones into a set of energy subbands at the bottom of which the electronic density of states exhibits the Van Hove square-root singularities. The oscillations are shown to have a large enough amplitude (∼ several tens of decibel-milliwatts) and should be observable in narrow GNRs of width ∼10 nm even at room temperature.
Bayesian counting of photobleaching steps with physical priors
Authors: Garry Jon , Li Yuchong , Shew Brandon , Gradinaru Claudiu C. , Rutenberg Andrew D.
Published: January 2020

Counting fluorescence photobleaching steps is commonly used to infer the number n0 of monomeric units of individual oligomeric protein complexes or misfolded protein aggregates. We present a principled Bayesian approach for counting that incorporates the statistics of photobleaching. Our physics-based prior leads to a simple and efficient numerical scheme for maximum a posteriori probability (MAP) estimates of the initial fluorophore number n^0. Our focus here is on using a calibration to precisely estimate n^0, though our approach can also be used to calibrate the photophysics. Imaging noise increases with n^0, while bias is often introduced by temporal averaging. We examine the effects of fluorophore number n^0 of the oligomer or aggregate, lifetime photon yield μeff of an individual fluorophore, and exposure time Δt of each image frame in a time-lapse experiment. We find that, in comparison with standard ratiometric approaches or with a “change-point” step-counting algorithm, our MAP approach is both more precise and less biased.
Exciton-polariton dynamics modulated by exciton-photon detuning in a ZnO microwire
Authors: Luo Song , Wang Yafeng , Liao Liming , Zhang Zhe , Shen Xuechu , Chen Zhanghai
Published: January 2020

In a ZnO microcavity, the exciton-polariton effect with ultralarge Rabi splitting (can be as large as several hundreds of millielectron volts) may dominate the optical properties at the energies near the band edge. Due to the light-matter coupling, the renormalized energy states, i.e., the exciton-polariton states are expected to show very different dynamical behavior compared to the free exciton state. In this work, we used a femtosecond laser to pump a high-quality ZnO whispering gallery microcavity at room temperature. In the time-resolved photoluminescence measurements, we observed that both the fast and slow decay rates of the exciton-polaritons are faster than that of the free exciton due to the strong coupling between excitons and photons in a microcavity. The decay time constants are found to depend on the exciton-photon energy detuning (δ=Ephoton−Eexciton).
Spatially resolved light field analysis of the second-harmonic signal of χ(2)-materials in the tight focusing regime
Authors: Spychala K. J. , Mackwitz P. , Widhalm A. , Berth G. , Zrenner A.
Published: January 2020

In this work, the second-harmonic (SH) signal generated by nonlinear optical crystals is studied in the tightly focused regime. The experimental approach is based on an adapted focal imaging technique, which allows the mapping of the SH intensity distribution in the back focal plane via a traversable pinhole in the confocal operation mode. On the theoretical side, a vectorial treatment of the involved optical fields enables the description and interpretation of the occurring interactions by taking into account the applied experimental parameters. The theoretical results are exemplarily validated by comparison to the acquired experimental data gained by the examination of LiNbO3 and KTiOPO4. It is shown how the phase and amplitude of vector components of the incoming electromagnetic field in the focus as well as the local optical properties of the nonlinear optical crystals determine the characteristic nonlinear signals in the back focal plane.
Characterizing three-dimensional features of vortex surfaces in the flow past a finite plate
Authors: Tong Wenwen , Yang Yue , Wang Shizhao
Published: January 2020

We extend the vortex-surface field (VSF), a Lagrangian-based structure identification method, to investigate vortex dynamics in flows past a plate simulated by the immersed boundary method. As an example, the VSF evolution characterizes the three-dimensional features of vortex surfaces in the flow past a finite plate at the Reynolds number of 300, aspect ratio of 2, and angle of attack of 30°. The VSF isosurface displays that near-plate vortex surfaces first roll up from plate edges and then evolve into hairpinlike structures near the leading edge and semiring structures near plate tips and in the wake. We quantitatively distinguish two types of vortical structures by the vanishing streamwise vorticity on VSF isosurfaces and refer them to as the leading edge vortex (LEV) and the tip vortex (TIV). Based on circulations through cross sections of vortex surfaces, we demonstrate that the lift generated from the LEV is suppressed by the finite growth of TIVs. In the wake region, we quantify the geometry of helical vortex lines in TIVs and the contribution of the helical vorticity component to the streamwise vortical impulse.
High-Rayleigh-number thermal convection of compressed gases in inclined rectangular enclosures
Authors: Madanan U. , Goldstein R. J.
Published: January 2020

High-Rayleigh-number convection is experimentally studied using compressed gases for a wide range of Rayleigh numbers (1.85 × 106 ≤ Ra ≤ 1.04 × 1011) and angles of inclination (θ = 0°, 30°, 60°, 90°, 120°, and 150°) with rectangular enclosures of varied aspect ratios (AR = 1, 3, 6, and 10). Experimental results reveal that the Nusselt number decreases monotonically with increasing angle of inclination. Furthermore, for any angle of inclination and a given Rayleigh number, the Nusselt number is observed to follow a decreasing trend with an increase in aspect ratio, which gradually amplifies as the angle of inclination is increased. Z-type shadowgraph flow visualization experiments, employed to characterize buoyant flow behavior at various angles of inclination, confirm the observed heat transfer trends.
Origin of layer decoupling in ordered multilayer graphene grown by high-temperature sublimation on C-face 4H-SiC
Authors: Persson Ingemar , Armakavicius Nerijus , Bouhafs Chamseddine , Stanishev Vallery , Kühne Philipp , Hofmann Tino , Schubert Mathias , Rosen Johanna , Yakimova Rositsa , Persson Per O. Å. , Darakchieva Vanya
Published: January 2020

We study the origin of layer decoupling in ordered multilayer graphene grown by high temperature sublimation on C-face 4H-SiC. The mid-infrared optical Hall effect technique is used to determine the magnetic field dependence of the inter-Landau level transition energies and their optical polarization selection rules, which unambiguously show that the multilayer graphene consists of electronically decoupled layers. Transmission electron microscopy reveals no out-of-plane rotational disorder between layers in the stack, which is in contrast to what is typically observed for C-face graphene grown by low temperature sublimation. It is found that the multilayer graphene maintains AB-stacking order with increased interlayer spacing by 2.4%–8.4% as compared to highly oriented pyrolytic graphite. Electron energy loss spectroscopy mapping reveals Si atoms trapped in between layers, which are proposed to be the cause for the observed increased interlayer spacing leading to layer decoupling. Based on our results, we propose a defect-driven growth evolution mechanism for multilayer graphene on C-face SiC via high temperature sublimation.